Diagnosing ALS can be difficult. Symptoms vary from person to person and, at least initially, can mimic other diseases. If an individual has symptoms that suggest ALS, a variety of tests may be performed to make an accurate diagnosis. However, there is no “biomarker,” that is, a standard diagnostic test (like a blood test) which indicates ALS. Diagnosis is made based on expert interpretation of combined information from your neurologist’s physical exam findings , an EMG (electromyelography), and a history of progression of symptoms over time. Additional tests such as bloodwork, an MRI, or a lumbar puncture (“spinal tap”) may be necessary to rule out other possible illnesses.

First, the doctor will ask about medical and family history and will perform a physical exam.  She or he will ask questions about daily functioning, problems with speech, swallowing, or breathing. The doctor will examine the patient, checking for strength, weakness, and sensation in various parts of the body, and check for joint reflexes with a reflex hammer. Blood tests, an EMG, and any other required tests would be ordered at this point if not done already. Some, especially the EMG, may need to be repeated either once or sequentially over time, in combination with further physical exams and monitoring of symptoms.

Below are some of the diagnostic tools used to diagnosis or rule out people with ALS.

Blood tests

Urine tests

Lumbar puncture (spinal tap)

Computed Tomography (CT)

Muscle biopsy

Nerve biopsy

Electromyogram (EMG)

Magnetic Resonance imaging (MRI)

Nerve Conduction Velocity (NCV)


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