Showing papers in "Neurosurgery in 1996"

Glioma invasion in the central nervous system.

Abstract: Invading glioma cells seem to follow distinct anatomic structures within the central nervous system. Tumor cell dissemination may occur along structures, such as the basement membranes of blood vessels or the glial limitans externa, that contain extracellular matrix (ECM) proteins. Frequently, invasive glioma cells are also found to migrate along myelinated fiber tracts of white matter. This behavior is most likely a consequence of using constitutive extracellular ligands expressed along the pathways of preferred dissemination. The extracellular space in anatomic structures, such as blood vessel basement membranes or between myelinated axons, is profoundly different, thus suggesting that glioma cells may be able to use a multiplicity of matrix ligands, possibly activating separate mechanisms for invasion. In addition, enzymatic modification of the extracellular space or deposition of ECM by the tumor cells may also create a more permissive environment for tumor spread into the adjacent brain. Tumor cell invasion is defined as translocation of neoplastic cells through host cellular and ECM barriers. This process has been studied in other cancers, in which a cascade of events has been described that involves receptor-mediated matrix adhesion, degradation of matrix by tumor-secreted metalloproteinases, and, subsequently, active cell locomotion into the newly created space. Although some of these mechanisms may play an important role in glioma invasion, there are some significant differences that are mainly the result of the profoundly different composition of the extracellular environment within the brain. This review focuses on the composition of central nervous system ECM and the recent evidence for the use by glioma cells of multiple invasion mechanisms in response to this unique environment.

Segments of the internal carotid artery: a new classification.

Abstract: This study proposes an anatomically based nomenclature for the internal carotid artery (ICA) that can be applied by all disciplines. In 1938, Fischer published a seminal paper describing five segments of the ICA that were designated C1 through C5. These segments were based on the angiographic course of the intracranial ICA rather than its arterial branches or anatomic compartments. Subsequent attempts to apply modern nomenclature to these numerical segments failed to recognize Fischer's original intent of describing patterns of arterial displacement by tumors and, therefore, resulted in a nomenclature that was anatomically inaccurate. Fischer's system was further limited, because segments were numbered opposite the direction of blood flow and the extracranial ICA was excluded. The authors propose a new classification, which includes the entire ICA, uses a numerical scale in the direction of blood flow, and describes the segments of the ICA according to a detailed understanding of the anatomy surrounding the ICA and the compartments through which it travels. Twenty cadaveric specimens with intravascular injection of silicone rubber were used for microscopic dissection and 20 dry skulls were inspected. Histological sections in critical areas were examined. The authors' classification has the following seven segments: C1, cervical; C2, petrous; C3, lacerum; C4 cavernous; C5, clinoid; C6, ophthalmic; and C7, communicating. This classification is practical, accounts for new anatomic information and clinical interests, and clarifies all segments of the ICA.

Proliferative Activity and Invasiveness among Pituitary Adenomas and Carcinomas: An Analysis Using the MIB-1 Antibody

Abstract: Although histologically benign, one-third of all pituitary tumors will be invasive of surrounding structures. In this study, the relationship between the proliferative activity in pituitary adenomas and their invasiveness was investigated. Invasion was defined as gross, operatively or radiologically apparent infiltration of dura or bone. Using the recently developed MIB-1 monoclonal antibody, which recognizes the Ki-67 cell cycle-specific nuclear antigen, the growth fractions of 37 noninvasive adenomas, 33 invasive adenomas, and 7 primary pituitary carcinomas were determined. All tumors were fully classified by histology, immunohistochemistry, and electron microscopy. The mean Ki-67 -derived growth fractions for noninvasive adenomas, invasive adenomas, and pituitary carcinomas were 1.37 +/- 0.15%, 4.66 +/- 0.57%, and 11.91 +/- 3.41%, respectively (mean +/- standard error of the mean). An analysis of variance and then individual pairwise comparisons confirmed significant differences in the mean Ki-67 labeling index between each of the three tumor groups (P < 0.01). The mean growth fraction of hormonally active pituitary adenomas (3.25 +/- 0.26%) was significantly higher than that for nonfunctioning adenomas (2.06 +/- 0.23%) (P = 0.03). Establishing a threshold labeling index of 3% served to distinguish invasive from noninvasive adenomas with 97% specificity and 73% sensitivity and was associated with positive and negative predictive values of 96 and 80%, respectively. Although invasive pituitary tumors exhibited significantly higher growth fractions than did noninvasive tumors, there were individual exceptions, indicating that in a subpopulation of invasive pituitary tumors, factors other than proliferative activity determine invasive potential.

