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External ventricular drain (EVD) infections are a significant cause of morbidity among neurosurgical patients and have been correlated with increased length of hospital stay and longer requirements for intensive care. To date, no studies have examined the financial impact of EVD infections.Patients who underwent EVD placement between December 2010 and January 2016 were included in the study. Clinical records were retrospectively reviewed and health care cost data were obtained from the hospital's finance department. Clinical information included patient demographics, details from the hospital course, and outcomes. Total costs, direct/indirect, and fixed/variable costs were analyzed for every patient.Over the 5-year study period, 246 EVDs were placed in 243 patients with an overall infection rate of 9.9% (N = 24). The median EVD duration for infected versus noninfected patients was 19 and 9 days, respectively (P 0.0001). Median length of intensive care unit stay also was increased for patients with EVD infection (30 days vs. 13 days, P0.0001). Total health care costs were significantly greater for infected patients (US$ 168,692 vs. US$ 83,919, P0.0001). This trend was comparable for all other cost subtypes, including fixed-direct costs, fixed-indirect costs, variable direct costs, and variable-indirect costs.EVD infection has a substantial effect on clinical morbidity and healthcare costs. These results demonstrate the imperative need to improve EVD infection prevention, particularly in the setting of a value-based health care system.

BACKGROUND Ventriculostomy-related infection (VRI) is a feared complication of external ventricular drain (EVD) placement. Although many contributing factors to VRI have been examined, little is known whether there is an association between ventriculostomy-related catheter tract hemorrhage (VCTH) and VRI. OBJECTIVE To evaluate risk factors for VRI and assess possible correlations with VCTH. METHODS We performed a retrospective analysis of patients with EVD placement in a neurocritical care unit between 2011 and 2015. VRI was defined as clinical signs of infection with a positive cerebrospinal fluid gram stain and isolation of cerebrospinal fluid culture. VCTH was diagnosed by computed tomography immediately after EVD insertion. RESULTS A total of 247 patients with EVD were identified during the 5-yr study period. An association between VCTH and gram-negative VRI was identified (P = .02). Ten percent (25 of 247 patients) developed a VRI, and 7% (18 of 247 patients) had a VCTH. Of the 25 patients with VRI, 20% (n = 5) had a VCTH, compared to 6% (n = 13) of 222 patients who had an EVD placed but did not develop VRI. There were no significant differences in demographic and clinical factors except for multiple EVD insertions (P

The normal organization and plasticity of the cutaneous core of the thalamic principal somatosensory nucleus (ventral caudal, Vc) have been studied by single-neuron recordings and microstimulation in patients undergoing awake stereotactic operations for essential tremor (ET) without apparent somatic sensory abnormality and in patients with dystonia or chronic pain secondary to major nervous system injury. In patients with ET, most Vc neurons responded to one of the four stimuli, each of which optimally activates one mechanoreceptor type. Sensations evoked by microstimulation were similar to those evoked by the optimal stimulus only among rapidly adapting neurons. In patients with ET, Vc was highly segmented somatotopically, and vibration, movement, pressure, and sharp sensations were usually evoked by microstimulation at separate sites in Vc. In patients with conditions including spinal cord transection, amputation, or dystonia, RFs were mismatched with projected fields more commonly than in patients with ET. The representation of the border of the anesthetic area (e.g., stump) or of the dystonic limb was much larger than that of the same part of the body in patients with ET. This review describes the organization and reorganization of human Vc neuronal activity in nervous system injury and dystonia and then proposes basic mechanisms.

It is hard to imagine a more challenging arena for communication research than that presented by new media and their impact on our society. We have witnessed the fastest evolution in communication technology in human history and, along with it, the evolution of communication conceptions and theories used to assess its impact. More than a decade has passed since Chaffee and Metzger first published their intriguing article “The End of Mass Communication?” and suggested that the new media will change the notions of mass communication and, as a result, the theories used in communication research. Today, we know more about new media and its effect on communication, society, and communication theories. The present article, therefore, sets out to reassess Chaffee and Metzger's claim by describing the development of several core theories of communication research, namely the agenda-setting theory and the notions of media audiences and the Digital Divide, in light of the new media. Our review shows that the role p...

