Upper Limb Movement Performance in Individuals Sustaining Mild Traumatic Brain Injuries

Individuals sustaining a mild traumatic brain injury (TBI) continue to have suboptimal upper limb (UL) involvement in daily life. Intensity of task practice is one key factor to promote better motor improvement. Task-practice intensity metrics include number of repetitions/sessions, and this value is currently unknown in people with mild TBI. Kinematic analysis can help estimate the number of repetitions/sessions.

We estimated the minimal number of repetitions for a plateau in performance in an UL pointing task in 10 individuals who had sustained a mild TBI and seven age-matched controls.

All participants performed 45 repetitions and pointed to a central target at arm's length. The TBI group underwent assessments of UL motor impairment, spasticity and activity limitations. The primary outcome was the number of trials to achieve an asymptote in endpoint error. Secondary outcomes included movement speed, straightness, trunk and UL joint ranges of motion.

Clinical assessments revealed absence of motor impairment or activity limitations. However, individuals with mild TBI required more trials (28.5) to reach an asymptote in the pointing movement performance compared to controls (18; p = .005, effect size [ES] = -0.66). They also had more curved movements (1.11 ± 0.06 vs 1.06 ± 0.01; p = .036, ES = 0.64), used more trunk displacement (13.1 ± 3 vs 10.2 ± 2.1 mm; p = .044, ES = 1.09) and had lower ranges of motion in wrist extension (24.8 ± 3.8 vs 17.3 ± 3.4; p = .006, ES = 1.60), elbow extension (144.7 ± 6.8 vs 152.3 ± 6.8°, p = .025, ES = 1.22), shoulder flexion (60.5 ± 5.2 vs 66.6 ± 6.4, p = .046, ES = 1.07) and shoulder horizontal adduction (77.7 ± 5.0 vs 87.4 ± 9.6, p = .014, ES = 1.35).

After sustaining a mild TBI, individuals have deficient UL movement performance. Use of kinematic analyses can help uncover latent deficits in those with perfect scores on clinical assessments.