Neuropathological spectrum of drug resistant epilepsy: 15-years-experience from a tertiary care centre.

Neuropathology of drug resistant epilepsy (DRE) has direct bearing on the clinical outcome. Classification of the most common pathologies, hippocampal sclerosis (HS) and focal cortical dysplasia (FCD) have undergone several revisions and studies on the surgical pathology of DRE employing the updated ILAE classification are scarce. Here, we report the neuropathological spectrum of 482 surgically treated cases of DRE from a single institute using the latest ILAE classifications along with clinicoradiologic correlation. Majority of the cases (324, 67.2%) had temporal lobe epilepsy (TLE), with 158 (32.8%) having extratemporal seizure focus. Among TLE, HS was most common (n = 208, 64.2%), followed by neoplasms (42, 13%), FCD (26, 8%) and dual pathology (23, 7%). Less frequent were vascular malformations (cavernoma-3, arteriovenous malformation-1), mild malformation of cortical development (mMCD, 3), gliotic lesions (5), cysticercosis (2), double pathology (2) and polymicrogyria (1). Among extratemporal epilepsies, FCD was most common (46, 29.1%), followed by neoplasms (29, 18.3%), gliotic lesions (27, 17.1%), Rasmussen encephalitis (18, 11.4%), hypothalamic hamartoma (12, 7.6%), malformations of cortical development (10, 6.3%) and vascular malformations (6, 3.8%). Less frequent were double pathology (2, cysticercosis + FCD type IIb, DNET + FCD type IIb), mMCD (2), cysticercosis (1) and dual pathology (1). No underlying pathology was detected in 12 cases (2.5%). Radiopathological concordance was noted in 83%. In 36 cases (7.5%), histopathology detected an unsuspected second pathology that included FCD type III (n = 16) dual pathology (n = 18) and double pathology (n = 2). Further, in four MRI negative cases, histopathology was required for a conclusive diagnosis.

"Tailored" far lateral approach to anterior foramen magnum meningiomas - The importance of condylar preservation.

INTRODUCTION: Anterior and anterolaterally situated foramen magnum meningiomas are a technically complex subgroup of meningiomas. The need for an extensive exposure and bone work and their complex anatomy make them a difficult and challenging group of tumors to resect. The bone work has ranged from an extensive condylar resection to condylar preserving exposures. In this paper, we present our experience with condylar preserving or minimal condylar resection based approaches to these tumors. MATERIALS AND METHODS: All patients who underwent surgical resection of anterior and anterolaterally situated foramen magnum meningiomas were included in the analysis. The study period was more than 10 years from 2005 to 2015 at our institute; a tertiary referral centre in India. The records along with demographic profile, clinico-radiological features, surgical strategies, outcomes as well as mortality and morbidity were analysed. RESULTS: There were a total of 20 patients (9 males and 11 females) who were operated during the study period. The average age was 36.7 years. In 16 patients, gross-total or near-total resection could be achieved, four patients underwent subtotal resection. Eight patients had fresh morbidity in the form of new motor deficits, pseudomeningocele formation, worsening of the lower cranial nerve functions or post-operative adhesions leading to syrinx formation. The follow-up ranged from 6 months to 140 months. CONCLUSION: Foramen magnum meningiomas are an eminently treatable group of tumors. Condylar preservation provides a good visualization, while helping to preserve joint stability and in avoiding instrumental stabilization.

Microsurgical treatment of distal anterior cerebral artery aneurysms: A 25 year institutional experience.

