How MND is diagnosed
The most important component in the diagnosis of MND is taking a history from a patient and conducting a thorough neurological examination. There is no single test to diagnose motor neurone disease and every patient is different. The medical team decides which tests should be performed on a case by case basis. Tests are performed to look for supportive features of motor neurone disease and to look for other possible causes of a patient's symptoms (See 'Are there other conditions that can mimic MND?').
Tests that may be requested by the medical team to help diagnose MND include:
There is no blood test to diagnose MND. However, blood tests might be performed to look for evidence of damage to the muscle (called CK, or creatine kinase), to look for causes of inflammation in the spinal cord (such as vitamin B12 levels) or to look for supportive evidence of damage to the motor nerves (such as anti-ganglioside antibodies). The appropriateness of each test is determined on a patient by patient basis and as all patients are different all the tests may not be performed on every patient.
Nerve conduction studies (NCS) and electromyography (EMG)
It is very likely that the medical team will request this test for all patients being investigated for motor neurone disease. A specialist doctor called a neurophysiologist performs the nerve conduction and EMG tests. They will decide which nerves and muscles to test on a case by case basis and then analyse the results to establish whether or not the findings support a diagnosis of MND or are suggestive of another condition.
Sometimes a patient may have to undergo nerve conduction studies & EMG on more than one occasion so that any changes over time can be identified.
Nerve conduction studies test the peripheral nerves which are made up of lower motor neurones and sensory nerves. It involves stimulating the peripheral nerves to generate an electric signal which can be recorded. The degree and pattern of stimulation of the peripheral nerves can be analysed to identify changes consistent with MND or those that might suggest a different cause.
Electromyography, or EMG, involves inserting small needles – like acupuncture needles – into muscles in different parts of the body. This is not dangerous and very rarely painful. Analysis of the electrical activity and activation of the muscles can identify changes consistent with MND or those that might suggest a different cause.
Magnetic Resonance Scanning (MRI)
The medical team may decide to perform an MRI scan based upon a patient's history and examination. MRI scans are performed in the radiology department and the images are reviewed by a specialist doctor called a radiologist who reports the scan. The MRI scan cannot diagnose motor neurone disease but can look for evidence of other causes of a patient's symptoms such as damage to the spinal cord in the neck (upper motor neurone) and the nerves that leave the neck to supply the muscles (lower motor neurone) caused by 'wear and tear' changes. Sometimes, in addition to performing an MRI scan of the neck (medically known as the 'cervical spine') the medical team might perform a MRI scan of the brain or other parts of the spine (to look for evidence of inflammation, for example).This is a painless non invasive test. If you think you might have difficulty in lying still in a small confined space let your doctor know so that you can be given medicines to relax prior to the test.
The medical team may decide to perform a lumbar puncture based upon a patient's history and examination. A lumbar puncture cannot diagnose motor neurone disease but can look for evidence of other causes of a patient's symptoms (such as inflammation in the spinal cord and brain).
A lumbar puncture involves sampling the cerebrospinal fluid (CSF) that surrounds the brain and spinal cord acting as a shock absorber. The procedure is usually performed by asking a patient to lie on their left side. The lower back is cleaned and the area is made numb by using a local anaesthetic. A needle is then inserted into the space between the bones of the lower spine (below the end of the spinal cord) to obtain the CSF. This is sent for analysis. A blood test is required at the same time so the CSF and blood can be compared.