2025 Proffered Presentations
S014: UNDIAGNOSED CRANIAL NEUROPATHIES AND THE ROLE OF ENDOSCOPIC PTERYGOPALATINE FOSSA DISSECTION FOR TISSUE DIAGNOSIS
Matthew J Kabalan, MD; Pablo F Recinos, MD; Varun Kshettry, MD; Raj Sindwani, MD; Cleveland Clinic Foundation
Introduction: Cranial neuropathies of insidious onset and perplexing origin are a rare presenting manifestation of neurotropic metastatic malignancies. In some cases, the pterygopalatine fossa (PPF) may provide an amenable biopsy site that endoscopic skull base surgeons can access through a PPF dissection approach, facilitating tissue diagnosis and accelerating treatment for patients.
Methods: Retrospective review of nine cases at our institution (between November 2014 to July 2024) in which patients who presented with cranial neuropathies of unknown origin and suspected lesions of the PPF underwent an endoscopic, endonasal PPF dissection approach for tissue diagnosis. Variables including patient age at diagnosis, sex, race, smoking history, alcohol and other drug use, history of previous malignancy, immunosuppression, presenting symptoms and duration, imaging findings, extent of surgical approach, and pathology results were analyzed.
Results: The most common presenting symptoms included trigeminal numbness (89% of patients; often most severe in the V2 division, though some patients had dense trigeminal numbness in all divisions); trigeminal neuralgia (33%); additional facial nerve palsy (33%); and varying degrees of ophthalmoplegia (44%). A wide range of symptom duration was seen, ranging from six months to six years. Some of the more frequent areas of involvement seen on MRI in these patients included branches of cranial nerve (CN) V (100%), Meckel’s cave (100%), the PPF (78%), and the cavernous sinus (44%). Post-contrast enhancement of lesions characterized the MRI appearance
Successful tissue diagnosis was obtained in all nine patients (100%) through an endoscopic PPF dissection. One patient had undergone previous facial nerve biopsy at another center which was inconclusive. The most common pathology encountered was squamous cell carcinoma seen in over half of the patients (5/9, 56%). Other pathologies encountered were metastatic melanoma, metastatic adenoid cystic carcinoma, chronic lymphocytic leukemia, and primary extramarginal zone B cell lymphoma. The majority of patients (6/9, 67%) had a history of skin lesions: 4/9 (44%) had a history of cutaneous malignancy (two melanoma and two squamous cell carcinoma), while two others had undergone removal of skin lesions whose histopathology was unknown.
Conclusions: The PPF is a familiar surgical corridor for endoscopic skull base surgeons. Insidious onset of cranial neuropathy can be a vague manifestation of a neurotropic metastatic malignancy, and the diagnosis may therefore confound clinicians. A high index of clinical suspicion must be maintained and MRI with contrast obtained when disease is suspected. A prior history of cutaneous malignancy should be specifically explored. Our approach to biopsy of the PPF, vidian nerve, or V2 can be direct, expeditious, and carries low morbidity as oftentimes these nerves are already dysfunctional. Intraoperative frozen section is helpful in expediting diagnosis (and therefore treatment) and mitigating the risk of needing a second trip to the operating room for additional tissue. A reasonable sequence in obtaining tissue to send for frozen section analysis might include biopsy of the PPF contents first, followed by the vidian nerve, followed by CN V2 and/or its branches, thereby limiting potential morbidity.