Neuromyelitis Optica (NMO) is a rare but severe demyelinating disease, characterized by severe optic neuritis and spinal myelitis.
Disease characteristics of NMO
Clinical findings
Devic’s NMO generally presents as an acute disease, with an onset in 30-50% of the cases preceded by a virus-like syndrome, with headache, subfebrility, fatigue, myalgia or res- piratory and gastrointestinal symptoms. It can also be associated with autoimmune diseases, such as systemic lupus erythematosus, Sjögren, myasthenia gravis or Hashimoto thyroiditis. Some authors suggest that these infec- tions or autoimmune diseases are the trigger for the onset of NMO, but a real pathophysiological associa- tion or etiology of NMO remains unknown.
NMO starts with two index events, optic neuritis and myelitis, which can occur simultaneously or separated by an interval of several days up to 5 years. Optic neuritis presents with a sudden and severe unilateral visual loss, which can recover but often results in complete loss of vision. In a minority of the patients the contralateral eye will be affected within a few days.
The myelitis manifests with paresthesias and progressive weakening of the lower extremities. A simultaneous presence of motor, sensory and sphincter symptoms is more frequently observed in NMO than in patients with multiple sclerosis. In half of the cases, myelitis will lead to severe paraparesis or quadriparesis. A cervical spine lesion can eventually cause death by respiratory paralysis.
Either the patient will have no other attacks (monophasic form), or they will have repeated attacks (relapsing), more common.
DIAGNOSIS
Cerebrospinal fluid and immunology
Cerebrospinal fluid (CSF) analysis typically demonstrates pleocytosis (50 cells/mm3) and an absence of oligoclonal bands. Pleocytosis is more frequently seen in the active phase of the disease. Although oligoclonal bands are typically absent in NMO, they may, similar to MS, appear during the course of the disease, but in contrary to MS, they may also disappear.
Therefore, repeated CSF examinations should be done in suspected NMO, preferably in different disease phases.
Recently, a serum antibody marker named “NMO-IgG” was discovered and seems to be valuable in distinguishing NMO from MS. The reported sensitivity and specificity of NMO-IgG for NMO are 73% and 91%.
Imaging findings of NMO
MR imaging is an important diagnostic tool in case of a suspected demyelinating disease. In NMO, conventional MRI of the brain and spine can help in differentiating patients with NMO from those with MS.
Brain MRI may demonstrate inflammation of the optic pathways during acute optic neuritis.
The absence of white matter lesions on a brain MRI has traditionally been considered as a major supportive diagnostic criteria for the diagnosis of NMO.
Today, most authors consider the presence of non-specific white matter abnormalities at the onset of the disease not a contradiction for the diagnosis of NMO as long as the characteristics and distribution of these lesions do not fulfill radiological criteria for MS.
Spinal cord MRI is the most discriminative imaging test for NMO. Acute spinal myelitis is typically associated with lesions extending over 3 or more vertebral segments, which is best appreciated on sagittal T2-weighted images. Axial SE T2 weighted images will demonstrate a central location of the lesions.
Occasionally the whole cross sectional area of the medulla is involved. In NMO the lesions may show T1 hypointensity, which may represent necrotic inflammation. Contrast enhancement after administration of gadolinium can be present. During an acute episode of NMO the cord may be swollen,while in chronic phases an atrophic appearance can be expected.
DIFFERENCES BETWEEN MS AND NMO:
_______________________________________________
BRAIN MRI:
_______________________________________________
WHITE MATTER LESIONS:
NMO= Not present or nonspecific lesions
MS= Multiple bilateral asymmetric lesions perpendicular
to ventricles, subcortical.
MRI CRITERIA FOR MS:
NMO= Not fulfilled: MANDATORY
MS= Typically fulfilled.
________________________________________________
SPINE MRI
________________________________________________
NMO=Longitudinal extension >/= 3 vertebral segments
MS= Longitudinal extension </= 2 vertebral segments
NMO=T1 hypointensity YES
MS=T1 hypointesity NO
NMO=Whole cross sectional area involvement? YES
MS= Whole cross sectional area involvement? NO
NMO=Preferential location: Central
MS= Preferential location: Posteriolateral
NMO=Cord atrophy or swelling: YES
MS= Cord atrophy or swelling: Rarely
________________________________________________
Treatment:
MS: DMDs
NMO: DMDs do not work for NMO. Treatment consists of methylprednisone for attacks, plasma exchange has shown some promise in some patients. Some centers use
azathioprine in combination with oral predinsone, some use mitoxantrone, intravenous immunoglobulin, and rituximab to reduce relapses in those resistant to other therapies.
