Moebius sequence: radiological approximations to molecular disturbances: an overview.

Moebius sequence is one of the rarest congenital cranial nerve abnormalities. Approximately 300 cases have been recorded in medical literature usually from single case report. Frequently characterized by either partial or complete agenesis of the VI and VII cranial nerves, Moebius sequence is also accompanied by vascular abnormalities and other alterations such as an aberrant or hypoplastic posterior fossa. We present 3 patients with Moebius sequence and their clinical and radiological features along with a discussion of their diagnostic approximations. The 3 patients (1 male and 2 females) with ages ranging from 24 days to 7 years in both outpatient and inpatient settings in a high complexity health center. Clinical and radiologic diagnosis with magnetic resonance imaging showed to be consistent with Moebius sequence. Moebius sequence initial diagnosis is based exclusively on nonunified clinical criteria, and there is an apparent genetic pattern of inheritance. Diagnostic clues include the child's inability for proper facial expressions, affectations in eye convergence, or diminished functional hearing. A radiological approach through the use of specific MRI sequences is often warranted in order to not only approximate cranial nerve abnormalities but also accompanying structural malformations.