Timothy C. Hain, MD• Page last modified: January 6, 2019
While many persons with dizziness are very anxious about having MS, practically it is very uncommon to diagnose MS in a person with vertigo or unsteadiness. The reason for this is that MS is an uncommon disease, far less common than inner ear conditions such as BPPV, or common neurological disorders such as migraine.
On the other hand, MS can sometimes be a devastating neurological illness, and treatments are gradually becoming available. Thus, thought is that although MS is uncommon, it is worthwhile to look a bit harder for MS than more benign disorders, or equally devastating ones in which there is no effective treatment (such as PSP).
Perhaps the biggest problem with diagnosis of MS is that it common to confuse an MRI with lots of white matter lesions with MS. To have MS, one needs to have objective signs of MS. More about this is on this page concerning white matter lesions in Migraine, which is massively more common than MS, and often has plenty of white matter lesions as well.
Patients with MS generally do NOT present with vertigo or hearing loss, but in the context of our dizziness specialty clinic, much more commonly present with a cerebellar syndrome. Like all dizzy patients, they are unsteady on tandem Romberg testing. In addition to this, there are generally specific oculomotor findings such as an internuclear ophthalmoplegia (see figure below), extreme impairment of smooth pursuit, rebound nystagmus, and ocular dysmetria. In fact, without objective signs of CNS lesions, one really cannot make the diagnosis of MS.
The general neurological examination is particularly important in MS, as opposed to other types of dizziness, as one is looking for multiple neurological lesions. Reflex asymmetry, upgoing toes (Babinski sign), unilateral sensory disturbances, spasticity, and evidence of optic neuritis (pale disk or Marcus-Gunn pupil) are all common.
|Large MS plaque in 8th nerve root entry zone in brainstem.||MS plaque similarly disposed in the middle cerebellar peduncle.||Two MS plaques in cerebellar white matter.|
Screening for MS is generally easy, because MRI scanning as well as the general neurological examination is very sensitive to MS. One looks for multiple white matter lesions separated in time and space. On the MRI, when there are "innumerable" white matter lesions, scattered throughout the brain and spinal cord, MS is possible (see MRI's below). That being said, it is important to emphasize that an MRI showing multiple white matter lesions is not equivalent to MS (Brownlee et al, 2018). Migraine is a very common disorder that can have many white matter lesions. In migraine, there are no objective neurologic finding, and the spinal tap is also normal. There are far more persons with white matter lesions due to migraine than due to MS, because about 14% of the entire population has migraine -- i.e. 1/7 people. This far exceeds the prevalence of MS (about 1.5/1000). So MRI scans can suggest MS, but actually their main utility is to rule it out (with a normal scan).
When there are just a few white matter lesions, the differential diagnosis is wide -- depending on the clinical situation, one may attribute them to "small vessel disease" (tiny strokes), the ravages of age, and of course, our ever present migraine. Tumors can usually (but not always) be distinguished from MS because they are "space occupying", meaning that they push surrounding brain tissue to the side. Neurosarcoidosis is distinguished from MS mainly through discovery of lesions elsewhere in the body. Neurosarcoid is exceedingly rare as well.
|Multiple MS plaques in white matter just above ventricles||Dawson's "fingers" extending from the ventricles seen in this woman with longstanding and classic MS.||Another illustration of Dawson's fingers, just above the lateral ventricle, seen on this sagittal view.|
Peculiarly, although MRI scans are widely available, in our setting in Chicago Illinois, as of 2019, the cost of MRI's has been rising very rapidly. We have seen hospitals charge as much as $7000/scan billed to insurance. As just a year ago, MRI scans were much cheaper, and one would think that costs should be coming down, comparison shopping is recommended. Our thought is that a "reasonable" price for an MRI is $700 or less.
We recommend that someone having a scan for MS select a closed unit (i.e. no "open" MRI's), a high-field scanner (1.5 Tesla or more -3T is preferable), and be sure that T1, T2, gadolinium contrast, and flair sequences are included in the study. This is very routine, and one generally only gets something different if one goes to an "open MRI" facility. The radiological diagnosis of MS is not "rocket science", and except in very complex cases, a neurologist should be able to tell you to a high degree of reliability whether or not your MRI and clinical picture is compatable with MS. If your MRI is normal, MS is very unlikely. If it shows lots of white spots, more consideration is needed.
Certain patterns of lesions are "classic" for MS. Dawson's fingers are projections from the ventricles (see above).
CT scans of the brain or spinal cord are not very good for diagnosing MS, because they do not show MS plaques very clearly, and they are used only when an MRI is not possible. This might be due to a person having a pacemaker or metal objects of some kind in their head.
|Increased signal in periaqueductal gray region (no obvious signs or symptoms due to this).|
Occasionally a lumbar puncture (spinal tap) is used to provide additional information. Here one looks mainly for increased gamma-globulin and an increased number of oligoclonal bands. The procedure also has some value in excluding other conditions such as meningitis or disseminated tumor. In the author's clinical practice, a lumbar puncture is rarely performed, but instead a watchful-waiting strategy of getting repeat MRI scans at roughly one year intervals for a few years is used. If there is no change in exam or scan, then I stop scanning.
|Oculomotor testing documents an in INO (internuclear ophthalmoplegia) individual with MS. Also see the accompanying movie. INO's are common in MS, and rare in nearly every other disorder involving dizziness.|
Audiological testing and MS.
Otologic testing for MS is generally normal. Hearing testing should be normal, as should be caloric testing and OAE's. The oculomotor parts of the ENG or rotatory chair test can be diagnostic, as in the figure above illustrating an INO, but see the next paragraph for the pitfalls. Brainstem auditory evoked responses (ABR) are also, generally speaking, normal. It is too soon to say whether VEMP's are helpful, but it seems likely that they will generally not be useful, because of the multifocal nature of MS. If you can get a reasonably priced MRI, we see little reason for bothering with a ABR, as the MRI covers all of the disease processes that might be diagnosed by a ABR, as well as many others.
While the ENG battery has some testing aimed at diagnosis of central lesions, the ability of audiologists who generally perform these tests is variable, with false positives and false negatives abounding. The problem is that because MS is such a rare source of dizziness, the people who usually do the testing and interpretation (audiologists), have very little experience in recognizing it. Our suggestion - -if an audiologist reads your ENG as showing "central signs", show it to a neurologist who is familiar with these things. On the other hand, if there is good evidence for MS on your clinical examination, and your ENG is read as normal, again show it to someone who is familiar with both MS and ENGs -- this is usually an otoneurologist. Otolaryngologists, like audiologists, are generally unfamiliar with MS. In our opinion, the optimal testing arrangement is one in which an experienced individual performs the ENG, and an experienced otoneurologist reads it.
Another difficulty with ENG's oculomotor testing is that they may not use large enough eye displacements to detect an INO. One should ideally use 40 degree saccades. It is common for newer ENG's to use 15 degree displacements or even less to avoid nonlinear artifact. This means that the bedside examination may be more sensitive than recordings (sadly enough).
There are presently many immunological treatments of MS, largely involving use of interferon or other immunosuppressants. We will not cover this in any detail, but this is the reason why it is worthwhile spending some effort on diagnosing MS.
Otherwise, treatment of dizziness accompanying MS follows the general strategy as treatment for central vertigo. The most useful medications are benzodiazepines (see article on drug treatment of dizziness). Vestibular rehabilitation is usually worth trying.
Treatment of tinnitus accompanying MS also generally follows the same strategies as for tinnitus in other contexts.