The successful treatment of vestibular disorders includes comprehensive examination, testing, and the proper exercise prescription.
By Himanshu Saini, PT, MHS
Vestibular rehabilitation is associated with the recovery and repair of lost vestibular function. This loss of function can cause dizziness, vertigo, and postural instability. All of these deficits can affect day-to-day life, decrease participation in activities, and increase the risk of falling.
In the clinical setting, therapists come across patients with dizziness, vertigo, or balance deficits who may benefit from vestibular rehabilitation by increasing the utilization of their vestibular system. In cases where improvement in the vestibular system is not anticipated, compensatory strategies can be taught to overcome the balance deficits and/or to reduce dizziness and vertigo.1
Nearly 35% of adults over the age of 40 experience a vestibular problem. The incidence is reported to be higher with advancing age.2 Stroke, multiple sclerosis, tumors, or trauma may cause vestibular deficits by involving the central vestibular structures such as vestibular nuclei, cerebellum, and the higher cortex.1 Among central causes, acquired traumatic brain injury (concussion) is the most common cause of dizziness or postural instability.3
Labyrinthitis vestibular neuritis and unilateral or bilateral vestibular loss come under the umbrella of peripheral vestibular disorders that result from the involvement of the vestibular part of the vestibulocochlear nerve. Another vestibular disorder, benign paroxysmal positional vertigo (BPPV), consists of nearly one-third of all the vestibular diagnoses commonly seen in the clinical setting.4 In patients, vestibular disorders can be very debilitating as they may increase fear of falling, dizziness, vertigo, and/or postural instability, resulting in decreased functional mobility and decreased participation in activities at home and in the community, which leads to further balance problems and deconditioning.1,2
Anatomy of the Vestibular System
The vestibular system can be divided into peripheral and central components. Peripheral components that are present in the inner ear comprise three semicircular canals that detect angular motion. The two otolith organs—the utricle and the saccule—detect linear motion. The vestibular nerve receives afferent information about the head position and its movement in space from these peripheral structures and transfers the information to the central vestibular components, nuclei in the brainstem, and cerebellum.
Information about body position also arrives in the brainstem from visual and proprioceptive sensory systems. All the afferent information is integrated here with the input from higher cortical centers, and the efferent command is sent back to the eyes and the rest of the body to make appropriate adjustments to maintain balance and equilibrium. Efferent commands travel to the eyes via the vestibulo-ocular reflex (VOR), which maintains vision clarity with head movements on a target, and to the rest of the body via the vestibulo-spinal reflex, which maintains balance against postural perturbations.1
Physical Therapy Examination
Most patients with vestibular problems are referred to physical therapy by a variety of clinicians, such as neurologists, physiatrists, family physicians, and most commonly an ear, nose, and throat physician who specializes in vestibular disorders.
The most important component of the vestibular examination is a detailed history that can help point the therapist in the direction of a possible cause of dizziness/vertigo/falls. Therapists need to pay attention to whether vertiginous symptoms are increased by position change, motion, and head movements in darkness and/or while driving. Nystagmus is a commonly observed clinical sign in vestibular problems. The duration, frequency, and latency of nystagmus can help to delineate the vestibular pathology.1,5
Medical evaluation helps to quantify the vestibular loss with the use of bithermal caloric testing, rotational chair test, and electronystagmography. An electronystagmogram is used to assess occulomotor smooth pursuit and saccadic eye movements. It provides information regarding the structure responsible for the vestibular deficit.
The rotatory chair test and the bithermal caloric test are useful in assessing VOR function.1,6 The rotatory chair test in particular is used to test bilateral vestibular functioning. This test is performed in a dark room with the patient sitting in a chair, his head stabilized, and his eyes open, with the chair rotated bilaterally at different speeds. In Bithermal caloric testing, the external auditory canal is filled with either hot or cold water/air to develop a temperature difference that produces the movement of the endolymphatic fluid.
Eye and Vestibulo-Ocular Reflex Examination
Occulomotor movements are examined to assess for smooth pursuit, saccadic eyes movement, convergence, and divergence. Any reproduction of symptoms may indicate central nervous system pathology.
