Fowler’s syndrome was first described in 1985. This vesical dysfunction causes urinary retention in young women because of a disturbed interaction between the muscles needed for miction. The bladder can be emptied with a catheter (e.g. autocatheterism by the patient). All miction functions remain intact in such patients, with the exception of sphincter relaxation and vesical cervix relaxation, which are defective.
The treatment of choice is the catheter that the patient introduces herself to empty her bladder. It is essential to avoid the storage of large volumes (more than 500 ml) of residual urine. Sacral root neuromodulation is currently the only alternative to autocatheterism by the patient. The exact mode of action remains unexplained. It is thought that the emptying of the bladder is triggered by a contraction of the vesical muscles controlled by the CNS and paralleled by simultaneous inhibition of the sphincter.
Benefits and Risks
When compared to medullary stimulation, the LION sacral neuromodulation procedure has a disadvantage: the electrode is implanted through a surgical procedure requiring complete anaesthesia. However, its outcome appears to be more successful. Even though long-term effects of the LION procedure are not yet available, the first data indicate that the results are better than those obtained with medullary stimulation (success rates vary between 50 and 70%). The difference may be explained by the fact that in the LION procedure, neuromodulation does not target a single sacral root, but all the sacral roots important for bladder function.
The other advantage of the LION procedure is the direct contact between the electrode and the root. Indeed, the same level of control of the bladder function is achieved by a lower intensity of the electrical current in the LION procedure. In medullary stimulation and contrary to the LION technique, the electrode is introduced blindly through the skin. It may thus be positioned at some distance from the nerve and the current needed to produce the desired effect may be higher.