Enrico Martin

255 Abstract Background Malignant peripheral nerve sheath tumors (MPNSTs) are aggressive soft tissue sarcomas and their resection may lead to serious morbidity. Postoperative motor and sensory deficits are under-reported in the literature and functional reconstruction is infrequently carried out. This study aimed to identify the incidence of postoperative motor and sensory deficits in malignant peripheral nerve sheath tumors (MPNST) and patient risk factors for these deficits. A secondary objective was investigating the outcomes of functional reconstructions. Methods Postoperative function and treatment of MPNSTs diagnosed from 1988- 2019 in 10 cancer centers was obtained. Patients with and without function loss were compared, defined by <M3 motor grade or critical sensory loss. Critical sensation was defined as partial or complete loss of hand, foot, or buttocks sensation. Results Seven-hundred-fifty-six patients (33.4% neurofibromatosis type 1, NF1) were included. MPNSTs originated in 34.4% from a major nerve. Of 658 surgically treated patients, 27.2% had <M3 muscle power and 24.3% critical sensory loss. Amputations were carried out in 61 patients. Risk factors for motor and sensory loss included patients with NF1, symptomatic, large (≥5cm), deep-seated, extremity, and plexus tumors originating from major nerves (all p<0.05). Twenty-six patients underwent functional reconstructions. The majority (64%) of these patients regained at least M3 muscle power and 33% M4 despite 86% receiving multimodal therapy. Conclusion Resection of MPNSTs commonly results in motor and sensory deficits. Patients with NF1, symptomatic, large, deep-seated tumors, and arising from major nerves were at higher risk for developing postoperative morbidity. Functional reconstructions are infrequently performed, but can improve functional outcomes. 11