Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s disease, is a progressive neurodegenerative disease that affects nerve cells in the brain and spinal cord. ALS causes loss of muscle control, eventually leading to paralysis and death usually within 2-5 years from symptom onset. There is currently no cure for ALS.
ALS is diagnosed based on a person’s symptoms, a series of tests, and by ruling out other possible causes. A neurologist, a doctor who specializes in conditions affecting the nervous system, plays a key role in diagnosing ALS. This article provides an overview of how a neurologist makes an ALS diagnosis.
What are the symptoms of ALS?
The first symptoms of ALS often include:
– Muscle weakness or stiffness in the arms, legs, mouth, or throat
– Difficulty speaking or swallowing
– Twitching and cramping of muscles
– Tripping or falling
These initial symptoms often start in one region like the arm or leg, before spreading to other parts of the body as the disease progresses.
Other ALS symptoms include:
– Loss of muscle bulk or weight loss
– Breathing problems
– Cognitive and behavioral changes (less common)
The order and rate at which parts of the body are affected by ALS varies significantly from one person to another.
Who is affected by ALS?
ALS can affect anyone, but certain factors make someone more likely to develop the disease:
– Age: Most people with ALS are between 40 and 70 years old at symptom onset.
– Sex: Slightly more men than women develop ALS.
– Genetics: About 5-10% of cases are inherited. A defect in the C9orf72, SOD1, TARDBP, or FUS genes leads to familial ALS.
– Military veterans: Veterans are approximately twice as likely to develop ALS.
How do neurologists test for ALS?
Neurologists use the following diagnostic tests and exams to determine if someone has ALS:
Physical exam
A neurologist will perform a physical exam, testing muscle strength, reflexes, coordination, and ability to walk. Weak, stiff muscles and overactive reflexes are hallmark signs of ALS.
Electromyography (EMG)
An EMG test evaluates the electrical activity of muscles and nerves. It can detect abnormal electrical discharges in muscles that may signal ALS.
Nerve conduction study
This test measures how well and how fast electrical signals move through a nerve. It can show nerve damage caused by ALS.
MRI
Magnetic resonance imaging (MRI) creates images of the brain and spinal cord to check for other possible conditions.
Muscle or nerve biopsy
Removing a small sample of muscle or nerve tissue for testing can help rule out muscle or nerve diseases that mimic ALS.
Blood and urine tests
Blood counts, electrolytes, thyroid function, and serum protein tests determine whether something else could be causing symptoms.
| Test | Purpose |
|---|---|
| Physical exam | Checks muscle strength, reflexes, coordination, walking |
| Electromyography | Measures muscle and nerve electrical activity |
| Nerve conduction study | Evaluates nerve signal speed and damage |
| MRI | Creates images of the brain and spinal cord |
| Muscle/nerve biopsy | Samples tissue to rule out other diseases |
| Blood and urine tests | Checks for other potential causes |
Tracking progression
ALS symptoms typically worsen progressively over time. Neurologists may repeat certain tests like an EMG periodically to track how quickly the disease is advancing.
Making the ALS diagnosis
Neurologists diagnose ALS based on:
– Signs and symptoms of muscle weakness and atrophy that cannot be explained by other conditions
– Results of diagnostic testing that point to motor neuron degeneration
– Progression of symptoms over time that match the typical ALS disease course
There is no single conclusive test that can diagnose ALS. The neurologist pieces together results from the entire clinical evaluation to definitively diagnose ALS. This ensures ALS is differentiated from ALS-like disorders that may require alternate treatments.
Some factors neurologists consider when making an ALS diagnosis include:
Rate of progression
– ALS gets progressively worse over a period of just a few years. Rapid progression of muscle weakness and wasting is typical in ALS.
Parts of the body affected
– ALS starts in one area like an arm or leg before spreading. Weakness that starts simultaneously in multiple areas raises suspicion for mimic disorders.
Upper and lower motor neuron damage
– ALS damages both upper and lower motor neurons. Neurologists look for combined symptoms like muscle twitching from lower motor neuron damage and stiffness/spasticity from upper motor neuron damage.
No sensory, cognitive, or bladder symptoms
– ALS spares sensation, thinking, and bladder control. Presence of these symptoms indicates an alternate diagnosis.
EMG results
– EMG shows the muscle electrical instability typical of ALS damage. Normal EMG suggests a different condition.
Progression despite treatment
– ALS continues to advance even with treatment. Stability argues against the diagnosis.
Getting a second opinion
Due to the serious implications of an ALS diagnosis, neurologists often recommend a person with suspected ALS get a second opinion from an ALS specialist. ALS is a complex disease and there are many ALS mimics. Having the diagnosis confirmed by more than one highly experienced neurologist helps ensure diagnostic accuracy.
Major clinics like the Mayo Clinic have multidisciplinary ALS specialty teams who see patients for second opinions. Local chapters of the ALS Association can provide referrals to ALS experts as well.
Coping with an ALS diagnosis
Being diagnosed with ALS is a devastating blow. At the same time, receiving a definitive diagnosis often comes as a relief after months or even years of uncertainty and searching for answers.
While ALS currently cannot be cured, much can be done to treat symptoms and improve quality of life. Early intervention with medications, therapies, and assistive equipment makes a significant difference. Most people with ALS live 2 to 5 years after diagnosis.
Neurologists and multidisciplinary ALS clinic teams work to provide comprehensive support to patients and families after diagnosis. Counseling, physical therapy, speech therapy, medications, nutritional advice, equipment prescriptions, and home care assistance can help people maintain independence and fulfillment despite disability from ALS.
Ongoing clinical trials offer hope that effective treatments and ultimately a cure for ALS will be discovered. Getting involved in research studies gives patients an opportunity to play an active role in defeating this disease.
Conclusion
ALS is a clinically complex disease. Diagnosing ALS requires extensive testing, tracking of symptom progression over time, and differentiating ALS from mimic disorders by an experienced neurologist. While challenging to diagnose, recent advances are improving diagnostic accuracy and speed.
Despite being an incurable disease, much can be done to assist patients in maintaining quality of life after an ALS diagnosis. A team-based approach focusing on symptom management and support services provides the best outcome. While emotionally difficult, receiving a definitive ALS diagnosis as early as possible is crucial in order to initiate optimal treatment. Ongoing research strives to find meaningful treatments until a true cure can be discovered.