Search Results

You are looking at 1 - 10 of 726 items for :

  • Neurosurgical Focus x
Clear All
Full access

Tetsuya Morimoto, Tomonori Yamada, Kiyoshi Nagata, Takeshi Matsuyama and Toshisuke Sakaki

Intramedullary enhancement of the cervical spinal cord is rare in chronic compression disease. An accompanying vascular lesion should be considered in such a case.

A 59-year-old man presented with severe cervical spondylotic myelopathy.

Gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) enhanced magnetic resonance imaging showed intramedullary enhancement at the C5`6 level, which was the most severely compressed level. A right ascending cervical arteriogram demonstrated a spinal arteriovenous fistula (AVF) fed mainly by the C-6 radicular artery and draining from the posterior medullary vein.

Surgery was performed to decompress the myelopathy and to obliterate the AVF. Postoperative MR imaging with Gd-DTPA enhancement showed immediate and complete disappearance of the previous enhancement. The intramedullary enhancement presumably resulted from the intraparenchymal hemodynamics due to the AVF.

Full access

Richard B. North, J. Paul McNamee, Lee Wu and Steven Piantadosi

Artificial neural networks are used increasingly in applications such as graphic pattern recognition, which are difficult to address with conventional statistical methods. In the management of chronic pain, graphic methods are used routinely; patients describe their patterns of pain using “pain drawings.” The authors have previously reported an automated, computerized pain drawing methodology, which has been used by patients with implanted spinal cord stimulators to represent a technical goal of the procedure, the overlap of pain by stimulation paresthesias. Standard linear discriminant statistical methods have shown associations between stimulation parameters and electrode positions as independent variables and technical outcome and relief of pain as dependent variables.

The authors have applied artificial neural networks to the problem of optimizing implanted stimulator adjustment. A data set of 3000 electrode combinations obtained in 41 patients was used to develop a linear discriminant statistical model on a mainframe computer and to train artificial neural networks on a personal computer. The performance of these two systems on a new data set obtained in 10 patients was compared with that of human “experts.” The best neural network model was marginally better than the linear discriminant model; the variance in patient ratings was predicted by these models to a degree that the human experts were unable to predict. The authors anticipate expanding the role of these models and incorporating them into expert sytems for clinical use.

Full access

Robert M. Levy

Careful preoperative screening of candidates for indwelling drug administration systems for the relief of intractable pain can help to exclude patients who will not benefit from this technology and predict efficacy in others. Unfortunately, bias on the part of both the treating physician and the patient can inappropriately skew the results of subjective or improperly controlled trials and lead to the implantation of drug administration systems in patients who will not benefit from chronic intrathecal narcotic administration.

The author and his coworkers have designed a quantitative, crossover, double-blind paradigm for screening patients who might otherwise be deemed eligible for chronic intraspinal narcotic administration. This paradigm has been used 31 times in 30 patients; based on the outcome of this testing, 22 patients (73%) underwent implantation of chronic infusion systems. Sixteen (80%) of 20 patients with pain related to cancer underwent pump implantation, whereas only six (60%) of the 10 patients with pain of nonmalignant origin were so treated. Sixteen of the patients (72%) have reported good to excellent relief after pump implantation; this includes 12 (75%) of the 16 patients with pain related to cancer and four (66%) of the six patients with pain of nonmalignant origin.

This screening paradigm thus appears to be both reliable and easily applied and promises to be of assistance in the selection of patients appropriate for this mode of therapy.

Full access

Charles H. Tator and Izumi Koyanagi

Vascular injury plays an important role in the primary and secondary injury mechanisms that cause damage to the acutely traumatized spinal cord. To understand the pathophysiology of human spinal cord injury, the authors investigated the vascular system in three uninjured human spinal cords using silicone rubber microangiography and analyzed the histological findings related to vascular injury in nine acutely traumatized human spinal cords obtained at autopsy. The interval from spinal cord injury to death ranged from 20 minutes to 9 months. The microangiograms of the uninjured human cervical cords demonstrated new information about the sulcal arterial system and the pial arteries. The centrifugal sulcal arterial system was found to supply all of the anterior gray matter, the anterior half of the posterior gray matter, approximately the inner half of the anterior and lateral white columns, and the anterior half of the posterior white columns. Traumatized spinal cord specimens in the acute stage (3-5 days postinjury) showed severe hemorrhages predominantly in the gray matter, but also in the white matter. The white matter surrounding the hemorrhagic gray matter showed a variety of lesions, including decreased staining, disrupted myelin, and axonal and periaxonal swelling. The white matter lesions extended far from the injury site, especially in the posterior columns. There was no evidence of complete occlusion of any of the larger arteries, including the anterior and posterior spinal arteries and the sulcal arteries. However, occluded intramedullary veins were identified in the degenerated posterior white columns. In the chronic stage (3-9 months postinjury), the injured segments showed major tissue loss with large cavitations, whereas both rostral and caudal remote sites showed well-demarcated necrotic areas indicative of infarction mainly in the posterior white columns. Obstruction of small intramedullary arteries and veins by the initial mechanical stress or secondary injury mechanisms most likely produced these extensive white matter lesions. Our studies implicate damage to the anterior sulcal arteries in causing the hemorrhagic necrosis and subsequent central myelomalacia at the injury site in acute spinal cord injury in humans.

