Meningitis Flashcards
what is the meningism symptom complex?
headache, photophobia and vomiting with muscle spasm leading to neck rigidity. Meningism may be caused by meningitis or sub-arachnoid haemorrhage or infection accompanied by bacteraemia
define meningitis…
infection of the meninges, leads to inflammation and signs of meningeal irritation and is an important potential cause of death or permanent disability.
what are the 3 layers of Meningies?
The brain is suspended in cerebrospinal fluid (CSF) and surrounded by three layers of meninges. The pia mater and arachnoid constitute the leptomeninges while the more substantial dura mater or pachymeninges lies on the exterior forming a protective layer.
Pathogenesis
- Attachment to mucosal epithelial cells (eg, bacteria and mumps virus to nasopharyngeal and oropharyngeal mucosa, enteroviruses to intestinal mucosa).
- Transgression of the mucosal barrier.
- Survival in the blood stream.
- Entry into CSF.
- Production of overt infection in the meninges with or without brain infection (encephalitis).
list the common bacterial causes of meningitis
Neisseria meningitidis (meningococcus), Streptococcus pneumoniae (pneumococcus). In neonates: E. coli and Group B streptococci
list the common viral causes of meningitis
Enteroviruses: Echoviruses, Parechoviruses, Coxsackie A and B viruses, (Poliovirus - not seen in UK), Mumps (now very rare due to MMR vaccine), Herpes simplex virus.
sy/sx
Meningitic sy - Headache, Neck stiffness (Kernig’s: Straightening leg c¯ hip @ 90O, Brudzinski’s: lifting head → lifting of legs), Photophobia
Neurological sy - ↓ GCS → coma, Seizures (20%), Focal neuro (20%): e.g. CN palsies
Septic - Fever, ↓BP, ↑HR, ↑CRT, Purpuric rash, DIC
what common conditions present with meningism?
influenza, tonsillitis, pneumonia, sinusitis, urinary, tract infection (particularly in women), and any severe bacteraemic illness. Important non-infective causes include subarachnoid haemorrhage and migraine. Meningeal infection should be considered in every patient with a history of upper respiratory tract infection accompanied by one of the “meningeal” symptoms of vomiting, headache, stiff neck, lethargy or clouding of consciouness.
examination of a suspected pt with menignism/meningitis
pyrexia? Conciousness level, skin and conjunctival petichiae, other rashes, tachy/bradycardia, hypotension, focal neurologicla signs or any CN Palsies, Kernigs sign: with the hip flexed, the patient’s leg cannot be straightened due to hamstring spasm in meningism. also touching chin to chest is v hard.
Ix
Bloods: FBC, U+Es, clotting, glucose, ABG, Blood cultures
LP: MCS, glucose, virology/PCR, lactate
what are the Contraindications to LP? (Try LP Unless ContraINdicated)
Thrombocytopenia Lateness (delay in antibiotic admin) Pressure (signs of raised ICP - space occupying lesion, so do a CT scan) Unstable (Cardio + resp systems) Coagulation disorder Infection at LP site Neurology (focal neurological signs)
what are the common tests done on CSF?
CSF Microbiology: Gram stain (and ZN if appropriate), Differential cell count (neutrophil polymorphs or lymphocytes), Antigen detection test (latex agglutination), Bacterial culture, Mycobacterial or fungal culture (if appropriate), PCR for viruses (if appropriate), PCR for bacteria (if appropriate), CSF Biochemistry: Glucose and protein.
Principles of Mx of acute bacterial meningitis
Early clinical recognition. Rapid detection of pathogen. Rapid initiation of appropriate bactericidal antimicrobial therapy. Early recognition and treatment of sequelae of septicaemia (eg, DIC with shock, hypoxia, acidosis and adrenal insufficiency). Antibiotic prophylaxis (when appropriate) of close contacts.
Management procedure –>
o2, iv fliuids, LP, abx - iv Benzylpenecillin or Dexamethasone or ceftriaxone
