Horizontal Gaze Palsy with Progressive Scoliosis and Characteristic MRI Appearance

Horizontal gaze palsy with progressive scoliosis (HGPPS) is an autosomal recessive disorder typically associated with scattered mutations of the ROBO3 gene. The gaze palsy is congenital and is often accompanied by horizontal pendular nystagmus; strabismushas also been reported. It has been described since 1970 in families descending from Europe, the Middle East, and Asia. MRI findings include hypoplastic basis pontis, pontine tegmentum, cerebellar peduncles, and abducens nuclei. Diffusion tensor imaging and evoked potentials demonstrate deficient hindbrain axonal crossing.