NEUROPHYSIOLOGICAL DETERMINATION OF THE CARPAL TUNNEL SYNDROME IN PATIENTS WITH CHRONIC DEMYELINATING POLYNEUROPATHY

Abstract

Cocito D., Isoardo G., Ciaramitaro P., Santomassimo P., Durelli L., Bergamasco B.Dipartimento di Neuroscienze, Università di Torino. OBJECT: To determinate a specific neurophysiological method to confirm the diagnosis of carpal tunnel syndrome (CTS) in patients affected with chronic inflammatory demyelinating polyneuropathy (CIDP), particularly in patients affected with CIDP or with demyelinating polyneuropathy (PN) with IgM‐paraproteinemia and anti‐MAG antibody (MAG‐PN), both of them having symptoms and signs suggestive of CTS. PATIENTS AND METHODS: We evaluated five groups of patients: a) 8 CIDP e 2 MAG‐PN (20 hands), mean age 58 years, range 30–67, without clinical signs of CTS; b) 6 MAG‐PN (11 hands), mean age 52, range 45–65, with clinical signs of CTS (CTS MAG‐PN); c) 7 CIDP (11 hands), mean age 41, range 34–60, with clinical signs of CTS (CTS CIDP); d) 45 CTS (60 hands), mean age 44, range 25–68; e) 23 healthy controls (46 hands), mean age 40, range 22–65. The diagnosis of CTS is based on clinical criteria including nocturnal or activity‐related pain, paresthesia, and positive Phale's or Tinel's signs. Electrophysiological diagnosis of demyelinating chronic polyneuropathy was made according to Rotta et al (J. Neurol. Sci. 173, 2000). The following electrophysiological parameters were evaluated: a) Antidromic sensory conduction velocity of median and ulnar nerve between wrist and, respectively, second and fifth finger. b) Fistal motor latency (DML) to abductor pollicis brevis and abductor digiti minimi muscles and the elbow to wrist motor conduction velocity of median and ulnar nerve. c) Terminal Latency Index (TLI) of median and ulnar nerve. d) Motor latency of the median nerve to second lumbrical and of ulnar nerve to second interosseous muscle and their difference (L‐I DIFF). e) Compound Sensory Index. RESULTS: L‐I DIFF was the most sensitive electrophysiological parameter in order to detect presence of CTS in patients with CIDP or MAG‐PN.