Electrical Stimulation

Electrical Stimulation

Electrical Stimulation is a way to deliver electricity directly to damaged areas of the brain. It may help to alleviate depression, recover lost movement, and control the involuntary movements caused by brain injury. There are several types of Electrical Stimulation therapy, each with its own name, which can be confusing. However, the main differences relate to the part of the brain that is being stimulated. For example, Deep Brain Stimulation needs an implant to penetrate below the surface layers. It is most commonly associated with Parkinson’s disease. Cortical Stimulation acts on the layer of grey matter on the outside of the cerebrum. It has been used to treat conditions such as stroke. There are numerous studies investigating the possible applications of these and other forms of Electrical Stimulation therapy. The June 2009 review of The Mayo Clinic reports:

‘Pioneering therapeutic trials to investigate the effectiveness of deep brain stimulation (DBS) in hard-to-treat depression, obsessive-compulsive disorder (OCD) and Tourette’s syndrome are underway at multiple medical centres around the world.’1

Many of the results indicate that Electrical Stimulation is a safe and effective treatment.

Electrical-stimulation

Neural network

The treatment varies, depending on what form of Electrical Stimulation you are experiencing. For example, Transcranial Electrical Stimulation uses electrodes on pads that are placed on the head. This does not require surgery. Cortical Stimulation does need surgery to place a device on the dura, which is the membrane that covers the brain. Deep Brain Stimulation implants a device into the deeper layers of the brain.

In general, the electrical implants carry electrodes that send out energy pulses. These pulses can interfere with signals in specific areas of the brain, e.g. they can ‘turn off’ the signal to shake or tremble. In some cases, the implant is attached to a wire that is connected to a type of pacemaker (external pulse generator). This allows you to control the electrical currents easily and without pain.2 In other cases, two operations might be needed. During the first procedure, doctors place the device in the brain. This is performed under local anaesthetic, while you are awake. During the second operation, they implant the pacemaker under the collarbone, which is done under a general anaesthetic. The two devices remain joined by a wire. Again, you can control the amount of stimulation easily and without pain.

 

  • Possible benefits of Electrical Stimulation for stroke

    Research into the benefits of electrical stimulation is encouraging, particularly in treating pain and tremors after a stroke. Helmi Lutsep, Associate Director of the Oregon Stroke Center, said: “It’s the coolest thing in stroke I’ve seen in a long time.”3 Even though the investigations are not complete, stroke survivors have already shown improvement in the USA and Japan. According to the Japanese Journal of Stroke, brain stimulation can alleviate the pain sometimes associated with stroke and it could help to eliminate the involuntary movements that some stroke survivors experience.

    ‘Complete control of involuntary movements has been achieved by DBS [Deep Brain Stimulation] in many patients (76%) with hemiballism, hemichoreo-athetosis, jerky dystonic unsteady hand, distal resting and/or action tremor and proximal postural tremor. The effects have continued to be seen for the entire follow-up period ranging 1-9 years in our series. DBS is an ideal therapeutic option to control post-stroke involuntary movements due to the reversibility of the procedure, and alterability of anatomical location and extent of stimulation.’ 4

    There is also evidence to suggest that Electrical Stimulation can be used to improve movement after a stroke. In 2006, the Journal of Neurosurgery published a study that showed how Electrical Stimulation could help ‘ischemic stroke survivors regain partial use of a weakened hand. All participants in the study received the same [basic] rehabilitation but one group was treated with Electrical Stimulation therapy as well. Researchers reported that patients treated with Electrical Stimulation ‘improved to a significantly greater degree’ compared to those in the control group:

    ‘Everybody improved to some degree, because even in the subjects who received some rehabilitation, we did see improvement,” Lutsep said. “What the data suggested is those who received the (stimulation) implant improved more.’ 5

