There is no single test that confirms a diagnosis of primary lateral sclerosis (PLS). PLS can have symptoms similar to other neurological diseases such as multiple sclerosis and ALS. For this reason, you'll likely need several tests to rule out other diseases.

A health care professional first takes a careful record of your medical history and family history and performs a neurological exam. Then you may have the following tests:

  • Bloodwork. Blood tests check for infections or other possible causes of muscle weakness.
  • MRI. An MRI or other imaging tests of your brain or spine might reveal signs that nerve cells have broken down. An MRI also can show other causes of symptoms, such as structural problems, multiple sclerosis or spinal cord tumors.
  • Electromyogram (EMG). The test evaluates the electrical activity of muscles when they contract and when they're at rest. This test also measures the involvement of lower motor neurons. This can help tell the difference between PLS ⸺ an upper motor neuron disease ⸺ and ALS, which affects both upper and lower motor neurons.

    During an EMG, your doctor inserts a needle electrode through your skin into different muscles.

  • Nerve conduction studies. This test can determine if you have nerve damage. A low amount of electrical current measures your nerves' ability to send impulses to muscles in different areas of your body.
  • Lumbar puncture, also known as a spinal tap. A spinal tap can help rule out multiple sclerosis, infections and other conditions. A thin, hollow needle inserted into your spinal canal removes small samples of cerebrospinal fluid. This is the fluid that surrounds your brain and spinal cord. The samples are then analyzed in a lab.

Sometimes it takes 3 to 4 years before a diagnosis can be made. This is because early ALS can look like PLS until other symptoms surface a few years later. You might be asked to return for repeat EMGs over 3 to 4 years before a PLS diagnosis is confirmed.

Genetic testing may be done when juvenile PLS is suspected. Genetic counseling also may be recommended.


There are no treatments to prevent, stop or reverse primary lateral sclerosis. Treatment focuses on relieving symptoms and preserving function.


You might take medicine to relieve these symptoms:

  • Muscle spasms, known as spasticity. Muscle spasms may be relieved by baclofen (Fleqsuvy, Ozobax, Lyvispah), tizanidine (Zanaflex) or clonazepam (Klonopin). These medicines are taken by mouth.

    If muscle spasms aren't controlled with oral medicine, your health care professional might recommend surgery to implant a medicine pump. The pump delivers baclofen directly to the spinal fluid.

  • Emotional changes. You may be prescribed an antidepressant if you have frequent, rapid and intense shifts in emotions.
  • Drooling. Drooling may be helped by amitriptyline or other medicines.

Physical and occupational therapies

Stretching and strengthening exercises can help maintain muscle strength, flexibility and range of motion. The exercises also may help prevent joint immobility.

Speech and language therapy

Speech therapy might help with communication and swallowing if your facial muscles are affected by PLS.

Nutrition support

If you have trouble chewing and swallowing, a dietitian can offer diet tips, nutritional supplements or special feeding methods. This can help you maintain your body weight when symptoms make it hard to eat.

Assistive devices

As PLS symptoms get worse, you may need an assistive device. Physical or occupational therapists may evaluate you regularly to determine whether you need a brace, cane, walker or wheelchair. Assistive technology devices also may help with communication.

Clinical trials

Explore Mayo Clinic studies testing new treatments, interventions and tests as a means to prevent, detect, treat or manage this condition.

Coping and support

It's expected to have a range of emotions when you have primary lateral sclerosis. To cope with the disease and its effects, consider these tips:

  • Seek emotional support. Family and friends can be great sources of comfort and support. It might help to see how others cope with the disease by joining a support group. Because PLS is not common, it might be a challenge to find a local support group. But some online discussion groups are available. Your health care team may have suggestions.
  • Get professional help if you need it. Living with a chronic illness can feel overwhelming at times. Seek professional counseling for another point of view or if you have depression and need advice on treatment.
  • Know and use resources available to you. If PLS is restricting your activities, ask a health care professional about devices designed to help you stay independent. Social services also works with people with disabilities of all kinds. Try to learn all you can about the resources available to you. Sometimes relying on your community for help can strengthen ties in new ways.
Sept. 20, 2023
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  4. Primary lateral sclerosis. Genetic and Rare Diseases Information Center. https://rarediseases.info.nih.gov/diseases/10684/primary-lateral-sclerosis. Accessed May 11, 2023.
  5. Juvenile primary lateral sclerosis. Genetic and Rare Diseases Information Center. https://rarediseases.info.nih.gov/diseases/4485/juvenile-primary-lateral-sclerosis. Accessed May 11, 2023.
  6. Jankovic J, et al., eds. Disorders of upper and lower motor neurons. In: Bradley and Daroff's Neurology in Clinical Practice. 8th ed. Elsevier; 2021. https://www.clinicalkey.com. Accessed May 11, 2023.
  7. Cifu DX, et al., eds. Motor neuron diseases. In: Braddom's Physical Medicine & Rehabilitation. 6th ed. Elsevier; 2021. https://www.clinicalkey.com. Accessed May 11, 2023.
  8. Adam MP, et al., eds. ALS2-related disorder. In: GeneReviews. University of Washington, Seattle; 1993-2023. https://www.ncbi.nlm.nih.gov/books/NBK1116/. Accessed May 11, 2023.
  9. Miceli M, et al. ALS2-related motor neuron diseases: From symptoms to molecules. Biology. 2022; doi:10.3390/biology11010077.
  10. De Boer EMJ, et al. Genetic characterization of primary lateral sclerosis. Journal of Neurology. 2023; doi:10.1007/s00415-023-11746-7.
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