INTRODUCTION: We present a retrospective study of distal anterior cerebral artery (DACA) aneurysms operated at our institute. MATERIAL AND METHODS: From 1988 to 2013, a total of 132 DACA aneurysms were managed surgically. The retrospective data of these patients was collected and analysed. RESULTS: They comprised 6.2% of all 2137 aneurysms operated during the same period. The mean age at presentation was 48.3 years (range: 24-77 years) and the male: female ratio was 1:2. The notable symptom in 114 (86.4%) patients was headache, in 94 (71.2%) was loss of consciousness, in 25 (18.9%) was seizures, and in 17 (12.9%) was limb weakness. There were 99 (75%) patients in World Federation of Neurosurgical Societies (WFNS) grade <3 at admission. On plain computed tomography (CT) scan, intracerebral hemorrhage was seen in 49 (37.1%) and intraventricular hemorrhage in 23 (17.4%) patients. The most common site of aneurysm was the pericallosal (A3 segment) artery noted in 65 (49.2%) patients. Multiple aneurysms were observed in 16 (12.1%) cases. The mean timing of surgery from the first ictus was 17.8 days. The delay was due to a late referral, poor general condition, recurrent bleeding, and worse WFNS grade at presentation. Aneurysms were operated through the following approaches: parasaggital craniotomy in 61 (46.2%), bifrontal craniotomy in 64 (48.5%), and frontotemporal craniotomy in 7 (5.3%). Aneurysms could be successfully clipped in 93.2% of the cases. Postoperative mortality was 8 (6%). The follow-up data was available for 83 (62.9%) patients. The mean duration of follow-up was 15.1 months (1-70 months), with more than 41 (31%) patients having a follow-up of more than 6 months. A favorable outcome (good recovery or moderate disability) was seen in 71 (85.5%) cases. CONCLUSIONS: A meticulous attention to the surgical technique provides gratifying results in DACA aneurysms even in patients who present initially in a compromised clinical status.

Intra-operative electrooculographic monitoring to prevent post-operative extraocular motor nerve dysfunction during skull base surgeries.

BACKGROUND AND AIMS: Intra-operative identification and preservation of extraocular motor nerves is one of the main goals of surgeries for skull base tumours and this is done by monitoring the extraocular movement (EOM). Intra-operative electromyographic monitoring has been reported, but it is a complex and skilful process. Electrooculography (EOG) is a simple and reliable technique for monitoring EOMs. We aimed to assess the utility of EOG monitoring in preventing extraocular motor nerve dysfunction during skull base surgeries. METHODS: In this retrospective cohort study, intra-operative EOG recordings were obtained using disposable needle electrodes placed on the periorbital skin and the polarity of the waves noted for interpretation. Triggered as well as continuous EOG responses were recorded after monopolar electrode stimulation of cranial nerve (CN) during tumour removal which helped the surgeon with careful dissection and avoiding potential nerve injuries. RESULTS: Of the 11 cases monitored, oculomotor and abducent nerves were identified in all cases, but the trochlear nerve could not be definitively identified. Six patients had no pre- or post-operative extraocular motor nerve dysfunction. The other five patients had pre-existing deficits before surgery, which recovered completely in two, significantly in one, and did not improve in two patients at 3-6 months follow-up. CONCLUSIONS: EOG was found to be a simple and reliable method of monitoring extraocular motor nerves (CNs III and VI) intraoperatively.

Pediatric awake craniotomy for seizure focus resection with dexmedetomidine sedation-a case report.

Resection of lesions near the eloquent cortex of brain necessitates awake craniotomy to reduce the risk of permanent neurologic deficits during surgery. There are limited reports of anesthetic management of awake craniotomy in pediatric patients. This report is on use of dexmedetomidine sedation for awake craniotomy in a 11-year-old child, without any airway adjuncts throughout the procedure. Dexmedetomidine infusion administered at a dosage of 0.2 to 0.7µg kg(-1) h(-1) provided adequate sedation for the entire procedure. There were no untoward incidents or any interference with electrocorticography, intraoperative stimulation, and functional mapping. Adequate preoperative visits and counseling of patient and parents regarding course and nature of events along with well-planned intraoperative management are of utmost importance in a pediatric age group for successful intraoperative awake craniotomy.

