Hydrocephalus: What Is It?
Hydrocephalus is a condition where there is too much cerebrospinal fluid in the head. It comes from the Greek words “hydro”, which means water, and “cephalus”, which means head. It is a component of several congenital health problems, but may be caused by head injuries, too. In some cases, the cause of hydrocephalus is unknown. It is often categorized into several types, depending on the cause.
Hydrocephalus is not a disease itself; it is considered a condition, the same way we view other conditions, such as diarrhea or fever. Therefore, treatment is focused on addressing its cause.
Hydrocephalus may cause the patient’s head to swell considerably to a larger-than-normal size. The effect is more prominent in babies whose skulls are not yet rigid and fixed. Hydrocephalus in babies can cause the baby’s head, from the forehead and crown to the back, to grow to an unusually large size that distorts facial features. In children and adults, hydrocephalus may not cause the head to grow in size, but the accumulation of fluid compresses the brain, causing painful headaches and other symptoms.
If left untreated, hydrocephalus may increase pressure inside the skull and compress the brain, resulting in serious symptoms. Treatment of hydrocephalus involves repairing or finding a way to remove or drain the excess cerebrospinal fluid in the head. It usually involves surgery and monitoring. Doctors pay attention to the pressure inside the head, called intracranial pressure. In some cases, treatment needs to be done right away.
Hydrocephalus also occurs in dogs, often in small breeds such as Chihuahuas, Cairn Terriers, Maltese, Pomeranians, Toy Poodles, Boston Terriers, and English Bulldogs. It often happens in the “runt” of the litter. As in humans, hydrocephalus in dogs is apparent soon after birth.
What Is Cerebrospinal Fluid?
The accumulation of cerebrospinal fluid causes hydrocephalus. Cerebrospinal fluid is a clear, colorless fluid surrounding the brain and spinal cord. Cerebrospinal fluid has several essential functions: it gives buoyancy to the brain, which prevents it from collapsing under its own weight; it cushions the brain against blows and shocks; when pressure inside the brain rises for any reason, cerebrospinal fluid production may go down to compensate and prevent problems in blood circulation; it allows for the transfer of nutrients, electrolytes, and hormones between the brain cells; and it diffuses metabolic wastes produced by brain cells.
The functions of cerebrospinal fluid are so essential that it is continually produced and reabsorbed. To give an idea of how much cerebrospinal fluid is produced, the turnover rate of production and reabsorption is three to four times a day. Therefore, any blockage or damage to the part of the head involved in reabsorption of cerebrospinal fluid immediately causes problems, like hydrocephalus.
What Is Congenital Hydrocephalus?
Congenital hydrocephalus is probably the most known type of hydrocephalus. It starts at birth and can be caused by genetics or events or injuries during fetal development, resulting in malformations or abnormalities in the brain. Untreated hydrocephalus can progress and cause death.
The size of the head in babies with congenital hydrocephalus may be apparent soon after birth. The accumulated fluid puts pressure on the brain, causing a variety of troubling symptoms. Some of the hydrocephalus symptoms in babies include irritability, fussiness, poor feeding, and frequent vomiting. As the head grows in size, the infant gradually becomes more lethargic and loses interest in its surroundings. Later, the eyelids retract, the eyes turn downwards, and body movements become weak. The infant’s head grows so large compared to its body proportions that the child eventually becomes bedridden. Some hydrocephalus cases also have other congenital problems, such as spina bifida.
Congenital hydrocephalus requires immediate evaluation by a specialist to determine the cause of the fluid buildup and the best way to place a shunt. Usually, treatment for hydrocephalus is surgery, where a shunt is placed inside the head to drain excess cerebrospinal fluid. Placement of the shunt prevents the head from growing further and eases pressure on the brain.
Unfortunately, shunt placement surgery has a significantly high failure rate–as many as 50% of patients require another surgery within two years. The shunt may fail by moving out of place, becoming blocked, or the site may become infected. The shunt may also fail by draining too much or too little cerebrospinal fluid. Surgery is needed to put the shunt back into place, called shunt revision.
Many patients require several surgeries for shunt revisions. In babies, urgent surgery can prevent brain damage caused by hydrocephalus.
What Is Normal Pressure Hydrocephalus?
Normal pressure hydrocephalus tends to occur in adults and is distinct from other types of hydrocephalus. In it, the space or void inside the head is significantly enlarged due to an increased volume of cerebrospinal fluid, however, readings or measurements of intracranial pressure remain normal or even low. It is somewhat rare compared to other types of hydrocephalus.
Normal pressure hydrocephalus symptoms include abnormal gait (shuffling or broad), urine incontinence, and dementia. The symptoms can be easily mistaken for Parkinson’s disease, but a test through administration of carbidopa-levodopa will identify the difference; if you have Parkinson’s disease, symptoms should improve. The doctor diagnoses the condition through imaging, often using either a computerized tomography (CT) scan or magnetic resonance imaging (MRI), which will immediately show the enlarged fluid-filled spaces in the brain.
The condition can be caused by head injuries, meningitis, tumors in the central nervous system, or bleeding between the membranes surrounding the brain (subarachnoid hemorrhage). Some individuals who were born with congenital hydrocephalus and left it untreated may have normal pressure hydrocephalus by the time they reach adulthood.
