Here I have given a brief overview of two important clinical manifestations. One affects the brain meninges (meningitis) and the other involves the brain ventricular system (hydrocephalus).

Hydrocephalushydrocephalus-scan.jpg


Hydrocephalus is an abnormal increase in the CSF volume within the ventricular system of the brain, which usually results in an increase in intracranial pressure.

This may occur due to :
  • a blockage interrupting the flow of CSF
The most common site for a blockage is the cerebral aqueduct. This aqueductal stenosis can be congenital or caused by a tumour. As the ventricles continue to produce CSF distention of the lateral and third ventricles occur. If the blockage is at the intrerventricular foramen, the drainage of CSF will only be blocked at the lateral ventricle on the same side. Inflammatory exudate due to meningitis can also interrupt the flow of CSF by blocking the subarachoid space and causing distention of the ventricular system.
  • too much CSF being produced
Can occur due to CSF- secreting tumour of the choroid plexus. This is a rare condition.
  • a problem with absorption of CSF into the vascular system
This occurs due to a blockage of flow of CSF from the the subarachnoid space
into the vascular system. This may be a congenital defect resulting in the absence of arachnoid granulations or the granulations may be
clogged up with red blood cells following a subarachnoid haemorrhage. It can also be as a result of stenosis of the internal jugular vein, inflammatory exudate, venous thrombosis or increased pressure of the venous sinuses.

Hydrocephalus in children can result in head enlargement. If the cranial sutures have not closed, then hydrocephalus causes the brain to expand, pushing the skull bones apart. If this happens in- utero it can prevent normal vaginal delivery and caesarean section is the only option.

There are two types of hydrocephalus:
  1. non- communicating- Blockage of the CSF flow due to a blockage, resulting in increased intracranial pressure.
  2. Communicating- Increased pressure of CSF that is not caused by an obstruction. This often occurs in the elderly where there is an enlargement of the ventricular system, with a normal CSF pressure. This is called normal pressure hydrocephalus (NPH).

Symptoms

One of more of these symptoms may be experienced as a result of hyrocephalus:
  • Headache
  • Nausea
  • vomiting
  • confusion
  • disturbances in vision
  • poor coordination
  • urinary incontinence


Imaging of the ventricular system

CT and MRI are useful in order to visualise the ventricular system of the brain. They are safe to use.

Investigations

Lumbar puncture 19078.jpg
Lumbar puncture is a procedure that involves obtaining a sample of CSF from the lumbar cistern with a needle around level L4 of the spine. The CSF pressure is then determined from the CSF fluid. This procedure is carried out after numbing the lower region of the back using local anaesthetic.

Lumbar drain
This is when a tube is inserted into the lumbar region of a person's back for a few days. If it alleviates the symptoms then this i an indication that the levels of CSF in the subarachnoid space is too high. This procedure is carried out after applying local anaesthetic to the lower back region.

Lumbar infusion test

A lumbar infusion test can also be used to help diagnose NPH and whether or not surgery is required. This is important as the presenting symptoms of NPH may also be that of Alzheimer's Disease, therefore it is important to diagnose the condition correctly. During this procedure, fluid is administered into the lumbar cistern and the CSF pressure is monitored. A rise sustained in CSF pressure suggests that there is an inability to absorb the fluid adequately. A needle inserted in the lumbar region of the back via local anaesthetic monitors the CSF pressure.

Treatment

The usual treatment of hydrcephalus is the insertion of a shunt. This provides an alternative route for the CSF, allowing drainage at another location in the body and therefore relieving the intracrananial pressure. There are several types of shunt:
  • VA shunt (ventriculo-atrial) - one end of the valved pipe is placed in a cerebral ventricle and the other is in the heart.
  • VP shunt (ventriculo- peritoneal) - the tube extends from the cerebral ventricle to the peritoneum
  • LP shunt (lumbar- peritoneal) - the tube extends from the subarachnoid space in the lumbar region (lumbar cistern) of the back to the peritoneum
  • Lumbar- subcutaneous shunt- This tube is placed from the lumbar cistern to a space directly under the skin, eg. the abdomen where the CSF can be drained. Unlike other shunts, this does not require general anaesthetic. However, the safety and efficacy of the procedure has not been deemed adequate. According to NICE guidelines it should not be carried out without the consent of the patient and their full understanding of the uncertainty of the procedure with regards to safety and efficacy. Furthermore, audit and review of the procedure is also required.

