Congenital hydrocephalus

The cranial bones fuse by the end of the third year of life. For head enlargement to occur, hydrocephalus must occur before then. The causes are usually genetic but can also be acquired and usually occur within the first few months of life, which include 1) intraventricular matrix hemorrhages in premature infants, 2) infections, 3) type II Arnold-Chiari malformation, 4) aqueduct atresia and stenosis, and 5) Dandy-Walker malformation.

In newborns and toddlers with hydrocephalus, the head circumference is enlarged rapidly and soon surpasses the 97th%. Since the skull bones have not yet firmly joined together, bulging, firm anterior and posterior fontanelles may be present even when the patient is in an upright position.

The infant exhibits fretfulness, poor feeding, and frequent vomiting. As the hydrocephalus progresses, torpor sets in, and the infant shows lack of interest in his surroundings. Later on, the upper eyelids become retracted and the eyes are turned downwards (due to hydrocephalic pressure on the mesencephalic tegmentum and paralysis of upward gaze). Movements become weak and the arms may become tremulous. Papilledema is absent but there may be reduction of vision. The head becomes so enlarged that the child may eventually be bedridden. About 80-90% of fetuses or newborn infants with spina bifida - often associated with meningocele or myelomeningocele – develop hydrocephalus.

Acquired hydrocephalus

This condition is acquired as a consequence of CNS-infections, meningitis, brain tumors, head trauma, intracranial hemorrhage (subarachnoid or intraparenchymal) and is usually extremely painful for the patient.

Effects

Because hydrocephalus injures the brain, thought and behavior may be adversely affected. Learning disabilities are common among those with hydrocephalus, who tend to score better on verbal IQ than on performance IQ, which is thought to reflect the distribution of nerve damage to the brain. However, the severity of hydrocephalus differs considerably between individuals and some are of average or above average intelligence. Someone with hydrocephalus may have motivation and visual problems, problems with coordination, and may be clumsy. They may hit puberty earlier than the average child. About one in four develops epilepsy.

Because the problem resides inside the head, doctors rely heavily upon computer tomography scanning (CT scans), which may be used frequently to evaluate the condition of the disorder throughout the patient's life. Each CT scan exposes the patient to many times the level of x-ray radiation of a chest x-ray.

Treatment

Hydrocephalus treatment is surgical. It involves the placement of a ventricular catheter (a tube made of silastic), into the cerebral ventricles to bypass the flow obstruction/malfunctioning arachnoidal granulations and drain the excess fluid into other body cavities, from where it can be resorbed. Most shunts drain the fluid into the peritoneal cavity (ventriculo-peritoneal shunt), but alternative sites include the right atrium (ventriculo-atrial shunt), pleural cavity (ventriculo-pleural shunt), and gallbladder. A shunt system can also be placed in the lumbar space of the spine and have the CSF redirected to the peritoneal cavity (LP Shunt). An alternative treatment for obstructive hydrocephalus in selected patients is the endoscopic third ventriculostomy (ETV), whereby a surgically created opening in the floor of the third ventricle allows the CSF to flow directly to the basal cisterns, thereby shortcutting any obstruction, as in aqueductal stenosis. This may or may not be appropriate based on individual anatomy.

Shunt complications

Examples of possible complications include shunt malfunction, shunt failure, and shunt infection. Although a shunt generally works well, it may stop working if it disconnects, becomes blocked (clogged), infected, or it is outgrown. If this happens the cerebrospinal fluid will begin to accumulate again and a number of physical symptoms will develop (headaches, nausea, vomiting, photophobia/light sensitivity), some extremely serious, like seizures. The shunt failure rate is also relatively high (some sources site up to 45% chance of shunt failure in the first year following placement) and it is not uncommon for patients to have multiple shunt revisions within their lifetime. The diagnosis of cerebrospinal fluid buildup is complex and requires specialist expertise.

Another complication can occur when CSF drains more rapidly than it is produced by the choroid plexus, causing symptoms - listlessness, severe headaches, irritability, light sensitivity, sound sensitivity, nausea, vomiting, dizziness, vertigo, migraines, seizures, a change in personality, weakness in the arms or legs, excessive head growth (seen infants, children under age 2), strabismus, and double vision - to appear when the patient is vertical. If the patient lies down, the symptoms usually vanish in a short amount of time. A CT scan may or may not show any change in ventricle size, particularly if the patient has a history of slit-like ventricles. Difficulty in diagnosing overdrainage can make treatment of this complication particularly frustrating for patients and their families.

Resistance to traditional analgesic pharmacological therapy may also be sign of shunt overdrainage or failure. Diagnosis of the particular complication usually depends on when the symptoms appear.