Meningitis

Here’s another cause of headache and one that you really need to exclude in anyone that presents with a headache as it is a medical emergency. If someone has a headache you need to ask them about neck stiffness, fever, photophobia and rashes.

I was worried I had meningitis for all of two minutes, because I had a headache and a stiff neck. Not worried enough to actually do anything about it though.


Meningitis

Definition: inflammation of the leptomeningeal coverings (pia mater and arachnoid) of the brain, most commonly caused by infection. Image result for meninges anatomy

Aetiology/risk factors:

Bacterial

Neonates: Group B strep., E.coli, Listeria monocytogenes

Children: Streptococcus pneumoniae, Neisseria meningitides, Haemophilus influenza (less common because of vaccine)

Adults: Streptococcus pneumoniae, Neisseria meningitides, TB (in immunocompromised)

Elderly: Streptococcus pneumoniae, Listeria monocytogenes

Viral

-Enteroviruses e.g. Coxsackie A & B (46%)

-Herpes Simplex Virus 2 (31%), Herpes Simplex Virus 1 (4%)

-Herpes Zoster Virus, Epstein-Barr Virus

-Cytomegalovirus (in immunocompromised)

-Mumps virus

Fungale.g. cryptococcus (in immunocompromised, associated with HIV)

Other: aseptic meningitis secondary to autoimmune disorders (Sarcoidosis, SLE), malignancy (lymphoma, leukaemia, metastasis), medication (NSAIDs, trimethoprim, azathioprine)

 

Risk factors: close communities (e.g. dorms), basal skull fractures, mastoiditis, sinusitis, inner ear infections, alcoholism, immunodeficiency, splenectomy, sickle cell anaemia, CSF shunts, intracranial surgery.

Epidemiology: UK Public Health Laboratory Services receives ∼2500 notifications/year. More common in recent visitors to Hajj (meningococcal).

Symptoms:

Early

-acute, severe headache, felt over most of head

-leg pains, cold hands and feet, abnormal skin colour

-fever

Later

-neck stiffness (meningeal irritation)

-photophobia

-nausea & vomiting

 

Signs:

-pyrexia

Later

-Kernig’s sign- pain and resistance on passive knee extension with hip fully flexed

-Brudzinski’s sign- flexion of hips on neck flexion

Image result for kernig sign

-altered mental state- reduced consciousness, coma

-seizures (∼20%) +/- focal CNS signs (∼20%)  +/- opisthotonus (arching of body with neck hyperextension)

 

Image result for opisthotonus

Opisthotonus

-non-blanching, purpuric rash (characteristic of meningococcal septicaemia)

Image result for meningococcal rash

 

Signs of sepsis = slow capillary refill

hypotension

raised/normal temperature and pulse

DIC (Disseminated Intravascular Coagulation)- purpuric rash

Investigations:

U&Es, FBC (reduced WCC if immunocompromised = get help), LFT, glucose, coagulation screen (major coagulopathy is a contraindication to lumbar puncture)

Blood culture, throat swabs, rectal swab (viruses), serology (e.g. EBV, HIV)

-Urgent CT head- to exclude raised intracranial pressure, which is a contraindication to lumbar puncture due to risk of brain herniation.

Signs of raised ICP: papilloedema (on fundoscopy), fits, focal neurological deficit, reduced consciousness

-Lumbar puncture- if CT negative. Look for signs of infection in the cerebrospinal fluid (CSF). Can be done without CT if GCS 15 (conscious level intact), no symptoms of raised intracranial pressure, and no focal neurology. Do not attempt LP if septicaemic/shock.

-Opening pressure of CSF may be raised > 40, typically 14-30 (Normal = 7-18 cm)

-Send CSF for microscopy, culture & sensitivities, gram stain, protein, glucose, virology/PCR, lactate 

Bacterial turbid CSF, raised neutrophils, low glucose, high protein, bacteria cultured

Viral usually clear/may be a bit cloudy CSF, raised lymphocytes, normal glucose, slightly high protein

-Do CSF PCR in viral meningitis to identify virus

Chest x-ray- TB?

 

Management:

Bacterial meningitis- the dangerous one (viral meningitis is usually self-limiting)

-Give antibiotics immediately

-Do not delay antibiotics for investigations

-If patient presents with signs of meningitis and is not in hospital, give BENZYLPENICILLIN (1.2g IM/IV) before admitting.

-In hospital:

Unknown organism:

< 55 years = CEFOTAXIME (2g/6h slow IV)

> 55 years = CEFOTAXIME +AMPICILLIN (2g IV/4h) (for Listeria)

-Local guidelines vary. Once organism isolated, seek urgent microbiological advice.

-If meningitic, without signs of septicaemia, also give DEXAMETHASONE (4-10mg/6h IV), shortly before or with first dose of ABx. Give antibiotics after a Lumbar Puncture, unless this will be delayed by > 30mins or there are contraindications.

-If septicaemic, lumbar puncture should not be attempted. Antibiotics given immediately and critical care team contacted. If there are signs of shock, they need to go to ICU (intensive care unit) for management of septic shock.

-If there are signs of raised intracranial pressure, they should also be taken to ICU.

 

Prophylaxis- RIFAMPICIN or CIPROFLOXACIN (if close contact with patient)

Complications:

-septicaemia, shock, DIC

-renal failure

-fits

-peripheral gangrene

-cerebral oedema

-cranial nerve lesions

-cerebral venous thrombosis

-hydrocephalus

-Waterhouse-Friderichsen syndrome (bilateral adrenal haemorrhage)

Prognosis:

-Mortality rate from bacterial meningitis is high (10-40% with meningococcal sepsis), higher in developing countries.

-Viral meningitis is self-limiting.

References: Cheese & Onion, Rapid Medicine
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