CIDP-induced spinal canal obliteration presenting as lumbar spinal stenosis

A 59-year-old woman with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) in long-lasting remission presented with symptoms of lumbar spinal stenosis. Weakness in the lower limbs as well as hypesthesia and decreased sense of vibration in the L5/S1 segment were noted.

MRI of the spine (figure) revealed lumbar spinal canal stenosis due to pronounced enlargement of cauda equina fibers and bilateral thickening of the lumbar nerve roots. Fat suppressed postcontrast T1-weighted images showed nerve root and pial enhancement as reported previously.¹

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Figure. Sagittal (A through C) and parasagittal MR slices of the lumbar spine in a patient with chronic inflammatory demyelinating polyradiculoneuropathy. (A) T2-weighted image, showing lack of regular fluid-isointense signal, due to swollen cauda equina fibers (arrows). (B) Corresponding T1-weighted, fat-saturated image. Diffuse cauda equina enhancement (arrows) is depicted, indicating inflammation. (C) Parasagittal T1-weighted, fat-saturated image. Enlarged and enhancing root fibers are shown, exiting the neuroforamen (arrows).

The diagnosis of CIDP was confirmed by characteristic findings in electrophysiologic as well as CSF studies.² Electrophysiologic findings included abnormal conduction velocity, prolonged F-wave latencies, and partial conduction block. CSF studies depicted an elevated CSF protein concentration (84.6 mg/dL) without pleocytosis.

The patient was treated with IV corticosteroids and rapidly responded with complete remission of the radicular pain and major improvement of the hypesthesia.

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