Dr. Blanca Hernández, Clinical neurologist of demyelinating diseases of HGPS.
Optic neuromyelitis (NMO) is a disorder of the central nervous system that primarily affects the nerves of the eye (optic neuritis) and the spinal cord (myelitis). It is also known as "spectrum disorder of optic neuromyelitis" or "Devic's disease."
This disease occurs when the body's immune system reacts against its own cells of the central nervous system, mainly in the optic nerves and spinal cord, sometimes also in the brain. For many years this clinical entity has been confused with multiple sclerosis, but in 2004, the Association of Optical Neuromyelitis described an antibody against the aquaporin water channel 4 (AQP4-IgG), establishing the disease as a different pathology of multiple sclerosis. .
Cause and consequences.
The cause of optic neuromyelitis is generally unknown, although it may occasionally appear after an infection or may be associated with another autoimmune condition.
Often, optic neuromyelitis is incorrectly diagnosed as multiple sclerosis or is perceived as a type of multiple sclerosis, although this is a distinct disorder.
NMO can cause blindness in one or both eyes, weakness or paralysis in the legs or arms, painful spasms, loss of sensation, uncontrollable hiccups and vomiting, abnormal bladder or bowel function due to damage to the spinal cord.
Children may have disorientation, seizures or coma if they suffer from NMO. Exacerbations of this disease may be reversible, although its severity may be sufficient to cause permanent vision loss and walking problems.
Optic neuromyelitis frequently coexists with other autoimmune diseases: myasthenia gravis, Sjogren's syndrome, or systemic lupus erythematosus. It has a prevalence of 0.3 to 4.4 per 100,000 individuals and an incidence of less than 1 per 100,000 individuals in Western countries. It is less frequent in Caucasians than in Asians and Africans and its average age of presentation is 39, but it can also occur in children and the elderly.
Two clinical courses of the disease have been described. Single-phase course (younger patients, very rare 5-10 % of cases of NMO), in which the occurrence of optic neuritis and longitudinally extensive myelitis (MTLE), occurs with days of difference and without subsequent exacerbations.
The recurrent course is characterized by multiple repetitive episodes of optic neuritis and / or transverse myelitis (MTEL) that occur with an interval of months to several years. The male / female ratio varies according to the type of clinical course, being 1: 1 in the single phase and 1: 9 in the recurrent. The 5-year survival rate is 90 % for the single-phase course and 68 % for the recurrent, and a common cause of death is respiratory failure secondary to cervical spinal injury.
There are clinical factors that predict a worse prognosis in NMO, such as higher age of onset, high recurrence rate in the first year, poor recovery and more intensity after the first attack.
Clinical manifestations of patients
The clinical presentation of patients with disorders of the spectrum of optic neuromyelitis (NMOSD) is very variable, since the symptomatology can originate from the involvement of different areas of the central nervous system (optic nerve, spinal cord, last area, brainstem, diencephalon and brain).
Optic neuritis and longitudinally extensive transverse myelitis (MTLE) are the most frequent presenting symptoms. Bilateral optic neuritis is usually severe and causes blindness in 20-22 % of patients.
Inflammation of the marrow or transverse myelitis that can cause paralysis of the legs (paraplegia) or of the arms and / or both arms and legs (quadriplegia), clinical syndrome of the last area, consisting of vomiting and / or intractable singular (hypo) .
Other symptoms and / or clinical manifestations possible to observe in NMOSD derive from the involvement of the brainstem: vertigo, sensorineural hearing loss, facial paralysis, trigeminal neuralgia, diplopia, ptosis and nystagmus.
Symptomatic forms of narcolepsy or states of impaired consciousness, encephalopathy associated with diffuse white matter lesions in the central nervous system, posterior reversible encephalopathy syndrome (PRES) hypothermia, hypothyroidism and hyperprolactinemia have also been described.
The extension of a cervical myelitis can compromise the brainstem, causing, in severe cases, an acute neurogenic respiratory failure and, consequently, the death of the patient.