Fluctuating N IV paresis as presenting sign of a brain stem tumor: two pediatric cases

Isolated paresis of the trochlear nerve (N IV) is less frequent than paresis of other ocular motor nerves. It is most commonly due to head trauma and has only very rarely been described in association with brain tumors. Episodic N IV paresis has not been reported in children. We report on two pediatric patients developing N IV paresis at ages 5:10 y and 12:7 y. Both presented with diplopia and no other neurological symptoms. MRI showed signal changes affecting the tectum close to the inferior colliculus with low-grade astrocytomas being the most probable cause. Interestingly, during follow-up (26 and 16m, respectively) both patients showed recurrant episodes of diplopia with intermittent spontaneous improvement. Case 1 required ventriculo-cisternostomy for occlusive hydrocephalus at age 7:5 y while no changes of the initial lesion could be detected on MRI scans over time in case 2. Even in the presence of only transient N IV paresis, the possibility of an underlying space occupying lesions must be considered.

brain tumor - N IV paresis - diplopia