Full access

Richard Kim, Ron Alterman, Patrick J. Kelly, Enrico Fazzini, David Eidelberg, Alaksandar Beric and Djorje Sterio

Unilateral pallidotomy is a safe and effective treatment for medically refractory bradykinetic Parkinson's disease, especially in those patients with levodopa-induced dyskinesia and severe on-off fluctuations. The efficacy of bilateral pallidotomy is less certain.

The authors completed 11 of 12 attempted bilateral pallidotomies among 150 patients undergoing pallidotomy at New York University. In all but one patient, the pallidotomies were separated by at least 9 months. Patients were selected for bilateral pallidotomy if they exhibited bilateral rigidity, bradykinesia, or levodopa-induced dyskinesia prior to treatment or if they exhibited disease progression contralateral to their previously treated side.

The Unified Parkinson's Disease Rating Scale (UPDRS) and timed upper-extremity tasks of the Core Assessment Protocol for Intracerebral Transplantation (CAPIT) were administered to all 12 patients in the “off” state (12 hours without receiving medications) preoperatively and again at 6 and 12 months after each procedure. The median UPDRS and contralateral CAPIT scores improved 60% following the initial procedure (p = 0.008, Wilcoxon rank sums test). The second pallidotomy generated only an additional 10% improvement in the UPDRS and CAPIT scores ipsilateral to the original procedure (p = 0.05). Worsened speech was observed in two cases. In the 12th case, total speech arrest was noted during test stimulation. Speech returned within minutes after stimulation was halted. Lesioning was not performed.

These results indicate that bilateral pallidotomy has a narrow therapeutic window. Motor improvement ipsilateral to the first lesion leaves little room for further improvement from the second lesion and the risk of speech deficit is greatly enhanced. Chronic pallidal stimulation contralateral to a previously successful pallidotomy may prove to be a safer alternative for the subset of patients who require bilateral procedures.

Full access

Alexander I. Tröster, Julie A. Fields, Steven B. Wilkinson, Karen Busenbark, Edison Miyawaki, John Overman, Rajesh Pahwa and William C. Koller

One theoretical advantage of chronic thalamic stimulation compared with thalamotomy for the treatment of refractory Parkinson's disease (PD) entails the avoidance and reversibility of potential cognitive morbidity. Support for the cognitive safety of thalamic stimulation remains largely anecdotal; empirical data are limited to the neuropsychological findings published for one small series of patients. The purpose of this study was to supplement those published findings that pertain to the mean changes in neuropsychological test scores and to extend previous findings by evaluating cognitive changes in individual cases from preoperative baseline to 4 months after electrode implantation. Nine patients with tremor-dominant, refractory PD underwent unilateral implantation of a deep brain stimulating electrode in the ventralis intermedius thalamic nucleus (five patients on their left and four patients on their right sides). A neuropsychological test battery was administered to each patient to evaluate attention, language, memory, and visuoperceptual and executive functions during their best “on” state before surgery, while on a medication regimen, and with the stimulator turned on after surgery. As a group, the patients attained significantly higher scores on word list recognition (discriminability) and delayed recall of prose passages after surgery than before surgery. In addition, there was a trend toward higher scores on a visual confrontation naming test after surgery. Examination of individual patient data indicated gains and losses in test scores exceeding two standard deviations to be very rare. Changes of one standard deviation were also relatively rare, but gains were more likely to occur than losses. These observations provide preliminary support for the cognitive safety of thalamic stimulation for PD.

Full access

Jeffrey E. Thomas

Chronic delayed cerebral vasospasm (CDCV) remains a serious and often fatal complication of aneurysmal subarachnoid hemorrhage (SAH). The current understanding of its fundamental mechanisms and molecular biological characterization is rudimentary. Two important vasoactive substances have been implicated in CDCV: endothelin-1 (ET-1) and nitric oxide (NO). A 21-amino acid vasoconstrictor peptide, ET-1 has generated interest as a possible important contributor to cerebral vasospasm on the basis of both clinical and experimental evidence suggesting abnormally enhanced production. Nitric oxide is a cell membrane-permeable free radical gas that accounts for the vasodilatory effect of endothelium-derived relaxation factor and is a physiological antagonist of ET-1. As with ET-1, abnormalities of NO production have been implicated in several pathological conditions including cerebral vasospasm. This brief report reviews some of the physiological and regulatory features of these two molecules and explores the possibility of their relationship to cerebral vasospasm.

