Synergistic convergence and split pons in horizontal gaze palsy and progressive scoliosis in two sisters.

Synergistic convergence is an ocular motor anomaly where on attempted abduction or on attempted horizontal gaze, both the eyes converge. It has been related to peripheral causes such as congenital fibrosis of extraocular muscles (CFEOM), congenital cranial dysinnervation syndrome, ocular misinnervation or rarely central causes like horizontal gaze palsy with progressive scoliosis, brain stem dysplasia. We hereby report the occurrence of synergistic convergence in two sisters. Both of them also had kyphoscoliosis. Magnetic resonance imaging (MRI) brain and spine in both the patients showed signs of brain stem dysplasia (split pons sign) differing in degree (younger sister had more marked changes).