ICS 1999, Denver
Informally discussed posters
Neurophysiology
EXPERIMENTAL STUDY FOR THE OBJECTIVATION OF BLADDER SENSIBILITY BY FREQUENCY ANALYSIS OF EEG ACTIVITY AND REGISTRATION OF EVOKED POTENTIALS

S. Bross, J.R. Scheepe, P.M. Braun, P. Alken, K.P. Junemann
Dept. Of Urology, University Hospital Mannheim, Germany

Neurological disases are often combined with disturbed or lost bladder sensibility. Aim of study was to develop a method that enables a statement whether intact afferences from the bladder to the brain exist or not. Another goal of this study was to evaluate different ways of selective and non-selective stimulation of bladder afferences

In 6 anesthetized foxhound dogs, bladder afferences were stimulated by bladder distension and by electrical stimulsion of the sacral posterior roots S2/S3. EEG activity was recordod before, during and after stimnlstion. In a second trial in 6 anesthetized foxhound dogs and 6 rabbits, cerebral evokod potentials were recorded by stimulation of the bladder afferences by bladder distension, by electrical stimulation of the bladder wall and by selective (Adelta and C-fibres) and non-selective (total nerve) stimulation of the sacal posterior roots.

The frequency analysis showed that maximal cerebral activity before stimulation ranged between 1 ad 5 Hz, whereas maximal activity during stimulation ranged above 8 Hz. After stimulation, the activity returned to the range between 1 and 5 Hz. The assesment of cortical evoked potentials showed that stimulation of the bladder wall by electrical stimulation and by bladder distension resulted in maximum cerebral responses with a frequency of more than 2.500 ms. During stimulation of the sacral roots by non-selective stimulation (total nerve), responses with a latency up to 800 ms and smaller responses from 3.500 up to 8.000 ms were observed. During selective stimulation of Adelta and C-fibres, the responses up to 800 ms were clearly reduced.

We conclude that the stimulation of bladder afferences results in obvious and reversible changes in EEG activity representing a higher vigilance. Selective stimulation of bladder afferences (bladder wall or Adelta and C-fibres) seems to be important for the assesment of cerebral evoked potentials. Furthermore, the registration of late potentials (up to 8.000 ms after beginning of stimulation) seems to be necessary in order to register all cerebral responses on stimulation. We believe that these methods enable objoctive assessment of bladder sensibility in this experimental setup. Further studies must be carried out before introduction clinical practice for the benefit of patients with disturbed or lost bladder sensibility.

(Source of funding: Ministry of Education and Rechearch Germany, Research Funds of the University Heidelberg/Mannheim.)