Amit M. Saindane

Real-time magnetic resonance-guided stereotactic laser amygdalohippocampotomy for mesial temporal lobe epilepsy.

BACKGROUND Open surgery effectively treats mesial temporal lobe epilepsy, but carries the risk of neurocognitive deficits, which may be reduced with minimally invasive alternatives. OBJECTIVE To describe technical and clinical outcomes of stereotactic laser amygdalohippocampotomy with real-time magnetic resonance thermal imaging guidance. METHODS With patients under general anesthesia and using standard stereotactic methods, 13 adult patients with intractable mesial temporal lobe epilepsy (with and without mesial temporal sclerosis [MTS]) prospectively underwent insertion of a saline-cooled fiberoptic laser applicator in amygdalohippocampal structures from an occipital trajectory. Computer-controlled laser ablation was performed during continuous magnetic resonance thermal imaging followed by confirmatory contrast-enhanced anatomic imaging and volumetric reconstruction. Clinical outcomes were determined from seizure diaries. RESULTS A mean 60% volume of the amygdalohippocampal complex was ablated in 13 patients (9 with MTS) undergoing 15 procedures. Median hospitalization was 1 day. With follow-up ranging from 5 to 26 months (median, 14 months), 77% (10/13) of patients achieved meaningful seizure reduction, of whom 54% (7/13) were free of disabling seizures. Of patients with preoperative MTS, 67% (6/9) achieved seizure freedom. All recurrences were observed before 6 months. Variances in ablation volume and length did not account for individual clinical outcomes. Although no complications of laser therapy itself were observed, 1 significant complication, a visual field defect, resulted from deviated insertion of a stereotactic aligning rod, which was corrected before ablation. CONCLUSION Real-time magnetic resonance-guided stereotactic laser amygdalohippocampotomy is a technically novel, safe, and effective alternative to open surgery. Further evaluation with larger cohorts over time is warranted.

Better object recognition and naming outcome with MRI-guided stereotactic laser amygdalohippocampotomy for temporal lobe epilepsy.

Patients with temporal lobe epilepsy (TLE) experience significant deficits in category‐related object recognition and naming following standard surgical approaches. These deficits may result from a decoupling of core processing modules (e.g., language, visual processing, and semantic memory), due to “collateral damage” to temporal regions outside the hippocampus following open surgical approaches. We predicted that stereotactic laser amygdalohippocampotomy (SLAH) would minimize such deficits because it preserves white matter pathways and neocortical regions that are critical for these cognitive processes.

Clinical course of idiopathic intracranial hypertension with transverse sinus stenosis

Objective: Transverse sinus stenosis (TSS) is common in idiopathic intracranial hypertension (IIH), but its effect on the course and outcome of IIH is unknown. We evaluated differences in TSS characteristics between patients with IIH with “good” vs “poor” clinical courses. Methods: All patients with IIH seen in our institution after September 2009 who underwent a high-quality standardized brain magnetic resonance venogram (MRV) were included. Patients were categorized as having a good or poor clinical course based on medical record review. The location and percent of each TSS were determined for each patient, and were correlated to the clinical outcome. Results: We included 51 patients. Forty-six patients had bilateral TSS. The median average percent stenosis was 56%. Seventy-one percent of patients had stenoses >50%. Thirty-five of the 51 patients (69%) had no final visual field loss. Eight patients (16%) had a clinical course classified as poor. There was no difference in the average percent stenosis between those with good clinical courses vs those with poor courses (62% vs 56%, p = 0.44). There was no difference in the percent stenosis based on the visual field grade (p = 0.38). CSF opening pressure was not associated with either location or degree of TSS. Conclusion: TSS is common, if not universal, among patients with IIH, and is almost always bilateral. There is no correlation between the degree of TSS and the clinical course, including visual field loss, among patients with IIH, suggesting that clinical features, not the degree of TSS, should be used to determine management in IIH.

