How is ALS diagnosed?
In addition to a complete medical history and physical examination, diagnostic procedures for ALS may include:

• laboratory tests - including blood and urine studies and thyroid functioning tests
• muscle and/or nerve biopsy
• cerebral spinal fluid analysis (spinal tap) -- a procedure used to make an evaluation or diagnosis by examining the fluid withdrawn from the spinal column.
• X-rays
• magnetic resonance imaging (MRI) - a way to image soft tissues that's noninvasive and that doesn't involve X-rays. MRI produces a sharp, two-dimensional view of the brain and spinal cord.
• electrodiagnostic tests (i.e., electromyography (EMG) and nerve conduction velocity, or NCV) - studies that evaluate and diagnose disorders of the muscles and motor neurons. Electrodes are inserted into the muscle, or placed on the skin overlying a muscle or muscle group, and electrical activity and muscle response are recorded.