Congenital Cranial Dysinnervation Disorders: Facts and Perspectives to Understand Ocular Motility Disorders

Abstract

Congenital cranial dysinnervation disorders (CCDDs) are a group of neurodevelopmental diseases of the brainstem and the cranial nerves. Endogenic or exogenic disturbances lead to a primary dysinnervation of structures supplied by cranial nerves. Motility disturbances and potentially structural changes occur. Secondary dysinnervation occurs if fibers of other cranial nerves innervate the primarily misinner-vated structures. Synkinetic movements or cocontractions of antagonists result and may lead to structural changes in the muscles involved. Neurogenetic studies proved congenital fibrosis of the extraocular muscles (CFEOM), isolated and syndromic forms of Duane syndrome and horizontal gaze palsy with progressive scoliosis (HGPPS) to be related to mutations in genes that play a role in brainstem and cranial nerve development. By clinical features and theoretic considerations some forms of congenital ptosis, congenital fourth nerve palsy, Mobius syndrome and Marcus Gunn jaw winking phenomenon are understood as CCDDs. Other congenital disturbances of ocular motility with fibrotic features such as congenital Brown syndrome, congenital monocular elevation palsy and vertical retraction syndrome may be discussed as CCDDs.