Facts about MND
French physician, J M Charcot, first identified Motor Neurone Disease (MND) in 1874. Despite intensive research, the cause remains unknown.
Motor Neurone Disease (MND), also know as Lou Gehrig disease and Amyotrophic Lateral Sclerosis (ALS), is a progressive neurological condition in which the nerves that control voluntary muscles stop working. It is a very challenging condition that attacks the motor neurones, or nerves, in the brain and spinal cord. This means messages gradually stop reaching muscles, which leads to weakness and wasting. MND is progressive and debilitating disease for which there is no cure.
MND can affect how you walk, talk, eat, drink and breathe. However, not all symptoms necessarily happen to everyone and it is unlikely they will all develop at the same time, or in any specific order.
There are currently more than 420 living with MND in Ireland and registered with the Irish Motor Neurone Disease Association.
The frequency of MND is relatively consistent within populations of European extraction. Around one person in thirty thousand develops MND each year. In Ireland, this amounts to around 150 new diagnosis every year.
The term MND describes a group of related diseases affecting the nerves in the brain and spinal cord that tell your muscles what to do. These nerves are known as motor nerves or motor neurones; the words nerves, and neurones mean the same thing. As the nerves become damaged, the muscles they control weaken and waste. The muscles first affected tend to be those in the hands, feet or mouth and throat, depending on which type of the disease it is. It does not generally affect the senses, so sight, smell, touch and hearing tend to remain intact, as do the sphincter muscles that control the bladder and bowel. MND is a progressive, life limiting disease and the rate of progression varies greatly from one person to another.
As yet, there is no specific treatment that will halt the progress of the disease. However, there is a lot that can be done in the way of symptom management and to slow the progression of the disease.
How is it diagnosed?
Usually it is not difficult for a Neurologist to diagnose MND on the basis of the history and signs. Early signs may cause some initial difficulty. There is no specific laboratory test. Sometimes special tests, possibly including a brain and spine MRI, are necessary to exclude other diseases. Usually, electrical tests on muscles and nerves are performed and a lumbar puncture and muscle biopsy may be done.
This is variable from three to five years (or occasionally longer) after onset, depending on the activity of the disease and the particular muscle groups affected.
Types of MND: ALS, PLS and PMA
Most people with MND experience a combination of upper and lower motor neurone degeneration. In Ireland, this accounts for around 90% of people with the condition, and is sometimes termed “Amyotrophic Lateral Sclerosis” (ALS). However, there are a number of very rare forms of the condition, in which there is exclusive involvement of upper motor neurones, or exclusive involvement of lower motor neurones.
When the upper motor neurones alone are involved, the condition is called Primary Lateral Sclerosis (PLS). This condition is rare and is difficult to diagnose in the early stages. Most experts like to wait at least 4 years before they can be certain of the diagnosis.
Similarly, those who have exclusive involvement of the lower motor neurones may have a condition called progressive muscular atrophy (PMA). This is also very rare, and it can be difficult to be certain about the diagnosis. Both PLS and PMA carry a better prognosis (or likely course or outcome) than typical MND (ALS).
Some people have exclusive involvement of their speech and swallowing muscles, a condition called progressive bulbar palsy. This is also very rare, and occurs mostly in older women for reasons that are not fully understood.
Spinal versus Bulbar Onset MND
MND is sometimes classified based on where the first symptom occurs. If the nerves supplying muscles in the arms, legs or trunk are affected first, it is often described as “spinal onset”. Equally, if the nerves supplying muscles of speech or swallow are affected first, it is described as “bulbar onset”. Spinal onset is more common in men, and bulbar onset disease is more common in older women. Some people with MND (around 5%) begin with problems catching their breath, and with difficultly lying down flat. This usually points to involvement of the diaphragm, and is termed “respiratory onset”.
Although it was originally thought that MND was a condition that only affected the motor system, we know now that up to 50% of people will also experience some changes in thinking and behaviour. This is very severe in around 15% of cases. In those affected, there is evidence of problems in multitasking, and in making decisions that require complex planning. A high proportion of these individuals also experience changes in their personality and behaviour. These symptoms can be very distressing for caregivers and family members.
MND presents itself in various ways, depending on the particular groups of muscle fibres which degenerate initially. Wasting and weakness of muscles of the hands, sometimes one side a first, stiffness in the legs with dragging of one leg or the development of marked weakness in the legs may be the initial symptom. Sometimes the muscles of the tongue and swallowing mechanism are affected early, with slurring of speech, difficulty in swallowing and coughing.
The disease may remain relatively stationary for some time or may progress to other limbs, to the tongue and to the breathing muscles. Motor Neurone Disease does not cause bladder or bower symptoms and does not cause sensory, visual or hearing disorders.
Is MND inherited?
Approximately 10% of people diagnosed with MND will have an inherited, or familial, form. This form of MND is extremely rare; the great majority of people diagnosed with MND (85%) have the sporadic form, occurring for no known reason.