The Neuroradiology Journal 21: 166-172, 2008
www. centauro. it
Magnetic Resonance Imaging in Balo’s Concentric Sclerosis. A Case Report
A.Y.T. AL-TURKOMANI, T. J.E. MUTTIKKAL, A. BEN-NAKHI Department of Radiology, Mubarak Al-Kabeer Hospital; Hawally, Kuwait
Key words: Balo’s concentric sclerosis, magnetic resonance imaging, diffusion weighted imaging, magnetic resonance spectroscopy, multiple sclerosis
SUMMARY – Concentric high signal intensity zones on T2-weighted magnetic resonance images of brain strongly suggest Balo’s concentric sclerosis (BCS), a rare but recognized variant of multiple sclerosis. Differentiating BCS from multiple sclerosis or neoplasm can be difficult clinically. The pathognomonic MRI appearance can dramatically influence the course of the disease, allowing earlier diagnosis and therapy of the disease which was once considered to have an invariably fulminant and fatal course.
Introduction
Case Report
Balo’s concentric sclerosis (BCS) is generally considered to be a rare variant of multiple sclerosis. It may present clinically similar to multiple sclerosis, or with mild cognitive impairment without frank dementia, or with altered behavior and focal neurological deficits. Historically the diagnosis was made post-mortem or histopathologically by biopsy. However recent literature suggests that BCS may show characteristic radiological features that aid in antemortem diagnosis 1. The following case further confirms this impression. The differentiation between demyelinating lesions and CNS tumors such as gliomas presenting as solitary lesions has always been difficult. The pathognomonic magnetic resonance imaging (MRI) appearance of BCS together with magnetic resonance spectroscopy (MRS) helps to reach the definitive diagnosis. The initial reports of BCS suggested that the disease is rapidly progressive and fatal 2, but there are studies showing the efficacy of corticosteroids against neurological deficits associated with BCS 3. Therefore, early MR imaging influence the course of the disease, by aiding prompt diagnosis and therapy of BCS patients.
A 24-year-old man without any significant medical history or prodromal events presented to the emergency room with acute onset of left-sided weakness and numbness. There was focal neurological deficit, with grade 0 out of 5 power in the left arm and grade 2 out of 5 power in the leg, in addition to hypoesthesia. The patient was admitted with a presumptive diagnosis of stroke. MRI of brain done three days later showed a concentric area of abnormal signal intensity in the white matter adjacent to the right lateral ventricle on T2-weighted images and fluid attenuation inversion recovery (FLAIR) images (figure 1 A,B). T1-weighted images did not show any significant mass effect (figure 1C). Faint inhomogeneous contrast enhancement of the lesion was noted with gadolinium (figure 1E). Diffusion weight images showed circular rings of hyperintensity similar to the T2-weighted images (figure 1D). Apparent diffusion coefficient (ADC) images generated off-line demonstrated a peripheral zone of restricted diffusion around a central nidus of T2 shine through and unrestricted diffusion (figure 1F). This zone of restricted diffusion extended beyond the border of the lesion appreciated in T2-weighted images.
