The article¹ commented on herein offers a brief historical review of neuromyelitis optica (NMO) and shows the changes that have occurred in the diagnostic criteria in recent decades, including the discovery of the anti-aquaporin 4 antibody (AQP-4) and the introduction of the concept of an NMO spectrum disorders (NMOSD). It is fundamental for ophthalmologists to learn regarding these changes, considering the fact that one aspect of the NMOSD is atypical optic neuritis, for which patients typically seek an ophthalmologist first.

The classic concept of NMO (or Devic's disease) was that it was a variant of multiple sclerosis (MS) characterized by myelitis and concomitant bilateral optic neuritis or, in a short period, associated with serious vision loss and a lower chance of visual recovery than in the case of typical optic neuritis associated with MS.² However, other patients with NMO have differently presented with unilateral optic neuritis and without serious vision loss or recurring crises.² Therefore, a definitive diagnosis of NMO was difficult, considering the clinical variability and lack of specific laboratory examinations.

The 2004 discovery of AQP-4 in patients with NMO³ filled this laboratory gap in the diagnostic criteria and provided valuable information regarding the pathophysiology of the disease. The concept of a clinical spectrum of NMO has been introduced, with the existence of limited forms of the disease, one of which is isolated optic neuritis without myelitis.⁴

In the article commented on herein¹, the authors propose the term expanded spectrum of neuromyelitis optica to include other limited forms of NMO even in patients who test negative for AQP-4. These forms include optic neuritis (without myelitis) presenting with atypical characteristics such as vision loss worse than 20/400 and a lack of visual recovery, in addition to concomitant bilateral impairment or recurrent events. The authors suggests that the presence of typical NMO lesions in a brain MRI may be used as an alternative criterion to the antibody in patients who test negative for AQP-4. However, critical judgment is necessary before MS and other related conditions being excluded in patients with suspected NMO.

The final message of the authors is to call attention about the importance of recognizing the limited forms of NMO (such as atypical optical neuritis) in order to promote early diagnosis and, therefore, an appropriate immunosuppressive treatment to reduce the risk of recurrences and permanent visual or neurological damage.

REFERENCES

1 Lana-Peixoto MA, Callegaro D. The expanded spectrum of neuromyelitis optica: evidences for a new definition. Arq Neuropsiquiatr 2012;70(10):807-13. http://dx.doi.org/10.1590/S0004-282X2012001000010

2 Wingerchuk DM, Hogancamp WF, O'Brien PC, Weinshenker BG. The clinical course of neuromyelitis optica (Devic's syndrome). Neurology 1999;53(5):1107-14. http://dx.doi.org/10.1212/WNL.53.5.1107

3 Lennon VA, Wingerchuk DM, Kryzer TJ, Pittock SJ, Lucchinetti OF, Fujihara K, Nakashima I, Weinshenker BG. A serum autoantibody marker of neuromyelitis optica: distinction from multiple sclerosis. Lancet 2004;364(9451):2106-12. http://dx.doi.org/10.1016/S0140-6736(04)17551-X

4 Wingerchuk DM, Lennon VA, Lucchinetti OF, Pittock SJ, Weinshenker BG. The spectrum of neuromyelitis optica. Lancet Neurol 2007;6(9):805-15. http://dx.doi.org/10.1016/S1474-4422(07)70216-8

Frederico Castelo Moura Correio
http://orcid.org/0000-00Q2-7949-6832
http://lattes.cnpq.br/7327083350865058

Received on: July 30, 2015.
Accepted on: August 5, 2015.