To look into symptomology, aetiology and pathophysiology of poststroke jaw opening oromandibular dystonia(OMD) and to discuss it in relation with a unique case.

 OMD, whether jaw opening-OMD(JO-OMD) or Jaw closing-OMD following stroke are rarely reported. We report a case of JO-OMD, developed immediately following acute right parieto-temporo-occipital infarction and reviewed the literature to analyse the possible pathophysiology.

A 50 year hypertensive lady presented with left sided weakness which was acute in onset  a year ago. Simultaneously she had inability to close her mouth due to continuous tightening of jaw because of which she was unable to speak. On examination she had JO-OMD with left sided hemiparesis and unique sensory trick (If she puts a piece of cloth in her mouth she could close without effort.). Brain MRI showed chronic right temporo-parieto-occipital infarction and a small left frontal gliotic lesion. FDG-PET  suggested severe hypometabolism in right parieto-temporo-occipital regions and left cerebellar hemisphere, suggestive of poststroke changes with crossed cerebellar diachisis. Also noted “relative” hypermetabolism in the left sensory-motor cortex and hypometabolism in left basal ganglia.

In literature, only three case of OMD following stroke have been reported. All with cerebellar stroke. This is the first case where patient has parieto-temporo-occipital infarction and there is temporal association of stroke with dystonia. Possible mechanism of OMD in this case appears to be due to “relative” hypermetabolism in the left sensory-motor cortex and hypometabolism in left basal ganglia following right sided stroke leading to functional mismatch between pathways responsible for dystonia.

This case provide a further evidence into possible cause of enigmatic pathophysiology of OMD. Though further research is required to confirm the exact mechanism of OMD but this case provides a new outlook into pathophysiology of the disease, different from the usual belief.