Relative exophthalmos in facial nerve palsy

While ocular manifestations of facial nerve palsy, such as lagophthalmos are well known, there is limited knowledge on whether CN 7 palsy impacts globe positioning and its implications on symptoms and management. We hypothesize that CN 7 palsy is associated with ipsilateral exophthalmos.

A retrospective analysis of 500 patients diagnosed with facial nerve disorders, identified by ICD codes G51.0-G51.9, was conducted at a tertiary health care facility from January to November 2023. Patients were included if they had a diagnosis of unilateral facial nerve (CN 7) palsy and available computed tomography (CT) imaging after diagnosis. Patients under 18 years, those with bilateral CN 7 palsy, or with CT images of poor resolution were excluded. Axial position of the globe was measured on CT scans using 2 methods, both previously shown to correlate with Hertel exophthalmometry.

Of the 500 charts reviewed, 55 patients met inclusion criteria. 55% (n = 30) of patients were male, and 58% (n = 32) had right-sided CN 7 palsy. The predominant etiology was acute Bell's palsy 76% (n = 42). CT measurements revealed a statistically significant relative exophthalmos on the side affected by CN 7 palsy, measuring an average of 0.89 mm (Method 1) and 0.92 mm (Method 2) (both methods p < .001).

Our study is the first to highlight changes in ocular globe position in CN 7 palsies. The observed exophthalmos highlights the importance of assessing globe position in ophthalmologic management of the disorder.