There are many different neurological tests and the ones your neurologist chooses to perform will depend, in part, on the symptoms that you present with. Here are some of the more common ones.
Romberg’s sign: This is a test for ataxia (incoordination or clumsiness of movement that is not the result of muscular weakness) and involves standing with your feet together with your eyes closed. Ataxics have great problems standing still under these conditions.
Gait and coordination: The neurologist evaluates ataxia in various parts of the body by observing the patient walking normally, walking heel-to-toe and finger-to-nose tests. The neurologist will also be looking for intention tremor (shaking when performing small motor movements) as well as ataxia in this last test.
Heel/Shin test: This is a test for ataxia and cerebellar dysfunction. You have to bring the ball of your heel onto the knee of your other leg and then move it down the shin.
L’Hermittes sign: This is a test for lesions on the spinal cord in the neck. The neurologist will ask you to lower your head towards your chest. A positive L’Hermittes will generate buzzing, tingling or electrical shock sensations in one or more parts of the body.
Optic Neuritis: This is a condition of the eye caused by inflammation and demyelination of the Optic Nerve and is perhaps the most commonly presenting symptom in MS. The tests involve the ubiquitous reading of letters from a board and a test for colour vision using an “Ishihara” colour chart. An examination with an opthalmoscope will reveal pallor of the optic nerve in old optic neurites.
Hearing Loss: This is done by lightly clicking the fingers next to each ear and asking the patient which ear the click was done next to.
Muscle Strength: This involves resisting the neurologist with various muscle groups. Differences in strength between left and right sides are easier to evaluate than symmetrical loss unless the weakness is severe.
Reflexes: This is done with both ends of the hammer. The reflexes can be normal, brisk, i.e. too easily evoked, or non-existent.
Babinski’s sign: A test for signs of disease process in the motor neurons of the pyramidal tract. The test involves drawing a semi-sharp object along the bottom of the foot. The normal response in adults and children is for the toes to reflex downwards (flexor response). In babies and people with neurological problems of the corticospinal tract, the big toe moves upwards (extensor response).
Chaddock’s Sign: Similar to Babinsky’s but testing for lesions in the corticospinal tract. The neurologist touches the skin at the outside of the ankle. A positive response in upwards fanning of the big toe just like in Babinski’s test.
Hoffman’s sign: This is also similar to Babinski’s but involves the hands rather than the feet. Again it tests for problems in the corticospinal tract. The test involves tapping the nail on the third or forth finger. A positive response is seen in flexion of terminal phalanx of thumb.
Doll’s Eye Sign: The neurologist is looking for dissociation between movement of the eyes and of the head. A positive response is when the eyes moves up and head moves down.
Sensory: This is done with tuning forks and pins and tests the level of sensory perception in certain parts of your body.
“Can you get a definite diagnosis from the neurological examination?”
It is very rare to get a definite diagnosis at this stage. Certain signs and symptoms are more indicative of multiple sclerosis than others, but, assuming that you do have the disease, the most definitive dx you will get will be “probable MS”. You are much more likely to get a dx of “possible MS”.
The neurologist will probably book you in for several tests including MRI scans, spinal taps and evoked potential tests.
It is important to note that whatever the results of these tests or the neurological exam, it is not possible to diagnose definite MS from a single episode. There are a number of demyelinating conditions of unknown aetiology which are self-limiting and strike only once. In order to diagnose MS, there must be at least two episodes separated by at least one month and the location of the lesions must be in a least two distinct sites in the central nervous system. This means that the PwMS will, by definition, have to wait at least the period of time that separate the first two relapses that cause clinical symptoms. This could be as little as one month but is more likely to be several months or even years. Often people want a definite diagnosis, but they certainly don’t want to have to have another relapse to prove it. Catch-22.
Neurologists used to use a checklist called the Schumacher criteria to confirm a diagnosis of multiple sclerosis. Though these criteria are now largely outdated, an MS diagnosis remains a clinical one and they still form the basis for later revisions. They are also worth looking at because they are the simplest statement of what MS is, clinically. The Schumacher criteria are:
- Neurological examination reveals objective abnormalities of CNS function.
- History indicates involvement of two or more parts of CNS.
- CNS disease predominately reflects white matter involvement.
- Involvement of CNS follows one of two patterns:
- Two or more episodes, each lasting at least 24 hours and at least one month apart.
- Slow or stepwise progression of signs and symptoms over at least 6 months.
- Patient aged 10 to 50 years old at onset.
- Signs and symptoms cannot be better explained by other disease process.
