Being fully awake and alert but trapped in a body that is unableto move or speak must be very frightening and frustrating. Thisis often the situation for patients in the late stages of LouGehrig’s disease (amyotrophic lateral sclerosis or ALS).Now there is new hope that computers may be able to help thesepatients communicate by, in a way, "reading their minds."
In this issue of Neurology, Kübler et al.1 reported thatfour people with severe ALS were able to learn to direct a computerscreen cursor by modifying their brain waves through the useof a brain-computer interface (BCI). ALS is a rare disease thataffects the ability to move and communicate as we usually dowith speaking, gestures, and writing. More information aboutALS can be found on the next page.
A BCI is a computer device that helps a person operate a computerby using systems that measure brain waves rather than usinghis or her hands. Changes in the brain waves are then convertedto systems such as a simple word-processing program.
Brain waves are patterns of electrical brain activity. Braincells can communicate with each other by electricity and chemicalscalled neurotransmitters. The electrical activity of the brainis measured by a test called the electroencephalogram (EEG).For this test, tiny metal discs called electrodes are painlesslystuck to the scalp with gel or paste. These electrodes can pickup the electrical impulses of the brain, which pass throughthe skull. This electrical activity is very weak, so the signalis then enlarged in strength by an EEG machine. The EEG machinecan then display the recorded brain electrical activity on acomputer screen or paper tracing. Brain waves measured by EEGdo not represent a particular thought or movement, but ratherrepresent a summary of brain electrical activity at a recordingpoint on the scalp. You could compare an EEG recording to beingable to look at an ocean and identify that there are big orlittle waves and determine what direction they are coming from,but not being able to pick out one individual wave. Brain wavescan be altered by thoughts of planned action (such as thinkingof moving a hand), without actually moving the hand itself.Trying to convert the ability to think of a movement into actuallymoving a computer cursor is what this study by Kübler isabout.
They worked with four patients with ALS over 3 to 7 months.These patients learned how to use a BCI to adjust a type ofbrain wave to control a computer screen cursor (like most peoplemove with the use of a computer mouse). The patients trainedtheir minds by essentially imagining moving the computer cursor.Electrodes were placed on the scalp above the region of thebrain that governs voluntary movement and were able to pickup brain waves that changed in size depending on whether ornot the patient was imagining the movement. This study useda type of brain wave that was different from what has been triedbefore with ALS patients and which allowed faster movement ofthe cursor.
Enabling these patients to control a computer cursor may allowthem to communicate by moving the cursor to a specific wordor phrase on a computer screen. It also could allow patientsto do other actions than communicating, such as turning lightsoff and on or even using a thought-controlled wheelchair. Itis exciting that these patients may be able to communicate moreeffectively in the future. BCIs are an active area of researchand even more promising developments are expected in the comingyears.
There are many diseases of the nervous system that affect theability to move and result in communication difficulties forthese patients. These include ALS, spinal cord injury, and strokesin certain areas of the brain. Patients with movement problemsfrom these diseases may be able to benefit from brain-computerinterfaces. Having the ability to think but not communicatecan create a difficult and frustrating situation for these patients,their caregivers, and their family and friends. This study showspromising results that a new method of enabling these patientsto communicate may be possible.
ALS is best known as Lou Gehrig’s disease. It is alsocalled motor neuron disease because it affects nerve cells (calledneurons) in the brain and spinal cord that govern strength andmovement. Over time, the arms and legs become progressivelyweaker, eventually leading to total paralysis. The disease alsoaffects nerves involved in speaking, swallowing, and breathing.Therefore, patients will eventually become unable to eat oreven breathe on their own. Despite these devastating problemswith paralysis, most patients will not have major problems withtheir thinking or memory. However, communication does becomea problem because patients eventually will not be able to speak,gesture, or write. For 80% of people, weakness tends to progress,causing death in 3 to 5 years. Some of the signs and symptomsof ALS are shown in the bulleted list below.
ALS can strike anyone and at any age, but it generally occursbetween the ages of 40 and 70 years. An estimated 5,000 peoplein the United States are diagnosed with ALS each year.
ALS usually comes on slowly. The first signs are often arm orleg weakness, problems with speaking or swallowing, muscle twitchesor cramps, loss of muscle mass, tight or stiff muscles, andfatigue. Some people laugh or cry more easily without apparentreason. In time, all muscles involved with voluntary movementare affected. ALS does not affect involuntary muscles, suchas those that control the heart and the digestive system.
There is no specific test to diagnose ALS. Several tests, includingnerve conduction studies and electromyogram (EMG), measure howwell the nerves are working. Excluding other causes of muscleweakness is important.
The cause of ALS is not known. Five to 10% of those with ALShave a family history of the disorder and show a genetic pattern.In this form, offspring have approximately a 50% chance of developingALS. This is called familial ALS.
There is no known cure for ALS, but research is promising. Thedrug riluzole modestly increases survival time. Other potentialtreatments are being studied.
The primary treatment is managing ALS symptoms. People withALS need to take an active role in planning and carrying outtheir treatment. Ideally, physical, occupational, speech, respiratory,and nutrition therapy will be involved. A neurologist is thedoctor best qualified to work with the treatment team.
Learning you have ALS can lead to feelings of anxiety, fear,and depression. It is not unusual to feel overwhelmed or numb.Your family and friends may share these feelings. Your doctor,therapists, and support groups can help you, your family, andyour friends through the difficult times ahead. It is importantto talk about the diagnosis and what it means to you.
Kübler A, Nijboer F, Mellinger J, et al. Patients with ALS can use sensorimotor rhythms to operate a brain-computer interface. Neurology 2005;64:1775–1777.[Abstract/Free Full Text]
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