Understanding ALS (Lou Gehrig’s Disease) and Why It May be Misdiagnosed

Amyotrophic Lateral Sclerosis (ALS), commonly known as Lou Gehrig’s disease, is a motor neuron disease. It involves progressive loss of nerve signals to the muscles, leading to a lack of muscle control by the brain. However, ALS symptoms are similar to certain other diseases, which can lead to misdiagnosis of ALS.

During the month of May, which is ALS Awareness Month, let’s take a look at some of the signs and symptoms of the disease and how it could lead to the misdiagnosis of ALS.


About 5,600 individuals are diagnosed with ALS in the U.S. annually—somewhere close to 30,000 may be living with the disease at any time.

  • Patients are typically in the 40-70 age group
  • Men are 20% more likely to be diagnosed with ALS overall, but there is no difference in incidence among older men and women
  • White men and women are twice as likely to develop ALS compared to Black men and women
  • Incidence rate among military veterans is significantly higher than in the general population, which may be associated with traumatic brain injury
    • Evaluation of veterans deployed in post-9/11 conflicts found a much higher rate of ALS (19.7 per 100,000 over 14 years, between 2002-2015) compared to veterans from the Gulf War (5.8 per 100,000 over 10 years)


Typical Symptoms

Loss of nerve cells in the brain and spinal cord that leads to progressive muscle weakness, muscle atrophy, and eventually death, ALS does not have a cure. Typical symptoms include muscle twitching, weak limbs, and slurred speech. Other signs of the disease may include:

  • Difficulty walking or conducting daily activities
  • Tripping and falling
  • Difficulty chewing or swallowing
  • Twitching in shoulders and tongue
  • Cognitive and behavioral changes
    • Difficulty with reasoning, remembering, understanding, and problem solving
    • Anxiety and depression associated with progressive loss of function
  • Dementia

What Will Typically Not Happen With ALS?

Pain is not usually associated with ALS, in the early or late stages. Patients also do not lose control of their bladder or their senses.

Causes and Risk Factors of ALS

About 5%-10% of people inherit ALS—this is known as familial ALS and is caused by genetic mutations. These include mutations in the SOD1, C90RF72, FUS, NEK1, TDP43, and TARDBP genes, among others. The cause among the remaining 90%-95% of patients remains unknown and is classified as sporadic ALS.

Exposure to toxins, infectious agents such as viruses, diet, and behavioral and certain occupational factors may increase  the risk of developing ALS.

How is ALS Diagnosed?

ALS diagnosis is complicated and is a combination of medical examination at regular intervals, assessment of health history, and laboratory testing, which includes imaging. The most important aspect here is to rule out other conditions because ALS symptoms are similar to several other diseases that affect nerve cells and muscle function. The following testing may be recommended for confirming an ALS diagnosis:

  • Imaging
    • Electromyography (EMG): Detects electrical activity of muscle fibers
    • Nerve conduction study (NCS): Measures electrical activity in nerves and muscles
    • Magnetic resonance imaging (MRI): Helps produce detailed images of the brain and spinal cord

Specific abnormalities in EMG and NCS may indicate damage to peripheral nerves (which are outside the brain and spinal cord) or muscle disease, symptoms for which may be similar to ALS. MRI is usually normal in people with ALS. But it can help identify issues that cause similar symptoms, such as a tumor on the spine or a herniated disk.

  • Laboratory tests

Blood and urine samples may also be used to eliminate the possibility of other diseases

Misdiagnosis of ALS

Misdiagnosis works both ways:

  • 10-15% of cases are false positive, which means patients are told they have ALS, but their symptoms end up being due to some other condition
  • Nearly 40% of patients are false-negative, meaning they are diagnosed as having some other condition before ALS is confirmed

Patients with Kennedy’s Disease or Multifocal Motor Neuropathy (MMN) may sometimes be diagnosed as having ALS, since the diseases have similar symptoms. However, unlike ALS or Kennedy’s Disease, MMN is not life-threatening. Listen to one patient’s traumatizing story of being misdiagnosed with ALS and how it impacted his life.

Misdiagnosis essentially means delayed diagnosis of the actual condition and can lead to worse prognosis (patient’s outcome) because the disease would have progressed in the interim. ALS is commonly misdiagnosed as cerebrovascular disease, cervical myelopathy, vertebral disc herniation, radiculopathy, neuropathy, and myasthenia gravis. Misdiagnosed patients may endure surgery or treatment for the wrong diagnosis that can lead to unnecessary harm.

Here are some resources and communities that are dedicated to supporting ALS patients and their caregivers:

  1. ALS Association
  2. Les Turner ALS Foundation
  3. NEALS
  4. I AM ALS
  5. EverythingALS

Additional Resources:

  1. National ALS Registry: https://www.cdc.gov/als/ALSJoinALSRegistry.html 
  2. Find an ALS clinical trial: https://www.clinicaltrials.gov/ct2/results?term=amyotrophic+lateral+sclerosis 
  3. EverythingALS.org is conducting a clinical trial to improve diagnosis of ALS: https://www.everythingals.org/research

Surabhi Dangi-Garimella

Surabhi Dangi-Garimella, Ph.D. is a biologist with academic research experience, who brought her skills and knowledge to the health care communications world. She provides writing and strategic support to non-profit groups via her consultancy, SDG AdvoHealth, LLC.

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