Identification of static and dynamic postural instability following traumatic brain injury.

Abstract

Quantitative evaluation of static and dynamic aspects of postural instability as a long-term consequence of traumatic brain injury (TBI). Experimental two-group design. Outpatient rehabilitation department. From a consecutive sample of TBI patients at least 6 months after trauma, 20 subjects were selected who complained of reduced gross motor skills but showed no sensorimotor impairments in a standard neurological examination (11 men, 9 women; mean age 36.2 +/- 10.7 years). Thirteen patients had sustained mild, 2 moderate, and 5 severe TBI. Twenty healthy controls were matched for age and gender. None. A dual-plate force platform recorded the amplitude and velocity of the center-of-pressure fluctuations in the anteroposterior (AP) and lateral (LAT) sway directions during quiet standing. Also, the speed and fluency of weight shifting using visual feedback was registered. Both balance tasks were combined with an arithmetic task, whereas quiet standing was also tested with visual deprivation. Compared to controls, TBI patients showed an increase of over 50% in AP and LAT sway, and a weight-shifting speed 20% lower. Dual-task interference was never significant. Visual deprivation was most detrimental for the TBI patients, particularly for LAT sway control. A long-term overall reduction in both static and dynamic control of posture can be present after TBI, even in patients without clear neurological deficits. Force-plate recordings can identify such (latent) balance problems. Visual deprivation during quiet standing appears a simple, sensitive test for postural instability related to sensory integration deficits.