Pathophysiology of lower urinary tract symptoms in aged men without bladder outlet obstruction

OBJECTIVE: To assess the pathophysiology of lower urinary tract symptoms (LUTS) in aged men without bladder outlet obstruction in a videourodynamic study. METHODS: In a videourodynamic study of 324 consecutive men with moderate to severe LUTS suggestive for bladder outlet obstruction, 112 were found to be urodynamically nonobstructed. International prostatic symptom score (IPSS), uroflowmetry and transrectal sonography of the prostate were assessed before videourodynamic study. The pressure flow expression and the obstructive parameters were compared between the 212 obstructed and 112 nonobstructed men. RESULTS: Of the 112 nonobstructed men investigated, 25 had a normal bladder and urethral trace (22.3%), 5 had detrusor instability (4.5%), 17 had a hypersensitive bladder and a normal urethra (15.2%), 3 had detrusor underactivity and a normal urethra (2.7%), while 61 were found to have a poorly relaxed external sphincter and low detrusor contractility (54.5%). Most of the patients in the normal and hypersensitive groups had normal voiding pressure and high flow (NPHF) tracings, whereas men with detrusor underactivity or a poorly relaxed external sphincter had normal voiding pressure and low flow (NPLF) tracings. Only the maximal flow rate and voided volume were significantly higher in patients with NPHF than in patients with NPLF tracings. However, both groups showed a significantly lower IPSS, less residual urine, and a smaller transition zone index than the obstructive group. After medical treatment, 78 patients (69.6%) had satisfactorily improved, 31 patients (27.6%) remained stationary, while 3 (2.7%) worsened. CONCLUSION: Nonobstructed men with LUTS have various pathophysiologies other than benign prostatic obstruction. In this study 54.5% of these patients had poorly relaxed external sphincter on videourodynamic study. Identification of the underlying pathology can not only prevent unnecessary prostate surgery but can also enable proper medical treatment to be selected.