Calil Kairalla
Farhat
Federal
University of Sao Paulo - Brazil
Tuberculosis remains the most important infectious disease
in the world, specially in developing countries, where it is also one of the
biggest Public Health issues under discussion.
Since there’s been a lack of
attention to this disease from the past decades, the number of cases has been
increased around the world, which brought this problem to a new status of
re-emerging disease by WHO. The increasing numbers of AIDS have contributed a
lot to the current situation, and because of that even the classification as a
persistent disease is appropriate.
The incidence rates of
tuberculosis in American countries varies from 7-9 per 100.000 (Canada, Cuba,
Trinidad-Tobago) to 100-350 per 100.000 (Honduras, Bolivia).
Tuberculous meningitis is
the most severe presentation of tuberculosis and occurs in children between 3
months and 10 years of age, usually from 3 months to 3 years of age.
It starts from a primary
complex, frequently pulmonary, and then there is hematogenous dissemination,
producing small caseous foci situated in the brain or meninges. The rupture of this foci causes
discharge of tubercle bacilli directly in the subarachnoid space. A gelatinous
exudate is developed in the pia-arachnoid, in the brain, infiltrates the walls
of meningeal arteries and veins – with inflammation, caseatiion and obstruction
– and extends to small vessels into the cortex, leading to infarcts.
The interference of the
inflammatory process with the normal flow of the cerebrospinal fluid and with
its absorption, and the predilection for the base of the brain explains the
symptoms and the frequent involvement of the optic chiasm and the third, sixth,
and seventh nerves.
The
clinical course of the disease can be divided into three stages, each one with
a duration of nearly two weeks.
1.
apathy, personality change, anorexia,
irritability and some fever (temperatures not very elevated).
2.
signs and symptoms of central nervous
system involvement, demonstrating meningeal damage: drowsiness, stiff neck,
inequality of the pupils, vomiting, convulsions and signs of cranial nerves
involvement (III, VI, VII).
3.
Signs of severe neurologic damage
(decerebration, decortication), with irregular pulse and respirations,
opisthotonus, coma.
Important aspects
for the diagnosis are:
-
history of contact with a person with tuberculosis
-
tuberculin skin test – for children who didn’t receive BCG vaccination.
-
Chest roentgenogram
-
Cerebrospinal fluid analysis, with often the following findings:
increase in cellularity – 50
to 500 white blood cells per mm3, with polymorphonuclear leucocytes
predominant
decreased glucose level
.high concentrations of protein content (sometimes it can be observed the
development of a pellicle on standing fluid)
spinal fluid culture –
results after only 30 to 60 days, with less than 50% of positivity
Other valuable diagnostic
methods:
gastric wash culture
enzyme-linked immunosorbent
assay (ELISA) – for IgG and IgM antibodies to purified protein derivative (PPD)
and bacille Calmette-Guérin (BCG) – sensibility of 90% and specificity of 89%.
computed tomography
magnetic resonance
imaging
polymerase chain
reaction (PCR)
As for evolution of the cases, the most
important aspect is still “the earlier diagnosis the better prognosis” well
know principle. Treatment must start promptly after diagnosis, and patients
need to be followed closely, since the long term basis of therapy frequently
leads to treatment disruption.
Very young age, the
occurrence of convulsions, hydrocephalus and vasculitis are generally poor
prognostic factors.
Long-term sequelae of
this disease are more frequent and severe if diagnosis and treatment delay:
blindness, deafness, intracranial calcification, diabetes insipidus, obesity,
paraplegia, and mental retardation.