Hydrocephalus is a medical condition where there is an excessive buildup of cerebrospinal fluid (CSF) within the brain. This fluid accumulation causes the brain’s internal cavities, the ventricles, to enlarge and exert pressure on surrounding brain tissues. Urinary incontinence is a common symptom experienced by individuals with hydrocephalus.
Understanding Hydrocephalus
Hydrocephalus develops when there is an imbalance in the production, circulation, or absorption of cerebrospinal fluid (CSF). CSF is a clear fluid that surrounds and cushions the brain and spinal cord. Normally, the body produces and reabsorbs CSF at a balanced rate, ensuring a constant volume. However, a blockage in CSF flow pathways or problems with its reabsorption can lead to its accumulation.
This accumulation causes the ventricles to widen, increasing pressure within the skull. Normal Pressure Hydrocephalus (NPH) is particularly relevant to urinary incontinence in adults, especially those over 60. In NPH, the ventricles enlarge, sometimes with minimal or no increase in overall intracranial pressure. This chronic pressure, even if seemingly normal, can still impact brain tissue.
How the Brain Controls Bladder Function
The normal control of urination is a complex process involving coordinated communication between the brain, spinal cord, and peripheral nerves. The bladder has two primary modes of operation: storage and emptying. During the storage phase, the bladder muscles remain relaxed, and the urethral sphincters stay contracted to hold urine. As the bladder fills, sensory nerves send signals to the spinal cord and specific brain regions, indicating increasing fullness.
When appropriate, the brain sends signals to initiate bladder emptying. Key brain areas involved include the frontal lobe and the brainstem, specifically the pontine micturition center (PMC). The frontal lobe plays a role in the conscious decision to urinate and in inhibiting urination until a suitable time and place. The PMC coordinates the contraction of the bladder muscles and the relaxation of the urethral sphincters, allowing urine to flow.
The Mechanism of Incontinence in Hydrocephalus
The increased CSF volume and pressure in hydrocephalus can disrupt the neural pathways that control bladder function, leading to urinary incontinence. The enlarged ventricles, particularly in Normal Pressure Hydrocephalus (NPH), can stretch, compress, or damage the surrounding brain tissue. This damage often affects the periventricular white matter, which consists of nerve fibers crucial for bladder control.
Nerve fibers connecting the frontal lobes to the brainstem and spinal cord, responsible for voluntary control and inhibition of urination, can be compromised. This disruption can manifest as problems with recognizing bladder fullness, an inability to suppress the urge to urinate, or poor coordination between bladder contraction and sphincter relaxation. In NPH, the stretching of periventricular sacral fibers of the corticospinal tract, near the lateral ventricles, is implicated in the loss of voluntary control over bladder contractions. This can result in an overactive bladder, leading to increased frequency and urgency of urination, or frank incontinence.
Addressing Urinary Incontinence in Hydrocephalus
Diagnosing urinary incontinence linked to hydrocephalus typically involves evaluating symptoms in conjunction with neuroimaging, such as MRI or CT scans, to visualize the enlarged ventricles and assess brain tissue. The primary approach to managing this symptom focuses on treating the underlying hydrocephalus. Surgical procedures, such as shunt placement, are common interventions.
A shunt is a medical device that diverts CSF from the brain to another part of the body, like the abdominal cavity, where it can be reabsorbed. Relieving pressure on brain tissues through shunting can often improve or even resolve urinary incontinence. If incontinence persists or is not fully resolved after addressing the hydrocephalus, other supportive measures may be considered, including bladder training exercises or medications to manage bladder overactivity.