166
A.Y.T. Al-Turkomani
CT scan of abdomen and pelvis was done as a probability of metastases was considered; the scan was normal. The following laboratory tests had normal results: Lyme serology, HIV, lupus anticoagulant, Sjogren’s antibodies, homocysteine levels, antiscleroderma 70, antiSmith, anti-Jo-1 and anticardiolipin antibodies, erythrocyte sedimentation ratio, CMV and Ebstein Barr virus antibodies and blood cultures. Lumbar puncture revealed normal cell counts, glucose and total protein levels. Myelin basic protein levels were elevated at 9 ng/ml (normal range 0-4 ng/ml), but the immunoglobulin synthesis rate was normal and oligoclonal bands were absent. The patient was started on high dose methyl prednisolone, as an inflammatory process/demyelination was suspected. There was only minimal improvement and the patient was transferred to tertiary care center 12 days after the onset of symptoms for further evaluation and management. At the time of transfer the patient had grade 0 out of 5 power in the left arm and grade 2 out of 5 power in the left leg. Repeat MRI scan of brain done approximately two weeks after the onset of initial symptoms revealed few changes in the right periventricular lesion, with concentric rings appearing more conspicuous in T2 and FLAIR imaging. Single voxel magnetic resonance spectroscopy (MRS) showed normal choline peak, decreased N-acetyl aspartate (NAA) peak (reflecting neuronal loss) and elevated lactate doublet peak (consistent with impaired aerobic metabolism) within the lesion compared to the corresponding region in the contralateral hemisphere (figure 2). The presentation and neuroimaging findings were consistent with the diagnosis of Balo’s concentric sclerosis (BCS). Steroid treatment was continued and there was an improvement in the patient’s symptoms during the next few days. About three weeks after his initial presentation, the patient was discharged for rehabilitation on a tapering oral steroid regimen. Follow-up five months after initial presentation showed a significant improvement, with grade 4 out of 5 power in the left arm and leg. However the patient was having occasional paresthesia on the right side. Repeat MRI showed significant resolution of the lesion in the right periventricular region. There was a new lesion on the left periventricular region with perilesional edema. The lesion showed a concentric appearance on T2-weighted images (figure 3A), with discontinuous concentric ring-like enhancement on post-contrast T1 images (figure
Magnetic Resonance Imaging in Balo’s Concentric Sclerosis
3B). The concentric nature of the lesion was best visualized in T2-weighted images (figures 3A, 4A) and was not obvious in FLAIR (figure 4B), proton density (figure 4C) or T1-weighted images (figure 4D). Discussion Balo’s concentric sclerosis is considered to be a rare variant of multiple sclerosis. Clinical presentation may be similar to multiple sclerosis, or with mild cognitive impairment without frank dementia, or with altered behavior and focal neurological deficits. Historically, the diagnosis was made post-mortem or histopathologically by biopsy. The first antemortem diagnosis by biopsy was reported by Garben et Al in 1986 4 and the first reported case of antemortem diagnosis of Balo’s concentric sclerosis based solely on the MRI findings was by Spiegel et Al in 1989 5. In contrast to multiple sclerosis, BCS is believed to run a fulminant and fatal course 6,7. However with MR imaging, BCS can be identified earlier when the characteristic pattern of demyelination is seen. As a result, early therapy can be instituted to provide symptomatic relief and slow down the progression of inflammatory demyelination. There are case reports of clinical improvement after the administration of corticosteroids in the literature 3,8. Our case demonstrates the unusual multiphasic nature of the illness, well demonstrated by the follow up MRI which shows resolution of the lesion on the right, and appearance of a new active lesion with pathognomonic imaging features on the left. The characteristic MR appearance when present, suggests the diagnosis of BCS as seen in our case where the T2-weighted and the FLAIR images showed separate concentric zones of demyelination (figures 1A, B, 3A, 4A). T1-weighted images following administration of gadolinium demonstrated discontinuous rings of enhancement at sites of increased bloodbrain barrier permeability and inflammation responsible for demyelination in a characteristic concentric pattern (figure 3B). The imaging findings correspond to the characteristic pathological findings of alternating rings of myelin preservation or remyelination and myelin loss, which appear as concentric pattern streaks alternating between light and shade, resembling a tree trunk cross-section or onion rings 9,10. Various theories have been proposed to explain the pathogenesis of BCS and the radio167
Magnetic Resonance Imaging in Balo’s Concentric Sclerosis
A.Y.T. Al-Turkomani
Figure 1 A) Axial T2-weighted image and B) axial FLAIR image showing a right periventricular lesion with concentric bands of variable hyperintensity. C) Axial T1-weighted image showing absence of mass effect. D) Diffusion-weighted image and F) apparent diffusion coefficient (ADC) image showing restricted diffusion in periphery with a central nidus of unrestricted diffusion and T2 shine through. E) Axial post-contrast T1-weighted image showing faint, inhomogeneous enhancement.
