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Abstract Current evidence suggests an analgesic role for the spinal cord action of general anesthetics; however, the cellular population and intracellular mechanisms underlying anti-visceral pain by general anesthetics still remain unclear. It is known that visceral nociceptive signals are transmited via post-synaptic dorsal column (PSDC) and spinothalamic tract (STT) neuronal pathways and that the PSDC pathway plays a major role in visceral nociception. Animal studies report that persistent changes including nociception-associated molecular expression (e.g. neurokinin-1 (NK-1) receptors) and activation of signal transduction cascades (such as the protein kinase A [PKA]-c-AMP-responsive element binding [CREB] cascade)-in spinal PSDC neurons are observed following visceral pain stimulation. The clinical practice of interruption of the spinal PSDC pathway in patients with cancer pain further supports a role of this group of neurons in the development and maintenance of visceral pain. We propose the hypothesis that general anesthetics might affect critical molecular targets such as NK-1 and glutamate receptors, as well as intracellular signaling by CaM kinase II, protein kinase C (PKC), PKA, and MAP kinase cascades in PSDC neurons, which contribute to the neurotransmission of visceral pain signaling. This would help elucidate the mechanism of antivisceral nociception by general anesthetics at the cellular and molecular levels and aid in development of novel therapeutic strategies to improve clinical management of visceral pain.

Ruptured vertebrobasilar dissecting aneurysms require urgent, often challenging treatment as they have with a high re-hemorrhage rate within the first 24 hours. The patient is a 57-year-old woman who presented with severe-sudden onset headache. Further work up showed a ruptured dissecting aneurysm of the caudal loop of the posterior inferior cerebellar artery (PICA) with associated narrowing distally, in the ascending limb. The aneurysm was immediately occluded with a Woven Endobridge (WEB) device (MicroVention, Tustin, CA, USA) while flow diversion treatment of the diseased ascending limb was postponed. Follow-up angiography three months later showed complete occlusion of the aneurysm, as well as healing of the diseased distal vessel, obviating the need for further intervention. WEB embolization of a ruptured dissecting posterior circulation aneurysm provided an excellent outcome for this patient.

Objective: To determine the impact of the 2019 novel coronavirus disease (COVID-19) pandemic on operative case volume in 8 U.S. neurosurgical residency training programs in early 2020 and to survey these programs regarding training activities during this period., Methods: A retrospective review was conducted of monthly operative case volumes and types for 8 residency programs for 2019 and January through April 2020. Cases were grouped as elective cranial, elective spine, and nonelective emergent cases. Programs were surveyed regarding residents' perceptions of the impact of COVID-19 on surgical training, didactics, and research participation. Data were analyzed for individual programs and pooled across programs., Results: Across programs, the 2019 monthly mean ± SD case volume was 211 ± 82; 2020 mean ± SD case volumes for January, February, March, and April were 228 ± 93, 214 ± 84, 180 ± 73, and 107 ± 45. Compared with 2019, March and April 2020 mean cases declined 15% (P = 0.003) and 49% (P = 0.002), respectively. COVID-19 affected surgical case volume for all programs; 75% reported didactics negatively affected, and 90% reported COVID-19 resulted in increased research time. Several neurosurgery residents required COVID-19 testing; however, to our knowledge, only 1 resident from the participating programs tested positive., Conclusions: This study documents a significant reduction in operative volume in 8 neurosurgery residency training programs in early 2020. During this time, neurosurgery residents engaged in online didactics and research-related activities, reporting increased research productivity. Residency programs should collect data to determine the educational impact of the COVID-19 pandemic on residents' operative case volumes, identify deficiencies, and develop plans to mitigate any effects., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Introduction The polyaxial head pedicle screw-rod system is a commonly used spinal instrumentation technique to achieve stabilization, deformity correction, and bony fusion. We present a novel plate-based pedicle screw system (UNIMAX TM ) that can be used for multi-level instrumentation with potential advantages for selected applications. Methods Bilateral titanium monoaxial pedicle screws are linked at each level by robust transversely oriented cross plates forming ring constructs capable of rigid triangulation at each level. The cross plates are then interconnected by sagittally oriented rigid plates situated medial to the screw heads. Biomechanically, the construct was tested for quasi-static torsion and fatigue in axial compression. The system is approved by the Food and Drug Administration (FDA). The system and case examples are presented showing its potential advantages. Results The quasi-static torsion, the mean for the angular displacement, torsional stiffness, and torsional ultimate strength was 2.5 degrees (SD ± 0.8), 5.3 N-m/mm (SD ± 0.7), and 21.6 N-m (SD ± 4.4). For the fatigue in axial compression, the closed ring construct failed when the applied load and bending moment were ≥ 1500 N and ≥ 60 N.m. This system maximizes the construct rigidity, allows easy extension to adjacent levels, and can be incorporated intuitively into practice. The ring construct with triangulation at each level, together with its biomechanical robustness, predicts a high pullout resistance. It requires an open posterior approach incompatible with minimally invasive techniques. Conclusion This system may have advantages over the screw-rod systems in carefully selected situations requiring extra rigidity and high pull-out strength for complex reconstructions, sagittal and/or coronal correction, patients with poor bone quality, revisions, and/or extension to adjacent levels., Competing Interests: Madhavan Pisharodi is the owner of the patent of the device described in this article, (Copyright © 2020, Pisharodi et al.)

Glycerol rhizotomy was originally described as an initial surgical treatment for trigeminal neuralgia after the failure of medical therapy. Here we describe its use as a salvage procedure, typically after failure of multiple other modalities including microvascular decompression, stereotactic radiosurgery, and/or other percutaneous procedures. Foramen ovale cannulation as a "salvage procedure" may be complicated by lack of cerebrospinal fluid (CSF) return despite adequate cannulation of the foramen ovale, making conventional fluoroscopic confirmation of adequate needle placement less certain. In this article, we describe the application of intraoperative CT, fused with high-resolution preoperative CT/MRI for neuronavigation to accurately cannulate the foramen ovale and Meckel's cave for glycerol rhizotomy. Intraoperative CT, again fused with high-resolution preoperative CT and MRI studies, was then used to confirm accurate trajectory through the foramen ovale and the adequate location of the needle tip in Meckel's cave before injecting glycerol. We present our initial experience with 14 patients who underwent glycerol rhizotomy by these techniques depending on intraoperative CT. It appears that intraoperative CT-guided neuronavigation provides a practical, reliable, and accurate route to the foramen ovale and aids in the confirmation of adequate needle placement even when there is a lack of CSF return. These methods may be especially useful for difficult cannulations typical in salvage procedures. In an era of feasible intraoperative guidance, with advanced stereotactic planning software allowing the fusion of intraoperative CT with high-resolution preoperative CT and MRI datasets, these techniques can be applied to foramen ovale cannulation for glycerol rhizotomy without major modification., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2020, Thatikunta et al.)