Clinical, electrophysiological, imaging, pathological and therapeutic observations among 18 patients with Rasmussen's encephalitis.

We studied the clinical, electrophysiological, imaging and pathological features of 18 patients with Rasmussen's encephalitis (RE). This descriptive study included 18 patients (six males, 12 females) with RE who were evaluated for demographic and phenotypic details, electroencephalogram (EEG) results, MRI results, pathological features, virological markers and outcome. Radiological staging as per Bien et al. and pathological staging in accordance with Robitaille et al. were performed. Simple partial seizures were the most common initial manifestation. During the disease course, epilepsia partialis continua (EPC) developed in 15/18 (83.3%) and hemiparesis in 17/18 (94.4%) patients. EEG revealed hemispheric slowing (100%), interictal epileptiform discharges (100%) and ictal pattern (44.4%). Brain MRI revealed unihemispheric focal cortical atrophy (100%), white matter changes (88.2%), basal ganglia-ipsilateral caudate and putamen involvement (50.0%) and progression of atrophy on serial MRI (100%). Unusual presentations in this series included late onset (n=1), and isolated lingual EPC (n=1). Diagnostic biopsies in two patients revealed Robitaille stage 3 disease. The six hemispherotomy specimens showed stage 2 disease in one, stage 3 in three and stage 4 in two cases. Heterogeneity in disease stage in the different neuroanatomical regions and within the same cortical segment reflected progression of immune-mediated damage. Immunomodulation provided only temporary benefit. Patients who underwent functional hemispherotomy had reduction in seizure frequency and improved quality of life. The clinical, EEG and MRI findings are in accordance with the established literature. MRI staging was concordant with Robitaille pathological staging. Immunomodulation did result in transient reduction in seizure frequency while surgery in six produced reasonable benefit.

Peculiarities and Patterns of Cervical Spine Injuries in Children and Adolescents: A Retrospective Series of 84 Patients from a Single Institute.

Cervical spine injuries occur infrequently in children but are associated with significant disability and mortality. A retrospective analysis was performed of 84 consecutive pediatric spine injuries treated at our institute from January 2002 to December 2011. The mean age was 14.7 years. There were 18 patients (21%) in group A (0-12 years) and 66 patients (79%) in group B (13-18 years). Overall, injury was more common in boys (ratio of 6:1). Trivial fall was the predominant cause in group A and fall from height in group B. There were 30 children (36%) with injuries of the upper cervical spine, 53 (63%) with injuries of the lower cervical spine and 1 patient (1%) with a combined injury of upper cervical spine and thoracic spine. Overall, 22% of the group A children and 67% of the group B patients had more severe injuries (Frankel grades A, B and C); 21% (18/84) were treated by surgical fusion. Where follow-up was available, 17 out of 22 children (77%) had good outcome (Frankel grade >C). In conclusion, mechanisms and patterns of injury in children are age related and the majority of the children had good outcome.

Rare complication of anterior communicating artery aneurysm coiling: Transient retrograde amnesia.

Amnesia is an unusual and rare complication following endovascular coiling of intracranial aneurysms. We present a case of anterior communicating artery (ACOM) aneurysm in which the patient developed retrograde amnesia following endovascular coiling of the aneurysm. On imaging there was infarct involving bilateral fornices. The patient showed significant clinical improvement on follow up.

Dexmedetomidine anesthesia enhances spike generation during intra-operative electrocorticography: A promising adjunct for epilepsy surgery.

