A patient presenting with optic neuritis or a brainstem syndrome usually gets a brain MRI. Two further investigations change what you can tell them, and both are often skipped because the diagnosis already seems clear.
Image the spinal cord. Asymptomatic cord lesions are common at a first attack, they contribute to dissemination in space, and cord involvement carries prognostic weight independent of the brain. A patient with a normal-looking brain and two cord lesions is in a different position from one with neither, and you will not know unless you look.
Send CSF for oligoclonal bands. They shorten the route to a McDonald diagnosis, and they also carry prognostic information about the course. A lumbar puncture is a harder conversation at the second visit than at the first, when the patient is already in hospital and already frightened enough to accept it.
Both investigations are cheaper and more available than most of what follows them, and both become much harder to obtain once the patient is well again and the episode is receding.
- Image the whole spinal cord, not only the symptomatic level
- Send CSF oligoclonal bands at the first attack rather than deferring
- Record lesion counts numerically in the report request and the notes
- Document attack topography explicitly — it carries prognostic weight
- Do both while the patient is still in hospital; uptake falls sharply afterwards
Why it matters
The information that drives a prognostic conversation years later has to be collected in the first few weeks or not at all.
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