The neuropathology of hereditary congenital facial palsy vs Mobius syndrome

Objective: To characterize the neuropathology of hereditary congenital facial palsy. Methods: The authors compared brainstem pathology of three members of one family with autosomal dominant congenital facial palsy to that in three age-matched controls. The neuropathologic findings of the familial patients were compared with those of patients with Mobius syndrome. Results: The authors observed a marked decrease in the number of neurons in the facial motor nucleus with corresponding small facial nerve remnants. In the patients with congenital facial palsy the number of facial motoneurons ranged between 280 and 1,680 as compared to 5,030 and 8,700 for controls. No signs of neuronal degeneration or necrosis with neuronal loss, gliosis, or calcifications were present. There were no other abnormalities of the rhombencephalon and its associated structures. The corticospinal tracts were fully developed. In contrast, Mobius syndrome is part of a more complex congenital anomaly of the posterior fossa with hypoplasia of the entire brainstem, including the traversing long tracts, with signs of neuronal degeneration and other congenital brain abnormalities. Conclusion: Neuropathologic findings confirm clinical observations that hereditary congenital facial palsy and Mobius syndrome are two different entities with a different pathogenesis.