Todd's phenomenon

Todd's paresis
Classification and external resources
Specialty	neurology
ICD-10	G83.8
ICD-9-CM	344.89
MeSH	D010243
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Todd's paresis, Todd's paralysis, or Todd's palsy (or postictal paresis/paralysis, "after seizure") is focal weakness in a part of the body after a seizure. This weakness typically affects appendages and is localized to either the left or right side of the body. It usually subsides completely within 48 hours. Todd's paresis may also affect speech, eye position (gaze), or vision.

The condition is named after Robert Bentley Todd (1809–1860), an Irish-born London physiologist who first described the phenomenon in 1849. It may occur in up to 13% of seizure cases. It is most common after a focal motor seizure affecting one limb or one side of the body. The generally postulated cause is the exhaustion of the primary motor cortex, although no conclusive evidence is available to support this.

The classic presentation of Todd's paresis is a transient weakness of a hand, arm, or leg after focal seizure activity within that limb. The weakness may range in severity from mild to complete paralysis.

When seizures affect areas other than the motor cortex, other transient neurological deficits can take place. These include sensory changes if the sensory cortex is involved by the seizure, visual field defects if the occipital lobe is involved, and aphasia if speech, comprehension or conducting fibers are involved.

Postictal paresis (PP), although familiar to neurologists, has not been well-studied. One retrospective observational study evaluated 328 selected patients from ages 16 to 57 years who had prolonged video-electroencephalogram (EEG) monitoring for medically intractable epilepsy and focal seizure onset; those with nonepileptic seizures, status epilepticus, and Lennox-Gastaut syndrome were excluded. The following observations were made:

Of all seizures followed by PP, the following features were noted:

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