Occasional convulsive seizures, non-convulsive seizures and the post-ictal state (the time after the visible seizure ends but the patient is still not back to normal) can have residual focal numbness or weakness that last minutes to hours or more after the event—unlike strokes these are not associated with demonstrable brain circulatory problems. This post-ictal phenomenon is referred to as a Todd’s Paralysis which can mimic strokes causing the patient to worry, “Am I having a stroke?” However, unlike most strokes, these worrisome symptoms soon dissipate. \
Transient ischemic attacks (TIAs) can cause these same symptoms. We use the term Todd’s Paralysis when the focal symptoms are due to seizures. TIAs are associated with brain circulation interruption and often predict a future stroke. These TIA symptoms can last minutes up to 24 hours and then disappear. But, if these focal symptoms occur and then disappear after a seizure we diagnose a “post-ictal phenomenon” or Todd’s Paralysis; this is not a stroke.
How do the patient and the doctor differentiate the post-ictal focal numbness/weakness symptoms associated with an epileptic seizure from a true brain circulatory interruption causing a TIA or a stroke? The bedside medical evaluation sometimes leads to uncertainty. Often, rapidly obtaining an electroencephalogram (EEG) to diagnose seizures is not possible. Then how do we make an accurate diagnosis? We obtain a brain CT or MRI scan.
Fortunately, the CT scan is readily available and easy to do in Western countries. The radiologist performs a CT scan and then can inject a dye-like substance into a vein. The brain CT picture is again examined for perfusion or circulatory changes highlighted by the dye; it can differentiate seizure from TIA/stroke in those patients with symptoms suggestive of stroke with focal numbness and/or weakness and/or speech problems. Loss of consciousness is usually not associated with stroke or TIA.
No focal increased flow or perfusion in the brain cortex is seen if it’s a post-ictal state affecting one side of the face/body called “lateralizing signs.” This is how doctors can make this crucial diagnosis and reassure the patient no stroke happened.
The younger the patient with post-ictal lateralizing focal symptoms/signs that is not in the typical older-adult stroke population, the more reassured everyone can be that a permanent stroke is not occurring. A past history of Todd’s Paralysis, especially in younger people with epilepsy is also reassuring against stroke.
Migraine sometimes occurs without headache and it is another condition that can mimic clinical presentation of TIA / stroke. Brain scans are usually normal in migraine, abnormal in stroke. And migraine is a repetitive clinical situation which makes differentiating Todd’s Paralysis from TIAs and Stroke, easier. Recurrent migraine usually occurs at younger ages than stroke, too.
Lance Fogan, M.D. is Clinical Professor of Neurology at the David Geffen School of Medicine at UCLA. “DINGS” is his first novel. It is a mother’s dramatic story that teaches epilepsy, now available in eBook, audiobook and soft cover editions.