Faculty Bibliography

Neurologists and emergency department physicians are frequently involved in the comprehensive evaluation of a first generalized seizure. An important aspect of this evaluation is a detailed history which can identify a provoked seizure secondary to drug toxicity and hence avoid unnecessary treatment with antiepileptic drugs. "Spice" is an umbrella term for a variety of synthetic cannabinoid products whose inhalation has been associated with an increasing number of toxic side effects resulting in emergency department visits. These side effects (including psychosis, tachyarrhythmia, and seizures) are not typically seen with marijuana (Cannabis sativa) use. We report 2 patients with no prior history of neurological disease that experienced their first generalized tonic-clonic seizure after smoking Spice. The mechanism behind the possible proconvulsant effect of synthetic cannabinoids is not known, but it may be due to their effects at the cannabinoid receptor CB1. Although the US Drug Enforcement Administration placed 5 synthetic cannabinoids into schedule 1 for a 12-month period beginning March 2011, new Spice products containing different synthetic cannabinoids continue to emerge. Because synthetic cannabinoids are not detectable on commercial drug screens it is important that neurologists and emergency department physicians consider Spice inhalation in their differential diagnosis of a first generalized seizure.

False lateralization of ictal onset by scalp EEG has been reported in patients with severe hippocampal sclerosis associated with hemispheric lesions or atrophy. There has been no report of cases of false lateralization by scalp EEG in patients without detectable structural abnormalities on MRI, or in patients with neocortical temporal lobe epilepsy. We report a case of false lateralization of ictal onset by scalp EEG in a patient with neocortical temporal lobe epilepsy and a normal MRI examination, investigated by intracranial EEG recordings. The ictal activity failed to propagate in the ipsilateral temporal lobe, but was strongly propagated to the contralateral temporal lobe resulting in a false lateralization of seizure onset by scalp EEG. It is possible that the poor homolateral propagation and evolution of ictal activity in this patient may be due to a functional rather than structural abnormality of the ipsilateral hippocampus, causing reduced synchrony and amplitude in the ipsilateral temporal cortex.

A case of atonic seizures localized to the frontal lobe by video-EEG monitoring is reported. The patient is a 38-year-old female with intractable atonic seizures characterized by abrupt onset of facial grimacing and a slow head drop. The onset of atonic seizures was about 6 years before presentation. Video-EEG monitoring showed that her atonic seizures were emanating from the right frontal head region. A high voltage spike and slow wave discharge invariably coincided with the onset of atonic seizures in the patient, similar to the interruption of tonic muscular activity time-locked to a spike on the EEG described in epileptic negative myoclonus; a syndrome associated with epileptic activity in the premotor cortex. Since routine MRI imaging in this patient was normal, diffusion tensor imaging (DTI) was applied to analyze the white matter integrity of the normal-appearing white matter in the frontal lobes of the patient. We compared the fractional anisotropy, parallel diffusivity and perpendicular diffusivity of normal-appearing white matter in the right versus left frontal lobe. Our results showed no significant difference between the two sides. Possible reasons for the normal DTI findings are discussed.

Synesthesia is experienced when sensory stimulation of one sensory modality elicits an involuntary sensation in another sensory modality. Auditory-visual synesthesia occurs when auditory stimuli elicit visual sensations. It has developmental, induced and acquired varieties. The acquired variety has been reported in association with deafferentation of the visual system as well as temporal lobe pathology with intact visual pathways. The induced variety has been reported in experimental and post-surgical blindfolding, as well as intake of hallucinogenic or psychedelics. Although in humans there is no known anatomical pathway connecting auditory areas to primary and/or early visual association areas, there is imaging and neurophysiologic evidence to the presence of early cross modal interactions between the auditory and visual sensory pathways. Synesthesia may be a window of opportunity to study these cross modal interactions. Here we review the existing literature in the acquired and induced auditory-visual synesthesias and discuss the possible neural mechanisms.

PURPOSE/OBJECTIVE:The dynamics of partial seizures originating from neocortical and mesial temporal regions are thought to differ, yet there are no quantitative comparative studies. The studies reported here investigate the duration of complex partial seizures in these populations using analyses of seizures recorded from intracranial arrays. METHODS:Data were collected from patients undergoing presurgical evaluation with intracranial electrodes. Seizure duration was defined as the time of earliest sustained ictal activity until the termination either in all electrodes (global duration, GD), or at the onset area (focal duration, FD). Patients were divided into three groups: mesial temporal lobe epilepsy (MTLE), neocortical temporal lobe epilepsy (NCTLE), and neocortical extratemporal lobe epilepsy (NCXTLE). RESULTS:Complex partial seizure durations were significantly longer in the MTLE group compared to the NCXTLE group. Median GD for MTLE was 106 s, and for NCXTLE was 78 s. There were no significant differences between seizure durations when comparing MTLE group to NCTLE group, or comparing NCTLE group to NCXTLE group. In the MTLE group, patients with bilateral recording arrays had significantly longer median seizure durations (GD and FD) than those sampled with unilateral arrays. CONCLUSIONS:In this select group of patients there is a significant difference between the duration of complex partial seizures of mesial temporal and neocortical extratemporal origin with mesial temporal complex partial seizures being longer. This may result from a number of possibilities including the bilateral propagation of some mesial temporal seizures and differences in ictal generators of the underlying networks.