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Background: Molecular analyses have shown that tumours diagnosed as supratentorial primitive neuro-ectodermal tumours of the central nervous system (CNS-PNETs) in the past represent a heterogenous group of rare childhood tumours including high-grade gliomas (HGG), ependymomas, atypical teratoid/rhabdoid tumours (AT/RT), CNS neuroblastoma with forkhead box R2 (FOXR2) activation and embryonal tumour with multi-layered rosettes (ETMR). All these tumour types are rare and long-term clinical follow-up data are sparse. We retrospectively re-evaluated all children (0-18 years old) diagnosed with a CNS-PNET in Sweden during 1984-2015 and collected clinical data., Methods: In total, 88 supratentorial CNS-PNETs were identified in the Swedish Childhood Cancer Registry and from these formalin-fixed paraffin-embedded tumour material was available for 71 patients. These tumours were histopathologically re-evaluated and, in addition, analysed using genome-wide DNA methylation profiling and classified by the MNP brain tumour classifier., Results: The most frequent tumour types, after histopathological re-evaluation, were HGG (35%) followed by AT/RT (11%), CNS NB-FOXR2 (10%) and ETMR (8%). DNA methylation profiling could further divide the tumours into specific subtypes and with a high accuracy classify these rare embryonal tumours. The 5 and 10-year overall survival (OS) for the whole CNS-PNET cohort was 45% ± 12% and 42% ± 12%, respectively. However, the different groups of tumour types identified after re-evaluation displayed very variable survival patterns, with a poor outcome for HGG and ETMR patients with 5-year OS 20% ± 16% and 33% ± 35%, respectively. On the contrary, high PFS and OS was observed for patients with CNS NB-FOXR2 (5-year 100% for both). Survival rates remained stable even after 15-years of follow-up., Conclusions: Our findings demonstrate, in a national based setting, the molecular heterogeneity of these tumours and show that DNA methylation profiling of these tumours provides an indispensable tool in distinguishing these rare tumours. Long-term follow-up data confirms previous findings with a favourable outcome for CNS NB-FOXR2 tumours and poor chances of survival for ETMR and HGG., (© 2023. The Author(s).)

We present the case of a 55-year-old woman admitted for a coronary artery bypass operation because of three-vessel coronary artery disease based on angiographic findings and clinical symptoms. Unexpected intraoperative findings with diffuse tissue thickening of the ascending aorta and coronary arteries indicated an alternate pathogenesis rather than coronary artery atherosclerosis. Histopathologic findings and clinical evaluation could confirm IgG4-related disease (IgG4-RD). IgG4-RD is a newly recognized fibroinflammatory condition that can present in a variety of organs and is characterized by common histopathologic features. Low disease awareness among clinicians makes this condition underdiagnosed., (Copyright © 2017 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.)

Brain tumors are the leading cause of cancer-related death in children but high-grade gliomas in children and adolescents have remained a relatively under-investigated disease despite this. A better understanding of the cellular and molecular pathogenesis of the diseases is required in order to improve the outcome for these children. In vitro-cultured primary tumor cells from patients are indispensable tools for this purpose by enabling functional analyses and development of new therapies. However, relevant well-characterized in vitro cultures from pediatric gliomas cultured under serum-free conditions have been lacking. We have therefore established patient-derived in vitro cultures and performed thorough characterization of the cells using large-scale analyses of DNA methylation, copy-number alterations and investigated their stability during prolonged time in culture. We show that the cells were stable during prolonged culture in serum-free stem cell media without apparent alterations in morphology or growth rate. The cells were proliferative, positive for stem cell markers, able to respond to differentiation cues and initiated tumors in zebrafish and mice suggesting that the cells are cancer stem cells or progenitor cells. The cells accurately mirrored the tumor they were derived from in terms of methylation pattern, copy number alterations and DNA mutations. These unique primary in vitro cultures can thus be used as a relevant and robust model system for functional studies on pediatric brain tumors.

Background: Classification of pediatric tumors into biologically defined subtypes is challenging, and multifaceted approaches are needed. For this aim, we developed a diagnostic classifier based on DNA methylation profiles., Results: Methylation data generated by the Illumina Infinium HumanMethylation 450 BeadChip arrays were downloaded from the Gene Expression Omnibus (n = 472). Using the data, we built MethPed, which is a multiclass random forest algorithm, based on DNA methylation profiles from nine subgroups of pediatric brain tumors. DNA from 18 regional samples was used to validate MethPed. MethPed was additionally applied to a set of 28 publically available tumors with the heterogeneous diagnosis PNET. MethPed could successfully separate individual histology tumor types at a very high accuracy (κ = 0.98). Analysis of a regional cohort demonstrated the clinical benefit of MethPed, as confirmation of diagnosis of tumors with clear histology but also identified possible differential diagnoses in tumors with complicated and mixed type morphology., Conclusions: We demonstrate the utility of methylation profiling of pediatric brain tumors and offer MethPed as an easy-to-use toolbox that allows researchers and clinical diagnosticians to test single samples as well as large cohorts for subclass prediction of pediatric brain tumors. This will immediately aid clinical practice and importantly increase our molecular knowledge of these tumors for further therapeutic development.

Purpose: It has been assumed that nucleus pulposus-induced activation of the dorsal root ganglion (DRG) may be related to an activation of sodium channels in the DRG neurons. In this study we assessed the expression of Nav 1.8 and Nav 1.9 following disc puncture., Method: Thirty female Sprague-Dawley rats were used. The L4/L5 disc was punctured by a needle (n=12) and compared to a sham group without disc puncture (n=12) and a naive group (n=6). At day 1 and 7, sections of the left L4 DRG were immunostained with anti-Nav 1.8 and Nav 1.9 antibodies., Result: At day 1 after surgery, both Nav 1.8-IR neurons and Nav 1.9-IR neurons were significantly increased in the disc puncture group compared to the sham and naive groups (p<0.05), but not at day 7., Conclusion: The findings in the present study demonstrate a neuronal mechanism that may be of importance in the pathophysiology of sciatic pain in disc herniation.

