Spinal Schwannoma Mimicking Discogenic Low Back Pain: A Case Highlighting Valsalva-Induced Provocation.

Abstract

While low back pain is a common complaint in physiatry clinics, atypical presentations require astute clinical reasoning to prevent delayed diagnoses of severe spinal pathologies. We present a 43-year-old female with a two-month history of insidious right low back and gluteal pain, accompanied by new-onset bilateral lower limb pitting edema. The initial symptom distribution closely resembled lumbosacral discodural pain; however, the presence of multiple red flags-including constant pain and pain in a supine position-suggested a non-mechanical etiology. Physical examination yielded positive provocation signs suggesting simultaneous lumbar, sacroiliac, and hip joint involvement, without true radicular symptoms. Provocative maneuvers, including anterior distraction and FABER tests, elicited positive responses only during breath-holding. This "Valsalva effect" suggested an intrathecal lesion. Magnetic resonance imaging confirmed a 24×13×12 mm intradural extramedullary schwannoma at the L1-L2 level compressing the conus medullaris. Surgical resection led to complete resolution of both the musculoskeletal symptoms and the lower limb edema. This concurrent resolution implies that the edema was neurogenic in origin, resolving once sympathetic vasomotor control was restored. This case underscores the added diagnostic utility of Valsalva-augmented physical examinations and highlights neurogenic dependent edema as an underrecognized autonomic manifestation of spinal tumors.