ALS can be very difficult to diagnose. There is no one test or procedure to confirm the diagnosis.

To determine if you have ALS, your doctor will perform an evaluation that includes a physical exam, medical history, lab tests such as blood and urine tests, and imaging tests such as magnetic resonance imaging (MRI) of the brain and spinal cord.

Electromyography (EMG) may be used to test the health of your muscles and the nerves controlling your muscles. This test is very sensitive in detecting lower motor neuron disease.

There are no standard laboratory tests for upper motor neuron disease. But certain signs may be interpreted by your doctor as signs of ALS such as:

  • Babinski's reflex, an unusual flexing of the toes that signals damaged nerve paths
  • Diminished fine motor coordination
  • Muscle cramps, which can be painful, and twitching
  • Spasticity, a specific type of stiffness that causes jerky, hard to control movements

UCSF Health medical specialists have reviewed this information. It is for educational purposes only and is not intended to replace the advice of your doctor or other health care provider. We encourage you to discuss any questions or concerns you may have with your provider.