Tuberculous Meningitis

Tubercular meningitis

Insiduous / gradual onset of fever over a duration of two weeks, with features of raised intracranial tension in the form of vomiting and altered sensoriurn with characteristic basal exudates and hydrocephalus on cranial CT scan are almost characteristic of tuberculous meningitis.

Ref: Text Book of Pediatrics By Nelson, 17th Edition, Page 965, 966

CSF findings in tubercular meningitis includes:

• Elevated opening pressure
• High leukocyte count ( 1000/microl) predominantly lymphocytes
• Increased protein (100 – 800/mg/dl)
• Low glucose 
• AFB seen on direct smear of CSF
• Culture of CSF is diagnostic and is the gold standard
  

Typical CSF findings in tubercular meningitis are increased protein, decreased sugar and increased lymphocytes.

Ref: Harrison’s Principles of Internal Medicine, 16th Edition, Page 2487; Tuberculosis Research and Treatment Volume 2011 (2011), Article ID 798764, 9 pages.

CSF findings consistent with TB meningitis are : yellowish in appearence, elevated opening pressure, increased cell count predominantly lymphocytes, low glucose (20-40mg/dl) and elevated protein levels (1 -5 g/l) .

Reference:
Harrison’s Principles of Internal Medicine 18th edn chapter 381.

Ans. is ‘b’ i.e., 100 to 499; ‘c’ i.e., 500 to 999

o In Bacterial meningitis —> 1000-100000/ 1 mainly neutrophils

o In viral meningitis            —>           10-100/ 1 mainly lymphocytes

o In TB meningitis              —>           100-1000/ 1 mainly lymphocytes.

Ans. is ‘a’ i.e., Mycobacterium Tuberculosis

lnsiduous /gradual onset of fever over a duration of two weeks, with features of raised intracranial tension in the form of vomiting and altered sensorium with characteristic basal exudates and hydrocephalus on cranial CT scan are almost characteristic of tuberculous meningitis.

TUBERCULOUS MENINGITIS

J                               Tuberculous meningitis usually arises from the formation of metastatic caseous lesions in the cerebral cortex or meningitis that develops during the lymphohaematogenous spread of primary infection. This initial lesion increases in size and discharges tubercle bacilli in the subarachnoid space.

o This results in gelatinous basal exudate which interferes in the normal flow of CSF, in and out of the ventricular system at the level of basal cisterns leading to a communicating hydrocephalus.

Clinical manifestations of tuberculous meningitis

o The clinical course of TB meningitis has three stages ‑

Prodromal stage or stage of invasion

             Insidious onset                                                      Headache and vomiting

             Low grade fever, loss of appetite                              Photophobia

             Disturbed sleep                                                      Constipation

Stage of meningitis

Signs of meningeal irritation develops – Neck rigidity, Kernig’s sign

Stage of coma

             Loss of consiousness                            Bradycardia

             Pupils arc dilated & fixed                       Chyne-strokes or Biot type of respiration

             Episodic decerebration

CT findings in TBM :

1. Basal cisterns are obliterated by isodense / hyperdense exudate
2. Post contrast there is a avid enhancement of the basal meninges extending into the ambient, sylvian, pontine and chiasmatic cisterns.
3. Meningeal enhancement may continue over the cerebral and cerebellar hemispheres.
4. Hydrocephalus is present in 45-87% of patients at time of diagnosis.

Ans. is ‘d’ i.e., Parkinsonism

Complications of TB meningitis

• There may be infarcts in the brain due to vascular occlusion
• Various neurological manifestations seen with TBM include :
• Hemiplegia (20%), quadriplegia (19%), monoplegia (3%)             
• Cranial nerve palsies (14%)
• Hemiballismus (11%)                                                                             
• Decerebrate Rigidity (3%)
• Tremors (6.1%)                                                                                       
• Decorticate Rigidity (3%)
• Midline cerebellar syndromes (4%)                                                     
• Cerebellar Hemispheric Lesions (1.0%)

Ptosis & Ophthalmoplegia are frequent in Coma stage in tuberculous meningitis –

Ans. is ‘b’ i.e., Low sugar + High protein, and Lymphocytosis

CSF in TB meningitis

o Low sugar                         o Predominant cells —> Lymphocytes         o Opening pressure is elevated

o High protein                     o Very low chloride

Answer is D (Tuberculosis):

‘The commonest cause of adrenal insufficiency (Addison’s disease) in underdeveloped countries is Tuberculosis, followed by autoimmune disorders.’