graphic findings. Early researchers suggested that the alternating zones of myelinated and demyelinated white matter reflected a vascular obstructive process resulting from embolization of lipid particles produced at primary multiple sclerosis lesions 7. More recent reports dismiss the notion of remyelination and suggest that the regions of myelination are more indicative of myelin breakdown at an earlier stage of development than seen in frank demyelination. These same reports highlight the limited supportive evidence for the role of toxins and infectious/inflammatory agents in the pathogenesis of BCS 11. There are studies which suggest a synchronous origin of the concentric rings, while there are studies against it 12,13. Our study showed enhancement of the concentric rings consistent with synchronous demyelination which is explained by the hypotheses of concentric de168
myelination by self-organization which states that the microglia self-organizes into concentric rings upon chemotactic stimulation 14. Tissue preconditioning has also been proposed as a mechanism to explain the concentric lesions 15. Diffusion weighted imaging findings in Balo’s concentric sclerosis have been described in two case reports 16,17, which demonstrated the peripheral zone of restricted diffusion as seen in our case. This has been attributed to rapid demyelination. Inflammation and blood brain barrier beak down, the initiating process in demyelination may account for the restricted diffusion 16. The low spatial resolution of diffusion weighted images may account for the absence of demonstrable inner zones of restricted diffusion in cases with active demyelination in inner zones. MR spectroscopic studies have shown decreased N-acetyl aspartate (NAA) peak (reflec-
www. centauro. it
The Neuroradiology Journal 21: 166-172, 2008
Figure 2 Single-voxel spectroscopy of the lesion showing elevated lactate doublet peak and a mildly decreased N-acetyl aspartate peak, compared with the contralateral side. Abbreviations: Cho, choline; Cre, creatinine; Lac, lactate; NAA, N-acetyl aspartate; ppm, parts per million.
169
Magnetic Resonance Imaging in Balo’s Concentric Sclerosis
A
A.Y.T. Al-Turkomani
B
Figure 3 A) Follow-up study. Sagittal T2-weighted image showing characteristic concentric rings with target appearance. B) Follow-up study. Sagittal T1 post-contrast image showing discontinuous concentric ring like enhancement.
tive of neuronal loss), elevated lactate doublet peak (consistent with impaired aerobic metabolism), increased choline peak, large lipid peaks and glutamine/glutamate within the lesion. Follow-up MRS showed increased myoinositol peak,decreased choline peak, dissappearance of lactate peak and low NAA peak 18,19,20. Our case showed normal choline peak, a decreased N-acetyl aspartate (NAA) peak (reflective of neuronal loss), and an elevated lactate doublet peak (consistent with impaired aerobic metabolism) within the lesion, compared with the corresponding region in the contralateral hemisphere (figure 2). There is an isolated case report on Balo’s concentric sclerosis associated with primary human herpes virus 6 infection 21. Also there is a single case report where Balo’s concentric sclerosis was associated with oligodendro-
170
glioma 22. The high incidence of this unusual demyelinating disease in the Philippines has been described in literature 23. Our case report further supports the pathognomonic MRI appearance and MRS findings of BCS, and demonstrates the multiphasic nature of the disease, well visualized in the follow-up MRI. A combination of MRI (T2, T1 post contrast, diffusion weighted images and ADC) and MRS helps to differentiate this rare demyelinating process from the more common entities such as multiple sclerosis and CNS neoplasm. The characteristic alternating zones of demyelinated and myelinated white matter are best appreciated on T2-weighted images. The ability of MR imaging to diagnose BCS earlier in its course may have a significant effect on reducing the morbidity and mortality associated with the disease.
www. centauro. it
The Neuroradiology Journal 21: 166-172, 2008
A
B
C
D
Figure 4 A-D) Follow-up study. Axial T2, FLAIR, PD and T1 weighted images showing that T2 is the best sequence for demonstration of concentric nature of the lesion.
