Robert M. Worth

Temporal Lobe Epilepsy Surgery: Outcome, Complications, and Late Mortality Rate in 215 Patients

Summary:  Purpose: We studied the surgical outcome, complications, and the late mortality rate in a large group of patients with medically refractory temporal lobe epilepsy (TLE).

Longitudinal follow-up in 145 patients with medically refractory temporal lobe epilepsy treated surgically between 1984 and 1995

Summary: Purpose: There are few studies of prolonged longitudinal follow‐up after temporal resections.

Calcium requirement for axoplasmic transport in mammalian nerve.

TO account for fast axoplasmic transport, the movement of materials in nerve fibres, a model has been advanced in analogy to the sliding filament mechanism of muscle contraction1. We have shown in in vitro studies that transport is closely dependent on oxidative metabolism and a continual supply of ATP which could be hydrolysed by the Mg2+–Ca2+ ATPase present in nerve2. One might, therefore, expect a dependence of transport on either Ca2+ or Mg2+. But, in previous studies of axoplasmic transport in vitro, we and others found transport to continue as usual when nerves were placed in incubation media free of divalent cations3–5. Some support for the involvement of Ca2+ in transport was provided by the fact that a block of transport was found with 50 mM oxalate, presumably by a binding of intracellular Ca2+ (ref. 1) and the block of organelle movement observed in single fibres exposed to 10 mM EDTA6. We report here that clear evidence for a participation of Ca2+ in axoplasmic transport was revealed when a desheathed nerve preparation was used.

Temporal lobe epilepsy: analysis of patients with dual pathology

Objectives – To determine the frequency and types of dual pathology in patients with temporal lobe epilepsy (TLE) and to analyze the clinical manifestations and surgical outcome.

Temporal lobe epilepsy: analysis of failures and the role of reoperation.

Purpose – To analyze failures and reoperations in temporal lobe epilepsy (TLE), and compare these patients with those seizure‐free, and to determine any significant differences between the groups.

Comparative study of interictal PET and ictal SPECT in complex partial seizures

Objective – To compare the sensitivity of ictal 99mTc‐HMPAO single photon emission computed tomography (SPECT) with interictal 18F‐fluorodeoxyglucose positron emission tomography (PET) in localization of the epileptogenic focus in patients with medically intractable complex partial seizures (MI‐CPS). Material and methods – Retrospective analysis was performed on patients with MI‐CPS who underwent anterior temporal lobectomy from January 1993 onwards when PET became available to us for clinical studies at the Indiana University Medical Center. There were 38 female and 29 male patients (total=67) with MI‐CPS, 10 to 55.5 years of age (mean 31) and duration of their epilepsy from 1‐46 years (mean 21). Interictal PET was evaluated for evidence of focal hypometabolism and ictal SPECT for focal perfusion abnormality (hyperperfusion or hypoperfusion) by visual analysis. Results – Both Ictal SPECT and interictal FDG‐PET studies were obtained in 36 patients with MI‐CPS. PET showed definite hypometabolism in 30 and questionable hypometabolism in an additional two patients. Ictal SPECT correctly localized the seizure focus in 27 patients by demonstrating ictal hyperperfusion whereas in one the hyperperfusion was falsely localized. In an additional seven patients the ictal SPECT provided probable localization by demonstrating ictal hypoperfusion in the appropriate temporal lobe. The sensitivity of ictal SPECT and interictal PET was 34/36 and 32/36, respectively, the difference was not statistically significant (χ2y=0.18, DF=1, P=0.67). In six of the 36 patients the two tests were complementary to each other in providing localizing information. Conclusion – Ictal SPECT and interictal PET are equally sensitive and reliable techniques in localizing the epileptogenic focus in patients with MI‐CPS. They play a critical role in providing localization in MRI negative patients allowing surgical resection to be undertaken in many without additional invasive electrographic monitoring.

Saphenous nerve entrapment A cause of medial knee pain

Saphenous nerve entrapment is a seldom recognized cause of pain along the medial side of the knee and proximal calf. We are reporting our experience with 15 saphenous nerve entrapments in 14 patients between 1978 and 1981.

