Article

Intrathecal baclofen (ITB) bolus injection effectively decreases
spinal excitability but the impact on lower limb muscle activation during gait
has not been thoroughly investigated. OBJECTIVE: Examine activation of medial
gastrocnemius (MG) and tibialis anterior (TA) muscles during gait before and
after ITB bolus injection in patients with resting hypertonia after acquired
brain injury. METHODS: Lower extremity Ashworth score, temporospatial gait
parameters, characteristics of the linear relationship between electromyogram
(EMG) and lengthening velocity (LV) in MG during stance, and the duration and
magnitude of TA-MG coactivation were assessed before and at 2, 4, and 6 hours
after a 50-microg ITB injection via lumbar puncture in 8 hemorrhagic stroke and
11 traumatic brain injury subjects. RESULTS: Temporospatial gait parameters did
not significantly differ across the evaluation points (P >/= .170). However,
Ashworth score (P < .001), frequency and gain of significant positive EMG-LV
slope (P </= .020), and duration of TA-MG coactivation
(P </= .013) significantly
decreased in the more-affected leg after ITB bolus. EMG changes were not
significantly different between patients who did (n = 10) and did not (n = 9)
increase gait speed after the injection. The timing of the largest decrease in
Ashworth score and the largest decrease in EMG parameters coincided in 36% of
cases, on average. CONCLUSIONS: ITB bolus injection alters the activation of MG
and TA during gait. However, the changes in muscle activation are not closely
related to the changes in gait speed or resting muscle hypertonia. The analysis
of ankle muscle activation during gait better characterizes the response to ITB
bolus injection than gait kinematics.
CI - (c) The Author(s) 2014.

Langue : ANGLAIS