There is no single test used to make an ALS diagnosis. An ALS diagnosis is typically based on a person's symptoms, such as spasticity and muscle weakness. Tests used to rule out other diseases before making an accurate ALS diagnosis include magnetic resonance imaging and electromyography. In order for your doctor to make a definitive ALS diagnosis, he or she will also need your full medical history and will conduct a neurological exam.
Although there is no test that can provide a definitive ALS diagnosis, the presence of upper and lower motor neuron signs in a single limb is strongly suggestive. However, an ALS diagnosis is based primarily on the signs and symptoms that appear and on a series of tests that rule out other diseases.
In order for your doctor to make an ALS diagnosis, he or she will need to obtain your full medical history and conduct a neurological examination. The examination will be performed at regular intervals to assess whether possible symptoms of ALS are getting progressively worse.
Possible symptoms of ALS include:
- Muscle weakness
- Atrophy of muscles
Appropriate tests must be conducted to exclude the possibility of other conditions, because symptoms of ALS can be similar to those of other, more treatable diseases or disorders.
Tests that are used to make an ALS diagnosis include:
- Electromyography (EMG)
- Nerve conduction velocity (NCV)
- Magnetic resonance imaging (MRI)
- Blood and urine tests
- Muscle biopsy.
Electromyography (EMG) is a test that uses a special recording technique that detects electrical activity in muscles. Certain EMG findings can support the diagnosis of ALS.