Punctate midline myelotomy (PMM) has been successfully applied clinically in humans for the relief of intractable visceral pain. The operation is thought to work by interrupting the postsynaptic dorsal column pathway (PSDC) of the spinal cord. In fact, PMM was developed specifically for that purpose after it was demonstrated in rats that the PSDC conveyed about 90% of the visceral pain information to the thalamus. The application of PMM also to the problem of severe intractable back or spine pain was never tested, and it has never been established whether the PSDC pathway relates only to visceral pain or whether there may be a broader involvement with pain affecting structures of embryological midline origin, perhaps including the spine. Retrospective analyses of decades of results from various attempted myelotomy procedures in man for the relief of pain are consistent with the notion that the common element crucial to the successful midline or visceral pain relief was the interruption--even incomplete--of the PSDC pathway. Herein, we present evidence from a rat model of lumbar facet pain that interruption of the PSDC significantly reduces pain responses. The implications for the possible treatment of severe intractable spine pain in man are discussed., Competing Interests: The authors have declared that no competing interests exist.

The authors report a case of an infant girl with macrocephaly-cutis marmorata telangiectatica congenita (Macrocephaly-CMTC). This patient presented with developmental delay, mild subcostal retractions, and occasional apneic spells. An MRI demonstrated mild to moderate lateral ventricle hydrocephalus, left hemi-megalencephaly, and left cerebellar tonsillar herniation with full occlusion of the cisterna magna. Her foramen magnum was narrowed, measuring 17.5mm in transverse diameter. This value was significantly below the 50th percentile for age, which is 23.5mm. Together, these findings were suggestive of cervicomedullary cord compression, concerning for sudden death. The patient underwent posterior fossa decompression by suboccipital craniectomy and cervical laminectomy. Initially due to hypertrophy and paralysis of the left true and false vocal cords, endotracheal intubation was not achieved, requiring tracheostomy tube placement. To our knowledge this is the first report of apnea in a patient diagnosed with M-CMTC, likely due to cervicomedullary cord compression and perhaps exacerbated by unilateral laryngeal hypertrophy. M-CMTC is a newly-described hemi-hypertrophy syndrome affecting the neurodevelopment of affected children. The authors emphasize airway obstruction secondary to unilateral hypertrophy of the vocal cords in addition to brainstem compromise as a consideration for the etiology of apnea in M-CMTC patients presenting with signs and symptoms of cervicomedullary cord compression.

Object: Arachnoid cysts are congenital lesions that arise during development by splitting of the arachnoid membrane. Large cysts can be adjacent to CSF pathways causing a marked midline shift and hydrocephalus. The association between a large arachnoid cyst and hydrocephalus has been commonly described as being due to a mass effect, but these previous reports have not focused closely on any associated intraventricular abnormalities., Methods: Seven patients who were previously treated with a cystoperitoneal shunt presented with shunt failure, hydrocephalus, and/or cyst expansion. All of these patients had giant arachnoid cysts extending to the periventricular region from the original site, which was the sylvian fissure in 4 patients, and the suprasellar cistern, quadrigeminal cistern, and interhemispheric fissure in 1 patient each. Endoscopic exploration of the ventricular system and cyst fenestration was then performed in all patients., Results: The endoscopic findings were obstruction of the cerebral aqueduct by a membrane not related to the cyst in 5 patients, occlusion of the foramen of Monro in 6, septum pellucidum hypoplasia in 2, and occlusion of the cerebral aqueduct by a quadrigeminal arachnoid cyst in 1. Endoscopic procedures performed were septum pellucidum fenestration and/or foraminoplasty in 5 patients, aqueductoplasty in 2, endoscopic third ventriculostomy in 5, fenestration of the lamina terminalis in 1, and direct cystocisternostomy in 1. After the endoscopic procedure, signs and symptoms of increased intracranial pressure and hydrocephalus improved in all patients, with a reduction in size of the cyst and the ventricle., Conclusions: Ventricular abnormalities contributing to hydrocephalus may be associated with arachnoid cysts. These abnormalities may more likely reflect a common origin than a casual relation. Foramen of Monro stenosis and cerebral aqueduct occlusion associated with an arachnoid cyst can be more frequent than has been previously believed. In cases of periventricular giant arachnoid cysts, endoscopic exploration is a good alternative for examining the ventricular system and identifying and treating CSF obstructions caused by and/or related to arachnoid cysts.

Object: Clipping of complex cerebral aneurysms often requires temporary vessel occlusion. The risk of stroke, however, increases exponentially with occlusion time. The authors hypothesized that prolonged temporary occlusion might be tolerated if the occluded vessels were perfused with cold physiological saline solution (CPSS). A low-flow perfusion rate would permit surgical manipulation of an aneurysm distal to the occlusion., Methods: To test this hypothesis, the authors temporarily occluded the middle cerebral artery (MCA) with an endovascular catheter in 6 rats. Three animals, the treatment group, were perfused with 5-ml CPSS/hour through the occluding endovascular catheter into the MCA, and the other 3 served as an ischemic control group. In both groups, the catheter was removed after 90 minutes of occlusion. The brain temperature was monitored with a stereotactically placed probe in the caudate-putamen in 2 separate experimental groups (11 animals)., Results: Magnetic resonance imaging perfusion scanning during vessel occlusion confirmed similar reduction of cerebral blood flow during MCA occlusion in both the simple-occlusion and perfusion-occlusion groups. Magnetic resonance imaging diffusion scans performed 24 hours after temporary occlusion revealed infarcts in the ischemic control group of 138.3 +/- 28.0 mm(3) versus 9.9 +/- 9.9 mm(3) in the cold saline group (p < 0.005). A focal cooling effect during perfusion with CPSS was demonstrated (p < 0.05)., Conclusions: Prolonged temporary cerebral vessel occlusion can be tolerated using superselective CPSS perfusion through an occluding endovascular catheter into the ischemic territory. This technique could possibly be applied in neurosurgery practice to the management of complex intracranial aneurysms.