Full access

Giuseppe Cinalli, Christian Sainte-Rose, Eve Marie Kollar, Michel Zerah, Francis Brunelle, Paul Chumas, Eric Arnaud, Daniel Marchac, Alain Pierre-Kahn and Dominique Renier

Object

A retrospective study of 1727 cases of craniosynostosis was undertaken to determine the interrelationship between abnormal cerebrospinal fluid (CSF) hydrodynamics and craniosynostosis.

Methods

The patients were divided intwo two groups: nonsyndromic craniosynostosis and syndromic craniosynostosis. Cases of occipital plagiocephaly without suture synostosis and cases of shunt-induced craniosynostosis were excluded from the study. The majority of patients (1297) were treated surgically for their cranial deformity; 95% of these patients had a postoperative follow-up review lasting 5 years. Clinical and radiographic charts covering the time from presentation through the follow-up period were reviewed.

Conclusions

Abnormal intracranial CSF hydrodynamics was found in 8.1% of the patients (3.4% of whom had received shunts and 4.5% of whom had not). Three types of CSF hydrodynamic disturbance were observed: progressive hydrocephalus with ventricular dilation, nonprogressive ventriculomegaly, and dilation of the subarachnoid spaces. Hydrocephalus occurred much more frequently in patients with syndromic craniosynostosis (12.1%) than in those with isolated craniosynostosis (0.3%). In fact, patients with kleeblattschädel exhibited hydrocephalus as a constant feature and patients with Crouzon's syndrome were far more likely to have hydrocephalus than those with other syndromes. In Apert's syndrome, ventricular dilation occurred very frequently, but it was almost always nonprogressive in nature. In most cases of syndromic craniosynostosis, venous sinus obstruction and/or chronic tonsillar herniation were found. Their role in the pathophysiology of hydrocephalus in craniosynostosis is discussed.

Full access

James A. Nitahara, Malou Valencia and Michael A. Bronstein

To define severity of illness to identify most effectively patients for whom admission to the intensive care unit (ICU) is unnecessary, the authors performed a retrospective cost-effectiveness analysis. The authors studied the records of 113 patients who were admitted to the ICU after undergoing laminectomy (or other spinal cord surgery) or craniotomy for removal of neoplasm; the Acute Physiology and Chronic Health Evaluation III prognostic system had identified these patients as having a 10% or less risk of requiring intervention while in the ICU. No patient required active intervention during a mean stay of 3.26 days in the ICU. Combined use of a “step-down” postoperative care unit and ICU can optimize allocation of medical resources while providing high-quality care for some neurosurgical patients who are at low risk of requiring postoperative intervention.

Full access

Yuichi Murayama, Fernando Viñuela, Gary R. Duckwiler, Y. Pierre Gobin and Guido Guglielmi

Guglielmi detachable coil (GDC) technology is a valuable therapeutic alternative to the surgical treatment of ruptured or incidental intracranial aneurysms. The authors describe their technical and clinical experience in the utilization of the GDC technique in patients who underwent endovascular occlusion for the treatment of incidentally found intracranial aneurysms.

One hundred fifteen patients with 120 incidentally found intracranial aneurysms underwent embolization using the GDC endovascular technique. Ninety-one patients were female and 24 were male. Patient age ranged from 13 to 80 years. In 64 patients the incidental aneurysms were discovered when unrelated nonneurological conditions indicated the need for angiography or magnetic resonance angiography (Group 1). Twenty patients who presented with incidental aneurysms that were discovered during treatment for an acutely ruptured aneurysm were treated in the acute phase of subarachnoid hemorrhage (SAH) (Group 2). Sixteen patients with incidental aneurysms were treated during the chronic phase of SAH (Group 3). Group 4 included 15 patients who had incidental aneurysms associated with brain tumors or arteriovenous malformations.

Angiographic results showed complete or near complete occlusion in 109 aneurysms (91%) and incomplete occlusion in five aneurysms (4%). Unsuccessful GDC embolization was attempted in six aneurysms (5%). One hundred nine patients (94.8%) remained neurologically intact or unchanged from initial clinical status. Five patients (4.3%) deteriorated due to immediate procedural complications (overall immediate morbidity rate). All of these complications occurred in the first 50 patients treated earlier in this series. No clinical complications were observed in the last 65 patients. Follow-up cerebral angiograms were obtained in 77 patients with 79 aneurysms. The median clinical follow-up period was 16.3 months.

No recanalization was observed in the 52 completely occluded aneurysms. Of the 22 aneurysms with small neck remnants, eight (36%) showed further thrombosis, 7 (32%) remained anatomically unchanged, and seven (32%) showed recanalization due to compaction of the coils. In one patient, a partially embolized aneurysm ruptured 3 years postembolization. In Groups 1 and 3, the average length of hospitalization was 3.3 days.

The evolution of the GDC technology has proved to provide safe treatment of incidental aneurysms (a morbidity rate of 0% was achieved in the last 65 patients). The topography of the aneurysm and the clinical condition of the patient did not influence final anatomical or clinical outcomes. The GDC technology also confers a positive economical impact by decreasing hospital length of stay and by eliminating the need for postembolization intensive care unit care.