Persistent vegetative state: brain stimulation with laser beams

The public only notices diseases when celebrities become patients: in the spring of 2014, Formula One driver Michael Schumacher fell into a coma for several months as the result of a head injury caused by a skiing accident. These types of accidents show how delicate the brain responds to injuries. Brain stimulation could possibly support the rehabilitation of vegetative patients.


Photo: Anatomy teaching model of the human brain; Copyright: Reitz-Hoffmann

The human consciousness is a function of the human brain. The sleep-wake cycle is controlled by the brain stem; © Birgit Reitz-Hoffmann

Injuries, diseases or undersupply during cardiac arrest cause brain cells to die off and damage brain regions. Patients, who survive acute injury, are initially comatose due to brain damage; they therefore do not maintain consciousness nor are they awake. "There is a state of wakefulness and there is consciousness. A vegetative patient has resumed a sleep-wake cycle due to brain stem activity; however, the patient does not have any consciousness or is just in a minimally conscious state," explains Prof. Stefan Hesse from the Medical Park Clinic Berlin Humboldtmühle.

Consciousness is a cortical function that is tied to the cerebrum’s performance. While we are consciousness, we are able to respond to stimuli, to communicate and to interact with the environment. Hesse is currently testing a new non-invasive brain stimulation method using near-infrared laser. This method can stimulate consciousness of a patient and thus also support the interaction between patient and family members: "Our task force has used the transcranial laser for the first time in the therapy of patients in a persistent vegetative state. The patient's forehead was stimulated externally every weekday for ten minutes for four to six weeks, alertness and consciousness were regularly checked and family members were asked for their assessment."

The laser penetrates two to three centimeters into the brain through the cranial bones. "Here, the high-energy beam stimulates the mitochondria, meaning the powerhouses of the cell to produce adenosine triphosphate (ATP), which works as the energy source of cells," explains Hesse. The energy gain in the cells is meant to promote their regeneration. There are also early successful studies in the U.S. for instance, where the laser is used for acute stroke treatment.
Grafic: Human brain with its front highlighted; Copyright:

© lightwise

Physicians notice longer phases of wakefulness in vegetative patients after treatment. Several patients also develop a minimally conscious state. They could follow a mirror with their eyes for instance and follow simple instructions like "stick your tongue out", "close your eyes" or "open and close your hand" according to the brain researcher. Physicians measure patient development based on the revised coma recovery scale, which is deemed the most reliable tool for clinical observation of coma patients. It enables the assessment of consciousness functions and their allocation to brain stem processes as well as subcortical and cortical processes of the brain.

Family members are also included in assessing the patient. Hesse explains that family members have a very accurate grasp when the patient's responses to a stimulus are getting stronger. He tries to determine this by asking family members three questions: "How do you experience your family member's state of alertness?", "Do you find it easier now to communicate with him/her in some way?" and "Have emotional responses changed?"

Hesse views the results as a small therapeutic success, but the treatment does not change the immobility and the complete need for care of the patient: "The therapy makes communication with family members easier when it pertains to patients in a persistent vegetative state. The therapy does not enable patients to walk again, stand up or use their hands and they do not regain daily living skills. We also noticed that we achieve more in patients with traumatic brain injury with stimulation than in patients who suffered undersupply after cardiac arrest." The researcher also points to epileptic seizures as a possible side effect, as seen in his patients.

This is also, why more studies are necessary for this method. So far, there was just a simple trial with a patient population: "Our findings should give reason to pursue the idea of transcranial laser therapy. We currently cannot make any clear statements on the effectiveness of this therapy. This is why a controlled study with a placebo treatment and authentication by other research groups is absolutely essential," says Hesse.
Photo: Timo Roth; Copyright: B. Frommann

© B. Frommann

The article was written by Timo Roth and translated from German by Elena O'Meara.