Meningitis


Meningitis is an infection that targets the arachnoid mater and pia mater (leptomeninges). It is usually contracted via the blood, however it can also occur secondary to trauma and due to spread of infections from the nasal cavity through the cribiform plate of the ethmoid bone. The infection can be viral, bacterial or parasitic in nature. It can be life-threatening if not treated. It may cause complications such as hydrocephalus, deafness, epilepsy and neurological damage.

Viral meningitis is the most common form of meningitis and is much less dangerous than bacterial meningitis. The meningococcal bacterium is the most common culprit of bacterial meningitis. There are 5 main groups of the meningococcal bacterium: A, B, C, W135 and Y. Meningococcal bacteria are commensal bacteria normally found in the nose and the back of the throat. It is unclear why some people have natural resistance to meningococcal bacteria and others do not. When meningococcal bacteria enter the bloodstream, they replicate and die releasing toxins that damage the blood vessels and organs.

People at highest risk of contracting meningitis are babies and infants whose immune system hasn't properly developed and young people aged 15 to 19, which is thought to be due to the increase number of carriers of the meningococcal bacteria. Increasing carrier numbers may be due to people of that age living and working in close proximity, for example in school and university.

Meningitis is a notifiable disease, therefore any doctor who suspects meningitis or meningococcal septicaemia is obligated by law to report it.

Symptoms

Initially symptoms are general and non- specific:
  • headache
  • nausea
  • fever
  • drowsiness

As the infection worsens:
  • photophobia
  • neck pain and stiffness (When neck is extended, legs raise)
  • ecchymosis

This is a medical emergency at this point!

Investigations

CRP and blood cultures are performed initially.

Lumbar puncture is the most important investigations for diagnosing meningitis. This is performed by positioning the patient on their side, applying local anaesthetic and inserting a needle just above level L4 of the spinal cord and extracting a sample of CSF. In bacterial meningitis the CSF pressure is usually elevated and there are elevated levels of protein, white and red blood cells and bacteria present in the CSF sample. Raised levels of lactate and reduced glucose levels in the CSF also suggest bacterial meningitis.

Treatment

If meningitis is suspected all patients should receive a empircal antibiotics while awaiting blood culture results. Be careful not to give antibiotics before taking the blood cultures as this may give a false- negative result.

For bacterial meningitis:
  • High dose intravenous antibiotics specific to the organism identified.
  • Fluids
  • Steroids- This may reduce rates of mortality, hearing loss and neurological deficits by dampening down the inflammatory response.

Viral and parasitic meningitis are usually self- limiting and following bed rest, fluids and analgesics the patient will make a full recovery.

Prevention DownloadedFile.jpeg

Vaccinations against meningococcal C strain is part of the childhood immunisation programme and this is also available to people aged under 25 who have not received it.

Vaccinations against pneumococcal infection and haemophilus influenzae which can cause meningitis are also part of the childhood immunisation programme.

Measles and mumps are included in the childhood vaccination programme. These diseases can also cause meningitis.

A local slant- meningitis in Wales

There were 77 notifications of meningitis in Wales in 2009:
  • 34 were of meningococcal origin
  • 17 were following pneumococcal infection
  • 17 were viral in nature

and 49 notifications of meningococcal septicaemia.

Public Health Wales is an organisation that collects and analyses statistics and data regarding the levels of infectious disease in Wales. Meningitis and meningococcal septicaemia are two such diseases that are monitored, in order to ascertain prevention and control plans. Based on this, advice on immunisation protocols is given and the necessary services are put in place to achieve these. Public Health Wales also try to prevent the spread of meningococcal disease in the community by identifying local cases and following them up.

Public Health Wales has been advocating a change from the use of rifampicin to ciprofloxacin in first line chemoprphylaxis for all close contacts of a sufferer of meningococcal septicaemia since october 2011. Ciprofloxacin is more useful in that it is easily accessible, it is a single dose and it it does not interfere with the efficacy of the oral contraceptive pill.

Here is a graph taken from the Public Health Wales website illustrating the rates of meningitis and meningococcal disease in Wales between 1999 and 2010:

        meningitis notifications in Wales: 1999-2010
meningitis notifications in Wales: 1999-2010

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