171
Magnetic Resonance Imaging in Balo’s Concentric Sclerosis
A.Y.T. Al-Turkomani
References 1 Chen C-J, Chu N-S, Lu C-S et Al: Serial magnetic resonance imaging in patients with Balo’s concentric sclerosis: natural history of lesion development. Ann Neurol 46: 651-656, 1999. 2 Chen CJ, Ro LS, Wang LJ et Al: Balo’s concentric sclerosis: MRI. Neuroradiology 38: 322-324, 1996. 3 Ng S-H, Ko S-F, Cheung Y-C et Al: MRI features of Balo’s concentric sclerosis. Br J Radiol 72: 400-403, 1999. 4 Garbern J, Spence AM, Alvord EC Jr: Balo’s concentric demyelination diagnosed premortem. Neurology 36: 1610-1614, 1986. 5 Spiegel M, Krüger H, Hofmann E et Al: MRI study of Baló’s concentric sclerosis before and after immunosuppressive therapy. J Neurol. 236: 487-488, 1989. 6 Balo J: Encephalomyelitis periaxialis concentrica. Arch Neurol Psychiatry 19: 242-264, 1928. 7 Courville CB: Concentric sclerosis. In: Vincken PJ, Bruyn GW (eds): Handbook of Clinical Neurology, Volume 9. North Holland, Amsterdam 1970: 437-451. 8 Bolay H, Karabudak R, Tacal T et Al: Balo’s concentric sclerosis: report of two patients with magnetic resonance imaging follow-up. J Neuroimag 6: 98-103, 1996. 9 Weinshenker BG, Miller: Multiple sclerosis: one disease or many? In: Siva A, Kesselring J, Thompson AJ (eds): Frontiers in Multiple Sclerosis. 2nd edn. Martin Dunitz Ltd, London 1999: 37-46. 10 Ercan Karaarslan, Ayse Altintas, Utku Senol et Al: Baló’s Concentric Sclerosis: Clinical and Radiologic Features of Five Cases. Am J Neuroradiol 22: 13621367, 2001. 11 Yao L, Webster H, Hudson L et Al: Concentric sclerosis (Balo): morphometric and in situ hybridization study of lesions in six patients. Ann Neurol 35: 18-30, 1994. 12 Kastrup O, Stude P, Limmroth V: Balo’s concentric sclerosis. Evolution of active demyelination demonstrated by serial contrast-enhanced MRI. J Neurol. 249: 811-814, 2002. 13 Chen CJ, Chu NS, Lu CS et Al: Serial magnetic resonance imaging in patients with Balò’s concentric sclerosis: natural history of lesion development. Ann Neurol 46: 651-656, 1999. 14 Khonsari RH, Calvez V: Concentric demyelination by self-organization: a new hypothesis for Baló’s sclerosis. Nat Clin Pract Neurol 3: E1, 2007. 15 Stadelmann C, Ludwin S, Tabira T et Al: Tissue preconditioning may explain concentric lesions in Baló’s type of multiple sclerosis. Brain 128: 979-987, 2005. 16 Ball T, Roncaroli F, Quest RA et Al: Apparent diffusion coefficient changes and lesion evolution in Balos type demyelination-correlation with histopathology. Clinical Radiology 62: 498-503, 2007.
172
17 Kavanagh, Heran MKS, Fenton DM et Al: Diffusion weighted imaging findings in Balo concentric sclerosis. Br J Radiol 79: 28-31, 2006. 18 Khiat A, Lesage J, Boulanger Y: Quantitative MRS study of Baló’s concentric sclerosis lesions. Magn Reson Imaging 25: 1112-1115, 2007. 19 Kim MO, Lee SA, Choi CG et Al: Balo’s concentric sclerosis: a clinical case study of brain MRI, biopsy, and proton magnetic resonance spectroscopic findings. J Neurol Neurosurg Psychiatry 62: 655-658 1997. 20 Bruneteau G, Guillevin R, Tourbah A et Al: Contribution of proton magnetic resonance spectroscopy to the diagnosis of Balo’s concentric sclerosis. Rev Neurol 161: 455-458, 2005 21 Pohl D, Rostasy K, Krone B et Al: Baló’s concentric sclerosis associated with primary human herpes virus 6 infection. J Neurol Neurosurg Psychiatry 76: 17231725, 2005 22 Shankar SK, Rao TV, Srivastav VK et Al: Balo’s concentric sclerosis: a variant of multiple sclerosis associated with oligodendroglioma. Neurosurgery 25: 982-6, 1989. 23 Kuroiwa Y, Tateishi J, Tabira T: Concentric sclerosis-with special reference to the high incidence of this unusual demyelinating disease in the Philippines. Rinsho Shinkeigaku 24: 1217-20, 1984.
