INTRODUCTION Granulomatous inflammation is a distinctive ...

PCR assay
The advent of detection procedures for the amplification of fragments of mycobacterium DNA,
called polymerase chain reaction (PCR), has turned attention away from serological techniques.
The PCR test has been assessed against both culture and ELISA for antimycobacterial antibodies
in the diagnosis of TBM (Kox et al., 1995). It detected 75% of 20 cases of highly probable TBM,
57% of 7 probable cases, and 43% of 7 possible cases. ELISA detected 55% of highly probable
and 29% each of the other two categories (Shankar et al.,1991). The sensitivity of PCR was 48%
with a specificity of 100%, whereas culture alone had a sensitivity of 39% and a specificity of
100% (Kox et al.,1995). Furthermore, the PCR test was positive in 90.5% (19 out of 21) of TBMsuspected
patients (Liu et al.,1994) and 100% sensitive in HIV-infected patients (Folgueira et
al.,1994). Inspite of this, PCR is inappropriate for use in many places in the developing world and
current studies suggest that PCR does not solve the global diagnostic challenge set by TBM
(Thwaites et al., 2000).
Neuroimaging
Radiological diagnostic methods such as computer tomography (CT) and magnetic resonance
imaging (MRI) have greatly enhanced the diagnostic accuracy of TB of the CNS, but they are still
not pathognomic for the disease (Muralidhar, 2004).
In TB meningitis CT or MRI of the brain may reveal thickening and intense enhancement of