Article

Plastic changes in the human central nervous system can occur at
multiple levels, including circuits rostral to the lesion level in spinal cord
injury (SCI). GABA is the most important inhibitory neurotransmitter in the
brain. The authors hypothesized that one of the consequences of plasticity in SCI
patients could be enhancement of brainstem reflexes, and they investigated the
effect of continuous intrathecal baclofen (CITB) on such enhancement. METHODS:
The authors studied the early ipsilateral component R1 and the late component R2
of the blink reflex (BR), jaw jerk, masseter silent period (MSP), and auditory
startle response (ASR) in 9 SCI patients without baclofen and in 8 with CITB.
Nine healthy volunteers served as controls. RESULTS: The amplitude of R1 of BR
was significantly smaller in patients with CITB than in the other groups. The
area of R2 of BR and of the ASR recorded in the orbicularis oculi,
sternocleidomastoid, and biceps brachii muscles were significantly larger in SCI
patients without baclofen than in controls, whereas there was no difference
between patients with CITB and controls. The MSP magnitude was significantly
larger in patients with CITB as compared with those without baclofen. CONCLUSION:
The enhancement of brainstem reflexes in SCI patients may be due to plastic
changes at the brainstem level after SCI. The significant reduction in response
size in patients with CITB in comparison with patients without baclofen suggests
that the enhancement of brainstem reflexes may be due to decreased GABAergic
activity and that CITB is effective in reducing abnormal brainstem
hyperexcitability.

Langue : ANGLAIS