The patient

A 64-year-old woman tripped after “missing a step,” fracturing her left tibial plateau and resulting in deformity of the joint. This was managed conservatively, with a leg brace removing weight from the extremity. She developed persistent numbness and tingling in her left leg, as well as weakness. She was evaluated in the Norton Neuroscience Institute outpatient neurology clinic by neuromuscular medicine specialist Richard A. Lewis, M.D., and an electromyography (EMG) test was recommended.

The challenge

The EMG revealed an issue with her left sciatic nerve, apparently above the leg injury. She was subsequently referred for an MRI of the left femur and then of the left pelvis, which revealed an approximately 4-centimeter lesion, presumed schwannoma or nerve sheath tumor, growing on her left sciatic nerve.

The physicians

Richard A. Lewis, M.D.
Neurologist and neuromuscular medicine specialist
Norton Neuroscience Institute

Abigail J. Rao, M.D.
Functional neurosurgeon, spine surgeon, and brain and tumor neurosurgeon
Norton Neuroscience Institute

The solution

The patient was referred to a neurosurgeon with specialized training in peripheral nerve surgery, Abigail J. Rao, M.D., with Norton Neuroscience Institute. After extensive review of the patient’s records and history, Dr. Rao and the patient discussed various management options: surgical resection of the tumor, radiographic observation of the tumor and biopsy of the tumor.

The result

Ultimately, it was hypothesized that the lesion on her sciatic nerve may have weakened her leg and contributed to her fall. However, on examination, the patient was now without weakness. She did develop numbness of the foot only after her fall, which may have resulted from a mild stretch injury to the nerve during the fall, with some slow improvement (typical of the timecourse of resolution of peripheral nerve symptoms).

The patient later reported that she had a biopsy of this tumor approximately 25 years ago, with pathology resulting as benign. She was advised by her prior surgeon to follow up frequently with imaging, but neglected to do so for the past 12 years. A radiology report from 12 years ago was discovered, showing that over 12 years, the tumor had grown a maximum of 4 millimeters. This slow rate of growth, combined with minimal clinical symptoms and the reported benign pathology, reinforce that the tumor is likely benign. As such, radiographic follow-up is a reasonable option. With surgical resection, motor symptoms, when present, are more likely than sensory symptoms to resolve. A repeat biopsy was not felt necessary. The patient opted for close radiographic follow-up of the tumor, and orthopedic joint replacement for the deformity of her joint resulting from the fall.