Neuropsychological functioning and recovery after mild head injury in collegiate athletes

Abstract: OBJECTIVE:This study prospectively examined neuropsychological functioning in 2300 collegiate football players from 10 National Collegiate Athletic Association Division A universities. The study was designed to determine the presence and duration of neuropsychological symptoms after mild head injury

Association Between Peridural Scar and Recurrent Radicular Pain After Lumbar Discectomy: Magnetic Resonance Evaluation

Abstract: THE PURPOSE OF this study was to investigate the presence of any correlation between recurrent radicular pain during the first six months following first surgery for herniated lumbar intervertebral disc and the amount of lumbar peridural fibrosis as defined by MR imaging. 197 patients who underwent first-time single-level unilateral discectomy for lumbar disc herniation were evaluated in a randomized, double-blind, controlled multicenter clinical trial. Clinical assessments, performed by physicians blinded to patient treatment status, were conducted preoperatively and at one and six months postoperatively. The enhanced MR images of the operative site utilized in the analysis were obtained at six months postoperatively. Radicular pain was recorded by the patient using a validated visual analog pain scale in which 0 = no pain and 10 = excruciating pain. The data obtained at the 6 month time point were analyzed for an association between amount of peridural scar as measured by MR imaging and clinical failure as defined by the recurrence of radicular pain. The results showed that the probability of recurrent pain increases when scar score increases. Patients having extensive peridural scar were 3.2 times more likely to experience recurrent radicular pain than those patients with less extensive peridural scarring. In conclusion, this prospective, controlled, randomized, blinded, multicenter study has demonstrated that there is a significant association between the presence of extensive peridural scar and the occurrence of recurrent radicular pain.

Revascularization and aneurysm surgery: current techniques, indications, and outcome.

Abstract: Revascularization is an important component of treatment for complex aneurysms that cannot be directly clipped and instead require parent vessel occlusion. A consecutive series of 61 patients with 63 aneurysms requiring cerebral revascularization is presented. Aneurysms were located along the petrous internal carotid artery (ICA) (n = 5), the cavernous ICA (n = 16), the supraclinoid ICA (n = 12), the middle cerebral artery (n = 17), the anterior cerebral artery (n = 4), the vertebral artery/posterior inferior cerebellar artery (n = 5), and the midbasilar artery (n = 4). Aneurysms were treated by direct clipping (n = 8), trapping (n = 28), proximal vessel occlusion (n = 9), distal vessel occlusion (n = 1), excision (n = 15), and thrombotic occlusion (n = 2). Revascularization was performed with petrous to supraclinoid ICA bypass (n = 12), superficial temporal artery to middle cerebral artery bypass (n = 15), superficial temporal artery to middle cerebral artery bypass with saphenous graft (n = 5), superficial temporal artery to superior cerebellar artery bypass (n = 4) long saphenous bypass (n = 11), in situ bypass (n = 3), and primary reanastomosis (n = 13). Fifty-seven patients (93%) had good outcomes, and one patient died (surgical mortality, 2%). This experience demonstrates that revascularization can be performed with low morbidity and mortality. We think that the cumulative risks of not performing revascularization in patients who tolerate ICA balloon occlusion exceed the surgical risk of revascularization. We therefore favor revascularization in patients with complex aneurysms treated by surgical arterial occlusion.

Continuous monitoring of partial pressure of brain tissue oxygen in patients with severe head injury

Abstract: Ischemia is one of the major factors causing secondary brain damage after severe head injury. We have investigated the value of continuous partial pressure of brain tissue oxygen (PbrO2) monitoring as a parameter for cerebral oxygenation in 22 patients with severe head injury (Glasgow Coma Scale score, < or = 8). Jugular bulb oxygenation, intracranial pressure, and cerebral perfusion pressure were simultaneously recorded. O2 and CO2 reactivity tests were performed daily to evaluate oxygen autoregulatory mechanisms. PbrO2 monitoring was started an average of 7.0 hours after trauma with a mean duration of 74.3 hours. No complications were seen, and the calibration of the catheters after measurement showed a zero drift of 1.2 +/- 0.8 mm Hg and a sensitivity drift of 9.7 +/- 5.3%. In 86% of patients, PbrO2 was < 20 mm Hg in the acute phase. Mean PbrO2 significantly increased during the first 24 hours after injury. Two distinct patterns of change of PbrO2 over time were noted. The first pattern was characterized by normal stable levels after 24 hours, and the second was characterized by transiently elevated levels of PbrO2 during the second and third days. PbrO2 values < or = 5 mm Hg within 24 hours after trauma negatively correlated with outcome. O2 reactivity was significantly lower in patients with good outcomes. CO2 reactivity showed no constant pattern of change over time and was not correlated with outcome. Increased hyperventilation was shown to decrease PbrO2 in some patients. Accurate detection of the moment of cerebral death was possible on the basis of the PbrO2 measurements. The correlation between PbrO2 and other parameters, such as intracranial pressure and cerebral perfusion pressure, was weak. We conclude that PbrO2 monitoring is a safe and clinically applicable method in patients with severe head injury. The early occurrence of ischemia after head injury can be monitored on a continuous basis. Deficiency of oxygen autoregulatory mechanisms can be demonstrated, and their occurrence is inversely related to outcome. For practical clinical use, the method seemed to be superior to jugular oximetry.

