|Vol. 4, Issue 2, Article 1||Saleem, S.|
NBD can be mistaken for other diseases of the central nervous system with multi-focal presentations such as multiple sclerosis (MS) and systemic lupus erythematosus (SLE), especially in the absence of systemic manifestations of BD (7). In the acute phase of NBD, large confluent lesions in the brainstem-thalamic-basal ganglia region are highly suggestive of the disease and can help to differentiate it from MS and SLE (26). In SLE, the lesions predominantly involve the sub-cortical white matter of the cerebral hemispheres and less frequently involve the basal ganglia or brainstem (Fig 27) (26). In MS, the lesions are predominantly periventricular, with infrequent involvement of the basal ganglia and internal capsule (Fig 28) (62). Moreover, brain stem lesions in MS are usually small, even in the acute stage, and seen along the floor of the fourth ventricle or anteriorly in the pons. This distribution contrasts with involvement of the central part of the pons in NBD (21). Spinal cord involvement in NBD tends to be extensive, whereas it rarely extends over more than two vertebral segments in MS (22). Linear high signal intensity in T2-weighted images along the internal capsule is highly suggestive of parenchymal NBD and is seen less frequently in other diseases of the CNS (7). High signal intensity along pyramidal and other fiber tracts is another finding seen in NBD (22).
White matter lesions seen in the chronic phase of parenchymal NBD can be difficult to differentiate from MS, SLE or other vasculitic or infectious CNS lesions (22). Cerebral white matter lesions are most commonly periventricular in MS, subcortical in SLE but they are both periventricular and subcortical in NBD. MRI has low (40%) specificity for the diagnosis of chronic NBD, unless accompanied by localized atrophy of the brainstem, in which case it can be up to 100% specific. The latter is very unusual in MS and SLE (26).
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