Amniotic band sequence (ABS) is a condition in which rupture of the amniotic sac leads to the development of a broad spectrum of fetal anomalies. A newborn male presented at term with multiple craniofacial and skeletal anomalies, including attachment of the placenta to the head, a paramedian facial cleft, and multiple skeletal anomalies. The patient has undergone several operations to date. The initial operation was performed to remove the attached placenta off the underlying dura, which was with a collagen matrix bound to a silicone membrane. The patient subsequently underwent split-thickness skin grafting with complete survival of the graft.

Although the response of human cutaneous mechanoreceptors to controlled stimuli is well studied, it is not clear how these peripheral signals may be reflected in neuronal activity of the human CNS. We now test the hypothesis that individual neurons in the human thalamic principal somatic sensory nucleus [ventral caudal (Vc)] respond selectively to the optimal stimulus for one of the four mechanoreceptors. The optimal stimuli for particular mechanoreceptors were defined as follows: Pacinian corpuscles (PC), vibration at 128 Hz; rapidly adapting (RA), vibration at 32 or 64 Hz; slowly adapting type 1 (SA1), edge; slowly adapting type 2 (SA2), skin stretch. Nineteen neurons had a significant response to at least one optimal stimulus, and 17 had a significantly greater response to one stimulus than to the other three, including 7 PC-related, 7 RA-like, 3 SA1-like, and 2 SA2-like neurons. One of each of the SA1- and SA2-like thalamic neurons responded to vibration with firing rates that were lower than those to edge or stretch but not significantly. Except in the case of PC-related neurons, the receptive field (RF) sizes were larger for these thalamic neurons than for the corresponding mechanoreceptor. Von Frey thresholds were higher than those for the corresponding human RA and SA1 mechanoreceptors. These results suggest that there is a convergence of pathways transmitting input from multiple mechanoreceptors of one type on single thalamic neurons via the dorsal columns. They are also consistent with the presence of primate thalamic elements of modality and somatotopic isorepresentation.

Our previous study has shown that directed attention to a painful stimulus is associated with increased synchrony between electrocorticographic (ECoG) oscillations in pain-related cortical structures. We now test the hypothesis that the synchrony or functional connectivity of this pain network differs between events during which pain is or is not perceived (pain or non-pain events) in response to a noxious cutaneous laser stimulus. ECoG recordings were made through subdural electrodes implanted in a patient for the treatment of epilepsy. The patient was instructed that the stimulus could be painful or non-painful on any given presentation. Synchrony between ECoG signals at different sites was measured during the pre-stimulus interval, and the difference in the number of sites with significant pre-stimulus synchrony was compared between pain and non-pain events. Pre-stimulus synchrony was more common during pain versus non-pain events among electrodes overall, and in the subset of electrodes at which laser-evoked potentials (LEPs) were recorded. This difference between pain and non-pain events was also significant for the subset of electrodes over medial cortex, including anterior cingulate cortex (ACC), but not for subsets of electrodes over the superior and inferior convexity, including primary somatosensory (S1) and parasylvian cortex (PS), respectively. These results suggest that dynamic changes in the functional connectivity between ACC and other cortical regions enable the perception of pain in response to noxious stimuli.

✓ Synovial chondromatosis is an uncommon disorder characterized by the formation of multiple cartilaginous nodules within the synovium, most commonly affecting large joints. Its involvement with the spine is rare; only six cases have been reported. The authors describe two patients with synovial chondromatosis involving the cervical spine. In the first case, synovial chondromatosis arose from the left C1–2 facet joint. This patient underwent a two-stage procedure including a posterior approach for tumor resection and occipitocervical fusion as well as a transmandibular circumglossal approach to the anterior craniocervical junction to complete the tumor removal. Interestingly, on histopathological examination, scattered foci of low-grade chondrosarcoma were intermixed within the synovial chondromatosis. To the authors' knowledge, this is the first report of secondary low-grade chondrosarcoma arising in vertebral synovial chondromatosis. In the second case, synovial chondromatosis involved the left C4–5 facet joint. Tumor resection and cervical fusion were performed via a posterior approach. In this report, the authors describe the clinical presentation, radiographic findings, operative details, histopathological features, and clinicoradiological follow-up data obtained in these two patients and review the literature pertaining to this rare entity.

