**2. Dysfunctional voiding**

#### **2.1 Definition**

Dysfunctional voiding (DV) refers only to the disorder of the bladder emptying phase, and is characterized by intermittent contraction of the external urethral sphincter and/or PFMs during the voiding phase of a micturition cycle [4]. A typical finding is interuppted or staccato uroflowmetry curve with increased electromyography (EMG) pelvic floor muscle activity during urination.

The more severe form is referred to as Hinman syndrome by the author who first described it [5]. Other terms previously used for DV are detrusor-sphincter discoordination, non-neurogenic neurogenic bladder and occult neurogenic bladder. In the United States, the term "dysfunctional voiding" has been used for all types of voiding disorders, even bladder filling phase disorders. According to the ICCS standardization of terminology from 2016, DV refers exclusively to the disorder of the voiding phase [4]. It is thought to be the result of excessive PFM activity in an attempt to prevent urination that occurs due to uninhibited detrusor contractions in the early stage of bladder filling.

#### **2.2 Epidemiology**

Epidemiological data on DV are lacking. Dysfunctional voiding was found to occur in 4.2% of children referred for urinary incontinence [6]. In published studies, the prevalence was estimated to be between 5 and 25% and 32% [7, 8]. Dysfunctional voiding was observed in 65% of children aged 5-9 years with urinary tract infections, and in 23% of children who were urinary tract infections free [9]. It is evident that the criteria for including children in the studies were different, as well as the accuracy of their evaluation, which indicates the need to conduct new research to determine accurate data.

#### **2.3 Etiology**

Dysfunctional voiding was first observed in 1973 by Hinman and Baumann [5]. Hinman describes it as an acquired, reversible behavioral disorder that can be ameliorated by suggestion and changes in behavior. He defined it as a bad habit for special people in a bad family environment. Allen stated in 1977 that hyperactivity of a child is a typical sign and that psychological factors play a key role in at least 50% of the 21 children described [10]. He also points to the importance of stressful situations in the family, such as parental alcoholism, parental divorce and father dominance.

Contrary to these considerations, Van Gool points out that DV is not related to emotional or psychosocial problems, but is caused by delayed CNS maturation and external urethral sphincter dysfunction [11]. Hjalmas considers the importance of hereditary factors, as DV was observed in several members of the
