Wat is ALS?

In people with ALS, motor neurons in the spinal cord, brainstem and brain gradually die. These nerve cells control the muscles in the body. As the motor neurons become less able to send signals to the muscles, muscle weakness progressively develops.

ALS can develop at any age in adulthood, but it most commonly develops between the ages of 40 and 60. In Europe alone, around 40,000 people live with ALS. Worldwide, 175,000 people die from ALS each year. There are no major differences in incidence and prevalence between countries or continents, with the exception of some regions in the Western Pacific. Progressive muscular atrophy (PMA) and primary lateral sclerosis (PLS) are related to ALS, but are less common.

Symptomen

The main symptom of ALS, PMA and PLS is progressive muscle weakness and/or spasticity.

Progressive muscle weakness

The first symptoms of ALS often include reduced strength in the arms or legs, or difficulty speaking, swallowing or breathing. As the muscles receive fewer signals from the motor neurons, they gradually become thinner and weaker. The disease causes increasing limitations in daily activities. When the motor neurons have completely died, the brain can no longer control the muscles, resulting in paralysis. The senses (touch, taste, vision, smell and hearing) usually remain intact. The functions of the bowel, bladder and heart are also generally unaffected.

Muscle cramps and spasticity

Muscle cramps usually occur in a single muscle. During a cramp, the muscle becomes visibly tense. Cramps often occur after forceful muscle contraction, particularly when the muscle is shortened. A cramp is acutely painful and often only stops when the muscle is stretched. The muscle may remain sore afterwards, and swelling can sometimes occur.

In healthy people, cramps commonly occur in the calf muscles, foot muscles and hamstrings. In people with ALS and PLS, cramps can also occur in other muscles, such as those in the hands, neck and tongue. As the disease progresses, muscle cramps often gradually decrease.

Muscle stiffness and spasms, also known as spasticity, can also occur in ALS.

Cognitive symptoms

Around half of people with ALS, PMA or PLS experience mild changes in thinking or behaviour. Most people and their families experience little or no impact from these changes. In approximately 5 to 10% of people with ALS, PMA or PLS, the disease is associated with frontotemporal dementia (FTD). FTD is a form of dementia in which significant changes in behaviour are often prominent.