Intensity encoding of painful stimuli in many brain regions has been suggested by imaging studies which cannot measure electrical activity of the brain directly. We have now examined the effect of laser stimulus intensity (three energy levels) on laser evoked potentials (LEPs) recorded directly from the human primary somatosensory (SI), parasylvian, and medial frontal cortical surfaces through subdural electrodes implanted for surgical treatment of medically intractable epilepsy. LEP N2* (early exogenous/stimulus-related potential) and LEP P2** (later endogenous potential) amplitudes were significantly related to the laser energy levels in all regions, although differences between regions were not significant. Both LEP peaks were also significantly correlated with the pain intensity evoked by the laser stimulus, excepting N2* over the parasylvian region. Peak latencies of both LEP peaks were independent of laser energy levels. N2* and P2** amplitudes of the maxima in all regions showed significant positive linear correlations with laser energy, excepting N2* over the parasylvian region. The lack of correlation of parasylvian cortical N2* with laser energy and pain intensity may be due to the unique anatomy of this region, or the small sample, rather than the lack of activation by the laser. Differences in thresholds of the energy correlation with amplitudes were not significant between regions. These results suggest that both exogenous in endogenous potentials evoked by painful stimuli, and recorded over SI, parasylvian, and medial frontal cortex of awake humans, encode the intensity of painful stimuli and correlate with the pain evoked by painful stimuli.

Negative and positive laser evoked potential (LEP) peaks (N2*, P2**) were simultaneously recorded from the primary somatosensory (SI), parasylvian, and medial frontal (MF: anterior cingulate and supplementary motor area) cortical surfaces through subdural electrodes implanted for the surgical treatment of intractable epilepsy. Distribution of the LEP N2*and P2**peaks was estimated to be in cortical areas (SI, parasylvian, and MF) identified by anatomic criteria, by their response to innocuous vibratory stimulation of a finger (v-SEP), and to electrical stimulation of the median nerve (e-SEP). The maximum of the LEP N2*peak was located on the CS, medial (dorsal) to the finger motor area, as determined by cortical stimulation, and to the finger somatosensory area, as determined from the e-SEP and v-SEP. This finding suggests that the generator source of the LEP N2*peak in SI was different from that of e-SEP or v-SEP in Brodmann's areas 3b or 1. In parasylvian and MF, polarity reversal was often observed, indicating tangential current sources in these regions. In contrast to e-SEP and v-SEP, the LEP N2*latency over SI was not shorter than that over the parasylvian region. The amplitude of N2*was larger over SI than over MF and the latencies of the LEP peaks in those 2 regions were different. These findings provide evidence for a significant LEP generator in the postcentral gyrus, perhaps SI cortex, that is situated outside the tactile homunculus in SI and that receives its input arising from nociceptors simultaneously with parasylvian and MF cortex.

Background Communication via e-mail has become widespread. Nearly every practicing neurosurgeon is confronted with numerous unsolicited e-mail requests for medical advice, guidance, or information. Neurosurgeons need to be aware of the clinical, financial, legal, and ethical implications of providing medical consultation via e-mail. Methods A literature review of the penetration of e-mail consultation in medical practice was performed. The data on the potential for reimbursement for provision of these services is presented. Precedents for legal liability are discussed, and issues of compliance with HIPAA regulations are reviewed. Results Communication between patients and physicians via e-mail is increasing in prevalence, and a substantial number of physicians are providing medical information via e-mail consultation. Billing for online consultation has been approved by the American Medical Association, and several medical insurance carriers are evaluating the economic consequences of reimbursement for e-mail consultation. E-mail consultation raises potential medico-legal concerns, including establishment of the physician-patient relationship, malpractice liability, and HIPAA compliance. Conclusions The increasing prevalence of e-mail consultation raises new concerns for neurosurgeons. Some of these concerns have yet to be addressed by regulatory commissions or in the courts. If used appropriately, e-mail communication can facilitate physician-patient interactions, improve access to care, save time for each interaction, and possibly reduce costs of care.

