MENINGITIS, neurology, internal Medicine

Neurology

1. MENINGITIS ATUNWA TEMIDAYO

2. OUTLINE Introduction EPIDEMIOLOGY RISK FACTORS AETIOLOGY ROUTES OF INFECTION CLASSIFICATION PATHOPHYSIOLOGY CLINICAL FEATURES MANAGEMENT COMPLICATIONS PREVENTION DIFFERENTIALS CONCLUSION REFERENCES

3. Introduction Meninges refers to the membranous coverings of the brain and the spinal cord 3 layers : The dura mater The arachnoid mater The pia mater Combination of the pia and the arachnoid mater makes up the leptomeninges. Subarachnoid space : is the space that exists between the arachnoid mater and the pia mater. It consists of cerebrospinal fluid

4. DEFINITION Meningitis is an acute inflammation of the leptomeningeal coverings of the brain or spinal cord. Meningitis can be life threatening due to the proximity to the brain and the spinal cord Characterized by a classic triad of fever, neck stiffness and altered mental status.

5. EPIDEMIOLOGY The exact incidence of meningitis worldwide is unknown The incidence of meningitis due to  N. meningitidis  is highest in a region of sub-Saharan African known as the “meningitis belt” extends from Senegal to Ethiopia, and is characterized by seasonal epidemics during the dry season (dec-june) At least 350 million people are at risk for meningitis during these annual epidemics. In Nigeria, the belt covers all the 19 Northern states including the FCT Meningitis is a life-threatening disorder that is most often caused by bacteria or viruses. Before the era of antibiotics, the condition was universally fatal. Nevertheless, even with great innovations in healthcare, the condition still carries a mortality rate of close to 25%.

6. ROUTES OF ENTRY Haematogenous spread Extension from nearby infected structures such as otitis media, sinusitis or epidural abscess Direct spread from traumatic injuries with leakage of CSF as in fracture of the base of the skull Infected congenital malformation e.g myelomeningocele.

7. RISK FACTORS Anatomical defects: skull fracture, congenital malformations- spinal bifida, Opsonization defect: SCD, Splenectomy(OPSI), complement deficiency.

8. Immunocompromised states: severe burns, AIDS, concurrent infections -acute respiratory infections, individuals not vaccinated Iatrogenic factors : Ventricular shunt defect, cranial instrumentation

9. Demographic conditions : travel to endemic areas and large population displacements Climatic conditions :drought and dust storms Socio-economic factors: overcrowding ,poor living conditions

10. AETIOLOGY Can either be : Infective Non-infective

11. PATHOPHYSIOLOGY Following the entry into the bloodstream, the infecting organism crosses the blood-brain barrier. This triggers an inflammatory response in the meninges. Notably, the organisms proliferate much faster than elsewhere in the body, because of the lack of host defense mechanisms at this site. Due to the inflammation, there’s meningeal congestion and inflammatory cells infiltration (oedema) Also,there’s increased CSF pressure, protein content and cellular reaction Pus formation in layers CSF drainage obstruction leading to hydrocephalus/ CN damage Venous stasis may occur and lead to cerebral infarction

12. CLASSIFICATION OF MENINGITIS BASED ON DURATION Acute meningitis :The symptoms present within 0- 24hrs. Duration of illness is < 7days Subacute meningitis : Duration of illness is 1-4 weeks Chronic meningitis: Duration of illness is >4 weeks

13. CLASSIFICATION ON ETIOLOGY Acute Bacterial Meningitis Viral /Aseptic Meningitis Fungal meningitis Noninfectious Meningitis

14. ACUTE BACTERIAL MENINGITIS Also known as Acute Pyogenic Meningitis Onset is typically sudden, with rigors and high fever. Many bacteria can cause meningitis but geographical patterns vary, as does age-related sensitivity. In the ‘meningitis belt’ of sub-Saharan Africa, drought and dust storms are often associated with meningococcal outbreaks (Harmattan meningitis). Bacterial meningitis is usually part of a bacteraemic illness, although direct spread from an adjacent focus of infection in the ear, skull fracture or sinus can be causative. Pathology : pia-arachnoid mater is congested with polymorphs. A layer of pus forms. This may organize to form adhesions, causing cranial nerve palsies and hydrocephalus

15. VIRAL MENINGITIS Viruses are the most common cause of meningitis, usually resulting in a benign and self-limiting illness requiring no specific therapy. It is much less serious than bacterial meningitis unless there is associated encephalitis. Several viruses can cause meningitis, the most common being enteroviruses. Where specific immunization is not employed, the mumps virus is a common cause.

16. FUNGAL MENINGITIS Fungal meningitis is uncommon and usually occurs in the immunosuppressed. The yeast Cryptococcus neoformans is the commonest and an important cause of meningitis in those immunosuppressed by HIV infection. It does occur in the immunocompetent although non-HIV forms of immunocompromise should be sought. The presentation may be atypical with subacute or chronic meningism, fever, headache and symptoms of raised intracranial pressure occur.

