Minor neurologic abnormalities were not recorded in patients who had severe neurologic abnormalities. Neurologic abnormalities documented after PEX began were distinct abnormalities. One patient had a recurrent minor abnormality after PEX began. Seven patients had distinct severe abnormalities both at presentation and after PEX began. Among the 4 categories of severe abnormalities, 17 of the 41 patients had abnormalities in multiple categories. One patient had an extension of her stroke after PEX began; 12 had seizures; 1 had seizures before PEX began and another seizure after her initial PEX; 31 had transient focal neurologic abnormalities; 5 had recurrent abnormalities (diplopia, aphasia, face/hand weakness/numbness) after PEX began; 19 had transient focal abnormalities as their only severe abnormality; and 12 had transient focal abnormalities in addition to seizures, stroke, and/or coma.