Article

The neural underpinnings of delayed automatic postural responses in people with
multiple sclerosis (PwMS) are unclear. We assessed whether white matter pathways
of two supraspinal regions
(the cortical proprioceptive Broadman's Area-3 ; and
the balance/locomotor-related pedunculopontine nucleus)
were related to delayed
postural muscle response latencies in response to external perturbations. 19 PwMS
(48.8+/-11.4years; EDSS=3.5 (range: 2-4)) and 12 healthy adults
(51.7+/-12.2years) underwent 20 discrete, backward translations of a support
surface. Onset latency of agonist (medial-gastrocnemius) and antagonist (tibialis
anterior) muscles were assessed. Diffusion tensor imaging assessed white-matter
integrity (i.e. radial diffusivity) of cortical proprioceptive and
balance/locomotor-related tracts. Latency of the tibialis anterior, but not
medial gastrocnemius was larger in PwMS than control subjects
(p=0.012 and 0.071,
respectively). Radial diffusivity of balance/locomotor tracts was higher (worse)
in PwMS than control subjects (p=0.004), and was significantly correlated with
tibialis (p=0.002), but not gastrocnemius (p=0.06) onset latency. Diffusivity of
cortical proprioceptive tracts was not correlated with muscle onset. Lesions in
supraspinal structures including the pedunculopontine nucleus balance/locomotor
network may contribute to delayed onset of postural muscle activity in PwMS,
contributing to balance deficits in PwMS.
CI - Published by Elsevier B.V.

Langue : ANGLAIS