Congenital Third Nerve Palsy
Third nerve palsies that are present at birth can be due either to a developmental abnormality or intrauterine/birth trauma. They represent nearly half of third-nerve palsies seen in children. Infants usually present with unilateral ptosis, some amount of ophthalmoplegia and pupil involvement (either dilated or miotic because of aberrant regeneration). The frequency of aberrant innervation seen in these cases suggests that the majority of the lesions occur along the peripheral nerve; however, central lesions have also been reported.
An uncommon association with congenital third nerve palsies is cyclic oculomotor paresis. Thought to be a form of aberrant innervation, cyclic third nerve palsies present as baseline oculomotor paresis with episodic third nerve activation resulting in miosis, elevation of the ptotic upper eyelid and adduction of the eye. These cycles can be debilitating as they often occur frequently and rhythmically. Noting this aberration prior to surgical planning is important, as correcting ptosis in such a patient will not change the cyclic changes of eyelid position (Biousse 2000).