Cranial Base Manifestations of Granulomatosis with Polyangiitis

Objective: Although granulomatosis with polyangiitis (GPA; Wegener’s granulomatosis) is classically characterized by systemic disease involving the kidneys and airway, approximately 10% of patients who have it present with isolated central nervous system disease. When involving the skull base, GPA frequently mimics more common pathology, resulting in diagnostic challenges and delay. The primary objective of this study is to characterize the cranial base manifestations of GPA, highlighting aspects most relevant to the skull base surgeon. Study Design: Retrospective review. Setting: Tertiary academic referral center. Subjects and Methods: Retrospective analysis of all patients with skull base GPA treated at a tertiary referral center from January 1, 1996, to May 1, 2018. Results: Twenty-nine patients met inclusion criteria. Twenty-one (72%) initially presented with skull base symptomatology as their cardinal manifestation of GPA. Twenty-four (82%) presented with cranial neuropathy at some point in their disease course. The trigeminal nerve was most commonly involved (12 of 24, 50%), followed by the facial (11 of 24, 46%) and optic (8 of 24, 33%) nerves. Eighteen patients reported hearing loss attributed to the GPA disease process, presenting as conductive, sensorineural, or mixed. The most common locations for GPA-derived inflammatory skull base disease on imaging included the cavernous sinus (12 of 29, 41%) and the orbit (7 of 29, 24%). Conclusion: Establishing the diagnosis of skull base GPA remains challenging. Cranial neuropathy is diverse in presentation and often mimics more common conditions. Imaging findings are also unpredictable and frequently nonspecific. Careful review of patient history, clinical presentation, serology and biopsy results, and imaging can reveal important clues toward the diagnosis.