Motor Neurone Disease – Definition
Motor neurone disease (MND) is a neurodegenerative disease that causes rapidly progressive muscle weakness and eventually results in paralysis. Specifically, this disease affects nerve cells (motor neurons) that control the muscles that enable to move, speak, breathe and swallow.
MND is also known as Amyotrophic Lateral Sclerosis (ALS) or Lou Gehrig’s disease.
Difference between healthy and affected motor neuron
Augustus Waller an English scientist described the appearance of shriveled nerve fibers in 1850. In 1869, the connection between the symptoms and the underlying neurological problems were first described by Jean-Martin Charcot, who initially introduced the term amyotrophic lateral sclerosis. Amyotrophic comes from the Greek word amyotrophia. a means “no”, myo refers to muscle and trophia means “nourishment, amyotrophia therefore means no muscle nourishment, which describes the characteristic atrophy of the sufferer’s disused muscle tissue.
Epidemiology in world wide
MND is relatively uncommon with an annual incidence of about 2 cases per 100,000 population. Prevalence is about 5-7 per 100,000. General practitioners can expect to see one or two cases in their career. It can occur at any age but is more common in people aged over 50.
The male to female ratio is 2:1. About 5-10% of cases are inherited. The mean age of onset is 43-52 years in familial and 58-63 years in sporadic cases of ALS. Male sex, increasing age and hereditary disposition are the main risk factors.
Types of motor neurone disease
MND can be sub-divided into different clinical forms although there is considerable overlap between the different types. The organs connected with Upper motor neuron (UMN) and Lower motor neuron (LMN) is represented in the below figure.
“Classical” spinal onset MND
The upper and lower motor neurons of the arms and legs are damaged leading to weakness and stiffness
The life expectancy is usually 3 and 5 years
More common in men
Upper and lower motor neuron organs
Progressive bulbar palsy (PBP)
The upper and lower motor neurons supplying muscles of speech and swallowing are affected first, leading to difficulties with chewing, swallowing and speech
Symptoms are like slurred speech and difficulty with fluids
The life expectancy is lower than spinal onset disease
Progressive Muscular Atrophy (PMA)
Only lower motor neurons are affected. This leads to weakness and wasting of muscles, without stiffness
This form is rare and is more common in men
The life expectancy is longer than for “classical” MND
Primary Lateral Sclerosis
The form affects only upper motor neurons. Onset is with stiffness in the legs, with progression to involve the arms, and speech and swallowing
Diagnosis is difficult, and requires observation for at least 3 years
The life expectancy is 10-15 years
Sporadic and Familial MND
Sporadic MND: Sporadic MND is the term used for cases of the disease where there is no family history. If anyone is not aware of family members who has MND then chances are it is sporadic
Familial MND: It is the term used when more than one member of a family has been diagnosed with the disease. This may be within the same generation or passed from one generation to some members of the next
Environmental factors such as toxins associated with water and air
Enormous stress on mind
Unhygienic health conditions
Causes of motor neurone disease
Excitotoxicity: Excess glutamate in the key areas of brain and spinal cord
Deficient neuronal blood supply
Symptoms of motor neurone disease
Loss of grip in hand and arm
Feet and leg trips easily while walking
Change in voice and slurred speech due to loss of neuronal signal to bulbar muscle
Muscle cramp and twitching of weakened muscle
Jerking of arms and legs when it is at rest
Diagnosis and Test
Magnetic resonance imaging (MRI) scan
Electromyography (EMG) – a test where needles are used to measure the electrical activity in muscles
Blood investigation and lumbar puncture
A muscle biopsy is occasionally performed
Nerve conduction test – which is similar to an EMF, except the speed that nerves are able to conduct an electrical signal is measured.
Treatment and Medication
Riluzole- It is an anti-glutamate agent, which inhibits the amount of glutamate released into the brain
Medications such as Phenytoin and carbamazepine are used to treat muscle cramp
Complementary therapies such as acupuncture, reflexology, massage and aromatherapy
Prevention of motor neurone disease
Environmental factors are suspected to cause non-inherited motor neuron disease, however this is still an often debated topic, as researches still can’t provide strong evidences
The best chance to prevent this condition is by removing as much as toxins in living environment as possible, improving hygiene and adopting a healthy lifestyle