Trigeminal nerve fibers in nasal and oral cavities are sensitive to various environmental hazardous stimuli, which trigger many neurotoxic problems such as chronic migraine headache and trigeminal irritated disorders. However, the role of JNK kinase cascade and its epigenetic modulation of histone remodeling in trigeminal ganglion (TG) neurons activated by environmental neurotoxins remains unknown. Here we investigated the role of JNK/c-Jun cascade in the regulation of acetylation of H3 histone in TG neurons following in vitro stimulation by a neuro-inflammatory agent, mustard oil (MO). We found that MO stimulation elicited JNK/c-Jun pathway significantly by enhancing phospho-JNK1, phospho-c-Jun expression, and c-Jun activity, which were correlated with an elevated acetylated H3 histone in TG neurons. However, increases in phospho-c-Jun and c-Jun activity were significantly blocked by a JNK inhibitor, SP600125. We also found that altered H3 histone remodeling, assessed by H3 acetylation in triggered TG neurons, was reduced by SP600125. The study suggests that the activated JNK signaling in regulation of histone remodeling may contribute to neuro-epigentic changes in peripheral sensory neurons following environmental neurotoxic exposure.

Gangliogliomas are mixed tumors consisting of both glial elements and differentiated neurons. Although any part of the central nervous system can be affected, little is known about intraventricular gangliogliomas. A patient with a ganglioglioma is presented in the previously unreported location of the anterior third ventricle at the foramen of Monro, mimicking a colloid cyst. We review all other reported cases of intraventricular ganglioglioma (n=6) to characterize this entity. Intraventricular gangliogliomas typically affect younger patients with female predominance (male:female, 2:5; median age 25 years). Symptoms occur secondary to obstruction of physiological cerebrospinal fluid circulation. Complete surgical resection with re-establishment of cerebrospinal fluid drainage is the goal of treatment.

Current evidence suggests an analgesic role for the spinal cord action of general anesthetics; however, the cellular population and intracellular mechanisms underlying anti-visceral pain by general anesthetics still remain unclear. It is known that visceral nociceptive signals are transmited via post-synaptic dorsal column (PSDC) and spinothalamic tract (STT) neuronal pathways and that the PSDC pathway plays a major role in visceral nociception. Animal studies report that persistent changes including nociception-associated molecular expression (e.g. neurokinin-1 (NK-1) receptors) and activation of signal transduction cascades (such as the protein kinase A [PKA]-c-AMP-responsive element binding [CREB] cascade)-in spinal PSDC neurons are observed following visceral pain stimulation. The clinical practice of interruption of the spinal PSDC pathway in patients with cancer pain further supports a role of this group of neurons in the development and maintenance of visceral pain. We propose the hypothesis that general anesthetics might affect critical molecular targets such as NK-1 and glutamate receptors, as well as intracellular signaling by CaM kinase II, protein kinase C (PKC), PKA, and MAP kinase cascades in PSDC neurons, which contribute to the neurotransmission of visceral pain signaling. This would help elucidate the mechanism of antivisceral nociception by general anesthetics at the cellular and molecular levels and aid in development of novel therapeutic strategies to improve clinical management of visceral pain.

An understanding of normal cerebral autoregulation and its response to pathological derangements is helpful in the diagnosis, monitoring, management, and prognosis of severe traumatic brain injury (TBI). Pressure autoregulation is the most common approach in testing the effects of mean arterial blood pressure on cerebral blood flow. A gold standard for measuring cerebral pressure autoregulation is not available, and the literature shows considerable disparity in methods. This fact is not surprising given that cerebral autoregulation is more a concept than a physically measurable entity. Alterations in cerebral autoregulation can vary from patient to patient and over time and are critical during the first 4-5 days after injury. An assessment of cerebral autoregulation as part of bedside neuromonitoring in the neurointensive care unit can allow the individualized treatment of secondary injury in a patient with severe TBI. The assessment of cerebral autoregulation is best achieved with dynamic autoregulation methods. Hyperventilation, hyperoxia, nitric oxide and its derivates, and erythropoietin are some of the therapies that can be helpful in managing cerebral autoregulation. In this review the authors summarize the most important points related to cerebral pressure autoregulation in TBI as applied in clinical practice, based on the literature as well as their own experience.

The incidence of cerebral phaeohyphomycosis, an infection caused by a dark-pigmented fungus, is increasing. The infection may mimic a high-grade glioma clinically and radiographically. Magnetic resonance spectroscopy may be helpful in differentiating the two. We report two cases to increase the awareness of cerebral phaeohyphomycosis in the clinical neurosciences. Early biopsy establishing the diagnosis, followed by aggressive combined surgical and medical management is necessary for a good outcome.

Visceral noxious stimulation induces central neuronal plasticity changes and suggests that the c-AMP-dependent protein kinase (PKA) signal transduction cascade contributes to long-term changes in nociceptive processing at the spinal cord level. Our previous studies reported the clinical neurosurgical interruption of post synaptic dorsal column neuron (PSDC) pathway by performing midline myelotomy effectively alleviating the intractable visceral pain in patients with severe pain. However, the intracellular cascade in PSDC neurons mediated by PKA nociceptive neurotransmission was not known. In this study, by using multiple experimental approaches, we investigated the role of PKA in nociceptive signaling in the spinal cord and PSDC neurons in a visceral pain model in rats with the intracolonic injection of mustard oil. We found that mustard oil injection elicited visceral pain that significantly changed exploratory behavior activity in rats in terms of decreased numbers of entries, traveled distance, active and rearing time, rearing activity and increased resting time when compared to that of rats receiving mineral oil injection. However, the intrathecal infusion of PKA inhibitor, H89 partially reversed the visceral pain-induced effects. Results from Western blot studies showed that mustard oil injection significantly induced the expression of PKA protein in the lumbosacral spinal cord. Immunofluorescent staining in pre-labeled PSDC neurons showed that mustard oil injection greatly induces the neuronal profile numbers. We also found that the intrathecal infusion of a PKA inhibitor, H89 significantly blocked the visceral pain-induced phosphorylation of c-AMP-responsive element binding (CREB) protein in spinal cord in rats. The results of our study suggest that the PKA signal transduction cascade may contribute to visceral nociceptive changes in spinal PSDC pathways.

