Hydrocephalus – Disorder in the Circulation of the Cerebrospinal Fluid (CSF)
Treatment of hydrocephalus in breastfed infants and children, in adults or normal pressure hydrocephalus; arachnoid cysts and fistulas with fluid.
There are many ways that CSF can be lost: mastoid cells, sphenoidal sinus (post-surgical or empty sella syndrome), lamina cribrosa, frontal sinuses, fossa of Rosenmüller, an opening in the lateral craniopharyngeal canal and the internal auditory canal. Most fistulas are post-traumatic or post-surgical but some are spontaneous with no trigger cause. Spontaneous fistulas are usually progressive and intermittent at the start, and can be confused with allergic rhinitis. The diagnosis is usually difficult at the start due to the low amount of CSF and its lack of continuity. Pneumocephalus is not common.
The best choice of test is a ‘cisternotomography’ CT scan with water-soluble contrast agents, 90% of cases are successfully diagnosed using this technique.
An MRI scan hardly ever helps in diagnosing the condition, only if the CT shows a lesion which could be a skull base tumor which at times may cause a CSF fistula.
Regarding treatment, prophylaxis antibiotics are controversial since there is no study proving reduced incidence or morbidity in patients being treated with them. There is also a risk of creating new strains of bacteria.
Placing a continuous lumbar drain is the initial recommended treatment for 1 week. If it is not controlled, surgical intervention is then proposed as a treatment through craniotomy to seal the fistula provided that the CSF leak is located.
There are two main types of hydrocephalus:
Obstructive- This is caused by obstruction in the circulation of CSF in the ventricular system.
Non-obstructive- Caused by a lack of reabsorption in the arachnoidal granulation or hyperproduction of CSF. There is an independently valued entity known as normal pressure hydrocephalus –
The best choice of diagnostic method is a CT scan although an MRI scan can also be helpful in classifying hydrocephalus. The causes of hydrocephalus can be categorised as below:
- Congenital: associated with mielomeningocele, associated with Chiari malformation, primary stenosis of the Sylvian aqueduct, Dandy-Walker malformation, or strange disorders associated with the X chromosome
- Acquired: infectious (after meningitis, meningoencephalitis, abscess), post-haemorrhage, space occupying lesions (vascular or tumour), medullar tumours or post-surgical (previous neurosurgical intervention).
The most important differential diagnosis of hydrocephalus is: 1. Cerebral (many people show enlarged ventricles as a result of cerebral atrophy. That is to say that rather than there being a dilation, there is a ‘lack of brain’). 2. Hydranencephaly (complete or almost complete lack of the brain’s cerebral hemispheres), 3. Agenesis of the corpus callosum, 4. Septo-optic dysplasia.
The symptoms and signs of hydrocephalus depend on the age of the patient rather than the fusion of the sutures.
- Children with open sutures: increase in head-circumference irritability, poor control of the head, tense fontanelle, sixth cranial nerve palsy, reduced vertical gaze, and hyperactive reflexes.
- Children with fused sutures and adults: progressive headache, papilledema, nausea, vomiting and decrease in level of consciousness. It is important to consider that in some patients the hydrocephalus starts very quickly and the symptoms come in a matter of days or, at most, weeks; this is followed by decreasing levels of consciousness. Meanwhile, other patients’ symptoms develop over months or years with a much slower progression.
Treatment for hydrocephalus is fundamentally surgical although on some occasions we can try medical treatment using diuretics which is palliative up until surgical treatment begins. Not all patients are operated on as sometimes the cause of the hydrocephafalus is treated (vascular lesion, tumour, etc). Treatment is based on the following options:
- Cure the root cause of the hydrocephalus.
- Endoscopic third ventriculostomy. in general ventriculostomies is not advisable in communicating hydrocephalus. The general index of good results is around 60%, with the Sylvian aqueductal stenosis generating better results.
- Derivation of the CSF via ventricular derivation which can be carried out mainly in the abdomen (peritonea) sometimes other areas can be treated (heart, pleura).
Normal Pressure Hydrocephalus
This is a separate entity to the aforementioned hydrocephalus and is found in elderly people. The symptoms, which were originally described by Hakim and Adams in 1965, are typically dementia, gait disorders and sphincter control disorders. This entity typically causes normal CSF pressure in the lumbar region (due to this fact, it is currently being debated as to whether this entity is truly hydrocephalus, since there are no pressure changes throughout the course of the day). It is found in people over the age of 60, although there are cases in people under this age. It is considered idiopathic but in a number of important cases a trigger cause is detected which may have caused the hydrocephalus but which has remained latent up until the symptoms begin.
The main causes of hydrocephalus found in these patients are:
- Subarachnoid hemorrhage
- Cranioencephallic Trauma
- Neurosurgical intervention
Typical symptoms are: Gait irregularities: the patient takes short steps, wide-based gait (open legs) and they seem to be stuck to the ground.
Dementia: Characterised by memory disorder and bradyphrenia. It is very important as it is one of the few causes of dementia which can be treated.
Urinary incontinence: The patient does not have time to get to the toilet, although many times they are not conscious of the problem
It is important to note that diagnosis can be difficult on occasions, especially when the clinic is not fully established. The imaging tests (CT and MRI) must show the presence of ventricular dilation in order to achieve a diagnosis of normal pressure hydrocephalus. It is important to remember that sometimes cerebral atrophy (present in other illnesses leading to dementia) is difficult to differentiate from actual ventricular dilation. Other tests are performed on these patients to reach an accurate diagnosis of the illness, always taking into account the limitations of any of the tests in reaching an accurate diagnosis of the illness:
Tap test (evacuating lumbar puncture): This is used to perform a CSF evacuation (20-30 cc) and wait for the clinical evolution of the patients, so those who improve following the evacuation should be better after a tap is put in place. Similarly, patients whose CSF pressure is under 180 mmH2O are identified (if the pressure is higher than this, it is not considered normal pressure hydrocephalus).
Monitoring intracranial pressure: Patients whose pressure is being monitored, show that it is not really a case of ‘low pressure’ as there are patients of pressure of over 270 mmH2O. Those who show B waves are those who respond best.
Continuous lumbar drainage: On occasions a tap is put in place for a number days to evacuate CSF and this helps to evaluate the clinical evaluation.
Isotopic cisternography: the validity of this test is currently under debate.
The treatment for this condition is a ventriculoperitoneal shunt. Sometimes the clinical result is very good, although it should be considered that patients in this age range may have multiple illnesses which can cause similar symptoms.