✓ The authors present the case of a 49-year-old woman with disabling bilateral upper-extremity cerebellar tremor that resolved unexpectedly after placement of an intrathecal baclofen pump for lower-extremity spasticity. The tremor amplitude decreased nearly linearly with increasing intrathecal baclofen dosage, and disappeared completely at a dose of 250 µg/day. In this report the authors demonstrate the role of the γ-aminobutyric acidergic system in the pathogenesis of cerebellar tremor, and these findings may lead to a new treatment modality for patients disabled by this manifestation of their disease.

Atlas of emergency neurosurgery , Atlas of emergency neurosurgery , کتابخانه الکترونیک و دیجیتال - آذرسا

A 51-year-old man with several months of headache and progressive visual decline was found to have bilateral optic disc pallor with significant impairment of visual acuity. Despite a thorough ophthalmologic evaluation, the cause of visual loss could not be elucidated. MRI of the brain revealed a lesion in the left anterior Sylvian fissure as well as disseminated foci of subarachnoid fat consistent with a diagnosis of a ruptured dermoid cyst. The decision for open surgical resection was chosen to minimize the risk of cyst re-rupture and further visual or neurologic decline. The diagnosis of dermoid cyst was confirmed at the time of surgery. Vasospasm-induced ischemia of the optic nerves, optic chiasm or bilateral optic tracts secondary to the inflammatory reaction following cyst rupture is the most likely mechanism of visual loss in this patient. To the authors' knowledge, this report represents the first reported case of visual loss secondary to rupture of an intracranial dermoid cyst not related to mass effect of the tumor on the optic apparatus, visual pathways or visual cortex.

Functional imaging studies show that motor imagery activates multiple structures in the human forebrain. We now show that phantom movements in an amputee and imagined movements in intact individuals elicit responses from neurons in several human thalamic nuclei. These include the somatic sensory nucleus receiving input from the periphery (ventral caudal), and the motor nuclei receiving input from the cerebellum [ventral intermediate (Vim)] and the basal ganglia [ventral oral posterior (Vop)]. Seven neurons in the amputee showed phantom movement-related activity (three Vim, two Vop, and two ventral caudal). In addition, seven neurons in a group of three controls showed motor imagery-related activity (four Vim and three Vop). These studies were performed during single neuron recording sessions in patients undergoing therapeutic treatment of phantom pain, tremor, and chronic pain conditions by thalamic stimulation. The activity of neurons in these sensory and motor nuclei, respectively, may encode the expected sensory consequences and the dynamics of planned movements.

Arachnoiditis ossificans is an uncommon clinical entity in which arachnoid ossification leads to clinical symptomatology. In this case report, we describe the case of a myelopathic patient with arachnoid ossifications, an arachnoid cyst, and syringomyelia coexisting with a herniated thoracic disc at the same levels.An 81-year-old woman presented with rapidly progressive leg weakness, dysesthetic pains, and urinary incontinence.The patient underwent thoracic laminectomy with costotransversectomy for resection of ossified arachnoid and re-establishment of cerebrospinal fluid pathways.Altered cerebrospinal fluid dynamics secondary to the obstruction in subarachnoid flow may predispose to the formation of an arachnoid cyst, and the cyst itself may be the proximate cause of the myelopathy.

