Mayo Clinic doctors perform thorough evaluations to rule out other nervous system (neurological) conditions that have similar signs and symptoms as neuromyelitis optica (NMO). Distinguishing NMO from multiple sclerosis (MS) and other conditions ensures that you receive the most appropriate treatment.
To diagnose your condition, your doctor will review your medical history and symptoms and perform a physical examination. Additional studies may include:
Blood serum tests. In blood serum tests, doctors will test for the antibody NMO-IgG, which helps doctors distinguish NMO from MS and other neurological conditions. Mayo Clinic researchers discovered this antibody, which is a specific marker for NMO.
Your doctor can find this antibody by examining your blood sample, and, in some cases, your spinal fluid. This test helps doctors make an early diagnosis of NMO.
Lumbar puncture (spinal tap). During this test, your doctor will insert a needle into your lower back to remove a small amount of spinal fluid. Doctors test the levels of immune cells, proteins and antibodies in the fluid. This test may help your doctor differentiate NMO from MS.
In NMO, the spinal fluid may show markedly elevated white blood cells during NMO episodes, greater than normally seen in MS, although this doesn't always happen.
Evoked potentials. Evoked potentials, also called evoked response tests, test your brain's response to stimuli such as sounds, sights or touch. Doctors attach small wires (electrodes) to your scalp and, in some cases, your earlobes, neck, arm, leg and back. Equipment attached to the electrodes records your brain's responses to stimuli.
These tests help your doctor to find lesions or damaged areas in the nerves, spinal cord, optic nerve, brain or brainstem.