Adult Hydrocephalus- Neurosurgery

Hydrocephalus (the word "hydro," meaning water, and "cephalus", referring to the head) is an abnormal buildup of fluid in the brain's cavities. The condition can be detected in people of any age.

In young and middle-aged adults, hydrocephalus is a distinct and frequently confusing condition. This differs significantly from hydrocephalus identified in infancy, early childhood, or adult-onset normal pressure hydrocephalus (NPH) found in older adults (usually 60 and older).

Both patients and medical professionals face various opportunities and obstacles in adults with hydrocephalus. The difficulty includes behavioral, emotional, and occupational concerns in addition to routine or specialized medical care.

Understanding Hydrocephalus

Hydrocephalus occurs when too much cerebrospinal fluid (CSF) accumulates in the ventricles (cavities) of the brain, which can increase the pressure inside the head. Although "water on the brain" is a common description of hydrocephalus, the "water" is actually CSF, the clear fluid that flows in and around the brain and spinal cord, cushioning them against injuries.

CSF performs three vital tasks: it protects the brain and spinal cord against mechanical shocks; it transports nutrients and wastes away from the brain; and it moves between the skull and spine to control pressure variations inside the brain.

The average rate of CSF production is approximately 20 mL per hour. One or more of the ventricles swell as CSF builds up when an injury or disease disrupts the CSF circulation. As a result, the pressure inside the brain may significantly rise because the adult skull is stiff and cannot expand.

Hydrocephalus In Adults: Causes And Types

Adults with hydrocephalus fall into the following four groups.

1. Adults With Newly Diagnosed Congenital Hydrocephalus

Congenital hydrocephalus is the term used to describe hydrocephalus that is present at birth. Even though it is a disorder present at birth, symptoms may not always appear until adolescence or maturity.

It is unclear how hydrocephalus can remain undiagnosed for an extended time before developing symptoms. Either the fluid gradually builds up to the point where it causes brain malfunction, or chronic static expansion of the fluid spaces results in a subtle and ongoing injury that eventually reduces the brain's capacity for compensation. These situations can be categorized as decompensated congenital hydrocephalus.

Sometimes a head computed tomography (CT) or magnetic resonance imaging (MRI) ordered for completely unrelated neurologic symptoms reveals asymptomatic hydrocephalus. For instance, clinicians are frequently taken aback when hydrocephalus is discovered on brain imaging tests for minor head injuries. The trauma in these cases had nothing to do with the hydrocephalus, which was present all along.

2. Adults Who Acquire Hydrocephalus

The type of hydrocephalus that appears at any point after birth is known as acquired hydrocephalus. Acquired hydrocephalus can be diagnosed in both adults and children. The most frequent causes include the following:

• Brain tumors
• Head injuries
• Meningitis or other infection of the brain or spinal cord
• Brain bleed (Intraventricular hemorrhage)

3. Adults Who Are Diagnosed And Treated In Childhood

Before shunts were commercially available to treat hydrocephalus, there was no widely used treatment for patients, and long-term outcomes were not good. Now that children with hydrocephalus are growing up and entering adulthood, they will require adult medical treatment.

Conversely, many individuals get brain imaging for dizziness or headaches when such symptoms are caused by unrelated diseases such as migraine or inner ear abnormalities. Likewise, hydrocephalus would have been detected if a scan had been done before symptoms appeared.

Congenital hydrocephalus is caused by a complex combination of environmental and genetic variables during fetal development. The following are the most common causes of congenital hydrocephalus:

• Spina bifida
• Brain malformations
• Aqueductal stenosis

4. Adults With Normal Pressure Hydrocephalus

Normal pressure hydrocephalus (NPH) occurs when fluid accumulation in or around the brain impairs brain function. It may affect various mental functions, including memory, thinking and concentration, movement, etc. NPH can sometimes be reversed, even though its symptoms closely resemble those of dementia.

Idiopathic NPH (iNPH) is the term used to describe cases of NPH in which the reason for the obstruction in the CSF absorptive pathways is not known. The term "secondary NPH" refers to situations where a cause is obvious (e.g., trauma, stroke, tumor, or meningitis).

The prevalence of NPH increases with age and is most common among people over 65. This condition typically manifests itself at the age of 70. The single factor that increases the likelihood of this illness is advancing age. The chances are the same regardless of an individual's race, gender, ethnicity, etc.