Famous face identification in temporal lobe epilepsy: Support for a multimodal integration model of semantic memory

This study aims to demonstrate that the left and right anterior temporal lobes (ATLs) perform critical but unique roles in famous face identification, with damage to either leading to differing deficit patterns reflecting decreased access to lexical or semantic concepts but not their degradation. Famous face identification was studied in 22 presurgical and 14 postsurgical temporal lobe epilepsy (TLE) patients and 20 healthy comparison subjects using free recall and multiple choice (MC) paradigms. Right TLE patients exhibited presurgical deficits in famous face recognition, and postsurgical deficits in both famous face recognition and familiarity judgments. However, they did not exhibit any problems with naming before or after surgery. In contrast, left TLE patients demonstrated both pre- and postsurgical deficits in famous face naming but no significant deficits in recognition or familiarity. Double dissociations in performance between groups were alleviated by altering task demands. Postsurgical right TLE patients provided with MC options correctly identified greater than 70% of famous faces they initially rated as unfamiliar. Left TLE patients accurately chose the name for nearly all famous faces they recognized (based on their verbal description) but initially failed to name, although they tended to rapidly lose access to this name. We believe alterations in task demands activate alternative routes to semantic and lexical networks, demonstrating that unique pathways to such stored information exist, and suggesting a different role for each ATL in identifying visually presented famous faces. The right ATL appears to play a fundamental role in accessing semantic information from a visual route, with the left ATL serving to link semantic information to the language system to produce a specific name. These findings challenge several assumptions underlying amodal models of semantic memory, and provide support for the integrated multimodal theories of semantic memory and a distributed representation of concepts.

Brain Imaging in Idiopathic Intracranial Hypertension.

Background: The primary role of brain imaging in idiopathic intracranial hypertension (IIH) is to exclude other pathologies causing intracranial hypertension. However, subtle radiologic findings suggestive of IIH have emerged with modern neuroimaging. This review provides a detailed description of the imaging findings reported in IIH and discusses their possible roles in the pathophysiology and the diagnosis of IIH. Evidence Acquisition: References were identified by searches of PubMed from 1955 to January 2015, with the terms “idiopathic intracranial hypertension,” “pseudotumor cerebri,” “intracranial hypertension,” “benign intracranial hypertension,” “magnetic resonance imaging,” “magnetic resonance venography,” “computed tomography (CT),” “CT venography,” “imaging,” and “cerebrospinal fluid (CSF) leak.” Additional references were identified by hand search of relevant articles. When possible, we extracted the number of patients and control subjects from each study for each radiological finding. When at least 2 studies used the same criteria to define a radiological finding, all patients from these studies were pooled to obtain a mean sensitivity and specificity with 95% confidence interval. Results: Specific neuroimaging findings may suggest long-standing IIH, including empty sella, flattening of the posterior globes, optic nerve head protrusion, distention of the optic nerve sheaths, tortuosity of the optic nerve, cerebellar tonsillar herniation, meningoceles, CSF leaks, and transverse venous sinus stenosis. Conclusion: Although IIH remains a diagnosis of exclusion, the most recently proposed diagnostic criteria have included neuroimaging findings to suggest IIH when major diagnostic criteria are not fulfilled. However, these findings are not diagnostic of IIH, and their presence is not required for the diagnosis of definite IIH. Their incidental discovery on brain imaging should not prompt invasive procedures, unless other signs of IIH, such as papilledema, are present.

Incidence of cerebellar tonsillar ectopia in idiopathic intracranial hypertension: a mimic of the Chiari I malformation.

