What is Hydrocephalus?
Hydrocephalus is a condition that affects people of all ages. If you or a loved one has been diagnosed with hydrocephalus, you may be wondering what it is and what it means for your health. The following sections will explore the causes and symptoms of hydrocephalus, as well as how it is diagnosed and treated.
Hydrocephalus is Greek and translates to “hydro”(meaning water) and “cephalus” (meaning brain). Hydrocephalus is a condition characterised by excess accumulation of cerebrospinal fluid (CSF) in the skull cavity, which leads to increasing pressure on the brain. Hydrocephalus can occur at any point in a person's life, but it is typically observed in infants and individuals aged 60 years and above. The National Institute of National Institute of Neurological Disorders and Stroke (NINDS) estimates that roughly one to two out of every 1,000 babies born in the United States are affected by hydrocephalus. A significant proportion of these cases are typically detected before or at the time of childbirth, or during the early years of childhood.
CSF is a transparent and watery substance that occupies the ventricles (open spaces) in the brain and the area surrounding the brain and spinal cord known as the subarachnoid space. The ventricles inside the brain form a connected system of hollow spaces that contain CSF. CSF flows freely throughout the nervous system and serves the following roles: Firstly, it functions as a buffer to absorb shock for the brain and spinal cord. Secondly, it facilitates the transportation of nutrients to the brain and eliminates waste from it. Finally, it regulates pressure changes by circulating between the skull and spine. The build-up of CSF can cause pressure-related damage to the brain which is restricted within the bony skull.
Types of hydrocephalus
Hydrocephalus can be classified into two types based on fluid obstruction.1
- Communicating Hydrocephalus or Non-obstructive: This type occurs due to a block in the flow of CSF from one ventricle to another. Non-communicating Hydrocephalus commonly affects individuals over 50 years of age and develops gradually post-stroke or injury
- Hydrocephalus ex-vacuo: CSF circulates freely in this type of hydrocephalus. It can be divided further into normal pressure hydrocephalus (NPH) and hydrocephalus ex-vacuo. This also occurs due to brain injury or stroke but as a result of loss of brain tissue
Hydrocephalus can be further classified based on causal factors.
Present at birth, congenital hydrocephalus can be caused due to inherent genetic structural defects like aqueductal stenosis (the narrowing of the connections between the ventricles), or developmental conditions associated with neural tube defects like spina bifida (improper formation of the spinal cord) and encephalocele (brain protruding from skull). This type of hydrocephalus affects nearly one in 1,000 babies.
Acquired hydrocephalus occurs at birth or later, in the absence of a confounding factor. This is mainly caused by trauma or stroke leading to haemorrhage, infections, or obstruction in the passage due to tumours and cysts.
Signs and symptoms
The signs and symptoms of the condition can be manifested differently depending on the age of the patient. Vomiting is a common symptom of increased intracranial pressure in infants and young children, while loss of motor and cognitive functions such as walking or thinking may occur in adults.
Common signs and symptoms include:
- Nausea and vomiting
- Developmental and cognitive difficulties
- Drowsiness and irritability
- Urinary incontinence
The most prominent and visible sign of hydrocephalus is the abnormally large head size which is observed in infants.
In adults, psychological symptoms like mild dementia or memory loss can be observed.
Treatment of hydrocephalus is based on the causative factor. The condition can be treated directly using surgical means to remove the causal obstruction. However, the condition is commonly treated indirectly by diverting the excess fluid out of the ventricles using a ventriculoperitoneal shunt. Shunts are flexible tubes used to drain the excess CSF from the ventricles into the abdominal cavity. Individuals with a shunt should be monitored regularly for signs of complications and failures like the reappearance of hydrocephalus symptoms, fever, and abdominal pain.
Diagnosis of hydrocephalus involves detailed history and clinical evaluation, including intra-uterine and maternal history. A neurological examination, accompanied by tests such as a computed tomography scan (CT or CAT scan), magnetic resonance imaging (MRI), and intracranial pressure monitoring, confirms the diagnosis and narrows down the cause.
Congenital hydrocephalus can be associated with risk factors such as uterine infection, low folic acid uptake, alcohol consumption during pregnancy, multiparous pregnancy, and a family history of hydrocephalus. Acquired hydrocephalus can occur in individuals with brain tumours, or post-injury or stroke.3
Progression of hydrocephalus can lead to the following complications:
- Visual changes
- Cerebral herniation (movement of brain tissue)
- Septicemia (bloodstream infection)
- Walking and coordination disabilities
- Loss of bladder control
- Cognitive dysfunction
- Shunt-related complications and failure
- Peritonitis (inflammation of abdominal walls)
- How can hydrocephalus be prevented?
In most cases, hydrocephalus cannot be prevented, but prompt treatment can help manage the condition and prevent complications. Good antenatal care, with proper supplements, can help prevent the congenital development of hydrocephalus. Monitoring intracranial pressure post-trauma or stroke can reduce the risk of acquired hydrocephalus.
- How common is hydrocephalus?
The prevalence of hydrocephalus varies significantly by age group, with the paediatric population having an overall prevalence of 88 per 100,000 people and the adult population having an overall prevalence of 11 per 100,000 people.
The frequency of hydrocephalus is greater in Africa and South America. There are 1 to 32 infants with infantile hydrocephalus for every 10,000 births. The effects on both genders are typically equal.4
- When should I see a doctor?
If you or someone you know is experiencing symptoms of hydrocephalus, such as headaches, vomiting, and seizures it is important to see a healthcare professional as soon as possible. In infants, persistent changes in behaviour and delayed milestones can be a sign too. Speak to your midwife or doctor if you suspect your child may have hydrocephalus.
Hydrocephalus is a neurological condition caused by an excess build-up of CSF which exerts pressure on the brain and can cause various symptoms, such as headaches, nausea, vision problems, and difficulty walking. Hydrocephalus can be congenital (present at birth) or acquired later in life due to injury, infection, or other underlying medical conditions. Treatment typically involves surgically inserting a shunt to redirect the excess CSF to another part of the body where it can be absorbed.
- Azzam AM, Yehia A, Abd El-Bary TH, El-Sharkawy AM. Pathophysiology and Classification of hydrocephalus. Tobacco Regulatory Science (TRS). 2023 Jul 11:3381-403.
- Koleva M, De Jesus O. Hydrocephalus [Internet]. PubMed. Treasure Island (FL): StatPearls Publishing; 2020. Available from: https://www.ncbi.nlm.nih.gov/books/NBK560875/
- Millichap JG. Congenital Hydrocephalus Risk Factors. Pediatric Neurology Briefs. 2009 Feb 1;23(2):14.
- Van Landingham M, Nguyen TV, Roberts A, Parent AD, Zhang J. Risk factors of congenital hydrocephalus: a 10 year retrospective study. Journal of Neurology, Neurosurgery & Psychiatry. 2009 Feb 1;80(2):213-7.