Diagnosing ALS can be difficult as there is no single test or examination that can conclusively say whether or not a person has ALS. The El Escorial Criteria are commonly used as an aid when making an ALS diagnosis and require the following:

1.) Evidence of lower motor neuron (LMN) degeneration by clinical, electrophysiological or neuropathologic examination.

2.) Evidence of upper motor neuron (UMN) degeneration by clinical examination.

3.) Progressive spread of symptoms or signs within a region or to other regions, as determined by history or examination.

While these criteria can help a medical professional come to a diagnosis of ALS, they do have their limits in that the criteria ignore family history and genetic data and do not take into account that there are specific clinical phenotypes, subtypes of ALS, that may have distinct prognoses and may at first look like other diseases. For this reason, a variety of examinations and procedures may be necessary to rule out other diseases and neurological disorders that have similar symptoms to ALS. Some of the procedures that can help eliminate other disorders include genetic testing, electromyography and nerve conduction studies, muscle biopsy, magnetic resonance imaging (MRI), blood and urine tests and spinal taps. While the combination of some or all of these tests can help to make an ALS diagnosis clearer, researchers are attempting to develop a singular tool that could be used to diagnose ALS, thus allowing them to expedite the diagnostic process. 

Since there are multiple steps that need to be taken before an ALS diagnosis can be given, the process can take up to 12 to 14 months. During this diagnostic period, a person may receive a diagnosis of suspected, possible, probable or definite ALS. These classifications are based upon what areas of the body are affected by ALS symptoms, as determined during clinical examination. A suspected ALS diagnosis is given when only lower motor neuron loss is detected in multiple regions of the body. Possible ALS diagnosis is given when the loss of both upper and lower motor neurons is detected in one region of the body. When the loss of both upper and lower motor neurons is detected in two regions of the body then a probable ALS diagnosis is usually given. Once the loss of both upper and lower motor neurons is seen in three or more regions of the body a definite ALS diagnosis is given.

Only a licensed medical professional can diagnose ALS. If you receive an ALS diagnosis, it’s important to talk to your doctor and stay informed to determine what your options are.

For more information on ALS, please visit https://www.als.net/what-is-als/.

For information on ALS resources, visit https://www.als.net/resources/.