The aim of this study was to assess seizure outcome 2 years after epilepsy surgery in a consecutive series of paediatric patients, with special focus on children with learning disabilities and other neuroimpairments in addition to the epilepsy. Outcome 2 years after surgery was assessed in 110 of 125 children operated upon for drug resistant epilepsy in Gothenburg 1987-2006. More than half of the children had learning disabilities, 43% motor impairments and 30% a neuropsychiatric diagnosis. Fifty-six per cent of those with an IQ < 70 became seizure-free or had a >75% reduction in seizure frequency, and two thirds if the operation was a resection. The corresponding figure in those with more than 100 seizures per month was 15 out of 31, and another seven had a 50-75% reduction in seizure frequency. The message is that learning disability, motor impairment and psychiatric morbidity should not be contraindications for paediatric epilepsy surgery. More than half of the children with learning disabilities had a worthwhile seizure outcome, with even better results after resective surgery. Children with drug resistant epilepsy and additional severe neurological impairments should have the benefit of referral to a tertiary centre for evaluation for epilepsy surgery., (Copyright © 2013 European Paediatric Neurology Society. Published by Elsevier Ltd. All rights reserved.)

Background: Intracranial haemangiopericytoma (HPC), a rare malignant tumour, should be distinguished from meningioma and solitary fibrous tumour, which have been considered as separate entities since 1993, according to histopathology and clinical characteristics., Methods: A PUBMED search for "Intracranial Haemangiopericytoma" yielded 176 articles, where 26 were of particular interest for this review article., Case Report: Our patient, a 27-year-old man with HPC of grade III according to WHO, presents with an acute intracerebral haematoma, which is extremely rare., Results: Surgery (total resection) is the primary treatment. Long-term close clinical and radiological follow-up is crucial due to the high rate of recurrence and tendency for development of metastasis., Discussion: The effects of postoperative radiotherapy need further investigation. Besides neurosurgery, radiotherapy should always be considered in both patients with these highly malignant tumours (WHO grade III) and in patients with partial resection or inoperable cases (WHO grade II).

Background: Hereditary diffuse leukoencephalopathy with spheroids (HDLS) was first identified among a Swedish kindred with 17 cases. The average age of onset was 36 years. Autopsy in four cases revealed the presence of axonal spheroids. The causative gene is unknown., Methods: We performed genealogical and longitudinal observations of the original kindred. Forty members were examined, five telephone-interviewed, and one of the original HDLS cases from 1984 was neuropathologically examined. The clinical course was documented. The cerebrospinal fluid (CSF) findings of two recently affected cases were examined, and one of those autopsied., Results: Of those examined, two developed HDLS during our survey and 38 were healthy. Those interviewed by telephone were healthy. One had symptoms suggestive of HDLS in 1984, but autopsy during our survey showed no spheroids. This patient, two relatives healthy at our examination and one without symptoms at telephone interview had HDLS diagnoses in the 1984 report. Thus, four HDLS diagnoses were unconfirmed. The number of identified patients amounts to 15 among 75 individuals in four generations, including two recent cases who demonstrated a subacute multisystem encephalopathy in Case 1 and an insidious course in Case 2. CSF showed signs of neurodegeneration without inflammation, and autopsy verified HDLS in Case 1., Conclusions: Some HDLS cases were misdiagnosed with unspecified psychiatric diagnoses in affected relatives from the original 1984 publication. However, HDLS is an encephalopathy dominated by a frontal lobe syndrome with an inexorably progressive and fatal course, where the different symptomatology in two recent cases confirmed the existence of acute and chronic variants., (© 2011 John Wiley & Sons A/S.)

Background: The aim of the present study was to compare an ultrasonically activated instrument (US), monopolar electrosurgery, and bipolar electrosurgery (ES) with respect to heat production, nerve function, and nerve morphology following in vivo application., Materials and Methods: The biceps femoris muscle of anesthetized rats was cut in a standardized manner longitudinally 1 mm adjacent to the sciatic nerve using US shears, a monopolar ES knife, or a bipolar ES scissors. Activation time and temperature were recorded continuously within 1-4 mm of the activation site ipsilateral and contralateral to the nerve with two thermoelectric microsensors. Temperature rise and time delay of reaching the temperature maximum, as an expression of heat spread within tissue, maximum temperature, and thermal dose (equivalent time of exposure at 43°C) were measured and calculated. A total of 49 functional experiments were conducted. The electromyographic (EMG) potential was recorded distally. Nerve dysfunction was defined as more than 10% loss of the evoked EMG amplitude. Forty-eight nerves were coded and submitted to blind histopathological examination, and morphological damage was graded on a 4-grade scale., Results: The maximum temperature elevation and the thermal dose were significantly higher for the bipolar ES compared with the US instrument (p = 0.024, p = 0.049), and with much less variation of results for the US instrument. The monopolar ES maximum temperature and thermal dose were lower, but a very large variation occurred, probably as a result of more random electrical spread to the ground electrode and muscle motion artifacts. Functional loss was least common in the US group-without being significant-compared to bipolar and monopolar ES. Moderate and severe morphological damage was significantly less common in the US group than in the monopolar ES group (p = 0.041). We found no statistically significant correlation between the highest temperatures and the degree of morphological damage or functional loss., Conclusions: The temperature elevation depends strongly on the distance to the activated instrument. The bipolar ES scissors generates a higher maximum temperature and thermal dose with a greater variation in than the US. Functional loss and severe morphological damage were uncommon in all groups.

We report a case of successful surgical repair of an acute aortic dissection (Stanford Type A) in a severely malnourished 39-year old patient with anorexia nervosa (body mass index [BMI] 11.3 kg/m2) and essential hypertension. The case is of interest since 1) acute aortic dissection in patients with anorexia nervosa has not previously been described; 2) hypertension is extremely rare in patients with eating disorders; and 3) successful aortic repair in a patient with so low BMI has not been reported before. We conclude that extremely low BMI due to anorexia nervosa is not an absolute contraindication for major aortic surgery.

This case concerns a patient with generalized neurosarcoidosis and pharmacoresistant focal epilepsy. Although immunosuppressive therapy resulted in remission of the neurosarcoidosis, seizures continued and were shown to originate from the right temporal lobe (TL). The patient underwent a right anterior temporal lobe resection (TLR) and obtained >90% reduction of seizure frequency.

Galactosialidosis (MIM 256540) is an autosomal recessive lysosomal storage disease caused by a defect of the protective protein/cathepsin A. Increased amounts of urinary sialic acid-rich oligosaccharides are considered to be an essential diagnostic marker of the disease. We here report a patient with atypical clinical features who consistently has excreted normal amounts of sialyloligosaccharides in the urine. The boy started to have attacks of neuropathic pain associated with hyperesthesia around 1(1/2) years of age. From 4 years of age when his vision was first tested, the patient developed progressive visual loss and at the age of 10 years, macular cherry-red spots were found. At this age, he also had a mild learning disability and clinical examination showed mild facial coarsening, increased lumbar lordosis and pyramidal signs in the legs. In conclusion, the clinical and laboratory features of this patient show that galactosialidosis may be considered in patients even in the absence of oligosacchariduria and that galactosialidosis should be regarded as a differential diagnosis in patients with neuropathic pain.

