Neuromyelitis Optica Spectrum Disorder is an inflammatory disease that causes demyelination of the central nervous system, primarily affecting the optic nerve (optic neuritis) and the spinal cord.
NMO is characterized by segmented demyelination and inflammation of the spinal cord and the optic nerves inducing axonal loss and perivascular lymphocytic infiltration.
NMOSD can occur in any ethnicity, either gender, and any age, the disease has a predilection for females and may be more common in patients of Asian or African descent.
AQP4-IgG+ NMOSD is 9 times more prevalent in women vs men.Median onset: ∼40 years.
Pathophysiology: NMOSD is primarily an astrocytopathy. It involves demyelination and inflammation of multiple spinal cord segments and the optic nerves. NMOSD produces significant axonal loss associated with perivascular lymphocytic infiltration and vascular proliferation.
NMO is characterized by a disease specific IgG antibody against the astrocytic aquaporin 4 (AQP4) water channel (also known as the aquaporin-4 autoantibody (anti-AQP4 or AQP4-IgG).The AQP4 water channel membrane protein is concentrated in the optic nerve, area postrema, and spinal cord.AQP4 rich areas of the CNS account for the clinical findings of NMOSD.
AQP4 autoantibodies mediate astrocyte destruction via complement-dependent and -independent mechanisms, leading to widespread damage in surrounding tissues.Death of astrocytes induces secondary death of oligodendrocytes, resulting in demyelination and ultimately neuronal cell death.
Clinical features:
Transverse myelitis-Lhermitte’s phenomenon;Intractable pain;Bladder and bowel dysfunction;Weakness and paralysis;Loss of sensation;Paroxysmal tonic spasms of the trunk and limbs
Optic neuritis- Ocular pain, Unilateral and bilateral loss of visual acuity, leading to blindness
Area postrema syndrome- Nausea,Vomiting, Intractable hiccups
Diagnosis:
Diagnostic criteria for NMOSD with serum positive AQP4-IgG:
At least 1 core clinical characteristic
Positive test for AQP4-IgG using best available detection method
Exclusion of alternative diagnoses: Multiple sclerosis;Acute disseminated encephalomyelitis;MOG associated optic neuritis;Systemic lupus erythematosus;Neuro - Behçet disease
Management: Acute attacks of NMO are treated with IV corticosteroids, with plasma exchange for fulminant attacks. Long-term immunomodulatory therapies to reduce the risk of subsequent relapses include Rituximab (monoclonal antibody against CD20 that deplets B cells), Eculizumab (monoclonal antibody against C5 that inhibits complement-induced MAC), Inebilizumab (MA against CD19 that deplets B cells, Tocilizumab (MA against Il-6).
NMOSD vs Multiple sclerosis: Necrosis in NMOSD usually involves both gray and white matter.
MRI findings: Periventricular lesions: MS- adjacent to lateral ventricles; NMO-adjacent to third and fourth ventricles. Spinal cord lesions: MS-small, radially oriented. NMO- longitudinally extensive.
The optic neuritis in NMOSD superficially may resemble MS, NMOSD related optic neuritis tends to be more severe, more extensive, more likely to be bilateral, recurrent and be less likely to recover than the optic neuritis seen in MS.
Oligoclonal bands: MS- common; NMO- uncommon.
Disease course: MS- relapses with near complete recovery, following a progressive course; NMO-attacks with incomplete recovery, even after the first attack
Негізгі бет Ani Papiashuvili Neuromyelitis Optica
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