BACKGROUND: Anesthetic-induced suppression of cortical electrical activity is a major concern during epilepsy surgery. Dexmedetomidine (Dex) has been recently evaluated in a few small series for its effect on the electrocorticographic spikes intra-operatively. METHODS: In this prospective study, electrocorticogram (ECoG) was monitored during dexmedetomidine infusion in 34 patients (M:F=23:11, age=29.2 ± 10.9 years; duration of epilepsy=15.3 ± 8.9 years) undergoing anterior temporal lobe resection with amygdalo-hippocampectomy for drug-resistant mesial temporal lobe epilepsy (Right: 18, Left: 16). Anesthesia was induced with thiopental/propofol and maintained with oxygen-N2O-isoflurane. ECoG was recorded for 5 min after the end tidal MAC of N2O and isoflurane were decreased to zero; anesthesia was maintained with O2:Air=50:50, vecuronium and fentanyl. ECoG was recorded using a 4-contact strip electrode for: (a) 5 min prior to dexmedetomidine (PreDEX), (b) 5 min during dexmedetomidine infusion (DEX; 1 µg/kg) and (c) 5 min after stopping dexmedetomidine (PostDEX). RESULTS: The ECoG spikes were manually counted in all the channels. The mean spike rate in the 2 channels with maximum spikes (MAX CH A and MAX CH B) was normalized to a 3-min duration. RM-ANOVA and post hoc comparison of three phases were used to compare the spike rates. The mean spike rate during Dex phase was higher compared to preDEX (MAX CH B: p=0.007 and MAX CH A: p=0.079) and PostDEX (MAX CH B: p=0.17, MAX CH A: p=0.79) phases. The spike rate increased in 67.6% patients, while 11.8% patients showed ≤ 25% reduction and 20.6% patients showed >25% reduction in spike frequency. CONCLUSION: Dexmedetomidine is useful during intra-operative ECoG recording in epilepsy surgery as it enhances or does not alter spike rate in most of the cases, without any major adverse effects.

Hemodynamic effects of dexmedetomidine during intra-operative electrocorticography for epilepsy surgery.

BACKGROUND: Dexmedetomidine, a predominant alpha-2-adrenergic agonist has been used in anesthetic practice to provide good sedation. The drug is being recently used in neuroanesthesia during awake surgery for brain tumors and in functional neurosurgery. MATERIALS AND METHODS: This prospective study analyzed the hemodynamic effects of dexmedetomidine infusion during electrocorticography in patients undergoing surgery for mesial temporal sclerosis. Dexmedetomidine infusion was administered during intra-operative electrocorticography recording, 15 minutes after the end tidal MAC of N2O and isoflurane were decreased to zero. Anesthesia was maintained with O2 : air mixture = 50:50, vecuronium and fentanyl. Heart rate (HR), mean arterial pressure (MAP) and end tidal carbon dioxide (ETCO2) were recorded across at induction, 2 min prior to dexmedetomidine (PreDEX), 5 min during dexmedetomidine infusion (DEX; 1 µg/kg), 5 min after stopping dexmedetomidine and 10 minutes after stopping dexmedetomidine. RESULTS: Forty patients with mesial temporal sclerosis (M: F = 27:13, mean age = 28.15 ± 10.9 years; duration of epilepsy = 12.0 ± 7.9 years) underwent anterior temporal lobe resection with amygdalohippocampectomy for drug-resistant epilepsy. Infusion of dexmedetomidine caused a transient fall in HR in 87.5% of patients and an increase in MAP in 62.5% of patients, which showed a tendency to revert back towards PreDEX values within 10 min after stopping the infusion. Sixty-five percent of the patients showed ≤25% reduction and 10% of them showed >25% reduction in HR. 47.5% of the patients showed ≤25% increase and 15% of them showed >25% increase in MAP. These changes were over a narrow range and within physiological limits. CONCLUSION: The infusion of dexmedetomidine for a short period causes reduction of HR and increase in MAP in patients, however the variations are within acceptable range.

Stereotactic biopsy of brainstem lesions: Techniques, efficacy, safety, and disease variation between adults and children: A single institutional series and review.

