Cerebral hemodynamic compromise associated with limb shaking TIA and focal EEG slowing

We report four cases of cerebral hemodynamic compromise identified over a five year period. Cerebral hemodynamic compromise is characterized by reversible attacks of regional cerebral ischemia affecting patients with occlusive disease of main arteries supplying blood to the brain. All four of our patients had occlusion of one internal carotid artery (ICA) often associated with high grade stenosis or occlusion of the contralateral internal carotid artery and/or major intracranial arteries. All patients developed likely limb shaking transient ischemic attacks (TIAs) which occur during acute exacerbation of regional cerebral hypoperfusion. These events often trigger EEG testing because of suspicion of seizures. Each patient also had focal delta EEG slowing without evidence of noteworthy structural lesions on imaging scans. A discrepancy or mismatch between these testing results occurred. The patients' focal delta EEG slowing was attributed primarily to resting regional cerebral hypoperfusion. Diagnosis of cerebral hemodynamic compromise may be delayed when limb shaking TIA is misdiagnosed as a seizure disorder or when regional cerebral hypoperfusion is not considered as a potential cause of focal delta EEG slowing in older patients that have normal structural imaging studies. Our cases are discussed in light of the relevant EEG and clinical characteristics that have been described in reports of limb shaking TIA and structural imaging/focal delta EEG slowing mismatches.