ALS is very difficult to diagnose — often taking up to a year from when the first symptoms appear until a definitive diagnosis is reached. Why is diagnosing a person with ALS such a challenging and long process? Here are a few reasons that can contribute to the delay:
1. There is no clear cause of ALS.
Because there is no clear cause or trigger for ALS, and in most cases, no specific genes, it is diagnosed by asking disease-related questions and taking a history of the patient’s symptoms. It is very important that a doctor with knowledge of ALS — such as a neurologist or a specialist with experience with ALS — conducts this examination to see the symptoms and clues that need to be observed together to confirm the diagnosis, as well as to rule out other possible conditions.
2. ALS is usually thought of as something else at first.
People with ALS experience a wide variety of symptoms, especially early on in the progression of the disease. One person may experience muscle twitches or weakness and think at first that they just overexerted themselves at the gym, and another may experience slurred speech and think they may have had a stroke. The way symptoms present can lead to many areas or specialists before being referred to a neurologist. It’s typically only when more symptoms appear that ALS is thought of as a possibility.
3. There is no specific diagnostic test for ALS.
An ALS diagnosis is a process of exclusion, which means that doctors have to test for other possible explanations to rule out other diagnoses. A comprehensive diagnostic workup includes most, if not all, of these procedures:
- blood and urine studies
- x-rays, including MRI
- electrodiagnostic tests including electomyography (EMG) and nerve conduction velocity (NCV)
- spinal tap
- muscle and/or nerve biopsy
- myelogram of cervical spine
When physical and laboratory examinations indicate that a person has weakness caused by the loss of motor neurons, worsening over time and spreading to different parts of the body, along with test results showing a decrease in muscle and nerve function, a diagnosis can be confirmed. It is always important to get a second opinion, especially when given an ALS diagnosis, because of the wide variety of symptoms and different tests that can be done.
Currently, promising research is being done to diagnose ALS earlier and faster with the help of biomarkers. Biomarkers are biological measures that help identify the presence or rate of progression of a disease or the effectiveness of a therapeutic intervention. Biomarkers can be molecules derived from bodily fluids (blood and cerebrospinal fluid), an image of the brain or spinal cord, or a measure of the ability of a nerve or muscle to process electrical signals. This research could identify a test that could be done to find an ALS diagnosis earlier in someone’s disease progression, enabling them to start drugs and therapy faster.
For more information on biomarker research, see The ALS Association’s Research page.