Operative treatment of spontaneous spinal epidural hematomas : a study of the factors determining postoperative outcome

Abstract: OBJECTIVE: We clarify the factors affecting postoperative outcomes in patients who have suffered spontaneous spinal epidural hematomas. METHODS: We review 330 cases of spontaneous spinal epidural hematomas from the international literature and three unpublished cases of our own. Attention was focused on sex, age, medical history, mortality, size and position of the hematoma, vertebral level of the hematoma, preoperative neurological condition, operative interval, and postoperative result. RESULTS: Sex, age, and size and position of the hematoma did not correlate with postoperative outcome. Mortality correlated highly with cervical or cervicothoracic hematomas, especially in patients with cardiovascular disease and those undergoing anticoagulant therapy. Incomplete preoperative sensorimotor deficit correlated highly with favorable outcomes (P < 0.0005), and recovery was significantly better when decompression was performed in < or = 36 hours in patients with complete sensorimotor loss (P < 0.05) and in < or = 48 hours in patients with incomplete sensorimotor deficit (P < 0.005). CONCLUSION: The critical factors for recovery after spontaneous spinal epidural hematoma are the level of preoperative neurological deficit and the operative interval. The vertebral level of the hematoma did not correlate with postoperative results, which suggests that local compression, rather than vascular obstruction, is the main factor in producing neurological deficit.

Epidemiology of Brachial Plexus Injuries in a Multitrauma Population

Abstract: OBJECTIVE: The purpose was to identify the prevalence, causative factors, injury types, and associated injury patterns in multitrauma patients who sustained brachial plexus injuries. METHODS: A retrospective review of a prospectively collected and computerized database and a chart review were performed. RESULTS: Brachial plexus injuries were identified in 54 of 4538 (1.2%) patients presenting to a regional trauma facility. Young male patients predominated. Motor vehicle accidents were the most frequent cause overall, but only 0.67% of such accidents resulted in plexus injuries. Conversely, 4.2% of motorcycle accident victims and 4.8% of snowmobile accident victims suffered brachial plexus injuries. Injuries were supraclavicular for 62% of patients and infraclavicular for 38%. Supraclavicular injuries were more likely to be severe (Sunderland Grade 3 or 4), compared with infraclavicular injuries, which were neurapraxic in 50% of cases (P Language: en

Growth, subsequent bleeding, and de novo appearance of cerebral cavernous angiomas.

Abstract: In a series of 145 patients with brain cavernous angiomas treated at our hospital in the last 16 years, the angiomas of 18 patients exhibited aggressive biological behavior characterized by recurrent overt bleeding, growth, or de novo appearance. The cavernomas were in the cerebellum in three patients, in the brain stem in one, in the thalamus in four, in the caudate nucleus in two, in the diencephalon in one, and in the white matter of the cerebral hemispheres in seven. Three of these patients suffered from the familial or multiple form of the disease, two were pregnant, three had previously been irradiated for other tumors, and one had been treated by radiosurgery in the past. Overall, new cavernous malformations not previously shown were discovered in six patients. In 10 patients (3 male and 7 female) presenting with recurrent hemorrhages, the mean period of time between bleedings was 11 months (range, 1 wk-3 yr). Eleven patients were treated by definitive surgery, and seven were conservatively treated. One patient with a diencephalic cavernoma died from progressive hypothalamic dysfunction; three patients in the nonsurgical group had repeated symptoms and were left with additional neurological deficits. The outcome of the surgical group was the same (seven patients) or improved (four patients). Risk factors favoring an aggressive behavior included pregnancy, familial or multiple form of the disease, previous whole brain or stereotactic radiotherapy, incomplete removal, brain location, and associated venous malformation. The female preponderance (female to male ratio, 13:5) may also suggest some role of hormonal factors in influencing the biological behavior of cavernous malformations.

Normal and Abnormal Calcium Homeostasis in Neurons: A Basis for the Pathophysiology of Traumatic and Ischemic Central Nervous System Injury

Abstract: CLINICAL RECOVERY AFTER central nervous system (CNS) trauma or ischemia may be limited by a neural injury process that is triggered and perpetuated at the cellular level, rather than by a lesion amenable to surgical repair. It is widely thought that one such process, a fundamental pathological mechanism initiated by CNS injury, is a disruption of cellular Ca 2+ homeostasis. Because of the critical role of Ca 2+ ions in regulating innumerable cellular functions, this major homeostatic disturbance is thought to trigger neuronal and axonal degeneration and produce clinical disability. We review those aspects of normal and pathological Ca 2+ homeostasis in neurons that relate to neurodegeneration and to the application of neuroprotective strategies for the treatment of CNS injury. In particular, we examine the contribution of Ca 2+ -permeable ionic channels, Ca 2+ pumps, intracellular Ca 2+ stores, intracellular Ca 2+ buffering systems, and the roles of secondary, Ca 2+ -dependent processes in neurodegeneration. A number of hypotheses linking Ca 2+ ions and Ca 2+ permeable channels to neurotoxicity are discussed with an emphasis on strategies for lessening Ca 2+ -related damage. A number of these strategies may have a future role in the treatment of traumatic and ischemic CNS injury.