    In 2009, the Proceedings of the National Academy of Sciences included a study on the effect of mildTranscranial Direct Current Stimulation (tDCS) on a group of stroke survivors. This form of brain stimulation uses a mild electrical current, which is passed through electrodes placed on the head. It affects the outer layers of the brain. In this case, researchers stimulated the primary motor cortex, the part of the brain that controls movement. They asked the participants to play a computer game for five consecutive days. One group was given 20 minutes of Transcranial Direct Current Stimulation. The other group received a 30-second burst of ‘sham’ stimulation. They found:

    ‘People who receive a mild electrical current to a motor control area of the brain were significantly better able to learn and perform a complex motor task than those in control groups. The findings could hold promise for enhancing rehabilitation for people with traumatic brain injury, stroke and other conditions.’ 6

  • Arguments against using Electrical Stimulation for stroke

    Some forms of Electrical Stimulation may have potentially serious side effects. The Department of Neurological Surgery at the University of Pittsburgh identified three types of side effect that could follow Deep Brain Stimulation:

    ‘Some of these side effects are related to placement of the electrode into the brain, some are side effects related to the hardware and its components, and some are due to stimulation of the brain.’7

    They list a range of side effects, including potentially fatal bleeding in the scalp and brain when the device is being implanted, a 3-5% risk of wound infection, and the device breaking down. They go on to state the following:

    ‘In some patients stimulation could improve walking, but cause side effects related to arm or leg function. Some side effects could include numbness of the face, arm hand or leg, stiffness or weakness of the limb, double vision, closure of the eyelids, change in mood, thinking problems, facial weakness, dizziness, light headedness, or imbalance. The stimulator can usually be adjusted to treat these effects. In some patients, stimulation benefits occur together with some side effects.’ 8

    Induced aphasia therapy

    Neural network

    Another problem is that one promising investigation into Electrical Stimulation for stroke was conducted by Northstar Neuroscience. They carried out the EVEREST trial, which was a large scale follow-up to encouraging preliminary trials. However, the company closed after the trial failed to meet its objectives. There has been a great deal of controversy and speculation that they tried to ‘rush’ their Renova device to market. These events have also sparked debate about the design criteria of future trials on Electrical Stimulation therapy. 9

  • Case histories

    Deep brain stimulation for Parkinson’s Disease

    This video discusses Parkinson’s disease. The mechanism is similar to many cases of stroke symptoms, e.g. dealing with tremors.


  • Notes and references
    1. ‘Mayo Clinic Proceedings Reviews Deep Brain Stimulation to Treat Psychiatric Diseases’. Reuters: Mon Jun 29, 2009
    2. Deep Brain Stimulation at The Medical College of Wisconsin’ Medical College of Wisconsin: Neurology: 28 Feb 2008
    3. ‘Electrical Stimulation Boosts Stroke Recovery, Study Shows’. In Science Daily, Mar. 23, 2006
    4. ‘Control of post-stroke involuntary movement by deep brain stimulation and implantable pulse generator’. By Katayama Yoichi (Nihon Univ.). In Japanese Journal of Stroke. Vol.24, No.3; Page 363-365 (2002).
    5. ‘Electrical Stimulation Boosts Stroke Recovery, Study Shows’. In Science Daily, Mar. 23, 2006
      a) This study was followed by the EVEREST study conducted by Northstar Neuroscience in more than 16 sites around USA. This trial ended in controversy, so we have not included their results.
    6. Motor Skill Learning May Be Enhanced By Mild Brain Stimulation’. In Science Daily, Jan. 20, 2009. Retrieved November 11, 2009.
    7. Deep Brain Stimulation’ by Center for Image-Guided Neurosurgery, Department of Neurological Surgery, University of Pittsburgh website.
    8. Deep Brain Stimulation’ by Center for Image-Guided Neurosurgery, Department of Neurological Surgery, University of Pittsburgh website.
    9. ‘Invasive cortical stimulation to promote recovery of function after stroke: a critical appraisal’ by Plow EB, et al. In Stroke 2009 May;40(5):1926-31. Epub 2009 Apr 9.

Aviva Cohen is the author and CEO of Neuro Hero