Unilateral congenital third cranial nerve palsy with central nervous system anomalies: report of two cases.

The third nerve palsies are not uncommon in adults and are usually the result of vascular or compressive lesions. However, they are uncommon in children and are usually congenital. Congenital oculomotor nerve palsies were generally thought to exist in isolation without associated abnormalities; however, there have been conflicting reports in the literature as to the associations of congenital oculomotor palsies. In this report, we present 2 cases of congenital third cranial nerve palsy with neurological deficits and central nervous system abnormalities. The first patient had initial presentations of inequality in pupil size, exodeviation of the affected eye, and extreme hypotropia of the contralateral eye, which was also complicated by profound neurological deficits. Magnetic resonance imaging (MRI) scans disclosed hypoplasia of the right midbrain and corpus callosum. The second patient presented with an exodeviated right eye, and pupils non-reactive to light since birth. Computed tomography scans showed ventricular dilatation and absence of the septum pellucidum, which is compatible with septo-optic dysplasia (de Morsier syndrome). The clinical courses are presented, and we also review the literature concerning congenital third cranial nerve palsy associated with central nervous system anomalies.