GUEST COLUMN: Vestibular Rehabilitation: Controversies & Consideration - DR.CARLTON PEREIRA

Most people don’t find it difficult to walk across a gravel driveway, transition from walking on a sidewalk to grass, or get out of bed in the middle of the night without stumbling. However, with impaired balance such activities can be extremely fatiguing and sometimes dangerous. Imbalance are common complaints in both the adults and the general population. The patient who complains of Dizziness often presents a diagnostic and management dilemma to the attending ENT, Audiologist or Physiotherapist. The Cause of Dizziness can range from benign self-limiting conditions to potentially life threatening conditions.

Dizziness and Disequilibrium can occur from disruptions in one or more of the sensory systems required for balance or from inadequate integration and central processing of information received from these sensory systems.The visual and somatosensory reference information is constantly changing as a function of movement, but the vestibular reference ‘’Gravity” is unchanging. As long as the information arising from these sources is predictable and nonconflicting, equilibrium is maintained and there is little thought of balance. When a conflict occurs the brain must efficiently and quickly adjust the level of priority given to the conflicting incoming information or a sensation of imbalance might occur.

Benign positional vertigo, believed to be the most common type of peripheral vertigo, can be seen following head injury, vestibular neuronitis, stapes surgery, Meniere’s disease, or can present alone.  The disorder is thought to be related to an abnormality in the association of the otoconia to the cupula within the membranous labyrinth, resulting in abnormal responses to endolymph movement with head motion. Symptoms are typically associated with head movement, such as rolling over or getting in or out of bed.  The associated vertigo is brief, lasting only seconds in duration, and can be seen as an acute form only or in an intermittent or chronic form. The DixHalpike test is a confirmatory test for BPPV.

Labyrinthine infarction leads to a sudden profound loss in auditory and vestibular function, and typically occurs in older patients.  This phenomenon can be seen in younger patients with atherosclerotic vascular disease or hyper coagulation disorders.  Episodic vertigo may herald a complete occlusion in the form of a type of transient ischemic attack.  After complete occlusion, the acute vertigo that ensues will subside, often leaving the patient with some residual unsteadiness and disequilibrium over the next several months while vestibular compensation occurs.

Vestibular Neuronitis presents as a sudden episode of vertigo without hearing loss in an otherwise healthy person.  The disorder can occur as a single attack or can present as multiple attacks.  It occurs more often in spring and early summer, and as a result is often associated with an upper respiratory tract infection developing around the same time.  The onset of vertigo is sudden and is typically associated with nausea and vomiting, and can last for a period of dayswith gradual improvement over the following weeks.  The disorder is often followed by episodes of benign positional vertigo.

Labyrinthitis is an inflammatory process occurring within the membranous labyrinth that may have a bacterial or viral etiology.  Viral infections produce symptoms of dizziness similar to vestibular Neuronitis, except that there is cochlear dysfunction as well.  Congenital measles, rubella, and cytomegalovirus infections frequently cause no vestibular symptoms. On the other hand the Bacterial variant can be associated with dizziness, tinnitus and even discharge.

Meniere's disease is an inner ear disorder characterized by episodic vertigo attacks, sensorineural hearing loss, tinnitus, and pressure or fullness in the involved ear.   The attacks are characterized by true vertigo, usually with nausea and vomiting lasting hours in duration.  Histopathologically, this disorder is believed to be due to dilation of the endolymphatic spaces (hydrops) with ruptures and subsequent healing of the membranous labyrinth.The vast majority of migraine variants are made up of the first two categories, migraine without aura, and migraine with aura. The term aura can be defined as a focal neurological disorder. Auras generally are considered to be abnormal sensory perceptions. Visual auras are the most frequent type, and may come in a wide variety of phenomena or hallucinations.

It is valuable for healthcare professionals to have at least a basic understanding of migraine and audiovestibular symptoms. Vertigo, tinnitus, photophobia, and phonophobia, and occasionally hearing loss may present in at least 30% of migraine patients. Although hearing loss in migraine patients is less common than in vertigo, tinnitus, photophobia, and phonophobia, it may present as a low frequency fluctuating sensorineural hearing loss. It is possible, however, to have a permanent hearing loss or vestibulopathy (as indicated by caloric weakness) secondary to a migraine attack. The commonality of these symptoms, often make it difficult to distinguish the disorders on clinical grounds alone. 

This collection of symptoms may first be thought as consistent with Meniere’s disease, or other types of inner ear involvement, such as a recurrent vestibular Neuronitis, particularly in patients with recurring episodes or attacks. The differential diagnosis of migraine and Meniere’s disease, then, may often present as a diagnostic enigma.  In addition, 60% will report a lifelong history of motion sensitivity. Interestingly, the incidence of Meniere’s disease is twice as prevalent in migraineurs, as in the general population. The diagnostic challenge is further complicated if a differential diagnosis of multiple sclerosis (MS) is included. The initial onset of acute, debilitating vertigo will appear as the initial symptom in 5% of MS patients. As many as 50% of MS patients will experience at least one occurrence of acute vertigo at some time during the course of the disease. This may also be compounded by the fact that one in ten MS patients may present with hearing loss, which may be partial or complete, but often recovers, similar to the migraine or Meniere’s patient.

Mal de Debarquement, or disembarkment sickness, is actually a common and normal occurence. It can best be defined as the continued sensation of motion, rocking, or swaying that persists after return to a stable environment following a prolonged exposure to motion, as one would encounter on cruise, car, bus or train ride. This sensation may only last hours or even for a few days. The Mal de Debarquement sensation that commonly occurs is independent of any seasickness or motion sickness that may be experienced during the cruise or travel. The individual may not have any ill feelings at all, and only notices the rocking sensation once on solid ground

DIFFERENTIATING AMONG COMMON CAUSES OF VERTIGO

 

 

Condition

Differentiating  symptoms

1

peripheral vertigo

more severe & associated with auditory symptoms (e.g., tinnitus, hearing loss), as well as nausea and vomiting

2

Central causes of Vertigo

Associated with diplopia, weakness, numbness, or incoordination.

 

3

Benign positional vertigo

Lasts only seconds

4

 Vertebrobasilar insufficiency or migraines.
 

 

Begins abruptly and lasts minutes

5

Meniere’s disease

Heightens in severity over a period of minutes, but lasts for several hours with a gradual improvement over several hours. 

6

Vestibular neuronitis  & labyrinthitis

Fairly abrupt onset  (over a period of hours) with resolution of the acute phase over the next several days.

7

Traumatic injuries or vascular infarction of the labyrinth

sudden onset  with a slow recovery from the acute phase over a period of days to weeks, often with residual effects over a period of 12 to 18 months.

 

 

Treatment of Vestibular Dysfunction-  Treatment for vestibular disorders has historically fallen into three categories.

a) The medical treatment of symptoms and underlying pathologic conditions.

b) The Surgical stabilization of the end organ or vestibular nerve through reparative or ablation technique.

c)  Observation, reassurance, and counseling to learn to live with it.

Vestibular Rehabilitation (VR) offers an alternate form of treatment to many patients who previously would have fallen into one of these three categories. Treatment of vestibular disorders through exercise and repositioning technique has gained popularity within the last decade and recent literature supports the efficacy of these approaches

Controversies in Vestibular Rehabilitation

Despite evidence suggesting that VR is more effective and medication is less effective for most chronically dizzy patients, most dizzy patients are still treated with medication.

Critical Period of Compensation- The period of time varies across a broad spectrum of factors.

Rehabilitation versus Repositioning- Studies show that especially in the case of BPPV (Benign Paroxysmal Positional Vertigo) there is better benefit from single reposition treatment rather traditional habituation modalities.

Vestibular Rehabilitation versus Medication- The use of centrally sedating medication may in fact impede the benefits of VR therapy. Reports show that patients taking vestibular suppressants, antidepressants, tranquilizers, and anti consultants ultimately achieve the same level of compensation as patients not taking similar medication, but the length of therapy is significantly longer.

Generic Vs Customized Exercise-  Although the concept of exercise treatment for dizziness is gaining popularity access to VR remains limited. The difficulties encountered  by patients in trying to find VR facilitates and the time commitment required to attend such regular sessions may decrease patients compliance. Studies show a much better acceptance for Customized exercises.