Objective: The aim of this study was to assess the expression of the interferon type I (IFN-I)-associated MxA protein in polymyalgia rheumatica (PMR) and temporal arteritis (TA)., Methods: Non-inflamed temporal artery biopsies from 11 PMR patients were compared with biopsies from 13 patients given other diagnoses. Coded sections were screened immunocytochemically for MxA protein, CD83, CD68, CD3, and S100 protein. Inflamed temporal artery biopsies from four patients with TA were also investigated., Results: Focal MxA expression was seen in non-inflamed arteries, more frequently in PMR than in controls (p = 0.0124). MxA expression was also more common in adventitial dendritic cells (DCs) in PMR (p = 0.0124). Activated adventitial DCs were detected in PMR. Focal MxA expression in the inflamed biopsies from the patients with TA was not related spatially to the inflammation., Conclusions: The expression of MxA protein in arteries from patients with PMR and TA shows that non-inflamed and inflamed vessel walls are influenced by IFN-I. Further studies are required to elucidate whether IFN-I plays a role in the initiation of PMR and/or TA, serving as a link between the innate and the adaptive immune responses, as in some other autoimmune disorders.

The aim of the study was to investigate T cell receptor (TCR) usage at the time of diagnosis of giant cell arteritis (GCA) and to estimate the degree of clonality of T-cells infiltrating the lesion. Seven patients with biopsy-proven giant cell arteritis were included in the study. Immunocytochemistry in biopsies from the temporal arteries and flow cytometric analysis of peripheral blood lymphocytes (PBL) was performed using monoclonal antibodies specific for CD3, CD4 and CD8 and 13 TCR Valpha and Vbeta gene segment products. The CDR3 fragment length polymorphism was assessed by gel electrophoresis of PCR-amplified TCR segments. The T lymphocytes were found to be concentrated to the adventitia rather than the media or intima. Six of the seven patients with GCA had expansions of T lymphocytes, expressing selected TCR V genes in the arterial wall. None of these expansions was found in PBL. The infiltrating T-cells were poly- or oligoclonal. In conclusion, the dominating part of the inflammatory infiltrate in GCA emanates from the adventitial microvessels. There is an uneven expression of TCR V genes by T lymphocytes in the inflammatory infiltrates as compared to peripheral blood T lymphocytes at the time of diagnosis, consistent with an antigen-driven immunological reaction in the arterial wall.

A girl with Hurler disease (MPS IH) underwent allogeneic stem cell transplantation at 13 months of age with her one HLA-B antigen mismatch mother as donor. The procedure was complicated by cerebral hemorrhage and a ventricular-peritoneal shunt device was inserted. Mild GVH reactions were rapidly reversed. One year after transplantation ventriculitis was suspected and the shunt was replaced by a ventricular drainage catheter. Antibiotics had no effect and graft-versus-host disease (GVHD) was diagnosed. All symptoms were reversed by prednisolone and cyclosporine. Increased albumin and pleocytosis in the cerebrospinal fluid (CSF) normalized concomitantly. Electron microscopy of the CSF sediment showed debris consisting of numerous complex aggregates of thin lamellae and electron dense fragments with a tight lamellar texture. Biochemical analysis of the CSF sediment proved that the debris contained galactosylceramide and sulfatide. The electron microscopic and biochemical findings were interpreted to represent stripping of central myelin as a result of subacute GVHD in the central nervous system and its desquamation from the brain parenchyma into the ventricular CSF through the post-hemorrhage defect. From reversal of the GVHD at 2 years of age until follow-up at 10 years of age the clinical condition remained stable with no recurrence or deterioration.

Objectives: HIV-1 infects the central nervous system (CNS) early in the course of infection. However, it is not known to what extent the virus evolves independently within the CNS and whether the HIV-RNA in cerebrospinal fluid (CSF) reflects the viral population replicating within the brain parenchyma or the systemic infection. The aim of this study was to investigate HIV-1 evolution in the CNS and the origin of HIV-1 in CSF., Materials and Methods: Longitudinally derived paired blood and CSF samples and post-mortem samples from CSF, brain and spleen were collected over a period of up to 63 months from three HIV-1 infected men receiving antiretroviral treatment and presenting with symptoms of AIDS dementia complex (ADC)., Results: Phylogenetic analyses of HIV-1 V3, reverse transcriptase (RT) and protease sequences from patient isolates suggest compartmentalization with distinct viral strains in blood, CSF and brain. We found a different pattern of RT and accessory protease mutations in the systemic infection compared to the CNS., Conclusions: We conclude that HIV-1 may to some extent evolve independently in the CNS and the viral population in CSF mainly reflects the infection in the brain parenchyma in patients with ADC. This is of importance in understanding HIV pathogenesis and can have implications on treatment of HIV-1 patients.

The rostral migratory stream (RMS) is the main pathway by which newly born subventricular zone cells reach the olfactory bulb (OB) in rodents. However, the RMS in the adult human brain has been elusive. We demonstrate the presence of a human RMS, which is unexpectedly organized around a lateral ventricular extension reaching the OB, and illustrate the neuroblasts in it. The RMS ensheathing the lateral olfactory ventricular extension, as seen by magnetic resonance imaging, cell-specific markers, and electron microscopy, contains progenitor cells with migratory characteristics and cells that incorporate 5-bromo-2'-deoxyuridine and become mature neurons in the OB.

Objective: As giant cell arteritis (GCA) progresses, newly formed microvessels are one of the main sites of leukocyte-endothelial cell interaction. Our aim was to stereologically map the distribution of microvessels in the temporal arterial wall and to assess their relationship to the degree of inflammation in GCA., Methods: Inflamed temporal arteries from 21 patients who fulfilled the American College of Rheumatology criteria for GCA were analyzed. Paraffin sections, stained with an antibody directed at vascular endothelium, were analyzed stereologically. The degree of inflammation and the surface of microvascular endothelium per volume (microm2/microm3) were assessed in 4 different layers of the arterial wall., Results: The degree of inflammation and of vascularization was greatest in the adventitia, smaller in the media, and smallest in the intima. A significant positive relationship was observed between the degree of inflammation and the degree of vascularization in the media and in the outer and inner layers of the intima. In 8 biopsies, the microvessels formed a prominent plexus in the intima without apparent connection with microvessels in the adventitia/media, and there were no signs of endothelial budding from the arterial lumen., Conclusion: Our results confirm that inflammation is a major determinant in neovascularization in GCA. Some new microvessels are formed by the budding of the adventitial vasa vasorum. The presence of intimal microvascular networks without apparent connection with microvessels in the media might indicate additional influence on neovascularization.

