**2. Definitions and classification**

Children with significant lower urinary tract symptoms without associated neurological or anatomical abnormalities are considered to have non-neurogenic (idiopathic) lower urinary tract dysfunction (LUTD). It represents a disturbance of the lower urinary tract dynamics affecting urine storage or emptying and can simply be categorized into two types in children [2, 6]:

It says nothing about the storage phase. The term cannot be applied unless repeat uro‐ flow measurements show curves with a staccato pattern or unless verified by invasive urodynamic investigation [10]. Due to the abnormal contraction of the pelvic floor (pel‐ vic floor dysfunction), constipation is common in these children. Dysfunctional elimina‐ tion syndrome (DES) is often used to describe this disorder because this term accounts for the link between the difficulty in voiding and defecation caused by the abnormal contraction of the pelvic floor [3]. In recent studies, the rate of OAB in children with LUTD was reported variously as 58% and 71%. It has been suggested that the rate of DV

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Lazy bladder syndrome or myogenic failure is the loss of detrusor activity that requires the Valsalva maneuver to fully empty the bladder [2]. This condition is seen in about 7% of all dysfunctional voiders and typically occurs in females with a ratio of 5:1 to males [8]. Longterm fractionated voiding is thought to be the cause of this syndrome in which long voiding times result in loss of the normal detrusor function. Voiding is accomplished by increasing abdominal pressure to empty. Infrequent voids, large-volume post-void residuals with over‐ flow incontinence, and UTIs are the prevalent symptoms and signs. As a rule, urodynamic evaluation demonstrates a large-capacity, very compliant bladder; however, some of these

Hinman syndrome or nonneurogenic neurogenic bladder (NNNB) is often interchanged with occult neuropathic bladder and represents full decompensation of the voiding mecha‐ nism. Children will present with day and night-time incontinence, chronic UTIs, and chronic constipation. Urodynamic studies will often show uninhibited detrusor activity during fill‐ ing, high filling pressures, large post-void residual (PVR) volumes, and abnormal activity of the pelvic floor musculature during voiding. Imaging studies results are frequently abnor‐

Post-void dribbling is a disorder in which incontinence of urine occurs immediately after micturition. This syndrome is more common in female patients and is thought to be secon‐ dary to retained urine in the vagina that leaks after standing. Even though it is more likely to occur in obese girls it can also happen frequently in girls who are thin. This pattern can be seen on voiding cystourethrography. This can produce irritation of the labia, dysuria as the urine passes over the irritated skin, a reduced desire to void, incomplete emptying, and eventually recurrent UTI with its consequent changes in bladder function that further aggra‐ vate the clinical picture. Although these symptoms usually resolve with age and normal growth, the child may improve the symptoms more abruptly by facing backwards on the toilet with her body tilted forward and her legs straddling the toilet, or by manually spread‐

The aetiology of DV in otherwise healthy, neurologically intact children remains a matter of debate. In the absence of any neurologic or anatomic findings, the voiding patterns in DV

patients may also demonstrate a degree of detrusor overactivity [8].

mal with hydroureteronephrosis secondary to VUR being common [2].

ing the labia majora with fingers as she voids [8].

**3. Aetiology and pathogenesis**

is lower than that of OAB [11, 12].


Confusion can occur in identifying these syndromes as they may exist as a single entity or in combination and can be progressive.

Overactive bladder (OAB) syndrome, which is the most common pattern in children with LUTD, includes involuntary detrusor contractions and urethral instability. In children, OAB is the result of sudden and overwhelming urge to void that requires immediate urethral compression by the pelvic floor or by external manoeuvres such as the Vincent curtsy. This syndrome may also result in constipation from chronic pelvic musculature contraction [2]. OAB is thought to be due to a delay in acquisition of cortical inhibition over uninhibited de‐ trusor contractions in the course of achieving the mature voiding pattern of adulthood. Ab‐ normal overactivity of the pelvic floor musculature during voiding, instead of a complete relaxation, results in interrupted micturation [7]. The diagnosis of OAB syndrome can be made on examining the history of incontinence related to urgency, and does not require uro‐ dynamic evidence of uninhibited detrusor activity.

Functional urinary incontinence is the failure of the sphincteric mechanism to maintain con‐ tinence in anatomically normal children. True stress urinary incontinence in which there is an anatomic insufficiency of the sphincteric mechanism to hold urine in transmission of ab‐ dominal pressures to the bladder is rare in children [2].

