|Home | About | Journals | Submit | Contact Us | Français|
Tuberculous brain abscess is a rare manifestation of tuberculosis of the central nervous system. We report a case of a 6-year-old girl with a pontine tuberculous abscess, who presented with fever and quadriparesis and recovered completely after stereotactic aspiration and antituberculous treatment with four drugs (isoniazid, rifampicin, pyrazinamide, and ethambutol). Tuberculous abscess was confirmed based on findings of magnetic resonance imaging, a positive tuberculin test, and the presence of acid fast bacilli in smear and culture of abscess aspirate.
Tuberculosis of the central nervous system (CNS), especially tuberculous meningitis, is one of the leading causes of mortality in children in India. The problem is further aggravated by the increasing prevalence of HIV infection in children.1,2 Tubercular brain abscess (TBA) is an uncommon manifestation of CNS tuberculosis. TBA may be unilocular or multilocular and resembles a pyogenic abscess clinically, radiologically and histologically.3 Patients may present with features of raised intracranial pressure and focal neurological deficit, depending on the site of the abscess.4 Magnetic resonance imaging of the brain is helpful in diagnosing TBA of the brain stem. We report a rare case of pontine TBA in a young girl who recovered completely with stereotactic aspiration and antituberculous treatment.
A 6-year-old girl was admitted with a history of fever for 1 month, hoarseness of her voice, and weakness in all four limbs for 15 days. Her mother was suffering from pulmonary tuberculosis and had been receiving antituberculous drug treatment for the previous 6 months. Examination of the patient revealed palsy of the IXth and Xth cranial nerve, brisk deep tendon reflexes in all four limbs with power of grade 0, bilateral positive Babinski’s response, and positive MacEwen’s sign. Pupils were bilaterally constricted and reacted to light. Fundus examination did not reveal papilloedema. Examination of the chest, cardiovascular and musculoskeletal system was unremarkable.
Investigations revealed: haemoglobin 13 g/dl, total leucocyte count 13100/cu mm, with 60% neutrophils, 36% lymphocytes and 4% monocytes. Erythrocyte sedimentation rate was 20 mm after the first hour. Liver function tests and renal function tests were normal. Cerebrospinal fluid study showed: cells 18/cu mm (all lymphocytes), protein 55 mg/dl, and sugar 51.4 mg/dl (blood sugar of 72 mg/dl). Chest radiograph and computed tomography (CT) scan of the cranium was normal. T1 weighted magnetic resonance imaging (MRI) scan showed a ring enhancing lesion measuring 2.8×2.1 cm in the pons with thin continuous smooth enhancing walls, well defined margins, internal fluid signal with surrounding oedema, and mass effect leading to expansion of the pons, suggestive of an abscess (fig 1). A tuberculin test was strongly positive (20×25 mm); HIV screening by enzyme linked immunosorbent assay (ELISA) was negative.
The differential diagnosis includes tuberculous abscess, pyogenic abscess, and pontine glioma. A relatively long clinical history and an enhancing capsule with a thick wall are suggestive of TBA. A pyogenic abscess, however, has a thin rim on contrast. The absence of surrounding brain oedema and gliosis and response to antituberculous treatment excludes the diagnosis of glioma.5 The tuberculous origin can be further supported by demonstration of acid fast bacilli in culture or staining of pus or wall.
Stereotactic aspiration of the abscess was done on day 6. AFB staining of aspirated pus showed acid fast bacilli and the same from mycobacterial culture. Aerobic and anaerobic culture was sterile, and culture for fungi was also negative. The patient was finally diagnosed with a pontine tuberculous abscess with quadriparesis and treated with a four drug antitubercular regimen (isoniazid, rifampicin, pyrazinamide and ethambutol) and prednisolone. On postoperative day 7, the patient started showing improvement in power and disappearance of the clinical features of cranial nerve palsies. Her parent was advised to continue physiotherapy at discharge.
The patient had grade 4 power in all four limbs and no cranial nerve palsy at 1 month follow-up. Antituberculous treatment was continued and prednisolone was tapered over the next 2 weeks and stopped thereafter. Subsequent follow-up at 2, 6, 9 and 12 months showed no neurological deficit with normal serum alanine transaminase (ALT) and aspartate transaminase (AST) values. Antituberculous treatment was given for 12 months in accordance with the recommendations of the Indian Academy of Paediatrics guidelines for treatment of central nervous system tuberculosis.
TBAs are very rare. Fifty-nine cases of tuberculous abscess have been reported in the world literature, but only 18 cases fulfil the criteria laid down by Whitener.3 It is not known why abscesses form instead of the usual tuberculoma, which comprise approximately 20% of all intracranial space occupying lesions in children. Several factors such as the state of the body’s immunity, dose of infecting agent, nature of the involved tissue, and antituberculosis treatment perhaps determine the type of tissue reaction.2,3 It usually occurs due to haematogenous spread of Mycobacterium tuberculosis from elsewhere, but can also occur via lymphatic spread from the cervical nodes. Abscess walls are usually devoid of epithelioid and giant cells, which are characteristic of tuberculoma, but if present are not in the form of organised follicles.4 The abscess wall is composed of a necrotic inner surface and a fibrous outer surface associated with an inflammatory reaction.3,4 Our patient had a relevant history, a positive tuberculin test, and acid fast bacilli in the aspirate of the pontine abscess.
The presentation of tuberculous abscess is acute, as in our patient. The locations of TBA are mainly supratentorial and rarely in the cerebellum. Patients usually present with focal neurological signs and are associated with histological and laboratory evidence of tuberculosis. Cerebrospinal fluid examination may show pleocytois with increased protein, and PCR may be positive for mycobacteria in a good number of cases.
CT shows a hypodense lesion surrounded by an enhancing ring.6 There may be associated surrounding oedema. The clinical picture of both types of abscesses—that is, pyogenic and tuberculous—is similar. Abscesses are present frequently in the supratentorial compartment, with focal neurological deficit, fits, and altered level of consciousness. Papilloedema and headache are more common in pyogenic than in tuberculous abscesses. Both types of abscesses produce the ring lesion with peripheral oedema in the CT scan.6,7 The lower attenuation value in the centre of the lesion than in the brain tissue may be indicative of the presence of pus. Surrounding brain oedema and low gliosis may resemble low grade glioma.6 A majority of the TBAs have a thicker wall compared with pyogenic abscesses because of their slower evolution, but some pyogenic abscesses may have a thick capsule if they develop over a longer period. Multiplicity is more common in pyogenic than in cold abscesses. Most of the time it is not possible to make a preoperative diagnosis. Intraoperative smear examination of the aspirated pus is the easiest way to determine the diagnosis so that proper chemotherapy can be instituted immediately, thereby minimising postoperative mortality and morbidity as in our case. Acid fast bacilli should be demonstrated on Ziehl-Neelsen stain.
Treatment options include simple puncture, continuous drainage, fractional drainage, repeated aspiration through a burr hole, stereotactic aspiration, and total excision of the abscess. Total excision is usually required in multilocular non-communicating and thick walled abscesses. The development of fulminant tubercular meningitis is sometimes problematic following surgical stereotactic aspiration.8
Competing interests: None.
Patient consent: Patient/guardian consent was obtained for publication.