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BRAINSTEM WHITE MATTER LESIONS (BWM)

Timothy C. Hain, MD. Page last modified: March 17, 2013

Causes of brainstem white matter lesions:

Getting older: Age is the single most common "cause" of BWM, although in reality this is an association. This is presumably a "wear and tear" phenomenon.

Small strokes: Brainstem strokes are attributed to "small vessel disease". These are generally attributed to hypertension or hyperlipidemia.

MS and related conditions: Demyelinating disorders such as multiple sclerosis can cause BWM.

Consequences of brainstem white matter lesions for dizziness and imbalance.

The brainstem is "tightly packed", and one would expect that brainstem lesions, even small ones, could have serious consequences to balance, motor control, and function of the nerves in the head (e.g. cranial nerves). There are an immense number of subtle functions of the vestibular system, such as coordinate rotation between the head and body, that might be disrupted by brainstem lesions. Slowing down of neural transmission through the brainstem might also be disruptive to "rapid" responses such as the VOR. An example of a "slowing down" type disorder is internuclear ophthalmoplegia, which is due to a midline brainstem lesion in a vulnerable long track, the MLF.

In our experience, the most common clinical correlate with BWM is simply unsteadiness. It is rare to see lesions so big as to be called "strokes". It may be that this is a self-selection process however, as the practice of the author is not focussed on stroke.

According to Jacobson, these sorts of lesions are associated with decreased velocity storage -- or in other words, a decreased time constant of the vestibulo-ocular reflex (Jacobson et al, 2004). This study was of a prospective nature, and for this reason, was small (and thus the conclusion is tentative).

Treatment:

Practically, BVM may be associated with unsteadiness. As once you have them, they are there for life, prevention is the main goal of treatment. We advocate attention to reducing vascular risk factors, and especially controlling labile hypertension. Reducing elevated cholesteral, and strict control diabetes is probably helpful too. Small amounts of vitamin b6 (pyridoxine) supplementation also seem reasonable (i.e. 2 mg/day). It is not clear if daily aspirin intake is useful or harmful in persons with PVM, and in our opinion, the decision should be made on an individual basis. Beta blockers such as propranolol and related medications may be especially suitable to prevention of spikes in blood pressure. These drugs are also cardioprotective.

In persons with migraine, we generally suggest a prophylactic regimen such as a combination of low-dose aspirin and a migraine prevention agent such as verapamil. It is not known whether this treatment regimen is effective. Beta blockers would also seem very reasonable.

Treatment of the demyelinating diseases may be possible, but is outside the scope of this brief review.

With respect to the common symptom of unsteadiness, empirical treatment including physical therapy. While generally medications are not helpful in situations where fiber tracts or neurons have died, in some occasional cases, trials of medications such as antidepressants or anti-parkinsonian drugs are helpful.

References:

Copyright August 3, 2016 , Timothy C. Hain, M.D. All rights reserved. Last saved on August 3, 2016