Transcranial magnetic stimulation(TMS) for treating and preventing migraine

• transcranial magnetic stimulation (TMS) is a non-invasive procedure
  • aims to treat or prevent migraine episodes in people with acute or chronic migraine (with or without aura)
    • TMS is a neurostimulation tool able to perform painless cerebral stimulation through application of magnetic fields on the scalp
      • magnetic current passes through the scalp and generates a perpendicular electrical current that flows tangentially to cortex generating action potentials in cortical neurons. If given in repeated pulses, rTMS can determine long lasting plastic effects that remain also after the end of the train and depend on the stimulation frequency used: frequencies <=1 Hz (low-frequency rTMS: LF-rTMS) reducing, while frequencies >1 Hz (high-frequency rTMS: HF-rTMS) increasing cortical excitability
        
        
  • TMS is given using a tabletop or handheld device that delivers a predetermined level of magnetic pulse or pulses to the head
  • device is placed on the scalp and either single (sTMS) or repeated (rTMS) magnetic pulses are delivered
    • frequency, intensity, duration and interval times of pulses can be varied
    • treatments can be automatically recorded by the device in an integrated headache diary, which can be used to identify headache patterns and trigger factors
    • patients may continue to use regular medications, including drugs to prevent migraines
      
      
• how effective is this procedure?
  • a multicentre randomised controlled trial (RCT) of 201 patients treated for at least 1 attack of migraine with aura (n=164) with a handheld sTMS device (n=82) or with sham stimulation (n=82 ) reported that pain - free rates 2 hours after stimulation were significantly better with sTMS (39% [32/82]) than with sham stimulation (22% [18/82]; p=0.018)
    • sustained pain-free response rates (with no recurrence and no rescue drug use) significantly favoured sTMS at 24 hours (29% [24/82] vs 16% [13/82]; p=0.0405) and 48 hours (27% [22/82] vs 13% [11/82]; p=0.0327) after treatment
      
      
• what are the adverse effects?
  • TMS and rTMS are generally well tolerated and safe as only minor side effects like transient mild headache or local pain and paresthesias are reported
  • the procedure is to be avoided in patient with skull defect or with pacemaker, cardiac lines, metal in the head (electrodes, stimulation devices) or other apparatus that could be influenced (dislocation, induction of electric currents) by magnetic field
  • caution should be paid in patient with epilepsy, because a risk (even if really low!) for seizure is reported
  • no side effect has been reported in pregnant women treated with HF-rTMS for refractory depression, though; however, giving the lack of enough evidence, rTMS is not recommended in such conditions

NICE have stated that '...Patients should be informed that TMS is not intended to provide a cure for migraine and that reduction in symptoms may be modest...' (1)

Reference:

• 1) NICE (January 2014). Transcranial magnetic stimulation for treating and preventing migraine
• 2) Martelletti P et al. Neuromodulation of chronic headaches: position statement from the European Headache Federation. J Headache Pain. 2013 Oct 21;14(1):86.