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Baclofen-induced cough suppression in cervical spinal cord injury,☆☆,,★★

Presented in part at the Annual Conference of the American Paraplegia Society, September 9, 1999, Los Vegas, NV.
https://doi.org/10.1053/apmr.2000.5612Get rights and content

Abstract

Dicpinigaitis PV, Grimm DR, Lesser M. Baclofen-induced cough suppression in cervical spinal cord injury. Arch Phys Med Rehabil 2000;81:921-3. Objective: To determine the effect of the GABA-agonist baclofen on cough reflex sensitivity in subjects with cervical spinal cord injury (C-SCI). Baclofen has been shown to inhibit the cough reflex in able-bodied volunteers. Design: Prospective, nonrandomized control trial. Setting: Veterans Affairs medical center with large outpatient SCI population. Participants: Twelve adult males (11 outpatients) with C-SCI chronically maintained on oral baclofen for the treatment of muscle spasm. Intervention: Subjects underwent cough challenge testing with inhaled capsaicin. The concentrations (μM) of capsaicin inducing 2 or more (C2) and 5 or more (C5) coughs were determined. Mean values for log C2 and log C5 were compared with a control group of outpatients with C-SCI not receiving baclofen. Results: Subjects treated with baclofen had a significantly higher cough threshold (diminished cough reflex sensitivity) than control subjects. Mean (± standard error of the mean) values for log C2 in study subjects and controls were 1.28 ±.16 and.65 ±.15, respectively (p =.009). Mean values for log C5 in subjects receiving baclofen and in control subjects were 2.20 ±.22 and 1.43 ±.23, respectively (p =.024). Subjects and controls did not differ in terms of age, spirometric parameters, or duration of injury. Conclusions: The results suggest that chronic therapy with baclofen diminishes cough reflex sensitivity in subjects with C-SCI. The clinical significance of this finding remains to be elucidated. © 2000 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation

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Subjects

Twelve male subjects (11 outpatients) with mid-to-lower C-SCI, chronically maintained on baclofen for the relief of muscle spasm, were recruited for study, which was approved by the Institutional Review Board of the Veterans Affairs Medical Center, Bronx, New York. Subjects were without history of pulmonary disease or recent (within 1 month) symptoms of respiratory tract infection, seasonal allergies, postnasal drip, or gastroesophageal reflux. All subjects underwent annual, complete physical

Results

All subjects were able to perform baseline spirometry and capsaicin challenge studies adequately. The induction of 5 or more coughs was achieved in all subjects. Mean ( ± SEM) log C2 and log C5 values for study subjects and controls (fig 1) showed that subjects maintained on baclofen had significantly higher cough thresholds (decreased cough reflex sensitivity) than control subjects.

. Capsaicin cough challenge data in subjects treated with baclofen and control subjects: ○, mean log C5; ●, mean

Discussion

Our finding that chronic therapy with the GABA-B agonist baclofen inhibits the sensitivity of the cough reflex in subjects with C-SCI is consistent with findings of previous studies on the antitussive effect of baclofen in healthy volunteers,7 in patients with idiopathic cough,9 and in patients with cough from angiotensin-converting enzyme (ACE) inhibitors.10

Because few subjects were available, our study group of 12 subjects included 3 smokers, whereas the control group consisted entirely of

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Supported by the Eastern Paralyzed Veterans Association.

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No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the authors or upon any organization with which the authors are associated.

Reprint requests to Peter Dicpinigaitis, MD, Albert Einstein Hospital, 1825 Eastchester Rd, Bronx, NY 10461.

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a. Sigma Chemical Corp, 3050 Spruce St, St. Louis, MO 63103.

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b. Model 646; DeVilbiss Health Care, Inc, Somerset, PA.

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c. Koko DigiDoser; Pulmonary Data Service Instrumentation, Inc., 908 Main St, Louisville, CO 80027.

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