Spastic paretic hemifacial contracture in multiple sclerosis: a neglected clinical and EMG entity

Abstract

Background Spastic paretic hemifacial contracture (SPHC) is an uncommon condition, originally described as a sign of brainstem neoplasia, characterized by sustained unilateral contraction of the facial muscles associated with mild ipsilateral facial paresis. SPHC has only rarely been reported in the context of multiple sclerosis (MS). To further study and assess the frequency of SPHC in patients with MS. Methods We screened clinically 500 consecutive patients with MS for the presence of SPHC and further studied electrophysiologically any cases identified. Results We identified two patients who developed the condition during the course of an MS relapse. The estimated frequency of the condition was 0.4%. Both patients had relapsing–remitting MS. SPHC was characterized on Electromyography (EMG) by continuous resting activity of irregularly firing motor unit potentials, associated with impaired recruitment of motor units on voluntary contraction. Myokymic discharges were not present. Blink reflex studies were partly consistent with midpontine lesions in the vicinity of the facial nucleus ipsilateral to SPHC. MRI showed lesions in the ipsilateral dorsolateral midpontine tegmentum. Conclusions SPHC constitutes a rare but distinct clinical and EMG entity in patients with MS.