From Schumacher et al, 1965
The Poser criteria have updated the Schumacher criteria in recognition of the diagnostic benefits of laboratory data. They have not changed the fact that MS is still essentially a clinical diagnosis and are themselves about to be replaced by new criteria that acknowledge the importance of Magnetic Resonance Imaging (MRI). The Poser criteria are:
- Clinically definite MS
- 2 attacks and clinical evidence of 2 separate lesions
- 2 attacks, clinical evidence of one and paraclinical evidence of another separate lesion
- Laboratory supported Definite MS
- 2 attacks, either clinical or paraclinical evidence of 1 lesion, and cerebrospinal fluid (CSF) immunological abnormalities
- 1 attack, clinical evidence of 2 separate lesions & CSF abnormalities- 1 attack, clinical evidence of 1 and paraclinical evidence of another separate lesion, and CSF abnormalities
- Clinically probable MS
- 2 attacks and clinical evidence of 1 lesion
- 1 attack and clinical evidence of 2 separate lesions
- 1 attack, clinical evidence of 1 lesion, and paraclinical evidence of another separate lesion
- Laboratory supported probable MS
- 2 attacks and CSF abnormalities
From Poser, 1983
Still more recently, 4th May 2001, an international panel in collaboration with the NMSS of America has recommended revising the diagnostic criteria for multiple sclerosis.
The new proposed diagnostic criteria are:
| Clinical Presentation |
Additional Data Needed |
- 2 or more attacks
- 2 or more objective clinical lesions
|
None; clinical evidence will suffice
(additional evidence desirable but must be consistent with MS) |
- 2 or more attacks
- 1 objective clinical lesion
|
Dissemination in space, demonstrated by
- MRI
- or a positive CSF and 2 or more MRI lesions consistent with MS
- or further clinical attack involving different site
|
- 1 attack
- 2 or more objective clinical lesions
|
Dissemination in time, demonstrated by
- MRI
- or second clinical attack
|
- 1 attack
- 1 objective clinical lesion
(monosymptomatic presentation) |
Dissemination in space by demonstrated by
- MRI
- or positive CSF and 2 or more MRI lesions consistent with MS
and
Dissemination in time demonstrated by
- MRI
- or second clinical attack
|
Insidious neurological progression
suggestive of MS
(primary progressive MS 2 ) |
Positive CSF
and
Dissemination in space demonstrated by
- MRI evidence of 9 or more T2 brain lesions
- or 2 or more spinal cord lesions
- or 4-8 brain and 1 spinal cord lesion
- or positive VEP with 4-8 MRI lesions
- or positive VEP with <4 brain lesions plus 1 spinal cord lesion
and
Dissemination in time demonstrated by
- MRI
- or continued progression for 1 year
|
“So, tell me more about the other tests.”
Magnetic Resonance Imaging (MRI)
Along with the neurological exam, this is by far and away the most useful and definitive of diagnostic tools. MRI is a branch of Nuclear Magnetic Resonance (NMR) a procedure that involves detecting how molecules spin in powerful magnetic fields. MRI was first used in medicine in 1977 and, though expensive, it is unparalleled at detecting changes and abnormalities inside soft bodily tissue. Water molecules, which are present in all soft tissue, carry a small electromagnetic polarity and, as a result, act like minuscule magnets. MRI scanners exert enormously powerful magnetic fields around the patient who lies in a tube in the middle of the scanner. This causes all the water molecules to wobble and this is detected and imaged on a computer, from which it can be printed onto a negative.
MRI is completely harmless provided that you do not have any magnetic metals around your person during the scan. For more details on MRI and safety procedures, follow this link: Magnetic Resonance Imaging.
MRI scans give detailed high resolution images of cross sections of the brain and to a lesser extent, the spinal cord. Multiple Sclerosis lesions show up as paler areas on those images. From an MRI, the neurologist can not only identify that there have been probable demyelination events but can also see where those lesions are and use them to explain both present and potential signs and symptoms.
Surprisingly perhaps, and despite its accuracy, an MRI scan alone cannot be used to make a definite diagnosis of MS. Clinical symptoms are usually necessary and, because there are a number of other demyelinating conditions, these must be ruled out. As already mentioned, the clinician will also want evidence that there has been at least two identified demyelinating episodes separated by at least one month in at least two different locations in the CNS.
Nor do MRI scans always pick up MS lesions. There is evidence that some older lesions remyelinate sufficiently to be undetectable with MRI scans. Having said this, the vast majority of people with a definite dx of MS will show evidence of disease activity on MRI scans.
