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Towards a novel implantable closed-loop neuroprosthetic device to control the overactive bladder


S. Jezernik

Aalborg University, Denmark, Ph.D. Thesis done at Center for Sensory Motor Interaction, Supervisor: Prof. Thomas Sinkjaer; period 1996-1999;

The bladder overactivity can be classified as detrusor hyper-reflexia or detrusor instability. It can be caused e.g. by spinal cord injuries, suprapontine lesions, Parkinson's disease or hypersensitivity of the bladder receptors. Involuntary bladder contractions can cause incontinence and/or high bladder pressures endangering renal function. Because of the medical and social problems associated with bladder overactivity and incontinence, treatment is required. Currently available treatment modalities such as drugs and surgeries often fail or have severe side-effects. An alternative option to control bladder overactivity could be the use of neural control techniques. Recording and processing of neurographic (ENG) signals could be combined with electrical stimulation in an implantable closed-loop neuroprosthesis to: (1) detect overactive bladder contractions by recording sensory information originating from bladder afferents, (2) inhibit bladder contractions by electrical stimulation of bladder inhibitory pathways, (3) if necessary, determine bladder volume from electroneurographic recordings. Determination of the bladder volume would be beneficial in the cases of lost bladder sensation as for example in the complete spinal cord injuries. To examine the feasibility of such a neuroprosthesis, acute animal experiments were performed in pigs and cats. Nerve cuff electrodes were used to electrically stimulate the nerves and to record the ENG signals, since they can be successfully implanted around different peripheral nerves over long periods of time. Nerve cuff signals were recorded from the pelvic nerve and sacral nerve roots during passive bladder distensions and bladder contractions. The recordings were analyzed qualitatively and quantitatively, and the changes in the nerve activity recorded during the quasi-periodic bladder contractions were used to detect the onsets of the contractions. The nerve recordings enabled detection of the fast bladder pressure rises associated with the bladder contractions, but did not allow determination of the bladder volume. The onset of the bladder contraction could be detected fast enough to trigger bladder inhibition and prevent dangerous bladder pressure levels. Furthermore, we demonstrated that the electrical stimulation of the S1 dorsal root was able to terminate an ongoing bladder contraction in cat. In conclusion, the presented results demonstrate that it is possible to detect bladder contractions from nerve cuff recordings. It is furthermore shown that the detection of the overactive bladder contractions could be combined with bladder inhibition and new signal processing techniques in a novel closed-loop neuroprosthesis. Such an implantable neuroprosthetic device would present an alternative treatment for individuals suffering from bladder overactivity.


Type of Publication:

(03)Ph.D. Thesis

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% Autogenerated BibTeX entry
@PhDThesis { Xxx:2000:IFA_16,
    author={S. Jezernik},
    title={{Towards a novel implantable closed-loop neuroprosthetic
	  device to control the overactive bladder}},
    address={Aalborg University, Denmark},
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