A muscular disease

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By DR Y.L.M.

Getting to understand Stephen Hawking’s medical condition ...

I FEEL very sorry for Stephen Hawking, who is wheelchair-bound and incapable of taking care of himself. What is the disease he has called?

The disease Stephen Hawking has is called motor neuron disease. This is actually a group of disorders involving the nervous system.

In motor neuron disease, the motor neurons, or neurological cells that control your voluntary muscle activity such as walking, lifting your arms, talking, breathing, and swallowing are progressively and slowly destroyed.

Motor neuron disease can occur in both adults and children. It seems to be more common in men than women. In adults, symptoms may appear after 40.


In motor neuron disease, cells that control voluntary muscle activity are progressively and slowly destroyed. – Reuters



But I thought the brain controls my voluntary activity like walking and speaking. What part do these motor neurons play and why are they called motor neurons? Do they have some motor mechanism within them?

The word “motor” here refers to movement, as opposed to “sensory”, which denotes “receiving sensations” or “feeling”. It does not refer to you having a mechanical “motor” in any part of your body!

When your brain decides to move a part of your body to perform an action, such as combing your hair or walking to the toilet, the messages from your brain’s nerve cells involved in movement (called “upper motor neurons”) are transmitted to the nerve cells in your brainstem and spinal cord (lower motor neurons).

The lower motor neurons then transmit the messages further on to your particular muscles in your arms, legs, face, chest, abdomen, throat, and tongue.

Now imagine if your motor neurons are affected in any way. Your muscles will then not be able to move properly.



In motor neuron disease, which motor neurons are involved? Upper or lower?

Either or both can be involved.

When upper motor neurons are affected, the symptoms can be spasticity or stiffness of your limb muscles and highly overactive tendon reflexes.

This means you will find it very difficult to do normal movements like chew or run.

When the doctor does a knee jerk test on you with a tendon hammer, your knee will exhibit a very strong jerk.

When lower motor neurons are involved, not only do your muscles not work properly, they will be gradually weakened, wasted and they may experience uncontrollable twitching (called fasciculations).

Motor neuron diseases are divided into different types. They all have long difficult names which denote the sites affected:

Amyotrophic lateral sclerosis – affects both upper and lower motor neurons. This is the type Stephen Hawking has.

Progressive bulbar palsy – affects the lower motor neurons of the brainstem. This one causes slurring of speech and difficulty in chewing and swallowing. Eventually, you will be unable to eat or speak.

Primary lateral sclerosis – affects upper motor neurons

Progressive muscular atrophy – affects only lower motor neurons in the spinal cord

What causes motor neuron

disease?

Some are inherited, especially those present in children.

But there is also a non-inherited version. No one knows its cause, though some cite environmental causes, poisons, viruses.

Sporadic cases may be triggered by exposure to radiation, lightning strikes or other electrical injury, cancers, or prolonged exposure to toxic drugs or environmental toxins.



So how is Stephen Hawking affected?

Stephen Hawking has Amyotrophic Lateral Sclerosis, which is also called Lou Gehrig’s Disease after the famous baseball player who had it. (He lived before Stephen Hawking.) This is considered classic motor neuron disease.

Symptoms are first noticed in the arms, legs or swallowing muscles. Patients lose strength and the ability to move their arms, legs, and body. There may be spasticity, exaggerated reflexes, muscle cramps, fasciculations, and difficulty in swallowing and forming words. The patient’s speech can become slurred.

That is why Stephen Hawking cannot speak without a speaking aid.

This disease is ultimately fatal because the muscles of the diaphragm and chest wall will ultimately fail to function properly. The patient will then lose the ability to breathe on his own.

This disease does not usually impair the patient’s ability to think, or his personality. Hence Stephen Hawking is still as brilliant as he is. However, recent studies have shown that some patients may have problems in decision-making and memory later.



Is there any treatment?

There is no cure. Treatment can only be for symptoms. There is a drug called riluzole that can prolong the patient’s life, but cannot relieve symptoms.

Other treatments include drugs that reduce spasticity, reduce saliva, decrease pain and depression. Physical therapy is always important.




Dr YLM graduated as a medical doctor, and has been writing for many years on various subjects such as medicine, health advice, computers and entertainment. The information contained in this column is for general educational purposes only. Neither The Star nor the author gives any warranty on accuracy, completeness, functionality, usefulness or other assurances as to such information. The Star and the author disclaim all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.


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