Stem cells generate neurons in discrete regions in the postnatal mammalian brain. However, the extent of neurogenesis in the adult human brain has been difficult to establish. We have taken advantage of the integration of (14)C, generated by nuclear bomb tests during the Cold War, in DNA to establish the age of neurons in the major areas of the human cerebral neocortex. Together with the analysis of the neocortex from patients who received BrdU, which integrates in the DNA of dividing cells, our results demonstrate that, whereas nonneuronal cells turn over, neurons in the human cerebral neocortex are not generated in adulthood at detectable levels but are generated perinatally.

Objective: To assess female sex hormone related variables in a group of women with biopsy positive giant cell arteritis and a control group., Methods: 49 women with biopsy positive giant cell arteritis, aged 50 to 69 years at the time of diagnosis, answered a questionnaire on hormonal and reproductive factors. The same questions were answered by a large population of women from the same geographical area in connection with routine mammograms. The results were tested statistically, using logistic regression analysis of each variable adjusted for age, and a multivariate logistic regression analysis including age and the variables which differed significantly between giant cell arteritis and controls., Results: From the multivariate logistic regression analysis, three independent variables were associated with an increased risk of having giant cell arteritis: smoking and being an ex-smoker (odds ratio (OR) = 6.324 (95% confidence interval (CI), 3.503 to 11.418), p<0.0001); body mass index (a reduction of 1.0 kg/m2 increased the risk by 10% (OR = 0.898 (0.846 to 0.952), p = 0.0003); and menopause before the age of 43 (OR = 3.521 (1.717 to 7.220), p = 0.0006)., Conclusions: There was a significant association between hormonal and reproduction related factors and the risk of developing giant cell arteritis in women given the diagnosis before the age of 70. The results suggest a possible role of oestrogen deficiency in the pathogenesis of giant cell arteritis. To confirm the results, an extended study will be needed, including women older than 70.

Objective: The epidemiology of giant cell arteritis (GCA) may indicate a pathogenetic relationship between GCA and female sex hormone metabolism; GCA is two to four times more common in women compared with men. Our previous analyses gave no support for the hypothesis that the pathogenesis of GCA should be related to somatic mutations in the estrogen receptor alpha (ERalpha) gene. The object of the present study was to investigate the size of the estrogen receptor beta (ERBeta), and the size and nucleotide sequence of the ERBeta gene in temporal arteries in GCA., Methods: The ERBeta protein was analyzed by Western blot technique and the ERBeta gene by RT-PCR and direct sequencing of the PCR product., Results: Western blot analysis revealed an ERBeta of normal size. There were no aberrations in size or nucleotide sequence in the ERBeta gene in the GCA patients., Conclusion: The present observations gave no support for the hypothesis that somatic mutations in the ERBeta gene should be involved in the pathogenesis of GCA.

Objectives: Dual pathology is reported in 5-30% of temporal lobe resections performed in pharmacoresistant epilepsy. Dual pathology may be of importance for surgical planning and also for the understanding of the pathogenesis of epilepsy. We describe the frequency of dual or multiple pathology, i.e. more than one histopathological diagnosis, in adults with temporal lobe resections., Material and Methods: Surgical specimens from 33 consecutive patients with resections including mesial as well as neocortical temporal structures were reviewed. All histopathological findings were recorded. Post-mortem specimens from 11 control subjects were also reviewed., Results: Dual or multiple pathology was found in almost half of the epilepsy patients (48%). Hippocampal sclerosis was found in 25 patients (76%), malformations of cortical development in 15 (46%), of which 12 (36%) were microdysgenesis, and low-grade tumours in seven (21%). Apart from mild gliosis, there were no histopathological changes in the control specimens., Conclusion: Dual or multiple pathology was a common finding in this group of adults with temporal lobe resections. In order to increase our understanding of how aetiological factors may combine in the development of seizures, we consider it relevant and important to report all histopathological findings in epilepsy surgery series.

The aim of the present study was to investigate the expression of TP53 (p53) and CDKN1A (CIP1; p21) in the arterial wall in giant cell arteritis (GCA). Cross-sections from 18 temporal artery biopsies displaying GCA and 8 control arteries were double-stained with monoclonal antibody directed at p53 or p21 on the one hand and alpha-smooth muscle actin, CD68 (macrophage) or CD3 (T-cell) on the other. Nuclear p53 was expressed in CD68-positive cells and smooth muscle cells in 16 of the 18 inflamed arteries. P21-positive nuclei were found in CD68-positive cells in 14 biopsies and in smooth muscle cells in all the specimens. All p53-positive giant cells also contained p21-positive nuclei. In the giant cells, immunopositive nuclei were mixed with negative ones. CD3-positive T-cells did not express p53 or p21. Only one p53-positive smooth muscle cell nucleus was found in the non-GCA controls and, compared with GCA, p21 expression was noted in few smooth muscle nuclei. The presence of p53 and p21 in the same types of cell in GCA indicates that the former protein is functional; p21 expression is induced by wild-type, functional p53 but not by its mutant form. The current observations suggest cellular stress in GCA, the nature of which requires further investigation.

Background: Iatrogenic nerve injury caused by heat from dissection instruments is a significant problem in many areas of surgery. The aim of the present study was to compare the risk of nerve injury for three different dissection instruments: monopolar and bipolar electrosurgery (ES) and an ultrasonically activated (US) instrument., Methods: The biceps femoris muscle was cut in a standard manner just adjacent to the sciatic nerve using monopolar ES, bipolar ES or US shears. A total of 73 functional experiments were conducted in which the nerve was isolated, divided proximally, and stimulated supramaximally in 37 anaesthetized rats. The electromyographic (EMG) potential was recorded distally before and after each experiment. Nerve dysfunction was defined as more than 10 per cent loss of the evoked EMG potential. Fifty-nine nerves were examined histologically after dissection with the different instruments. The extent of heat damage was determined in four nerves that were divided with ES bipolar scissors and five that were divided with US shears., Results: Reduction in the EMG potential was significantly more frequent in the monopolar ES group than in the US group. Morphological examination also showed significantly less nerve damage in the US group., Conclusion: US instruments may be safer than ES for dissection close to nerves., (Copyright (c) 2005 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd.)