Recurrence of cranial base meningiomas

Abstract: OBJECTIVE Long-term data on the natural history of traditionally treated cranial base meningiomas are necessary to judge the benefit of modern cranial base techniques for individual patients and to understand when nonradical surgery of a meningioma is in the interest of the patient. The only available means of obtaining such data is investigation of patients treated before the present surgical era. METHODS The records of 315 patients who were operated on at Karolinska Hospital between January 1, 1947, and December 31, 1982, were reviewed. Of the patients, 10.8% died perioperatively and 9.7% died within 10 years. The remaining patients were followed for 10 to 36 years (mean, 18 yr). RESULTS The 5-year recurrence rate was 4% for patients undergoing radical surgery (Grades 1 and 2) and 25 to 45% for patients undergoing Grade 3 or 4 operations. Follow-up periods longer than 5 years revealed that 16% of Grade 1 and 20% of Grade 2 patients had symptomatic recurrences, whereas a majority of Grade 4 and 5 patients showed symptomatic progression. Forty-two of 69 patients who underwent Grade 4 or 5 operations died as a result of their tumors, usually within 10 years after the first operation. No patients who underwent Grade 4 or 5 operations were free from symptomatic progression after 20 years. The tumor progression or recurrence was usually detected within the 1st 10 years, but late recurrences were seen < or = 25 years after the operation. The worst outcome was found in medial sphenoid wing/clinoidal meningiomas and in tumors invading the cavernous sinus. Subfrontal tumors showed unexpectedly high recurrence rates, with a mortality rate < or = 14% in the late phase. CONCLUSION The findings emphasized the necessity to plan the management of patients with cranial base meningiomas according to a 10- to 20-year perspective. Patients must be followed to evaluate the treatment results and to detect recurrences. Nonradical surgery must be viewed as a temporizing or palliative measure; a continued search for means of radical tumor treatment is warranted in these often surgically difficult tumors.

Somatosensory evoked potential phase reversal and direct motor cortex stimulation during surgery in and around the central region.

Abstract: In 99 patients with mass lesions in and around the central region, the central sulcus was intraoperatively localized with the use of somatosensory evoked potential (SEP) phase reversal. In 33 of these patients, the motor cortex was directly stimulated and electromyographic responses were recorded from the forearm flexor, thenar, and hypothenar muscles. An additional 25 patients, with subcortical lesions or lesions directly located at the pyramidal tract, were continuously monitored during surgery by motor evoked potentials (MEPs). An exact determination of the central sulcus and tumor localization was possible in all patients; a phase reversal was obtained in 90.8% of the patients, and localization was possible as a result of anatomic structures and the loss of N20 or P20 of SEPs in the other 9.2%. MEPs were obtained in 32 of 33 patients and also in all 25 patients who underwent MEP monitoring at the beginning of tumor removal. From this study, it can be concluded that the combination of SEP phase reversal and modified electrical cortex stimulation is compatible with general anesthesia, although anesthesia was not systematically controlled according to a protocol. Although this study demonstrates that the combined SEP/MEP technique was feasible, it is not yet possible to demonstrate benefit in improving the outcome of patients. Concerning the safety of stimulation, the exact localization of the central sulcus by the noninvasive SEP method, compared with direct electrical stimulation, offered more safety for the patient. The modified technique of direct motor cortex stimulation needed much less charge density than did the common technique. The recording of electromyographic responses instead of movements made objective documentation possible, and the analysis of amplitudes and latencies will supply quantitative information about the motor system.

Functional cortex and subcortical white matter located within gliomas.

Abstract: Some neurosurgeons state that intra-axial tumors may be resected with a low risk of neurological deficit if the tumor removal stays within the confines of the grossly abnormal tissue. This is thought to be so even when the lesion is presumably located in a functional area, providing that the adjacent normal-appearing cortex and subcortical white matter are not disturbed. This retrospective analysis presents evidence that this view is not always correct, because functioning motor, sensory, or language tissue can be located within a grossly obvious tumor or the surrounding infiltrated brain. Intraoperative stimulation mapping techniques identified 28 patients, ranging in age between 22 and 73 years, who showed evidence of functional tissue within the boundaries of infiltrative gliomas, as identified by correlation with computed tomography and magnetic resonance imaging scans, intraoperative ultrasound, gross visualization, and histological confirmation. Direct stimulation mapping of cortical and subcortical portions of the tumor during resections identified motor, sensory, naming, reading, or speech arrest function. Nineteen patients had new or worsened neurological deficits immediately after the operation, but after 3 months, only 6 continued to show new deficits whereas 18 showed no deficits and 2 improved. These results demonstrate that regardless of the degree of tumor infiltration, swelling, apparent necrosis, and gross distortion by the mass, functional cortex and subcortical white matter may be located within the tumor or the adjacent infiltrated brain. Therefore, to safely maximize glioma resection in these functional areas, intraoperative stimulation mapping may be used to identify functional cortical or subcortical tissue within, as well as adjacent to, the tumor, thus avoiding permanent injury.

Release of gamma-aminobutyric acid in the dorsal horn and suppression of tactile allodynia by spinal cord stimulation in mononeuropathic rats.

