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|LETTER TO EDITOR
|Year : 2020 | Volume
| Issue : 2 | Page : 500-501
MOG Antibody-Associated Disease with Recurrent Optic Neuritis and Multiple Cranial Neuropathies: A Rare Clinical Phenotype
Amirah M Razali1, Ayesha M Zain1, Norshamsiah M Din1, Hui Jan Tan2, Chen Fei Ng2
1 Department of Ophthalmology, Universiti Kebangsaan Malaysia Medical Centre, Jalan Yaacob Latif, Bandar Tun Razak, 56000 Cheras, Kuala Lumpur, Malaysia
2 Department of Medicine, Universiti Kebangsaan Malaysia Medical Centre, Jalan Yaacob Latif, Bandar Tun Razak, 56000 Cheras, Kuala Lumpur, Malaysia
|Date of Web Publication||15-May-2020|
Dr. Chen Fei Ng
Department of Medicine, Universiti Kebangsaan Malaysia Medical Centre, Jalan Yaacob Latif, Bandar Tun Razak, 56000 Cheras, Kuala Lumpur
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Razali AM, Zain AM, Din NM, Tan HJ, Ng CF. MOG Antibody-Associated Disease with Recurrent Optic Neuritis and Multiple Cranial Neuropathies: A Rare Clinical Phenotype. Neurol India 2020;68:500-1
|How to cite this URL:|
Razali AM, Zain AM, Din NM, Tan HJ, Ng CF. MOG Antibody-Associated Disease with Recurrent Optic Neuritis and Multiple Cranial Neuropathies: A Rare Clinical Phenotype. Neurol India [serial online] 2020 [cited 2020 Nov 23];68:500-1. Available from: https://www.neurologyindia.com/text.asp?2020/68/2/500/280641
Myelin oligodendrocyte glycoprotein (MOG) antibody -associated disease is an autoimmune inflammatory demyelinating disease of the central nervous system. In recent years, antibody against MOG (MOG-IgG) has been found in aquaporin-4 (AQP4) antibody-negative neuromyelitis optica spectrum disease (NMOSD), acute demyelinating encephalomyelitis (ADEM), idiopathic transverse myelitis, and chronic relapsing inflammatory optic neuritis. The disease spectrum has since expanded to represent a unique entity on the horizon. Here, we describe a rare presentation of MOG antibody-associated disease with recurrent optic neuritis and the involvement of multiple cranial neuropathies.
A 51-year-old woman presented with blurring of vision and diplopia of the right eye, associated with numbness of the right forehead. She denied pain on eye movement, limb weakness, or ataxia. There was no fever or history of trauma. Of note, she had recurrent retrobulbar optic neuritis of the left eye 12 years ago, which responded well to intravenous methylprednisolone with no residual deficit. The relapses occurred each time upon prednisolone taper. She was investigated for multiple sclerosis but defaulted to follow-up subsequently. At current presentation, the visual acuity of her right eye was reduced at 6/18 and the left eye was normal at 6/6. There was a relative afferent pupillary defect over the right eye, with 70% reduction of the red saturation and light brightness. Bilateral optic discs were pink with well-defined margins. Fundus examination, color vision test, and Humphrey visual field were normal. Hess chart showed under-action of all extra-ocular muscles of the right eye with over-action of the left eye. [Figure 1]a Optical coherence tomography (OCT) of the retinal nerve fiber layer showed thinning of the right temporal fibers.
|Figure 1: Hess chart. (a) There was under-action of all the extra-ocular muscles in the right eye with over-action in the left eye at initial presentation. (b) The ocular motility was normal bilaterally after 3 months of treatment|
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Blood investigations were normal for full blood count, renal, liver, and thyroid function tests. Anti-nuclear antibody was weakly positive at a titer of 1:80. Retroviral, syphilis, hepatitis B, and C screening were negative. Magnetic resonance imaging (MRI) of the brain was normal. Visual evoked potential showed delayed P100 on the left and absent P100 on the right in keeping with bilateral optic neuritis. Serum MOG-IgG was tested positive at the titer of more than 1:10. Serum AQP4 antibody was negative. There was no cerebrospinal fluid analysis as she declined for lumbar puncture. She was given intravenous methylprednisolone 1 gram daily for 3 days followed by a tapering course of oral prednisolone with the addition of azathioprine. At 3-months follow-up, she had complete resolution of all the symptoms. The repeated Hess chart showed a complete resolution of her right ophthalmoplegia. [Figure 1]b Neurophysiological study of blink reflex revealed normal conduction bilaterally.
MOG is a glycoprotein uniquely expressed on the myelin exclusively in the central nervous system. Several isoforms were identified, namely a and b isoforms, of which the role could be a cellular receptor, an adhesion molecule or a regulator of microtubule stability. MOG-IgG has been identified in different clinical phenotypes of demyelinating diseases including NMOSD, ADEM, brainstem encephalitis, recurrent optic neuritis, and transverse myelitis. The understanding of its pathogenic role was a breakthrough as the treatment approach varies from other demyelinating diseases.
As MOG is a protein expressed by oligodendrocytes, the disease is essentially confined in the central nervous system. Until recently, cranial nerve involvement was described in a large cohort of 273 patients with MOG antibody-associated disease. All three patients demonstrated cranial nerve root enhancement on MRI of the brain. Similarly, our patient also had unilateral involvement of the oculomotor, trochlear, abducens and trigeminal nerves. Interestingly, the MRI brain did not show any lesion in the brainstem or the nerve roots. It is postulated that such cranial neuropathies could be owing to downstream inflammatory process from the intra-axial pontine lesions. However, there could be presence of other unknown or undiscovered autoantibodies targeting the peripheral nerves during the disease process, resulting in a double-hit phenomenon. This has been observed in some autoimmune disorders such as the coexistence of Sjogren's syndrome and systemic lupus erythematosous in NMOSD.
Optic neuritis is the most common neurological symptom of MOG antibody-associated disease. OCT has frequently been used and it may show microcystic macula edema and thinning of the retinal nerve fiber layer. MOG antibody-associated optic neuritis often affects the anterior optic pathway, whereas in AQP4 antibody-associated optic neuritis, posterior optic pathway involvement, and longer lesions are usually seen. These features may be evident with gadolinium enhancement on optic nerve MRI.
To date, there is no randomized controlled trial for the treatment of MOG antibody-associated disease. In view of the highly relapsing disease course, prolonged steroid taper with low dose steroid maintenance was suggested. Other immunosuppressive agents such as azathioprine, mycophenolate mofetil, rituximab, and intravenous immunoglobulins have been used with success. The therapeutic option should be individualized considering patient's characteristics, clinical phenotype, and safety profile of the agents.
MOG antibody-associated disease has a wide clinical spectrum. Cranial nerve involvement is rarely seen, and the pathophysiology is still unclear. The observation of cranial neuropathies suggests that the disease could be broader than previously thought.
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Conflicts of interest
There are no conflicts of interest.
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