Overactive bladder (OAB) syndrome is a disorder characterized by abnormal electrical overstimulation of the detrusor muscle and the external urethral sphincter. Both these muscles’ contractions are controlled by the efficacy and coordination of their respective innervations. When these electrical commands become erratic, the bladder may lose its control to properly store and hold urine. The result is a form of incontinence and the main symptom of OAB is an urgent and irresistible desire to pass urine. Programmed and controlled Electrical stimulation is one of the treatment methods for OAB. Accompanying symptoms include:
- Abnormally high frequency of micturition
- The feeling of extreme urgency accompanied in some cases by pain.
The Bridley procedure has entrenched itself as the stimulating method of choice. Also known as the Finetech-Bridley sacral anterior root stimulator, it is implanted to promote the functions of the sacral nerves S2 to S4 which form the major nerves that control bladder emptying. The sacral nerve 3 supplies detrusor muscle innervation and forms the main target of the Bridley procedure for OAB treatment.
The posterior tibial nerve (PTN) is also used as a stimulation location. The PTN is a bundled nerve formed by fibers of the lumbar 5 (L5) to sacral 3 (S3) nerves. The PTN’s origin coincides with the location of the S2- S4 segment responsible for parasympathetic neural supply to the bladder. The common stimulator for PTN is the Stoller afferent nerve stimulator (SANS). The technique involves insertion of a 34G needle into the SP6 point (this is an acupuncture point referred to as the ‘spleen 6’. It is located on the medial lower part of the leg just above the medial malleolus) that is used in electroacupuncture procedures. Electrodes are then placed to the rear of the medial malleolus. The benefits of transcutaneous electrical nerve stimulation (TENS) are not taken advantage of if performed only once. Long-term application and outcomes differ and may be determined by:
- Intensity of stimulation
- Electrode positioning
- The clinical presentation of the patient.
- Goals of the treatment.
There is no overall standardized technique for performing TENS which is a problem in establishing exactly how this nerve stimulation works. The problem is further complicated by different available literature and research related to TENS. The diversity of its results vary, specifically:
- Stimulation measurements
- Site of stimulation
- Patient’s co-existing health conditions
- Presenting symptoms
- No long-term follow-up data
The relative subjectivity adds to the difficulty of determining which TENS method is the most effective technique. The current general opinion among TENS enthusiasts is that stimulation of S3 is probably the most beneficial.
Stimulation of PTN is also promising but more studies are needed to establish a true understanding of the mechanism behind the technique’s promissory potential.
The future of TENS rests on well-structured studies that involve standardized research methods including established protocols for stimulation.