Giggle incontinence is almost exclusively seen in girls and is characterized by large-vol‐ ume voiding that can occur with laughing. These patients have no voiding symptoms be‐ tween episodes and no other episodes of incontinence. The diagnosis is based on history alone and, unless there is a history of UTI, no further evaluation is needed. Although the aetiology is not clear, this may be a centrally mediated disorder similar to another disor‐ der, cataplexy, in which an emotional event causes muscle hypotonia. Accordingly, there is evidence that the central nervous system stimulant, methylphenidate, may be effective in prevention of these events [8].

Dysfunctional voiding is an abnormal contraction of the voluntary sphincter and pelvic floor during voiding that is thought to be an acquired disorder that may progress to complete loss of bladder function [9]. Voiding dysfunction has been used and is no lon‐ ger an acceptable term. This term describes malfunction during the voiding phase only. It says nothing about the storage phase. The term cannot be applied unless repeat uro‐ flow measurements show curves with a staccato pattern or unless verified by invasive urodynamic investigation [10]. Due to the abnormal contraction of the pelvic floor (pel‐ vic floor dysfunction), constipation is common in these children. Dysfunctional elimina‐ tion syndrome (DES) is often used to describe this disorder because this term accounts for the link between the difficulty in voiding and defecation caused by the abnormal contraction of the pelvic floor [3]. In recent studies, the rate of OAB in children with LUTD was reported variously as 58% and 71%. It has been suggested that the rate of DV is lower than that of OAB [11, 12].

Lazy bladder syndrome or myogenic failure is the loss of detrusor activity that requires the Valsalva maneuver to fully empty the bladder [2]. This condition is seen in about 7% of all dysfunctional voiders and typically occurs in females with a ratio of 5:1 to males [8]. Longterm fractionated voiding is thought to be the cause of this syndrome in which long voiding times result in loss of the normal detrusor function. Voiding is accomplished by increasing abdominal pressure to empty. Infrequent voids, large-volume post-void residuals with over‐ flow incontinence, and UTIs are the prevalent symptoms and signs. As a rule, urodynamic evaluation demonstrates a large-capacity, very compliant bladder; however, some of these patients may also demonstrate a degree of detrusor overactivity [8].

Hinman syndrome or nonneurogenic neurogenic bladder (NNNB) is often interchanged with occult neuropathic bladder and represents full decompensation of the voiding mecha‐ nism. Children will present with day and night-time incontinence, chronic UTIs, and chronic constipation. Urodynamic studies will often show uninhibited detrusor activity during fill‐ ing, high filling pressures, large post-void residual (PVR) volumes, and abnormal activity of the pelvic floor musculature during voiding. Imaging studies results are frequently abnor‐ mal with hydroureteronephrosis secondary to VUR being common [2].

Post-void dribbling is a disorder in which incontinence of urine occurs immediately after micturition. This syndrome is more common in female patients and is thought to be secon‐ dary to retained urine in the vagina that leaks after standing. Even though it is more likely to occur in obese girls it can also happen frequently in girls who are thin. This pattern can be seen on voiding cystourethrography. This can produce irritation of the labia, dysuria as the urine passes over the irritated skin, a reduced desire to void, incomplete emptying, and eventually recurrent UTI with its consequent changes in bladder function that further aggra‐ vate the clinical picture. Although these symptoms usually resolve with age and normal growth, the child may improve the symptoms more abruptly by facing backwards on the toilet with her body tilted forward and her legs straddling the toilet, or by manually spread‐ ing the labia majora with fingers as she voids [8].

## **3. Aetiology and pathogenesis**

**2. Definitions and classification**

90 Recent Advances in the Field of Urinary Tract Infections

combination and can be progressive.

dynamic evidence of uninhibited detrusor activity.

dominal pressures to the bladder is rare in children [2].

in prevention of these events [8].

types in children [2, 6]:

Children with significant lower urinary tract symptoms without associated neurological or anatomical abnormalities are considered to have non-neurogenic (idiopathic) lower urinary tract dysfunction (LUTD). It represents a disturbance of the lower urinary tract dynamics affecting urine storage or emptying and can simply be categorized into two

**1.** Problems related to the filling (storage) phase include overactive bladder (OAB) syn‐

**2.** Disturbances of the emptying (voiding) phase include dysfunctional voiding (DV), lazy

Confusion can occur in identifying these syndromes as they may exist as a single entity or in

