How is MND diagnosed?
If your general practitioner (GP) suspects a neurological problem, you will be referred to a neurologist who does the diagnosis. To improve timely referrals MND NZ has a Red Flag MND Diagnosis tool [EK8] to help GPs.
If your neurologist believes there is cause for concern you may be sent for a series of diagnostic tests, which may include the following:
This test is sometimes called the needle test, because fine needles are used to record the naturally occurring nerve impulses within certain muscles. Muscles that have lost their nerve supply can be detected because their electrical activity is different from normal healthy muscles. Recordings are usually taken from each limb (usually on one side only), paraspinal (back), and the bulbar (throat) muscles. The EMG can be shown as abnormal even if that particular muscle is as yet unaffected.
Nerve Conduction Test
An electrical impulse is applied through a small pad on the skin, which measures the speed at which your nerves carry electrical signals. This test is usually carried out at the same time as the EMG.
Transcranial Magnetic Stimulation (TMS)
This procedure is designed to measure the activity of the upper motor neurones; its findings can help in the diagnostic process. It is not routinely performed in New Zealand, but is sometimes performed as part of research in MND.
Magnetic Resonance Imagery (MRI) scans
This involves lying flat in an MRI scanning machine. An MRI scan will not diagnose MND, because the damage caused by MND does not show up on this scan. It is a tool for eliminating other conditions that can mimic symptoms of MND.
Like MRI, blood tests cannot diagnose MND, but are useful in some cases to exclude other conditions that may resemble MND. For example, a rise in levels of creatine kinase (released when muscle breaks down) can occasionally be found in the blood of people with MND, but it is not specific for MND and is mostly performed to exclude muscle diseases that can resemble MND.
Lung Function Tests
These tests are done to assess the strength of the breathing muscles and may be used to determine whether breathlessness is due to muscle weakness, or some other reason (e.g. asthma or emphysema). They are often followed with repeated measurements over time.
This is not an exhaustive list; there are several other tests your neurologist may order, and you should feel free to enquire as to what each test is for when you see him/her.