Old Stroke as an Independent Risk Etiology for Todd's Paralysis

Todd's paralysis (TP) is a well-known postictal paresis in which patients present with transient weakness in their limb(s) after seizures. Although recognized as a stroke mimic in clinical practice, the pathophysiological mechanism and clinical features of TP remain unknown. Furthermore, its diagnosis can be erroneous in neurological emergency practice. We aimed to illustrate the clinical features and identify factors associated with TP.

This single-center, retrospective observational study included consecutive adult patients who presented with convulsive seizure and were referred to an urban tertiary care emergency department between August 2010 and April 2016. The diagnosis of TP was set as the primary outcome measure. Clinical and laboratory variables were evaluated.

Of 1381 eligible convulsive seizures in 1187 patients, TP was observed in 89 seizures (6.4%) in 75 patients. Patients with TP were significantly older, more likely to have convulsive status epilepticus, and had a longer duration of convulsion than patients without TP. TP was found in 19.7% (39 of 198) of convulsive seizures with remote etiologies including those due to old stroke. These etiologies were identified as independent significant risk factors for TP compared with seizures with cryptogenic etiology. The positive likelihood ratio of TP seizures was 11.2 for remote seizure etiologies.

Our results indicated that the diagnosis of TP highly suggests premorbid or comorbid structural lesions in the central nervous system, including old stroke. This consideration in seizure etiology may help in reducing the risk of misdiagnosis of acute stroke in emergency settings and further antiepileptic treatment.