Oromandibular dystonia in encephalitis.

We report clinical and MRI findings of 17 patients with oromandibular dystonia (OMD) due to Japanese encephalitis (14) and nonspecific encephalitis (3). Their median age was 14(2-53) years and 9 were females. 8 patients had jaw open and 9 jaw close OMD. The severity ranged between 2 and 4 on a 0-4 scale, 11 patients were anarthric and needed tube feeding. Cranial MRI was abnormal in 13 patients; the abnormalities were in thalamus in 9, substantia nigra in 10, caudate in 3, globus pallidus and putamen in 2 each and pons in 1 patient. SPECT revealed hypoperfusion in thalamus in 4, basal ganglia in 1, frontal in 6, parietal in 3 and temporal in 1 patient. By 6 months, OMD regressed completely in 6, by 1 grade in 2 and remained unchanged in 7 patients. OMD in encephalitis is mainly due to JE and half of these patients improve.