Microdysgenesis is a microscopic malformation of cortical development characterized by heterotopic neurones and abnormal cortical architecture. It has been described in primary generalized and partial epilepsy. Its significance in epileptogenesis is controversial, partly due to lack of consensus of diagnostic criteria. Different terms have also been used for the malformation. Several quantitative studies have been performed of the histopathological aberrations associated with microdysgenesis. A majority of the studies have revealed an increased number of heterotopic neurones in specimens from epilepsy patients. However, the quantitative values given for abnormal numbers of white matter neurones vary greatly between studies and there is no consensus yet on quantitative criteria for microdysgenesis. There have also been conflicting results from studies correlating microdysgenesis with clinical data. Both favourable and worse outcome after epilepsy surgery have been reported in patients with increased numbers of white matter neurones and microdysgenesis. While some studies have shown earlier seizure onset and increased frequency of mental retardation in patients with microdysgenesis, others have not. Differences in inclusion criteria and definition might contribute to the contradictory results. There is some evidence that microdysgenesis could be important in epileptogenesis, but the mechanisms involved remain unknown and difficult to investigate. A consensus on what histopathological criteria to use for the diagnosis of microdysgenesis is needed to explore this further and enable comparisons between centres. There are advantages and disadvantages both with quantitative stereological and with qualitative assessments. It is necessary to evaluate these in the decision on diagnostic criteria, if possible taking both qualitative and quantitative aspects into account.

An eight-year-old girl with Aicardi syndrome (AIC) developed signs of increased intracranial pressure. A clinical and radiological investigation revealed a tumor in the posterior fossa, which was resected. The histopathological diagnosis was large-cell medulloblastoma. Eight months later, she died of a local recurrence, despite treatment with chemotherapy and radiotherapy according to a PNET protocol. In addition to the growth of a large-cell medulloblastoma at the location of the primary tumor and the meningeal spread of the tumor, the autopsy revealed major cortical and subcortical malformations of the brain. Various benign (e.g., plexus papillomas) and malignant tumors (angiosarcoma, embryonic carcinoma, and hepatoblastoma) have been reported in connection with Aicardi syndrome. A genetic analysis of AIC suggests that the mutation is localized on the distal part of the short arm of the X chromosome, an area that may be of importance for tumor development. This is the first report of a primary malignant brain tumor -- large-cell medulloblastoma -- in a patient with Aicardi syndrome.

Purpose of Review: This review summarizes current diagnostic assessments and therapeutic strategies in giant cell arteritis. Giant cell arteritis or temporal arteritis is a chronic vasculitis of large and medium-size vessels. Concurrent symptoms of proximal muscular ache and morning stiffness, polymyalgia rheumatica, are commonly seen. Recent investigations support the contention that polymyalgia rheumatica and temporal arteritis are two different expressions of the same underlying vasculitic disorder., Recent Findings: The symptomatology of giant cell arteritis is quite varying. Recently a frequent occurrence of audiovestibular manifestations was demonstrated, which should be actively searched for in the clinical investigation. Although color Doppler ultrasound, MRI, and positron emission tomography have illustrated the widespread nature of giant cell arteritis, none of these techniques may currently replace temporal artery biopsy. Biopsy of the superficial temporal artery is a safe and simple procedure, and remains the gold standard for the diagnosis of giant cell arteritis. The importance of long biopsies and meticulous histologic examination using sub-serial sectioning is emphasized. Numerous recent publications confirm the low diagnostic yield of a second, contralateral biopsy. Corticosteroids remain the cornerstone in the treatment of giant cell arteritis. Although steroid treatment promptly eliminates symptoms of systemic inflammation, its effect on inflammatory morphology is delayed. Consequently, there is a need for new therapeutic strategies. The potential role of aspirin has recently been implicated.

Microdysgenesis is a microscopic malformation of cortical development (MCD) associated with epilepsy, but its significance in epileptogenesis is debated. This is partly since the histopathological aberrations associated with microdysgenesis can also be found in normal brains. We here report a method for objective analysis of one criterion for microdysgenesis, irregular cortical nerve cell distribution. Tissue from the lateral temporal lobe from two epilepsy patients was compared with tissue from two post-mortem controls. An expansion/shrinkage factor was calculated to determine the change in tissue size during cutting and mounting. Neurons were identified and the positions of their nucleoli were marked and stored. The spatial distribution of neurons was analysed using distance to nearest neighbouring neuron and Voronoi tessellation. Specimens from the epilepsy patients expanded markedly during mounting compared with controls. Epilepsy specimens had shorter mean distances to nearest neighbour than controls and smaller Voronoi tessellation areas than controls. Both measurements suggest more densely packed neurons in epilepsy specimens. This pilot study describes a new objective method for identification of cortical neurons and their spatial distribution. Voronoi tessellation and distance to nearest neighbouring neuron might provide robust methods for objective analysis of cortical nerve cell distribution. The yield of such comparisons might be improved if each cortical layer is analysed separately.

Objective: The incidence of giant cell arteritis (GCA) increases with age. The aim of the present study was to investigate whether the increasing incidence of biopsy-proven GCA in Göteborg, Sweden, could be explained in terms of a change in the age composition of the general population., Methods: All cases of biopsy-verified GCA between 1976 and 1995 were recorded. The annual incidence was calculated for women and men aged 50 yr or older and its relationship with the age composition of the general population was tested statistically., Results: There was a significant positive correlation between age and the risk of developing GCA. In the general population, there was a shift towards higher age; in 1976, the mean age of people 50 yr or older was 63.2 (men) and 65.0 (women), whereas in 1995 it was 65.0 (men) and 68.1 (women). After compensating for this, the incidence of biopsy-proven GCA still increased significantly. Moreover, for women aged 50 yr or older, the risk of developing the disease increased more among younger subjects than older ones., Conclusions: The increase in the incidence of biopsy-proven GCA between 1976 and 1995 could not be explained merely in terms of the increasing age of the general population. It is most probably related to an increase in the influence of other factors.

Giant cell arteritis (GCA) is a chronic systemic vasculitis with a marked female predominance and restriction to old age. The disease process distinctly targets large and medium sized arteries, preferentially the aorta and its extracranial branches. Morphological observations indicate that the age and sex distribution of GCA is related to the occurrence of degenerative changes in the arterial wall. GCA is not a truly infectious vasculitis. However, an infection might be a triggering factor. Different centres report an increase in GCA incidence, but annual fluctuations have not been shown to be statistically significant. However, significant seasonal variations have been observed by several groups. The mortality is not increased in adequately treated patients. Although, alternative steroid-sparing agents have been proposed, corticosteroids are still the first treatment choice.

