Central Nervous System- Basic Neuropathology

Question No. 22. The Answer is: (E)- All of the above are true.

Discussion: Möbius syndrome is a disorder characterized by lifetime facial paralysis and internal strabismus due to the absence or underdevelopment of two important nerves - the sixth (abducens) and seventh (facial) cranial nerves. There is occasional involvement of other cranial nerves, especially the lower cranial pairs. Möbius syndrome has been used to describe a variety of heterogenous syndrome with features of 6th and 7th cranial nerve palsy. The term Möbius syndrome should only be used in patients with bilateral 6th and 7th cranial nerve palsy that the patient is fully conscious, have no central respiratory depression, and in whom limb or muscle defects are absent or minimal. Möbius syndrome is associated with a 10% incidence of mental retardation. Other clinical features have recently been described in association with Mobius syndrome, including upper labial deficiency, cataplexy, and poor impulse control with exhibitionism and aggression. The etiology of Möbius syndrome is unknown. In most cases it probably is the result of a focal destructive lesion in the brain stem that may be resulted from hypoxic-ischemic, hemorrhagic or even thromboembolic. The combined presentation of 6th and 7th nerve palsy may be resulted from the close location of these two cranial nerve nuclei as the efferent tracts of the 7th nerve wrap around the abducen nuclei.

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