Symptoms Of Adult-Onset Hydrocephalus

The signs of hydrocephalus in young adults can resemble those of NPH in the elderly in some ways, but they are frequently far more subtle. Nevertheless, they can dramatically impact patients' lives, in the most severe cases making adults unable to work or having trouble navigating daily life.

Occasionally, signs of a midlife crisis or other psychological or emotional problems are dismissed as symptoms. However, the inability to operate at home and work can also impair relationships and employment when symptoms increase and the issue is left undetected.

Among the symptoms recorded are, but are not limited to:

• Nausea
• Chronic headaches
• Balance and coordination issues
• Unsteady walk or gait
• Difficulty focusing the eyes and vision problems
• Leg weakness
• Irritability
• Change in personality and behavior
• Short-term memory issues
• Seizures
• Drowsiness
• Fainting(syncope)

Symptoms of NPH

Typically, symptoms of NPH develop and worsen over three to six months. Hakim's triad refers to the three main symptoms of NPH. Between 50% and 75% of adults with NPH simultaneously exhibit all three symptoms. Hakim's triad includes the following three types of symptoms:

1. Gait issues
2. Cognitive difficulties
3. Urinary incontinence

Gait issues

When you struggle with walking-related movements, you have gait issues. These symptoms are the most frequently occurring of the three, present in about 80% to 95% of NPH patients. A significant distinction between NPH symptoms and the movement-related symptoms of Parkinson's is that the former typically exclusively affect the legs and feet.

NPH frequently results in the following gait-related symptoms:

You have difficulty getting your feet up: This gives the impression that you are walking with your feet stuck to the ground. The difficulty of elevating your feet is frequently described as similar to how magnets resist when you draw them away from a magnetic surface.

Your movements are unsteady and shorter: This gives the impression that you are shuffling your feet as you walk. As a result, you become more prone to falling, tripping, and stumbling.

You either stop or walk erratically: It looks like you cannot take a step or continue walking after you have begun. While walking, you might also pause or have difficulty making wide turns.

As you walk, you turn your toes outward: Unfortunately, this may also cause you to spread your feet apart and walk like a penguin, stepping from side to side.

Cognitive difficulties

Cognitive difficulties are the second important NPH symptom type. This symptom may manifest as, or even be the cause of, any of the following:

Physical and mental slowness: This is when someone exhibits signs of thinking more slowly than usual or moving more slowly than expected.

Poor executive performance: This causes people to struggle to control their emotions, ideas, and actions. This may manifest as issues with concentration and focus, as well as sluggish and erratic decision-making.

Memory issues: Individuals with memory issues tend to appear absent-minded or forgetful.

Emotional changes: Sometimes, people with NPH can appear lethargic or uninterested in activities they once found enjoyable.

Urinary incontinence

When you suffer urinary incontinence, you accidentally urinate because your bladder is out of control. Early on, this may lead you to have frequent urges to urinate or to experience sudden, unusually strong urges, or both.

Those who experience this symptom may feel ashamed if they experience a loss of control over their bladder. Some individuals do not seem bothered by or embarrassed by this, though. Not feeling ashamed or worried may also be caused by cognitive difficulties.

Diagnosing Hydrocephalus

Brain imaging methods, including CT, MRI, and a thorough clinical neurological evaluation during a medical visit, are used to make a diagnosis.

During a physical and neurological examination, a medical professional looks for visible signs and symptoms of the problem. In addition, they assess your reflexes, arm and leg muscle strength, and other senses like vision, hearing, and touch.

The doctor may also ask questions about your symptoms and medical history. Your medical history, present symptoms, and medical records can help the doctor diagnose NPH.

Adults frequently undergo more tests to diagnose the condition. These tests could consist of the following:

• Lumbar puncture
• Continuous lumbar CSF drainage
• Measurement of cerebrospinal fluid outflow resistance
• Intracranial pressure (ICP) monitoring
• Isotope cisternography

Moreover, your doctor may also recommend a neuropsychological evaluation. The specific clinical scenario, the medical team's preferences, and their collective experience can influence the decision about which test to order.

Listed below are the tests involved in the diagnosis. Not all the tests mentioned are essential to make a diagnosis.

CT Scan

A CT scan is a reliable procedure for identifying hydrocephalus and helping the treatment process. It is a sophisticated technology in which x-ray beams are sent through the patient's body, and the computer creates images of the internal structures.

The initial sign of hydrocephalus in an adult is frequently an unexpected enlargement of the ventricles, but this discovery is typically insufficient to move forward with surgical treatment. Keep in mind that hydrocephalus can either be compensated (non-progressing) or uncompensated (progressing) and that additional testing is frequently required.

