To evaluate the treatment response of patients with clinical and supportive laboratory features of chronic inflammatory demyelinating polyneuropathy (CIDP) who lack evidence of demyelination on nerve conduction studies (NCS).  

Retrospective chart review was conducted on 232 consecutive patients seen at our center over a 20-year period who met clinical criteria for CIDP and were treated with disease-modifying immunosuppressive therapy.  Patients were selected who did not have EFNS/PNS NCS criteria of demyelination, but who did have supportive CSF, MRI, or ultrasound laboratory findings consistent with CIDP. A positive treatment response was defined as at least a 1-point improvement in the modified Rankin scale MRS, or a 4-point increase in the Medical Research Council sum score (MRCSS), as MRS and MRC data was available for all patients.

20 patients met criteria. 16/17 (94%) had CSF protein > 45 mg/dL. 6/14 (43%) had lumbar root enhancement on MRI. 4/6 (67%) had enlargement of proximal nerve segments on ultrasound. 18 patients (90%) received IVIg, 10 (50%) corticosteroids, one (5%) PLEX, and six (30%) other immunomodulatory therapies. 12 patients (60%) had a positive treatment response on the MRCSS, or MRS. The presence of lumbar root enhancement or enlarged proximal nerve segments on ultrasound predicted a positive treatment response (p<.013). Elevated CSF protein alone did not predict improvement.