Dr A.Y.T. Al-Turkomani Department of Radiology Mubarak Al-Kabeer Hospital P.O. Box 43787, Hawally Hawally, 32052 Kuwait Tel.: 009655336856 Fax: 009655437474 E-mail: [email protected]
www. centauro. it
Magnetic Resonance Imaging in Balo’s Concentric Sclerosis. A Case Report
A.Y.T. AL-TURKOMANI, T. J.E. MUTTIKKAL, A. BEN-NAKHI Department of Radiology, Mubarak Al-Kabeer Hospital; Hawally, Kuwait
Key words: Balo’s concentric sclerosis, magnetic resonance imaging, diffusion weighted imaging, magnetic resonance spectroscopy, multiple sclerosis
SUMMARY – Concentric high signal intensity zones on T2-weighted magnetic resonance images of brain strongly suggest Balo’s concentric sclerosis (BCS), a rare but recognized variant of multiple sclerosis. Differentiating BCS from multiple sclerosis or neoplasm can be difficult clinically. The pathognomonic MRI appearance can dramatically influence the course of the disease, allowing earlier diagnosis and therapy of the disease which was once considered to have an invariably fulminant and fatal course.
Introduction
Case Report
Balo’s concentric sclerosis (BCS) is generally considered to be a rare variant of multiple sclerosis. It may present clinically similar to multiple sclerosis, or with mild cognitive impairment without frank dementia, or with altered behavior and focal neurological deficits. Historically the diagnosis was made post-mortem or histopathologically by biopsy. However recent literature suggests that BCS may show characteristic radiological features that aid in antemortem diagnosis 1. The following case further confirms this impression. The differentiation between demyelinating lesions and CNS tumors such as gliomas presenting as solitary lesions has always been difficult. The pathognomonic magnetic resonance imaging (MRI) appearance of BCS together with magnetic resonance spectroscopy (MRS) helps to reach the definitive diagnosis. The initial reports of BCS suggested that the disease is rapidly progressive and fatal 2, but there are studies showing the efficacy of corticosteroids against neurological deficits associated with BCS 3. Therefore, early MR imaging influence the course of the disease, by aiding prompt diagnosis and therapy of BCS patients.
A 24-year-old man without any significant medical history or prodromal events presented to the emergency room with acute onset of left-sided weakness and numbness. There was focal neurological deficit, with grade 0 out of 5 power in the left arm and grade 2 out of 5 power in the leg, in addition to hypoesthesia. The patient was admitted with a presumptive diagnosis of stroke. MRI of brain done three days later showed a concentric area of abnormal signal intensity in the white matter adjacent to the right lateral ventricle on T2-weighted images and fluid attenuation inversion recovery (FLAIR) images (figure 1 A,B). T1-weighted images did not show any significant mass effect (figure 1C). Faint inhomogeneous contrast enhancement of the lesion was noted with gadolinium (figure 1E). Diffusion weight images showed circular rings of hyperintensity similar to the T2-weighted images (figure 1D). Apparent diffusion coefficient (ADC) images generated off-line demonstrated a peripheral zone of restricted diffusion around a central nidus of T2 shine through and unrestricted diffusion (figure 1F). This zone of restricted diffusion extended beyond the border of the lesion appreciated in T2-weighted images.