FDG-PET and MRI in temporal lobe epilepsy: Relationship to febrile seizures, hippocampal sclerosis and outcome

Objective– To correlate the volumetric head magnetic resonance imaging (MRI) and fluorodeoxyglucose‐positron emission tomography (FDG‐PET) scan findings with the history, intracarotid amobarbital procedure, pathology, and outcome in patients with medically refractory temporal lobe epilepsy. Material and methods– Thirty‐eight patients with temporal lobe epilepsy treated surgically following a comprehensive presurgical evaluation. Follow‐up ranged from 12 to 44 months. Results– Volumetric MRI showed ipsilateral hippocampal atrophy in 29 (76%), and PET scan showed ipsilateral temporal hypometabolism (PET‐TH) in 31 (81.5%) of patients. Eighty‐three percent of those patients with hippocampal sclerosis on MRI (MRI‐HS) had ipsilateral PET‐TH. Sixty‐six percent of patients with MRI‐HS had a history of prolonged febrile convulsions or a childhood febrile illness accompanied by convulsions, and 77% of patients with MRI‐HS had pathologically proven hippocampal sclerosis (HS). Ninety percent became seizure free or had rare seizures. Conclusion– FDG‐PET scans and head MRIs were complementary; 95% of patients had either MRI‐HS or temporal hypometabolism. MRI‐HS correlated with a history of febrile seizures and pathologically demonstrated hippocampal sclerosis. Ninety‐three percent of patients had focal functional deficits on the epileptogenic side. Concordance between PET temporal hypometabolism and MRI‐HS correlated with better outcome.

Brain stem auditory, visual and somatosensory evoked potentials in leukodystrophies.

Brain stem auditory (BAERs), visual (VEPs) and somatosensory evoked responses (SEPs) were recorded in 12 patients with Pelizaeus-Merzbacher leukodystrophy (PMD), three with adrenoleukodystrophy (ALD) and three with metachromatic leukodystrophy (MLD). All the 3 evoked responses were abnormal in all patients except normal VEPs and SEPs in a patient with early ALD. In most patients wave I with and without wave II were the only components of the BAERs that remained, subsequent components (waves III-VII) were absent. VEPs were severely altered; either no identifiable response to flash or pattern reversal stimuli could be recorded or the major components were significantly delayed in latency. Short latency SEPs following median nerve stimulation usually showed a normally recorded Erbs potential (N10), but an absence or marked attenuation of cervical (N14) and early scalp components (N19 and P22) or the occurrence of the scalp components with a significant delay. Multimodality evoked responses provide more information regarding the functional integrity of several afferent systems in patients with white matter disorders.

The design and hardware implementation of a low-power real-time seizure detection algorithm

Epilepsy affects more than 1% of the worlds population. Responsive neurostimulation is emerging as an alternative therapy for the 30% of the epileptic patient population that does not benefit from pharmacological treatment. Efficient seizure detection algorithms will enable closed-loop epilepsy prostheses by stimulating the epileptogenic focus within an early onset window. Critically, this is expected to reduce neuronal desensitization over time and lead to longer-term device efficacy. This work presents a novel event-based seizure detection algorithm along with a low-power digital circuit implementation. Hippocampal depth-electrode recordings from six kainate-treated rats are used to validate the algorithm and hardware performance in this preliminary study. The design process illustrates crucial trade-offs in translating mathematical models into hardware implementations and validates statistical optimizations made with empirical data analyses on results obtained using a real-time functioning hardware prototype. Using quantitatively predicted thresholds from the depth-electrode recordings, the auto-updating algorithm performs with an average sensitivity and selectivity of 95.3 +/- 0.02% and 88.9 +/- 0.01% (mean +/- SE(alpha = 0.05)), respectively, on untrained data with a detection delay of 8.5 s [5.97, 11.04] from electrographic onset. The hardware implementation is shown feasible using CMOS circuits consuming under 350 nW of power from a 250 mV supply voltage from simulations on the MIT 180 nm SOI process.