Tuberculous Meningitis
Extrapulmonary Tuberculosis
Definition: Tuberculous meningitis (TBM) is the most severe type of extrapulmonary tuberculosis, though it is the least common type. It can occur as the sole manifestation of TB or concurrent with pulmonary or other extrapulmonary sites.
Tuberculous meningitis (Tonsil Stones)
Etiology: Mycobacterium tuberculosis.
1. Pathophysiology
TBM develops in two distinct steps.
Step 1: Systemic Seeding
Droplet Inhalation
↓
Phagocytosis (Alveolar Macrophages)
↓
Regional Lymph Nodes (Primary Complex)
↓
Bacteremia & Organ Seeding
↓
Seeding of Meninges/Brain
Forming Rich Foci (Subpial/Subependymal caseous lesions)
Forming Rich Foci (Subpial/Subependymal caseous lesions)
Step 2: Rupture & Inflammation
Rich Focus Increases in Size
↓
Ruptures into Subarachnoid Space
↓
Severe Inflammatory Response (Thick Exudate)
⚠ Pathology of Complications
- ➢ Basal Meningitis: Causes CN III, VI, VII dysfunction.
- ➢ Basilar Cistern Obstruction: Causes Obstructive Hydrocephalus.
- ➢ Deep Rupture: Causes Tuberculoma or Abscess.
- ➢ Vascular: Phlebitis, arteritis, thrombosis → Infarcts.
2. Clinical Features
General Presentation: Subacute febrile illness.
Note: Neck stiffness may be absent early!
Note: Neck stiffness may be absent early!
- ➢ CNS Dysfunction: Personality change, vomiting, lethargy, confusion.
- ➢ CN Palsies: III, VI, VII.
- ➢ Focal Deficits (Sudden): Monoplegia, hemiplegia, aphasia, tetraparesis.
- ➢ Movements: Tremor (Common), myoclonus, choreoathetosis.
- ➢ Fundoscopy: Choroidal tubercles.
3. Diagnosis
| Test | Findings |
|---|---|
| CSF Exam |
High Protein, Low Glucose, Lymphocytosis. AFB Smear/PCR is best for early diagnosis. |
| CB-NAAT | High sensitivity; detects drug resistance. |
| Imaging (CT/MRI) | Basal enhancement, Hydrocephalus. |
| Others | Mantoux (Positive), CXR (Pulmonary TB), HIV check. |
4. Treatment
Start immediately on strong clinical suspicion.
Protocol
Intensive Phase (2 Months)
4 Drugs: Isoniazid, Rifampicin, Pyrazinamide, Ethambutol
4 Drugs: Isoniazid, Rifampicin, Pyrazinamide, Ethambutol
↓
Continuation Phase (7-10 Months)
2 Drugs: Isoniazid, Rifampicin
2 Drugs: Isoniazid, Rifampicin
Steroids are Mandatory
Give Dexamethasone (12mg) or Prednisolone (60mg) to all patients.
Full dose 3 weeks → Taper over 3 weeks.
Give Dexamethasone (12mg) or Prednisolone (60mg) to all patients.
Full dose 3 weeks → Taper over 3 weeks.
Surgery: Decompression for hydrocephalus.
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