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PubMed1990

[Experimental complex partial seizure and its possible clinical application].

Clinical applications of experimental models of complex partial seizure were studied using kainic acid-induced limbic seizures and amygdaloid kindling models. The following experiments were done aiming to study the basic approach for the treatment of the intractable complex partial seizures. 1) Degenerative focal lesions were made in bilateral substantia nigra and substantia innominata by a local microinjection of the ibotenic acid and influences upon limbic seizures were studied. Substantia innominata has a facilitatory effect upon secondary generalization of the limbic seizure while substantia nigra has an inhibitory influence. Degenerative lesions of the bilateral hippocampus inhibited development process as well as establishment of the kindling. 2) Resection of the primary epileptic focus in a limbic seizure status resulted in seizure control in cats with a single focus but not in another with multiple foci. 3) An autoradiography was done during limbic seizure status induced by kainic acid microinjection, and local cerebral glucose utilization (LCGU) and local cerebral blood flow were studied in order to study the relationship between cerebral metabolism and cerebral blood flow during limbic seizures. In the pyramidal cell of the hippocampus, an increased ratio of LCGU (x 4.1) is larger than that of LCBF (x 1.6). This uncoupling may be one reason of the neuronal cell damage during the limbic seizure status. 4) Autoradiography of the calcium suggested that one of the causes of hippocampal degeneration in intractable complex partial seizures should be a consequence of calcium influx into pyramidal cells during repeated limbic seizures.

Animals↗

PubMed2006

Brain surface reformatted imaging (BSRI) in surgical planning for resections around eloquent cortex.

BACKGROUND: Resective surgeries around eloquent areas challenge neurosurgeons and neuroimaging professionals due to difficulties to find anatomic references during surgery. Advances in magnetic resonance (MR) may prevent such deficits and provide information for accurate surgical planning. However, most of these techniques are expensive and not feasible in most centers. Using brain surface reformatted imaging (BSRI) of 3-D MR images, we sought to obtain data for surgical planning in patients with lesions around the motor cortex. METHODS: Thirteen patients with lesions around the eloquent areas and considered for resective surgery were evaluated. Patients had different ages with tumors and malformative lesions. They were scanned in a 1.5-T Siemens magnet with volumetric sequence after injection of Gadolinium. Postprocessing was done in an auxiliary console using MRI station software. We performed reformatting as described by Hattingen et al. [J Neurosurg 102:302-310, 2005] and used fixed skull and vascular structures as anatomical references. Distances to the reference points were measured to allow surgical planning and locate sites for cortical stimulation. Patients were also studied by blood-oxygen-level-dependent functional magnetic resonance imaging to locate the hand area before the surgical procedure. All patients had cortical stimulation during the resective procedure or chronic electrode stimulation before surgery. RESULTS: There was concordance between data from functional and structural data. In one case, partial resection was performed due to the high risk of severe deficits. Even in this case, there were clinical improvements and no additional deficits were observed. CONCLUSION: BSRI may be a useful tool for surgical planning around eloquent areas. It can reduce surgical time and morbidity and showed correlation with functional studies. Added to this is the low cost and feasibility in most centers that have standard MR scanners with Multiplanar Reformatting software.

Adolescent↗

PubMed2007

Age of seizure onset, functional reorganization, and neuropsychological outcome in temporal lobectomy.

Patients with early onset seizure disorder tend to have less cognitive decline following surgical resection than patients with late onset seizure disorder. Differential opportunity for presurgical cerebral functional reorganization has been proposed to account for this "age of onset" effect. However, the relationships between age of seizure onset, functional organization, and neuropsychological outcome remain incompletely understood. To shed additional light on these issues, we investigated 66 patients with anterior temporal lobectomies (37 left; 29 right), all of whom completed comprehensive neuropsychological assessment prior to and following surgical resection. The sample was divided into two groups: 34 patients with early onset (EO) epilepsy and 32 patients with late onset (LO) epilepsy. We found the typical age of onset effect: post-surgically, EO patients demonstrated relatively better outcome in multiple neuropsychological domains, especially verbal memory, compared to LO patients. Based on presurgical Wada testing, 23 patients were classified as having traditional cerebral functional organization (TFO) and 35 were classified as having nontraditional cerebral functional organization (NTFO). The NTFO group had an earlier age of seizure onset than the TFO group, and NTFO was more frequent in EO patients (70%) than LO patients (50%). NTFO patients demonstrated relatively better post-surgical outcome in several neuropsychological domains, compared to TFO patients. Our findings are consistent with the notion that functional reorganization may be an explanatory factor for the better neuropsychological outcome of EO epilepsy patients following anterior temporal lobectomy.

