Amyotrophic lateral sclerosis and motor system disorders
The treatment and therapy of and the research into motor system degenerations is one of the focal points of neurology in Ulm. In the clinical area, we are striving for patient care excellence and an evaluation of therapeutic strategies, be they of a pharmacological or symptomatic nature. Another approach not yet added to the routine set of approaches is an offering of new communication options for ALS patients who have lost of their efferences. In these cases, we collaborate with the Medical Psychology Department of Tübingen University (PD Dr. Kübler, Prof. Birbaumer) and various vendors of communication apparatuses.
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What is ALS?
ALS is a chronic disease of the central nervous system, affecting the part of the nervous system that is responsible for the voluntary control of the skeletal muscles. ALS is a damage to the motorial nervous cells (motorial neurons or motoneurons) in the brain and spinal cord. Note that the motor system part of the nervous system and the muscles form a functional unit. Patients therefore conceive of disorders of the motoneurons mainly as muscular deficiency (loss of power, paresis), atrophy or muscle stiffneses (spastics).
Only by means of neurological examination will the doctor find indications of the underlying disorder of the nervous system. Motor system control of the muscles is quite a complicated process. Basically, two different groups of motor nerve cells are involved. The higher-level cells are located in the cerebral (motor) cortex and are the starting point of a long nerve fibre (axon) which reaches down into the spinal cord. This nerve cell and its axon are referred to as first motoneuron. The axon of the first motoneuron contacts the motor nerve cells in the spinal cord which are referred to as second motoneuron. Long nerve fibres interconnect the nerve cells in the spinal cord with the muscles.
In a case of ALS, both motoneuron, i.e. the first and the second one, are affected in a way that destroys the motor nerve cells. Damage to the first motoneuron causes other problems and symptoms than the destruction of the second motoneuron. To put it simply, the first motoneuron control the lower-level second motoneuron. Damage to the first motoneuron will therefore always result in an impairment of the voluntarily induced fine motoricity. Alternatively, damage to the first neuron may also lead to an uncontrolled, increased activity of the second motoneuron which patients will experience as stiffness (spastics) due to the increased muscle tension. Damage to the second motoneuron will more and more and reduce muscle activation by the nervous system which is symptomatically expressed as muscular deficiency (paresis) or muscular atrophy.
What is a motoneuron disease?
'Motoneuron disease' is a generic term covering a whole group of diseases having in common that the motor nerve cells (motoneurons) are damaged. There are basically two different groups of motor nerve cells. The higher-level cells are located in the cerebral (motor) cortex and are the starting point of a long nerve fibre (axon) which reaches down into the spinal cord. This nerve cell and its axon are referred to as first motoneuron. The axon of the first motoneuron contacts the motor nerve cells in the spinal cord which are referred to as second motoneuron.
The group of motoneuron diseases includes amyotrophic lateral sclerosis (ALS) which is characterised by the function of both groups of nerve cells being impaired. It is also the most common type of motoneuron disease. Other, less frequent, types only affect the first motoneurong (hereditary spastic paraparesis, HSP) or only the second motoneuron (spinal muscular atrophy, SMA, and progressive muscular atrophy). HSP and SMA are usually hereditary illnesses. Cases of all other types of motoneuron diseases are so few and far between that many scientists dispute their being separate diseases.
How does ALS start and what are its symptoms?
In the vast majority of cases, the absolute onset of the disease is characterised by muscular deficiency which may have very different symptoms, depending on the muscles that are initially affected. For example, patients may notice (and about 40% of the patients do) a certain clumsiness in their hands, e.g. when shaving, writing, doing needlework, etc. If the disease begins in the lower extremities (another 40% of the cases), patients will notice some gait disturbance or a weakness in their legs. Other initial symptoms include mucscular atrophy and stiffness of the muscles (spastics). A typical problem at the beginning of the disease is cramping mainly of the calf muscles.
A basic distinction must be made between cases that start in the extremities (spinal onset) and a less frequent progress which begins with speech and swallowing problems (bulbar onset). At first, about 25% of the patients suffer from the bulbar type of ALS. It is possible that others will notice slight changes in the patient's speech before the patient notices it themselves. The important thing to remember is that both, the spinal and the bulbar type have the same cause notwithstanding the differences in the patients' symptoms.
How does the disease progess?
ALS progress differs from patient to patient. It is therefore impossible to predict each of the problems and the time when a symptom will appear. The progress of ALS may be characterised by extreme ups and downs. Very often, the disease begins in the fifth or sixth decade of the patient's life. Only a few patients develop the disease before the age of 40. The muscles that are initially affected substantially determine the progress of ALS and the symptoms experienced by a patient. A basic distinction must be made between cases that start in the extremities (spinal onset) and a less frequent progress which begins with speech and swallowing problems (bulbar onset).
Problems normally begin in a defined muscular region, e.g. in the small hand muscles of an arm. From there, symptoms very often spread to adjacent muscular regions, e.g. going from an arm to the shoulder of that arm or into the other arm. Promotion of symptoms through the motor system obviously follows a certain pattern whose principles, however, have not been found yet. Symptoms may take many months or just a few weeks to spread. Muscular atrophy or stiffness of the muscles (spastics) starts a progessing paralysis of the affected extremity. In cases where the leg muscles are affected, progessing paralysis will result in an increasingly spastic gait ending in the need for a walking aid or a wheelchair. Arm muscle atrophy will inhibit other abilities of the patient, i.e., it will make it increasingly difficult for the patient to perform arm and hand activities such as lifting, carrying, writing, cutting, eating, washing.
