MR imaging features of brain stem hypoplasia in familial horizontal gaze palsy and scoliosis.

We report the case of a child with horizontal gaze palsy, pendular nystagmus, and discrete thoracolumbar scoliosis. MR imaging of the brain depicted pons hypoplasia with an absence of the facial colliculi, hypoplasia, butterfly configuration of the medulla, and the presence of a deep midline pontine cleft (split pons sign). These MR imaging findings suggest familial horizontal gaze palsy with progressive kyphoscoliosis, a rare congenital disorder. To the best of our knowledge, MR imaging findings of only 4 similar cases, with or without progressive idiopathic scoliosis, have been reported. We discuss the pathogenesis substratum of this entity. Early recognition of this rare entity is important if supportive therapeutic measures in progressive scoliosis are to be applied.