Strokes have been ranked as the leading cause of death after heart disease and the leading cause of severe and long-term disability. So figuring out how people recover from a stroke remains one of the major enigmas in the field of neurology.
What is a Stroke?
A stroke is a condition in which blood clots or ruptured blood vessels cut off the blood supply to your brain.
There are two major types of stroke:
- Ischemic stroke: When a blood clot blocks an artery and cuts off the blood supply to a region of the brain. This type of stroke accounts for a great majority of all strokes.
- Hemorrhagic stroke: When a weakened blood vessel bursts and bleeds into the brain.
As a result, the affected part of your brain doesn’t get enough blood and oxygen. The longer your brain stays deprived of oxygen-rich blood, the greater the detriment of the stroke will be.
What Are the Signs and Symptoms of a Stroke?
Strokes typically affect one side of the body. Signs and symptoms of a stroke depend on the part(s) of the brain involved and include:
- Sudden weakness or weakness that occurs in the face, arm, or leg
- Speech impairment
- Difficulty seeing
- Difficulty swallowing
- Loss of balance or coordination
- Difficulty walking
- Sudden, severe headache
- Impaired sense of touch, temperature, pain, and/or inability to sense the limb’s location
What Are the Current Treatments for a Stroke?
Stroke treatment depends on its type. As a rule of thumb, the sooner a patient receives treatment, the better the outcomes.
In cases of ischemic stroke, doctors use a medication called tissue plasminogen activator (tPA) to break up the clot. An injection of tPA is given through a vein in the arm, preferably within the first 3-4.5 hours. This drug dissolves the clot and opens up the occluded blood vessels.
However, there are several limitations to tPA’s use, calling for emergency surgery to rescue the remaining brain tissue if:
- tPA doesn’t help
- the time window of 3.5-4 hours for giving tPA has already elapsed
- there is a contraindication to tPA’s use
Also, the number of patients who can benefit from tPA is quite limited (2-5%). Hence, strategies like transcranial magnetic stimulation (TMS) are being extensively studied to address stroke symptoms in their initial phases.
How Does TMS Benefit Stroke Recovery?
Mounting evidence supports the safety of using TMS in patients with stroke. In addition, these studies show that TMS increases the chances of post-stroke recovery.
Moreover, it is seen that TMS therapy, in combination with occupational and speech therapies, considerably improves the rate and extent of recovery.
TMS Works at the Cellular Level of the Brain
TMS can non-invasively stimulate the release of factors, particularly the brain-derived neurotrophic factor (BDNF), in the brain of a patient with stroke symptoms. BDNF plays a meaningful role in the recovery and rehabilitation of stroke. Being a growth factor, BDNF can stimulate plastic changes within the brain and help with brain repair. It can thus also foster connections between the ischemic neurons and wire them together, gradually enabling them to fire in concert.
TMS Greatly Improves Motor Function
Typically, a stroke involving the left side of your brain affects the right side of your body and vice versa. This happens because the opposite side of your brain controls each side of your body.
Your body requires a green (go ahead) signal from the opposite side of your brain and a red or ‘no-go’ signal from the same side to move one side of the body. This theory forms the basis of how TMS works to improve motor function in stroke.
After a stroke, the unaffected, healthy side of the brain tends to become overly active to compensate. This causes harm to the damaged side and prevents it from recovering. TMS works by taming the excessively active, healthy portions of the brain that control the uninjured part of the body. The idea is to restrict the uninjured side so the damaged side learns to express itself again.
TMS therapy allows your brain to become more amenable to other therapies, optimizing the odds of your recovery. In this context, TMS is most effective when combined with other rehabilitation strategies for stroke.
In a pilot study at the Rehabilitation Institute of Chicago, stroke patients receiving rTMS displayed remarkable improvements in motor function relative to those in the sham (simulation) group. In addition, at six months, researchers noted profound arm recovery in the rTMS group (80% compared to 50%).
rTMS can specifically improve manual dexterity, which is the ability to coordinate your fingers to manipulate objects efficiently. A meta-analysis revealed the beneficial effects of TMS on hand and finger movements. These included picking up items, writing, or other tasks that require fine motor movements and are often affected by a stroke.
Given its effectiveness, experts are now trying to evaluate if stimulating the brain via TMS prior to rehabilitation could improve motor function in patients with stroke.
TMS Improves Language Deficits
TMS is shown to tweak the brain’s circuits that are in flux. The neurons in the human brain are like electric wires. Targeting them with a magnetic field can fine-tune their behavior, making them either more or less responsive. This theory elucidates the positive effects of TMS on language deficits in patients with stroke.
To test the efficacy of TMS in post-stroke patients with difficulty speaking (aka aphasia), Italian researchers applied BrainsWay’s Deep TMS H-coil over the speech area. TMS therapy was used to stimulate the language area on the right side of the human brain. The results revealed that high-frequency deep rTMS significantly improved naming in patients with post-stroke aphasia.
rTMS Can Improve Difficulty Swallowing (aka Dysphagia)
The primary motor area of the brain represents the muscles associated with swallowing. rTMS treatment targeting this area can stimulate it and help improve post-stroke difficulty in swallowing.