Pain in optic neuritis – the importance of careful history taking

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How is optic neuritis diagnosed? - Quora
Optic neuritis (source: Quora)

I was recently the on-call Neurologist for The Royal London Hospital, which over the weekend can have an immense catchment area extending as far as Southend Hospital. It was during said on call that I was contacted by the on-call registrar. The story was of a pregnant lady experiencing unilateral eye pain and profound visual loss. Their working diagnosis was retrobulbar neuritis (inflammation of optic nerve behind the globe); as the optic disc appearances were normal. She also complained of swelling of the affected eye and sub-conjunctival haemorrhage.

The treatment of course is steroids to dampen down the inflammation, but in someone who is pregnant you will need to evaluate the risk to the baby of this treatment, as well as the risk associated with performing a contrast enhanced MRI.

So in many cases you fall back on your history and examination to be doubly sure of your diagnosis. Understanding how different eye conditions involving optic nerve inflammation present will stand you in good stead. This is particularly important, as was in this case when the presentation was one of functional visual loss (non-organic disorder). Very few people in the community know that pain on eye movement is more characteristic of optic nerve inflammation.

This review in Frontiers, therefore was very timely. I’ve listed some of the key take home messages from this article.

  • The optic nerve itself doesn’t convey pain, the origin of the pain is the meninges covering the optic nerve.
  • At the apex of the eye cavity the optic nerve is proximal to the superior and medial rectus (eye muscles). Consequently, upon eye movement the contraction of these muscles irritate the inflamed optic nerve sheath causing pain. Mild periocular pain (around the eye) and headache may also be experienced.
  • Lack of pain following eye movement is always related to the lesion being located in the intracranial part of the optic nerve.
  • MS- optic neuritis (ON): classical pain with eye movement, unilaterality, and reversible visual impairment.
  • NMSOD (Neuromyelitis Optica)-ON: Pain followed by severe and irreversible visual loss as well as bilaterality.
  • MOGAD (MOG antibody)-ON: Bilateral severe orbital pain and headache with mild vision loss.
  • Pain resolves over a short period (normally less than 1 week) or with steroid treatment.
Figure: Different disorders that develop optic neuritis

Abstract

Front Pain Res (Lausanne). 2022 Apr 14;3:865032. doi: 10.3389/fpain.2022.865032. eCollection 2022.

Pain Symptoms in Optic Neuritis

Xiayin Yang Xuefen Li Mengying Lai Jincui WangShaoying Tan Henry Ho-Lung Chan 

Signs and symptoms of optic neuritis (ON), an autoimmune disorder of the central nervous system (CNS), differ between patients. Pain, which is commonly reported by ON patients, may be the major reason for some patients to visit the clinic. This article reviews the presence of pain related to ON with respect to underlying disorders, including multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMOSD), and myelin oligodendrocyte glycoprotein associated disease (MOGAD). The aim of this review is to provide an overview of pain symptoms in accordance with the context of various pathophysiological explanations, assist in differential diagnosis of ON patients, especially at the onset of disease, and make recommendations to aid physicians make decisions for follow up diagnostic examinations.

About the author

Neuro Doc Gnanapavan

12 comments

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  • Is it weird that when I had optic neuritis I had no pain?

    Last week I passed out and fell on my head (my ECG was weird so I’m booked in for a Holter monitor and I will make sure my MS team are aware). The written advice they gave me was to go to the ED if there were changes in my eyesight. My eyesight has gone a bit blurry in my right eye where I had the ON, it’s not getting any worse though and it’s been like that before (comes and goes and I put it down to MS), I think I’d still do very well on the eye chart so I haven’t been back to the hospital! But when I was in hospital last week there was a brief sharp pain in my left eye, the doctor wasn’t in the room and it stopped before she got back – I did find that interesting as I had really never had eye pain before.

    Recovering from something like that, with MS, is strange. I really had my fatigue under control by maintaining quite a high level of physical activity, and in fact over Easter I completed the West Highland Way in four days. But any sudden stop or reduction in activity is an invitation for fatigue to return. So I’m not sure how much of how I’m feeling now is due to the MS and how much is due to the head injury – and how will I really be able to tell when I have recovered from the head injury?

    • Pain is present in 90% according to this article in active ON. The advice for blurred vision with falls is based on concussion advice given for head injuries. When it’s mild head trauma it normally settles. Often an eye exam will help with ?ON.

  • Thanks for this. May I remind you of the observation that clinically, when simultaneous, bilateral ON occurs, this is almost always NOT MS. MS optic neuritis is most characteristically unilateral. Not only are MS attacks of ON characteristically unilateral, recurrent attacks (as you once observed jn this blog), are significantly ipsilateral. These observations on the ‘anatomy’ of MS are particularly revealing as they are in marked contrast with other conditions where there is evidence of a systemic attack across the BBB, eg ADEM, neuromyelitis optics, chronic relapsing inflammatory optic neuropathy (CRION), and the many others you refer to.
    The clear implication is that MS is not primarily an attack across the BBB, but in some way ‘internal’, with an anatomical explanation.
    You may find the proposed explanation in ‘Bacterial transportable toxins of the nasopharyngeal microbiota in Multiple Sclerosis’ Rev Neurologique 175(20190 644-649.

    • Mr Gay,

      I have read this hypothethis before – does it change the treatment target? i.e. control bacteria in the nose, control MS. Or is it a case of once the horse has bolted?

      Thanks

      • The answer to your relevant questions depends on determining the cause and the mechanism of damage in the CNS. The ‘hypothesis’ (nose to brain) is based on the epidemiological association between inflammations of the paranasal mucosa, and the histopathological observation of the presence of nasopharyngeal bacterial products in the primary MS lesions. The idea that certain bacterial products can penetrate from nose to brain is entirely reasonable, apart from the increasing interest in the influence of the microbiome on the immune system, I would have thought that the nose to CNS route has been rather obviously illustrated by Covid 19 ! (and many other microbes of course).
        This requires work to be done, rather than more speculation.

        • Thank you Frederick. This theory caught my eye as i have previously had boughts of sores / spots inside my nose which have preceded relapses. I also had my uvlea removed (incorrectly i believe) a couple of years prior to my first incident. Patients with MS spend a lot of time trying to think about the initial trigger, the cause for them – this is the one that makes most sense for me

  • I’ve had ON many times, usually painlessly. I have only had mild pain involved on two occasions, and it was so mild that if I didn’t know what I was looking for, I would have ignored it. It also caused more than one neuro to brush me off even as my OCTs got spookier and I had other signs of active ON. I now see a fabulous neuro-ophth who gets it.

    This is a really interesting post, and I thank you for it.

  • The eye I had pain in for 4hrs is the one that has only color issues now, but the other one has been painless with several episodes spanning 15yrs from vision loss with spontaneous full recovery to developing permanent central vision loss. My question is regarding the absence of optic nerve lesions. Is that possible? I’ve had several scans, including the orbits, and narrowing of the nerve is the only comment. Thank you!

    • When done in the acute scenario the MRI orbits with contrast is a very sensitive study (I noted this in the phenytoin optic neuritis study – PI Raj Kapoor). There is silent ON and the fellow unaffected eye can similarly show appearances of hidden involvement. The thinning of the optic tract in itself occurs post optic neuritis in the context of MS when there is no other compressive lesion nearby.

  • Thank you for this article. One of the first signs of my MS was facial paralysis and ON. I had one round of steroids. However the pain has never subsided. It has continued daily for over a year. Is this unusual?

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