Transcranial Magnetic Stimulation (TMS)
- Transcranial Magnetic Stimulation (TMS) is a non-invasive way of stimulating the brain.
- A coil is placed over a specific region of the head. When activated, this produces a magnetic field that stimulates the surface of the brain. Typically a number of pulses (magnetic fields) are applied in quick succession. This is known as rTMS or repetitive Transcranial Magnetic Stimulation
- It is thought that the magnetic fields can induce changes in the circuits of the brain that are responsible for producing symptoms of neurological illness
- rTMS has been studied in depression as was approved by the FDA for this purpose in 2008.
- In depression, the coil is placed over a region of the brain known as the prefrontal cortex. Patients who received treatments for 4-6 weeks showed improved depressive symptoms compared to those who did not receive treatment.
- rTMS is now being studied in Parkinson’s Disease:
- Researchers are investigating whether using rTMS in the same way can improve symptoms of depression in Parkinsons Disease as well. More recently, scientists are now exploring whether applying rTMS magnetic stimulation to a different region can improve the motor symptoms.
- In this case, the rTMS is applied to a region of the brain called the motor cortex (or M1). The M1 region forms part of a circuit that has been implicated in motor control. Ongoing studies are investigating whether rTMS will therefore be able to improve motor symptoms of Parkinson Disease, such as tremor, freezing of gait and balance problems.
rTMS is non-invasive meaning it does not require surgery. It is painless and treatments are administered daily for 2 weeks, each lasting 45 minutes to one hour.
transcranial Direct Current Stimulation (tDCS) and transcranial Alternating Current Stimulation (tACS)
In contrast to rTMS (described above) in which magnetic fields are applied to the brain, tDCS and tACS involves stimulating brain regions with constant, low current.
These treatments are also non-invasive, are cost effective and safe. However, the efficacy of tDCS and tACS remains unclear and are currently under investigation.
The way in which the direct current in tDCS and tACS works in PD remains unknown, but some studies have shown that they may be useful in treating non-motor symptoms (such as depression and cognitive problems).
Page reviewed by Dr. Joash Lazarus, NPF Movement Disorders Fellow, Department of Neurology at Emory University School of Medicine.