Evaluation of Retinal Nerve Fiber Layer in Patients with Idiopathic Optic Perineuritis using Optical Coherence Tomography

The crucial role of gadolinium-enhanced MRI in a case of amaurosis fugax - a case report and literature review

Optic perineuritis is the inflammation of the optic nerve sheath. This affliction can lead to visual field impairment and other signs and symptoms related to the orbital space, such as pain, disc edema, ophthalmoplegia, proptosis. However, not all patients present with such suggestive symptoms, requiring a thorough assessment. We report the case of a young male admitted to our hospital for recurrent episodes of monocular blindness. Amaurosis fugax is a well-known presentation of transient ischemic attacks (TIA) and it was ruled out. Gadolinium-enhanced MRI revealed a typical aspect of optic perineuritis. It was mandatory to consider all possible causes of secondary optic perineuritis as they all represent serious clinical conditions, even if the idiopathic form is more frequent. The clinical and paraclinical evaluation of the patient excluded an underlying disease and primary optic perineuritis was diagnosed. Corticosteroid therapy is usually curative and a course of methylprednisolone was initiated for our patient with good outcome. However, response to treatment is not diagnostic as both primary and secondary optic perineuritis are normally responsive, hence thorough differential diagnosis is necessary.

Beyond Myelin Oligodendrocyte Glycoprotein and Aquaporin-4 Antibodies: Alternative Causes of Optic Neuritis

Optic neuritis (ON) is the most common cause of vision loss in young adults. It manifests as acute or subacute vision loss, often accompanied by retrobulbar discomfort or pain during eye movements. Typical ON is associated with Multiple Sclerosis (MS) and is generally mild and steroid-responsive. Atypical forms are characterized by unusual features, such as prominent optic disc edema, poor treatment response, and bilateral involvement, and they are often associated with autoantibodies against aquaporin-4 (AQP4) or Myelin Oligodendrocyte Glycoprotein (MOG). However, in some cases, AQP4 and MOG antibodies will return as negative, plunging the clinician into a diagnostic conundrum. AQP4- and MOG-seronegative ON warrants a broad differential diagnosis, including autoantibody-associated, granulomatous, and systemic disorders. These rare forms need to be identified promptly, as their management and prognosis are greatly different. The aim of this review is to describe the possible rarer etiologies of non-MS-related and AQP4- and MOG-IgG-seronegative inflammatory ON and discuss their diagnoses and treatments.

Optic perineuritis: A Canadian case series and literature review

BACKGROUND

Optic perineuritis (OPN) is a rare orbital inflammatory disorder that primarily involves the optic nerve sheath (ONS). This study aimed to describe the clinical features of idiopathic OPN as well as OPN secondary to other infectious and inflammatory conditions in a Canadian case series as current literature on secondary OPN in Western countries is mostly limited to case reports.

METHODS

Retrospective case series of all patients seen in a tertiary neuro-ophthalmology practice with a diagnosis of OPN from 2014 to 2020.

RESULTS

A total of 21 patients (14 women, mean age 55.8) corresponding to 29 eyes with OPN were identified. Fifteen cases were associated with inflammatory or infectious conditions and only 6 were idiopathic. All idiopathic cases were unilateral. The most common secondary causes of OPN were anti-myelin oligodendrocyte glycoprotein (MOG) antibody disease (n = 4), syphilis (n = 3), sarcoidosis (n = 3), and giant cell arteritis (n = 3). At initial presentation, best-corrected visual acuity (BCVA) was 20/20 or better in 24% (n = 7) and visual field mean deviation (VF MD) was better than -5 dB in 34% of eyes (10/29). Treatment consisted of intravenous penicillin for syphilitic OPN and high-dose corticosteroids followed by oral taper with or without immunosuppressive therapy for non-syphilitic OPN. BCVA improved in 34% (10/29) and VF MD improved in 45% (13/29) eyes.

CONCLUSION

OPN primarily occurred in association with systemic inflammatory conditions, especially in bilateral cases. Syphilis must be ruled out in all patients. Anti-MOG antibody disease is an important, newly recognized secondary cause of OPN, and serologic testing should be included in the investigation of all patients with OPN.

Optic Perineuritis

Optic perineuritis (OPN) is now defined as "a form of idiopathic orbital inflammatory disease, in which the specific target tissue is the optic nerve sheath". It may be idiopathic or may occur as part of an underlying systemic inflammatory disease. It is a rare disorder and information regarding its presentation and management is only available in case reports and small case series. This review will discuss the contribution of these recent articles to what is known about idiopathic and secondary OPN. Suggestions will also be made as to how to investigate and treat a patient presenting with OPN.