Neuromyelitis optica

From EyeWiki
Original article contributed by: Grecia Rico
All contributors: Ayman Okla Suleiman, MD
Assigned editor: Andrew Go Lee, MD
Review: Assigned status Up to Date by Ayman Okla Suleiman, MD on September 14, 2015.



Neuromyelitis optica
Classification and external resources
ICD-10 [1]36.0


Neuromyelitis optica (also referred as Devic disease) is an inflammatory and immunologic disease of the central nervous system that causes demyelination of the optic nerve and spinal cord.

Disease Entity

Neuromyelitis optica (NMO) is an inflammatory disease that causes demyelination of the central nervous system, primarily affecting the optic nerve and the spinal cord. [1] [2]

Etiology

An exact cause of NMO is unknown. An autoimmune phenomenon has been attributed as the etiology of this entity, however, there is no evidence that confirms it entirely. There was initially debate of whether this represents an extension of multiple sclerosis (MS) or an independent pathology. [3]

Risk Factors

The most important risk factors are; female gender (incidence is 10 times higher than in men), Asian and African ethnicities, Ebstein Barr virus seropositivity, and a negative history of smoking. [4]

General Pathology

Segmented demyelination and inflammation of the spinal cord and the optic nerves inducing axonal loss and perivascular lymphocytic infiltration.

Pathophysiology

There is a specific autoantibody in NMO. It is an IgG antibody against Astrocytic Aquaporin 4 (AQP4). AQP4 is a water channel membrane protein. An insult to this protein causes locally water imbalance which results in oligodendrocyte damage, causing demyelinization. [1]

Diagnosis

History

The first association between myelitis and optic nerve disorder was reported in 1870 by Sir Thomas Clifford Allbutt. His case reports were vague and no pathology was documented [5]. Almost 80 years later, Stansbury published a thorough review on NMO and afterwards accepted as a separate entity from MS. [3]

Physical examination

Ophthalmologic examination may be within normal limits, but optic atrophy and disc pallor can be present. Central nerve cavitation can be formed as a result of demyelinization and necrosis in more severe cases [6]. Spinal cord involvement manifestations are paraparesis or tetraparesis as well as sphincter dysfunction seen; magnetic resonance imaging (MRI) is usually performed in the presence of these signs to exclude spinal compression [5][6]. About 30% of the patients have a positive Lhermitte’s sign in patients with recurrent disease. [6]

Signs and symptoms

Approximately 30% of the patients present with a flu-like illness with symptoms such as; fever, myalgia, and headache. Afterwards, more specific signs and symptoms start to develop in a two-week period that affects sensory and motor pathways. Later, unilateral or bilateral ocular pain, acuity and color disturbances, phosphenes, as well as central scotomas start affect the patient secondary to the optic neuropathy. [6] There is no additional neurologic involvement aside of the spinal and ophthalmologic phenomena. Weeks after the initial insult, symptoms start to improve, but usually with residual disability [5]. Over 60% of the cases have a relapsing course [5]. Less commonly brain stem lesions are present, resulting in; nausea, vomiting, vertigo, hypoacusia, trigeminal neuralgia, nystagmus, etc.

Diagnosis

Diagnostic criteria consist of the presence of; optic neuritis and acute myelitis and at least two of the following characteristics:

  • Contiguous spinal cord lesion compromising at least three spinal cord segments
  • Brain magnetic resonance not meeting MS criteria and
  • Positive titers for anti-NMO-immunoglobulin [2][7].

Laboratory test

Oligoclonal bands in cerebrospinal fluid can support the diagnosis of NMO, but cannot distinguish it from MS. AQP4 antibody serum levels are not only specific to NMO, but also correlate with the degree of disease activity. Testing of AQP4 is recommended during an acute attack and before starting immunosuppressive therapy. [6]

Differential diagnosis

  • Multiple sclerosis
  • Acute disseminated encephalomyelitis
  • Systemic lupus erythematosus
  • Neuro- Behçet disease

Management

Initial treatment for patients with suspected NMO or patients with acute attacks is intravenous glucocorticoids. Prevention of recurrent attacks is treated with long-term immunosuppression.

General treatment

Guidelines for NMO management have been difficult to establish, since most studies involve a small number patients. Treatment for acute episodes consists mainly on steroids (methylprednisolone 500-1000mg daily for 5-10 days) and seven cycles of plasmapheresis (55ml/kg), intravenous immunoglobulin has been proposed as an alternative [5]. Long-term management consists of a combination of azathioprine and prednisone. Rituximab has been lately used for refractory cases [6][7].

Medical therapy

Medical follow up

Side effects such as hepatotoxicity, immunosuppression, lymphoma and other malignancies should be evaluated in patients receiving these medications [5].

Complications

Monocular blindness can result in up to 60% of patients with relapsing episodes and 20% in subjects with a monophasic course [6].

Prognosis

Good prognosis factors include; male gender, prompt plasma exchange treatment and preserved reflexes. More studies are needed to obtain a more reliable long-term prognosis. [6]

Additional Resources

References

  1. 1.0 1.1 Morrow, Mark J., and Dean Wingerchuk. "Neuromyelitis Optica." Journal of Neuro-Ophthalmology (2012): 154-66.
  2. 2.0 2.1 Matiello, Marcelo, Anu Jacob, Dean M Wingerchuk, and Brian G Weinshenker. "Neuromyelitis Optica." Current Opinion in Neurology (2007): 255-60.
  3. 3.0 3.1 Seze, Jérôme De. "Neuromyelitis Optica." Arch Neurol Archives of Neurology (2003).
  4. Simon, K., H. Schmidt, S. Loud, and A. Ascherio. "Risk Factors for Multiple Sclerosis, Neuromyelitis Optica and Transverse Myelitis." Multiple Sclerosis Journal (2014): 703-09.
  5. 5.0 5.1 5.2 5.3 5.4 5.5 Pearce, J M S. "Neuromyelitis Optica." Spinal Cord (2005): 631-34.
  6. 6.0 6.1 6.2 6.3 6.4 6.5 6.6 6.7 Sellner, J., M. Boggild, M. Clanet, R. Q. Hintzen, Z. Illes, X. Montalban, R. A. Du Pasquier, C. H. Polman, P. S. Sorensen, and B. Hemmer. "EFNS Guidelines on Diagnosis and Management of Neuromyelitis Optica." European Journal of Neurology (2010): 1019-032.
  7. 7.0 7.1 Cree, Bruce. "Neuromyelitis Optica: Diagnosis, Pathogenesis, and Treatment." Current Neurology and Neuroscience Reports Curr Neurol Neurosci Rep: 427-33.