Adult↗

PubMed2004

Subcortical nodular heterotopia: a functional MRI and somatosensory evoked potentials study.

Subcortical nodular heterotopia (SNH) associated with refractory epilepsy may be surgically treated, and a positive outcome can be expected following the complete excision of the malformed tissue. Recent functional neuroimaging studies have suggested the possible functional relevance of cerebral malformations, and may make it possible to improve presurgical planning, thus allowing extended resections and minimising post-operative deficits. We here report the case of a 19-year-old man with epilepsy and a giant SNH associated with diffused abnormal gyrations of the right temporal-parietal regions. Cortical functional organisation was investigated by means of functional magnetic resonance imaging (MRI) during sensory and motor tasks, and somatosensory evoked potentials. The results revealed enlarged and displaced motor and sensory cortical areas with heterotopic tissue functional activation. The relevance of these findings is discussed in the light of the possible surgical treatment of drug-refractory epilepsy associated with cerebral malformations: surgical treatment based on conventional MRI studies alone, without taking the functional nature of dysplastic tissues into account, may lead to considerable side effects.

Adult↗

PubMed2003

VNS in patients with previous unsuccessful resective epilepsy surgery: antiepileptic and psychotropic effects.

OBJECTIVES: To assess the efficacy of vagus nerve stimulation (VNS) in patients with medically and surgically intractable complex partial seizures (CPS). PATIENTS AND METHODS: Sixteen patients with previous temporal [15] and frontal [one] resections were treated with VNS between 1994 and 1999 at King's College Hospital, London, UK. Post-operative video-electroencephalogram telemetry had shown that CPS started from the operated side in 12 patients, contralaterally in three and bilaterally independently in one. RESULTS: Three patients (18.75%) had 50% or more reduction in seizure frequency, but one showed severe worsening of epilepsy, which remitted upon VNS discontinuation. The antiepileptic effect of VNS was not different with respect to the type of operation (anterior temporal lobectomy vs amygdalohippocampectomy), the side of operation, or the side of seizure onset. We observed psychotropic effects in two patients with post-ictal psychosis, in two others with depression, and in a child with severe behavioral disorder. CONCLUSIONS: VNS may have a rather limited antiepileptic role to play in patients with persistent seizures following epilepsy surgery, but may independently possess useful antipsychotic and mood-stabilizing properties.

Adolescent↗

PubMed1995

Cortical stimulation mapping of phantom limb rolandic cortex. Case report.

Findings of intraoperative rolandic cortex mapping during awake craniotomy for a tumor in a patient with a contralateral upper-extremity amputation are presented. This patient sustained a traumatic amputation at the mid-humerus 24 years previously. Initially he had experienced rare painless phantom limb sensations but none in the past 10 years. Functional mapping during an awake craniotomy was performed to maximize safe tumor resection. Typical temporal and frontal speech areas were identified; motor representation of face and jaw extended more superiorly than sensory representation. Shoulder movements were evoked more laterally than usual at the superior aspect of the craniotomy. A small region of precentral gyrus, between the jaw and shoulder representations, elicited no detectable effect when stimulated. Somatosensory mapping showed a similar topographical distribution of face and mouth cortex; however, posterior and inferior to the shoulder motor cortex, right arm and hand (phantom) sensations were evoked. Evidence suggests that significant motor reorganization occurs following an amputation, with expansion of neighboring homuncular representations without loss of somatosensory representation, despite a long period of time without any sensation referable to the amputated limb. Contrary to models of sensory cortex plasticity, the plasticity of the adult cortex may be system specific, with reorganization present in motor, but not in sensory, cortical systems.

Amputation, Traumatic↗

PubMed2002

Distinctive pleomorphic xanthoastrocytoma-like tumor with exclusive abortive or aberrant neuronal differentiation and repeated recurrence--case report.