In the course of the illness, all extremities (arms and legs) will normally be affected. Everyday activities will then be supported by obtaining technical or medical tools and by the help from relatives and care professionals. In a minority of cases, the onset of the illness is characterised by bulbar symptoms. The vast majority of patients will develop bulbar symptoms at later stages of the illness in addition to previous extremity disabilities. Bulbar symptoms are caused by disorders of the muscles controlled by the cerebral muscles, including the tongue, throath and palatal muscles. Functional disorders of these muscles will inhibit articulation up to a complete disability to communicate verbally. These symptoms are extremely disturbing for the patients and their relatives. Communication aids have been developed addressing these specific problems by allowing patients to communicate without verbalising. Chewing and swallowing problems make patients aware of throat and tongue muscle problems. They will experience difficulties with eating certain food, mainly very tough food or liquids. Such problems can be alleviated by a dedicated diet. Face muscle paralysis may sometimes also occur. Due to the ensuing loss of control over the saliva patients report this symptom to be very disturbing. Appropriate medication may reduce the excessive production of saliva. Muscles are also involved in vital body functions such as breathing. Thus, the relevant sceletal muscles move the chest and diaphragm during the breathing process. A weakness of the breathing muscles may develop into a lethal risk, mainly at later stages of the illness.
How quickly does the disease progess?
This question is unanswerable in itself due to the substantial personal differences in the course of the disease. The average course of the illness takes about three to four years. Note that very slow progressions of ten and more years have occurred in 5% of the ALS patients. A sudden standstill in progress has been reported not often but repeatedly.
Latest figues lead us to assume that optimising pharmacological therapy and care wil extend the patient's life by more than a year without the therapy producing any side-effects. Inserting a percutaneous endoscopic gastrotoma (PEG) and non-invasive respiration at home have also been shown to have a positive effect on the patient's life expectancy.
At what age does the disease begin?
The disease mostly develops between the ages of 50 and 70. Youngest patients have been reported to be between 20 and 30 years old. The average onset is between 56 and 58 years. ALS starts before the age of 40 in less than 10% of the patients.
How frequent is ALS?
ALS is far more frequent than people tend to believe. Between three and eight of each 100,000 persons develop ALS. Two new cases occur each year - again related to every 100,000 persons. ALS frequency is approximately the same all over the world, the only exception being some western Pacific regions where ALS occurs much more frequently. Figures are diminishing there as well, though.
Is ALS a new disease? How long has it been known for?
The disease as such is not new. A clinical description and the name date back to the middle of the 19th century. It was the Paris neurologist Charcot who coined the name, amyotrophic lateral sclerosis, in 1869.
Is the number of ALS cases increasing?
It seemingly is. However, statistical figures confirming the increase should be handled carefully. Thus, demographical changes, e.g. age layering, are probably the most influential factor. Moreover, an increase in the number of ALS cases may be due to improved methods of detection.
Do men take ill of ALS more frequently than women?
Yes, there are slightly more men with ALS than women. The ration is about 1.5:1. Causes of this discretion are not currently known.
How is ALS diagnosed?
A neurological examination yields indications of ALS already. A neurologist will draw conclusions from characteristic symptoms found and suspect the presence of ALS. Depending on how far the syndrome has progressed, diagnostic results will include a mere possibility or go to being very sure. Secure clinical diagnosis requires that all details of the clinical picture are observed, the progress is monitored, and that certain additional examinations are made.
Electromyography is of crucial importance at this point. A physician familiar with electromyography (EMG) will be able to distinguish between the actual muscular disorders and diseases of the motor nerve cells causing muscle function disorders. Basically, this distinction can be used to make a difference between ALS and other neuromuscular disorders. Motoneuron problems lead to characteristic results of electromyography. Again, the reliability and the classification of results depend on how far the patient's ALS has progressed. Thus, diagnosing ALS may be difficult, particularly at early stages of develoment.
Apart from a clinical examination and electromyography, a couple of other diagnostic actions should be taken, including the testing of blood and cerebrospinal fluid and imaging such as NMR tomography, as appropriate. As a matter of fact, these examinations do not aim at detecting ALS but at excluding rare diseased similar to ALS which are normally easier to treat (refer to the question about diseased similar to ALS).
Are there illnesses with similar symptoms as ALS?
Some symptoms characterising the ALS syndrome also occur in other neurological diseases. This is always related to discrete elements of the disease but not to the entire syndrome. Especially at early stages of development, it is important to distinguish ALS from other diseases showing similar symptoms. These illnesses occur much less frequently than ALS and it takes further examinations to distinguish them from ALS. A clear distinction is particularly important because "ALS similations" are often better to cure. Illnesses taken into account by so-called differential diagnostics include a mechanical damage to the spinal cord (cervical myelopathy), illnesses that are somehow related to autoimmune processes (monoclonal gammopathy with blocked conduction and motoneuropathy), or toxic functional disorders. Neurologists are familiar with these diseases and will take the appropriate diagnostic actions if they find but the slightest indication of them. Depending on the actual problem, diagnostic methods will vary and include blood tests, cerebrospinal fluid analysis, and imaging techniques.
Indication for mask respiration at home
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