Lesser occipital nerve damage after retrosigmoid craniotomy repaired with processed nerve allograft

Background and importance: The retrosigmoid approach provides a robust corridor to cerebellopontine angle (CPA) pathology, but postoperative headache syndromes can cause significant patient distress. The lesser occipital nerve (LON) is in danger of injury during a retrosigmoid approach, and LON injury may present as occipital neuralgia with hypesthesia, dysesthesia and/or allodynia in the distribution of the LON. There are a number of treatment alternatives for refractory occipital neuralgia, but LON repair with processed nerve allograft has not previously been reported. Clinical presentation: A 42-year-old female was referred to peripheral nerve clinic for neuropathic pain, numbness and discomfort in a right LON distribution. Her history was significant for right retrosigmoid craniotomy for fenestration of a symptomatic CPA arachnoid cyst 2.5 years prior. Exam was significant for allodynia and reduced sensation. Exploration of the retrosigmoid incision revealed a damaged, scarred down LON. The nerve was trimmed and a 3 cm cadaveric, processed nerve allograft was interposed between the proximal and distal segments, secured without tension. The patient exhibited improvement in her neuropathic pain at follow-up. Conclusion: LON injury during retrosigmoid craniotomy can lead to occipital neuralgia and significant patient distress. Surgeons should be aware of the LON's course relative to retrosigmoid incisions. Repair of the injured nerve with processed cadaveric nerve allograft deserves continued investigation for treating LON damage.