Clinical and Radiologic Findings in Children with Anomalous Pontine Cranial Nerves.

Abstract

We retrospectively reviewed the clinical and radiologic findings in 17 children with an aberrant cisternal cranial nerve 7 (CN7), and found that these patients had additional anomalies involving other pontine cranial nerves (CNs). The hallmark imaging feature identified in all patients was an aberrant cisternal segment of an enlarged-appearing CN7. The abnormal nerve coursed anteriorly toward the Gasserian ganglion, where it fanned out toward the internal auditory canal, Meckel cave, or both. This finding was accompanied by a small cisternal CN5, which often had a lateral bowed appearance. CN5 and CN7 were abnormally close to each other. Meckel's cave appeared widened posteriorly and often was close to or merged with the internal auditory canal. Other abnormalities in the pontine CNs included CN8 deficiency in most children and variable CN6 deficiency. This constellation of findings was most often discovered in children having an MR evaluation for sensorineural hearing loss, and most patients had preserved facial nerve function. In patients with available genetic testing, no pathogenic variants were observed. Interestingly, in 13 children with an available birth history, 9 were notable for maternal or gestational diabetes (69%), suggesting a possible early intrauterine insult to the developing nerves.