Overactive bladder (OAB) syndrome, which is the most common pattern in children with LUTD, includes involuntary detrusor contractions and urethral instability. In children, OAB is the result of sudden and overwhelming urge to void that requires immediate urethral compression by the pelvic floor or by external manoeuvres such as the Vincent curtsy. This syndrome may also result in constipation from chronic pelvic musculature contraction [2]. OAB is thought to be due to a delay in acquisition of cortical inhibition over uninhibited de‐ trusor contractions in the course of achieving the mature voiding pattern of adulthood. Ab‐ normal overactivity of the pelvic floor musculature during voiding, instead of a complete relaxation, results in interrupted micturation [7]. The diagnosis of OAB syndrome can be made on examining the history of incontinence related to urgency, and does not require uro‐

Functional urinary incontinence is the failure of the sphincteric mechanism to maintain con‐ tinence in anatomically normal children. True stress urinary incontinence in which there is an anatomic insufficiency of the sphincteric mechanism to hold urine in transmission of ab‐

Giggle incontinence is almost exclusively seen in girls and is characterized by large-vol‐ ume voiding that can occur with laughing. These patients have no voiding symptoms be‐ tween episodes and no other episodes of incontinence. The diagnosis is based on history alone and, unless there is a history of UTI, no further evaluation is needed. Although the aetiology is not clear, this may be a centrally mediated disorder similar to another disor‐ der, cataplexy, in which an emotional event causes muscle hypotonia. Accordingly, there is evidence that the central nervous system stimulant, methylphenidate, may be effective

Dysfunctional voiding is an abnormal contraction of the voluntary sphincter and pelvic floor during voiding that is thought to be an acquired disorder that may progress to complete loss of bladder function [9]. Voiding dysfunction has been used and is no lon‐ ger an acceptable term. This term describes malfunction during the voiding phase only.

drome, functional urinary incontinence, and giggle incontinence.

bladder syndrome, Hinman syndrome, and post-void dribbling.

The aetiology of DV in otherwise healthy, neurologically intact children remains a matter of debate. In the absence of any neurologic or anatomic findings, the voiding patterns in DV are often believed to originate from behavioural issues. These behavioural traits may evolve from adverse events that occur around or after the time of toilet training and/or personal stresses [13]. Severe emotional stressors, such as sexual abuse mainly in girls, has been asso‐ ciated with DV, and should be considered in a child, especially a girl, who presents with new onset DV and no other identifiable etiologic factor [4, 5].

The association of facial expression with bladder function in this "Urofacial Syndrome" has been explained by the proximity of the cortical centres for the bladder and facial ex‐ pression in the brain. Presumably, this makes an association of abnormality between the

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A higher than expected association of idiopathic hypercalciuria, ranging from 21-30%, has been noted in children with DV syndromes. However, almost all responded to behavioural therapy, dietary modifications and anticholinergics and treatment specifically directed at hypercalciuria were needed in only two percent [26]. The reason for an association between hypercalciuria and DV remains unclear. The authors postulated that calcium microcrystalli‐ zation may cause injury to the urothelium and this could trigger a variety of urinary symp‐

It is probable that the entity DV is not homogenous and that there are several distinct aetiol‐ ogies that can lead to it. The end result is one of a dyssynergic sphincteric activity in the ab‐

There is not sufficient reported data on the relationship between the type of LUTD with UTI and VUR. The earliest studies of LUTD mostly dealt with either OAB or DV. This is a some‐ what artificial distinction, as these conditions are often combined and sometimes difficult to separate. For that reasons this association will be presented in LUTD children as a whole.

The association between LUTD and UTI has been established, though the causal relationship is not clear. Recurrent UTI has been shown in any studies to be higher in VUR patients with LUTD than in those without such dysfunction [3, 27, 28]. It has been demonstrated that ade‐ quate management of LUTD not only decreases the rate of UTI but also increases resolution of the VUR [27, 29]. Traditionally, recurrent UTI and pyelonephritis have been recognized as potential causes of permanent renal damage [30]. Current opinion is that VUR alone is not sufficient to cause UTI or renal damage. Holland et al. reported that girls with primary VUR followed up for 10 years, with no recurrent UTI, did not develop renal scars [31]. Linshaw showed that VUR does not threaten the kidney as long as UTI is promptly treated [32]. The results of these studies suggest that the association between VUR and UTI is necessary for renal damage to occur, mainly in situations of low detrusor pressure. However, VUR may predispose invasion of the renal parenchyma by bacteria. It has been reported that LUTD is an important risk factor for VUR and renal damage [33]. In addition, current studies have showed that increased intravesical pressure associated with LUTD is a primary factor for in‐ ducing reflux and renal damage [12, 34]. In patients who had UTI the presence of reflux in‐

