Meningitis

Inflammation of the membranes encapsulating the brain (meningitis) can be caused by both bacteria and viruses. Especially bacterial meningitis is a life threatening disease where rapid diagnosis and initiation of antibiotic treatment are pivotal. Patients surviving meningitis often have neurological sequelae like deafness, muscle weakness or neuropsychological deficits.

The last 20 years, the frequency of bacterial meningitis in children has substantial decreased due to the introduction of vaccinations. Due to these changes bacterial meningitis has become a disease primarily occurring in adults. The most frequent causes of bacterial meningitis are the pneumococcus (Streptococcus pneumoniae) and the meningococcus (Neisseria meningitidis). The meningococcus is primarily found in in children and young-adults (15-25 year) while the pneumococcus mainly causes disease in infants and elderly people.

Meningitis is often preceeded by ear of sinus infections after which the bacterium invades the brain and meninges. Initial symptoms can be similar to common influenza infections, but eventually the typical signs as severe headache, nausea, neck stiffness and drowsiness develop. The disease course can be fulminant, and therefore fast recognition and treatment is important. To diagnose meningitis a lumbar puncture should be performed to confirm bacterial presence in the cerebral spinal fluid. Sometimes, cranial imaging by CT or MRI are necessary before the lumbar puncture, to exclude other diseases such as brain abscess. This should however not lead to a delay in initiation of treatment. Bacterial meningitis is treated with antibiotics and anti-inflammatory drugs (dexamethason).

Even when the disease is recognized early and the treatment is started, many patients experience complications due to meningitis. Bacterial meningitis patients are at risk of developing hearing loss (20-25%), stroke (20-25%), seizures (25%) or hydrocephalus (5%). Because of these complications it may be necessary to perform a CT or MRI scan of the brain, electroencephalography (EEG) or a new lumbar puncture during hospital admission. Treatment with antibiotics should be continued during 1 to 3 weeks, depending on which bacterium is identified as causative agent.

Sometimes it be necessary to consult other specialists, for example a cardiologist to determine if the cardiac valve is inflamed or an ear-nose-throat (ENT) physician to treat ear or sinus infections, or treat hearing loss with implantation of a hearing aid.

Viruses can cause both meningitis and encephalitis. In general, viral meningitis is a less severe disease compared to bacterial meningitis or viral encephalitis. The disease mimics an influenza infection and resolves spontaneously after a few days. Treatment is often not indicated, expect for analgesics for the headache.

Viral infection of the brain (encephalitis) is a severe disease. Patients often present on the emergency room with complaints of epileptic seizures, fever, behavioral changes or even coma. Viral encephalitis can be diagnosed by demonstrating a virus in the cerebrospinal fluid. Furthermore, a MRI scan is often necessary to determine the severity of brain damage and exclude other neurological diseases. Viral encephalitis is treated with antiviral medication (Aciclovir). Unfortunately, mortality remains high and many surviving patients have cognitive problems.

Chronic meningitis is defined as meningitis that last for at least one month. Causes of chronic meningitis consist of slowly progressing infections, like tuberculosis, HIV or syphilis. Diseases that can be transmitted by animals, ticks or insects are often suspected as a cause (like cat scratch disease, Lyme disease or West Nile virus) or tropical infections acquired during travel.

Multiple other conditions than infections can be the cause of chronic meningitis, like the use of specific types of medication, cancer or autoimmune inflammatory diseases (e.g. sarcoidosis). Presenting symptoms in patients with chronic meningitis are variable and may consist of fever, headache, nausea, memory deficits or confusion. Usually these symptoms develop gradually and can differ in severity.

To diagnose the cause of chronic meningitis extensive testing may be necessary, such as blood tests, several lumbar punctures, brain scans or imaging of other parts of the body. Sometimes the cause of chronic meningitis can not be established and treatment be initiated to treat infection or autoimmune disease without certainty of the final diagnosis. In the patients treatment response may be an important diagnostic tool to identify the cause of chronic meningitis. As diagnosing the cause of chronic meningitis is often difficult, these patients are often referred to the AMC for a second opinion.