What is Neuromyelitis Optica?
Neuromyelitis optica (NMO) or Devic´s disease is a demyelinating syndrome of the central nervous system characterized by preferential involvement of the optic nerve and spinal cord.
NMO is a rare disease with an estimated prevalence of 1-2 cases/100.000 population, although probably is overrepresented in the Caucasian population. The disease is nine times more common in women than in men, the average age of onset is 39 years old, although there are also cases in children and elderly people.
How is the course of the disease?
The 80-90% of the patients have a course characterized mainly by relapses, normally with an incomplete recovery, and consequently an increasing discapacity related with the frequency and severity of the relapses. More than 50% of the patients become blind in one or both eyes or they need help to walk during the first five years of the disease, and mortality is described as much as 20% of the patients generally associated with cervical spinal relapses.
What is happening?
NMO was initially considered as a variant of Multiple Sclerosis but associated with a different prognosis and therapeutic approach. The suggested role of humoral immunity in the pathogenesis of the disease based in histological studies was confirmed when the presence of antibodies (IgG-NMO) highly sensitive (73%) and specific (91%) for the diagnosis was detected. Later on, they discovered that there were anti-aquaporine-4 antibodies, against a water channel selectively expressed in the astrocytes foot and in direct contact with the blood brain barrier.
The identification of these antibodies allowed a better diagnosis of the disease and therapeutic decision, and extends the clinical spectrum associated with its presence in patients with monosymptomatic forms as recurrent optic neuritis or longitudinally extensive transverse myelitis, and more atypical forms with involvement beyond the optic nerve and the spinal cord. Nevertheless, there are a percentage of patients, between 20%-30% that despite the presence of characteristic clinical features, are seronegatives and the presence of IgG-NMO antibodies is not detectable.
Patients who otherwise do not look different immunologically or genetically speaking. Nevertheless, is discussed whether Caucasian patients are different from the no-Caucasian ones, and if there are differences in the clinical and evolutionary aspects between seronegative patients and the ones presenting IgG-NMO antibodies.
How is the disease treated?
This centre was the first one in Spain to incorporate the technique to detect IgG-NMO antibodies. The study of this disease, from the more basic aspects to epidemiology, had been and is a prioritary area of research of our group with the idea to transferring the results to the clinical practice in order to have a better diagnosis and a more adequate therapeutic strategy.