Case Study

A 64 year old right-handed black male was seen for evaluation of spells. His past medical history included treatment for hypertension, diabetes mellitus, and hypercholesterolemia. Four generalized nocturnal seizures occurrred after a "TIA" though he was seizure free on phenytoin 300 mg nightly. However, he complained of feeling "sleepy and drunk". New daytime spells in the preceding 5 weeks were manifest as abrupt onset of slurred speech and "confusion" with left hand weakness for 1-2 minutes. During this time he would lie down during this time for fear of a convulsion. MRI demonstrated a small right parietal hyperintensity on DWI. EEG demonstrated right temporal delta. Carotid dopplers revealed a right ICA stenosis of >90% and an occlusion of the left ICA Intraoperative EEG was performed during carotid right endarterectomy.

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Figure: Intraoperative EEG monitoring demonstrating segments of EEG immediately before clamping (a) and 20 seconds following clamping of the right internal carotid artery (b). A longitudinal bipolar montage with a sensitivity 10 uv and filter settings of 1-70 Hz.

What caused these spells?

New or different "spells" should always prompt a differential diagnosis. Cerebral ischemia is the single most common cause of first seizures after 60 years of age1. TIAs may be confused with seizures though a "negative" motor deficit, positional recovery, and the ancillary testing suggest ischemia as opposed to focal seizures. Extended-release levitiracetam was substituted for phenytoin to avoid drug-drug interactions, and to avert adverse effects (above) that are common in this age group with enzyme-inducing AEDs.

Carotid endarterectomy was performed to prevent recurrent stroke with EEG used to detect the dynamic effects of ischemia. Unilateral or bilateral loss of fast frequencies may occur. Scalp EEG demonstrated bilateral suppression (B) in our patient though he recovered without incident and was maintained on anti-platelet therapy.

References

  1. Lossius MI, Ronning OM, Slapo GD, et al. Post-stroke epilepsy: occurrence and predictors –a long-term prospective controlled study (Akershus Stroke Study). Epilepsia 2005;46:248-262.
Authored By: 
William O. Tatum DO
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Authored Date: 
01/2011