Some patients with intracranial hypertension may have nonrelated Chiari I malformations that are not responsive to surgical decompression. These authors set out to identify a subset of patients with IH who had tonsillar ectopia. They found that 21% of their patients with IH had cerebellar tonsillar ectopia that was often peglike and simulated true Chiari I malformations. An ancillary helpful finding was that in patients with IH and tonsillar ectopia the fourth ventricular obex was lower than in controls, implying that all posterior fossa structures are inferiorly displaced in this group of patients. BACKGROUND AND PURPOSE: IIH is a syndrome of elevated intracranial pressure without hydrocephalus, mass, or identifiable cause. Diagnosis is made by clinical presentation, intracranial pressure measurement, and supportive imaging findings. A subset of patients with IIH may have tonsillar ectopia, meeting the criteria for Chiari malformation type I but not responding to surgical decompression for Chiari I. The purpose of this study was to determine the incidence and morphology of cerebellar tonsillar ectopia in patients with IIH. MATERIALS AND METHODS: Forty-three patients with clinically confirmed IIH and 44 age-matched controls were included. Two neuroradiologists with CAQs reviewed sagittal T1-weighted MRI in a blinded fashion and measured cerebellar tonsil and obex positions relative to the foramen magnum and prepontine cistern width at the level of the midpons. RESULTS: Nine of 43 patients with IIH and 1/44 controls had cerebellar tonsillar ectopia of ≥5 mm. Five of 9 of patients with IIH with ectopia of ≥5 mm also had a “peglike” tonsil configuration. Patients with IIH had a significantly lower tonsillar position (2.1 ± 2.8 mm) than age-matched controls (0.7 ±1.9 mm, P < .05). The obex position was significantly lower in patients with IIH versus controls (−7.9 mm [above the FM] versus −9.4 mm [above the FM], P < .05). The prepontine width was not significantly different between the groups. CONCLUSIONS: Cerebellar tonsil position in patients with IIH was significantly lower than that in age-matched controls, often times peglike, mimicking Chiari I. A significantly lower obex position suggests an inferiorly displaced brain stem and cerebellum. When tonsillar ectopia of >5 mm is identified, imaging and clinical consideration of IIH are warranted to avoid misdiagnosis as Chiari I.

The brain connectome as a personalized biomarker of seizure outcomes after temporal lobectomy

Objective: We examined whether individual neuronal architecture obtained from the brain connectome can be used to estimate the surgical success of anterior temporal lobectomy (ATL) in patients with temporal lobe epilepsy (TLE). Methods: We retrospectively studied 35 consecutive patients with TLE who underwent ATL. The structural brain connectome was reconstructed from all patients using presurgical diffusion MRI. Network links in patients were standardized as Z scores based on connectomes reconstructed from healthy controls. The topography of abnormalities in linkwise elements of the connectome was assessed on subnetworks linking ipsilateral temporal with extratemporal regions. Predictive models were constructed based on the individual prevalence of linkwise Z scores >2 and based on presurgical clinical data. Results: Patients were more likely to achieve postsurgical seizure freedom if they exhibited fewer abnormalities within a subnetwork composed of the ipsilateral hippocampus, amygdala, thalamus, superior frontal region, lateral temporal gyri, insula, orbitofrontal cortex, cingulate, and lateral occipital gyrus. Seizure-free surgical outcome was predicted by neural architecture alone with 90% specificity (83% accuracy), and by neural architecture combined with clinical data with 94% specificity (88% accuracy). Conclusions: Individual variations in connectome topography, combined with presurgical clinical data, may be used as biomarkers to better estimate surgical outcomes in patients with TLE.

Asymmetric papilledema in idiopathic intracranial hypertension

Background: Very asymmetric papilledema in idiopathic intracranial hypertension (IIH) is rare, and few studies have dealt with this atypical presentation of IIH. Our aim was to describe the clinical and radiologic features of patients with IIH and very asymmetric papilledema. Methods: We identified all adult patients from our IIH database with very asymmetric papilledema defined as a ≥2 modified Frisén grade difference between the 2 eyes. Demographic data and initial symptoms were collected, and all brain imaging studies performed at our institution were reviewed. Results: Of the 559 adult patients with definite IIH, 20 (3.6%; 95% confidence interval [CI], 2.3–5.6) had very asymmetric papilledema at initial evaluation. They were older (39 vs 30 years; P < 0.001), had lower cerebrospinal opening pressure (35.5 vs 36 cm of water; P = 0.03), and were more likely to be asymptomatic compared with patients with symmetric papilledema (27% vs 3%; P < 0.001). Visual fields were worse on the side of the highest-grade papilledema (P = 0.02). The bony optic canal was smaller on the side of the lowest-grade edema in all 8 patients (100%) in whom the imaging was sufficient for reliable measurements (P = 0.008). Conclusions: IIH with very asymmetric papilledema is uncommon. Very asymmetric papilledema may result from differences in size of the bony optic canals, supporting the concept of compartmentation of the perioptic subarachnoid spaces.

