It has been nearly a decade since the NMO diagnostic criteria (Wingerchuk., et al) were introduced in 2006 and the concept of NMOSD in 2007. Recently, updated diagnostic criteria for NMOSD were published in Neurology on June 19, 2015, after repeated discussions in the “International NMO Diagnostic Committee”.
Long-term observational studies have found that: (1) there is no significant difference between patients with NMO and NMOSD in terms of biological characteristics, such as clinical manifestations, blood and cerebrospinal fluid test results and MRI features; (2) some patients do not have optic neuritis or myelitis at the initial onset, but only present with typical intracranial lesions of NMO and corresponding typical clinical manifestations, but have subsequent episodes that eventually satisfy the diagnosis of NMO (3) the current immunotherapy strategy is identical for NMO and NMOSD. In view of the above three reasons, the new NMOSD diagnostic criteria eliminate the separate definition of NMO and integrate NMO into the broad category of NMOSD, and further divide NMOSD into two groups, AQP4 antibody-positive group and AQP4 antibody-negative group, and set up the corresponding diagnostic rules respectively.
The 2015 NMOSD diagnostic criteria (Wingerchuk.,et al) are as follows.
l. NMOSD diagnostic criteria for AQP4 antibody-positive.
1. presence of at least one core clinical symptom.
2. a positive result of the AQP4 antibody test (an AQP4 transfected cell-based test is highly recommended)
3. other than other possible diagnoses.
2. Diagnostic criteria for NMOSD with negative AQP4 antibodies.
1. the presence of at least two core clinical symptoms in one or more clinical episodes, and the core clinical symptoms present must meet all of the following requirements.
ü At least one core clinical symptom must be optic neuritis, acute myelitis (which should be long segmental transverse myelitis LETM on MRI), or dorsal posterior pole area syndrome of the brainstem.
ü The core clinical signs present should be suggestive of spatial multiplicity of lesions.
ü Meeting additional MRI requirements (as appropriate).
2. negative for AQP4 antibodies, or unconditionally tested for AQP4 antibodies.
3. except for other possible diagnoses.
Core clinical signs include.
1. optic neuritis.
2. acute myelitis.
3. posterior polar area syndrome: episodes of eructation, nausea or vomiting that cannot be explained by other causes.
4. acute brainstem syndrome.
5. symptomatic episodic somnolence, or acute mesencephalic symptoms with a mesencephalic lesion typical of NMOSD on MRI.
6. cerebral syndrome with a brain lesion typical of NMOSD.
Additional MRI requirements (for patients with NMOSD who are negative for AQP4 antibodies or for whom AQP4 antibodies are undetectable)
1. acute optic neuritis: requires cranial MRI (a) normal or non-specific white matter lesions only, or (b) T2 high signal lesions or T1 enhancing lesions on MRI of the optic nerve, which must be greater than or equal to 1/2 of the total length of the optic nerve, or optic nerve lesions involving the optic cross.
2. acute myelitis: associated intramedullary spinal cord lesions greater than or equal to 3 vertebral segments in length (LETM) or, for those with a prior history of myelitis, the presence of focal spinal cord atrophy greater than or equal to 3 vertebral segments in length.
3. posterior polar region syndrome: a corresponding dorsal/posterior polar region lesion of the medulla oblongata is required.
4. acute brainstem syndrome: an associated periventricular canalicular brainstem lesion is required.
In the author’s opinion, the progressive significance of this latest criterion is that
Still highly dependent on the results of AQP4 antibody assays and specifically states the recommended AQP4 antibody assays: AQP4 transfected cell-based assays are strongly recommended, either as a cell-based assay fixed on a slide or by applying flow cytometry. ELISA is not recommended.
For NMOSD with positive AQP4 antibodies, the diagnostic criteria have clearly been relaxed from the previous ones. This criterion is unprecedented in allowing patients without either optic neuritis or acute myelitis to meet the NMOSD diagnosis as long as they are positive for AQP4 antibodies and have other intracranial lesions at typical sites. The implication is that this allows the time point of NMOSD diagnosis to be shifted forward to allow earlier initiation of disease intervention.
The length of the spinal cord lesion is no longer specified in the diagnostic criteria for AQP4-positive NMOSD. Because it has been observed that NMO can present with short segmental spinal cord lesions, the length of the spinal cord lesion is largely related to the time point of MRI examination.
NMOSD with negative AQP4 antibodies may have more diagnostic uncertainty, so clinical and MRI conditions are also set as strict. AQP4 antibody-negative NMOSD is listed separately so that it can be added to existing diagnostic criteria in the future when potential additional biological markers are identified. Based on the new biological markers (e.g., MOG antibody-positive subgroups) that have been identified in AQP4 antibody-negative NMOSD, the authors speculate that heterogeneous disease subgroups are likely to exist in AQP4 antibody-negative NMOSD.
The term “opticospinal MS” no longer appears in the new NMOSD diagnostic criteria, which was historically used by Asian scholars to refer to “MS” limited to optic nerve and spinal cord attacks. The term “opticospinal MS” is now more widely recognized as NMO.
It is also interesting to note that the optic nerve lesions and spinal cord lesions in NMOSD are both “longer”…. …