Adaptive Strategies- Patients with loss of vestibular function either unilateral or bilateral adopt a number of strategies to increase gaze stability with head movement. In such patients some behavioral changes and substitution of vestibular responses take place.

Cervico-Ocular Reflex Input-  The cervico-occular reflex is thought to be a compensatory reflexive eye movement in response to stimulation from the ligaments, muscles, and joints in the neck.In the absence of vestibular function the COR appears to take on the role of the vestibulo-occular  reflex in head-eye coordination in initiation of the Anti-compensatory saccades which take the eyes in the direction of the target and the generation of the subsequent slow compensatory eye movements.

Modification of Saccades- Saccades are the fastest eye movements. Saccades allow patients to refixate their gaze with minimal duration of retinal slip.The Saccades can be voluntary or involuntary. Central programming of the eye movements occur when a patient with vestibular loss moves his or hers Head. These patients make a voluntary saccade contra lateral to the direction of head movement to compensate for the inefficient VOR response.

Modification of Smooth Pursuit-  Smooth-pursuit tracking, or visual following, allows for gaze stability on objects moving through the field of vision. This type of eye movements is modulated by the cerebellum and can function alone while the head is still or can interact with the VOR to assist in gaze stability while moving.

Substitutution of Sensory Imputs and Decrease Head Movements- Following the loss of vestibular function bilaterally, there is ‘’reweighting’’ of priority and dependence on visual and somatosensory inputs for the maintenance of balance and postural control. Initially there is a shift towards visual dependency. While walking patients may visually lock on to the targets and use this locking on to provide information about relative motion. A deficient VOR is not an issue when the head is not moving, therefore, some patients develops a strategy of avoiding any rapid movements of the head to avoid symptoms of retinal disc slip.This Strategy does not allow the natural compensation process to take place and does not alter the fact that the when the head is inevitably moved quickly, symptoms will ensue

Planning Goals- In establishing reasonable goals and planning a therapy program suitable for a patient, the clinician must take into consideration a number of variables, including the following. A working diagnosis.The patient’s specific complaint and concern regarding lifestyle limitation. Any permanent Impairment not amenable to therapy. A realistic expected level of improvement. The clinician’s concern regarding patient safety and the risk of falling

The plan for each session should include

Objectives :  A description of the activity the patient will perform,  criteria for acceptable performance, and goal and functional outcomes to be achieved.

Methods and Materials :  The name of the exercise to be performed, including specific conditions under which the patient is to perform (i.e., speed, time, position, range of movement) Also included would be any material required (e.g., physioball, mirror, targets, foam pad)

Results :  Documentation of the patient’s performance viz; any dizziness, nausea, or inability to perform any task to completion. 

Plan for the next session : Progression or modification of the exercise to challenge or help the patient’s performance.

Treatment Strategies of Vestibular Rehabilitation are to; Minimize symptoms and functional disability, Increase mobility and independence, Reduce the risk of fall and injury.

Reasonable therapy goals may be dictated by Patients  specific functional limitations as well as residual vestibular function.

Summary- With the advent of Computer-based diagnostic capabilities and nearly instant Internet access to current research, continued use of “conventional wisdom” in the evaluation and treatment of vestibular patients must be superseded by the latest evidence based technique. The most successful treatment for treatment of vestibular disorders these days lie in the acceptance of evidence based approaches to treatment by all the treating Doctors involved be it Neurologist, ENT Physicians or Physiologist, This and this alone will enable us in managing the unique and ubiquitous world of Vertigo.

In Conclusions: The methods and standardized treatment for vertigo are rapidly changing with gaining pace with our global evolution. A new era is being drawn on where vestibular managnent will have an equal management by both us physicians and physiotherapist. Custom made rehabilitation programs will need to be chalked out for each and every patient of vertigo for which a greater and disciplined regime of exercises will be incorporated. It is the physiology of cognition and physiotherapist rehabilation working hand in hand which will help us provide the optimum treatment discipline in vertigo management.

 

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