Cervical myelopathy causing numbness and paresthesias in lower extremities: A case report identifying the cause of a false positive Sharp-Purser test.

INTRODUCTION: The patient was referred to an outpatient physical therapy clinic for lumbar radiculopathy by a primary care physician and subsequently referred for imaging due to suspicion of cervical myelopathy. The case highlights the clinical reasoning of the physical therapist differentiating between lumbar stenosis, cervical myelopathy, and upper cervical instability. To the author's knowledge, this is the only case report in the literature to describe the mechanism that could underpin a false positive Sharp-Purser test (SPT). The case also highlights the importance of interpreting the outcomes of special tests cautiously.

CASE DESCRIPTION: A 55-year-old female was referred to outpatient physical therapy for lumbar radiculopathy. The patient's complaint was a one-year history of intermittent bilateral lower buttock paresthesias radiating to the bilateral posterior thighs. She reported a three-month history of bilateral anterior thigh numbness that would present after sitting for 30 minutes. Lumbar stenosis was initially suspected, however the patient's failure to improve but rather worsen with flexed postures suggested this diagnosis was improbable. The patient experienced bilateral anterior thigh numbness with active cervical flexion, and had a reduction in symptoms with the SPT.

OUTCOMES: Magnetic resonance imaging revealed multi-focal disc-osteophyte complexes with central canal stenosis from C4-7. The patient underwent an anterior cervical discectomy and fusion with a good outcome.

DISCUSSION: A large disc herniation causing central canal stenosis could underpin a false positive SPT. Special tests should always be used with caution, as they can lead to inaccurate diagnoses if there is a false positive.