Meningitis

Causes
Viral or aseptic meningitis is the most common form and may be caused by enteroviruses.
Meningococcal disease is the most common (Neisseria meningitides) - infancy and adolescence and over the Winter months.
Pneumococcal - commonest cause in elderly people. Often have a distant focus of pneumococcal infection like pneumonia, otitis media, mastoiditis, sinusitis or endocarditis. Has a 30% mortality rate.
TB meningitis - often develop gradually over days or even weeks and is more  common in the immunocompromised, especially with HIV.
Listeria meningitis remains uncommon. Neonates, the elderly, and immunocompromised people are at greatest risk.


Recurrent lymphocytic meningitis, also known as Mollaret’s meningitis, is a rare disease that is estimated to have a prevalence of 2.7 per 100 000 population. HSV-2 is the most common cause of recurrent lymphocytic meningitis, being responsible for 84% of recurrent meningitis in one study.
A suddenly worsening headache, followed by emerging signs of meningism, is often associated with rupture of the abscess. Rupture of a brain abscess is associated with a high mortality: up to 80%. Emergency surgery is indicated.


Clinical Presentation When a patient recovers from bacterial meningitis, headache, fatigue, and difficulty with coordination, concentration, and memory may persist for several months.


Rash - may be petechial, or in its early stages may be erythematous. The rash occurs in at least 60% of adults.


Triad of fever, headache, and neck stiffness(70% sensitivity) in less than 50% of patients. Changes in mental state are relatively sensitive and tend to occur more often in bacterial than viral meningitis.

Kernig's test is positive if there is pain or resistance in the lower back or posterior thigh when the knee is extended while the hip is flexed to 90°. Kernig's sign can be a useful test if positive, but a negative test does not exclude meningitis.

Brudzinski’s sign is not specific for meningococcal meningitis. You can elicit the sign by passive flexion of the neck, resulting in flexion of the hips and knees if positive.


Encephalitis  has a similar presentation to meningitis, but confusion and drowsiness tend to be more prominent.


Management of Suspected Meningitis in the Emergency Department

1. Recognise
2. Investigate – Take extra two EDTA (purple) tubes for meningococcal or pneumococcal DNA using PCR. Do not wait for the results before commencing treatment. It is difficult to differentiate viral meningitis from bacterial meningitis on clinical grounds alone so we need to do a LP.
3. Treat –
   a. Sepsis 6 with antibiotics as per trust antimicrobial guidelines
   (Ceftriaxone 2g + amoxicillin 2g if >50years or immunocompromised)
   b. Dexamethasone 10mg IV
   c. Aciclovir if features of encephalitis (fluctuating consciousness, motor or sensory deficits, altered behaviour and personality changes, and speech or movement disorders).
   There are currently no treatments with a proven benefit for the common causes of viral meningitis, although acyclovir is often used, despite it being nephrotoxic and lowering seizure threshold. It does reduce the mortality of encephalitis from 70% to less than 30%. Treatment should be supportive.
4. CT would be indicated if there are focal neurological signs, papilloedema, controlled or uncontrolled seizures, GCS <12 or diagnostic uncertainty. The medical team may ask the ED team to arrange the CT, but this should not delay their review of the patient.
5. For continuity of care, it is expected that the medical team will report “acute meningitis” to  Health Protection Team (SLHPT) .
6. Isolate – as per trust policy
   A patient with known or suspected meningococcal meningitis should be isolated in a single room with droplet precautions for 24 hours from the time that effective antibiotic treatment has been started.
   Staff caring for the patient should observe the standard infection control precautions and wear FFP3 masks, gloves and aprons.
   Staff performing procedures that may generate aerosols, for example suctioning, intubation or inserting an airway, should wear properly fitted FFP3 masks and eye protection.
7. Antibiotic Prophylaxis for close contacts should be coordinated by SLHPT. OH Assist will coordinate antibiotic prophylaxis for healthcare workers
   Antibiotic prophylaxis is offered to the following groups of people:
8. Those who have had prolonged close contact with the patient during the seven day incubation period. This includes people who live or sleep in the same household, dormitory or halls of residence.
9. Intimate (kissing) contacts.
10. Those exposed transiently to large droplets from the upper respiratory tract of the patient during their admission to hospital. For example, a healthcare-worker inserting an airway or suctioning the upper respiratory tract without wearing appropriate personal protective equipment may be at risk.

References
http://www.journalofinfection.com/article/S0163-4453(16)00024-4/abstract http://www.journalofinfection.com/cms/attachment/2048213088/2058279234/mmc1.pdf
https://www.uptodate.com/contents/viral-encephalitis-in-adults?source=search_result&search=meningitis%20aciclovir&selectedTitle=3~150 http://lgnet/download.cfm?ver=10662
https://www.rcemlearning.co.uk/modules/intracranial-infections/
http://learning.bmj.com/learning/modules/flow/ICH.html?execution=e1s1&moduleId=5003335&status=LIVE&action=start&_flowId=ICH&sessionTimeoutInMin=90&locale=en_GB&shouldStartAtQuestionSection=false
http://learning.bmj.com/learning/modules/flow/ICH.html?execution=e2s1&moduleId=10041919&status=LIVE&action=start&_flowId=ICH&sessionTimeoutInMin=90&locale=en_GB&shouldStartAtQuestionSection=false