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Neuroradiology Case of the Week

Case 376

January 2009

Rajiv Mangla, MD and Per-Lennart Westesson MD, PhD, DDS

Clinical Presentation: Patient presented with progressive right lower extremity weakness and numbness.

Imaging Findings: A well-defined hyperintense lesion is seen in the left periventricular white matter. On close inspection of the lesion, there are multiple concentric rings within the lesion consistent with zones of demyelination (Figs. 1 & 2). The lesion shows enhancement on post-contrast images with depiction of concentric rings (Figs. 3A & B). Few other lesions are also seen in the periventricular white matter on FLAIR images (Fig. 4). Diffusion is not restricted in most of the portion but along the margins, there is mild restriction could be suggestive of active inflammation along the margin (Figs. 5A & B).

Diagnosis: Baló's concentric sclerosis

Discussion: Balo concentric sclerosis is an uncommon demyelinating disorder, believed to be a variant of multiple sclerosis. It is usually seen in young adults (age range, 4–56 years) Patients usually present with symptoms of an acute/subacute onset those progresses over a period of weeks to months, suggesting a space-occupying lesion of the brain.
     The characteristic pathologic findings are alternating rings of myelin preservation or remyelination and myelin loss, consistent with demyelination. These lesions could be seen in cerebral hemispheres, cerebellum, brain stem, spinal cord, and optic chiasm. Imaging features pathognomonic for Balo concentric sclerosis include alternating rings of demyelinated and myelinated white matter seen on T2 weighted images with concentric ring enhancement on T1 weighted images after post-administration of gadolinium [1,2]. The underlying pathophysiological explanation for the concentric rings seen in cases of Balo concentric sclerosis remains unknown, but it is likely that the various rings represent different stages of demyelination. Diffusion is usually not restricted as seen in the classical cases of multiple sclerosis , however focal areas of restricted diffusion can be seen in during active phase [3]. MR spectroscopy usually demonstrates an increased choline peak and a decreased N-acetyl with lactate might be seen in few cases. Aspartate peak has been reported in one reported case of Balo concentric sclerosis [].
     Clinical differential diagnosis includes acute disseminated encephalomyelitis, multiple sclerosis, neoplasms, and infections such as abscesses. However, the typical concentric pattern on MR images as described above, which is similar to other reports, is highly suggestive of BCS. The studies have confirmed that patients who were diagnosed as having this entity, based on a characteristic MR appearance, have subsequently been proved to have the typical pathologic changes of BCS at autopsy or biopsy. Therefore, MR imaging should be considered the diagnostic procedure of choice in such cases.

References:

1. Karaarslan E, Altintas A, Senol U, et al. Baló's concentric sclerosis: clinical and radiologic features of five cases. AJNR Am J Neuroradiol. 2001 Aug;22(7):1362-7. [PubMed]
2. Caracciolo JT, Murtagh RD, Rojiani AM, Murtagh FR. Pathognomonic MR imaging findings in Balo concentric sclerosis. AJNR Am J Neuroradiol. 2001 Feb;22(2):292-3. [PubMed]
3. Kavanagh EC, Heran MK, Fenton DM, et al. Diffusion-weighted imaging findings in Balo concentric sclerosis. Br J Radiol. 2006 Jul;79(943):e28-31. [PubMed]
4. Kim MO, Lee SA, Choi CG, Huh JR, Lee MC. Balo's concentric sclerosis: a clinical case study of brain MRI, biopsy, and proton magnetic resonance spectroscopic findings. J Neurol Neurosurg Psychiatry. 1997 Jun;62(6):655-8. [PubMed]