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Table of Contents    
LETTER TO EDITOR
Year : 2022  |  Volume : 70  |  Issue : 4  |  Page : 1682-1683

‘H’ Sign in a Case of MOG Myelitis


Department of Neurology, Sahyadri Superspecialty Hospital, Pune, Maharashtra, India

Date of Submission05-Nov-2019
Date of Decision30-Aug-2022
Date of Acceptance11-Jul-2020
Date of Web Publication30-Aug-2022

Correspondence Address:
Bhushan Mishal
Sahyadri Superspeciality Hopsital, Karve Road, Erandwane, Pune, Maharashtra
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0028-3886.355180

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How to cite this article:
Mishal B, Divate P. ‘H’ Sign in a Case of MOG Myelitis. Neurol India 2022;70:1682-3

How to cite this URL:
Mishal B, Divate P. ‘H’ Sign in a Case of MOG Myelitis. Neurol India [serial online] 2022 [cited 2022 Oct 2];70:1682-3. Available from: https://www.neurologyindia.com/text.asp?2022/70/4/1682/355180




Sir,

Myelin oligodendrocyte glycoprotein (MOG) associated myelitis is a relatively newer addition to the group of demyelinating conditions affecting the spinal cord, brain and optic nerves. It is an Aquaporin-4 negative myelitis and is an important entity to recognize in view of its favorable prognosis as compared to Aquaporin- 4 positive myelitis. MOG in contrast to Neuro Myelitis Optica (NMO) is an oligodendrocytopathy: MOG glycoprotein is expressed on oligodendrocytes and is found exclusively in the Central Nervous System.[1] This glycoprotein is located on the surface of myelin sheath and becomes vulnerable to the attack of antibodies. MOG antibody disease now has been recognized as a distinct Neuro- inflammatory disease differing from NMO and MS. It is a disorder involving the cerebral hemispheres causing Acute Disseminated Encephalo-Myelitis (ADEM) [Figure 1], [Figure 2], [Figure 3]; mainly involving the brain stem, optic nerves, and spinal cord and recently, focal cortical disease.[2] The spectrum of this disease is expanding.[3]
Figure 1: MRI brain (5/6/18) FLAIR and contrast showing edema involving left parietal-temporal white matter

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Figure 2: Follow-up MRI (19/10/18) showing a significant reduction in edema and mass effect with no contrast enhancement post steroid treatment

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Figure 3: MRI brain (8/1/19) FLAIR sequence showing nonenhancing area of ill-defined signal abnormality and area of gliosis in left peritrigonal white matter without contrast enhancement

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We would like to draw the attention of the readers to the description of the H sign which has been described in MOG myelitis. It is seen on axial T2 MRI images and is seen as a hyperintensity of the gray matter of the spinal cord resembling the alphabet 'H' [Figure 4] and [Figure 5]. In a recent publication from Mayo Clinic, the 'H' sign was observed in 15/51 (29%) patients of MOG-associated myelitis, 3/38 (8%) of Aquaporin-4 IgG myelitis and none of the 29 M.S. myelitis.[4] Thus, the H sign observed in the axial MRI, though not specific of MOG myelitis is suggestive of it; this sign is caused probably by inflammation of the central gray matter.
Figure 4: MRI spine (8/1/19) showing long segment hyperintensity on T2 sequence from D6 to D12, with heterogeneous contrast enhancement

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Figure 5: Axial MRI T2 sequence of spinal cord showing “H” sign

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We present MRI images of one of our cases of MOG myelitis which illustrates the H sign.The key message we wish to convey is that, in a case of a longitudinally extensive myelitis, the presence of the H sign on axial T2 MRI images of the spinal cord should arouse suspicion of MOG associated myelitis.

Financial support and sponsorship

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Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Wynford-Thomas R, Jacob A, Tomassini V. Neurological update: MOG antibody disease. J Neurol 2019;266:1280-6.  Back to cited text no. 1
    
2.
Juryńczyk M, Jacob A, Fujihara K, Palace J. Myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease: Practical considerations. Pract Neurol 2019;19:187-95.  Back to cited text no. 2
    
3.
Reindl M, Waters P. Myelin oligodendrocyte glycoprotein antibodies in neurological disease. Nat Rev Neurol 2019;15:89-102.  Back to cited text no. 3
    
4.
Dubey D, Pittock SJ, Krecke KN, Morris PP, Sechi E, Zalewski NL, et al. Clinical, radiologic, and prognostic features of myelitis associated with myelin oligodendrocyte glycoprotein autoantibody. JAMA Neurol 2019;76:301-9.  Back to cited text no. 4
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]



 

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