Demyelinative optic neuritis (ON) is the most common type of optic nerve inflammation mostly seen in young females characterized by unilateral, subacute, painful visual loss. It can be the first presentation of MS in around 20% of the patients and can occur in 50% during the course of the disease. Pain exacerbated by eye movements is very typical. The decrease in visual acuity ranges in severity and is associated with depressed color vision and contrast sensitivity. Visual field defects, mainly involve the central field. Fundoscopic examination reveals a normal optic disc in around 65% of the cases. Optic disc edema can be found in around 35%. The visual outcome is generally favorable. Recovery begins within the first weeks and 92% of the patients recover to 20/40 or better.
Absence of pain, severe visual loss at onset, persisting or progressive visual loss, recurrence especially after cessation of steroid treatment, simultaneous bilateral involvement, optic disc edema with peripapillary hemorrhages and exudates are accepted as atypical findings for demyelinative ON and necessitates search for other causes such as infections (syphilis, lyme, bartonella), sarcoidosis or vasculitis.
With the identification of AQP4-IgG and the updated 2015 clinical criteria for neuromyelitis optica spectrum disorders (NMOSD), patients with a single ON attack with atypical features for demylinative ON could be diagnosed with NMOSD. In around 28% of patients with recurrent ON and negative for AQP4-IgG has been shown to harbor antimyelin oligodendrocyte glycoprotein antibodies (MOG-Abs). As treatment strategies differ significantly in these disorders appropriate laboratory testing in patients with atypical features is mandatory.
Key points:
- Optical neuritis
- atypical findings
- neuromyelitis optica spectrum disorders
- myelin oligodendrocyte glycoprotein antibodies
References: