The majority of patients who report experiencing an acute vestibular syndrome (i.e.,
neuritis or labyrinthine impairment) will be symptom free after a few weeks. There
are those, however, who continue to experience symptoms even following medical treatment
and therapy.
This is extremely frustrating to both the physician and the patient. In fact, it has
been reported that approximately one quarter of patients develop a persistent dizziness
disorder following the initial event. This statistic is in line with episodic refractory
vestibular disorders (e.g., vestibular migraine and Menière’s disease) and is even
higher in those individuals who have incurred a mild traumatic brain injury (mTBI).
While each patient’s set of symptoms may vary with chronic dizziness (i.e., non-vertiginous),
they will often describe the symptoms as being continuously present throughout the
day and the severity of the sensations may vary in intensity. They will also frequently
describe the subjective sensation of an internal rocking or unsteadiness that they
liken to being on a dock in a calm lake.
Patients with chronic symptoms of dizziness may also describe the sensation of pulsion
or even report brief episodes of rotary vertigo. Another key feature often observed
in patients that suffer from chronic dizziness is sensitivity to visual motion. Specifically,
motion-rich environments, environments with complex visual patterns or situations
during which they are moving their head, are particularly provocative. These symptoms
have been shown to have a profound effect on the patient’s quality of life and daily
functioning.
When studies are done that examine the relationship between the severity of symptoms
in patients with chronic dizziness and the extent of the peripheral vestibular impairments,
the two are poorly correlated. This would seem to indicate that what is driving the
persistent symptoms are higher-level brain processes and not the status of the peripheral
structures.
This runs counter to previous theories that attempted to explain chronic dizziness
as “chronic vestibulopathy” (CV). The driving theory behind CV was, for reasons that
are unclear, that the compensation mechanisms of the vestibular system were impaired
such that complete compensation for the insult could not be achieved.
While this concept was adopted for decades, new studies have found that the story
may, in fact, be more complicated. Research over the last few decades have shown that,
rather than simply being a case of impaired central nervous system compensation, distinct
changes in the way the brain processes spatial information may be the primary contributor
to the symptoms.
Specifically, the processes that govern the coordination of postural control and the
integration of sensory information may be disrupted, which results in a continuation
of these persistent symptoms.
There are a number of laboratories that have studied and described these chronic clinical
entities that are debilitating to the patient. Terms such as visual vertigo, space-motion
discomfort, and chronic subjective dizziness are just a few of them. More recently,
a criterion was published for persistent postural perceptual dizziness (PPPD), a disorder
characterized by many of the symptoms described above ([Staab et al, 2017]).
In this month’s issue of the Journal of the American Academy of Audiology, Fox and colleagues, in their article titled “Dizziness, Vertigo, and Mental Health
Comorbidity in Gulf War Veterans,” tackle the problem of dizziness and mental health
comorbidity in veterans diagnosed with Gulf War illness.
The investigators sampled 50 veterans and characterized their symptoms associated
with dizziness and vertigo and catalogued their mental health comorbidities. This
study illustrates how we must begin to look beyond just the structural impairments
that are identified by laboratory testing and treat the patient as a whole.
I encourage you to read this well-designed study. I am excited to see research of
this type and caliber being applied to patients with chronic dizziness.
Devin L. McCaslin, PhD
Deputy Editor-in-Chief