Background: NF-1 is one of the most common autosomal-dominantly inherited genetic disorders with an incidence of approximately 1:3500. We report a case and review the literature to characterize spontaneous spinal AVF that occur in neurofibromatosis (NF-1)., Case Report: A 51-year-old woman presented with NF-1 and progressive radiculomyelopathy. Angiography revealed an AVF terminating in a giant intraspinal epidural varix extending paraspinally through the C3/4 neural foramen. Trapping of the AVF attempted 18 years earlier prevented endovascular access for embolization, and vigorous bleeding made direct surgical resection impossible. Therefore, as palliation, arterial feeding collaterals were occluded, and surgically exposed tortuous veins were packed with coils. Laminectomies and partial resection of the epidural varix resulted in subtotal occlusion with clinical improvement., Conclusion: The spinal AVF associated with NF-1 appears to show dominant venous drainage to the intraspinal extradural and paraspinal venous plexus without evidence of intradural drainage. The vertebral artery is typically the origin of the fistula. A giant venous varix and numerous collateral feeders to the vertebral artery may give an AVM-like appearance. Clinically, the fistulae produce a syndromic triad including symptoms of NF-1, progressive radiculomyelopathy, and a bruit. Treatment is direct attack on the fistula by either surgery or embolization. If, however, a direct approach cannot be chosen, occlusion of feeding vessels combined with laminectomies can result in long-term symptomatic improvement.

A menu-driven, problem-focused neurological assessment system was constructed and implemented after concerns at a six-hospital teaching center about the quality of nursing assessments for patients with neurological diagnoses were validated. This system enables the physician to guide the nurse's assessment by ordering specific neurological tests for each patient. Extensive staff training took place to develop competence with this system. This new system has resulted in positive changes for this facility. Nurses acknowledge greater comfort with performing neurological assessment; documentation of assessment has improved; and the assessments are becoming more individualized for each patient. This system resulted in a higher quality of neurological care for patients.

To assess the feasibility of passive marker computer-aided surgery in a single institution, we performed 22 procedures in 21 patients with disorders including sinonasal tumors (n = 9), fungal sinusitis (n = 4), recurrent polyps (n = 3), chronic sinusitis (n = 3), and cerebrospinal fluid rhinorrhea (n = 2). Passive marker computer-aided surgery was successful in 19 of the 21 patients. The accuracy was on the order of 1.35 mm. Probe conversion, rotation, and cordlessness were helpful in all 19 cases. The system helped with landmarks (n = 14), margins (n = 7), skull base (n = 6), orbit (n = 5), and approach (n = 4). Computer-aided surgery accurately confirmed the location of an instrument and demonstrated tumor-normal tissue interfaces. It aided the surgeon in procedures on the sinonasal area and cranial base. The potential advantages of a passive marker system as compared with other available technologies center around the ability to convert and/or rotate virtually any instrument to a cordless imaging probe on demand during the operation.

Object: The purpose of this study was twofold. First the authors evaluated preoperative embolization alone to reduce estimated blood loss (EBL) when resecting hypervascular lesions of the thoracolumbar spine. Second, they compared this experience with intraoperative cryotherapy alone or in conjunction with embolization to minimize further EBL., Methods: Twelve patients underwent 13 surgeries for hypervascular spinal tumors. In 10 cases the surgeries were augmented by preoperative embolization alone. In one patient, two different surgeries involved intraoperative cryocoagulation, and in one patient surgery involved a combination of preoperative embolization and intraoperative cryocoagulation for tumor resection. When cryocoagulation was used, its extent was controlled using intraoperative ultrasonography or by establishing physical separation of the spinal cord from the tumor. In the 10 cases in which embolization alone was conducted, intraoperative EBL in excess of 3 L occurred in five. Mean EBL was of 2.8 L per patient. In one patient, who underwent only embolization, excessive bleeding (> 8 L) required that the surgery be terminated and resulted in suboptimum tumor resection. In another three cases, intraoperative cryocoagulation was used alone (in two patients) or in combination with preoperative embolization (in one patient). In all procedures involving cryocoagulation of the lesion, adequate hemostasis was achieved with a mean EBL of only 500 ml per patient. No new neurological deficits were attributable to the use of cryocoagulation., Conclusions: Preoperative embolization alone may not always be satisfactory in reducing EBL in resection of hypervascular tumors of the thoracolumbar spine. Although experience with cryocoagulation is limited, its use, in conjunction with embolization or alone, suggests it may be helpful in limiting EBL beyond what can be achieved with embolization alone. Cryocoagulation may also assist resection by preventing spillage of tumor contents, facilitating more radical excision, and enabling spinal reconstruction. The extent of cryocoagulation could be adequately controlled using ultrasonography or by establishing physical separation between the tumor and spinal cord. Additionally, somatosensory evoked potential monitoring may provide early warning of spinal cord cooling.

The effectiveness of mannitol for the treatment of cerebral edema after stroke has long been debated, and the diffusion of mannitol through a disrupted blood-brain barrier has been the focus of many contradictory studies. The authors present a unique case in which chemical shift imaging was used to demonstrate the accumulation of mannitol in an area of stroke underlying a subdural hematoma in a patient with end-stage renal disease being treated with hemodialysis. A metabolite map for the xenobiotic mannitol was created from the data and demonstrated the accumulation of mannitol when hemodialysis was interrupted prematurely. Metabolite maps were also used to show removal of the mannitol with the reestablishment of hemodialysis. It is concluded that mannitol can accumulate in an area of infarction, and that chemical shift imaging can be used to illustrate this process.

During pterional craniotomy, the sphenoid ridge is resected to facilitate the dissection of the arachnoid in the Sylvian fissure. It is a common intra-operative perception that a deep sphenoid ridge often accompanies a shallow fissure. We explored this unique relationship between the sphenoid ridge and the Sylvian fissure. We studied 46 fresh adult cadavers and measured the depth of both the sphenoid ridges and the Sylvian fissure. The deepest portion of the sphenoid ridge was determined and its depth measured by using a narrow ruler with a sliding gauge. The depth of the Sylvian fissure was measured from the middle cerebral artery bifurcation perpendicularly to the surface of the temporal pole where the arachnoid was cut. An inverse relationship exists between the Sylvian fissure and the sphenoid ridge. The depth of the sphenoid ridge averages 7.28 mm +/- 0.3 mm while the depth of the Sylvian fissure averages 9.0 mm +/- 0.4 mm. Approximately 25% of studied population have deep ridges, i.e. greater than 10 mm, and approximately 25% have shallow ridges, i.e. less than 4 mm. The extent to which the sphenoid ridge projects into the Sylvian fissure determines the depth of the Sylvian fissure thus explaining their inverse relationship. Importantly, encountering a shallow sphenoid ridge during surgery most likely will result in the dissection of a deep Sylvian fissure while a deep ridge predicts a shallow fissure.

