Vestibulospinal responses in motor incomplete spinal cord injury

Objective Postural instability limits ambulatory capacity in patients with spinal cord injury (SCI). Galvanic vestibular stimulation (GVS) was used to investigate the integrity of vestibulospinal pathways and related changes in postural responses in SCI. Methods Binaural bipolar galvanic stimuli of 400 ms duration and 3 mA intensity were applied in 8 motor incomplete SCI and 8 control subjects who stood facing towards the left. EMG responses were recorded from the right soleus muscle and the trajectory of the centre of pressure (CoP) was measured with a force plate. Results There was no difference in excitability and amplitude of the responses between the groups. However, the latency and duration of the medium latency EMG response and all CoP responses were significantly longer in the SCI group. Additionally, postural stability was reduced in the SCI group, as shown by a greater tendency to fall due to GVS. Conclusions Despite early EMG responses proving the basic connectivity of the direct vestibulospinal pathways, the delayed GVS responses suggest a vestibulospinal deficit in the SCI subjects. Significance GVS can be applied in incomplete SCI to supplement the neurological examination by revealing changes in vestibulospinal responses and impairment of postural stability.