Abstract: OBJECTIVE The aim of the present study is to monitor the extracellular gamma-aminobutyric acid (GABA) levels in the lumbar dorsal horn of allodynic rats, which respond to spinal cord stimulation (SCS) with a normalization of the tactile withdrawal threshold. In addition, we monitored the GABA levels in nonresponding and sham-stimulated rats. METHODS Partial constriction injury of the sciatic nerve was performed, and a permanent electrode for SCS was inserted into the spinal canal. The response to SCS was assessed with von Frey hairs in awake animals. Later, microdialysis was performed in the dorsal horn of the spinal cord under halothane anesthesia. The concentration of GABA in the microdialysate was assessed by high-performance liquid chromatography. RESULTS Extracellular GABA levels in rats with sciatic nerve lesions and allodynia (2.3 +/- 0.5 nmol/L) were significantly lower (P < 0.001) than in control rats with intact sciatic nerves (8.1 +/- 1.0 nmol/L), whereas only slightly decreased GABA levels (5.7 +/- 1.1 nmol/L) were detected in nonallodynic rats with sciatic nerve lesions. In the allodynic rats, which respond to SCS by a normalization of the tactile withdrawal threshold, significantly (P < 0.001) increased GABA levels (6.7 +/- 2.3 nmol/L) were detected after SCS. In contrast, neither the allodynic rats, which did not respond to SCS, nor the sham-stimulated allodynic rats displayed increased GABA levels in response to stimulation. CONCLUSION Our results indicate that the development of allodynia, a common symptom in neuropathic pain states, may be linked to a decreased spinal release of GABA. We suggest that an SCS-induced release of GABA could be important for the suppression of allodynia observed in rats after SCS. Similar mechanisms could also be involved in the SCS-induced alleviation of pain in patients with peripheral neuropathy.

p53 Expression in Pituitary Adenomas and Carcinomas: Correlation with Invasiveness and Tumor Growth Fractions

Abstract: Although most pituitary tumors are well differentiated, histologically benign neoplasms, their clinical behavior is known to vary greatly. These lesions are relentlessly aggressive in some instances yet biologically indolent in others, but these prognostically relevant differences in behavior are not reflected in their histopathological appearance. As a means of identifying intrinsically aggressive pituitary tumors, we evaluated 70 pituitary adenomas and 7 primary pituitary carcinomas for their expression of the p53 gene product, a nuclear phosphoprotein whose immunohistochemical accumulation has served as an unfavorable prognostic factor for a wide range of human neoplasms. All tumors were fully classified by immunohistochemistry and electron microscopy; adenomas were further stratified on the basis of their invasion status, the latter being defined as gross operatively or radiologically apparent infiltration of dura or bone. Conclusive nuclear immunopositivity for p53 was identified in a total of 12 tumors, all being either invasive adenomas or primary pituitary carcinomas. A clear and highly significant association was evident between p53 expression and tumor behavior, as the proportion of p53-positive cases among noninvasive adenomas, invasive adenomas, and pituitary carcinomas was 0, 15.2, and 100%, respectively (chi 2 = 44.72; degrees of freedom, 2; P << 0.001). A comparison of previously reported growth fraction data with p53 expression indicated that the mean Ki-67-derived growth fraction of p53-positive tumors was significantly higher than that of p53-negative tumors (10.41 +/- 2.20 versus 2.51 +/- 0.28%) (+/- standard error of the mean, two-sample t test for independent samples, P = 0.004). There was no apparent relationship between the functional status of the tumor and p53 expression; positivity was observed among somatotroph, lactotroph, corticotroph, and clinically nonfunctioning pituitary tumors. These data indicate that p53 expression, when conclusively present in pituitary tumors, may be of some diagnostic usefulness as a marker of biologically aggressive behavior.

Effects of medulloblastoma resections on outcome in children: a report from the Children's Cancer Group.

Abstract: We reviewed the data of children with high-stage primitive neuroectodermal tumors (medulloblastomas) who were treated on Children's Cancer Group-921 protocol to evaluate the correlation between tumor resection and prognosis. Patients enrolled in the study had either tumors that were operatively categorized to be Chang tumor stage 3b or 4, postoperative residual tumors > 1.5 cm2, or evidence of tumor dissemination (Chang metastasis Stages [M Stages] 1-4) at diagnosis. Resections were analyzed in two ways, as follows: 1) by the extent of resection (percent of the tumor that was removed), as estimated by the treating neurosurgeon; and 2) by the extent of residual tumor (how much of the tumor was left), as estimated from postoperative scans. Two hundred and three children were enrolled in the study with institutional diagnoses of primitive neuroectodermal tumors-medulloblastomas; diagnoses were confirmed by central neuropathological review in 188 patients. Progression-free survival (PFS) at 5 years was 54% (standard error, 5%). As in previous Children's Cancer Group studies, age and M stage correlated with survival; PFS was significantly lower in children 1.5 to 3.0 years old at diagnosis and in those with any evidence of tumor dissemination (M Stage 1-4). On univariate analysis, neither extent of resection nor extent of residual tumor correlated with PFS. However, adjusting for other factors, extent of residual tumor was important; PFS was 20% (standard error, 14%) better at 5 years in children with no dissemination (M Stage 0) who had 3 years old with no tumor dissemination (M Stage 0) and with 3 years old, with no tumor dissemination). In contrast to age and M stage, the major factors associated with outcome, residual tumor is an important variable in outcome, one that neurosurgeons can control.

