4 Tests That Help Diagnose ALS


There isn’t one test that doctors can use to determine if a person has amyotrophic lateral sclerosis (ALS). Instead, doctors need to perform a series of tests to eliminate other similar neurological diseases and to arrive at an ALS diagnosis. The process can be slow, taking an average of 12 to 14 months in the U.S. The patient will be told that they have suspected, possible or probable ALS which will depend on the parts of the body affected. It’s only as the disease progresses that doctors will know more.

According to the ALS Therapy Development Institute, doctors assess a patient’s physical symptoms, along with taking simple blood and urine tests and a spinal tap.

To rule out other neurological disorders, they may also run the following tests:

Electromyography (EMG) and nerve conduction studies (NCS)
These two tests will allow doctors to see if the motor nerves  are still working correctly or if they’ve degenerated. NCS tests the strength of the signals that motor nerves can send to the muscles and EMG measures how the muscles respond to signals from the motor nerves. The tests help to eliminate other disorders, particularly ones affecting the peripheral nerves.

Join our ALS forums: an online community especially for patients with Amyotrophic Lateral Sclerosis.

Muscle biopsy
A muscle biopsy will allow a doctor to investigate specific muscles the patient is experiencing difficulties with. The tissue will then be studied under a microscope to rule out other neuromuscular diseases.

MORE: An overview of the signs and symptoms of ALS

MRI scan
Magnetic resonance imaging (or MRI) can look at the tissue in the spinal cord and brain, helping to rule out conditions such as multiple sclerosis and brain tumors as well as diseases of the spinal cord.

Genetic testing
Around 10 percent of ALS cases are genetic. If there is a family history of the disease, doctors may order genetic tests to see if the patient has one of the nine identified mutated genes associated with ALS.

MORE: Explaining the progression of ALS

ALS News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or another qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.

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  1. Larry Berg says:

    Explain to me what the purpose of this article is considering that those of us with ALS already know this.

    • Ashley says:

      I don’t have ALS, and specifically googled how they test for ALS. This was the first site that came up.

  2. Laurie Taylor says:

    Other websites include a lumbar punch test. What tests are carried out with the spinal fluid and what mimics or conditions does it rule out.

  3. Susan Alley says:

    I have almost every symptom as if I were on the meds, and have not even been diagnosed yet everyone, including myself, knows I have ALS.The problem is I have been waiting for 6 months to get diagnosed! I am on a so called “emergency” wait list in Nebraska. My appointment is Sept.5,2018, which I scheduled 4 mos. ago, have called the office twice now and tried to move it up with no luck and have a pre-diagnosis from my M.D. which means nothing, because as we all know, it has to come from the neurologist.

  4. Cecil Marble says:

    I have burning muslces spasms cramping inside right leg numb feels like nerve damage down to my ankle had two knee replacement surgery on my right knee and several surgeries after have to go get this implant taking out because it bad but I burn so bad and nerve pain very bad

  5. Peter Ferguson says:

    I was diagnosed relatively quickley. At a special multi disciplinary ALS clinic at Toronto’s Sunnybrook Hospital. They used several of the tests outlined.

    • Christine Moore says:

      I have been waiting 9 months to see an neurologist I have yet to wait another 2 months for my appointment in July. I am deteriorating rapidly, have difficulty walking,. I have to hold onto stair railings going up stairs and feel like someone is pushing my back down. I have constant muscle twitching throughout my body. I cannot go up on my toes anymore, impossible. I was a strong active individual who feels like my whole life has been ripped away from me. How did you get into the ALS clinic so quickly? No one is taking me seriously!

      • Tori says:

        Christine, what state are you in and what is your insurance? This will often determine how quickly you get in to see a neurologist. If you have a plan with only one or two in network neurologists, that explains why it is taking so long. If you have Medicaid or Medicare for insurance, you have a very limited plan as it is. Call your State Representative. They can often help.

  6. Mary says:

    I had a emg showing one abnormal muscle in hand no other abnormality in other muscles but say its a wait and see game v stressful have all symptoms thou seen another neurologist in two weeks desperate time

  7. April says:

    I’m in the diagnostic process. A year ago I had a normal EMG and only “mild carpal tunnel” as per NCS. I have had muscle cramping in weird places and twitching all over. My gait has changed and I feel as if I have lost a tremendous amount of power and endurance. I now have an abnormal Neuro exam with clinical weakness and reflex asymmetry. I have MRIs of my cervical and lumbar spine Monday, as well as a stack of labs. My EMG/NCS is Thursday. I’d be lying if I said that I’m not afraid. I don’t know if the Neuro doing the EMG will tell me anything, or if I will have to wait for my follow up appointment which isn’t for another month.

    Any thoughts are welcome.

    • Rick says:

      I have had numerous autoimmune like conditions and positive test results for the last four years. I started having hand weakness and loss of dexterity a few years ago, but no one thought anything of it. My legs buckle, my arms are weak, my hands are weak and I feel like I’m getting weaker every day. I’m getting MRIs with and without contrast in 9 days. I now suspect ALS because of the rapid onset of weakness and lack of diagnosis of anything else. I’ve been to 30 doctors in the last 4 years and no diagnosis of anything. I wish you the very best. You’re not alone in this.

      • Deb says:

        If you do a bit of research on gut microbes, there’s tons of research showing there is a serious dysbiosis in ALS. So, being obsessed with trying to do something about ALS, I recently came across this test, https://www.diagnosticsolutionslab.com/tests/gi-map, and seen the results in one pALS and massive zonulin, which the mouse models are showing that happens ahead of neurological symptoms. Additionally, this test shows Akkermansia, clostridia and faecalibacterium, all of which are helpful microbes, and it shows a couple problematic microbes, methanobacteriaceae and fusobacterium. Search Akkermansia on the ALStdi forum for more information about why you might want to know how this microbe is doing in your body. The clostridia help with serotonin production and serotonin is linked to progression rate, so this test to me is measuring things that if they are not showing normal, gives you something to work towards trying to correct.

        Also, there are some pALS that have healed and there is a conference coming up in October where they will discuss their strategies, https://healingalsconference.org/

        • Jane says:

          Well all of your comment was well over my head but the others and their frustration hit home. I feel people with ALS are just being bounced around. i want to know where all the money being raised is going. Certainly not for trials etc. Guess for administration. Why are there no homeopathic doctors out there helping to guide patients as to what to do in that choice of treating themselves. Lots of blogs etc about the so called 35 that healed themselves, conference this Oct yada yada yada but no one actually has a plan to share that is specific. Some documentary taking sinc 2014 and not done yet but is coming is talked about. I think the entire thing is a bunch of hog wash and these people raise money for themselves not for any patients.

  8. Dedra says:

    I had a muscle biopsy years ago I was diagnosed with myasthenia gravis now my primary doctor wanna say check me for ALS I have thyroid problems and diabetes…

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