A neurologist diagnoses ALS. Specifically, a neurologist with experience in neuromuscular diseases is the specialist qualified to confirm the diagnosis, though most people first see a primary care doctor who then makes the referral. The path from early symptoms to a confirmed diagnosis typically takes about 11.5 months, with a range of 7 to 20 months for most patients.
Where the Process Usually Starts
About 91% of people who are eventually diagnosed with ALS first visit their primary care doctor. The symptoms that bring them in vary widely: progressive changes in speech or swallowing, difficulty walking, painless loss of hand function, a foot that drops when stepping, or a head that’s harder to hold upright. Nearly 70% of patients present with one of these “red flag” symptoms that should prompt consideration of ALS in the differential diagnosis.
In practice, though, primary care doctors don’t always think of ALS right away. One study found that only 28% of initial referrals from a primary care doctor went directly to a neurologist. Doctors often referred patients to ear, nose and throat specialists, orthopedic surgeons, or physical therapists based on where the symptom appeared rather than what pattern it might represent. A person with speech changes might see an ENT, while someone with hand weakness might end up in orthopedics. These detours are one reason diagnosis takes so long.
What a Neurologist Looks For
ALS damages two types of nerve cells: upper motor neurons (which run from the brain down through the spinal cord) and lower motor neurons (which connect the spinal cord to muscles). A neurologist’s core task is finding evidence that both types are failing, which is the hallmark of ALS.
The evaluation starts with a detailed physical and neurological exam. The neurologist tests reflexes, muscle strength, muscle tone, and coordination across different body regions. Upper motor neuron damage produces stiff muscles, exaggerated reflexes, and abnormal reflex responses. Lower motor neuron damage causes muscle wasting, weakness, and visible twitching (fasciculations). Finding both patterns in the same patient, especially across multiple body regions, points strongly toward ALS.
The current diagnostic framework, known as the Gold Coast criteria, requires three things: progressive motor impairment after a period of normal function, signs of both upper and lower motor neuron damage in at least one body region, and thorough testing to rule out other conditions that could explain the symptoms. Earlier criteria systems used categories like “possible” or “probable” ALS, but the Gold Coast approach simplified this into a single diagnostic threshold.
Tests Used to Support the Diagnosis
There is no single blood test or scan that confirms ALS. Instead, neurologists rely on a combination of tests, most of which are designed to rule out other conditions and gather supporting evidence.
Electromyography (EMG) and nerve conduction studies are the most important diagnostic tests. During EMG, a thin needle is inserted into muscles to record their electrical activity. In ALS, the test reveals patterns consistent with lower motor neuron damage. Nerve conduction studies measure how well electrical signals travel along nerves. In ALS, sensory nerves remain normal because the disease spares sensory pathways. This distinction helps separate ALS from conditions like peripheral neuropathy, where sensory nerves are affected. The combination also helps rule out multifocal motor neuropathy, a treatable condition that can look like ALS but shows characteristic “conduction blocks” on nerve testing that shouldn’t appear in ALS.
MRI of the brain and spinal cord is routinely performed, primarily to exclude other explanations for the symptoms: spinal cord compression, tumors, multiple sclerosis, or syringomyelia (a fluid-filled cavity in the spinal cord). MRI can also show changes along the motor pathways in ALS patients, appearing as bright signals on certain scan sequences, but these findings alone aren’t enough to make the diagnosis.
Blood and urine tests check for thyroid problems, infections, heavy metal exposure, and other metabolic conditions. A lumbar puncture (spinal tap) may also be performed. All of these are about exclusion rather than confirmation.
Conditions That Must Be Ruled Out
The list of diseases that can mimic ALS is long, though most are uncommon. The ones neurologists most actively consider include multifocal motor neuropathy, Kennedy’s disease (a genetic condition causing slowly progressive weakness in men), various forms of spinal muscular atrophy, multiple sclerosis, myasthenia gravis, and cervical spinal stenosis compressing the spinal cord. Less common mimics include post-polio syndrome, lead or mercury poisoning, and certain inflammatory muscle diseases.
This extensive process of elimination is one reason the diagnosis takes months rather than days. Each potential mimic may require its own specific test, and neurologists often need to observe a patient over time to confirm that symptoms are truly progressive.
Why Diagnosis Takes Nearly a Year
The median time from first symptoms to confirmed ALS diagnosis is 11.5 months. Some patients receive a diagnosis in 7 months, others wait 20 months or longer. Several factors contribute to this delay. Early ALS symptoms are subtle and overlap with many common conditions. A twitching muscle, mild hand clumsiness, or slight slurring of words can have dozens of benign explanations. The disease also needs time to declare itself: neurologists may need repeated evaluations weeks or months apart to document that weakness is spreading and worsening, which is a core requirement of the diagnostic criteria.
Referral patterns add to the delay. When a primary care doctor sends a patient to an orthopedic surgeon for what turns out to be ALS-related hand weakness, that visit and any subsequent imaging or treatment adds weeks or months before the patient reaches a neurologist.
The Role of Specialized ALS Centers
For a condition this complex, seeing a neurologist who regularly manages ALS makes a meaningful difference. The ALS Association certifies treatment centers across the United States that meet specific standards of care. These Certified Treatment Centers of Excellence use a multidisciplinary model, assembling a team that typically includes a neurologist, physical therapist, occupational therapist, respiratory therapist, nurse, dietitian, speech language pathologist, social worker, and mental health professional. Patients can see all of these specialists in a single visit.
If you or someone you know has received a possible ALS diagnosis, or if symptoms are progressing and no clear explanation has been found, seeking evaluation at one of these specialized centers can speed the diagnostic process and connect patients with a team experienced in both diagnosing and managing the disease. Many neurologists will proactively refer patients to these centers once ALS enters the differential diagnosis.
Emerging Diagnostic Tools
One development worth knowing about is a blood-based biomarker called neurofilament light chain (NfL). When nerve cells are damaged, they release this protein into the bloodstream, and elevated levels can support a diagnosis of ALS. NfL is already used at some specialized centers and in research settings, and it played a notable role in the FDA’s 2023 approval of a treatment for a specific genetic form of ALS. However, no FDA-cleared test exists for routine clinical use yet. The technology requires highly sensitive laboratory equipment that most hospitals don’t have, and elevated NfL isn’t specific to ALS since it rises in many neurological conditions. For now, it’s a supplementary tool rather than a standalone diagnostic test.