Hemorrhage risk after stereotactic radiosurgery of cerebral arteriovenous malformations.

Abstract: TO ANALYZE THE effect of stereotactic radiosurgery on the hemorrhage rate of arteriovenous malformations (AVMs), we reviewed the clinical and angiographic characteristics of 315 patients with AVMs before and after radiosurgery. One hundred ninety-six patients sustained 263 bleeds in 10,939 patient-y

Comparison of surgical treatments for trigeminal neuralgia: reevaluation of radiofrequency rhizotomy.

Abstract: In this study, we reevaluate the results of radiofrequency rhizotomy and review the effectiveness of other surgical procedures for the treatment of trigeminal neuralgia. Five hundred patients with trigeminal neuralgia underwent radiofrequency rhizotomy at the University of Cincinnati Medical Center, Cincinnati, OH, between 1981 and 1986. Their results are compared with those of patients reported in the literature who underwent radiofrequency rhizotomy (6205 patients), glycerol rhizotomy (1217 patients), balloon compression (759 patients), microvascular decompression (MVD) (1417 patients), and partial trigeminal rhizotomy (250 patients). Comparisons were based on the following outcome parameters: technical success, pain relief and recurrence, facial numbness, dysesthesia, corneal anesthesia, keratitis, trigeminal motor dysfunction, permanent cranial nerve deficit, intracranial hemorrhage or infarction, perioperative morbidity, and perioperative mortality. We found that MVD had the lowest rate of technical success. Radiofrequency rhizotomy and MVD had the highest rates of initial pain relief and the lowest rates of pain recurrence. Glycerol rhizotomy had the highest rate of pain recurrence. Balloon compression had the highest rate of trigeminal motor dysfunction. Balloon compression and MVD had the lowest rates of corneal anesthesia or keratitis. MVD had the lowest rates of facial numbness and dysesthesia. All percutaneous procedures had similar rates of dysesthesia. Posterior fossa exploration had the highest rates of permanent cranial nerve deficit, intracranial hemorrhage or infarction, and perioperative morbidity and mortality. On the basis of our experience and a review of the literature, we conclude the following: 1) percutaneous techniques and posterior fossa exploration offer advantages and disadvantages, 2) radiofrequency rhizotomy is the procedure of choice for most patients undergoing first surgical treatments, and 3) MVD is recommended for healthy patients who have isolated pain in the first ophthalmic trigeminal division or in all three trigeminal divisions and patients who desire no sensory deficit.

Association between peridural scar and recurrent radicular pain after lumbar discectomy: magnetic resonance evaluation. ADCON-L European Study Group.

Abstract: The purpose of this study was to investigate the presence of any correlation between recurrent radicular pain during the first six months following first surgery for herniated lumbar intervertebral disc and the amount of lumbar peridural fibrosis as defined by MR imaging. 197 patients who underwent first-time single-level unilateral discectomy for lumbar disc herniation were evaluated in a randomized, double-blind, controlled multicenter clinical trial. Clinical assessments, performed by physicians blinded to patient treatment status, were conducted preoperatively and at one and six months postoperatively. The enhanced MR images of the operative site utilized in the analysis were obtained at six months postoperatively. Radicular pain was recorded by the patient using a validated visual analog pain scale in which 0 = no pain and 10 = excruciating pain. The data obtained at the 6 month time point were analyzed for an association between amount of peridural scars as measured by MR imaging and clinical failure as defined by the recurrence of radicular pain. The results showed that the probability of recurrent pain increases when scar score increases. Patients having extensive peridural scar were 3.2 times more likely to experience recurrent radicular pain than those patients with less extensive peridural scarring. In conclusion, this prospective, controlled, randomized, blinded, multicenter study has demonstrated that there is a significant association between the presence of extensive peridural scar and the occurrence of recurrent radicular pain.

Analysis of 561 patients with 690 middle cerebral artery aneurysms: anatomic and clinical features as correlated to management outcome.

Abstract: In a series of 1314 consecutive patients with cerebral aneurysms from a defined catchment area in eastern Finland (870,000 inhabitants), 561 patients (43%) had middle cerebral artery aneurysms (MCAAs). One or more associated aneurysms were common; 221 patients with MCAAs (39%) had multiple intracranial aneurysms (MIA). In other words, three-fourths (73%) of all patients with MIA had at least one MCAA. Multiple MCAAs, found in 111 patients (20%), were common in this Finnish population. One hundred of these patients had bilateral MCAAs, of whom 63 had mirror aneurysms, that is, aneurysms at the same site but on different sides. Thirty-five patients had "pure" mirror aneurysms, that is, they did not have any other aneurysms. Most MCAAs (81%) were located at the bifurcation. Three-fourths (72%) of the proximal MCAAs were associated with MIA. Giant aneurysms were significantly more common as single MCAAs than as any other single aneurysm. The frequency of intracerebral hematomas (42%) was by far higher in patients with MCAAs than in patients with ruptured aneurysms at other sites. Most of the intracerebral hematomas occurred in patients with bifurcation MCAAs that pointed laterally. Patients with MCAAs had surprisingly bad management outcomes despite good surgical results in patients with good Hunt and Hess grades. There were significantly more poor outcomes (Glasgow Outcome Scale score, 3-5) among patients with ruptured MCAAs than among those with any other anterior circulation aneurysms (32 and 25%, respectively). Also, the multiplicity of aneurysms increased the risk for poor outcome, which occurred in 39% of the patients who had MIA with one MCAA and 37% of those who had multiple MCAAs. Epilepsy, severe hemiparesis, and visual field deficits were the most common disabilities in long-term survivors, associated far more frequently with MCAAs than with aneurysm at other sites.

