You do not have to consult a private neuro (and probably pay £200 for that!) to find out whether there would be any additional options open if you were willing and able to pay.
Most neuros work in both private practice and the NHS (I see on the NHS the self-same one I first saw on BUPA - he referred me to himself!) so any decent neuro will know if there’s anything in the private sector has anything to offer, that the NHS wouldn’t/couldn’t.
It would still be unethical of the neuro to ignore his own assessment of the risks v. benefits, and prescribe something just because the patient wants it. He would have to be satisfied the riskier treatment was justified by the seriousness of the patient’s condition - which doesn’t seem likely, here.
I do think terminal cases are slightly different (I don’t know, but am guessing, your acquaintance was dying of cancer?) The risk/benefit analysis is not as morally complex, since there is little real harm that can be done to someone who has very limited life-expectancy anyway - although if things didn’t work out, there’s always the risk of shortening their life still further, or degrading their remaining quality of life.
For the vast majority of MS patients, it’s NOT a life or death issue, so it would be much harder for a consultant to make the ethical case for a treatment that has not been endorsed as “appropriate” to the patient’s condition. Also, with cancer drugs - particularly those that have the potential only to prolong life in “untreatable” cases, cost is much more of a factor.
Obviously, to the patient and their family, an extra fortnight or month is priceless. But if it’s bought with £20K of NHS money, is that good value for other NHS patients? So much money, so little change to the outcome? There may be no clinical debate that the £20K could buy a small reprieve, so the ethical issue is not: “Are the risks worth it?”, but whether public funding is appropriate.
I think that’s a very different case from the MS patient who wants a more radical (and riskier) DMD than their disease course would usually indicate.
I think this is all going to prove academic anyway, as the cost will mean paying privately isn’t a realistic option, even if you could find a neuro to back you. Morbid though it seems, a difference with the cancer cases is that the patient/family will not face funding it indefinitely, as nature will take its course. How would you feel if you were able to fund Tysabri for six months, but then your money ran out? Would you feel worse at having to stop, than if you’d never taken it in the first place?