Your doctor will ask about your medical history, and do a physical exam to look for the following signs:
A loss of muscle bulk, and muscle weakness, particularly in the arms and legs
Spasticity. The arms or legs resist being moved by someone else.
Abnormal tendon reflexes
The Babinski sign. The toe moves upward when the sole of the foot is stroked.
Difficulty taking a deep breath in and out
Your doctor will also check to see whether the following have been affected:
Your sense of pain, touch, heat
Higher thought processes, such as:
There is no single test result that confirms an ALS diagnosis. Your doctor will diagnose ALS based on the examination, and by excluding other causes of your symptoms.
Electromyography (EMG) tests how electrical signals travel down your nerves to your muscles. This test can be abnormal in ALS.
Because other neurological conditions besides ALS can cause similar symptoms, other types of studies sometimes are done to try to diagnose these other neurological conditions:
Spinal fluid analysis
Magnetic resonance imaging (MRI) scans
A neurologist is usually the physician who diagnoses ALS. A neurologist is an expert in diseases of the nervous system. If your doctor suspects ALS, he or she should refer you to a neurologist for evaluation.