It is potentially harmful to place a shunt in a person with compensated hydrocephalus, just as it is potentially harmful not to do so in a person with decompensated hydrocephalus.

MRI

Like a CT scan, an MRI is a diagnostic tool that creates brain images. However, MRI does not include the use of radiation or x-rays. Instead, MRI scans the patient's body using radio signals and a strong magnet.

The signals are then converted into images by a computer. MRI scans are painless and have no known adverse effects.

There are two types of MRI scans. The Single Shot Fast Spin Echo (also known as a "quick brain MRI"), which takes around three minutes and hardly ever needs sedation, is used to measure ventricular size. A complete MRI takes 30 to 60 minutes, and sedation may be necessary for those prone to claustrophobia or anxiety. This is beneficial as it reveals more minute details.

After analyzing the images, the radiologist will report  interpretations to the physician. It is occasionally necessary to perform both a contrast-enhanced and a non-enhanced MRI. For example, an MRI with the addition of a chemical agent boosts and improves the clarity of the MRI image, enabling the physician to search for subtle indicators of a tumor or persistent infection that might cause adult-onset hydrocephalus. This allows them to discern the need for extra therapy in addition to shunt surgery.

Prior to the procedure, a physician or technician will administer the dye agent either intravenously (IV) or directly into your arm. The MRI will then proceed normally.

Lumbar Puncture (Spinal Tap)

A lumbar puncture allows the analysis of the fluid and estimation of CSF pressure. Under local anesthesia, a tiny needle is inserted into the spinal fluid space at the lower back. A 50 ml sample of CSF is removed to check on any potential temporary relief of symptoms. Surgery is likely to be successful if the removal of CSF significantly reduces symptoms, even momentarily.

Nonetheless, the prospect of improvement with shunt surgery is not ruled out if there is no improvement after a lumbar puncture. It is common knowledge that many patients who show little to no improvement after the test nonetheless benefit from shunts.

This test is crucial if the reason for the hydrocephalus is not apparent. Occult infections or malignancies with CSF spread may be detected through culture and testing the CSF for fungal organisms or tuberculosis.

Lumbar Catheter

External lumbar drainage, often known as continuous lumbar drainage or lumbar catheter insertion, is a variation of lumbar puncture. A spinal needle is used to reach the spinal fluid space in the lower back, and the fluid is subsequently extracted via a catheter (thin, flexible tube).

The lumbar catheter enables the continuous removal of spinal fluid over several days and the more accurate observation of spinal fluid pressure over time. In addition, external lumbar drainage is a test that can mimic the physiological effects of a shunt procedure to simulate the effects that a shunt would have.

Individuals who significantly improve after spinal fluid draining can probably benefit from shunt surgery. A tiny percentage of patients who do not improve with lumbar drainage may still benefit from a shunt procedure. Hospitalization is necessary for lumbar catheter insertion.

Intracranial Pressure (ICP) Monitoring

ICP monitoring is a diagnostic technique enabling your doctors to evaluate whether your symptoms are brought on by high or low CSF pressure. This requires hospital admission.

To measure the ICP, your surgeon will create a tiny hole in the skull called a burr hole and insert a small pressure sensor into the brain or ventricles. Then, a tiny pressure-sensitive probe put through the skull during the exam directly detects the pressure within your brain.

Isotopic Cisternography

This involves inserting a radioactive isotope via a spinal tap into the lumbar subarachnoid region (lower back). This allows periodic scanning to measure the CSF absorption over time (up to 96 hours). The procedure helps to determine whether the isotope is absorbed over the brain's surface or is trapped inside the ventricles. Compared to CT or MRI, isotopic cisternography requires lumbar puncture and is much more complicated.

Even when it returns a "positive" result, a cisternogram test does not decisively predict whether a patient would respond to shunt surgery. The procedure has become less preferred for this reason. In addition, its effectiveness in treating adult hydrocephalus is unknown.

Neuropsychological Testing

The study of brain-behavior connections is known as neuropsychology. When a patient's main issues are thought, emotion, and behavior, a neuropsychological assessment can be a crucial addition to clinical work in making a diagnosis. An assessment can also assist doctors and family members in comprehending how hydrocephalus affects a patient's day-to-day functioning.

A detailed interview with the patient and one or more family members is usually part of a neuropsychological examination, which also closely examines studies and medical records. In addition, many tests are undertaken to evaluate different facets of cognitive function, such as executive function (the ability to plan, reason, and modulate behavior), attention, memory, language, and visual-spatial aptitude. The ultimate objective is to comprehend how structural and functional changes in the brain impact the patient's behavior.