Answer is D (Tuberculosis):

‘The commonest cause of adrenal insufficiency (Addison’s disease) in underdeveloped countries is Tuberculosis

Ans:C.)Low opening pressure.

CSF Findings in Tubercular Meningitis

• CSF typically is clear or slightly turbid.
• If the CSF is left to stand, a fine clot resembling a pellicle or cobweb may form.
• This faintly visible “spider’s web clot” is due to the very high level of protein in the CSF (ie, 1-8 g/L, or 1000-8000 mg/dL) typical of this condition.
• Hemorrhagic CSF also has been recorded in proven cases of TBM; this is attributed to fibrinoid degeneration of vessels resulting in hemorrhage.
• CSF typically has a pleocytosis, an elevated protein level, and marked hypoglycorrhachia.
• The chloride contents of CSF and plasma sample and the ratio of CSF to plasma chlorides decreased in tuberculous meningitis group (<102.150mmol/L, <101.75mmol/L and
• CSF opening pressure is  is usually elevated in tuberculous meningitis.

Answer is C :High Chloride Levels

CSF Findings in Tubercular Meningitis

• CSF typically is clear or slightly turbid.
• If the CSF is left to stand, a fine clot resembling a pellicle or cobweb may form.
• This faintly visible “spider’s web clot” is due to the very high level of protein in the CSF (ie, 1-8 g/L, or 1000-8000 mg/dL) typical of this condition.
• Hemorrhagic CSF also has been recorded in proven cases of TBM; this is attributed to fibrinoid degeneration of vessels resulting in hemorrhage.
• CSF typically has a pleocytosis, an elevated protein level, and marked hypoglycorrhachia.
• The chloride contents of CSF and plasma sample and the ratio of CSF to plasma chlorides decreased in tuberculous meningitis group (<102.150mmol/L, <101.75mmol/L and
• CSF opening pressure is  is usually elevated in tuberculous meningitis.

Answer is D (Tubercular meningitis):

Elevated CSF protein and decreased sugar and chloride levels alongwith characteristic clinical features of meningitis suggest a diagnosis of Tubercular meningitis.

Typical CSF features of Tubercular Meningitis are :

• Cells :Mononuclear cells (except early infection when PMN cells are seen)Q
• Protein :Increased above 40 mg/100 ml.^Q
• Sugar :Usually reduced to less than 2/3′^‘ of blood sugar Q.
• Chloride level :usually reduced.

Important points about TBM :

• In TBM, the exudate is mainly basal (basal brain is involved)e
• Subarachnoid space is involved by the exudate (i.e. subarachnoiditis is present)Q
• Involvement is mainly of the leptomeninges i.e. Pia-arachnoid. (Duramater is usually spared.^Q

Answer is A (Tubercular meningitis):

Basal exudates, hydrocephalus, and ischemic infarcts are classical features of Tubercular Meningitis.

‘The triad of CT features (Thalamic infarction, Basal cistern enhancement, and Hydrocephalus) is diagnostic of Tubercular Meningitis’ —Journal of Indian Medical Association

Classical Radiological Features (CT/MRI) in Tubercular Meningitis

• Basal exudates Obliteration of Basal cisterns (Tubercular Exudates are primarily located in the vicinity of basal cisterns)
• Abnormal Leptomeningeal Enhancement (Usually most pronounced in the basal cisterns)
• Communicating Hydrocephalus (Usually communicating although non-communicating may also be seen)
• Ischentic / Vasculitic Infarcts (Basal ganglia and / or Internal capsule)
• Tuberculomas (Granulomas)

Ans. D i.e. Tuberculosis

Ans: C i.e. Raised protein, decreased glucose, increased lymphocytes

Conditions and CSF findings

• Subarachnoid hemorrhage presents with normal/slightly raised WBC, normal glucose and raised protein
• Viral meningitis presents with 10-2000 lymphocytes (normal 0-4 X 106/L), normal glucose and normal/increased protein
• Tubercular meningitis presents with 50-5000 lymphocytes, decreased glucose and increased protein
• Acute bacterial meningitis shows 1000-5000 polymorphs, decreased glucose and increased protein

Ans. D: Decreased glucose, increased proteins, increased lymphocytes

• Raised intracranial pressure
• Raised CSF protein (1-8 g/L)
• Lymphocytosis
• Low CSF glucose

Ans. Exudates seen in basal cistern