Imaging studies indicate that experimental pain is processed in multiple cortical areas which are often characterized as a network. However, the functional connectivity within the network and the other properties of the network is poorly understood. Substantial evidence demonstrates that synchronous oscillations between two cortical areas may indicate functional connectivity between those areas. We test the hypothesis that cortical areas with pain-related activity are functionally connected during attention to a painful stimulus. We stimulated with a painful, cutaneous, laser stimulus and recorded the response directly from the cortical surface (electrocorticography – ECoG) over primary somatosensory (SI), parasylvian (PS), and medial frontal (MF) cortex through subdural electrodes implanted for treatment of epilepsy. The results demonstrate synchrony of ECoGs between cortical structures receiving input from nociceptors, as indicated by the occurrence of laser-evoked potentials (LEPs) and/or event-related desynchronization (ERD). Prior to the stimulus, directed attention to the painful stimulus consistently increased the degree of synchrony between SI and PS regions, as the subject anticipated the stimulus. After the laser stimulus, directed attention to the painful stimulus consistently increased the degree of synchrony between SI and MF cortex, as the subject responded by counting the stimulus. Therefore, attention to painful stimuli always enhanced synchrony between cortical pain-related structures. The pattern of this synchrony changed as the patient switched tasks from anticipation of the stimulus to counting the stimulus. These results are the first compelling evidence of pain networks characterized by rapidly switching, task-specific functional connectivity.

Objective To test the hypothesis that attention to painful cutaneous laser stimuli enhances event-related desynchronization (ERD) in cortical regions receiving nociceptive input. Methods We used wavelet time–frequency analysis and bandpass filtering to measure ERD quantitatively in subdural electrocorticographic recordings while subjects either attended to, or were distracted from, a painful cutaneous laser stimulus. Results ERD were observed over primary somatosensory and parasylvian (PS) cortices in all 4 subjects, and over medial frontal cortex in 1 subject. Laser-evoked potentials were also observed in all 3 regions. In all subjects, ERD was more widespread and intense, particularly over PS, during attention to laser stimuli (counting stimuli) than during distraction from the stimuli (reading for comprehension). Conclusions These findings suggest that pain-associated ERD is modulated by attention, particularly over PS. Significance This study suggests that thalamocortical circuits are involved in attentional modulation of pain because of the proposed role of these circuits in the mechanisms of ERD.

Painful cutaneous laser stimuli evoked potentials (LEPs) were recorded over the primary somatosensory (SI), parasylvian, and medial frontal (MF) cortex areas in a patient with subdural electrode grids located over these areas for surgical treatment of epilepsy. The amplitudes of the negative (N2*) and positive (P2**) LEP peaks over SI, parasylvian, and MF cortex were enhanced by attention to (counting stimuli), in comparison with distraction from the stimulus (reading for comprehension). Late positive deflections following the P2** peak (late potential—LP) were recorded over MF and from the lateral premotor regions during attention but not during distraction. These findings suggest that attention gates both early (N2*) and late (P2**) pain-related input to SI, parasylvian, and MF cortical regions while the later components (LP) are specifically related to attention.

Publisher Summary This chapter discusses the anatomy and physiology of the human thalamic and cortical structures that may mediate the sensation of pain. The human thalamic and cortical structures are the sensory discriminative and the motivational-affective aspect of pain. Studies in humans have demonstrated the involvement of both the lateral and medial thalamus in pain processing. In the lateral thalamus, cells responsive to painful stimuli are located in the core area and in the postero-inferior area. Stimulation in the postero-inferior area or at the posterior aspect of the core can evoke pain or visceral pain suggesting the involvement of this area in the mechanism of somatic and visceral pain. Abnormalities in the lateral thalamus in patients with chronic pain point to the involvement of this area in chronic pain in humans. A reorganization of modalities occurs in patients with chronic pain so that the number of sites where thermal sensations are normally evoked by thalamic stimulation is decreased by an amount equal to the increase in the number of sites where pain is evoked.

The authors present the case of a 49-year-old woman with disabling bilateral upper-extremity cerebellar tremor that resolved unexpectedly after placement of an intrathecal baclofen pump for lower-extremity spasticity. The tremor amplitude decreased nearly linearly with increasing intrathecal baclofen dosage, and disappeared completely at a dose of 250 microg/day. In this report the authors demonstrate the role of the gamma-aminobutyric acidergic system in the pathogenesis of cerebellar tremor, and these findings may lead to a new treatment modality for patients disabled by this manifestation of their disease.

