Sonographic findings of the median nerve and prevalence of carpal tunnel syndrome in patients with Parkinson's disease.

PURPOSE: Parkinson's disease (PD) is a chronic progressive disorder which is characterized by rest tremor, akinesia or bradykinesia and rigidity. Carpal tunnel syndrome (CTS) is caused by compression of median nerve and can occur as a result of repetitive trauma. The aim of this study was to estimate the prevalence of CTS in PD and evaluate the median nerve sonographically.
MATERIALS AND METHODS: Fifty-three wrist of 29 patients with PD were included in the study according to Hoehn and Yahr (H&Y) clinical stage and divided into two groups. The first group consisted of 29 wrists of patients with mild PD (H&Y stage I-II). The second group consisted of 24 wrists of patients with severe PD (H&Y stage III-IV). Thirty-six wrists of 20 age-matched patients were used as control group. Both of the patients with PD and control group underwent sonography and electromyography (EMG). Axial sonograms of the median nerve were obtained at the level of distal radioulnar joint (level 1) and at the level of pisiform bone in the carpal tunnel (level 2). At each level, the cross-sectional area of the median nerve and flattening ratio were calculated.
RESULTS: There was no significant difference for all parameters, except one parameter, between the patients with PD and control group, and also among mild and severe groups of PD and control group (p>0.05). Interestingly, amplitude of median nerve in the second finger was significantly lower in PD patients than control group within normal limits (p=0.010). Of all wrists of PD patients, 13 (24.4%) have been diagnosed as CTS and 7 (19.4%) control wrists had CTS. Median nerve cross-sectional area of CTS patients were more than 10mm(2) in 6 (46%) wrists of PD patients but in only 1 (14%) control wrist at each level. Although it was not statistically significant, there was higher cross-sectional area at each level in patients with severe PD (level 1: 10.43+/-2.30 mm(2), level 2: 10.35+/-3.19 mm(2)) than patients with mild PD (level 1: 9.93+/-2.61 mm(2), level 2: 9.51+/-2.83 mm(2)) and control group (level 1: 9.69+/-3.19 mm(2), level 2: 9.07+/-3.61 mm(2)).
CONCLUSION: PD may pose a risk for the development of CTS due to the repetitive movement of tremor. Although sonography is not an ideal method of diagnosis for CTS, it may take our attention for indicating CTS in patients with PD especially in severe ones.