The course of ALS is different in every patient. It is not possible to predict the individual symptoms or when they will occur. The disease course and especially the individual symptoms are essentially determined by the muscle region that is affected first. The symptoms usually begin in an isolated muscle region, e.g. with wasting of the small muscles of the hand in one arm or fine muscle contractions (fasciculations).
See video example 1

It is characteristic for symptoms to spread to adjacent muscle regions, e.g. from the arm to the shoulder on the same side or to the other arm. The spread of the motor symptoms appears to follow a certain pattern, the basis of which is as yet unknown. The speed at which the symptoms spread can be many months or only a few weeks. Progressive paralysis of the affected limb occurs due to wasting (atrophy) or stiffness (spasticity) of the muscles. If the leg muscles are involved, this means an increasing disturbance of gait, leading to the need to use a walking aid or wheelchair. Involvement of the arm muscles limits other activities. All the activities that are carried out with the arms and hands, such as lifting, carrying, writing, cutting, eating and personal grooming, become more difficult. In the later course of the disease, all the limbs, that is, both arms and legs, will usually be affected.
See video example 2

Carrying out ordinary activities then requires assistance with aids and the help of relatives and care staff.
In a smaller number of patients the disease begins with what are called bulbar symptoms. In the great majority of patients, bulbar symptoms occur at a later stage of the disease in addition to the limb weakness. Bulbar symptoms involve a disorder of the muscles supplied by the cranial nerves. These include the muscles of the tongue, gullet and palate.

Early symptoms are fine muscle contractions (fibrillations) and a reduction in strength or stiffness of the tongue.
See video example 3

Dysfunction of these muscles leads to difficulty with articulation and even to an inability to communicate verbally. Communication aids have been developed for these problems that enable patients to make themselves understood without speaking aloud. The patient notices the disorder of the gullet and tongue muscles because of difficulty with chewing and swallowing. Certain foods, especially very solid or liquid substances, cause difficulty so that a special adaptation of the diet becomes necessary.

Paralysis of the facial muscles, which can also be part of the disease, is a very troublesome experience due to dribbling of saliva. Saliva production can be reduced by appropriate medications. Overall, the bulbar symptoms cause the greatest discomfort for patients and their relatives. Breathing, another elementary bodily function, is also linked to the muscles. During the breathing process, the ribcage and diaphragm are moved by the corresponding skeletal muscles. Weakness of the muscles used in breathing, especially at an advanced stage of the disease, can lead to a life threatening situation and is a frequent cause of death in ALS.

The average survival after the diagnosis has been made is 3 to 5 years. About 10% of patients have a slow ALS course with survival for more than 5 years. A smaller percentage of patients are known to have the disease for more than 10 years. A particularly long disease course is possible in patients with marked involvement of the 1st motor neuron ( predominantly spastic paresis) or primary lateral sclerosis as a specific form of ALS (spastic paresis exclusively). Patients with a juvenile disease onset sometimes have an extremely long disease course of 20 to 30 years.

The astrophysicist Steven Hawking, born in 1942, is a prominent chronic juvenile ALS patient who developed ALS in 1962 at the age of 20 years. Since 1985 his breathing has been assisted following tracheotomy (an incision in the windpipe). One patient with juvenile onset ALS at the age of 24 years (1956) attends our clinic. When seen for follow up in 2003, he had had the disease for 47 years and so far has not needed assisted respiration or feeding.
It should be stressed that it is not possible to estimate the prognosis at the onset of the disease. There is currently no clinical criterion (e.g. laboratory test, genetic factor) that would allow the prognosis of an individual patient to be determined.