827 - Successful Treatment of Peripheral Nerve Sheath Tumor related-pain with Perineural Steroid Injection: A Case Report

Case Diagnosis: NF-1-mediated pain secondary to neurofibroma sciatic nerve compression.

Case Description: A 21 year-old female with type 1 neurofibromatosis (NF1) presented complaining of several years of dull, intermittent left-sided buttock pain radiating into the leg. She denied trauma, recent fevers, saddle anesthesia, and bowel or bladder dysfunction. Physical examination was notable for tenderness over the left piriformis region, 3+ bilateral lower extremity reflexes, and positive straight leg raise and slump tests on the left. Lumbar MRI revealed a 3.1 cm lesion in the ischiogluteal space with mass effect on the sciatic and inferior gluteal nerves. The pain persisted despite two months of physical therapy. An ultrasound-guided left ischiogluteal perineural steroid injection was offered for symptomatic relief. The left sciatic neurofibroma was visualized on ultrasound, and 2cc 0.5% Lidocaine/ 1cc Dexamethasone (10 mg/ml) was directed in the perineural space. One month later, the patient reported resolution of LLE pain.

Discussions: NF1 pain is poorly understood, but descriptions of radicular pain are well-documented. Lumbar radiculopathy was originally considered given this patient’s radicular complaints and positive dural tension signs, but imaging clarified the etiology. There are presently no approved treatments for NF1-related pain. Patients historically use NSAIDs, acetaminophen, alone or in combination with prescription pain medications. Surgical excision is considered for large symptomatic neurofibromas like this; however, surgical intervention bears significant morbidity. There is sparse literature regarding the efficacy of ultrasound-guided perineural steroid injection in NF1 patients for treatment of benign peripheral nerve sheath tumor compressions.

Conclusions: This case describes the utility of perineural steroid injections for symptomatic relief of NF1 neurofibroma-related pain. Perineural steroid injections should be considered when neurofibroma-related pain fails to respond to other conservative treatment. Steroid injections provide an alternative to oral medicinal management and avoid the often morbid risks of surgical intervention.