Isolating Neurologic Deficits in Cervical Spondylotic Myelopathy: A Case-Controlled Study, Using the NIH Toolbox Motor Battery

Abstract

Background and objectives: Patients with cervical spondylotic myelopathy (CSM) have motor impairments, including weakness, imbalance, and loss of dexterity. The reliable assessment of these symptoms is critical for treatment decisions. This study aimed to determine, for the first time, the use of the NIH Toolbox motor battery (NIHTBm) in the objective assessment of motor deficits in patients with CSM.

Methods: Patients with symptoms and MRI evidence of CSM and age-matched healthy controls (HC), with no evidence of spinal disorder or surgery were included in this case-control study based on our inclusion and exclusion criteria. We performed motor tests, dexterity, gait speed, grip strength, and balance tests, using the NIHTBm in patients with CSM and HCs. Motor impairment rates were determined in patients with CSM based on the NIHTBm scores. We determined the association between NIHTBm scores and patient-reported outcome scores; patient-reported outcome measures (the modified Japanese Orthopedic Association [mJOA] and Nurick grade) to determine the association. One-way analysis of variance was used to analyze group differences and the Spearman rank correlation to determine the relationship between assessment scores.

Results: We enrolled 24 patients with CSM with a mean age (SD) of 57.96 (10.61) years and 24 age-matched HCs with a mean age (SD) of 53.17 (6.04) years in this study. Overall, we observed a significant decrease in the motor function T-scores mean (SD): dexterity 31.54 (14.82) vs 51.54 (9.72), grip strength 32.00 (17.47) vs 56.79 (8.46), balance 27.58 (16.65) vs 40.21 (6.35), and gait speed 0.64 (0.18) vs 0.99 (0.17) m/s, in patients with CSM compared with that in HCs. The lower extremity dysfunction scores on the NIHTBm, balance (ρ = -0.67) and gait speed (ρ = -0.62), were associated with higher Nurick grades. We observed a similar but weaker association with the Nurick grades and NIHTBm tests: dexterity (ρ = -0.49) and grip strength (ρ = -0.31) scores. The total motor mJOA showed a positive but weak association with NIHTBm scores, gait speed (ρ = 0.38), balance (ρ = 0.49), grip strength (ρ = 0.41), and dexterity (ρ = 0.45).

Discussion: Patients with CSM had significantly lower NIHTBm scores compared with HCs. The results from the NIHTBm are consistent with the clinical presentation of CSM showing patients have motor impairments in both upper and lower extremities. As a neurologic-specific scale, NIHTBm should be used in the evaluation and clinical management of patients with CSM.

Figure 1. Clinical Assessment Scores of Participants

(A) Bar graphs displaying mJOA scores, the total motor-mJOA (tm-mJOA), and Nurick scores for HCs and patients with CSM. (B) Bar graphs displaying the difference in dexterity and grip strength scores (dominant and nondominant hand scores). (C) Balance scores. (D) Gait speed scores between patients with CSM and HCs. **p < 0.01, ***p < 0.001, ****p < 0.0001. CSM = cervical spondylotic myelopathy; HCs = healthy controls; mJOA = modified Japanese Orthopedic Association.

Figure 2. Relationships Between Nurick Grade and NIHTBm Scores in Patients With CSM

Scatterplots showing the correlation between the Nurick grades and (A) dexterity (dominant hand) scores. (B) Grip strength (dominant hand) scores. (C) Balance scores. (D) Gait speed scores. CSM = cervical spondylotic myelopathy; NIHTBm = NIH Toolbox motor.

Figure 3. Correlation Between tm-mJOA and NIHTBm Scores

(A) Scatterplot showing the correlation between the dexterity (dominant hand) and tm-mJOA scores. (B) The correlation between grip strength (dominant hand) and tm-mJOA. (C) The correlation between the balance score and tm-mJOA score. (D) The correlation between gait speed and tm-mJOA score. NIHTBm = NIH Toolbox motor; Tm mJOA = total motor modified Orthopedic Association score.