17. CHRONIC MENINGITIS Can be caused by : Infections e.g Mycobacterium tuberculosis, Treponema pallidum Medications e.g NSAIDS, TMP-SMZ Malignancy SLE Behcet Meningeal symptoms may last for 4 weeks or more Pathology : In chronic infection (e.g. TB), the brain is covered in a viscous grey-green exudate with numerous meningeal tubercles. Adhesions are invariable. Cerebral oedema occurs in any bacterial meningitis

18. CLINICAL FEATURES SYMPTOMS Fever Headache Nuchal rigidity Photophobia Phonophobia Altered consciousness Convulsions Vomiting Lethargy Rash Myalgia

19. Sign Signs of meningeal irritation: Brudzinski's sign Kernig's sign Nuchal rigidity. Others petechial rash – Clinical cue to meningococcal meningitis hypotension Cushing triad [widened pulse pressure ( increasing systolic, decreasing diastolic ) bradycardia, and irregular respirations.] cranial nerve palsies- III, IV, VI, VII Papilloedema +/-

20. History and Examination Detailed history taking : Hx of fever,headache,neck stiffness Hx of recent infections such as upper respiratory tract infection Hx of trauma to the head Hx of possible complications Hx of care so far Physical Examination Assess the neurological status and vital signs Assess for signs of meningeal irritation Signs of raised intracranial pressure

21. INVESTIGATIONS Lumbar puncture and CSF analysis: done to confirm the diagnosis and exclude close differentials and is mandatory unless contraindications to this procedure include Signs of raised intracranial pressure. Eg. Bradycardia, abnormal respiration, hypotension, diplopia, abnormal pupillary response, papilledema Suspicion of intracranial mass lesion as lumbar puncture may cause coning of cerebellar tonsils Coagulopathy/ thrombocytopenia Local infection at lumbar puncture site Vertebral anomalies Respiratory compromise Cardiovascular compromise/ shock

22. CSF FINDINGS IN DIFFERENT TYPES OF MENINGITIS

23. Blood microscopy, culture, and sensitivity: to identify the infecting organism and determine the most suitable antibiotics of choice Staining : Gram staining – gram-positive diplococci (pneumococcus) Gram-negative cocci (meningococcus) Ziehl- Neelsen stain – demonstrates Acid Fast Bacilli (tuberculosis) Indian ink – stains fungi MRI/CT scans with or without contrast: to rule out other disorders e.g intracranial mass lesions, SAH Serological tests: For viruses Ancillary investigations: FBC and differentials: may reveal leukocytosis, neutrophilia(in bacterial meningitis), lymphocytosis (in viral meningitis) RBG: to ascertain the blood glucose level Chest X-Ray: in TB

24. TREATMENT Goal of treatment to sterilize the CSF by clearance of the infecting organism Identification and management of possible complications

25. For bacterial meningitis: Below is a list of antibiotics that can be used as drug of choice Third-generation cephalosporin : ceftriaxone (4gm stat, 2gm 12 hourly cefotaxime (200 mg/ Kg24 hours, given every 6 hours, ceftazidime penicillin chloramphenicol, ampicillin, cotrimoxazole, vancomycin anti-TB drugs

26. Adjunctive corticosteroids is useful in both children and adults - Dexamethasone 0.6 mg/kg i.v. for 2- 4 days), given with or before the first dose of antibiotics Antivirals for viral meningitis Sedatives for restlessness Anticonvulsants e.g phenytoin for seizure Antipyretics for fever Adequate hydration and nutrition Frequent monitoring and evaluation.

27. Identification and mgt of possible complications e.g shock, raised intracranial pressure; Iv frusemide 40mg, Mannitol @ 0.5-1.0 g/ Kg. Surgical ventricular drainage if obstructive hydrocephalus develops Physical therapy ig brain damage occurs as a sequelae Skilled nursing is essential during the acute phase of the illness, and adequate hydration and nutrition must be maintained.

28. COMPLICATIONS

29. PREVENTION Routine immunization: Hib, PCV, MenA Mass vaccination during epidemics Chemoprophylaxis: following meningococcal exposure Vaccination of special risk groups: Sickle cell anaemia, functional or anatomic asplenia, HIV infection. Avoid overcrowding especially during endemics Ventilation of sleeping areas

30. DIFFERENTIAL DIAGNOSIS Encephalitis Migraine Brain abscess Brain Neoplasm Subarachnoid hemorrhage Meningism from tonsillitis, otitis media, pneumonia

31. PROGNOSIS Outcomes depend on patient characteristics such as age and immune status, but also vary depending on the etiologic organism.

32. CONCLUSION Meningitis is potentially life-threatening and has a high mortality rate if untreated; delay in treatment has been associated with a poorer outcome.

33. REFERENCES Kumar and Clark Textbook of Clinical Medicine, 9th edition Davidson's principles of Medicine, 22nd edition A Compendium of clinical medicine, 4th edition, A. O Falase CDC fact sheet on meningitis NCBI

34. THANK YOU