Difference Between ALS and PLS

Amyotrophic Lateral Sclerosis
Amyotrophic Lateral Sclerosis (ALS) is also called Lou Gehrig’s disease after the baseball player who was diagnosed with the disease.  It is a disease of the body’s motor neurons which are the nerve cells in the central nervous system that control muscle movement. It is a fatal disease that progresses rapidly, caused by the loss or death of neurons in the body.

People suffering from this disease initially feel their muscles weaken and disintegrate. In time, he will lose control of all his voluntary movements. He might also experience cramps, stiffness in the affected area, and twitching. This is due to the inability of the upper motor neurons located in the brain to transmit messages to the lower motor neurons located in the spinal column and to the different muscles of the body.

It does not affect man’s five senses and eye muscle control and bladder and bowel functions are not affected. It affects more men than women and is more prevalent in older people. Although 5-10 percent of ALS cases are inherited, most occur incidentally. As the muscles weaken, people with ALS will lose the ability to move arms, legs, and body. Within 5-10 years the symptoms will progress and muscles in the chest wall would fail, causing respiratory failure and the patient will eventually die.

Primary Lateral Sclerosis
Primary Lateral Sclerosis (PLS) is often referred to as a milder case of ALS. It is also a degenerative neurological disorder but unlike ALS, the lower motor neurons are unaffected. The body parts that are initially affected are the leg muscles but it can also start in the bulbar muscles which control speech and swallowing.

The degenerative process is confined to the length of the spinal column, affecting the legs, arms, and the speech and swallowing muscles. Middle aged people are susceptible to this disease, with a few rare cases of affected children. Although there is no known cure for the disease, people with PLS can live for many years with the assistance of wheelchairs and canes.

In PLS, cell bodies do not show any decrease in size or increase in its rounding but cortical neurons shrink more than in ALS.  The area that is affected is the corticospinal system without the involvement of lower motor neurons unlike in ALS wherein lower motor neuron degeneration occurs in all cases.

Summary:
1. Amyotrophic Lateral Sclerosis is fatal, killing an affected person within a few years, while Primary Lateral Sclerosis does not cause death.
2. In ALS both the upper motor neurons and the lower motor neurons are affected while in PLS, the lower motor neurons are unaffected.
3. PLS affects only the speech, legs and arms of the patient while ALS affects most parts of the body excluding the eyes, bladder and a few other parts.
4. In PLS the area affected is the corticospinal system, while in ALS all are affected.
5. In ALS muscle wasting occurs in most parts of the body, while in PLS there is no sign of muscle wasting in the lower body parts.