External anal sphincter contraction during cough: not a simple spinal reflex.
OBJECTIVE
To assess whether the anal contraction during voluntary coughing is a simple spinal reflex-mediated activity or not. To address this question we studied the external intercostal (EIC) muscle activity and external anal sphincter (EAS) response to cough.


METHODS
Electromyographic recordings were made from pre-gelled disposable surface electrodes. EAS electromyographic recordings were made from the EAS of the pelvic floor in 15 continent women all suffering from urgency and/or frequency without urge or stress urinary incontinence, and referred for urodynamic investigation. Electromyographic signal was immediately integrated (EMGi). The abdominal pressure was recorded with bladder and rectal pressure. EAS EMGi was recorded during successive voluntary cough. In three women, we have also recorded EIC EMGi activity since it is synchronous with diaphragmatic EMG activity during cough initiation.


RESULTS
In all subjects, EAS EMGi activity precedes the onset of the abdominal pressure increase. The mean latency of EAS EMGi was 615 msec (+/-278). In the three subjects whose EMGi activity was recorded both on EAS and EIC, the onset of EAS EMGi activity occurred before the EIC EMGi activity (latency ranging from 40 to 780 msec) and before the increase in the abdominal pressure.


CONCLUSIONS
The present study suggests that during coughing, EAS EMG activity increases before external intercostal muscle EMGi activity. The contraction of the EAS preceding the activation of muscles involved in coughing indicates that this response is not a result of a simple spinal reflex, but more likely the result of a more intricate reflex involving complex integrative centers.
Deffieux
Xavier
X
Department of Neurologic Rehabilitation, Urodynamic and Neurophysiology Laboratory, Rothschild Hospital, Assistance Publique-Hopitaux de Paris, Paris Cedex, France. x.deffieux@free.fr
Raibaut
Patrick
P
Rene-Corail
Patrick
P
Katz
Rose
R
Perrigot
Michel
M
Ismael
Samer Sheikh
SS
Thoumie
Philippe
P
Amarenco
Gérard
G
D000005:Abdomen / Q000503:physiopathology; D000328:Adult; D000368:Aged; D001003:Anal Canal / Q000503:physiopathology*; D003371:Cough / Q000503:physiopathology*; D004576:Electromyography; D005260:Female; D006801:Humans; D007366:Intercostal Muscles / Q000503:physiopathology; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology; D011312:Pressure; D012023:Reflex, Monosynaptic / Q000502:physiology*