Primary lateral sclerosis (PLS) and amyotrophic lateral sclerosis (ALS) are rare neurodegenerative diseases that progressively affect voluntary muscle movement over time. However, there is an important difference between the two conditions.
PLS affects only upper motor neurons, develops more slowly, is debilitating, but not fatal. ALS affects both upper and lower motor neurons, occurs more rapidly, causes muscle wasting, and has more devastating effects than PLS.
This article details the differences, symptoms, diagnosis, and treatment of PLS and ALS.
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symptoms
Many symptoms of PLS and ALS are very similar and can be confused with other symptoms early in the disease process. This is because both diseases lead to degeneration and death of the neurons that carry information to and from the brain.
Symptoms of PLS
PLS symptoms take years to develop, while ALS symptoms appear more rapidly. Additionally, those diagnosed with PLS typically continue to live a normal lifespan, while those diagnosed with ALS typically have a life expectancy of 3 to 5 years.
PLS is more common in men than women and typically begins between the ages of 40 and 60. PLS progresses gradually over years to decades.
Common symptoms of PLS are:
- weakness of the legs
- muscle spasms and spasticity
- Difficult to walk
- problem of balance
- clumsiness
- slowing down of movement
- speech or swallowing problems
- Stiffness and weakness starting in the legs and slowly spreading to the torso
Symptoms of ALS
Symptoms of ALS usually do not develop until after age 50. However, symptoms may start early. ALS patients experience loss of coordination and muscle strength that gets progressively worse, eventually affecting more muscle groups.
ALS symptoms eventually reach the point where daily functions such as swallowing, walking and standing become impossible.
Other common symptoms of ALS include:
- weakness in the arms and legs
- Decreased ability to swallow, choking, nausea, and drooling
- difficulty breathing
- Difficulty walking or climbing stairs
- difficult to lift
- Speech problems, such as slurred or slow speech
- Head drop due to weakened neck muscles
- hoarseness of voice
- muscle spasms or stiffness
- weight loss
ALS patients retain cognition. However, in rare cases, people can develop dementia, leading to memory loss.
cause
In most cases, the exact cause of PLS and ALS is unknown and appears to occur randomly.
Causes of PLS
PLS is a genetic disease, caused by a dysfunctional gene known as the genetic variant SPG7. Some people inherit PLS from their parents.
Causes of ALS
Research suggests that genetics and environment play a role in the development of ALS. Over 10 genetic mutations, including the SOD1 gene, have been associated with some cases of ALS.
Environmental factors that may contribute to the development of ALS include:
- Exposure to toxins or other infectious agents
- virus
- physical trauma
- malnutrition
diagnose
Several diagnostic tests help diagnose ALS and PLS. In either case, no single test can provide a definitive diagnosis. Your health care provider will likely begin by gathering your past medical history, performing a physical examination, and gathering information about your symptoms. It may also run additional diagnostic tests not included in the
Diagnostic tests for PLS and ALS may include:
- clinical examination
- neurological examination
- blood and urine tests
- Electromyography (EMG)
- Nerve conduction studies (NCS)
- Lumbar puncture
- Magnetic resonance imaging (MRI) of the brain and spine
- muscle biopsy
- genetic test
- swallowing studies
- Repeat neurologic and diagnostic tests to assess whether symptoms are worsening
Symptoms of ALS begin and worsen much earlier than PLS, so it is easier to diagnose within the first year or two.
process
Proper diagnosis of PLS or ASL is essential, as treatment varies by disease. Unfortunately, there is no treatment that reverses or cures motor neuron damage caused by PLS or ALS. Treatment can help control symptoms, prevent complications, and improve quality of life for people with either disorder.
PLS treatment
Treatment of PLS is usually symptomatic and includes:
- Muscle relaxants to reduce spasticity, including Lioresal (baclofen), Zanaflex (tizanidine), or benzodiazepines
- Analgesics
- antidepressants for depression
- physical therapy
- Occupational therapy and rehabilitation to prevent joint immobility and delayed muscle atrophy
- Assistive devices such as supports and braces
- speech synthesizer
- wheelchair if needed
- Speech therapy if facial muscles are involved
ALS treatment
Because the onset of symptoms progresses more rapidly and is more debilitating, additional supportive care from a variety of providers is essential, including:
- doctor
- pharmacist
- neurologist
- Physical therapist, occupational therapist, speech therapist, respiratory therapist
- nutritionist
- social worker
- clinical psychologist, and
- home care and hospice nurses.
A multidisciplinary team approach helps deliver individualized treatment plans to keep patients as mobile, comfortable and independent as possible.
Medications that help manage the symptoms of ALS include:
- Rirutec (riluzole)): an oral drug thought to reduce damage to motor neurons. Studies show that the drug may help patients live a few months longer.
- Radicava (edaravone): Intravenous drug thought to help slow decline in daily activities
Your health care provider may also prescribe drugs to help:
- muscle spasms
- muscle stiffness
- excess saliva
- pain management
- dimple
- sleep problems
- constipation
Additional devices that can help people with ALS include:
- computer-based speech synthesizer Uses eye-tracking technology to help people with yes or no answers
- Brain Computer Interface (BCI) A system that allows ALS patients to communicate or control devices such as wheelchairs using only brain activity
As ALS progresses, the muscles that help you breathe weaken and you may need additional respiratory support, including:
- Non-Invasive Ventilation (NIV): Oxygen is supplied through a mask over the nose and mouth.
- Respirator (ventilator): A machine inflates and deflates the patient’s lungs.
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prevention
Unfortunately, there is no clear way to prevent PLS or ALS. However, if you have a family history of motor neuron disease, consider talking to a genetic counselor.
overview
Primary lateral sclerosis (PLS) and amyotrophic lateral sclerosis (ALS) are two rare neurodegenerative diseases that progressively affect voluntary muscle movement over time. Although the diseases are similar, they have different symptoms and require different treatments.
PLS symptoms take years to develop, while ALS symptoms appear more rapidly. Additionally, those diagnosed with PLS typically maintain a normal lifespan, while those diagnosed with ALS typically have a life expectancy of 3-5 years her.
A word from Verywell
If you or a loved one has been diagnosed with PLS or ALS, talk to your healthcare provider about your diagnosis and treatment plan. Regular visits to a health care provider are essential to see if symptoms worsen over time and to make a correct diagnosis. Neuromotor disorders are difficult illnesses to live with, but know that there are many treatments and medical professionals that can help you manage your symptoms.