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|Year : 2011 | Volume
| Issue : 4 | Page : 597-600
Balo's concentric sclerosis involving bilateral thalami
Farheen Badar1, Shah F Azfar2, Ibne Ahmad1, Sanna Kirmani1, Muddassir Rashid3
1 Department of Radiodiagnosis, J.N. Medical College, A.M.U, India
2 Firoz Specialist Hospital, Aligarh, Uttar Pradesh, India
3 Medical Imaging, Royal Children Hospital, Melbourne, Australia
|Date of Submission||22-Apr-2011|
|Date of Decision||26-Apr-2011|
|Date of Acceptance||17-Jun-2011|
|Date of Web Publication||30-Aug-2011|
Department of Radiodiagnosis, J.N. Medical College, A.M.U, Medical Road, Aligarh - 202 002, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
Balo's concentric sclerosis (BCS) is a rare inflammatory demyelinating disease of central nervous system, pathologically chracterized by alternate bands of demyelination and preserved myelin tissue. Before the era of magnetic resonance imaging (MRI), most cases of BCS were diagnosed on postmortem examination. MRI allows for noninvasive diagnosis by demonstrating characteristic changes which closely parallels the histopathological features of BCS. We report a case of 26-year-old female with BCS involving bilateral thalami, with typical MRI appearance.
Keywords: Balo′s concentric sclerosis, magnetic resonance imaging, thalami
|How to cite this article:|
Badar F, Azfar SF, Ahmad I, Kirmani S, Rashid M. Balo's concentric sclerosis involving bilateral thalami. Neurol India 2011;59:597-600
| » Introduction|| |
Balo's concentric sclerosis (BCS) is a rare and fulminant form of idiopathic inflammatory-demyelinating diseases of central nervous system (CNS) and is considered to be a variant of multiple sclerosis (MS).  It is characterized pathologically by concentric lesions of alternating demyelinated and myelinated bands in the white matter. Magnetic resonance imaging (MRI) demonstrates these bands as concentric pattern and thus allows differentiation from other pathology. Lesions of BCS have been reported in spinal cord, cerebellum, brain stem, optic chiasm, and cerebral hemispheres. ,, Involvement of thalami in BCS is rather unusual. We present a 26-year-old female with BCS involving bilateral thalami, with characteristic MRI appearance.
| » Case Report|| |
A 26-year-old female presented with history of sudden-onset right side hemiparesis and impairment of consciousness. Prior to the day of admission, she had acute-onset severe headache, irritability, and diffuse pain all over the body. There was no history of any infection, or vaccination preceding the symptoms. Urgent plain computed tomography of brain revealed hypodense lesion in bilateral. Over next few hours, her mental status worsened and she had decorticates posturing to painful stimuli, and planter response was bilateral extensor. Brain MRI performed next day revealed concentric pattern of lesion in the bilateral thalami with characteristic alternating hypointense and hyperintense bands on T1-weighted [Figure 1]a and b and T2-weighted [Figure 1]c associated with perilesional-edema. These patterns were best seen in post-contrast images with whorl-like enhancement [Figure 2]a-c. Deep venous sinuses showed normal signal void on conventional spin echo sequence with no filling defect on MR venography. Cerebrospinal fluid examination revealed mild pleocytosis (35 white blood cells/ml), normal glucose, and elevated protein (263-mg/dl). Oligoclonal bands were negative, and the immunoglobulin G (IgG) index was 0.7 (normal <0.8). Peripheral blood counts were normal. Extensive serologic studies including herpes simplex virus type 1 and 2, varicella-zoster virus, HIV type 1 and 2 were negative.
|Figure 1: (a) Axial unenhanced T1-weighted image (b) Sagittal unenhanced T1-weighted image showing a concentric ring pattern of lesion in the bilateral thalami. (c) Axial T2-weighted image showed hyperintense signal in the bilateral thalami with alternating hypointense and hyperintense concentric rings with surrounding white matter edema bilaterally|
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|Figure 2: Postcontrast T1-weighted (a) axial, (b) sagittal, and (c) coronal image showed striking concentric enhancement of bilateral thalami lesion|
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The patient received intravenous methylprednisolone 1000 mg daily for 5 days, and was kept on a maintenance dose of prednisolone 60 mg/day for next 15 days. Her mental status improved with marked improvement in her weakness. Dose of prednisolone was gradually reduced to 30 mg/day. At 12-month follow-up, there were no further relapses and she has started performing some of the routine work with minor assistance. A repeat follow-up MRI was advised; however, patient refused for it.
