An overactive bladder (OAB) is a lower urinary tract symptom that is frequently found in stroke patients. In this excellent article written by Natsume, the occurrence of detrusor underactivity was considerably high in stroke patients (35% of male and 43% of female patients). In addition, detrusor overactivity with impaired contractility was found in 33% and 20% of male and female patients, respectively. Finally, OAB in patients with underactive detrusor appeared in 67% and 80% of male and female patients, respectively. It is thought that stroke is one of the common etiologic factors for OAB. Therefore, as shown in this article, diagnosis and treatment that depend on only a symptom diagnosis are accompanied by risk. It is important that indices such as residual urine volume should be added in dealing with OAB, even in the level of primary care physicians.

It is a fact that there are some shortcomings in this article. Intervals between stroke and urodynamic study were variable, and a reference to a change of detrusor activity with time was not made. In addition, causative diseases for stroke were various, and, the relationship between location of brain lesion and findings of urodynamic examination was not mentioned. An identification of a responsible lesion of detrusor underactivity should be thoroughly investigated at institutions carrying out many urodynamic examinations. From the viewpoint of real life practice, establishment of methods to diagnose a detrusor underactivity non-invasively and accurately would be expected.