Malignant Peripheral Nerve Sheath Tumors of the Brachial Plexus: A Single-Center Experience on Diagnosis, Management, and Outcomes.

INTRODUCTION: The incidence of malignant peripheral nerve sheath tumors (MPNSTs) is 0.001%. Commonly, MPNST arise in neurofibromatosis; however, they can occur sporadically, de novo or from a preexisting neurofibroma. Malignant peripheral nerve sheath tumors are aggressive tumors with high rates of local recurrence and metastasis. The prognosis is poor with 5-year survival rates of 15% to 50%. Unfortunately, given the rarity of these tumors, it is not clear how to best manage these patients. The purposes of this study were (1) to discuss our experience with MPNST and particularly our difficulties with diagnosis and management, and (2) to review the literature. MATERIALS AND METHODS: We report on all tumors of the brachial plexus excised between 2013 and 2019. We report 3 cases of MPNST, their treatment, and their outcomes. RESULTS: Thirteen patients underwent surgical excision of an intrinsic brachial plexus mass. Three of these patients (2 male, 1 female; average age, 36 years) were diagnosed with an MPNST. Two patients with an MPNST had neurofibromatosis type 1. All patients with an MPNST had a tumor >8 cm, motor and sensory deficits, and pain. All 3 patients with MPNST underwent a magnetic resonance imaging (MRI) before diagnosis. The average time from initial symptom onset to MRI was 12.3 months. Only 1 of the MRIs suggested a malignant tumor, with no MRI identifying an MPNST. One patient underwent an excisional biopsy, and 2 had incisional biopsies. Because of the lack of diagnosis preoperatively, all patients had positive margins given the limited extent of surgery. Returning for excision in an attempt to achieve negative margins in a large oncologically contaminated field was not possible because defining the boundaries of the initial surgical field was unachievable; therefore, the initial surgery was their definitive surgical management. All patients were referred to oncology and received radiation therapy. CONCLUSIONS: Malignant peripheral nerve sheath tumors must be suspected in enlarging masses (>5 cm) with the constellation of pain, motor, and sensory deficits. Computed tomography- or ultrasound-guided core needle biopsy under brachial plexus block or sedation is required for definitive diagnosis to allow for a comprehensive approach to the patient's tumor with a higher likelihood of disease-free survival.

Reconstruction of Quadriceps Function Using a Single Functional Gracilis Muscle Transfer With an Adductor Longus Nerve to Femoral Nerve Branch of the Rectus Femoris Nerve Transfer.

BACKGROUND: A femoral nerve injury may result in cutaneous sensory disturbances of the anteromedial thigh and complete paralysis of the quadriceps femoris muscles resulting in an inability to extend the knee. The traditional mainstay of treatment for femoral neuropathy is early physiotherapy, knee support devices, and pain control. Case reports have used the anterior division of the obturator nerve as a donor nerve to innervate the quadriceps femoris muscles; however, a second nerve transfer or nerve grafting is often required for improved outcomes. We suggest a novel technique of combining an innervated, pedicled gracilis transfer with an adductor longus to rectus femoris nerve transfer to restore the strength and stability of the quadriceps muscles. METHODS: This is a case series describing the use of a pedicled gracilis muscle transposed into the rectus femoris position with a concomitant nerve transfer from the adductor longus nerve branch into the rectus femoris nerve branch to restore quadriceps function after iatrogenic injury (hip arthroplasty) and trauma (gunshot wound). RESULTS: With electrodiagnostic confirmation of severe denervation of the quadriceps muscles and no evidence of elicitable motor units, 2 patients (average age, 47 years) underwent a quadriceps muscle reconstruction with a pedicled, innervated gracilis muscle and an adductor longus to recuts femoris nerve transfer. At 1 year follow-up, the patients achieved 4.5/5 British Medical Research Council full knee extension, a stable knee, and the ability to ambulate without an assistive aid. CONCLUSIONS: The required amount of quadriceps strength necessary to maintain quality of life has not been accurately established. In the case of femoral neuropathy, we assumed that a nerve transfer alone and a gracilis muscle transfer alone would not provide enough stability and strength to restore quadriceps function. We believe that the restoration of the quadriceps function after femoral nerve injury can be achieved by combining an innervated, pedicled gracilis transfer with an adductor longus to rectus femoris nerve transfer with low morbidity and no donor defects.