Spinal Tap
A spinal tap (also known as a lumbar puncture) is a procedure whereby a sample of cerebrospinal fluid (CSF) is taken from close to the spinal cord. At the same time a blood sample is taken usually from the arm and a quantity of blood serum is isolated. Both of these samples are then processed using a technique called electrophoresis. A positive spinal tap will produce oligoclonal bands in the CSF but not in the blood serum. These bands indicate a type of immune system activity. Although uncomfortable, the spinal tap itself is often not too painful, whereas in the period following the tap, the patient may experience dizziness, nausea, vomiting and severe headaches, occasionally for as much as a week. There are a few rare but serious side-effects of spinal taps. For more information about spinal taps and how to reduce the possibility of some of the more unpleasant side-effects follow this link: Spinal Tap.
95% of people with a definite diagnosis of MS exhibit oligoclonal bands on a spinal tap. This may sound impressive but so do 90% of people with Sub-Acute Sclerosing Panencephalitis and 100% of people with Herpes Simplex Encephalitis among other conditions. Positive spinal taps are indicative of an immunological response but they are not diagnostic for a particular condition. That 5% of PwMS do not exhibit oligoclonal banding means that spinal taps neither rule-in nor rule-out MS.
The primary purpose of CSF analysis should be to rule out other conditions than multiple sclerosis. Although they can be highly suggestive of MS, they do not, in themselves, provide definitive disgnosis. Indeed, I myself, was given a definite diagnosis based on medical history, clinical examination, MRI and evoked potential tests - I declined to have a spinal tap.
Before MRI, electrophoresis of spinal fluid played a major role in supporting diagnoses and underpinned the Poser criteria. Now, however, these criteria have become overshadowed by MRI and, if an MRI is positive, the new diagnostic criteria (2001)allow for a definitive diagnosis without laboratory support. The old “Laboratory supported Definite MS” has been dispensed with.
However, CSF analysis technology is still advancing and researchers continue to look for definitive molecular markers of MS. Should they find such a marker, spinal taps will reassume their importance. Other researchers are looking into urine and blood for markers and we can hope that they are successful and spinal taps become completely unnecessary to the diagnosis of multiple sclerosis.
Evoked Potential (EP) tests
Evoked Potential tests are procedures for measuring the speed of impulses along neurons. Responses can be measured using EEG readings from electrodes attached to the scalp and occasionally other areas of the skin. Although this may sound like something from Frankenstein, they are in fact completely painless and entirely harmless. Based on input signals to the particular sense being measured, the time taken for that response to register can be accurately measured and compared to normal readings. The results are then analysed on a computer and average speeds recorded.
Demyelinated neurons transmit nerve signals slower than non-demyelinated ones and this can be detected with EP tests. Although they may appear to function perfectly, even remyelinated neurons are slower than normal nerves and so historical lesions can be detected in this way.
There are three main types of evoked potential test:
Visually Evoked Potential (VEP)
This test measures the speed of the optic nerve. The patient has to focus on the centre of a “TV” screen on which there is a black and white chequered pattern. Each square in the pattern alternates between black and white at measured intervals. The patient wears a patch on one eye for a while and then on the other, so that the speed of both optic nerves can be measured.
85-90% of people with definite MS and 58% of people with probable MS will have abnormal VEP test results.
Brainstem Auditory Evoked Response (BAER)
The BAER test measures the speed of impulses along the auditory portion of Cranial Nerve VIII. This nerve arises in the Pons area of the Brainstem and therefore this test may be indicative of lesions in that area. The patient lies down in a darkened room to prevent visual signals from interfering with measurements. A series of clicks and beeps are played back to the patient.
67% of people with definite MS and 41% of people with probable MS will have abnormal BAER test results.
SomatoSensory Evoked Potential (SSEP)
The SSEP test involves strapping an electrical stimulus around an arm or leg. The current is switched on for 5 seconds and electrodes on the back and skull measure the response at particular junctions. The current is very low indeed and completely painless. The speed of various nerves can be measured in this way and the points of slow-down (i.e. demyelinated lesions) approximated to because of the sampling at several places.
77% of people with definite MS and 67% of people with probable MS will have abnormal SSEP test results.
Slow nerve responses in any of these tests are not necessarily indicative of MS but can be used in conjunction with a neurological examination, medical history, an MRI and a spinal tap to deduce some kind of diagnosis.
CT scans
Computed Tomography scans use X-rays to produce images of the brain. CT scanners look a lot like MRI scanners and are also used to produce cross-sectional images of internal parts of the body. However, CT scans detect soft body tissue with far less precision that MRI scans and their use has largely been replaced by them. Since CT scans use X-rays which are potentially very harmful, this is no bad thing. Sadly, MRI scanners are much more expensive than CT scanners and many areas where MS is relatively common do not have access to them.
George
phew I vaguely remember doing some of those test 5yrs ago with the neuro so when I finally get to see some1 again it’ll be interesting to compare previous results good health Samj 