Prevalence and significance of cranial nerve imaging abnormalities in patients with hereditary neuropathies: Clinical implications at the skull base

Abstract

Objective: To estimate the prevalence and significance of cranial nerve (CN) imaging abnormalities in patients with hereditary neuropathy and discuss clinical implications. Methods: We retrospectively analyzed data from patients at four tertiary academic medical centers with hereditary neuropathy diagnoses who had undergone gadolinium-enhanced magnetic resonance imaging (MRI) of the brain or skull base between 2004 and 2018. MRI scans, as well as computed tomography imaging when available, were reviewed and bivariable analysis was performed to identify predictors of CN abnormalities on imaging. Results: Among 39 patients meeting study criteria, 11 had clinical CN deficits (28%) and 8 had CN abnormalities on imaging (21%). Of the patients with CN abnormalities on imaging, half had CN deficits (4/8) and only a quarter had imaging abnormalities of the CNs with the deficits (2/8). Imaging abnormalities were found in varied CNs, including CNs III, V, VII, and the VII/VIII complex in the internal auditory canal. MRI obtained for the purpose of evaluating CN deficits had a statistically significant increased likelihood of containing CN imaging abnormalities. However, CN deficits themselves were not predictive of imaging abnormalities. Conclusion: Thickening and enhancement of CNs on MRI may be found in approximately 1/5 of patients with hereditary neuropathies and are inconsistently associated with clinical deficits. These imaging findings should not be mistaken for neoplastic and infectious processes as they may be manifestations of the patients' underlying genetic neuropathy. Level of Evidence: 4.