Talc pleurodesis is a technique used in the treatment of patients with persistent pleural effusions or pneumothorax not amenable to other treatment. These are commonly seen in patients with malignant thoracic neoplasms. Radiographic abnormalities resulting from prior talc pleurodesis could be confused with progression of the underlying neoplastic process. Positron emission tomography with F-18 fluorodeoxyglucose (FDG-PET) might be unable to distinguish between malignant and benign inflammatory processes. This report demonstrates the use of combined positron emission tomography/computed tomography (PET/CT) in a patient with a history of both malignant neoplasm and a prior talc pleurodesis. Fusion of PET and CT studies could add information that CT and PET alone cannot. This could alter the diagnostic and therapeutic course for patients with a history of both thoracic neoplasm and talc pleurodesis.

OBJECTIVE This study sought to evaluate the ability of blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) to successfully identify functional cortical areas in patients with primary brain tumors, to evaluate the use of the fMRI results in presurgical planning, and to assess the functional outcome of the patients with respect to the functional maps obtained with fMRI. METHODS The study included 25 consecutive preoperative fMRI sessions in patients with primary brain tumors in or near sensorimotor and/or language cortices. All fMRI paradigms were analyzed and rated according to the degree of success. Several distances between tumor and functional cortex as delineated with BOLD fMRI were measured to assess the topographic relationship between these two structures. Pre- and postoperative neurological statuses were obtained from the patients' journals. RESULTS Acquisition of BOLD fMRI images was successful in 80% of the cases. The primary cause of unsuccessful fMRI was echo-planar imaging signal voids that were the result of previous craniotomy; the secondary cause was excessive motion. The neurosurgeons used the fMRI results for preoperative planning in 75% of the cases in which fMRI was successful. The risk of postoperative loss of function tested with fMRI was significantly lower when the distance between tumor periphery and BOLD activity was 10 mm or more. CONCLUSION The majority of patients with primary brain tumors were capable of satisfactorily performing the fMRI paradigms, and the information obtained was used in the preoperative planning. A distance of 10 mm or more between the functional cortex, as delineated with fMRI, and the tumor significantly reduced the risk of postoperative loss of function.

Hypoxia chemotransduction within the carotid body is generally believed to be mediated by the glomus cells. Neurotransmitters (primarily dopamine) are stored within glomus cells in dense-cored vesicles, and catecholamine secretion is enhanced by hypoxia. Glomus cells are apposed to afferent terminals of the sinus nerve, and hypoxia-induced release of catecholamines leads to increased sinus nerve spiking activity. Two theories have evolved in an attempt to elucidate the cellular mechanisms involved in hypoxia-induced glomus cell secretion. In one model, hypoxia inhibits an oxygen-sensitive K+ channel, leading to depolarization, activation of voltage-dependent Ca2+ currents, and enhanced secretion of catecholamine due to increased intracellular calcium (Gonzalez et al, 1994). In support of this model, several investigators have observed an inhibition of glomus cell K+ current by hypoxia during patch-clamp recording of isolated glomus cells, and this inhibition appears to be correlated with an increase in [Ca2+]i and enhanced secretion (Montoro et al, 1996). In contrast, others have observed an increase in [Ca2+]i during hypoxia in the absence of extracellular calcium, implicating a second model, in which hypoxia causes release of calcium from intracellular stores, leading to enhanced secretion (Biscoe et al, 1989a; Biscoe & Duchen, 1990). In this second model, depolarization and calcium influx are not important events in the stimulus cascade. This is supported further by observations that membrane potential may actually hyperpolarize, rather than depolarize, during stimulation (Biscoe & Purves, 1989b).

Chronic pain is an immense, unsolved, clinical problem. Current approaches to this condition are limited by uncertainty about mechanisms of acute and chronic pain in humans. Although much progress has been made toward understanding peripheral neural mechanisms of human nociception, we have a poor understanding of CNS pain mechanisms. Here, we review the anatomy and physiology of the ascending spinal pathways and supraspinal centers with pain-related activity. This review focuses on the primate nervous systems because there are significant differences between pain transmission in primates and other species such as cats and rats.