Which patients should be tested for aquaporin-4 antibodies?
| When to test for aquaporin-4 antibodies† |
| 1. LETM or ≥ 3 contiguous segments of focal cord atrophy on MRI spine |
| 2. ‘Idiopathic’ acute transverse myelitis without MS features |
| 3. Severe unilateral optic neuritis with poor recovery, and/or involving posterior visual pathway, eg optic chiasm |
| 4. Bilateral simultaneous or sequential optic neuritis |
| 5. Intractable nausea, vomiting, hiccoughs without clear explanation |
| 6. Dorsal medullary lesion on MRI brain |
| 7. Diencephalic clinical syndrome |
| 8. Cryptogenic leukoencephalopathy |
| 9. MS apparently unresponsive/worsening after starting MS disease modifying therapies |
| 10. CNS inflammation atypical for MS without CSF oligoclonal bands |
| If initial testing is negative, the sensitivity of AQP4-Ab detection is increased with repeat testing 3–6 months later |
↵†It is reasonable to test for myelin oligodendrocyte glycoprotein antibodies if testing for aquaporin-4 antibodies. AQP4-Ab = aquaporin-4; CNS = central nervous system; CSF = cerebrospinal fluid; LETM = longitudinally extensive transverse myelitis; MRI = magnetic resonance imaging; MS = multiple sclerosis. Adapted from Whittam et al60