Symptomatic paroxysmal dysarthria-ataxia in demyelinating diseases.

Paroxysmal dysarthria-ataxia syndrome (PDA) is a rare neurological disorder that can be either primary or symptomatic of acute neurological dysfunction. Episodes of symptomatic PDA are poorly documented and there are no video reports. We describe the cases of two patients with symptomatic PDA related to demyelinating diseases. Detailed studies of the patients' speech disorders showed that the dysarthria and gait disorders were of the ataxic type in both cases. Both patients had midbrain lesions at or below the level of the red nucleus, confirming that this area is critically involved in PDA. The best clinical signs for distinguishing between symptomatic and primary PDA are adult onset and short (<1 min) episodes in the former. If these signs are present, brain MRI should be used to identify a cause of symptomatic PDA.