The management of detrusor instability.
Detrusor instability is a urodynamic diagnosis made when the detrusor is shown objectively to contract, spontaneously or on provocation, during the filling phase of a cystometrogram while the patient is attempting to inhibit micturition. It often is responsible for symptoms of urgency, frequency, nocturia, urge incontinence, and nocturnal enuresis, but is not synonymous with any of them. Furthermore, it may be responsible for urinary incontinence which appears to be simple stress incontinence, and should be excluded before an operation for genuine stress incontinence is undertaken. Patients with mixed incontinence should have their detrusor instability treated before an attempt at surgical correction of stress incontinence is made. A number of therapeutic options exist for the unstable bladder. The simplest is bladder drill. My own preference is to start patients on bladder drill in conjunction with oxybutynin chloride 5 mg orally three times daily, with the plan of weaning them off the medication if possible in 3-6 months. Propantheline bromide in dosages of 15-30 mg orally four times daily also appears to be effective. Imipramine, in dosages of 25-50 mg orally twice daily, or up to 75 or 100 mg orally at night also may be helpful, especially if the patient suffers from nocturia or nocturnal enuresis. The effects of imipramine appear to be additive to those of other drugs, and this makes it a useful adjunct in therapy. Emepronium bromide and flavoxate hydrochloride appear to be less useful pharmacologic agents. The expected addition within the next few years of terodiline hydrochloride to the drugs available in the United States is likely to improve significantly our ability to treat detrusor instability. The use of prostaglandin synthetase inhibitors in women with perimenstrual exacerbations of their symptoms may be useful on a case-by-case basis. Patients who do not experience improvement with behavioral intervention and pharmacologic treatment may be candidates for electric stimulation therapy or surgery. The efficacy of electric stimulation therapy is diminished in many cases by poor patient acceptance. The most effective surgical treatment for refractory detrusor instability appears to be augmentation cystoplasty, which should be attempted only by a trained reconstructive urologist, and which should be reserved for the most refractory and difficult cases.