Two cases of hematogenous, pyogenic, subaxial cervical facet joint infection are reported, and the literature is reviewed. Infection of the cervical facet joint is a rarely diagnosed condition; only one case has been reported in the literature. Lumbar facet joint infections are also rare but more commonly reported. Approximately one fourth of facet joint infections in the lumbar spine are complicated by epidural abscess formation, which can lead to a neurological deficit. Because of the paucity of reports on cervical facet joint infections, the clinical characteristics of this entity are not well known. Both patients presented with an acute onset of unilateral neck pain that radiated into the ipsilateral shoulder. Frank radicular pain was initially absent. Unilateral upper-extremity motor weakness that was attributed to associated epidural abscess or granulation tissue formation was also demonstrated in both patients. Leukocyte count and erythrocyte sedimentation rate were elevated in both cases. Magnetic resonance imaging was necessary to obtain an accurate diagnosis. Staphylococcus aureus was identified as the offending pathogen in both cases. Decompressive surgery and antibiotic therapy were required to cure the condition. One patient recovered completely and the other sustained a permanent motor deficit. Hematogenous cervical facet joint infection is a rare clinical entity that has many characteristics in common with the more-common lumbar homolog. All three reported cases, however, have been complicated by epidural abscess or granulation tissue formation that has led to a neurological deficit. This finding suggests that a facet joint infection in the cervical spine may have a less benign clinical course than that in the lumbar spine.

We studied 35 successive patients who underwent subaxial lateral mass fixation between June 1994 and January 1996. Follow-up ranged from 2 to 3 1/2 years. Postoperative computed tomography scans showed 45 of 146 screws (31%) had suboptimal trajectory, but only 2 screws minimally impinged the foramen transversarium without adverse sequelae. The fusion rate was 89%. Study results show that optimal drilling technique and trajectory (15 degrees-25 degrees rostral in the sagittal plane, 20 degrees-30 degrees lateral in the axial plane) and intraoperative somatosensory evoked potential monitoring are associated with good screw placement and avoidance of complications, and bone grafting is associated with higher fusion rates.

Objective and Importance: Oncocytoma in the central nervous system is extremely unusual. The first reported example of oncocytoma in a melanocytoma of the spinal cord was successfully excised, and its pathological appearance is described., Clinical Presentation: A 71-year-old woman presented with a 25-year history of back pain and myelographic evidence of a lumbar spinal cord mass. After declining surgical treatment for two decades, she elected eventually to have the mass excised. Preoperative magnetic resonance imaging revealed a large intraspinal mass that spanned spinal levels L3 through S1., Technique: The mass was excised en bloc through posterior laminectomies, and histopathological analysis revealed a benign neoplasm composed predominantly of monotonous sheets of plump oncocytes. Electron microscopy confirmed that the cytoplasm of the oncocytes was packed full of mitochondria. Focal areas of the tumor contained spindle cells, with abundant intracytoplasmic granular deposits of brown melanin pigment that contained melanosomes. Positive Fontana-Masson, HMB-45, and S-100 staining confirmed the final diagnosis of melanocytoma, oncocytic variant., Conclusion: The first reported case of oncocytoma arising in spinal melanocytoma is described. After surgical excision, the patient recovered completely and has remained free of symptoms for 4 years.

Object: This study offers clinical support for the concept that neurosurgical interruption of a midline posterior column pathway by performing a punctate midline myelotomy (PMM) provides significant pain relief without causing adverse neurological sequelae in cancer patients with visceral pain refractory to other therapies., Methods: A PMM of the posterior columns was performed in six cancer patients in whom visceral pain had been refractory to other therapies. The cause of the visceral pain was related to residual, progressive, or recurrent local cancer or postirradiation effects. Clinical efficacy of the procedure was examined by comparing patient pain ratings and narcotic usage pre- and post-PMM. Follow-up periods ranged from 3 to 31 months. Examination of the results indicates a significant reduction in pain ratings as well as a significant reduction in daily narcotic use. No adverse neurological effects were observed. One spinal cord has been recovered for postmortem examination., Conclusions: These findings provide corroborating clinical evidence for the existence of a newly recognized midline posterior column pathway that mediates the perception of visceral pelvic and abdominal pain. Preliminary data indicate that significant pain relief can be obtained following PMM with minimal neurological morbidity and suggest that the procedure may provide an alternative treatment modality for cancer-related pain in patients in whom adequate pain control with narcotics cannot be achieved or narcotic side effects cannot be tolerated.

The current study presents preliminary data regarding the development and validation of a rating system designed to classify PD patients into clinical subgroups. Using portions of the Unified Parkinson's Disease Rating Scale, a ratio value was derived, yielding three patient subtypes: a tremor-dominant group (T), an akinetic-rigid group (AR), and a mixed group (MX). Validation of the schema was conducted by grouping PD surgical candidates into specific disease subtypes and evaluating differences in neurotransmitter profiles among disease subtypes and non-PD neurological controls. High pressure liquid chromatography analysis of ventricular cerebrospinal fluid indicated 5-hydroxyindoleacetic acid was significantly lower in the AR and MX groups compared to non-PD controls; whereas, glycine was significantly higher in the AR group compared to the T, MX, and control groups. The results suggest that an operational approach can be utilized to differentiate between PD subtypes with distinct neurochemical profiles.