| » Discussion|| |
BCS is considered as rare and severe variant of MS.  Most patients are young adults in their third and fourth decades of life, and it is relatively more common in males. ,, It shares the basic pathologic similarity to multiple sclerosis, with the exception of an alternating lamellar pattern of demyelinated white matter and well-preserved white matter.  BCS and MS like lesions are also known to coexist in same patient.  Clinical course of BCS is highly variable. The common clinical features include headache, aphasia, hemiparesis, sensory disturbance, cognitive or behavioral dysfunction, andseizures. Most reported cases of BCS have been reported from Asian countries, suggesting the role of genetic and environmental factors. ,,,,,, Clinical profile, MRI features, and outcome of patients with BCS reported from India are summarized in [Table 1]. Coexistence of BCS and oligodendroglioma in the same patient has also been reported.  Traditionally, it has been considered to have a rapidly progressive fatal course, but with advent of MRI, mild and benign course has also been recognized. ,, The cases reported by Karaarslan et al.  and Gu et al.  had benign clinical course without relapse. Our patient had also a benign course with no relapse in the 12-month follow-up. Before the era of MRI, many cases with mild clinical presentation might have been missed.
|Table 1: Clinical characteristics, MRI findings, and outcome of BCS cases from India|
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The diagnosis of BCS in the past was made on autopsy or histopathologically in the presence of characteristic CNS lesions consisting of concentric rings of demyelination alternating with myelinated white matter. Recently, however, many patients are being diagnosed solely on the basis of characteristic MRI appearance without the need of biopsy and histopathological confirmation. ,,,, Characteristic MRI features include alternating bands of low and high signal in white matter seen on T2-weighted images and the presence of concentric ring enhancement on postgadolinium T1-weighted images.  Mass effect and edema can also occur.  Diffusion-weighted findings with central T2 shine through and peripheral restricted diffusion has also been described.  In our case, the concentric pattern was seen on all MR sequence and best demonstrated on post gadolinium scan similar to previously reported cases.
The exact neuropathological basis of BCS lesion is not well understood and has been a topic of debate. It has been proposed that these alternating bands may represent areas of demyelination and preserved myelin tissue. The reason for concentric demyelination in this variant of MS is unclear. Recently, it is proposed that demyelination in these lesions resemble hypoxia-like tissue injury. Proteins involved in tissue preconditioning are expressed at the edge of the lesion and this may explain the pattern of the lesions in BCS.  This is supported by the diffusion-weighted finding with restricted diffusion in the periphery of the lesion. 
Lucchinetti et al.  classified active MS lesions immunopathologically into four distinct subtypes: (1) patttern I and pattern II shows typical perivenular distribution of lesions and prominent lymphocyte and macrophage infiltration. Pattern II, however, also shows immunoglobulin deposition and complement activation; (2) pattern III shows unusual features where demyelination is not centered on inflamed vessels, instead a rim of preserved myelin is observed around the vessels. Also it shows signs of distal oligodendrogliopathy with features of apoptosis; and pattern IV lesions show massive oligodendrocyte degeneration in the periplaque white matter. Balo's concentric sclerosis lesion fits into pattern III (distal oligodendrogliopathy), characterized by microglial activation and oligodendrocyte apoptosis.
Corticosteroids have been shown to be effective in treating the neurological deficits associated with BCS.  Plasma exchange is reserved for steroid-resistant acute attacks of CNS demyelination.  Pathological subtype of MS may be the factor that predicts the response to plasma exchange therapy and only patients with evidence of antibody and complement deposition, i.e., pattern II, are likely to respond to plasma exchange therapy. 
Bilateral thalamic involvement is rare in BCS. Experience with this patient suggests that BCS should be considered in the differential diagnosis, especially in the presence of typical MR features. MRI allows for early in-vivo diagnosis, so that early and appropriate therapy could be commenced.
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