Susceptibility-weighted imaging in Todd paralysis.

A 10-year-old boy presented with left hemiplegia and facial droop after prolonged seizure activity overnight. MRI showed hypoperfusion involving the right cerebral hemisphere. Susceptibility-weighted imaging (SWI) demonstrated prominence of ipsilateral draining veins, indicating increased deoxyhemoglobin content within the hypoperfused territory (figure). There was no acute infarct. Weakness improved over several hours and the patient was discharged after returning to baseline. While the pathophysiology of Todd paralysis remains elusive, prior reports have documented reversible hypoperfusion. SWI is a robust and relatively novel imaging technique that is highly sensitive to deoxyhemoglobin and can be an adjunct in the evaluation of perfusion abnormalities.