BACKGROUND: Stereotactic biopsy of brainstem lesions have been performed with varying indications, with most of the literature reporting on children. MATERIALS AND METHODS: The present study retrospectively analyzed all cases that underwent stereotactic biopsy for brainstem lesion in both adult and pediatric population between 1994 and 2009 in a single tertiary neurosurgical center. The clinical and radiological features, technique of the procedure, morbidity, diagnostic accuracy, spectrum of diagnosis, and variations in adult and pediatric population were analyzed. RESULTS: Eighty-two patients were included in the study. Computed tomography (CT) was used as guidance in 73 (38 children and 35 adults) patients and magnetic resonance imaging (MRI) in 9 (3 children and 6 adults). The biopsy was performed in a procedure room under local anesthesia in most adults, while children required sedation. Glioblastoma comprised 29.3% of all pathologies in children, compared with only 4.9% of the pathologies in adult population (P = 0.007). Tuberculosis was the next major diagnosis (9.8%). In 12 patients, initial biopsy was inconclusive. Following a repeat biopsy in 5 of these patients, a diagnosis was possible for 75/82 (91.5%) patients by STB. The location of the target, the choice of entry, the radiological characteristic of the lesion, enhancement pattern, and age group did not significantly correlate with the occurrence of inconclusive biopsy. Permanent complications occurred in two patients (2.4%). There was no mortality in this series. CONCLUSION: Stereotactic biopsy has an important role in brainstem lesions, more significantly in adults, due to wider pathological spectrum. It can be performed safely under local anesthesia through a twist drill craniostomy in most of the adults.

Clinico-pathological factors influencing surgical outcome in drug resistant epilepsy secondary to mesial temporal sclerosis.

BACKGROUND: Mesial temporal sclerosis (MTS) is the most common cause of drug resistant epilepsy amenable for surgical treatment and seizure control. METHODS: This study analyzed the outcome of patients with MTS following anterior temporal lobectomy and amygdalohippocampectomy (ATL-AH) over 10 years and correlated the electrophysiological and radiological factors with the post operative seizure outcome. RESULTS: Eighty seven patients were included in the study. Sixty seven (77.2%) patients had an Engel Class 1 outcome, 9 (11.4%) had Class 2 outcome. Engel's class 1 outcome was achieved in 89.9% at 1 year, while it reduced slightly to 81.9% at 2 years and 76.2% at 5 year follow up. Seventy seven (88.5%) patients had evidence of hippocampal sclerosis on histopathology. Dual pathology was observed in 19 of 77 specimens with hippocampal sclerosis, but did not influence the outcome. Factors associated with an unfavorable outcome included male gender (p=0.04), and a higher frequency of pre-operative seizures (p=0.005), whereas the presence of febrile seizures (p=0.048) and loss of hippocampal neurons in CA4 region on histopathology (p=0.040) were associated with favorable outcome. The effect of CA4 loss on outcome is probably influenced by neuronal loss in other subfields as well since isolated CA4 loss was rare. Abnormal post operative EEG at the end of 1 week was found to be a significant factor predicting unfavorable outcome (p=0.005). On multivariate analysis, the pre-operative seizure frequency was the only significant factor affecting outcome. CONCLUSIONS: The present study observed excellent seizure free outcome in a carefully selected cohort of patients with MTS with refractory epilepsy. The presence of dual pathology did not influence the outcome.

Central nervous system lymphoma: patterns of incidence in Indian population and effect of steroids on stereotactic biopsy yield.