Object: The results of previous clinical trials have indicated that intraventricular infusion of nerve growth factor (NGF) in patients with Alzheimer's disease is frustrated by the appearance of weight loss and diffuse back pain. The present study tested whether NGF induces sympathetic sprouting in sensory ganglia. Such sprouting has been implicated in previous studies as a possible mechanism of sympathetically maintained pain in neuropathic animals., Methods: Nineteen Long-Evans rats underwent intraventricular infusion of either artificial cerebrospinal fluid (ACSF; seven animals) or NGF (12 animals). After 14 days of infusion, the sensory ganglia of the trigeminal nerve and the C-2, C-8, T-1, L-4, and L-5 dorsal roots were examined for sympathetic sprouting by using tyrosine hydroxylase immunohistochemical analysis., Conclusions: In the animals receiving NGF, 52 of 144 ganglia showed sympathetic fiber sprouting. In the control animals receiving ACSF, only two of 72 ganglia showed minor sympathetic fiber sprouting. A preferential sprouting of sympathetic fibers was demonstrated at lower lumbar ganglia compared with the cervical and thoracic ganglia. The data presented here demonstrate that in the rat intraventricular NGF infusion caused sympathetic sprouting in dorsal root ganglia (p < 0.01). These findings may have importance both for the treatment of Alzheimer's disease and the understanding of neuropathic pain.

Objective: The study aimed to present clinical, radiographic, and operative findings in cases of recurrent facial neuromas and discuss changes in demographics of primary facial neuromas since 1986., Data Sources: MEDLINE search of English language literature since 1966 and bibliographies of collected articles were the data sources., Study Selection: All available reports of recurrent facial neuromas (N = 8) and case reports of primary facial neuromas since 1986 (N = 238) were selected., Data Extraction: Cases of facial neuromas confirmed by histologic and/or clinical and radiographic criteria are included., Data Synthesis: Compilation of reported anatomic and clinical data is included., Conclusions: Improved imaging techniques have documented an increased incidence of primary facial neuromas medial to the geniculate ganglion. Clinical suspicion, histologic confirmation of tumor-free margins, interspecialty cooperation in tumor resection, and routine follow-up imaging with magnetic resonance imaging are suggested to minimize recurrent facial neuromas.

We report on the conservative and surgical management of a patient with blastomycosis of the lumbar spine, causing severe and crippling deformity. The diagnosis was made through biopsy. Curative removal, reconstruction and realignment of the spine were achieved. Imaging modalities were highlighted, with a detailed discussion of the histology and conservative and surgical management. We emphasize the importance of early, aggressive treatment of blastomycosis to prevent deformity and disability, and to enable identification of the best management of a destructive lesion with deformity. This case demonstrates that empirical treatment should not be used in cases of unusual sinus and abscess locations. Specific diagnosis and early treatment are indicated to prevent dreadful complications and spinal deformity resulting from blastomycosis. Aggressive antifungal therapy can cure the disease but does not control complications related to deformity. The latter can only be addressed by surgical reconstruction. We review the literature of surgical treatment, focusing on abscess drainage, bone fusion and posterior instrumentation in the absence of addressing the deformity component.

Intracranial adenoid cystic carcinoma is uncommon. We report two unusual cases of intracranial adenoid cystic carcinoma. The first patient presented with a steroid-responsive optic neuropathy from an orbital mass that simulated orbital pseudotumor, and subsequently developed intracranial involvement, presumably by contiguous perineural spread. The second patient presented with proptosis of the left eye, right facial weakness and numbness, and an intracranial mass, presumably from hematogenous metastatic spread.

Objective: To examine the cognitive sequelae of unilateral posteroventral pallidotomy., Design: Single-group pretest and posttest methodologic assessment with baseline evaluation performed 1 to 2 days prior to surgery and follow-up conducted 3 months after pallidotomy., Setting: Movement disorder clinic at a university medical center., Patients: Fourteen patients (age range, 43-82 years) with Parkinson disease (average disease duration, 7.4 years)., Intervention: Unilateral posteroventral pallidotomy procedures were performed on the right (n=8) and left (n=6) side of the brain., Main Outcome Measures: The protocol consisted of a range of neuropsychological instruments sensitive to subcortical dysfunction, including measures of bi-manual coordination, simple-complex reaction time, visual attention, naming, verbal fluency, learning, recognition memory, and problem solving., Results: No significant deterioration in specific cognitive abilities was observed as a function of the procedure. Patients showed a significant improvement in motor coordination speed for both contralateral and ipsilateral upper extremities., Conclusions: Stereotactic unilateral posteroventral pallidotomy is associated with minimal risk of adverse neuropsychological effects or cognitive decline. Additional research is warranted, with an increased sample size and extended follow-up, to assess any potential lateralized effects of the procedure.

A punctate midline myelotomy performed in a patient effectively eliminated residual, intractable pelvic pain, which remained after resolution of uterine cervical cancer. The authors describe the case history of the patient, in whom pain assessments were made, and a surgical procedure performed. Despite large doses of opiate analgesic medications, the patient experienced constant pressure pain in the right lower pelvis, with excruciating pain on bowel movement. Severe weight loss necessitated better pain control. A minimally invasive surgical procedure, a 5-mm deep puncture using a 16-gauge needle on either side of the median septum in the dorsal column of the spinal cord (T-8), resulted in no new neurological deficits. Narcotic medication was tapered, no pain was reported, and the patient resumed daily household activity. Midline myelotomy has typically been performed with the intention of eliminating the crossing fibers of the spinothalamic tract in the anterior white matter commissure. The punctate midline myelotomy described here was performed with the specific intention of interrupting a newly described visceral pain pathway that ascends to higher brain centers through the midline of the dorsal column. The effectiveness of the pain relief seen in this patient suggests that visceral pain of the pelvis in humans may be transmitted in the midline of the dorsal column, as has been recently reported in studies using rats. The effectiveness of the punctate midline myelotomy performed in this one case of pelvic visceral pain suggests that the surgery may eventually be effective in greatly reducing or replacing opiate narcotic medication for visceral pain management.

Purpose: To present the technique of percutaneous transpedicular biopsy and debridement of discs in diagnosis and management of discitis., Materials and Methods: Fifteen patients underwent disc biopsy through a transpedicular approach with local anesthesia and fluoroscopic guidance. An attempt was made to debride the disc as much as possible. A surgical vacuum drain was deployed through the transpedicular tract when there was persistent drainage., Results: Fifteen patients underwent percutaneous transpedicular disc biopsy and debridement of disc for suspected discitis. Three patients underwent biopsy only and 12 underwent percutaneous discectomy. Six patients had at least one positive culture. Eight patients who underwent discectomy had immediate improvement of pain or neurologic symptoms, obviating emergency surgical debridement of the disc. Four patients did not improve and underwent surgical debridement and fusion., Conclusions: Transpedicular biopsy of the disc is an effective technique for adequate tissue retrieval and diagnosis of discitis. Adequate debridement in selected patients with antibiotic therapy may be definitive. Epidural extension of discitis and massive vertebral destruction precludes percutaneous treatment.

