Disclosures: Brendan Mullen, MD: No financial relationships or conflicts of interest

Case Diagnosis: A 52-year-old previously independent male with mechanical fall found to have acute left traumatic sciatic mononeuropathy in the setting of active chronic lumbosacral radiculopathy.

Case Description: The patient presented for electrodiagnostic testing with significant left lower extremity pain and paresthesia after mechanical fall two months prior. He lost balance while ambulating in his bathroom and fell directly onto his left buttock with abrupt hip flexion. Symptoms noted along the left posterior leg into plantar surface of the left foot. He had pain-limited weakness to resistance with left hip flexion, ankle dorsiflexion, and plantarflexion. The pain was significant enough that he started to use bilateral axillary crutches for offloading. Initial work-up included X-rays of left tibia, ankle, and foot which were only remarkable for mild soft tissue swelling.

Setting: Outpatient academic electrodiagnostic laboratoryAssessment/

Results: Nerve conduction testing of the left lower extremity showed no response to left peroneal and tibial motor as well as significantly reduced amplitude of sensory nerve action potentials. Needle testing resulted in deep peroneal, superficial peroneal, tibial, and sciatic-innervated muscles all with profound positive sharp waves indicating acute denervation as well as long-duration and polyphasic motor unit potentials indicating chronic injury with signs of re-innervation. Needle study of the lumbar paraspinal muscles also showed small positive sharp waves at the L5 and S1 levels, indicating chronic but active denervation near the spine.

Discussion: Results were consistent with acute left sciatic mononeuropathy with active denervation in the setting of chronic left lumbosacral radiculopathy. Given the history, patient may have suffered from traction injury or compression from surrounding hematoma to the nerve in the infrapiriform foramen. Further testing to localize the lesion upon further clinical reflection may have included posterior femoral cutaneous nerve conduction or needle study evaluating inferior gluteal nerve.

Conclusion: Providers need to maintain critical thinking of anatomy to accurately diagnose using electrodiagnostic studies.

Level of Evidence: Level V

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/think-outside-the-radiculopathy-box-an-electrodiagnostic-case-report/