The treatment for normal pressure hydrocephalus is usually surgery. Again, a shunt is implanted to evacuate excess cerebrospinal fluid out of the head. However, it is not always successful in some patients whose source of blockage or fluid accumulation is poorly identified. Doctors will perform neuropsychological exams before and after the procedure. As is the case with most hydrocephalus cases, not all patients experience success with surgery.
In babies, hydrocephalus is confirmed by physically examining the head. The doctor will gather and examine symptoms to determine other congenital or health problems.
Imaging studies are important for diagnosing hydrocephalus in both adults and babies. MRI and CT scans are used to determine the cause of fluid buildup and where best to implant the shunt, as well as determine other congenital problems.
In some cases, the doctor may ask for a lumbar puncture, a procedure where cerebrospinal fluid is extracted from the bottom of the spine and assessed in the laboratory. A lumbar puncture is needed if there is suspected bleeding in the brain or possible meningitis. In addition, doctors will perform a neuropsychiatric evaluation to check the functioning of different parts of the central nervous system.
Surgery to Treat Hydrocephalus
Treating hydrocephalus requires surgery and is usually done by implanting a shunt to drain excess cerebrospinal fluid. The shunt is a thin, slender tube implanted in the head to evacuate some of the cerebrospinal fluid, and the other end is implanted on other areas of the body where the fluid can be reabsorbed. Once the production and absorption rate of cerebrospinal fluid is balanced, hydrocephalus is considered “compensated.”
The incisions are usually made behind the ear or the top or back of the head, and another is made in the neck or belly. Through the shunt, excess cerebrospinal fluid is channeled into places where it is reabsorbed again in the body. Those places may include the peritoneal cavity, the right atrium of the heart, or the pleural cavity.
There are several types of shunts available. Some of the shunts have one-way valves, anti-siphon mechanisms to counter over-drainage of fluid when standing up, and external access to determine the pressure of the cerebrospinal fluid. Some designs have chambers where the doctor can retrieve samples of cerebrospinal fluid, or inject medicines or dyes. Some shunts have connectors that allow surgeons to make custom-made shunts. There are shunt designs that are externally adjustable, so there is no need for surgery; doctors adjust these shunts by using strong magnetic fields.
Why Do Shunts Fail?
Shunt failure is a common occurrence in patients that, in most cases, can only be corrected by another major surgery. There are many causes of shunt failure: blood, organ tissue, clots, or bacteria may block the shunt; the area where the shunt is placed may become infected, necessitating the removal of the shunt and implantation of a new one; the shunt may also not work properly by draining too much or too little cerebrospinal fluid, leaving the hydrocephalus untreated.
Certain hydrocephalus cases, termed multiloculated hydrocephalus, arise when some of the cerebrospinal fluid occurs in other ventricles (areas of the brain that produce the fluid) that are not in communication with the main fluid pocket.
Obviously, a single shunt is not enough to treat multiloculated hydrocephalus. To treat it, doctors have to perform another surgery to place another shunt, or create an opening in the skull, to remove excess fluid.
Complications after shunt surgery are common and should be reported to the doctor right away. Premature babies and babies with other health conditions are at the most risk.
Babies may not be able to move or lift their head after surgery, so make sure to support the head when the child is rolling over or sitting. It will become less of a problem as soon as the baby’s body grows into proportion.
Infection of the shunt produces signs and symptoms including:
- Redness along the shunt
- Difficulty breathing
- Abdominal pain
- In babies, fussiness
Below are some signs and symptoms that require urgent medical care:
- Fading or loss of consciousness
- In babies, becoming more tired than usual
- Fever at or higher than 101°F (38.3°C)
- Abdominal pain or tenderness
- Stiff neck
- Lack of appetite, or not feeding in babies
- Appearance of veins in the head or scalp
- Fussiness in babies
- Any redness, swelling, pus discharge, or bleeding from the incision
- Repeated vomiting, or projectile vomiting
- High-pitched cry in babies
- Looking paler
- Head becoming larger
- Bulging fontanels
- Swelling around the shunt valve
What to Expect After Surgery
Patients require monitoring after surgery. Doctors will keep a close watch on the intracranial pressure and monitor for symptoms of complications. You, or the baby, may have to stay in the hospital for several days.
After the surgery, the patient has to lie flat in bed for twenty-four hours. The stitches or staples used to close the skin can be removed after a week or two. While the stitches or staples are present, the baby’s head should not be showered or shampooed; a sponge bath should be used to bath the child. The area where the shunt is visible or palpable should not be pushed.
In adults, incision areas should be washed with soap and clean water only. Pat them dry. Keep them clean and dry. If these areas weep or rub against clothing, you can cover them with gauze.
Make sure to take prescribed medicines as directed. In adults taking medications such as aspirin, clopidogrel, or warfarin, these medicines must be stopped several days or weeks before surgery. The doctor will say when to start them again. Follow the doctor’s orders for taking medications, especially antibiotics. Do not take any other medicine or change doses without doctor’s orders.
If there are no other problems or complications, unless the doctor says otherwise, babies can be held and carried normally. The risk of infection is highest within three months after the surgery, so you will have to visit the doctor regularly during that period.
The prognosis of surgical treatment for hydrocephalus is difficult to predict. Prognosis is poorer if the baby has complications, other medical problems, or if surgery is performed too late.