Humans and Health

Completely Paralysed Patients Able to Communicate Again

Motor Neurone disease (MND) was catapulted into the public eye some years ago by revolutionary physicist Prof. Stephen Hawking who suffers from the most common type of MND, amyotrophic lateral sclerosis (ALS). ALS causes a progressive loss of the patient’s motor control; that is, they are unable to control the movement of their muscles.

The patient becomes gradually less able to control their muscles until they are eventually paralysed, a state termed ‘locked-in’. In this state, the patient retains only the finest of muscle movements, like that of the eyes. Despite a loss of motor control, the patient’s consciousness remains intact.

Therefore, there is an ongoing effort to enable the conscious mind of the patient to communicate with the outside world. This is possible in locked-in patients as their eye movements, or cheek movements in Prof. Hawking’s case, are harnessed by a computer system which translates these fine movements into words.

Unfortunately, some locked-in ALS patients progress to an even more debilitating state; completely locked-in state (CLIS) whereby they are unable to move any of their muscles at all. This presents the challenge to scientists of somehow deciphering the patient’s thoughts to allow them to communicate.

“This measuring equipment is connected to a computer which narrows down the thoughts into a simple yes or no response”

This challenge was met by Ujwal Chaudhary’s team, who have developed an ingenious means of communication for CLIS patients, involving looking directly into the brain. Obviously, the technique used to view the brain (termed functional near-infrared spectroscopy, or fNIR) is governed by incredibly complex principles on the border between physics and neuroscience.

The technique relies on the concept that different types of blood absorb different amounts of light. Deoxygenated blood (blood which is no longer carrying oxygen) absorbs more light than oxygenated blood (blood carrying oxygen). Measuring the amount of light that is absorbed by the blood indicates which areas of the brain have used oxygen.

Working brain tissue respires, thereby using oxygen and leaving it surrounded by deoxygenated blood. By looking at which brain areas have been working, the equipment can decipher what the patient has been thinking.

This measuring equipment is connected to a computer which narrows down the thoughts into a simple yes or no response. This enables patients to answer yes or no in response to questions.

Although only being able to answer yes or no seems incredibly restricted, it has enormous consequences for the involvement of the patient in decisions. One such decision is whether to switch their life support machine off, which has previously sparked major ethical controversy over who is entitled to make it. Allowing the patient to decide for themselves eases the pressure on both the medical staff and the patient’s family, who would have previously been faced with that impossible choice of life or death.

This revolutionary technology will vastly improve the quality of CLIS patients’ lives as they will now be able to communicate with their loved ones. Ujwal Chaudhary’s team have provided patients with the ability to make life-changing decisions, by communicating simple responses we take for granted each day.

Josie Clarkson

Image courtesy of Jeremy Brooks

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