common in developing countries and also seen sporadically in
well-developed countries. Lately the incidence is on the increase, world
over, with the emergence of AIDS. About 60 % of cases are below the age of
20 years in developing countries. In developed countries the older people
are more commonly affected.
Tuberculomas may occur at any site intracranially. Infratentorial
presentation is more often seen in children. Intrasellar, CPangle, Optic
chiasma, intraosseous tuberculomas have been reported.
Invariably it is secondary from primary elsewhere, more commonly the
lungs, by hematogenous spread.
been suggested that the nature of the lesion, meningitis or a tuberculoma
would depend upon the number of bacilli, their virulence and the state of
immunity of the host.
Tuberculomas, more often evolve from tissue reactions, primarily cell
mediated, when the resistance of the patient is high. Meningitis is seen
in those with poor resistance.
20% of the patients have multiple lesions.
caused by the human strain. The bovine type is probably responsible for
less than 5 %, especially in Europe. Isolated cases due to atypical
mycobacteria are also seen.
Microscopically, there is central coagulative necrosis surrounded by
epitheloid cells, Langhans giant cells(as shown by the arrow in the
picture) and an admixture of lymphocytes and plasma cells. There may
be satellite lesions and perivascular infiltrations.
vary in size. When near the surface, some become adherent to
the dura, mimicking a meningioma. The usual type is a well-defined
avascular mass with multiple nodular extensions. It has a pale
yellowish, gritty, caseating central core with a crenated margin,
dispersed within an edematous brain, with a pseudocapsule of
compressed gliosed brain.
In its immature form it consists of small tubercles, some
with caseating or cystic centers, seen as grapelike clusters in a CT
Occasionally, there are well-localized lesions attached to
the dura with no calcification or caseation. They are called
Tuberculoma en plaque. They simulate an en plaque meningioma.
Tuberculous Abscess does not show
the granulomatous change, but has tubercle bacilli in the pus and
resembles a pyogenic abscess, starting as encephalitis and followed by
softening, leading finally to capsule formation.
Cystic Tuberculomas are rare and
have been reported with the cyst wall confirming the diagnosis.
Calcifications are seen in about
5% and do not suggest a healed or inactive lesion.
Tuberculuos Encephalopathy is
characterized by obvious edema with varying degree of perivascular myelin
loss, attributed to an allergic reaction to proteins liberated from the
lysed tubercle bacilli. It produces diffuse brain damage, especially in
Tuberculous meningitis in acute stage is associated with brain edema,
increased proteins in the CSF, poor absorption of the CSF and obstruction
to CSF flow. Later it is associated with tuberculous encephalopathy.In the
sub acute and chronic stage, there is endarteritis affecting the smaller
arteries and the large arteries at the base of the brain may get
compressed or occluded due to exudates resulting in multiple infarcts and
basal archnoiditis, which may cause hydrocephalus and compression of the
optic chiasma. Occasionally a tuberculoma may follow or be associated.
patients with a tuberculoma look better nourished unlike those with
tuberculous meningitis. The lesions present, like any other intracranial
SOL, with seizures and / or focal deficits depending on the location.
There may be features of increased ICT.
Suspicion is the first step in diagnosis. No diagnostic procedure either
singly or in combination will provide an unequivocal diagnosis.
erythrocyte sedimentation rate is often raised. The mantoux test is
negative mantoux does not rule out a tuberculoma. ELISA (enzyme linked
immunoabsorbent assay) tests of the serum and CSF may be help.
General investigations should include a search for a primary.
CT and MRI have helped
in early diagnosis and follow-up with medical management. Multiple lesions
are often seen.
There is no
specific image morphology.
In the early stages, there may be a
small area of increased attenuation surrounded by edema. There may be
contrast enhancing discs or rings with perilesional edema seen as ‘
fingerlike ‘ projections
Large rings with central lucency as seen in a pyogenic
abscess are also seen. A central nidus may give the appearance of the
so-called “target sign of Welch man”.
A large nodular mass with irregular
contours is a result of small rings and discs coalescing together.
complete hypo or isointensity or central hyperintensity with a
hypointense rim on T2 and isointensity and / or hypointensity on T1
weighted images. Lipids contribute to low signals on T2. There is
intense enhancement with Gadolinium.
It is essentially
medical and surgery may be indicated as an adjuvant to help in
When a tuberculous etiology is considered, a stereo
tactic biopsy is performed to confirm the diagnosis. Antituberculous
drugs are started along with steroids to reduce the perilesional
edema, if indicated clinically.
available anti tuberculous drugs rifampicin, isoniazid, pyrizanamide
and streptomycin are bactericidal and the former three penetrate the
blood brain barrier. They form the 1st line of drugs. After
initial treatment with three drugs for three months followed by any
two of the three or isoniazid and ethambutol for 12-15 months. A short
course is recommended for better compliance and claimed to be
However many prefer
18 months therapy.
In addition to stereotactic biopsy, surgery may be
indicated when there is
1) Life or
vision threatening increased ICT.
2) Failure of
response to medical therapy.
presentations such as subdural empyema
5) FNAC (fine
needle aspiration) for skull lesions
CT-hydrocephalus and abscess
MRI-Tuberculoma of the medulla
Total excision, once decided on surgery, is obviously the
procedure of choice in easily accessible lesions. There is no need for
heroic attempts for total excision. Simple evacuation of the pus from a
tuberculous abscess or liquefied caseous material may be adequate, either
stereotactically or by open surgery.
Ventriculo-peritoneal / atrial shunt may be required for persistent