166
A.Y.T. Al-Turkomani
CT scan of abdomen and pelvis was done as a probability of metastases was considered; the scan was normal. The following laboratory tests had normal results: Lyme serology, HIV, lupus anticoagulant, Sjogren’s antibodies, homocysteine levels, antiscleroderma 70, antiSmith, anti-Jo-1 and anticardiolipin antibodies, erythrocyte sedimentation ratio, CMV and Ebstein Barr virus antibodies and blood cultures. Lumbar puncture revealed normal cell counts, glucose and total protein levels. Myelin basic protein levels were elevated at 9 ng/ml (normal range 0-4 ng/ml), but the immunoglobulin synthesis rate was normal and oligoclonal bands were absent. The patient was started on high dose methyl prednisolone, as an inflammatory process/demyelination was suspected. There was only minimal improvement and the patient was transferred to tertiary care center 12 days after the onset of symptoms for further evaluation and management. At the time of transfer the patient had grade 0 out of 5 power in the left arm and grade 2 out of 5 power in the left leg. Repeat MRI scan of brain done approximately two weeks after the onset of initial symptoms revealed few changes in the right periventricular lesion, with concentric rings appearing more conspicuous in T2 and FLAIR imaging. Single voxel magnetic resonance spectroscopy (MRS) showed normal choline peak, decreased N-acetyl aspartate (NAA) peak (reflecting neuronal loss) and elevated lactate doublet peak (consistent with impaired aerobic metabolism) within the lesion compared to the corresponding region in the contralateral hemisphere (figure 2). The presentation and neuroimaging findings were consistent with the diagnosis of Balo’s concentric sclerosis (BCS). Steroid treatment was continued and there was an improvement in the patient’s symptoms during the next few days. About three weeks after his initial presentation, the patient was discharged for rehabilitation on a tapering oral steroid regimen. Follow-up five months after initial presentation showed a significant improvement, with grade 4 out of 5 power in the left arm and leg. However the patient was having occasional paresthesia on the right side. Repeat MRI showed significant resolution of the lesion in the right periventricular region. There was a new lesion on the left periventricular region with perilesional edema. The lesion showed a concentric appearance on T2-weighted images (figure 3A), with discontinuous concentric ring-like enhancement on post-contrast T1 images (figure
Magnetic Resonance Imaging in Balo’s Concentric Sclerosis
3B). The concentric nature of the lesion was best visualized in T2-weighted images (figures 3A, 4A) and was not obvious in FLAIR (figure 4B), proton density (figure 4C) or T1-weighted images (figure 4D). Discussion Balo’s concentric sclerosis is considered to be a rare variant of multiple sclerosis. Clinical presentation may be similar to multiple sclerosis, or with mild cognitive impairment without frank dementia, or with altered behavior and focal neurological deficits. Historically, the diagnosis was made post-mortem or histopathologically by biopsy. The first antemortem diagnosis by biopsy was reported by Garben et Al in 1986 4 and the first reported case of antemortem diagnosis of Balo’s concentric sclerosis based solely on the MRI findings was by Spiegel et Al in 1989 5. In contrast to multiple sclerosis, BCS is believed to run a fulminant and fatal course 6,7. However with MR imaging, BCS can be identified earlier when the characteristic pattern of demyelination is seen. As a result, early therapy can be instituted to provide symptomatic relief and slow down the progression of inflammatory demyelination. There are case reports of clinical improvement after the administration of corticosteroids in the literature 3,8. Our case demonstrates the unusual multiphasic nature of the illness, well demonstrated by the follow up MRI which shows resolution of the lesion on the right, and appearance of a new active lesion with pathognomonic imaging features on the left. The characteristic MR appearance when present, suggests the diagnosis of BCS as seen in our case where the T2-weighted and the FLAIR images showed separate concentric zones of demyelination (figures 1A, B, 3A, 4A). T1-weighted images following administration of gadolinium demonstrated discontinuous rings of enhancement at sites of increased bloodbrain barrier permeability and inflammation responsible for demyelination in a characteristic concentric pattern (figure 3B). The imaging findings correspond to the characteristic pathological findings of alternating rings of myelin preservation or remyelination and myelin loss, which appear as concentric pattern streaks alternating between light and shade, resembling a tree trunk cross-section or onion rings 9,10. Various theories have been proposed to explain the pathogenesis of BCS and the radio167
Magnetic Resonance Imaging in Balo’s Concentric Sclerosis
A.Y.T. Al-Turkomani
Figure 1 A) Axial T2-weighted image and B) axial FLAIR image showing a right periventricular lesion with concentric bands of variable hyperintensity. C) Axial T1-weighted image showing absence of mass effect. D) Diffusion-weighted image and F) apparent diffusion coefficient (ADC) image showing restricted diffusion in periphery with a central nidus of unrestricted diffusion and T2 shine through. E) Axial post-contrast T1-weighted image showing faint, inhomogeneous enhancement.
