Learn About ALS Diagnosis and Your Options

Understanding ALS: What It Is and How It Develops

Amyotrophic lateral sclerosis, commonly called ALS, is a progressive neurological disease that affects nerve cells responsible for muscle movement. The condition damages motor neurons—specialized nerve cells that send signals from the brain and spinal cord to muscles throughout the body. When these neurons deteriorate, muscles gradually weaken and stop working. Eventually, the muscles needed for breathing, speaking, and swallowing become affected.

ALS affects approximately 5,000 people in the United States each year, with roughly 16,000 people living with the disease at any given time, according to the ALS Association. The disease can develop at any age, though it typically begins between ages 40 and 60. Men are slightly more likely to develop ALS than women, with a ratio of about 1.5 to 1.

The disease progresses in different ways for different people. In some cases, weakness starts in the limbs—the arms or legs. This is called "limb onset" ALS. In other cases, weakness begins in the muscles that control speech and swallowing. This is called "bulbar onset" ALS and represents about 25 percent of cases. A small percentage of people experience weakness in the respiratory muscles first, which affects breathing.

Most people with ALS lose the ability to walk, climb stairs, and use their hands and arms within three to five years of symptom onset. Gradually, the disease affects the diaphragm, which is the large muscle that controls breathing. This means many people eventually need mechanical assistance to breathe. The disease does not typically affect thinking, memory, or personality, though a small percentage of people develop frontotemporal dementia alongside ALS.

Practical takeaway: Recognizing early signs of muscle weakness, especially if it occurs on one side of the body or affects your ability to speak and swallow, can help you seek medical evaluation sooner. Understanding how ALS progresses helps you make informed decisions about your care.

Recognizing Early Symptoms and When to See a Doctor

Early symptoms of ALS can be subtle and may be mistaken for other conditions. Many people experience muscle weakness or twitching months before receiving a diagnosis. The initial symptoms vary widely depending on which motor neurons are affected first. Some common early warning signs include difficulty lifting objects, tripping while walking, slurred speech, difficulty chewing or swallowing, muscle cramps, involuntary muscle twitches, or unusual fatigue in the arms or legs.

Some people notice that one arm or leg becomes weaker than the other. Others may have difficulty with fine motor tasks like buttoning shirts or writing. Speech changes might include a hoarse voice or difficulty articulating words clearly. These symptoms often develop gradually over weeks or months, which is why many people don't immediately recognize them as signs of a serious condition.

It's important to mention that muscle twitches, called fasciculations, are common in ALS but also occur in many benign conditions. Similarly, muscle weakness can result from numerous causes including thyroid problems, vitamin deficiencies, infections, or other neurological conditions. This is why medical evaluation is necessary to determine the actual cause of your symptoms.

You should consider scheduling an appointment with your primary care physician if you experience unexplained muscle weakness, persistent muscle twitching, difficulty with speech or swallowing, or unusual fatigue that lasts more than a few weeks. Your primary care doctor can perform an initial evaluation and, if necessary, refer you to a neurologist. A neurologist is a doctor who specializes in diseases of the nervous system and is best equipped to diagnose ALS. If your symptoms progress quickly or significantly affect your daily functioning, don't delay in seeking medical attention.

Practical takeaway: Keep notes about when symptoms started, which body parts are affected, and how the symptoms have changed over time. Bringing this information to your doctor's appointment will help them better understand your condition and guide the diagnostic process.

The Diagnostic Process: Tests and Evaluations

There is no single test that definitively diagnoses ALS. Instead, doctors use a combination of tests and examinations to identify the disease and rule out other conditions that cause similar symptoms. The diagnostic process may take several weeks or even months, which can be frustrating for patients seeking answers. However, this careful approach helps ensure an accurate diagnosis.

A neurologist will start with a detailed medical history and physical examination. During the exam, the doctor tests muscle strength, reflexes, and coordination. They look for signs of muscle wasting and twitching. The neurologist also performs tests of cognitive function to ensure thinking and memory are intact. They ask about your family history, work history, and any exposures to environmental toxins, since some research suggests these factors may play a role in ALS development.

Electromyography, or EMG, is one of the most important diagnostic tests for ALS. During this test, a thin needle is inserted into muscles to measure electrical activity. Healthy muscles produce a specific pattern of electrical signals, while muscles affected by ALS show a different pattern. The test can be uncomfortable but is not dangerous. Nerve conduction studies often accompany EMG. These tests measure how quickly electrical signals travel along nerves and can help determine whether nerve damage is present.

Doctors typically order blood tests and imaging studies like MRI scans to rule out other conditions. Blood tests can identify infections, metabolic problems, or autoimmune disorders that might cause similar symptoms. MRI scans create detailed images of the brain and spinal cord to check for tumors, herniated disks, or other structural problems. Lumbar puncture, or spinal tap, may be performed in some cases to analyze cerebrospinal fluid. This test helps rule out infections or other diseases affecting the nervous system.

Some medical centers use advanced imaging techniques like PET scans or specialized MRI sequences to look for patterns typical of ALS. Genetic testing may be recommended if you have a family history of ALS or related conditions, since about five to ten percent of ALS cases are inherited. The diagnostic criteria were updated in 2015 to help neurologists identify ALS more quickly and accurately, though diagnosis still requires careful evaluation.

Practical takeaway: Write down questions to ask your neurologist about test results and what they mean. Understanding each test and why it's being performed helps you participate more actively in your care and better understand your diagnosis.

Types of ALS and Prognosis Information

ALS exists in several forms, and understanding which type you have can help you anticipate how the disease might progress. The most common form is sporadic ALS, which accounts for about 90 percent of cases. This type occurs randomly with no family history of the disease. Researchers still don't fully understand what causes sporadic ALS, though genetics and environmental factors likely both play roles.

Familial ALS, inherited in families, accounts for approximately ten percent of cases. People with familial ALS have a 50 percent chance of inheriting the disease if one parent carries the gene. Several genes have been identified as causing familial ALS, including SOD1, FUS, and C9orf72. Genetic counseling can help families understand inheritance patterns and what testing options may be available.

Primary lateral sclerosis, or PLS, is a rare variant of ALS that progresses more slowly. People with PLS typically experience only upper motor neuron symptoms, meaning weakness in the upper body and limbs. Lower motor neuron symptoms, like muscle wasting and twitching, are absent or minimal. PLS can progress for many years before becoming more serious.

Progressive muscular atrophy, or PMA, is another rare variant involving primarily lower motor neurons. People with PMA experience muscle wasting and weakness but may not develop the upper motor neuron symptoms typical of classical ALS. This form also tends to progress more slowly than typical ALS.

Prognosis refers to the likely course of the disease. For ALS, prognosis is individual and unpredictable. About one-third of people with ALS live five years or longer after diagnosis, while some people live ten years or more. Survival depends on factors including age at onset, which body part is affected first, how quickly the disease progresses in the first year after diagnosis, and overall general health. People who maintain good nutrition and respiratory function tend to survive longer. The drug riluzole has been shown to extend survival by a few months on average, and a newer drug, edaravone, may slow disease progression in some people.

Practical takeaway: