Hinman Syndrome

 Hinman Syndrome

Hinman Syndrome (HS) is a rare pediatric disorder characterized by bladder dysfunction that mimics neurogenic disease without evidence of neurologic damage. Normally, nerves carry messages between the brain, spinal cord and bladder to tell the bladder to either relax or contract.  In neurogenic bladder, however, this system does not work correctly, and the patient loses control of their bladder. Similarly, in HS, there is discoordination between the sympathetic nervous system (SNS) and parasympathetic nervous system (PNS), which can be thought of as the Yin-Yang control system of the bladder and bowel. The SNS and PNS play many roles in the body, including control of the bladder sphincter, which is a muscle that regulates the outflow of urine from the bladder. The SNS helps the sphincter contract to hold urine in, while the PNS relaxes the sphincter to allow the flow of urine out. In HS, the sphincter mistakenly closes when the bladder contracts, which increases bladder pressure. The continued discoordination between these two nervous systems over time causes children to develop disordered voiding (urination), which is commonly associated with behavioral and psychological conditions. This pattern can cause physical changes such as bladder wall thickening, outpouchings of the bladder wall (trabeculations) and back-up of urine into the kidneys (hydronephrosis). This dysfunctional voiding and incomplete bladder emptying can cause complications such as recurrent urinary tract infections (UTI), lack of control over urination (incontinence) and other symptoms of urinary tract deterioration. Hinman syndrome is thought to have a strong psychosocial component, and the worsening of the disease promotes further psychological and behavioral issues, which creates a vicious cycle .

SYMPTOMS

A common presentation of HS is urinary incontinence without symptoms of urgency or the sudden, uncontrollable need to urinate. This is similar to symptoms in patients with neurogenic bladder. Parents may notice their child not urinating as frequently or urinating too much. When asked, parents may report that the patient does not urinate; however, when they are requested or reminded to urinate, the child may empty their bladder. The patient will often report that they cannot feel the sensation of their bladder being full. Other signs include starting and stopping of the urine stream (intermittent stream), squeezing abdominal muscles to urinate and increased urine left in the bladder (residual volume) despite voiding multiple times. These can lead to increased pressure in the bladder due to increased urine volume and bladder muscle contraction. Recurrent UTIs, involuntary defecation (encopresis) and constipation can also be seen in patients with HS.

CAUSES

There continues to be disagreement in the scientific community about whether the disease is acquired or inherited. In other words, it is not clear whether parents pass this condition on to their children or if the disorder occurs by chance or because of environmental causes. Children under higher psychosocial stress are likely to have an increased risk. Children with behavioral issues or developmental delays will sometimes voluntarily contract the external sphincter (bladder outflow valve) to prevent urination, which can further aggravate this issue. A hallmark of HS is called “detrusor-external sphincter dyssynergia” which means the muscle that contracts the bladder (detrusor) and the external sphincter become disconnected. The nerve signals that usually trigger the bladder to contract and the sphincter to open for urine to flow out become unsynchronized and lead to urinary dysfunction. Similarly, disordered signals from the gastrointestinal tract can contribute to constipation and lack of control over bowel movements (fecal incontinence) in patients with HS.

AFFECTED POPULATIONS

The prevalence of HS is not known. The medical literature has described that HS occurs more frequently in males, but it has also been reported that females are more likely to develop complications from the disorder. This condition usually begins during childhood, but rarely, HS can occur during puberty, which is associated with increased severity.

DISORDERS WITH SIMILAR SYMPTOMS

Neurogenic bladder occurs because of a disruption of messages between the nervous system and bladder due to abnormalities in brain, spinal cord or nerves. Causes include tethered cord (anchoring of the spinal cord to nearby tissues), multiple sclerosis, diabetes mellitus, stroke, brain tumor or spinal cord injury. The presence of a sacral dimple is a typical telltale sign in children with tethered cord or lower spinal cord abnormalities. Symptoms include intermittent voiding, urinary retention and incontinence without an associated urge to void.

DIAGNOSIS

No formal diagnostic criteria have been established for Hinman syndrome. A diagnosis is suspected based upon identification of characteristic findings, a detailed patient and family history, a thorough clinical evaluation and voiding records. This condition is managed by pediatricians, nephrologists (kidney doctors) and urologists (surgical kidney and bladder doctors).

Based on the symptoms, the doctor will perform a thorough examination and may do a variety of urine tests, blood tests and scans . A dysfunctional voiding symptom score (DVSS) can be used to measure the severity of symptoms. Physical examination of the lower back, anus, genital region and legs is done to ensure normal anatomy and a functioning sensory system. Analysis of urine (urinalysis) is usually performed to rule out a UTI. Blood chemistry is also done to look for signs of any kidney damage. It is also important to perform an ultrasound scan of the kidneys and bladder to evaluate their structure and function, as well as check urine volume before and after voiding. Kidney and bladder ultrasound should be obtained in all patients with daytime accidents or in children who report an inability to feel the sensation of a full bladder. MRI of the lower spine should be considered to evaluate the anatomy of the spinal cord and to rule out the possibility of neurogenic bladder.

It is important to distinguish between the true neurogenic bladder and HS because true neurogenic bladder requires surgery, while HS does not. In patients with the above symptoms and a normal MRI scan of the brain and spinal cord, other clinical tests such as cystoscopy (scoping the bladder and taking pictures), voiding cystourethrogram (X-ray pictures of urinary tract using a dye) and video urodynamics (assess bladder and abdominal pressures and flow) should be considered.

STANDARD THERAPIES

Treatment and Prognosis

Early detection is vital to prevent the progression of HS because it can lead to kidney damage and kidney failure. Treatment options include pelvic floor physical therapy, biofeedback timed voiding and clean intermittent catheterization. Medication options include anticholinergics to decrease bladder contractions that lead to incontinence and alpha-blockers to facilitate bladder emptying. However, some scientists question how effective these medications are in children. Recent research suggests that other medications such as imipramine may help in the treatment of HS by reducing episodes of daytime and nighttime wetting. Treatment of accompanying issues such as constipation and recurrent UTIs can improve the quality of life. If these treatments are not successful, measures like Intravesical (within the bladder) botulinum toxin injections, sacral nerve modulation or reconstructive surgery of the bladder or urinary tract, or bladder diversion procedures may be helpful. In children with kidney damage, prompt evaluation and continuous follow-up with a nephrologist is indicated, as these children may need dialysis or kidney transplantation.

Type Of Doctor Department: Radiology