Tally counter test as a simple and objective assessment of cervical myelopathy

Abstract

Purpose: To test the usefulness of a novel performance test, the tally counter test (counter test), which uses a hand tally counter to objectively assess the severity of cervical myelopathy.

Methods: Eighty-three patients with compressive cervical myelopathy (mean age 64 ± 13 years) who were undergoing cervical laminoplasty and 280 healthy control subjects (aged 20-89 years) were tested. The subjects were instructed to push the button of a tally counter as many times as possible in 10 s. The average of the right- and left-sided values in each patient was used for analysis. In the patient group, counter test values were compared with Japanese Orthopaedic Association (JOA) and Japanese version of the 36-Item Short Form Health Survey scores preoperatively and 12 months postoperatively.

Results: The average counter test value was significantly lower in patients with myelopathy than age- and gender-matched controls (32.9 ± 10.9 vs. 46.9 ± 8.5, P < 0.0001). The counter test value was significantly higher at 2 weeks postoperatively than preoperatively (P = 0.0014). Counter test values showed a moderate correlation with JOA scores and a weak to moderate correlation with SF-36 physical functioning, role functioning, and role-emotional scores both pre- and postoperatively. The intraclass correlation coefficient of counter test values was high both pre- and postoperatively.

Conclusion: The tally counter test is objective and quantitative assessment method for patients with cervical myelopathy. The test is simple, reliable, and capable of detecting small functional changes.

Fig. 1

Counter test procedure. Subjects were instructed to hold a tally counter with their thumb on the button, and to push the button as many times as possible in 10 s

Fig. 2

Age-dependent changes in counter test results in healthy controls. Counter test values decreased with age (grey circles males, white circles females). There was a strong linear inverse correlation between counter test values and age (Spearman correlation coefficient = −0.819, P < 0.0001). The normal value in male changed according to the equation: value = 68.0–0.31 × age (black line), and in females this equation was: value = 67.6–0.35 × age (grey line)

Fig. 3

Comparison between myelopathy patients and age- and gender-matched control subjects. The average counter test value was significantly lower in patients with myelopathy than in control subjects (32.9 ± 10.9 vs. 46.9 ± 8.5; Mann–Whitney U test, P < 0.0001)

Fig. 4

Receiver operating characteristic (ROC) analysis. ROC analysis demonstrated AUCs of counter test value and grip strength to be 0.886 (black line) and 0.780 (grey line), respectively. The larger AUC of counter test value linear shows that the counter test is superior to grip strength for detecting cervical myelopathy. The optimal counter test cutoff value for detecting cervical myelopathy was 39.5 (sensitivity 83.3 %, specificity 80.4 %)

Fig. 5

Counter test values and grip strengths at different time points after decompression surgery. a Counter test values were significantly higher at 2 weeks postoperatively than preoperatively (one-way ANOVA followed by Bonferroni post hoc test, P = 0.0014). b Grip strength increased postoperatively, but this difference was not significant until 6 months (P = 0.024). * P < 0.05; ** P < 0.01; ^†P < 0.001

Fig. 6

Correlation between an early increase in counter test value and a longer-term increase in the JOA score. The increase in the counter test value at 2 weeks postoperatively was significantly correlated with the increase in the JOA score at 12 months postoperatively (Spearman correlation coefficient = 0.364, P = 0.0012)