VUR in LUTD is theorized to be not the result of a short mucosal tunnel, but to be the consequence of the high filling and voiding pressures. In patients with LUTD, uninhibit‐ ed detrusor contractions and voluntary constriction of the sphincter, causing a functional

two centres more likely.

toms including DV.

sence of a clearly defined neurological reason.

creased the rate of renal damage [12].

**4. Association of LUTD with UTI and VUR**

Detrusor overactivity as a component of DV may represent a persistence of the normal in‐ fant voiding pattern after toilet training. It may be that a mild delay in the maturation of the central nervous system disrupts the ability of these children to learn true voluntary control over the micturition reflex [5, 14]. An alternative theory to the development of the urge syn‐ drome hypothesizes that detrusor overactivity is caused by the transient obstruction that oc‐ curs with DV [15]. In support of the belief that the roots of DV may be grounded in behavioural issues or central nervous system developmental delays, an association has been demonstrated between DV and attention deficit hyperactivity disorder (ADHD). Higher rates of enuresis, urinary incontinence, constipation, and other voiding symptoms have been described in children with ADHD [16, 17].

As a result of studies of DV diagnosed in infancy, a congenital or genetic component to the disorder has also been postulated. Small series of infants with signs and symptoms consistent with NNNB syndromes have been reported [18, 19]. Furthermore, DV has been linked to the Ochoa syndrome, a genetic disorder with an autosomal recessive in‐ heritance pattern. The gene locus at chromosome 10q23-q24 is identified as the defective gene in Ochoa syndrome. It is postulated to be the possible gene locus of the NNNB de‐ scribed by Hinman and Allan [20]. This information casts doubt on the commonly held belief that disturbance of behaviour is the sole cause of NNNB because these findings are present at or near the time of birth.

At least some patients with DV represent occult neurogenic problems that will manifest provided these patients are followed longitudinally [21]. In all individuals with unex‐ plained severe DV, search for an unidentified neurological lesion must be made. A sub‐ tle neurological insult could present as DV. Such lesions may or may not be detectable with current imaging technologies. Routine magnetic resonance imaging in children with lower urinary tract problems without overt neurological signs and symptoms has a low yield of 7.5% but this may be improved by targeting children with abnormal cutaneous findings [22]. Tethered cord syndrome may be identified in some patients with subtle neurological signs and symptoms. Classical tethered cord has been diagnosed on the ba‐ sis of pathologically elongated conus or conus that lies below the L2 level. However, an‐ ecdotal successful outcomes following surgical division of the filum in children with apparently normally located cords suggest that the cord may sometimes be abnormally stretched without being at an abnormal location [23]. Such subtle lesions might also ex‐ plain the occasional presentation in infancy when the problem has its onset before toilet training has commenced [19]. Surgical division of the filum terminale in such patients is controversial but may yield improvements in bladder dysfunction [24].

Another possible indirect evidence for an unidentified neurological lesion in these pa‐ tients is the association of a peculiar facial expression in some children with DV [25]. The association of facial expression with bladder function in this "Urofacial Syndrome" has been explained by the proximity of the cortical centres for the bladder and facial ex‐ pression in the brain. Presumably, this makes an association of abnormality between the two centres more likely.

A higher than expected association of idiopathic hypercalciuria, ranging from 21-30%, has been noted in children with DV syndromes. However, almost all responded to behavioural therapy, dietary modifications and anticholinergics and treatment specifically directed at hypercalciuria were needed in only two percent [26]. The reason for an association between hypercalciuria and DV remains unclear. The authors postulated that calcium microcrystalli‐ zation may cause injury to the urothelium and this could trigger a variety of urinary symp‐ toms including DV.

It is probable that the entity DV is not homogenous and that there are several distinct aetiol‐ ogies that can lead to it. The end result is one of a dyssynergic sphincteric activity in the ab‐ sence of a clearly defined neurological reason.
