Recording the evoked canine detrusor electromyogram

Abstract

With increasing interest in detrusor disorders and possible detrusor myopathies, a method for recording the detrusor electromyogram (detrusor‐EMG) would probably greatly assist the diagnosis of various bladder dysfunctions. Therefore, we investigated the electromyographic activity of the detrusor during sacral root stimulation and during spontaneous bladder contractions in six anesthetized dogs. In all experiments, a high correlation of detrusor‐EMG recordings with bladder contraction was observed. Analysis in the time domain and power spectrum analysis revealed the most clear correlation of detrusor‐EMG with intravesical pressure rise in a frequency band above 3 Hz. The spike duration was 100 to 250 ms with an amplitude of 100 to 500 μV. Low‐frequency activity below 1 Hz was mainly presumed to be artifacts due to fluid movement under the electrode. Our trials indicate that smooth muscle EMG recordings from the detrusor smooth musculature are possible. The exact physiological relevance of the signal in the sub‐Hertz domain (<1 Hz) is still uncertain. The presented animal model allows the pathophysiologic investigation of various pathologies of bladder dysfunction and detrusor myopathies. Neurourol. Urodynam. 18:687–695, 1999. © 1999 Wiley‐Liss, Inc.

Bladder electrical activity: the elusive electromyogram

“…Note increased electrical activity preceding intravesical pressure rise, most evident in the 3–100 Hz band. Reproduced from [28] by permission of Wiley‐Liss Inc.…”

“…In response, a further attempt by the German group [28] used low impedance Ag/AgCl electrodes implanted into the bladders of anaesthetized dogs. Detrusor contractions were evoked by sacral anterior root stimulation, and attempts made to correlate the evoked electrical signal with detrusor contractions.…”

“…Note increased electrical activity preceding intravesical pressure rise, most evident in the 3-100 Hz band. Reproduced from [28] by permission of Wiley-Liss Inc. In contrast to cholinergic neurotransmission, purinergic excitatory mechanisms in detrusor smooth muscle appear to be associated with transmembrane electrical currents [2,32,38,39].…”

Ein standardisiertes In-vivo-Modell zur Evaluierung anticholinerger Effekte auf die Blasenkontraktion, den Speichelfluss und auf das Elektromyogramm der Harnblase - A standardized Model for in vivo Investigations of Anticholinergic Effects on Bladder Function, Salivation and Electromyographic Characteristics of the Detrusor - - C. E. Alken-Preisarbeit 2000 -

“…Die Elektrostimulation der Sakralwurzeln resultiert in einer neurogenen Aktivierung der Myozyten des Detrusors und führt somit zu einer generalisierten und messbaren Blasenkontraktion. Während der stimulationsinduzierten Blasenkontraktion konnte eine Korrelation zwischen hochfrequenter Spikeaktivität im D-EMG und intravesikalem Druckanstieg nachgewiesen werden [16,17,20]. Analysen im Zeitbereich und im Leistungsdichtespektrum zeigen eine auffällige Korrelation von elektromyographischer Aktivität und intravesikalem Druckanstieg in einem Frequenzbereich oberhalb 3 Hz [20].…”