Background: The abducens nerve, cranial nerve VI (CNVI), is the medial-most nerve in the cavernous sinus. Its close proximity to the sphenoid sinus makes it susceptible to injury, invasion, or compression from a sphenoid pathology leading to horizontal gaze diplopia. A wide range of literature describes myriad causes for CNVI palsy, but there is a lack of references that point to paranasal sinus pathology as an etiology, as well as the prognosis and timeline for resolution. Here, we describe a series of patients that presented with CNVI palsy, their management, and prognosis for recovery. This study was designed to evaluate and understand prognostic factors predicting disease course and likelihood of resolution in patients with abducens nerve palsy.
Methods: A multi-institutional retrospective review was performed of all patients presenting with CNVI palsy between 2009 and 2012. The demographic data, radiological features, treatment regimens, and disease courses were analyzed.
Results: Fifteen patients at four institutions were identified. Seven patients had neoplasms originating from the paranasal sinuses, three suffered from allergic fungal sinusitis, three patients had invasive fungal sinusitis, one patient had fibrous skull base dysplasia, and one had chronic bacterial sinusitis. The average follow-up time from presentation was 9 months (range, 1-16 months). Thirteen patients underwent surgery, three received chemotherapy, and four had radiation therapy. CNVI palsy resolved in 50% of the cases, with an average time to resolution of 6 weeks (range, 2-12 weeks).
Conclusion: Paranasal sinus pathology is a rare cause of CNVI palsy. A number of factors may help to predict prognosis in these patients. Masses compressing, but not destroying or invading, the cavernous sinus had optimal posttreatment outcomes with full resolution occurring as early as 2 weeks. Destructive lesions that invaded CNVI and its vasculature, i.e., invasive fungus, were negative indicators for recovery. Knowledge of factors that affect recovery can help clinicians predict disease course and prognosis for resolution of the defect.