Source: https://www.google.com/url?sa=t&rct=...qsjy0ZodEZ1Yxg
Disease characteristics of NMO
Clinical findings
Devic’s NMO generally presents as an acute disease, with an onset in 30-50% of the cases preceded by a virus-like syndrome, with headache, subfebrility, fatigue, myalgia or res- piratory and gastrointestinal symptoms. It can also be associated with autoimmune diseases, such as systemic lupus erythematosus, Sjögren, myasthenia gravis or Hashimoto thyroiditis. Some authors suggest that these infec- tions or autoimmune diseases are the trigger for the onset of NMO, but a real pathophysiological associa- tion or etiology of NMO remains unknown.
NMO starts with two index events, optic neuritis and myelitis, which can occur simultaneously or separated by an interval of several days up to 5 years. Optic neuritis presents with a sudden and severe unilateral visual loss, which can recover but often results in complete loss of vision. In a minority of the patients the contralateral eye will be affected within a few days.
The myelitis manifests with paresthesias and progressive weakening of the lower extremities. A simultaneous presence of motor, sensory and sphincter symptoms is more frequently observed in NMO than in patients with multiple sclerosis. In half of the cases, myelitis will lead to severe paraparesis or quadriparesis. A cervical spine lesion can eventually cause death by respiratory paralysis.
Either the patient will have no other attacks (monophasic form), or they will have repeated attacks (relapsing), more common.
DIAGNOSIS
Cerebrospinal fluid and immunology
Cerebrospinal fluid (CSF) analysis typically demonstrates pleocytosis (50 cells/mm3) and an absence of oligoclonal bands. Pleocytosis is more frequently seen in the active phase of the disease. Although oligoclonal bands are typically absent in NMO, they may, similar to MS, appear during the course of the disease, but in contrary to MS, they may also disappear.
Therefore, repeated CSF examinations should be done in suspected NMO, preferably in different disease phases.
Recently, a serum antibody marker named “NMO-IgG” was discovered and seems to be valuable in distinguishing NMO from MS. The reported sensitivity and specificity of NMO-IgG for NMO are 73% and 91%.
Imaging findings of NMO
MR imaging is an important diagnostic tool in case of a suspected demyelinating disease. In NMO, conventional MRI of the brain and spine can help in differentiating patients with NMO from those with MS.
Brain MRI may demonstrate inflammation of the optic pathways during acute optic neuritis.
The absence of white matter lesions on a brain MRI has traditionally been considered as a major supportive diagnostic criteria for the diagnosis of NMO.
Today, most authors consider the presence of non-specific white matter abnormalities at the onset of the disease not a contradiction for the diagnosis of NMO as long as the characteristics and distribution of these lesions do not fulfill radiological criteria for MS.
Spinal cord MRI is the most discriminative imaging test for NMO. Acute spinal myelitis is typically associated with lesions extending over 3 or more vertebral segments, which is best appreciated on sagittal T2-weighted images. Axial SE T2 weighted images will demonstrate a central location of the lesions.
Occasionally the whole cross sectional area of the medulla is involved. In NMO the lesions may show T1 hypointensity, which may represent necrotic inflammation. Contrast enhancement after administration of gadolinium can be present. During an acute episode of NMO the cord may be swollen,while in chronic phases an atrophic appearance can be expected.
DIFFERENCES BETWEEN MS AND NMO:
_______________________________________________
BRAIN MRI:
_______________________________________________
WHITE MATTER LESIONS:
NMO= Not present or nonspecific lesions
MS= Multiple bilateral asymmetric lesions perpendicular
to ventricles, subcortical.
MRI CRITERIA FOR MS:
NMO= Not fulfilled: MANDATORY
MS= Typically fulfilled.
________________________________________________
SPINE MRI
________________________________________________
NMO=Longitudinal extension >/= 3 vertebral segments
MS= Longitudinal extension </= 2 vertebral segments
NMO=T1 hypointensity YES
MS=T1 hypointesity NO
NMO=Whole cross sectional area involvement? YES
MS= Whole cross sectional area involvement? NO
NMO=Preferential location: Central
MS= Preferential location: Posteriolateral
NMO=Cord atrophy or swelling: YES
MS= Cord atrophy or swelling: Rarely
________________________________________________
Treatment:
MS: DMDs
NMO: DMDs do not work for NMO. Treatment consists of methylprednisone for attacks, plasma exchange has shown some promise in some patients. Some centers use
azathioprine in combination with oral predinsone, some use mitoxantrone, intravenous immunoglobulin, and rituximab to reduce relapses in those resistant to other therapies.
Source: https://www.google.com/url?sa=t&rct=...qsjy0ZodEZ1Yxg
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