Timothy C. Hain, MD Page last modified: December 28, 2014
Supplemental material is on the site DVD
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).
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.
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.|
Diagnosis of 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 very likely (see MRI's below). When there are just a few white matter lesions, the differential diagnosis is much wider -- depending on the clinical situation, one may attribute them to "small vessel disease" (tiny strokes), the ravages of age, 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.
|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.|
Peculiarly, although MRI scans are widely available, in our setting in Chicago Illinois, as of 2/2012, 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.
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 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, which is also on the site DVD.|
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 MS. 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. 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.