BACKGROUND: Epidemiology of primary central nervous system lymphoma (PCNSL) world-wide shows an increase in incidence linked to human immunodeficiency virus (HIV) pandemic. MATERIALS AND METHODS: This retrospective review of case records analyzed the trends of hospital-based incidence of PCNSL over two decades (1991-2010), relation to immune status and effect of steroids on yield of stereotactic biopsy (STB). RESULTS: A total of 76 cases of PCNSL were diagnosed over a period of two decades. Incidence of lymphomas amongst all biopsied lesions showed a gradual increase from 0.18% at the beginning of study period to 0.41% at the end of study period. Only 8.6% (3 of 35 tested) of the PCNSL patients were positive for HIV. The mean age of patients with HIV infection (31.3 ± 3.5 years) was significantly lower compared with those without HIV infection (44.7 ± 10.9 years) (P = 0.033). Diagnosis was obtained by open biopsy in 32 patients (42.1%) and STB in 44 patients (57.9%). Open biopsy yielded a histological confirmation of PCNSL in all cases. Among those who underwent STB, the incidence of negative biopsy with short duration of steroids (≤ 1 week) was 33.3% and increased to 57.1% with increasing duration of steroid treatment (>1 week). CONCLUSIONS: This study documented an increase in hospital based incidence of PCNSL in our institute, independent of HIV association. Steroid intake administration for more than a week prior to biopsy adversely affected the yield of STB in PCNSL.

Evolution of MRI changes in Rasmussen's encephalitis.

PURPOSE: We studied the MRI findings in 16 patients with Rasmussen's encephalitis (RE), further analysed serial MRI changes in 11 of them and correlated it with clinical features. METHODOLOGY: The diagnosis of RE was based on the European consensus statement (Brain, 128, 2005, 454). Details related to demographical, clinical, MRI observations were analysed. RESULTS: Forty MRIs of brain of 16 patients were reviewed. Eleven patients had undergone serial brain MRIs ranging from two to five occasions. All the patients had unihemispheric focal cortical atrophy, predominantly in the perisylvian region (n = 13). Other features were white matter signal changes (n = 14), and ipsilateral caudate (n = 6) and putamen (n = 4) atrophy. Signal alterations in putamen and caudate were noted in four each. In all the 11 patients with serial MRI, there was progression of cerebral atrophy and a trend towards increase in MRI staging. The MRI signal changes remained same in five patients, resolved in three patients, differential change in two patients and increased in one patient. Diffusion-weighted imaging showed facilitated diffusion (n = 5), and MR spectroscopy showed reduced N-acetyl-aspartate and elevated lactate (n = 2). CONCLUSIONS: Pattern recognition of MRI findings and the changes in serial MRI might serve as a surrogate marker of disease viz. unihemispheric progressive focal cortical atrophy and signal changes predominantly in the perisylvian distribution and caudate followed by putamen involvement. This might assist in understanding and monitoring of the disease progression.

Expression pattern and prognostic significance of IGFBP isoforms in anaplastic astrocytoma.

The role of insulin-like growth factors and their regulatory proteins (IGFBP isoforms) in gliomas, particularly glioblastoma, has been a subject of active research in recent years. There is paucity of literature on their expression and impact on clinical outcome in anaplastic astrocytomas. To evaluate the expression patterns of IGFBP isoforms in anaplastic astrocytoma and correlate with clinical outcome, a retrospective study of 53 adult patients operated for supratentorial lobar anaplastic astrocytoma was performed. The protein expression of IGFBP isoforms (IGFBP-2, -3, -5 and -7), was studied by immunohistochemistry on all samples. The patients were followed up and outcome was documented. The median age at presentation in the present study was 35 years. The pattern of staining was intra cytoplasmic, homogenous and diffuse for IGFBP-2, -3 and -5 and granular for IGFBP-7. IGFBP-2 expression was significantly low in anaplastic astrocytoma as compared to other isoforms (P < 0.001). IGFBP-3 expression was higher than the other isoforms. However, its' expression correlated with favorable overall survival and demonstrated a trend towards significance on univariate analysis. The present study is the first of its kind to describe comprehensively the pattern of expression of IGFBP isoforms (IGFBP-2, -3, -5 and -7) in anaplastic astrocytomas. IGFBP-2 and IGFBP-3 expression patterns and correlation to prognosis were distinct in anaplastic astrocytoma patients, contradictory to what has been reported in glioblastoma, thus giving further evidence that anaplastic astrocytomas are molecularly distinct from glioblastoma.