Objective: We assessed the value of intraoperative ultrasonography (IUS) in cervical corpectomy by using postoperative computed tomography (CT) for comparison., Methods: Twenty patients underwent a one-, two-, or three-level cervical corpectomy. The decompression was performed in a stepwise fashion, guided in each case by IUS findings until considered adequate. Each patient underwent postoperative CT to evaluate the accuracy of the IUS in guiding the decompression., Results: In the 20 patients who underwent corpectomy, IUS guided a complete lateral gutter decompression. No evidence of asymmetry and excessive bone removal was identified by IUS at the end of the procedure. IUS was not useful in assessing the adequacy of longitudinal decompression because of the absence of neural landmarks in the sagittal plane. Postoperative CT confirmed adequate decompression in all patients. The width of decompression at the posterior margin of the vertebral body ranged from 18 to 20 mm, with a mean of 19.2 mm., Conclusion: We conclude that IUS is helpful and reliable in performing a properly centered, thorough, lateral decompression in cervical corpectomy. A limited corpectomy can be started under visual guidance and then enlarged after IUS findings until complete decompression of the neural elements has been achieved. This approach avoids the problems of asymmetry, inadequate decompression, and excessive bony removal that could lead to endangerment of the vertebral artery and possible failure of the reconstruction. The accuracy of the IUS was confirmed in this study by postoperative CT.

The authors describe the method and results of treatment of 12 consecutive patients with carotid-cavernous sinus fistulas (CCFs). Treatment was by embolization via a transvenous approach through the superior ophthalmic vein (SOV). The CCFs (two direct and 10 dural) had previously been treated unsuccessfully or, for mechanical reasons, could not be treated by the standard techniques of endoarterial balloon occlusion, particle or glue embolization of feeding vessels from one or both external carotid arteries, or transvenous occlusion of the fistula via the ipsilateral inferior petrosal sinus. All 12 patients were successfully treated either by advancement of a detachable balloon catheter through the ipsilateral SOV into the cavernous sinus with subsequent inflation and detachment of the balloon (11 patients) or by introduction of multiple thrombogenic coils into the fistula via the ipsilateral SOV (one patient). All patients had complete resolution of symptoms and signs after successful occlusion of the CCF. There were no intraoperative complications; however, one patient required postoperative embolization of a residual posteriorly draining fistula via the ipsilateral external carotid artery, and another developed a persistent abducens nerve paresis that eventually required surgical correction. Ten (83.3%) of the 12 patients underwent cerebral angiography 3 to 6 months after surgery, and none showed evidence of a recurrent fistula. Similarly, none of the 12 patients developed recurrent symptoms and signs suggesting recurrence of the fistula during a follow-up period that ranged from 6 months to 10 years (mean 64 months). It is concluded that the transvenous approach to the cavernous sinus through the SOV is a safe and effective treatment of both direct and dural CCFs that are not amenable to transarterial or other transvenous approaches.

Vessel identification during a transcranial Doppler (TCD) ultrasound examination is usually based on well-established inferential criteria without confirmation by imaging. Part of a routine study involves taking measurements from the M1 segment of the middle cerebral artery (MCA) and the A1 segment of the anterior cerebral artery (ACA) at the points of maximum mean linear blood flow velocity (LBFV). The authors tested the hypothesis that insonation is from the midpoints of the M1 and A1 segments during clinical TCD examinations. Conventional hand-held TCD examinations were performed on five volunteers. The points of maximum mean LBFV of the M1 and A1 segments of the MCA and ACA were located. Measurements were also taken from the midpoints of the M1 and A1 segments using a magnetic resonance (MR) imaging-guided stereotactic TCD technique. Values for depths of insonation and maximum mean LBFV obtained with the two techniques were compared. There was no significant difference between the two techniques for the measured values of depth of insonation of either the individual vessels (p > 0.11) or the aggregate (p = 0.46). There was a significant difference between the aggregate maximum mean LBFV measurements (p = 0.0022). The hand-held technique systematically produced higher maximum mean LBFV than the MR-guided stereotactic technique. The authors conclude that when using traditional criteria for TCD examination of the ACA and MCA, the points of insonation approximate the middle of the A1 and M1 segments.

We present five cases of giant serpentine aneurysms (large, partially thrombosed aneurysms containing tortuous vascular channels with a separate entrance and outflow pathway) and review 28 cases reported in the literature. Giant serpentine aneurysms should be considered as a subgroup of giant aneurysms, distinct from saccular and fusiform varieties, given their unique clinical presentation and radiographic features.

The mechanical accuracy of several available stereotactic instruments is extremely high as measured in tests with rigid phantoms. The author's experience with stereotactic-guided resection by craniotomy using both "frameless" and framed methods simultaneously is that neither the image accuracy nor the mechanical accuracy of the instrument is the limiting factor in the usefulness of the guidance. Rather, it appears that the errors encountered in actual use have to do with tissue position changes which occur during the procedure. The accuracy may be better for extrinsic lesions rigidly attached to the skull, but for intrinsic lesions, tissue position changes occur following the release of cerebrospinal fluid, air entry into the subdural spaces, tumor debulking, or cyst drainage. The potential error appears to be worse with hydrocephalus, intraoperative dehydration, collapse of larger cysts, and debulking of large tumors. Even with very small intrinsic tumors in young, not atrophic patients, the error may be 5 mm. The need for intraoperative update of the guidance image is obvious if greater accuracy is required. The advantages of such "imaging-interactive" stereotactic surgery have long been apparent from stereotactic biopsy procedures performed in the CT scanner where errors such as needle deflection or hemorrhage can be appreciated and corrected promptly. With intraoperative scanning it is also possible to monitor the progress of a cyst aspiration and confirm the site of a biopsy to avoid unnecessary sampling in cases where the pathology is inherently equivocal.

