CARPAL TUNNEL SYNDROME IN AMYOTROPHIC LATERAL SCLEROSIS AND LATE ONSET CEREBELLAR ATAXIA M. MONDELLI, P. DELLA PORTA, A. ZALAFFI and A. ROSSI From the Institute of Neurological Sciences, Universityof Siena, Italy We report on clinical and electrophysiological findings and management in nine patients who developed carpal tunnel syndrome during the course of amyotrophic lateral sclerosis and late onset cerebellar ataxia, two neurodegenerative diseases. The patients were treated with surgical decom- pression (five cases) and local steroid injections (four cases). Only one showed lasting relief of symptoms and significantly improved distal conduction in the median nerve at follow-up after 2 to 3 months. The symptoms and conduction data remained unchanged in three patients who could be followed for more than 1 year. We think that axonal neuropathy plays an important role in the development of carpal tunnel syndrome in these patients and accounts for the failure of the standard treatments. Journal of Hand Surgery (British and European Volume, 1996) 21B:4.'553-558 Carpal tunnel syndrome (CTS) is the commonest entrap- ment neuropathy, and usually occurs in adults over the age of 30, mainly women. In 1976 to 1980, the incidence of CTS was estimated to be 125 per 100,000 in Rochester, Minnesota, USA (Stevens et al, 1988). Polyneuropathies and systemic diseases predispose to entrapment syndromes in the peripheral nerves. CTS is more frequent in patients on long-term haemodialysis or with diabetes mellitus, rheumatoid arthritis, chronic renal failure, hypothyroidism, acromegaly, multiple myeloma, amyloidosis, hereditary neuropathy with lia- bility to pressure palsy (tomaculous neuropathy) and Guillain-Barr6 syndrome. Studies on the incidence of CTS in subjects with amyotrophic lateral sclerosis (ALS) and late onset cerebellar ataxia (LOCA), two neurodeg- enerative disorders, have not been reported in the litera- ture up to now. We report the clinical and electrophysiological study, management and follow-up of seven patients with ALS and two with LOCA who developed CTS. We also studied eight patients (six with ALS and two with LOCA) who showed only delay of distal conduction in the median nerve without symptoms of CTS. PATIENTS AND METHODS From a population of 143 patients with ALS and 39 with LOCA, observed consecutively at the Laboratory of Neurophysiology of the Institute of Neurological Sciences of Siena University from 1980 to 1993, we selected nine patients (six men and three women), with signs, symptoms and electrophysiological findings sug- gesting CTS and another eight cases with abnormalities of distal conduction in the median nerve only without symptoms of CTS. The details of enrolment of the ALS and LOCA patients have already been reported in previous studies on axonal sensory neuropathy in ALS (Mondelli et al, 1993) and axonal motor and sensory neuropathy in LOCA (Rossi et al, 1985; Mondelli et al 1991; 1992). The first nine patients (cases 1-7, 14, 15 of Table 1) complained of typical symptoms: nocturnal paraes- thesia; morning clumsiness and stiffness in the dominant hand; in four cases the symptoms were bilateral. Hypoaesthesia of the tips of the first three fingers was reported by seven subjects. All nine had one or more of the following clinical signs: Tinel's, Phalen's and increase of symptoms with distal compression. Weakness of the thenar muscles was a constant finding, but it was impossible to evaluate whether it was due to CTS or the neurodegenerative disorder. In ALS patients not only the thenar eminence but also the other intrinsic muscles of the hand, innervated by the ulnar nerve, were atrophied and weak. The other eight subjects (cases 8-13, 16, 17) did not complain of any symptoms of CTS and showed only distal delay of conduction. (Abnormal distal sensory and motor conduction velocit- ies in the median nerve, with differences in distal motor latency and sensory conduction velocity on stimulation of the ring finger between the median and ulnar nerves, of more than 1.5 m/s and 10m/s respectively). In all nine symptomatic cases, except case 1, clinical signs of CTS emerged in the course of their illness, and in five subjects it also became possible to demonstrate it by electromyography and nerve conduction studies. Cases 1 to 4 and 14 were treated surgically with complete division of the flexor retinaculum. In case 1 tenosynovitis of the flexor synovium and an hourglass compression of the nerve were found and neurolysis was performed by incising the epineurium and dissecting the nerve fascicles to free them of fibrosis. The other four patients (cases 5-7 and 15), who complained of less severe symptoms, were treated with two local steroid injections at an interval of 7 to 10 days (15 mg methyl- prednisolone acetate for cases 6 and 7, and 40 mg triamcinolone acetonide for cases 5 and 15). The first clinical and electrophysiological follow-up was per- formed 2 to 3 months later. Further re-examinations were performed in only three cases because four ALS patients had died (cases 1, 2, 4 and 6) and cases 3 and 15 were lost to follow-up. Of the asymptomatic subjects, two died within a year, five patients were re-examined or contacted by 'phone and one was lost to follow-up. 553