Neuropsychological testing can help assess whether an adult patient with hydrocephalus would benefit from urgent surgical intervention or would instead benefit from watchful waiting. Also, the pattern of neuropsychological impairment can be used to identify whether a patient's cognitive symptoms are likely caused by another coexisting neurological illness or hydrocephalus.

Your primary care physician, a neurologist, and a neurosurgeon must join your medical team at this stage of the diagnostic process. Their involvement from the diagnostic stage onward is beneficial in interpreting test results, choosing individuals likely to benefit from shunting, and addressing the actual surgery, postoperative care, and patient expectations.

When Is Surgery Necessary?

There are many techniques to treat hydrocephalus. The problem area may be treated indirectly (by diverting the fluid to another site, generally to another bodily cavity) or directly (by addressing the cause of the CSF obstruction).

Indirect treatment is done by implanting a shunt to transfer extra CSF away from the brain. The CSF is usually diverted to the peritoneal cavity (the area surrounding the abdominal organs).

In some instances, two surgeries are carried out: one to reroute the CSF and one to eliminate the obstruction later on (e.g., a brain tumor). The shunt system is typically implanted once and stays in place throughout the patient's life, though subsequent surgeries to modify the shunt system may be required. The shunt system continuously diverts the CSF from the brain, maintaining the intracranial pressure within normal ranges.

Your doctor might advise an alternate procedure called an endoscopic third ventriculostomy (ETV).

An endoscope is gently inserted into one of the lateral ventricles of the brain through a small incision in the skull (burr hole). The neurosurgeon will then puncture the membrane of the third ventricle using the endoscope, which is equipped with a camera, as it descends into the ventricle. As a result, CSF now has a different route to go through the brain. No shunt is required.

What Is Recovery Like?

The condition of your nervous system will be assessed after surgery. If any neurological issues persist, rehabilitation may be necessary to further your improvement. However, the magnitude of the hydrocephalus-related damage already done to your brain and its capacity for healing can restrict your potential to recover.

As hydrocephalus is a chronic disorder, constant medical monitoring is necessary. Follow-up diagnostic exams like MRIs, CT scans, and X-rays can help diagnose whether the shunt is functioning appropriately. If you encounter any of the following postoperative symptoms, do not wait to call your doctor:

• Redness, pain, tenderness, or swelling of the skin along the length of the tube or incision
• Feeling irritable or sleepy
• Headache, nausea, vomiting, or double vision
• Abdominal pain
• Fever
• Returning neurological symptoms from before surgery

Prognosis

Adults with hydrocephalus who receive appropriate treatment can often reverse many symptoms, returning much of their cognitive and physical performance. With the proper treatment, many adults with hydrocephalus can have fulfilling lives.

The long-term implications of hydrocephalus might differ significantly between individuals because it is a complex disorder. The cause, specific symptoms, promptness of the diagnosis, and the patient's receptivity to treatment all affect the prognosis.

Other neurological conditions can affect the prognosis as well. For instance, it is widely known that Alzheimer's disease (AD), which is more relevant in cognitive dysfunction, can coexist with NPH in older adults.

Other types of neuropathology that impair gait, such as stroke and neurodegenerative illnesses, can also be essential considerations. Unfortunately, even when shunts are proven to be functional, some of these diagnoses have the potential to "swamp" the effects of hydrocephalus over time, causing symptoms to worsen.

Headaches, chronic pain, as well as behavioral, emotional, and employment-related concerns, are some typical medical issues. However, it is important to note that untreated progressive symptoms can become quite incapacitating and result in serious physical and cognitive loss. In addition, hydrocephalus-related complications can occasionally become fatal.

The interval between the beginning of symptoms and diagnosis seems to affect how well a treatment works. The degree of reversible versus permanent brain impairment brought on by hydrocephalus is another yet immeasurable element that influences the course of treatment. When there has not been any irreparable damage, treatment works best.

References:

• M Das J, Biagioni MC. Normal Pressure Hydrocephalus. [Updated 2022 Jun 27]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK542247/
• Koleva M, De Jesus O. Hydrocephalus. [Updated 2022 Jul 25]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK560875/
• Edwards, Richard J et al. “Chronic hydrocephalus in adults.” Brain pathology (Zurich, Switzerland) vol. 14,3 (2004): 325-36. doi:10.1111/j.1750-3639.2004.tb00072.x

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