The effect of postoperative housing conditions on functional outcome and brain-derived neurotrophic factor (BDNF) gene expression was evaluated 1 month after a distal ligation of the right middle cerebral artery (MCA) in spontaneously hypertensive rats. Two days postoperatively the rats were randomized into four groups; individually housed with no equipment (deprived group), individually housed with free access to a connected running wheel (running group), housed together in a large cage with no equipment (social group) or in the same size of cage furnished with bars, chains and various things to manipulate (enriched group). The enriched rats had significantly higher scores when crossing a rotating horizontal rod than deprived and running rats. The social group performed significantly better than the deprived group. The BDNF gene expression in the ipsi- and contralateral cortex, thalamus, hippocampus and cerebellum did not significantly differ between the groups. The weight of the adrenal glands was significantly increased in running rats suggesting that postischemic running may be stressful. We conclude that the beneficial effect of postischemic environmental enrichment is likely to be a combination of social and various physical activities, and that BDNF gene expression 1 month after a cortical infarct did not correlate with functional outcome.

The purpose of this work was to relate clinical neuropsychiatric findings to histopathological diagnoses and seizure outcome in a retrospective study of 16 children undergoing temporal lobe resections due to medically intractable epilepsy. These children constitute a heterogeneous group in which neuropsychiatric symptoms were common. The results of this study indicate a correlation between malformations of cortical development, less chance of seizure freedom, and neuropsychiatric problems in children with pharmacoresistant temporal lobe epilepsy. It is important to include neuropsychiatric assessments pre- and postoperatively and to inform parents that symptoms of autism spectrum disorders may or may not be improved after epilepsy surgery.

Microdysgenesis is a subtle malformation, which is often found in specimens from epilepsy surgery. It is, however, not clear whether the changes are focal or diffuse. A recent autopsy case offered an opportunity to investigate whether microdysgenesis found after temporal lobe surgery was focal or widespread in the brain. The entire brain of a 20-year-old patient who died suddenly and unexpectedly was examined histologically. Microdysgenesis had previously been diagnosed after a left temporal lobectomy performed because of therapy-resistant seizures. A light microscopic examination was performed on specimens stained with Luxol-fast blue-cresyl violet and polyclonal antibodies to glial fibrillary acidic protein. Widespread microdysgenesis with irregular nerve cell distribution in the cortex and an increased number of nerve cells in cortical layer I and in the white matter was found in the right temporal and parietal lobes and bilaterally in the frontal and occipital lobes. The post-mortem examination confirmed the previous diagnosis of microdysgenesis and showed that the changes were widespread in a patient who was operated on because of focal epilepsy.

In our RT-PCR screen for cytokine expression in human brain tumors we discovered increased levels of oncostatin M (OSM), ciliary neurotrophic factor (CNTF) and leukemia inhibitory factor (LIF), all belonging to the interleukin-6 (IL-6) cytokine family, in most of the tumors. The expression of these cytokines in normal adult brain tissue was found to be very low or below detection limit. OSM expression was elevated in most of the tumors and immunohistochemistry analysis showed that the tumor cells contained OSM in their cytoplasm, suggesting they produce this factor. Overexpression of OSM has not previously been reported in primary human brain tumors. The IL-6 cytokine family acts through a common gp130 receptor subunit that activates the JAK/STAT signaling pathway and therefore they have been suggested to have overlapping effects. Tissue inhibitor of metalloproteinase-1 (TIMP-1), matrix metalloproteinase 1 (MMP-1) and MMP-3 and IL-6 have been reported to be regulated by OSM. IL-6 was low or absent in the tumors. TIMP-1, MMP-1 and MMP-3 was expressed in most tumors but with no strict correlation to OSM levels.

Objective: To investigate the age and sex distribution of calcifications of the internal elastic membrane (IEM) in temporal arteries., Methods: Calcifications of the IEM were assessed light-microscopically in temporal arteries from 40 women and 21 men, aged 51 or more, who were known not to have giant cell arteritis (GCA). Their relation to age and the difference between women and men were tested statistically., Results: The IEM calcifications differed morphologically from the calcifications in Mönckeberg's mediosclerosis and atherosclerosis. They increased significantly with age and were 2.62 times more common in women than men., Conclusion: Previous morphological studies indicate that the inflammatory process in GCA is initiated by a foreign-body, giant-cell attack on calcifications of the IEM. The present study showed that IEM calcifications in non-GCA controls show an age and sex distribution similar to that of GCA morbidity. The results may indicate that the presence of IEM calcifications in the general population influences the age and sex distribution of GCA. Furthermore, the findings support the hypothesis that the calcifications, although not disease specific, may play a pathogenetic role in the latter.

We report on two sisters with an infantile onset of dyskinetic movements, tonic spasms, seizures and apneic spells. The condition deteriorated to a hypotonic "burnt out" stage by the age of 3 years in the older sister and to a stable dyskinetic condition by the age of 2.5 years in the younger one. A skin biopsy from the older sister revealed myelinated nerve fibers crowded with neurofilaments. The extensive investigation for neurometabolic disorder, magnetic resonance imaging of the brain, and ophthalmological and neurophysiological examinations were not especially revealing. The older sister died at the age of 3 years. The autopsy revealed no apparent loss of nerve cells in the brain and no sign of storage disease. However, silver-stained coarse granules, immunopositive for neurofilament polypeptide, were found around nerve cell bodies in the cortex and in the basal ganglia. Electron microscopy revealed perineuronal membrane-bound profiles filled with filaments. Silver-stained axonal torpedoes were found in the cerebellum, but there were no spheroids. The substantia nigra, the locus ceruleus and the nucleus basalis of Meynert showed extensive perineuronal and perivascular swelling. Homovanillic acid was severely reduced, while 5-hydroxyindoleacetic acid and hydroxymethylphenyl glycol were normal in the cerebrospinal fluid of the severely affected, autopsied case. The two cases are considered to represent a new form of infantile neuroaxonal dystrophy, characterized by the degeneration of perineuronal terminals in the cerebral cortex and in the basal ganglia, as well as by axonal degeneration in the cerebellum and peripheral nerves.

