Amyotrophic Lateral Sclerosis (ALS) - Exams and Tests

Exams and Tests

A diagnosis of amyotrophic lateral sclerosis (ALS) is based on a careful medical history, a physical exam of the nervous system, and tests that show how the nerves and muscles are working.

If your health professional thinks you have ALS, you may be referred to a neurologist for diagnosis and treatment. A medical history and detailed physical exam of the nervous system can usually help the neurologist diagnose your condition. Tests needed to confirm the diagnosis include electromyogram (EMG) and nerve conduction studies. EMG helps measure how well and how quickly the nerves and muscles are functioning. Nerve conduction studies test nerve function.

Depending on your doctor's findings during the nervous system exam and the results of EMG or nerve conduction studies, other tests may be needed to rule out other possible causes of your symptoms. These tests may include a nerve or muscle biopsy (tissue sample), blood tests, or imaging tests, such as a computed tomography (CT) scan or magnetic resonance imaging (MRI).

ALS may be difficult to diagnose, and the diagnosis may not become clear until symptoms have progressed or until additional testing and observation have taken place. If ALS is suspected, evaluation by a specialist who has experience treating and diagnosing ALS may lead to an earlier diagnosis. Although it does not affect the course or outcome of the disease, an early diagnosis may:

• Give you more time to make decisions about the future and take advantage of the time before symptoms become severe.
• Help you avoid inappropriate treatment resulting from an incorrect diagnosis.
• Give you the opportunity to participate in clinical trials of new treatments for ALS.