What is the Difference Between ALS and PLS?

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Amyotrophic Lateral Sclerosis (ALS) and Primary Lateral Sclerosis (PLS) are both neurodegenerative diseases that affect motor neurons, but they have distinct differences. The main differences between ALS and PLS include:

  • Motor Neuron Affected: ALS affects both upper and lower motor neurons, while PLS primarily affects only the upper motor neurons. Lower motor neuron symptoms include decreased muscle tone and twitches, which are not present in PLS.
  • Progression: PLS typically progresses slowly and may take years to affect mobility, while ALS rapidly progresses to cause severe disability and death within a few years. The average life expectancy of someone with ALS is about three to five years, whereas people living with PLS can generally live normal lifespans.
  • Symptoms: Early signs of ALS can appear similar to PLS, but as the diseases progress, symptoms in ALS become more severe and widespread. PLS can cause disabling symptoms, but it is not considered fatal like ALS.
  • Diagnosis: A healthcare provider will diagnose PLS after a physical examination, a neurological examination, and testing. Diagnostic testing may include imaging studies, which suggest some differences between ALS and PLS. In some cases, a diagnosis of PLS may be changed to ALS if the lower motor neurons become involved later in the disease progression.
  • Treatment: Treatment for PLS and ALS focuses on managing symptoms and providing mobility support, such as using a cane or other assistive devices. Common medications to treat symptoms of PLS include muscle relaxants, antispasmodics, and antidepressants.

Comparative Table: ALS vs PLS

Here is a table comparing the differences between Amyotrophic Lateral Sclerosis (ALS) and Primary Lateral Sclerosis (PLS):

Feature ALS PLS
Motor Neurons Affects both upper and lower motor neurons Affects only upper motor neurons
Progression Rapid, often becomes fatal Slower, usually not fatal
Life Expectancy Average: 3-5 years after diagnosis Normal lifespan, not considered fatal
Symptoms Lower motor neuron symptoms (e.g., decreased muscle tone, twitches) Upper motor neuron symptoms only (e.g., difficulty chewing, swallowing, breathing problems, anxiety, depression, difficulty speaking or forming words)

Both ALS and PLS are motor neuron diseases, but they differ in the rate of progression, life expectancy, and the types of motor neurons affected. ALS affects both upper and lower motor neurons, resulting in a faster progression and a shorter life expectancy compared to PLS, which primarily affects upper motor neurons and progresses more slowly.