Objective: Giant cell arteritis (GCA) predominantly affects postmenopausal women. Estrogen receptor alpha (ER alpha) accumulates in the cytoplasm of smooth muscle cells, activated mononuclear inflammatory cells and giant cells in the temporal arteries of GCA patients, as well as in smooth muscle cells in arteries from non-GCA controls. The aim of this study was to analyse whether this accumulation is related to structural aberrations in the ER alpha mRNA leading to a change in protein structure., Methods: Total RNA was extracted from inflamed temporal artery tissue in two GCA patients and from non-inflamed arteries in two non-GCA controls. Products from the nested RT-PCR of the cDNA were cloned and plasmid inserts of 20 different clones from each case were investigated using nucleotide sequence analysis., Results: A total of eight different types of transcripts lacking parts of the ER alpha mRNA were detected. Seven of these could be explained by alternative splicing. There were no significant differences between the GCA patients and the non-GCA controls in terms of the number of transcript variants., Conclusion: The accumulated cytoplasmic ER alpha in temporal arterial tissue from elderly persons appears mainly to be of wild type. The main structural changes in the ER alpha mRNA may be due to alternative splicing. Somatic mutations of the ER alpha gene appear to be rare and it is therefore unlikely that they are involved in the pathogenesis of GCA.

Giant cell arteritis (GCA) is a chronic inflammatory disorder targeting large and medium-sized arteries, which predominantly affects postmenopausal women. Its high incidence in populations with Scandinavian lineage, some familial accumulation, and the association with the HLA-DR4 haplotype indicate a genetic predisposition. Epidemiological observations, as well as the symptomatology, may indicate an infectious origin, but so far GCA has not been shown to be a truly infectious form of vasculitis. Immunological research indicates an antigen-driven disease with local T-cell and macrophage activation in the vessel wall. Morphologically, the inflammatory process appears to be initiated by a foreign-body giant-cell attack on calcified internal elastic membrane in arteries and on calcified atrophic parts of the aortic media. The ensuing diffuse chronic inflammation leads to vessel dilatation and extensive intimal thickening. The latter, which relates to the production of promoting factors by the inflammatory cells, causes arterial stenosis and ischemic complications. The possible role of female sex hormones in GCA requires further investigation. Mononuclear and giant cells in GCA display the cytoplasmic accumulation of estrogen receptor (ER) alpha. Cytoplasmic ER-alpha is also seen in media smooth-muscle cells in GCA and in non-GCA controls, but nucleotide sequence analysis of the ER-alpha gene revealed no differences between GCA patients and controls. In the future, comprehensive morphological, cell biological and immunological research will be required for a better understanding of the complex etiology and pathogenesis of GCA.

Objective: To investigate morphometrically the relationship between the degree of inflammatory reaction and arterial cross-sectional dimensions in giant cell arteritis (GCA)., Methods: The media and intima of cross-sectioned inflamed arteries from GCA patients were outlined. The media circumference and the media and intima cross-sectional areas were measured. The two segments in every biopsy displaying the least and most widespread media inflammation were compared, using a paired Student's t-test. Moreover, paired comparisons were made of the intima area in inflamed and noninflamed sectors in single cross-sections., Results: The segment in each biopsy showing the most widespread media inflammation had the largest circumference and volume of media and intima; the intima cross-sectional area increased disproportionately. The intima was thickest in inflamed sectors in single cross-sections., Conclusion: The close spatial correlation between inflammatory media infiltration and the marked intimal expansion supports the contention that promoting factors produced by inflammatory cells play a pathogenetic role in GCA.

The light-microscopic, electron-microscopic and immunocytochemical characteristics of giant cell arteritis (GCA) have been investigated in a number of studies on temporal arteries. Arterial atrophy and calcification of the internal elastic membrane appear to be prerequisites for the evolution of the inflammatory process. Foreign body giant cells form close to calcifications, apparently without connection with other inflammatory cells and probably by the fusion of modified vascular smooth muscle cells. The foreign body giant cells attack the calcifications. Lymphocytes accumulate around them and may be found in pockets in their cell surface. This focal reaction is found in atrophic, calcified arterial segments in a minority of inflamed temporal artery biopsies. More commonly seen is a diffuse mononuclear attack of the vessel wall in atrophic as well as non-atrophic segments which leads to severe arterial dilatation. Langhans giant cells form by the fusion of macrophages in the diffuse inflammatory infiltrate. The fact that the diffusely inflamed arteries are markedly widened compared to the focally inflamed vessels suggests that the inflammatory process starts as a focal foreign body giant cell reaction directed at calcifications which in turn initiates a more diffuse and widespread inflammation.

Objective: The aim of this work was to study changes in the incidence of biopsy-proven giant cell arteritis (GCA) over a period of 20 yr in Göteborg, Sweden., Methods: All cases of biopsy-verified GCA between 1976 and 1995 were included in the study. The annual incidence was calculated for the whole material, for women and men separately, and its fluctuations were tested statistically. In addition, the monthly variation during the last 9 yr could be statistically analysed for the whole material., Results: In total, 665 patients were diagnosed with biopsy-verified GCA during the 20 yr period. The average annual incidence was 22.2/100000 inhabitants over 50 yr of age (women 29.8, men 12.5). The annual incidence increased significantly with time (P<0.001) for both men and women. Statistical analysis did not reveal any cyclic fluctuation in the annual incidence (P=0.26), while the monthly number of positive biopsies showed significant fluctuation with peaks in late winter and autumn (P=0.041)., Conclusions: The annual incidence of biopsy-positive GCA increased during the years 1976 through 1995. The significant seasonal variation, as well as considerable variation in annual incidence, might be due to the influence of exogenous triggering factors, such as infections. Further support for an exogenous aetiology, in terms of a statistically significant cyclic fluctuation of the annual incidence, was not found, however.

Objective: Giant cell arteritis (GCA) is a chronic form of vasculitis which predominantly affects women over 50 years of age. The aim of this study was to analyse the presence of estrogen receptor alpha (ER) in the temporal arteries of patients with GCA., Methods: Inflamed temporal artery biopsies from 43 GCA patients were stained with monoclonal antibodies to two different segments of the ER and compared with non-inflamed arteries from age- and sex-matched controls who had not received a clinical diagnosis of GCA. The protein that was extracted from 4 GCA-positive biopsies and 4 non-GCA controls was analysed using the Western blot method with a monoclonal antibody to ER. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis using primer pairs specific to ER-cDNA was performed on the total RNA from 4 GCA-positive biopsies and 4 non-GCA controls., Results: The inflamed arteries expressed distinct cytoplasmic immunoreactivity to ER in activated mononuclear inflammatory cells and in giant cells. Biopsies from GCA patients and controls displayed cytoplasmic ER positivity in smooth muscle cells. Western blot analysis revealed two bands corresponding to approximately 64 and 54 kDa, respectively, in the inflamed arteries and controls. In the inflamed biopsies and non-GCA controls, RT-PCR analysis revealed a strong band corresponding to approximately 670 bp, as expected, and a weaker band corresponding to approximately 440 bp., Conclusion: In inflamed arteries from GCA patients, smooth muscle cells, activated mononuclear inflammatory cells and giant cells express cytoplasmic ER. Non-inflamed control arteries also express cytoplasmic ER in smooth muscle cells. The accumulation of cytoplasmic ER may suggest the involvement of estrogen not only in GCA but also in normal vascular aging. The results justify further investigations into the pathogenetic roles of estrogen metabolism in GCA.

