Sectoral schwannomatosis of the sciatic nerve: Clinical and Surgical Aspects

Schwannomas are the most common benign tumors of peripheral nerves and spinal nerve roots. Sectoral schwannomatosis, in turn, is a rare condition (0.58 cases per 1 million people) characterized by multiple tumors affecting a single nerve trunk, with no pathological lesions in other anatomical areas. Unlike systemic forms of neurofibromatosis, sectoral schwannomatosis typically lacks cutaneous manifestations and bilateral vestibular nerve involvement, making diagnosis particularly challenging. Over the past decade, only a few cases of sectoral schwannomatosis involving the sciatic nerve have been reported in the literature. Herein, we present a rare clinical case of a female patient with sectoral schwannomatosis of the sciatic nerve and its branches requiring surgical intervention. Neuroimaging (MRI and ultrasound) revealed multiple mass lesions extending along the sciatic nerve in the distal third of the thigh, as well as along the tibial nerve in the proximal third of the lower leg and the popliteal region. The total length of the involved nerve segment reached up to 20 cm, with tumors exhibiting heterogeneous structure and pronounced vascularization on Doppler imaging. The clinical presentation featured intractable neuropathic pain. No tumors were found in other nerves. The patient underwent surgical removal of five tumor nodules using direct nerve stimulation (intraoperative neuromonitoring), which allowed for clear differentiation between functionally significant nerve fascicles and tumor tissue, thereby preventing their damage. Postoperatively, nerve function was fully preserved, and pain regressed to 1 point on the visual analogue scale within the first five days. A review of the relevant literature is also provided. Given the rarity of this pathology, accumulation of clinical experience is essential; therefore, each identified case of sectoral schwannomatosis warrants a detailed description.