Central respiratory dysfunction in Möbius syndrome

[Möbius syndrome and an apparently life-threatening event]

Möbius syndrome is characterized by congenital facial weakness with impairment of ocular abduction. A subgroup of these patients have associated apneas because of involvement of brainstem respiratory centers located slightly lateral to the abducens nuclei. We report a 7-month old infant admitted to the pediatric intensive care unit because of an episode of cyanosis, hypotonia and unresponsiveness. The patient then became respirator dependent afterwards. On examination, facial diplegia, impairment of ocular abduction and hypotonia were evident. Magnetic resonance imaging (MRI) revealed abnormal signal intensity in brainstem tegmentum. At the age of 11 months he was discharged but required a home ventilator. He died 5 months later due to an infection. Möbius syndrome is associated with central respiratory dysfunction. The finding of abnormal signal intensity in brainstem tegmentum on MRI is a possible predictor of apnea in these patients.

Möbius sequence: further in vivo support for the subclavian artery supply disruption sequence

Möbius sequence consists of a congenital bilateral facial nerve palsy and external ophthalmoplegia often associated with malformations of the limbs and orofacial structures. The pathogenesis of the sequence is a subject of debate. However, a new hypothesis proposes that Möbius sequence results from an interruption of embryonic blood supply (subclavian artery supply disruption sequence). Here we present an infant with bilateral facial nerve palsy (VII), external ophthalmoplegia (IV, VI), paresis of cranial nerves V, IX, X, XI, and XII, absence of the pectoralis major muscle (Poland anomaly), terminal transverse limb defects, and absence of the right diaphragm. Also, he was found to have discrete foci of brainstem calcifications in the region of the dorsal respiratory group on both CT scan and the histologic sections with microscopic evidence of diffuse brainstem "injury." The anomalies and histopathology noted in this infant imply that vascular insufficiency prior to the sixth week of gestation involving the proximal sixth intersegmental artery may result in the manifestations presented in this report and lend further support for the existence of a subclavian artery supply disruption sequence.

Möbius syndrome: evidence for a vascular etiology

We report five infants with restricted lateral gaze, facial diplegia, feeding difficulty, and/or respiratory disorders without significant pulmonary disease. Viral studies were negative in all patients. Two children had radiologic findings that included brain-stem hypoplasia and symmetric calcification in the dorsal tectum at the junction of the midbrain and pons. Autopsy of one of these two children demonstrated capillary telangiectasia in the mesencephalon and pons. The other three children had normal computed tomographic (CT) scans. However, their autopsies revealed focal brain-stem necrosis with calcifications but without vascular malformation. We suggest that the capillary malformations in one of our patients directly resulted in a vascular-induced necrosis and the manifestation of Möbius sequence. The similarity of symmetric neuropathologic findings in the three other patients and the CT scan in the one surviving patient suggest focal hemodynamic changes restricted to the posterior circulation, indirectly supporting a vascular theory of embryopathogenesis.