Article

OBJECTIVE: To differentiate between dysautonomic and nondysautonomic subjects
with acquired brain injury by measuring sympathetic reactivity after a
nociceptive clinical procedure and to determine the utility of heart rate
variability as an indicator of sympathetic overresponsivity in dysautonomic
subjects. DESIGN: This case-controlled study recruited subjects with acquired
brain injury (mean, 5 yrs postinjury) attending a hospital-based outpatient
clinic, comprising seven dysautonomic subjects with traumatic brain injury, eight
nondysautonomic traumatic brain injury subjects, and 11 nondysautonomic subjects
with nontraumatic acquired brain injury. Sympathetic reactivity after nociceptive
stimuli (limb assessment and botulinum toxin injection for spasticity management)
was compared among groups. RESULTS: Sympathetic overactivity in dysautonomic
subjects was evident across all physiologic parameters, whereas nondysautonomic
subjects demonstrated limited reactivity. Heart rate variability measures of the
balance between sympathetic and parasympathetic cardiac control showed a
significant elevation in response to nociceptive stimuli, a response not observed
in either nondysautonomic group. This sympathetic overactivity showed a normalizing tendency with increasing time postinjury. CONCLUSIONS: This study
found persistent sympathetic overactivity in response to nociceptive stimuli in
dysautonomic subjects (mean, 5 yrs postinjury). This significantly extends the
duration over which such sympathetic overactivity has been quantified in this
group, contributing to the accumulating empirical evidence that dysautonomic
paroxysms result from sympathetic overresponsiveness. Given that sympathetic
overactivity has now been observed from day 7 through 5 yrs postinjury,
quantitative evaluation of patients for overresponsiveness to stimuli should be
added to current diagnostic procedures at all stages of recovery.

Langue : ANGLAIS