A 9-year-old girl with a 1-month history of generalized seizure presented with a distinctive tumor resembling pleomorphic xanthoastrocytoma. Neuroimagings showed a right frontotemporal lobe tumor. Histological examination of the resected tumor indicated similarity to pleomorphic xanthoastrocytoma without staining for glial fibrillary acidic protein. The neuronal immunoreactivity and ultrastructural features showed two discrepancies: Numerous cytoplasmic processes containing rich structures suspected to be microtubules and neurofilaments were present, but neurofilament protein 70 kd/200 kd staining was negative; and many tumor cells showed synaptophysin staining, but no synaptic structures or vesicles were observed. She suffered recurrence 14 months after the first surgery. The specimen from the second operation revealed no malignant transformation with a MIB-1 labeling index of 1.9%. Only 2 months after the second operation, there was a second recurrence. Irradiation was administered (60.2 Gy). Twenty-eight months later, no tumor progression was seen. This tumor was an unconventional type with "abortive" or "aberrant" neuronal differentiation or an extreme variant of pleomorphic xanthoastrocytoma.

Astrocytoma↗

PubMed2004

Optical imaging of epileptiform activity in human neocortex.

The surgical outcomes of patients suffering from neocortical epilepsy are not as successful as the surgical outcomes from resections of epilepsy patients with mesial temporal sclerosis. The main difficulty in the treatment of neocortical epilepsy is that current technology has limited accuracy in mapping neocortical epileptogenic tissue. It is known that the optical spectroscopic properties of brain tissue are correlated with changes in neuronal activity. The method of mapping these activity-evoked optical changes is known as imaging of intrinsic optical signals (IIOS). Activity-evoked optical changes measured in neocortex are generated by changes in cerebral hemodynamics (i.e., changes in blood oxygenation and blood volume). Our experimental approach was to acquire high-resolution IIOS maps of epileptiform activity in patients undergoing surgery for medically intractable neocortical epilepsy. Both spontaneous and stimulation-evoked epileptiform activity was monitored. Imaging of intrinsic optical signals was able to localize neocortical epileptic foci precisely by using changes in blood volume in contrast to changes in blood oxygenation. IIOS has the potential to translate from a purely research tool to a new intraoperative approach for the surgical treatment of neocortical epilepsy.

Blood Volume↗

PubMed2003

The multicenter study of epilepsy surgery: recruitment and selection for surgery.

PURPOSE: Multiple studies have examined predictors of seizure outcomes after epilepsy surgery. Most are single-center series with limited sample size. Little information is available about the selection process for surgery and, in particular, the proportion of patients who ultimately have surgery and the characteristics that identify those who do versus those who do not. Such information is necessary for providing the epidemiologic and clinical context in which epilepsy surgery is currently performed in the United States and in other developed countries. METHODS: An observational cohort of 565 surgical candidates was prospectively recruited from June 1996 through January 2001 at six Northeastern and one Midwestern surgical centers. Standardized eligibility criteria and protocol for presurgical evaluations were used at all seven sites. RESULTS: Three hundred ninety-six (70%) study subjects had resective surgery. Clinical factors such as a well-localized magnetic resonance imaging (MRI) abnormality and consistently localized EEG findings were most strongly associated with having surgery. Of those who underwent intracranial monitoring (189, 34%), 85% went on to have surgery. Race/ethnicity and marital status were marginally associated with having surgery. Age, education, and employment status were not. Demographic factors had little influence over the surgical decision. More than half of the patients had intractable epilepsy for >/=10 years and five or more drugs had failed by the time they initiated their surgical evaluation. During the recruitment period, eight new antiepileptic drugs were approved by the Food and Drug Administration for use in the United States and came into increasing use in this study's surgical candidates. Despite the increased availability of new therapeutic options, the proportion that had surgery each year did not fluctuate significantly from year to year. This suggests that, in this group of patients, the new drugs did not provide a substantial therapeutic benefit. CONCLUSIONS: Up to 30% of patients who undergo presurgical evaluations for resective epilepsy surgery ultimately do not have this form of surgery. This is a group whose needs are not currently met by available therapies and procedures. Lack of clear localizing evidence appears to be the main reason for not having surgery. To the extent that these data can address the question, they suggest that repeated attempts to control intractable epilepsy with new drugs will not result in sustained seizure control, and eligible patients will proceed to surgery eventually. This is consistent with recent arguments to consider surgery earlier rather than later in the course of epilepsy. Postsurgical follow-up of this group will permit a detailed analysis of presurgical factors that predict the best and worst seizure outcomes.

Adolescent↗

PubMedDate not supplied

Morphological patterns of seizures recorded intracranially.