graphic findings. Early researchers suggested that the alternating zones of myelinated and demyelinated white matter reflected a vascular obstructive process resulting from embolization of lipid particles produced at primary multiple sclerosis lesions 7. More recent reports dismiss the notion of remyelination and suggest that the regions of myelination are more indicative of myelin breakdown at an earlier stage of development than seen in frank demyelination. These same reports highlight the limited supportive evidence for the role of toxins and infectious/inflammatory agents in the pathogenesis of BCS 11. There are studies which suggest a synchronous origin of the concentric rings, while there are studies against it 12,13. Our study showed enhancement of the concentric rings consistent with synchronous demyelination which is explained by the hypotheses of concentric de168
myelination by self-organization which states that the microglia self-organizes into concentric rings upon chemotactic stimulation 14. Tissue preconditioning has also been proposed as a mechanism to explain the concentric lesions 15. Diffusion weighted imaging findings in Balo’s concentric sclerosis have been described in two case reports 16,17, which demonstrated the peripheral zone of restricted diffusion as seen in our case. This has been attributed to rapid demyelination. Inflammation and blood brain barrier beak down, the initiating process in demyelination may account for the restricted diffusion 16. The low spatial resolution of diffusion weighted images may account for the absence of demonstrable inner zones of restricted diffusion in cases with active demyelination in inner zones. MR spectroscopic studies have shown decreased N-acetyl aspartate (NAA) peak (reflec-
www. centauro. it
The Neuroradiology Journal 21: 166-172, 2008
Figure 2 Single-voxel spectroscopy of the lesion showing elevated lactate doublet peak and a mildly decreased N-acetyl aspartate peak, compared with the contralateral side. Abbreviations: Cho, choline; Cre, creatinine; Lac, lactate; NAA, N-acetyl aspartate; ppm, parts per million.
169
Magnetic Resonance Imaging in Balo’s Concentric Sclerosis
A
A.Y.T. Al-Turkomani
B
Figure 3 A) Follow-up study. Sagittal T2-weighted image showing characteristic concentric rings with target appearance. B) Follow-up study. Sagittal T1 post-contrast image showing discontinuous concentric ring like enhancement.
tive of neuronal loss), elevated lactate doublet peak (consistent with impaired aerobic metabolism), increased choline peak, large lipid peaks and glutamine/glutamate within the lesion. Follow-up MRS showed increased myoinositol peak,decreased choline peak, dissappearance of lactate peak and low NAA peak 18,19,20. Our case showed normal choline peak, a decreased N-acetyl aspartate (NAA) peak (reflective of neuronal loss), and an elevated lactate doublet peak (consistent with impaired aerobic metabolism) within the lesion, compared with the corresponding region in the contralateral hemisphere (figure 2). There is an isolated case report on Balo’s concentric sclerosis associated with primary human herpes virus 6 infection 21. Also there is a single case report where Balo’s concentric sclerosis was associated with oligodendro-
170
glioma 22. The high incidence of this unusual demyelinating disease in the Philippines has been described in literature 23. Our case report further supports the pathognomonic MRI appearance and MRS findings of BCS, and demonstrates the multiphasic nature of the disease, well visualized in the follow-up MRI. A combination of MRI (T2, T1 post contrast, diffusion weighted images and ADC) and MRS helps to differentiate this rare demyelinating process from the more common entities such as multiple sclerosis and CNS neoplasm. The characteristic alternating zones of demyelinated and myelinated white matter are best appreciated on T2-weighted images. The ability of MR imaging to diagnose BCS earlier in its course may have a significant effect on reducing the morbidity and mortality associated with the disease.
www. centauro. it
The Neuroradiology Journal 21: 166-172, 2008
A
B
C
D
Figure 4 A-D) Follow-up study. Axial T2, FLAIR, PD and T1 weighted images showing that T2 is the best sequence for demonstration of concentric nature of the lesion.