Retrograde thrombosis of feeding arteries is a potentially catastrophic complication occasionally reported following resection of arteriovenous malformations (AVM's). No successful therapy for this condition, which causes postoperative stroke, has previously been reported. A case of retrograde thrombosis of the left middle cerebral artery immediately following resection of a parietal AVM is reported in a patient with a retained intra-arterial catheter from preoperative embolization. The administration of urokinase within 4 hours of surgery resulted in dramatic clinical and angiographic improvement without hemorrhagic complications. While urokinase is considered highly experimental in this setting, this case demonstrates that thrombolytic agents should be viewed as therapeutic options worthy of further investigation.

Basal forebrain cholinergic neurons respond to nerve growth factor (NGF), and it has been suggested that the administration of NGF might prevent their degeneration in patients with Alzheimer's disease. One major prerequisite to be fulfilled before the consideration of clinical trials of NGF in patients with Alzheimer's disease is the demonstration that human NGF affects basal forebrain cholinergic neurons in primates. In the present study, we used a recombinant human nerve growth factor (rhNGF), which we previously showed to be active on rat basal forebrain cholinergic neurons, in nonhuman primates with a unilateral transection of the fornix (a well-established model for the induction of retrograde degenerative changes in septal cholinergic neurons). After the lesion, one group of animals received rhNGF and a second group received vehicle solution for 2 weeks. In animals receiving vehicle, the medial septal nucleus ipsilateral to the lesion showed reductions in number (55%) and size of cell bodies immunoreactive for NGF receptor and choline acetyltransferase. In Nissl stains, many cells showed reduced size and basophilia. The rhNGF completely prevented alterations in the number and size of NGF receptor- and choline acetyltransferase-immunoreactive neurons in the medial septal nucleus and reversed atrophy in a subpopulation of large, basophilic medial septal nucleus neurons, as identified by Nissl stains. The effects of rhNGF were identical to those of mouse NGF, which we have previously used in the same primate lesion paradigm. The restoration of the phenotype of injured cholinergic septal neurons by rhNGF in the monkey raises the possibility that this factor may be used to ameliorate acetylcholine-dependent memory impairments that occur in aged nonhuman primates. In concert, results of the present investigation provide critical information for the future use of NGF in patients with neurological disorders that affect NGF-responsive cells in the peripheral and central nervous systems.

Fifteen patients with cerebral involvement by malignant non-Hodgkin's lymphoma were identified, among more than 200 patients who underwent stereotactic biopsy at The Johns Hopkins Hospital. All but one of these cases were diagnosed accurately by the stereotactic biopsy procedure. In 12 of 14 patients, the material was adequate to classify the lymphoma according to the Working Formulation. Because all but one of the lesions were intermediate or high-grade neoplasms, a diagnosis of lymphoma was often possible by conventional light microscopic examination alone. Monotypic light chain expression was demonstrated by immunohistochemical techniques in six patients, and positivity for B-cell markers was observed in an additional case. In one instance, two stereotactic biopsy specimens were interpreted as being suggestive of lymphoma, but necrosis and inflammation prevented a definitive diagnosis. Nine patients had no known risk factors for cerebral lymphoma, and the diagnosis often was unsuspected clinically.

Symptomatic patients with dural carotid-cavernous fistulas often require treatment. Traditional therapies, which often are not completely successful, include manual common carotid artery compression and embolization via transarterial routes. This report describes four symptomatic patients with spontaneous dural carotid-cavernous fistulas who were treated unsuccessfully with transarterial embolotherapy and subsequently treated successfully by having a detachable balloon introduced into the cavernous sinus via the superior ophthalmic vein, which was surgically exposed. The fistulas resolved without complications. Treatment of dural carotid-cavernous fistulas by means of the transvenous approach via the superior ophthalmic vein may be of benefit in selected patients.

NGF, a trophic polypeptide, is necessary for the normal development and survival of certain populations of neurons in the CNS and PNS. In the CNS, cholinergic neurons of the basal forebrain magnocellular complex (BFMC) are prominent targets of NGF. During rat development, NGF increases the activity of ChAT in these neurons. In adult rats with experimental injury of axons in the fimbria-fornix, NGF prevents degenerative changes in axotomized cholinergic BFMC neurons in the medial septal nucleus (MSN). Because the amino acid sequences of NGF and its receptor (NGF-R) are highly conserved across species, we hypothesized that mouse NGF would also prevent degeneration of cholinergic BFMC neurons in nonhuman primates. Therefore, the present study was designed to test whether fimbria-fornix lesions result in retrograde degenerative changes in basal forebrain cholinergic neurons in macaques, whether these changes are prevented by mouse NGF, and whether the protective effect of NGF is selective for cholinergic neurons of the basal forebrain. Following unilateral complete transection of the fornix, animals were allowed to survive for 2 weeks, during which time half of the subjects received intraventricular NGF in vehicle and the other half received vehicle alone. In animals receiving vehicle alone, there was a 55% reduction in the number of ChAT-immunoreactive cell bodies within the MSN ipsilateral to the lesion; loss of immunoreactive somata was more severe in caudal planes of the MSN. Remaining immunoreactive neurons appeared smaller than those in control, unoperated animals. In Nissl stains, there was no apparent loss of basophilic profiles in the MSN, but cells showed reduced size and intensity of basophilia. Treatment with NGF almost completely prevented reductions in the number and size of cholinergic neurons and had a significant general effect in preventing atrophy in basophilic magnocellular neurons of the MSN, though some basophilic neurons in the MSN did not appear to respond to NGF. Adjacent 7-microns-thick sections stained with ChAT and NGF-R immunocytochemistry revealed that these markers are strictly colocalized in individual neurons in the MSN in controls and in both groups of experimental animals. Thus, mouse NGF profoundly influences the process of axotomy-induced retrograde degeneration in cholinergic BFMC neurons in primates. The in vivo effectiveness of mouse NGF on primate BFMC neurons suggests that mouse or human recombinant NGF may be useful in ameliorating the ACh-dependent, age-associated memory impairments that occur in nonhuman primates.(ABSTRACT TRUNCATED AT 400 WORDS)

Combined intrathecal metrizamide and arterial injection of contrast medium during dynamic computed tomography scanning was used to define the morphology and topographic aspects of a thoracic arteriovenous malformation. The information obtained from this new technique was decisive in establishing the operability of the lesion.

The anatomy of the spinal subarachnoid space is reviewed with special reference to the work of Key and Retzius, the authors' own cadaver dissections, and experience from operative cases. It appears that despite some variations in the spinal arachnoid anatomy, there are many consistent features that can serve to guide the operating neurosurgeon.