The neuroimaging and clinical spectrum of neurofibromatosis 2.

Abstract: Neurofibromatosis 2 (NF2) is an autosomal dominant disease predisposing to multiple tumors of the central and peripheral nervous system. Bilateral vestibular schwannomas are the hallmark of the disease. To define the clinical spectrum of the disease, we performed gadolinium-enhanced magnetic resonance imaging of the brain and spine as well as neurological, dermatological, and ocular examinations in 48 patients with NF2 diagnosed with the National Institutes of Health diagnostic criteria. Patients were ascertained from patient workshops and publications and from referral as a result of vestibular schwannoma surgery. Vestibular schwannomas were found in 46 patients (96%, 43 bilateral and 3 unilateral), spinal tumors were found in 43 (90%), posterior subcapsular cataracts were found in 30 (63%), meningiomas were found in 28 (58%), and trigeminal schwannomas were found in 14 (29%). The presenting symptoms included hearing loss or tinnitus in 15 patients (31%), multiple or nonspecific symptoms in 15 (31%), skin tumors in 12 (25%), and ocular symptoms in 6 (13%). When the complete spine was imaged, spinal tumors were more common in patients with NF2 than has previously been reported. This is a noteworthy finding, because spinal tumors are a major cause of NF2 morbidity and mortality.

Variations in the natural history and survival of patients with supratentorial low-grade astrocytomas

Abstract: Data from 55 consecutive patients with low-grade astrocytomas treated between 1982 and 1990 were analyzed to determine specific outcome factors, including time to recurrence, incidence of anaplastic transformation, and survival. Gender, type of symptoms, contrast enhancement, and timing of radiation therapy were not significant in determining outcome. Patients who had symptoms for > 2 years and underwent gross-total resection of the tumor, with age as a continuous variable, were associated with significantly longer time to recurrence and survival. Within the population of patients with low-grade astrocytomas, patients with chronic epilepsy clearly had the best prognoses. There were no tumor recurrences or deaths in 27 patients with chronic epilepsy, regardless of the extent of surgery and without the use of radiotherapy. Ten-year survival was 100% for 31 patients who underwent gross-total tumor resection, regardless of the length of preoperative symptoms. Immediate postoperative radiotherapy did not prolong the time to recurrence, reduce the incidence of transition to more malignant tumors at recurrence, or increase the length of survival when compared with delayed radiotherapy. Because recurrence with a high-grade lesion caused 92% of the mortality in our series, the benefit in patients who underwent aggressive surgery seems to result from a significant decrease in the risk of recurrence when compared with patients who underwent anything less than gross-total resection. Our data also suggest that variability in the natural history of low-grade astrocytomas has a strong influence in determining survival and that tumors associated with chronic epilepsy are much less likely to become more malignant over time.

Functional Magnetic Resonance Imaging Mapping of the Motor Cortex in Patients with Cerebral Tumors

Abstract: Objective The purpose of this study was to determine the usefulness of functional magnetic resonance imaging (FMRI) to map cerebral functions in patients with frontal or parietal tumors. Methods Charts and images of patients with cerebral tumors or vascular malformations who underwent FMRI with an echoplanar technique were reviewed. The FMRI maps of motor (11 patients), tactile sensory (12 patients), and language tasks (4 patients) were obtained. The location of the FMRI activation and the positive responses to intraoperative cortical stimulation were compared. The reliability of the paradigms for mapping the rolandic cortex was evaluated. Results Rolandic cortex was activated by tactile tasks in all 12 patients and by motor tasks in 10 of 11 patients. Language tasks elicited activation in each of the four patients. Activation was obtained within edematous brain and adjacent to tumors. FMRI in three cases with intraoperative electrocortical mapping results showed activation for a language, tactile, or motor task within the same gyrus in which stimulation elicited a related motor, sensory, or language function. In patients with > 2 cm between the margin of the tumor, as revealed by magnetic resonance imaging, and the activation, no decline in motor function occurred from surgical resection. Conclusions FMRI of tactile, motor, and language tasks is feasible in patients with cerebral tumors. FMRI shows promise as a means of determining the risk of a postoperative motor deficit from surgical resection of frontal or parietal tumors.

Spinal epidural abscess: evaluation of factors influencing outcome.

