Objective: There is only one neuropathologic report of congenital fibrosis of the extraocular muscles (CFEOM), and none of synergistic divergence. The aim of this report was to study the oculomotor nerve and the abducens nerve in 2 such patients with magnetic resonance imaging.
Design: Observational case reports.
Methods: Ophthalmologic examination and thin-sectioned magnetic resonance imaging across the brainstem level were performed in 2 patients with CFEOM and synergistic divergence. To confirm the accuracy of the procedure, we compared the results obtained with those of a control group of 40 individuals using the same technique.
Main outcome measures: The oculomotor nerve and the abducens nerve on magnetic resonance imaging.
Results: Magnetic resonance imaging disclosed bilateral hypoplasia of the oculomotor nerve in both patients, and absence of the abducens nerve on the affected side of synergistic divergence. The oculomotor and abducens nerves were observed in 80 of 80 eyes (100%) screened as controls.
Conclusions: In both patients with CFEOM and synergistic divergence, the oculomotor nerve was hypoplastic bilaterally, and the abducens nerve was absent on the side exhibiting synergistic divergence.