Special Case
Horizontal gaze palsy with progressive scoliosis (HGPPS) is a very rare form of conjugate gaze palsy, appearing only in a few dozen families worldwide. HGPPS prevents horizontal movement of both eyes, causing people with this condition to have to move their head to see moving objects. In addition to the eye movement impairment, HGPPS is coupled with progressive scoliosis, although eye symptoms usually appear before scoliosis. HGPPS is caused by a mutation in the ROBO3 gene, which is important in cross-over of motor and sensory signals, preventing horizontal eye movement. In addition to the mutation, lesions in the midbrain and pons are common. This can also include a complete absence of a formation in the pons, the facial colliculus, which is responsible for some facial movements. The cause of progressive scoliosisin HGPPS and why HGPPS does not affect vertical gaze is unclear. Progressive scoliosis is normally treated with surgery.
Read more about this topic: Conjugate Gaze Palsy
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