REVIEVV ARTICLE Magnetic resonance features of intracranial tuberculosis in children S Andronikou MBBCh (W/ts), FCRadO/ag, FRCR (Lond) E Kader MBChB CJWelman MBChB Department of Paediatric Rsd/ology, Un/vers/ty of Gape Town and /nstttute of Child Hes/th, Red Cross Children s Hosplts/, Rondebosch, Cape Town Corresponding author Or Sawas Andronlkou DeparlmBnt of PB8diatr/c RadIology, Univ8rsIty of Cape Town and JnstJtuts of Ch/Id HeaJth, Rad Cross ChI/dr9n's HospItal, RondBbosch, Cape Town, 7700 Te/: (021) 658-5422. Fax: (021) 658-5101. E-msil: docsaV@mweb.co.za Abstract Accepted as a poster for the 37th Conference of the European Society of Paediatric Radi%gy, Lisbon, Portugal (22-26 May 2000) Intracranial tuberculosis in children is seen as either parenchymal tuberculous lesions or tuberculous meningitis (TBM). This article demonstrates the MR features of TBM and the two varieties of tubercu lous (TB) granulomata. Gummatous granulomata (tuberculomata) comprise 90% of presenting intracranial TB lesions. They have a characteristic low signal on T2-weighted sequences that differentiates them from other commonly encou ntered ri ng- enhancing lesions such as neurocysticerci. TB abscesses are very rare and have the same 10 SA JOURNAL OF RADIOLOGY· February 2001 features as pyogenic abscesses. Features of TBM include hydrocephalus, basal meningeal enhancement and basal ganglia infarctions. Introduction The Western Cape has one of the highest incidences of intracranial TB in the world. This may take the form of TBM where the patient presents with a decreased level of conscious- ness, cranial nerve palsies and hemi- plegia.' In contrast, intracranial granulomata usually manifest with seizures.' This article demonstrates the MR imaging features of these forms of intracranial TB. Discussion In areas endemic for intracranial TB, neurocysticercosis may also be endemic/ and is regarded as a more common cause for childhood seizures. The management of these two enti- ties differs and it is therefore crucial to differentiate between them,' espe- cially as current anti- TB therapy has significant side-effects. Not only is MRI more sensitive in detecting le- sions, but it is also able to differenti- ate the more common type of TB granuloma from a neurocysticercus. Tuberculomata (gummatous granulomata) comprise approxi- mately 90% of intracranial TB le- sions and are hypo intense on T2- weighted sequences'? (Figure 1). Neurocysticerci, in contrast, are T2 hyperintense." The T2 imaging char- acteristics are, however, not pathogno- monic of TB, as syphilis' and densely cellular neoplasms such as germinomas and P-NETs (medulloblastomas) can topage11 mailto:docsaV@mweb.co.za Magnetic resonance features of intracranial tuberculosis in children from page 10 Figure 1: Gummatous granuloma/tuberculoma a. TI-weighted MR shows a left-sided cerebellar lesion that is isointense to brain b. T2-weighted Image shows a lesion that is hypointense to brain and Is surrounded by high-signal oedema c. TI-welghted post-gadolinium MR shows ring enhancement of the lesion 11 SA JOURNAL OF RADIOLOGY. February 2001 Figure 2: Tuberculous abscess also be hypointense on T2-weighted images," The latter entities, however, can frequently be excluded, as they have additional imaging characteristics and do not show typical ring enhance- ment with gadolinium. TB abscesses are relatively rare (Figure 2). Pathologically they contain liquefied or caseous material that dif- ferentiates them from the gummatous material seen in tuberculomata (gum- matous granulomataj.ê+' They are inseparable on MR imaging from neurocysticerci, cystic neoplasms and fungal and pyogenic abscesses, which are all T2 hyperintense.I" Granulomata may occur in clusters or may exist simultaneouslyin multiple sites. S When granulomata abut the meningeal surface, they may rupture into the me- ninges and cause TBM2 (Figure 3). The classic triad of TBM is basal meningeal enhancement, hydrocepha- lus and basal ganglia infarction.' The most consistent finding in TBM is hy- drocephalus.l-" Basal meningeal en- hancement is often very pronounced (Figure 4a), but can also be seen in bac- terial meningitis and may sometimes be absent in confirmed cases of TBM.! Angiitis of the small vessels passing through the inflamed meninges can lead to infarctions in the basal ganglia region (Figures 4b and 4c). It is these infarcts that determine the morbidity and mor- tality associated with TBM.u,s MRI is more sensitive than CT in detecting basal meningeal enhancement as well as the infarctions. The infarcts have a low signal on Tl and are T2 hyperintense, while tuberculomata are isointense on Tl and hypointense on T2, Tuberculomata are only found in 10% of cases ofTBM.2 Conclusion MRI can differentiate TB granulomata from neurocysticerci and other ring-enhancing lesions. This has a significant impact on therapy and avoids topags 12 Magnel ic: resona nee feéllLI res of inlracranial tuberculosis in children frampage 11 Figure 3: Clusters and multiple granulomata: Clusters of granulomata are seen abutting the basal meninges the unnecessary use of potentially harmful medication. The detection of TBM and associated infarcts is im- proved. In our population, where the inci- dence of TB is very high, the clinical suspicion of intracranial TB, in the ap- propriate clinical setting, is always high. It is important to note that there is no single diagnostic feature of in- Figure 4: TBM and its complications a. T1-welghted post-gadolinium MR demonstrates basal meningeal enhancement, dilated temporal horns indicating hydro- cephalus and a cerebellar tuberculoma b. T2-weighted image demonstrates hydrocephalus and areas of infarction in the right basal ganglia region 12 SA JOURNAL OF RADIOLOGY. February 2001 tracranial TB and the diagnosis should be based on a combination of imaging characteristics, clinical findings and laboratory data.' Acknowledgements We would like to thank Helen Tomazos and Medical Graphics for their help in the preparation of this article. References 1. Schoeman J, Hewlett R, Donald P. MR of childhood tuberculosis meningitis. Neuroradiology 1988; 30: 473-477. 2. Jamieson DH. Imaging intracranial tuberculosis in childhood. Pediair Radial 1995; 25: 165-170. 3. Gupta RK, Pandey R, Khan EM, Mittal P, Gujral RB, Chhabra DK. 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