The most common symptoms of ALS, also known as Lou Gehrig's disease, include weakness in the ankles, legs or feet, slurring of speech, muscle cramps or twitching, and difficulty walking, according to Mayo Clinic. Patients may also have hand weakness, posture and difficulty with normal daily activities.
Diagnosing ALS can be difficult during the early stages because symptoms mirror muscle, neurological and spinal cord diseases, according to Mayo Clinic. To diagnose ALS, neurologists discuss the symptoms with patients and evaluate their family histories of neuromuscular diseases. A complete physical exam is conducted to determine any areas of muscle weakness.
Additional testing to diagnose ALS often includes blood tests to check for the enzyme creatine kinase, which may be leaking from damaged muscles, and an examination of the cerebrospinal fluid surrounding the brain, explains Mayo Clinic. An electromyogram, a test to measure electrical signals in the muscles, may be used to monitor electrical activity in the muscles to determine any weakness or signs of malfunctioning motor nerves.
In some cases, physicians perform a muscle biopsy to uncover muscle disorders, such as muscular dystrophy, which has similar symptoms to ALS, as Mayo Clinic explains. A nerve conduction study may also be performed to measure electrical nerve impulses.