Malformations of cortical development are commonly associated with epilepsy. In the first 139 consecutive patients in the Göteborg epilepsy surgery series, parenchymal malformations were found in 56. 1% of the children and in 23.1% of the adults. Microdysgenesis (MDG), which was the most common parenchymal malformation, was found in 35. 1% of the children and in 16.7% of the adults. The aim of this study was to identify clinical characteristics of patients with MDG. Mental retardation was found to be significantly more common in patients with major parenchymal malformations and in patients with MDG compared with patients without parenchymal malformations. Patients with major parenchymal malformations as well as patients with MDG also had a significantly earlier onset of seizures than patients without parenchymal malformations, also when adjusting for mental retardation. Patients with MDG were in these clinical aspects shown to closely resemble patients with major malformations. These findings suggest that MDG is a pathoanatomical entity of clinical relevance, with implications both in mental retardation and in epileptogenesis.

High blood levels of glucocorticoids are associated with increased mortality, confusion and poor functional outcome in stroke patients. It has been proposed that inhibition of glucocorticoids in acute stroke might be beneficial, but experimental data are conflicting and no long-term follow-up study has been reported. We have studied whether pre- or postoperative administration of metyrapone, a steroid synthesis inhibitor, can influence long-term outcome after ligation of the right middle cerebral artery (MCA) distal to the striatal branches in hypertensive rats. Metyrapone (200 mg/kg) was administered either 30 min before or 1, 12 and 24 h after MCA occlusion. Limb placements and ability to traverse a rotating pole were evaluated pre- and postoperatively. Infarct size, histology and GFAP immunoreactivity were evaluated on 5 microm coronal sections from brains perfused in situ 4 weeks after the ischemic event. Pretreatment did not influence outcome, whereas postoperative administration of metyrapone significantly increased infarct volume (P < 0.05). Post-treated rats performed significantly worse than vehicle-treated rats on the rotating pole 3 weeks after the operation (P < 0.05). Our results do not support the hypothesis that inhibition of glucocorticoid synthesis improves outcome after cerebral ischemia., (Copyright 1999 Lippincott Williams & Wilkins)

The aim was to study if exposure to an enriched environment influenced graft-host interface and neuronal markers in neocortical grafts implanted in cortical infarct cavities 3 weeks after distal ligation of the middle cerebral artery in adult hypertensive rats. Half the rats were exposed to an enriched environment for 2 h daily 5 days a week starting 1 week after the arterial ligation. The brain was fixed by perfusion 4 weeks postgrafting. The immunoreactivity to glial fibrillary acidic protein, microtubule associated protein 2, and synaptophysin was studied in coronal paraffin-embedded sections. A distinct glial border separated the infarct cavity from the surrounding brain in sham-transplanted rats. Most grafts filled the larger part of the infarct cavity. In 8 of 18 transplants, 4 in each experimental group, part of the transplants protruded through the thin glial membrane that delineated the transplant-host interface into the adjacent host brain tissue. Microtubule associated protein 2 immunostained sections indicated bridging of dendrites in the host-transplant interface. Synaptophysin immunoreactivity was significantly higher in grafts than in contralateral cortex. However, graft morphology and neuronal marker immunoreactivity did not differ between rats housed in standard and activity stimulating cages.

The present study relates clinical and radiological data to histopathological diagnoses in the first 139 patients (children and adults) in the Göteborg Epilepsy Surgery series. Temporal lobe resections were most common (54.0%) followed by frontal lobe (18.0%) and multilobar resections (11.5%). All histopathological specimens were re-evaluated in connection with this study. Parenchymal malformations and atrophic-gliotic lesions were the most common histopathological findings. Microdysgenesis was more common than major malformations (24.5% versus 11.5%). When the MRI scans were blindly re-evaluated the MRI findings correlated with histopathological diagnosis in all of the vascular malformations, in 77.8% of the tumours, in 76.5% of the cases with hippocampal sclerosis but only in 28.6% of the major cortical development malformations. Hemispherectomies carried the best seizure outcome prognosis followed by temporal lobe resections (75.0% versus 57.3% seizure free 2 years after surgery). Vascular malformations carried the best, and microdysgenesis the worst prognosis (76.9% versus 39.4% seizure free).

Study Design: Application of autologous nucleus pulposus on nerve roots and treatment with local application of lidocaine in the pig., Objectives: Studies of the effects of lidocaine on nucleus pulposus-exposed nerve roots., Summary of Background Data: Nerve root infiltration may improve radicular symptoms beyond the pharmacologic duration of local anesthetics, but the mechanisms for this effect are not known., Methods: Nucleus pulposus was harvested from a lumbar disc and placed onto the sacrococcygeal cauda equina in pigs. In Series 1, early lidocaine treatment of nucleus pulposus-induced nerve root injury, pigs received 2% lidocaine (n = 5) or saline (n = 5) before and after surgery. Nerve conduction velocity and histologic appearance were studied after 3 days. In Series 2, delayed lidocaine treatment of nucleus pulposus-induced nerve root injury, after 7 days 2% lidocaine was administered epidurally to nucleus pulposus-exposed (n = 4) and -nonexposed (n = 4) nerve roots. Nerve conduction velocity, muscle action potentials, and histologic appearance were assessed., Results: In Series 1, early treatment with lidocaine limited the reduction in nerve conduction velocity. The epidural inflammation was less in lidocaine treated animals. In Series 2, nerve conduction velocity was lower in nucleus pulposus-exposed animals than in nonexposed animals. The initial reduction of nerve conduction velocity and muscle action potential was similar between the groups, but the recovery of muscle action potential was slower and less complete in nucleus pulposus-exposed nerve roots. There was minimal histologic nerve injury in both series and in both protocols., Conclusions: Early treatment with lidocaine may reduce nucleus pulposus-induced nerve root injury. Lidocaine induced a delayed recovery in nerve roots exposed to nucleus pulposus. Further studies are needed to clarify the therapeutic effects of nerve root infiltration and the pathophysiology of nucleus pulposus-induced nerve root injury.