We analyzed the frequency and morphological characteristics of the initial EEG manifestations of spontaneous seizures recorded from depth and subdural electrodes in 26 patients for whom pathological analysis of the area of seizure onset was available after resective surgery. Pathological features considered to be positive findings included well-defined structural lesions (hamartoma, neoplasm) or strictly defined mesial temporal sclerosis. Seizure onset was characterized by the frequency of the rhythmic discharge greater than 2 Hz in the first second and by the presence or absence of periodic low-frequency spikes (less than 2 Hz) preceding this stable change in background frequency. These features were correlated with the presence or absence of pathologic abnormalities in temporal and extratemporal locations. Although all patterns and frequencies of seizure onset were recorded in both medial temporal and extratemporal locations, medial temporal seizure onset was significantly more likely to have high frequency (greater than 13 Hz, p less than 0.00001) and tended to show periodic spikes prior to the seizure when it was associated with medial temporal sclerosis compared to when it was not. Extratemporal seizure onset associated with abnormal pathological substrate was significantly more likely to have a lower frequency (less than 13 Hz, p less than 0.05) and no periodic spikes before seizure onset (p less than 0.00001) than extratemporal seizure onset recorded from areas without pathological findings. Variability of seizure onset frequency was a characteristic of temporal, but not extratemporal, seizures (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Brain Diseases↗

PubMed2004

Convection-enhanced delivery of paclitaxel for the treatment of recurrent malignant glioma: a phase I/II clinical study.

OBJECT: A minority of patients with recurrent glioblastomas multiforme (GBMs) responds to systemic chemotherapy. The authors investigated the safety and efficacy of intratumoral convection-enhanced delivery (CED) of paclitaxel in patients harboring histologically confirmed recurrent GBMs and anaplastic astrocytomas. METHODS: Fifteen patients received a total of 20 cycles of intratumoral CED of paclitaxel. The patients were observed daily by performing diffusion-weighted (DW) magnetic resonance (MR) imaging to assess the convective process and routine diagnostic MR imaging to identify the tumor response. Effective convection was determined by the progression of the hyperintense signal within the tumor on DW MR images, which corresponded to a subsequent lytic tumor response displayed on conventional MR images. Of the 15 patients, five complete responses and six partial responses were observed, giving a response rate of 73%. The antitumor effect was confirmed by one biopsy and three en bloc resections of tumors, which showed a complete response, and by one tumor resection, which demonstrated a partial response. Lack of convection and a poor tumor response was associated with leakage of the convected drug into the subarachnoid space, ventricles, and cavities formed by previous resections, and was seen in tumors containing widespread necrosis. Complications included transient chemical meningitis in six patients, infectious complications in three patients, and transient neurological deterioration in four patients (presumably due to increased peritumoral edema). CONCLUSIONS: On the basis of our data we suggest that CED of paclitaxel in patients with recurrent malignant gliomas is associated with a high antitumor response rate, although it is associated with a significant incidence of treatment-associated complications. Diffusion-weighted MR images may be used to predict a response by demonstrating the extent of convection during treatment. Optimization of this therapeutic approach to enhance its efficacy and reduce its toxicity should be explored further.

Adult↗

PubMed1997

Outcome following surgery in patients with bitemporal interictal epileptiform patterns.

We reviewed outcome at least 1 year after temporal lobectomy in 44 patients with bitemporal, independent, interictal epileptiform patterns on EEG. All 44 underwent preoperative intracranial monitoring. Twenty-two (50%) were seizure-free, 14 (32%) had at a least 75% reduction in seizures, and eight (18%) had less than a 75% reduction in seizures. We analyzed age of seizure onset, duration of epilepsy, gender, side of operation, history and clinical findings, findings on MRI, results of intracranial EEG-video monitoring, presence or absence of lateralizing neuropsychological deficits, and pathology of resected tissue to identify factors associated with outcome. Three factors emerged as independently associated with a good outcome: concordance of MRI abnormality and side of operation (p = 0.01), history of febrile seizures (p = 0.04), and 100% lateralization of intracranially recorded ictal onsets to the side of operation (p = 0.05). A seizure-free outcome was much more likely to occur if more than one of these factors was present: with at least two factors co-existing, 83% (15/18) of patients were seizure-free, while only 35% (7/20) were seizure-free with a single factor present (p = 0.0009). Of the six patients without any of the three factors, none were seizure-free. We conclude that it is possible to predict reasonably which patients with bitemporal epileptiform abnormalities will have a good outcome after surgery.

Adolescent↗

PubMed2002

Future aspects of epilepsy research.

