Functional Improvement in Cranial Neuropathies From Perineural Cutaneous Squamous Cell Carcinoma After Immunotherapy: A Multicenter Case Series and Review

PURPOSE: Cutaneous squamous cell carcinoma has a propensity for perineural invasion. Treating perineural spread has involved surgery and adjuvant chemoradiation, and more recently, immune checkpoint inhibitors. This study aims to evaluate motor and sensory functional outcomes in patients with cranial neuropathies from perineural spread of squamous cell carcinoma, particularly those undergoing immunotherapy. METHODS: This was a multicenter case series and literature review. RESULTS: Eighteen patients with cranial neuropathies from perineural spread had a mean age of 72.5 ± 9.7 years. Cranial nerves V and VII were most often involved. Treatments included radiotherapy (8/18; 44.4%), chemotherapy (7/18; 38.9%), and/or immunotherapy (11/18; 61.1%), with many receiving a combination of modalities (8/18; 44.4%). Of those receiving immunotherapy, 72.7% (8/11) demonstrated at least partial clinical and/or radiologic tumor response. Among those with functional outcomes documented, half had improvement in sensory/motor nerve function following immunotherapy (4/8; 50%). A literature review identified 55 articles describing 449 patients total with cranial neuropathies from squamous cell carcinoma perineural spread. Combinations of surgery, chemotherapy, and/or radiotherapy were employed, with immunotherapy used in 16 patients. From 5 patients on immunotherapy with documented functional outcomes, all demonstrated at least some improvement. CONCLUSION: Immunotherapy plays an evolving role in managing advanced squamous cell carcinoma. Functional improvements in cranial neuropathy were demonstrated in 50% of patients receiving treatment with immunotherapy at a mean of 32.6 months of follow-up. This may hold important implications for the timing of surgical intervention, particularly in the case of cranial nerves V and VII palsies.