title: Quantitative evaluation of median nerve motor function in carpal tunnel syndrome using load cell : correlation with clinical, electrodiagnostic, and ultrasonographic findings.
abstract: OBJECTIVE
  Major complaints of carpal tunnel syndrome (CTS) are sensory components. However, motor deficit also impedes functional status of hand. Contrary to evaluation of sensory function, the objective, quantitative evaluation of median nerve motor function is not easy. The motor function of median was evaluated quantitatively using load cell and its correlation with findings of electrodiagnostic study (EDS) was evaluated.
  
  
  METHODS
  Objective motor function of median nerve was evaluated by load cell and personal computer-based measurement system. All of the measurement was done in patients diagnosed as having idiopathic CTS by clinical features and EDS findings. The strength of thumb abduction and index finger flexion was measured in each hand three times, and the average value was used to calculate thumb index ratio (TIR). The correlation of TIR with clinical, EDS, and ultrasonographic findings were evaluated.
  
  
  RESULTS
  The TIR was evaluated in 67 patients (119 hands). There were 14 males and 53 females, mean age were 57.6 years (range 28 to 81). The higher preoperative nerve conductive studies grade of the patients, the lower TIR was observed [p<0.001, analysis of variance (ANOVA)]. TIR of cases with thenar atrophy were significantly lower than those without (p<0.001, t-test). TIR were significantly lower in patients with severe median nerve swelling in ultrasonography (p=0.042, ANOVA).
  
  
  CONCLUSIONS
  Measurements of median nerve motor function using load cell is a valuable evaluation tool in CTS. It might be helpful in detecting subclinical motor dysfunction before muscle atrophy develops.
authors.affiliation: Department of Neurosurgery, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Dong Hwan
authors.initials: DH
authors.lastname: Kim
authors.forename: Sung Bae
authors.initials: SB
authors.lastname: Park
authors.forename: Sang Hyung
authors.initials: SH
authors.lastname: Lee
authors.forename: Young-Je
authors.initials: YJ
authors.lastname: Son
authors.forename: Gih Sung
authors.initials: GS
authors.lastname: Chung
authors.forename: Hee-Jin
authors.initials: HJ
authors.lastname: Yang
keywords: Carpal tunnel syndrome; Electrodiagnostic study; Load cell; Thumb abduction strength; Ultrasonography