This contribution in honour of Prof. Gerhard Pendl first reviews some recent studies on resected tissue, migrational disorders, and Rasmussen's Syndrome. These areas of basic research profit from recent advances of molecular biology and genetics. On the clinical side, some studies dealing with proton magnetic resonance spectroscopy are reviewed. In order to highlight the progress in clinical epilepsy research using modern methods of structural and functional imaging, functional outcome prediction is also reviewed. This kind of advanced clinical research is dealt with by discussing risk factor assessment associated with postsurgical decrements in memory. With regard to motor functions, we compare the yield of functional MR and intraoperative cortical stimulation in patients with lesions in or close to the Rolandic cortex. Progress in the field of advanced EEG analysis is reviewed in the context of "seizure prediction" and cognitive event-related potentials. Finally some of the new epilepsy treatment options, such as Gamma Knife treatment, where Prof. Pendl's group made pioneering contributions, are dealt with.

Animals↗

PubMed2002

Metastatic papillary craniopharyngioma: case study and study of tumor angiogenesis.

We report a case of suprasellar papillary craniopharyngioma metastatic to the temporoparietal region 2 years after its initial resection. The literature documents examples of craniopharyngioma recurrences along the surgical tract, as well as remote ipsi- and contralateral metastases via cerebrospinal fluid seeding. Ours is the second report of a craniopharyngioma of papillary type to exhibit metastatic behavior. The tumor spread opposite the side of craniotomy. Although a rare occurrence, it confirms the limited capacity of histologically benign craniopharyngiomas to undergo meningeal seeding, likely the result of surgical manipulation. Immunohistochemical demonstration of increased microvascular density and vascular endothelial growth factor expression, as well as a high vascular endothelial growth receptor (VEGFR2) signal by in situ hybridization, suggests that tumor vascularity facilitated angiogenesis and may have been involved in the establishment and growth of the metastatic deposit.

Biopsy↗

PubMed2006

Ictal SPECT in neocortical epilepsies: clinical usefulness and factors affecting the pattern of hyperperfusion.

INTRODUCTION: The aims of this analysis were to: (1) determine the value of ictal SPECT in the localization of neocortical epileptogenic foci, (2) evaluate the relationships between the results of ictal SPECT and other potential affecting factors, and (3) compare traditional visual analysis and the subtraction method. METHODS: We retrospectively analyzed 81 consecutive patients with neocortical epilepsy who underwent epilepsy surgery and achieved a favourable surgical outcome, including 36 patients with normal MRI. Side-by-side visual analysis and subtraction images were classified as correctly localizing,correctly lateralizing, or non-localizing/non-lateralizing images according to the resected lobe. RESULTS: Side-by-side visual analysis and subtraction SPECT correctly localized the epileptogenic lobe in 58.9% and 63.0% of patients, respectively. The two methods were complementary and the diagnostic sensitivity of ictal SPECT using the two methods was 79.0%. Ictal SPECT using the visual method correctly localized the epileptogenic lobe more frequently in patients with a localizing pattern of ictal scalp EEG at the time of radioligand injection. When using subtraction images, an injection delay of less than 20 s after seizure onset was significantly correlated with correct localization. The subtraction method was superior to the visual method for localizing frontal lobe epilepsy (FLE) and parietal lobe epilepsy (PLE), and in patients with non-localizing/non-lateralizing EEG at onset. CONCLUSIONS: Ictal SPECT analyses using visual and subtraction methods are useful and complementary for the localization of the epileptogenic foci of neocortical epilepsy. Early radioligand injection and ictal EEG patterns are related to ictal SPECT localization. The subtraction method may be more useful in some epileptic syndromes.

Adolescent↗

PubMed1998

Physiological analysis of Rasmussen's encephalitis: patch clamp recordings of altered inhibitory neurotransmitter function in resected frontal cortical tissue.

