Difference Between ALS and PLS

Motor neuron diseases adversely affect the brain and nerves of a person. They strike the upper as well as lower neurons and can last for many years.


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ALS and PLS are two kinds of motor neuron diseases that share many characteristics. However, they have a few differences between them as well.


The difference between ALS and PLS is that both make progress in a diagnosed person at different speeds. An ALS patient is expected to live for up to three to five years while a PLS patient generally has a normal lifespan. While ALS is a fatal disease, in most cases, PLS is not.


ALS is short for Amyotrophic Lateral Sclerosis. It is a disease that affects the nervous system of a person. A patient suffers from muscle weakness as well as degraded physical functionality when diagnosed with ALS.

However, the disease is considered to be rare as it affects less than 1000 people annually. PLS is short for Primary Lateral Sclerosis. The disease affects a diagnosed person much slower than ALS does.

It causes a failure in the nerve cells in the brain that control all the movements of the body. The patients suffer from weakness in their voluntary muscles but live up to a normal lifespan.

Comparison Table

Parameters of ComparisonALSPLS
ProgressionALS progresses at a fast rate in patients.PLS progresses at a slow rate in patients.
LifespanA diagnosed person is expected to live for 3-5 years.A diagnosed person generally lives a normal lifespan.
Motor NeuronALS affects the upper motor neuron as well as the lower motor neuron.Generally, PLs does affect the lower motor neuron of a patient.
Muscle WastingALS leads to muscle wasting.PLS does not lead to muscle wasting.
Bulbar SymptomsBulbar symptoms are more common in patients suffering from ALS.Bulbar symptoms are not as common in patients suffering from PLS.
Other SymptomsALS may cause respiratory failure and pneumonia.PLS does not cause other symptoms such as respiratory failure and pneumonia.
Autoimmune DiseasesAutoimmune diseases are common in patients suffering from ALS.Autoimmune diseases are not as common in patients suffering from PLS.

What is ALS?

ALS or Amyotrophic lateral sclerosis is a progressive disease that affects the nervous system. It strikes the nerve cells present in the brain as well as in the spinal cord. This leads to a loss of muscle control.

This means that the patient is unable to control movements in the limbs. People suffering from ALS are generally expected to live for up to three or five years.

The disease is sometimes also called Lou Gehrig’s disease. This name comes from a famous baseball player who was diagnosed with the disease.

Nonetheless, the causes of the occurrence of ALS are still unknown, though some cases are known to be hereditary. Moreover, ALS does not yet have an effective cure.

However, there are many treatments and medications that slow the progression of the disease. When a person is affected by ALS, the initial stages begin with muscle twitching and weakness of the limbs. Some people even suffer from slurred speech.

Other symptoms that occur thereafter include difficulty in walking or doing other activities, weakness in legs, tripping and falling, clumsiness, weakness in the hands, trouble swallowing, muscle cramps, mood swings and even behavioural changes.

Usually, the disease first hits the limbs and then spreads to other body parts.


What is PLS?

PLS, or Primary lateral sclerosis is another nervous system disease with similar characteristics as ALS. However, unlike ALS, PLS only affects the upper motor neurons of a person.

This leads to the death of nerve cells in the brain which results in the patient not being able to control movement. The disease causes weakness in voluntary muscles such as in the legs, arms, and tongue.

PLS is a rare condition that can attack a person regardless of their age. However, it mostly affects people between the ages of forty to sixty. Moreover, the disease is more likely to affect males than females.

It affects the limbs of a person in the early stages and then spreads to other parts of the body slowly. A patient can live a normal lifespan due to this slow progression.

The causes of PLS are unknown and so is the cure. However, medical experts always try to manage the symptoms of PLS with various treatments and medication.

Initial symptoms of PLS include stiffness, weakness in leg muscles, difficulty in maintaining balance, intermittent muscle spasms, slurred speech and even trouble swallowing.

In later stages, the patient suffers from bladder control problems and pain in the lower back and neck as well.


Main Differences Between ALS and PLS

  1. ALS progresses at a fast rate in patients while PLS progresses at a slower rate.
  2. An ALS patient is expected to live for up to 3-5 years while a PLS patient generally has a normal lifespan.
  3. ALS affects both the upper and lower motor neurons while PLS only affects the upper motor neuron.
  4. ALS leads to muscle wasting while PLS does not.
  5. Bulbar symptoms are very common in ALS patients while PLS patients rarely suffer from it.
  6. ALS may cause respiratory failure and pneumonia while PLS causes no such condition.
  7. Autoimmune diseases are common in ALS patients while they are less common in PLS patients.


  1. https://www.sciencedirect.com/science/article/pii/S1388245710002610
  2. https://n.neurology.org/content/72/22/1948.short
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