Motor neurone disease
Motor neurone disease (MND) is a progressive neurodegenerative disease, but not all people are affected to the same degree.
What exactly is motor neurone disease?
MND is a rare, incurable condition thought to affect around one in 50,000 people. It progressively damages the nervous system, causing the muscles to waste away. This happens when specialist nerve cells stop working properly as the disease progresses.
Motor neurones are found in the brain and spinal cord, so messages are no longer transmitted to the muscles. When muscles aren’t used, they deteriorate and waste away. Scientists are still unsure exactly what causes the motor neurones to stop working properly.
MND can affect adults at any age, but is usually diagnosed in people between the ages of 40 and 70, with around twice as many men affected as women.
What causes MND?
It’s hard to say, because triggers can be either genetic or environmental - or, in some cases, a combination of both. More research needs to be done before precise triggers can be identified.
What are the symptoms of MND?
MND can affect how well you can walk, talk, eat, drink and breathe. Symptoms vary in order and intensity from person to person and not everyone will have every symptom. Although the disease is progressive, meaning it worsens over time, the speed of deterioration can also vary a lot from person to person.
There are several types of MND and, depending on which type a person has, the initial symptoms will be different:
- With limb-onset MND the first symptoms are weakness in the hands, arms and legs, general fatigue and unusual clumsiness, muscle twitches and cramps.
- With bulbar-onset MND the tongue is the first organ affected and speech will become noticeably slurred. The tongue becomes smaller and may twitch. Swallowing becomes more difficult.
- With respiratory-onset MND breathing difficulties are the first sign. Early morning headaches and waking up frequently in the night (due to a lack of oxygen from decreased breathing) are also symptoms.
As the disease progresses, some people suffer from mental impairment with memory loss and difficulty concentrating. This is relatively uncommon and can sometimes be confused with changes associated with ageing.
How is MND diagnosed?
It’s hard to diagnose because the symptoms vary in severity, sequence and manifestation from patient to patient. There are tests that may be recommended but these are not exclusive to the diagnosis of MND and may be an indicator of a different underlying problem.
- A blood test can give a first indication of whether muscle is breaking down, as certain chemicals are produced when this happens.
- Electromyography (EMG) uses fine needles to measure nerve impulses. Muscles which have lost their nerve supply show different electrical activity from healthy muscles. The EMG can be shown as abnormal even in muscles that have yet to be affected. This is a very important test when diagnosing MND.
- Nerve conduction tests use electrical impulses to measure the speed at which your nerves carry electrical signals.
- Transcranial Magnetic Stimulation (TMS) may be carried out at the same time as a nerve conduction test. It is designed to measure the activity of the upper motor neurones.
- Magnetic Resonance Imaging (MRI) scans involve using a coil of wire over the scalp to produce a magnetic field that passes through the brain. This can then be used to inhibit or stimulate different parts of the brain to eliminate other conditions that mimic the symptoms of MND. MRI can’t be used to give a positive MND diagnosis.
- Other tests may be requested if the other clinical findings suggest they could be useful.