Cerebral and clinical effects of short-term hand immobilisation

Abstract

In this work, functional changes in the sensorimotor cortex following unilateral hand immobilisation were investigated in 11 healthy volunteers. Sensory and motor function of both hands was also assessed. Cortical activation was monitored with functional magnetic resonance imaging at 3 T. All examinations were performed prior to and directly after 72 h of immobilisation of the dominant hand and wrist. Following unilateral immobilisation, cortical activation increased substantially during tactile stimulation of the non-immobilised hand. This was particularly evident in the ipsilateral somatosensory cortex. Additionally, a redistribution of hemispheric dominance towards zero lateralisation was seen. A bilateral cortical activation increase was also seen during performance of a finger-tapping task by the non-immobilised hand, although this increase was less prominent than during tactile stimulation. In contrast, performance of the finger-tapping task with the immobilised hand resulted in an activation decrease, predominantly in the ipsilateral sensorimotor cortex. This site was anatomically close to the regional activation increase of the non-immobilised hand. These functional changes were associated with reduced grip strength, dexterity and tactile discrimination of the immobilised hand, and simultaneously improved tactile discrimination of the non-immobilised hand. This suggests that brain adaptation following hand immobilisation includes inter-hemispheric dynamics. In summary, the improved sensory function of the non-immobilised hand following unilateral immobilisation is associated with cortical expansion, predominantly contralateral to the immobilised hand, and a redistribution of hemispheric dominance. Both cortical and clinical effects of immobilisation were identified after 72 h, suggesting rapid inter-hemispheric plasticity using existing neural substrates.

Dissociating effect of upper limb non-use and overuse on space and body representations

“…While previous studies have shown symmetric effects between the two hemispheres on motor and somatosensory domains after the non-use of one limb and the consequent overuse of the free one (Lissek et al, 2009;Avanzino et al, 2011;Weibull et al, 2011), with the present results an asymmetry emerges. We found that PPS boundaries contracted around the non-used arm, but did not change around the overused limb (Exp.…”

“…Thus, we evaluated two opposite effects: the non-use of the right arm and the concurrent overuse of the left limb. In line with previous studies, the two different effects were evaluated separately for both sides (Avanzino et al, 2011;Lissek et al, 2009;Weibull et al, 2011).…”

Short-term immobilization influences use-dependent cortical plasticity and fine motor performance

“…Huber et al (2006) and Moisello et al (2008) both reported that 12 hours of left arm immobilisation produces increased normalised hand-path area and variability during out-and-back movements. Furthermore, Weibull et al (2011) reported that 3 days of right hand immobilisation produces deficits in fine motor dexterity (assessed using the Purdue pegboard) and Ngomo et al (2012) showed that 4 days of immobilisation of the non-dominant hand significantly impedes the ability to acquire a novel motor task. Within the current study, both groups demonstrated motor learning by increasing the number of pegs placed within each session, suggesting that motor performance improved with training irrespective of immobilisation.…”

Distal forelimb representations in primary motor cortex are redistributed after forelimb restriction: a longitudinal study in adult squirrel monkeys

“…Whereas most studies of limb immobilization are complicated by their purpose in treating orthopedic injuries, a few studies have been performed in healthy volunteers for periods up to 3 wk (Clark et al 2008(Clark et al , 2010Lundbye-Jensen and Nielsen 2008;Weibull et al 2011). Immobilization resulted in significant reduction in contraction torque and strength and alteration of neurophysiological properties, requiring ϳ1 wk for recovery.…”

“…Immobilization resulted in significant reduction in contraction torque and strength and alteration of neurophysiological properties, requiring ϳ1 wk for recovery. Even short-term casting (72 h) resulted in changes in grip strength, dexterity, and tactile discrimination (Weibull et al 2011). Nevertheless, casting up to 3 wk in duration is deemed benign, and any functional deficits are typically transient.…”