Diagnosis
ALS is not diagnosed by one single test. Diagnosis is based on the clinical picture, neurological examination and tests that help exclude other likely causes.
How diagnosis is made
- Detailed neurological examination.
- Electromyography (EMG) and nerve conduction studies.
- MRI when needed to exclude spinal cord, brain or structural causes.
- Blood tests to rule out metabolic, inflammatory or deficiency-related conditions.
- Genetic testing when indicated.
- Lumbar puncture in selected cases.
Diagnostic criteria
El Escorial
Older clinical criteria that classify diagnostic certainty based on upper and lower motor neuron signs in different body regions.
Awaji
Criteria that give greater weight to EMG findings, especially fasciculation potentials in the right clinical context.
Gold Coast
Simpler modern criteria focusing on progressive motor impairment plus upper/lower motor neuron evidence and exclusion of other causes.
Conditions that may resemble ALS
Multifocal motor neuropathy (MMN)
Can cause progressive limb weakness and may respond to immunoglobulin therapy.
Cervical myelopathy
Compression of the spinal cord in the neck can cause weakness, brisk reflexes and gait problems.
Myasthenia gravis
Typically causes fatigable weakness and may affect eyes, swallowing or speech.
Neuroborreliosis
Lyme disease can affect the nervous system in some cases and should be considered when the clinical context supports it.
Vitamin B12 deficiency
May cause sensory symptoms, weakness and gait problems.
Inclusion body myositis
A slowly progressive muscle disease that can sometimes mimic motor neuron disease.