Magnetic Resonance Thermometry-Guided Stereotactic Laser Ablation of Cavernous Malformations in Drug-Resistant Epilepsy: Imaging and Clinical Results.

BACKGROUND: Surgery is indicated for cerebral cavernous malformations (CCMs) that cause medically refractory epilepsy. Real-time magnetic resonance thermography (MRT)-guided stereotactic laser ablation (SLA) is a minimally invasive approach to treating focal brain lesions. SLA of CCM has not previously been described. OBJECTIVE: To describe MRT-guided SLA, a novel approach to treating CCM-related epilepsy, with respect to feasibility, safety, imaging, and seizure control in 5 consecutive patients. METHODS: Five patients with medically refractory epilepsy undergoing standard presurgical evaluation were found to have corresponding lesions fulfilling imaging characteristics of CCM and were prospectively enrolled. Each underwent stereotactic placement of a saline-cooled cannula containing an optical fiber to deliver 980-nm diode laser energy via twist drill craniostomy. MR anatomic imaging was used to evaluate targeting before ablation. MR imaging provided evaluation of targeting and near real-time feedback regarding the extent of tissue thermocoagulation. Patients maintained seizure diaries, and remote imaging (6-21 months postablation) was obtained in all patients. RESULTS: Imaging revealed no evidence of acute hemorrhage following fiber placement within presumed CCM. MRT during treatment and immediate postprocedure imaging confirmed the desired extent of ablation. We identified no adverse events or neurological deficits. Four of 5 (80%) patients achieved freedom from disabling seizures after SLA alone (Engel class 1 outcome), with follow-up ranging 12 to 28 months. Reimaging of all subjects (6-21 months) indicated lesion diminution with surrounding liquefactive necrosis, consistent with the surgical goal of extended lesionotomy. CONCLUSION: Minimally invasive MRT-guided SLA of epileptogenic CCM is a potentially safe and effective alternative to open resection. Additional experience and longer follow-up are needed. ABBREVIATIONS: CCM, cerebral cavernous malformations GRE, gradient recalled echo MRT, magnetic resonance thermography SLA, stereotactic laser ablation

Meningoceles in Idiopathic Intracranial Hypertension

OBJECTIVE MRI abnormalities have been described in patients with increased intracranial pressure (ICP), including in those with idiopathic intracranial hypertension (IIH). Spontaneous CSF-filled outpouchings of the dura (meningoceles) and secondary CSF leaks can occur from elevated ICP in patients with IIH; however, few studies have evaluated these findings. Our objective was to evaluate the frequency of spontaneous intracranial meningoceles among IIH patients and determine their association with visual outcome. MATERIALS AND METHODS We performed a retrospective case-control study of consecutive IIH patients between 2000 and 2011 who underwent MRI that included T2-weighted imaging. Demographics, presenting symptoms, CSF opening pressure, and visual outcome were collected for the first and last evaluations. Control subjects included patients without headache or visual complaints who had normal brain MRI results. Stratified analysis was used to control for potential confounding by age, sex, race, and body mass index. RESULTS We included 79 IIH patients and 76 control subjects. Meningoceles were found in 11% of IIH patients versus 0% of control subjects (p<0.003). Prominent Meckel caves without frank meningoceles were found in 9% of IIH patients versus 0% of control subjects (p<0.003). Among IIH patients, the presence of meningocele or prominent Meckel caves was not associated with demographics, symptoms, degree of papilledema, CSF opening pressure, visual acuity, or visual field defect severity. CONCLUSION Meningoceles are significantly more common in IIH patients than in control subjects and can be considered an additional imaging sign for IIH. Meningoceles are not, however, associated with decreased CSF opening pressure or better visual outcome in IIH.