Fayyaz Ahmed, consultant neurologist, Hull and East Yorkshire Hospitals NHS Trust, UK, speaks to NeuroNews about transcranial magnetic stimulation, the systems being studied and the implications of National Institute for Health and Care Excellence (NICE) approval.
What is transcranial magnetic stimulation and what are its indications?
Transcranial magnetic stimulation is a device purely developed for migraine treatment. The device delivers a tiny magnetic wave, very similar to mini-magnetic resonance imaging (MRI), which disturbs the brain and terminates a migraine attack. We know that the migraine generator is located in the stem of the brain called hypothalamus. We also know that people who have a warning before the migraine attack (called aura) do have a rippling wave generated at the back of the brain, which scientists call spreading depression. It has been shown that transcranial magnetic stimulation can disturb these waves and stop the migraine attacks at the stage of aura. It also appears that patients without aura may benefit from this because it might work on the migraine generator in the hypothalamus. There is some form of direct magnetic stimulation through a similar device that has been used in the USA for depression.
How do you see this technology developing in the near future?
The current device is bulky and heavy, although it will fit in a woman’s handbag or a good-sized brief case. However, just like how mobile phone technology progressed, I am sure in a matter of a few years smaller devices will be available that would work smarter. Already a device called Gammacore (ElectroCore) is being investigated in a double-blind placebo-controlled study in patients with cluster headache and migraine; which is much smaller but unlike transcranial magnetic stimulation, it works through stimulating the vagus nerve and is put on the right side of the neck and vibrating signals are applied to terminate a migraine attack.
What does research say about transcranial magnetic stimulation?
A double-blind sham-controlled study on transcranial magnetic stimulation was published in Lancet Neurology in 2010 and showed that 39 patients got better using the device vs. 21 in the sham arm. The blinding was effective as 67% of patients in the sham thought they had the real device vs. 71% of those on the real device who guessed it right. Since then, the post-marketing data on 170 patients that have been submitted for publication and the preliminary results were presented at the International Headache Congress in Boston in 2013. These showed that nearly two thirds of the patients improve both in terms of pain and other symptoms such as nausea, vomiting and sensitivity to light, sound and smell.
NICE has approved the use of transcranial magnetic stimulation, what are the implications of the treatment?
NICE has approved this but it does not mean that the clinical commissioning groups have to necessarily fund it. I feel it will be a shame if this was not granted on the UK National Health Service (NHS) as the manufacturers clearly indicate that they would not ask for any reimbursement in those who have not responded. They will provide the device free of charge with a SIM card valid for three months and only if the patient responds would they ask to be prescribed on the NHS.