Rasmussen's encephalitis (RE) is a progressive, rare childhood disease characterized by severe epilepsy, hemiplegia, dementia, and inflammation of the brain. While one mechanism underlying the pathogenesis of RE has been hypothesized to be mediated by production of excitotoxic GluR3 autoantibodies to the AMPA receptor, other neuropathological etiologies have also been indicated. Whole-cell patch clamp recordings of GABA(A) receptor mediated responses were conducted in neurons acutely isolated from an RE patient, and compared to properties of non-focal human temporal cortical neurons. RE neurons appeared similar anatomically to control cortical neurons. Significant differences in GABAergic responses were evident between RE and control neurons. GABA was significantly more potent in RE than in control cortical neurons (EC50 of 13 microM vs 23 microM, respectively). In addition, the overall efficacy of GABA was significantly decreased in RE neurons, associated with a decrease in postsynaptic GABA current density in RE neurons (5.1 pA/microm2) in comparison to controls (9.2 pA/microm2). Augmentation of GABA responses by the benzodiazepine, clonazepam (CNZ), was significantly reduced in RE in comparison to control neurons (34% vs 99% augmentation at 100 nM). The RE-associated reduced functional efficacy and altered pharmacology of neuronal GABA(A) receptors is consistent with overall disinhibition in RE neurons, and could contribute to the generation of the severe epileptic activity evident in this disorder.

Cell Size↗

PubMedDate not supplied

[Complications during epilepsy surgery. Experience after 102 interventions between 1997 and 2001].

OBJECTIVES: To describe perioperative complications in different approaches to surgery for epilepsy. PATIENTS AND METHODS: All patients undergoing surgery related to epilepsy between January 1997 and December 2001 were studied. We gathered information on patient characteristics, diagnosis, anticonvulsant treatment, surgical procedure, type of anesthesia and perioperative complications. RESULTS: Ninety-eighty patients underwent 90 procedures under general anesthesia and 12 procedures with local anesthesia and sedation. Surgery was for anteromedial temporal resection in 74 patients, electrode implantation through the foramen ovale in 10 patients, extratemporal excisions in 7 patients, callosotomy in 3 patients, functional hemispherectomy in 3 patients, implantation of electrode grids in 2 patients, and craniotomy with an awake patient in 3 cases. Complications related to the surgical procedure were intraoperative bradycardia (5 cases), dural tension at the start of surgery (3), bleeding (2) and seizure (1). Complications related to anesthesia were bronchospasm (2 cases), histamine-releasing reaction upon administration of the muscle relaxant (1), and difficult intubation (1). During recovery we saw 1 case of postoperative aphasia, 1 of polyuria, 1 of pulmonary condensation, and 1 of factor VII deficit requiring plasma transfusion. CONCLUSIONS: The rate of perioperative complications in surgery for drug-resistant epilepsy is low, the most common complication being self-limiting bradycardia related to surgical maneuvers.

Adult↗

PubMed2006

Custom-tailored transdural anterior transpetrosal approach to ventral pons and retroclival regions.

OBJECT: The extradural anterior petrosectomy approach to the pons and midbasilar artery (mid-BA) has the main disadvantage that the extent of resection of the petrous apex cannot be as minimal as desired given that the surgical target field is not visible during bone removal. Unnecessary or excessive drilling poses the risk of injury to the internal carotid artery, vestibulocochlear organ, and seventh and eighth cranial nerves. The use of a custom-tailored transdural anterior transpetrosal approach can potentially avoid these pitfalls. METHODS: A technique for a transdural anterior petrosectomy was developed in the operating theater and anatomy laboratory. Following a subtemporal craniotomy and basal opening of the dura mater, the vein of Labbé is first identified and protected. Cerebrospinal fluid ([CSF] 50-100 ml) is drained via a spinal catheter. The tent is incised behind the entrance of the trochlear nerve toward the superior petrosal sinus (SPS), which is coagulated and divided. The dura is stripped from the petrous pyramid. Drilling starts at the petrous ridge and proceeds laterally and ventrally. The trigeminal nerve is unroofed. The internal acoustic meatus is identified and drilling is continued laterally as needed. The bone of the Kawase triangle toward the clivus can be removed down to the inferior petrosal sinus if necessary. Anterior exposure can be extended to the carotid artery if required. It is only exceptionally necessary to follow the greater superior petrosal nerve toward the geniculate ganglion and to expose the length of the internal acoustic canal. The modified transdural anterior petrosectomy exposure has been used in nine patients-two with a mid-BA aneurysm, two with a dural arteriovenous fistula, one with a pontine glioma, three with a pontine cavernoma, and one with a pontine abscess. In one patient with a mid-BA aneurysm, subcutaneous CSF collection occurred during the postoperative period. No CSF fistula or approach-related cranial nerve deficit developed in any of these patients. There was no retraction injury or venous congestion of the temporal lobe nor any venous congestion due to the obliteration of the SPS or the petrosal vein. CONCLUSIONS: The custom-made transdural anterior petrosectomy appears to be a feasible alternative to the formal extradural approach.

Brain Stem Neoplasms↗