Abstract: OBJECTIVE : The goal of this study was to critically evaluate the predictive efficacy of various clinical factors in spinal epidural abscess influencing outcome after surgical and/or medical treatment. METHODS : A retrospective analysis of 41 cases of spinal epidural abscess treated at Henry Ford Hospital between 1984 and 1992 was performed. RESULTS : Thirty patients underwent open surgery and received antibiotic therapy, and 11 patients received medical treatment alone. After a mean follow-up period of 20.9 months (range, 4-45 mo), 24 patients (58.5%) had no or minimal deficits, 9 patients (22%) had severe paresis or plegia and/or bowel/bladder dysfunction, and 8 patients (19.5%) died. Univariate analysis revealed patient age, degree of thecal sac compression, spinal location, surgical findings, and septic presentation to be significantly associated with outcome. In multiple logistic regression analysis, increasing age and degree of thecal sac compression were the only factors with significant independent association with poor outcome (P = 0.01 for both). A simple grading system (Grades 0-III) was developed, with patient age, degree of thecal sac compression, and duration of symptoms as the determining criteria. The incidence of poor outcome for patients with Grade 0 was 0%, compared to 85.7% for patients with Grade III. CONCLUSION : We conclude that long-term outcome after treatment of spinal epidural abscess can be predicted with the use of the proposed grading scheme. Surgical drainage plus parenterally administered antibiotics remains the recommended treatment, although medical treatment alone can also be used for certain patients.

Transcranial high-frequency repetitive electrical stimulation for recording myogenic motor evoked potentials with the patient under general anesthesia

Abstract: OBJECTIVE : To demonstrate the feasibility of transcranial high-frequency electrical stimulation with the patient under general anesthesia with propofol and alfentanil. This method may be a useful tool for intraoperative monitoring of the motor pathways during cerebral and spinal operations. METHODS : A short train from one to eight monopolar anodal electrical pulses was applied transcranially to the motor cortex with a frequency from 100 to 500 Hz in 10 patients. Myogenic motor evoked potentials (MEPs) were recorded from forearm flexor muscles, thenar, and hypothenar. Amplitude and latency of MEPs were evaluated after different stimulation parameters. This combination of anesthetic and transcranial stimulation technique allows recording of myogenic MEPs during general anesthesia, which was found not to be possible with single pulse transcranial stimulation. RESULTS : To elicit myogenic MEPs from the target muscles, stimulation had to be applied within the following parameters : minimum threshold intensity was 60 mA for forearm flexor and thenar and 80 mA for hypothenar ; minimum number of pulses was two for forearm flexor muscles and thenar and three for hypothenar ; minimum stimulation frequency was 200 Hz for thenar and hypothenar and 100 Hz for forearm flexor muscles. CONCLUSION : Transcranial high-frequency repetitive electrical stimulation seems to be a new method for monitoring the motor tract. With this method, it is possible to monitor the motor function without interfering with the surgical team or with the surgical treatment of infratentorial and spinal lesions. Monitoring of relaxation is necessary to compare the amplitude of MEPs.

Injuries involving the transverse atlantal ligament: classification and treatment guidelines based upon experience with 39 injuries.

Abstract: Comprehensive anatomic and clinical analyses of 39 patients with injuries involving the transverse atlantal ligament or its osseous insertions were performed to assess the morphology of the injured ligaments and the patients' capacity to heal. Injuries of the upper cervical spine were screened with plain radiographs, thin-section computed tomography, and magnetic resonance imaging studies. The injuries were classified as disruptions of the substance of the ligament (Type I injuries, n = 16) or as fractures and avulsions involving the tubercle for insertion of the transverse ligament on the C1 lateral mass (Type II injuries, n = 23). These two types of injuries had distinctly different clinical characteristics that were useful for determining treatment. Type I injuries were incapable of healing satisfactorily without internal fixation; they should be treated with early surgery. Type II injuries, which rendered the transverse ligament physiologically incompetent even though the ligament substance was not torn, should be treated initially with a rigid cervical orthosis, because they had a 74% success rate nonoperatively. Surgery should be reserved for patients with Type II injuries that have nonunion with persistent instability after 3 to 4 months of immobilization. Type II injuries had a 26% rate of failure of immobilization; therefore, close monitoring is needed to detect patients who will require delayed operative intervention.

Procedural and strain-related variables significantly affect outcome in a murine model of focal cerebral ischemia

Abstract: The recent availability of transgenic mice has led to a burgeoning number of reports describing the effects of specific gene products on the pathophysiology of stroke. Although focal cerebral ischemia models in rats have been well described, descriptions of a murine model of middle cerebral artery occlusion are scant and sources of potential experimental variability remain undefined. We hypothesized that slight technical modifications would produce widely discrepant results in a murine model of stroke and that controlling surgical and procedural conditions could lead to reproducible physiological and anatomic stroke outcomes. To test this hypothesis, we established a murine model that would permit either permanent or transient focal cerebral ischemia by intraluminal occlusion of the middle cerebral artery. This study provides a detailed description of the surgical technique and reveals important differences among strains commonly used in the production of transgenic mice. In addition to strain-related differences, infarct volume, neurological outcome, and cerebral blood flow appear to be importantly affected by temperature during the ischemic and postischemic periods, mouse size, and the size of the suture that obstructs the vascular lumen. When these variables were kept constant, there was remarkable uniformity of stroke outcome. These data emphasize the protective effects of hypothermia in stroke and might help to standardize techniques among different laboratories to provide a cohesive framework for evaluating the results of future studies in transgenic animals.