Let’s spend the next few weeks reviewing the implications, symptoms, recovery process and rehabilitation techniques available to people who suffer acute vestibular dysfunction. Now, I am not talking about BPPV patients here. I will discuss the recovery from BPPV later in the series.
This series will discuss patients with permanent, or at least long-lasting or chronic, vestibular weakness such as those dealing with Vestibular Neuritis or Labyrinthitis, chronic Meniere’s disease and residual unilateral weakness, or bilateral vestibular weakness. For today, I just want to establish some terminology and definitions.
The following terms are used to describe various aspects of the recovery process. Here is how I use them:
Vestibular Rehabilitation is the process of training the patient in techniques to promote recovery from vestibular injury. The techniques should be based on a combination of the specific vestibular disorder, a working knowledge of what parts of the vestibular/balance system are healthy, and the patient’s specific complaints, abilities and goals.
Vestibular Adaptation describes the response of the Central Nervous System (CNS) to prolonged asymmetrical peripheral vestibular activity. Later in this series, I will discuss the process of cerebellar clamp, reduction in gain of the Vestibular Ocular Reflex (VOR), and the gradual restoration of gain over time.
Vestibular Habituation refers to the long-term reduction in response to stimulus from repeated exposure. Initially, exercises for BPPV were designed to habituate or desensitize the patient by repeatedly moving the head to the position that provoked symptoms. The researchers soon determined that patients were getting better for other reasons. Since the word “habituation” is unfamiliar to many readers, I provide here the Wikipedia definition: “Habituation is a form of learning in which an organism decreases or ceases to respond to a stimulus after repeated presentations.”
Vestibular Compensation consists of the entire repertoire of strategies used by a patient to reduce symptoms. These strategies may include adaptation, substitution, alternative predictive, cognitive or avoidance strategies.
The following excerpt from the American Physical Therapy Association, Neurology Section webpage summarizes the above terms rather succinctly.
Vestibular Rehabilitation (VR) has been shown to be effective in reducing
symptoms and improving function for patients with vestibular disorders. The
goal of VR is to promote central nervous system compensation through
exercise-based strategies. Three exercise approaches are used to reduce
impairments (dizziness, postural instability, and gaze instability) and promote
return to function.
Visual-vestibular interaction exercises, or adaptation exercises,
encourage the adaptation of the remaining vestibular system to certain stimuli (i.e.,
head movement). They are mainly used to treat persons with complaints of gaze
instability and have also been shown to reduce dizziness and improve balance.
Substitution exercises are used to promote balance and reduce falls by using other
sensory stimuli (e.g., visual or somatosensory input) to substitute for absent or
reduced vestibular function.
Habituation exercises are used to reduce movement/
position-induced dizziness through repeated exposure to noxious stimuli. By
systematically producing mild, temporary symptoms, a reduction of dizziness can
result over time.
Photo courtesy of http://theconcussionblog.com/tag/recovery/