Sorted By Test Name - Mayo Medical Laboratories

NMOER
60796
for neuromyelitis optica. Neurol 2006;66:1485-1489 2. Kerr DA: The lumping and splitting of
inflammatory CNS diseases. Neurol 2006;66:1466-1467 3. Luccinnetti CF, Mandler RN, McGavern D, et
al: A role for humoral mechanisms in the pathogenesis of Devic's neuromyelitis optica. Brain
2002;125:1450-1461 3. Cross SA, Salomao DR, Parisi JE, et al: Paraneoplastic autoimmune optic neuritis
with retinitis defined by CRMP-5-IgG. Ann Neurol 2003;54:38-50 5. Cross SA, Salomao DR, Parisi JE,
et al: Paraneoplastic autoimmune optic neuritis with retinitis defined by CRMP-5-IgG. Am J Ophthalmol
2003;136(6):1200 (abstract)
Neuromyelitis Optica (NMO) Evaluation with Reflex, Serum
Clinical Information: Neuromyelitis optica (NMO, sometimes called Devic disease) is a severe,
relapsing, autoimmune, inflammatory and demyelinating central nervous system disease that
predominantly affects optic nerves and the spinal cord. The disorder is now recognized as a spectrum of
autoimmunity targeting the astrocytic water channel aquaporin-4 (AQP4). NMO spectrum disorders
(NMOSD) may involve the brain and brainstem with symptoms of encephalopathy (particularly in
children). The initial symptoms may be bouts of intractable nausea and vomiting. Magnetic resonance
imaging typically reveals large inflammatory spinal cord lesions involving 3 or more vertebral segments.
During acute attacks, the cerebrospinal fluid contains inflammatory cells, but usually lacks evidence of
intrathecal IgG synthesis. The clinical course is characterized by relapses of optic neuritis or transverse
myelitis, or both. Prior to introducing a serological biomarker for NMO, the disorder was thought to be
confined exclusively to the optic nerves and spinal cord, that the clinical course was monophasic and that
NMO was a subset of multiple sclerosis (MS). The discovery of a highly specific disease marker for
NMO (NMO-IgG/AQP4-IgG) helped to define the full clinical spectrum of NMOSD and to distinguish
these disorders from MS. Attacks are often severe resulting in a rapid accumulation of disability
(blindness and paraplegia). Within 5 years, 50% of patients lose functional vision in at least 1 eye or are
unable to walk independently. Many patients with NMOSD are misdiagnosed as having MS. Importantly,
the prognosis and optimal treatments for the 2 diseases differ. NMOSD typically has a worse natural
history than MS, with frequent and early relapses. Treatments for NMOSD include corticosteroids and
plasmapheresis for acute attacks and mycophenolate mofetil, azathioprine and rituximab for relapse
prevention. Beta-interferon, a treatment promoted for MS, exacerbates NMOSD. Therefore, early
diagnosis and initiation of NMO-appropriate immunosuppressant treatment is important to optimize the
clinical outcome by preventing further attacks. Detection of AQP4-IgG by enzyme-linked immunosorbent
assay allows distinction of NMOSD (65%-77% are positive) from MS (0% positive), and is indicative of
a relapsing disease, mandating initiation of immunosuppression, even after the first attack, thereby
reducing attack frequency and disability in the future.
Useful For: Establishing the diagnosis of an neuromyelitis optica spectrum disorder and distinguishing
one of these disorders from multiple sclerosis early in the course of disease, allowing early initiation, and
maintenance, of optimal therapy
Interpretation: A positive value is consistent with a neuromyelitis optica (NMO) spectrum disorder
and justifies initiation of appropriate immunosuppressive therapy at the earliest possible time. Positive
AQP4-IgG enzyme-linked immunosorbent assay results are > or =5 units/mL. Negative results are or =1:60.
Reference Values:
NMO/AQP4-IgG: