Ultrasound changes of the carpal tunnel in patients receiving long-term hemodialysis: a cross-sectional and longitudinal study.
BACKGROUND
Carpal tunnel syndrome (CTS) is one of the major problems of long-term hemodialysis (HD), but sometimes difficult to distinguish from uremic or diabetic neuropathy by clinical symptoms.


METHODS
To evaluate the diagnosis of CTS more precisely, we examined the ultrasonographic alterations of the carpal tunnel and tendons of 90 wrists from 45 patients undergoing HD for more than 5 years. We measured the thickness of the palmar radiocarpal ligament (PRL), corresponding to the posterior wall of the carpal tunnel (CT), and the width of the CT, and compared those values with sensory (SCV), motor conduction velocity (MCV) of the median nerve and clinical symptoms. In addition, we longitudinally measured CT and PRL in the same patients for 5 years, and compared ultrasonographic changes and clinical parameters.


RESULTS
A linear positive relationship was found between HD duration and PRL thickness (r = 0.43, p < 0.01) or CT width (r = 0.53, p < 0.01). CT diameter was negatively correlated with MCV (r = -0.30, p < 0.01) and SCV (r = -0.33, p < 0.04). PRL thickness was also inversely correlated with MCV (r = -0.44, p < 0.01) and SCV (r = -0.46, p < 0.01) of the median nerve, respectively. The wrists with clinical CTS and/or previous CTS surgery had significantly greater CT and PRL values compared to patients without CTS (CT: 6.1 0.2vs. 8.0+/-0.3 mm,p<0.01;PRL: 1.9+/-0.1 vs. 3.6 +/- 0.2 mm, p < 0.01). There was a significant increase in CT width from 6.2 +/- 0.2 to 7.1 +/- 0.2 mm (p < 0.01) and PRL thickness from 2.4 +/- 0.2 to 2.8 +/- 0.2 mm (p <0.01) during the 5-year observation, respectively. PRL thickness was constantly increased at the rate of 0.4 mm during the study. However, no significant association was found between the 5-year increases in CT and PRL distance and age, gender, the prevalence of diabetes, or laboratory parameters such as blood beta2-microglobulin, pentosidine and Kt/V(urea).


CONCLUSIONS
Our data suggest that echographic evaluation of the wrist tissue thickness was useful to assess the progression of CTS. Serial measurements of the wrist by echography may be helpful to clarify the advance of subclinical CTS in patients receiving long-term HD.
Takahashi
T
T
Matsuyama Hospital, Hamamatsu University School of Medicine, Shizuoka, Japan.
Kato
A
A
Ikegaya
N
N
Takita
T
T
Maruyama
Y
Y
Hishida
A
A
Takahashi
M
M
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002349:Carpal Tunnel Syndrome / Q000000981:diagnostic imaging* / Q000209:etiology / Q000503:physiopathology; D003430:Cross-Sectional Studies; D018450:Disease Progression; D005260:Female; D006801:Humans; D008023:Ligaments, Articular / Q000000981:diagnostic imaging*; D008137:Longitudinal Studies; D008297:Male; D008475:Median Nerve / Q000000981:diagnostic imaging / Q000502:physiology; D008875:Middle Aged; D009431:Neural Conduction / Q000502:physiology*; D006435:Renal Dialysis / Q000009:adverse effects*; D013710:Tendons / Q000000981:diagnostic imaging; D014463:Ultrasonography; D014953:Wrist / Q000000981:diagnostic imaging*