171
Magnetic Resonance Imaging in Balo’s Concentric Sclerosis
A.Y.T. Al-Turkomani
References 1 Chen C-J, Chu N-S, Lu C-S et Al: Serial magnetic resonance imaging in patients with Balo’s concentric sclerosis: natural history of lesion development. Ann Neurol 46: 651-656, 1999. 2 Chen CJ, Ro LS, Wang LJ et Al: Balo’s concentric sclerosis: MRI. Neuroradiology 38: 322-324, 1996. 3 Ng S-H, Ko S-F, Cheung Y-C et Al: MRI features of Balo’s concentric sclerosis. Br J Radiol 72: 400-403, 1999. 4 Garbern J, Spence AM, Alvord EC Jr: Balo’s concentric demyelination diagnosed premortem. Neurology 36: 1610-1614, 1986. 5 Spiegel M, Krüger H, Hofmann E et Al: MRI study of Baló’s concentric sclerosis before and after immunosuppressive therapy. J Neurol. 236: 487-488, 1989. 6 Balo J: Encephalomyelitis periaxialis concentrica. Arch Neurol Psychiatry 19: 242-264, 1928. 7 Courville CB: Concentric sclerosis. In: Vincken PJ, Bruyn GW (eds): Handbook of Clinical Neurology, Volume 9. North Holland, Amsterdam 1970: 437-451. 8 Bolay H, Karabudak R, Tacal T et Al: Balo’s concentric sclerosis: report of two patients with magnetic resonance imaging follow-up. J Neuroimag 6: 98-103, 1996. 9 Weinshenker BG, Miller: Multiple sclerosis: one disease or many? In: Siva A, Kesselring J, Thompson AJ (eds): Frontiers in Multiple Sclerosis. 2nd edn. Martin Dunitz Ltd, London 1999: 37-46. 10 Ercan Karaarslan, Ayse Altintas, Utku Senol et Al: Baló’s Concentric Sclerosis: Clinical and Radiologic Features of Five Cases. Am J Neuroradiol 22: 13621367, 2001. 11 Yao L, Webster H, Hudson L et Al: Concentric sclerosis (Balo): morphometric and in situ hybridization study of lesions in six patients. Ann Neurol 35: 18-30, 1994. 12 Kastrup O, Stude P, Limmroth V: Balo’s concentric sclerosis. Evolution of active demyelination demonstrated by serial contrast-enhanced MRI. J Neurol. 249: 811-814, 2002. 13 Chen CJ, Chu NS, Lu CS et Al: Serial magnetic resonance imaging in patients with Balò’s concentric sclerosis: natural history of lesion development. Ann Neurol 46: 651-656, 1999. 14 Khonsari RH, Calvez V: Concentric demyelination by self-organization: a new hypothesis for Baló’s sclerosis. Nat Clin Pract Neurol 3: E1, 2007. 15 Stadelmann C, Ludwin S, Tabira T et Al: Tissue preconditioning may explain concentric lesions in Baló’s type of multiple sclerosis. Brain 128: 979-987, 2005. 16 Ball T, Roncaroli F, Quest RA et Al: Apparent diffusion coefficient changes and lesion evolution in Balos type demyelination-correlation with histopathology. Clinical Radiology 62: 498-503, 2007.
172
17 Kavanagh, Heran MKS, Fenton DM et Al: Diffusion weighted imaging findings in Balo concentric sclerosis. Br J Radiol 79: 28-31, 2006. 18 Khiat A, Lesage J, Boulanger Y: Quantitative MRS study of Baló’s concentric sclerosis lesions. Magn Reson Imaging 25: 1112-1115, 2007. 19 Kim MO, Lee SA, Choi CG et Al: Balo’s concentric sclerosis: a clinical case study of brain MRI, biopsy, and proton magnetic resonance spectroscopic findings. J Neurol Neurosurg Psychiatry 62: 655-658 1997. 20 Bruneteau G, Guillevin R, Tourbah A et Al: Contribution of proton magnetic resonance spectroscopy to the diagnosis of Balo’s concentric sclerosis. Rev Neurol 161: 455-458, 2005 21 Pohl D, Rostasy K, Krone B et Al: Baló’s concentric sclerosis associated with primary human herpes virus 6 infection. J Neurol Neurosurg Psychiatry 76: 17231725, 2005 22 Shankar SK, Rao TV, Srivastav VK et Al: Balo’s concentric sclerosis: a variant of multiple sclerosis associated with oligodendroglioma. Neurosurgery 25: 982-6, 1989. 23 Kuroiwa Y, Tateishi J, Tabira T: Concentric sclerosis-with special reference to the high incidence of this unusual demyelinating disease in the Philippines. Rinsho Shinkeigaku 24: 1217-20, 1984.
Dr A.Y.T. Al-Turkomani Department of Radiology Mubarak Al-Kabeer Hospital P.O. Box 43787, Hawally Hawally, 32052 Kuwait Tel.: 009655336856 Fax: 009655437474 E-mail: [email protected]
