RESUMO
@#We report a rare case of a 45 year old female with 15 year history of progressive left facial thinning with frequent episodes of involuntary jaw closure and almost continuous rippling movements over her left sided masticatory muscles. There was localized scleroderma, left facial hemi atrophy and left hemi masticatory spasm. Localized scleroderma was proven histopathologically. Electrophysiological studies revealed normal blink reflex on both sides. Her masseter inhibitory reflex was absent bilaterally and surface electromyogram showed spontaneous bursts of high frequency activity over bilateral masseter and left temporalis muscles. The patient responded remarkably with bilateral botulinum toxin injection. This case highlights presence of rare bilateral involvement of HMS especially on EMG and excellent response to botulinum toxin.