The therapist tests the VOR for slow VOR, VOR cancellation, and VOR head thrust. Another test that can help to diagnose difficulty with the VOR is dynamic visual acuity testing, in which the patient reads letters on Snellen Charts with and without head movements. A difference of more than two lines may indicate VOR pathology. Any abnormality in VOR testing can identify a potential problem in the peripheral vestibular system, which can result in gaze instability when a patient’s head is in motion.5
Benign Paroxysmal Positional Vertigo Testing
Testing for BPPV involves the Dix-Hallpike test for anterior and posterior canal BPPV, and the Roll Test for horizontal canal BPPV. Modifications can be made during testing to accommodate for neck or back problems. During the Dix-Hallpike assessment, the patient is taken through multiple positions while the therapist looks for nystagmus or reproduction of the patient’s symptoms to diagnose the affected canal. During testing, Frenzel lenses can be used to prevent eye fixation to help therapists look for the nystagmus.1,5
Testing for Postural Instability and Falls
Devices that use force plates and are designed to provide objective assessment and retraining can be performed for patients who present with postural instability or have a history of falling. The following tests can be performed on such devices to assess a patient’s ability to use sensory and motor systems for balance.
Sensory Organization Testing (SOT) assesses the ability to use somatosensory, visual, and vestibular inputs for balance. SOT also gives information on the center of gravity alignment and dominance of either ankle or hip strategies.
The Motor Control Test, in which the platform provides forward and backward perturbations, test latency and amplitude of the muscle response. It also helps to delineate if one group of muscles are particularly responsible for the balance problems.
In addition, the Adaptation Test moves the platform either up or down, simulating outdoor uneven terrain, providing an unexpected quick challenge. This test also checks latency and amplitude of the muscle response.7
Tests and Treatment
The Timed Up and Go, Berg Balance Assessment, Functional Reach, Balance Evaluation Systems, Dynamic Gait Index, Functional Gait Analysis, and Activities-Specific Balance Confidence tests help to evaluate for safety and independence with functional mobility, and can also be used to track a patient’s progress.1,5
Research demonstrates that rehabilitation improves outcomes in patients with a vestibular diagnosis, especially when the peripheral vestibular system is involved. However, new evidence is emerging
that shows promising benefits of vestibular rehabilitation in patients with a central pathology.1,8
Epley’s Maneuver—This has been shown to be effective in the treatment of posterior canal BPPV. It can also be used to treat the less commonly occurring anterior and horizontal canal BPPV. Patients are provided with list of movements to avoid for 2 to 5 days post-treatment to prevent the re-entry of otoliths (calcium particles) into the canal.1
Brandt—Daroff exercise can also be used to treat refractory cases of horizontal canal BPPV and to treat residual dizziness after successful treatment of BPPV with Epley’s Maneuver.1,4
Gaze Stabilization exercises are used in the presence of positive VOR to improve gaze stability with head movements. Progression with increasing head velocity should only be made as long as the target remains clear. A checkerboard pattern with single or multiple targets, and near and far targets, can also be used for progression.1,9
Habituation exercises are used to decrease the vestibular symptoms by repeating movements that reproduce a patient’s symptoms. These exercises help to desensitize the movements producing vestibular symptoms.1,10
Substitution exercises are used to train somatosensory, and/or visual components of balance in case of absent or decreased usage of the vestibular system, when vestibular recovery is not likely expected.1
Exercises for Postural Instability
Exercises to improve postural instability or balance problems include the use of somatosensory, visual, and/or vestibular inputs for balance. These are performed with eyes open and closed along with head movements. In addition, the use of various surfaces are encouraged to stimulate the vestibular, visual, and somatosensory system for balance. Various products like balance cushions, Dyna Discs, and floor mats may be used to provide a compliant surface for these exercises.1
Many other vestibular exercises can be used to improve usage of the vestibular system or to work on compensatory strategies to improve balance and safety. Therapists can be very creative in improvising exercises to make it fun and challenging to their patients. A good vestibular program includes a combination of the above exercises to improve vestibular recovery, adaptation, and/or compensation.1,10 PTP
About Rehabilitation Hospital of Indiana
Rehabilitation Hospital of Indiana (RHI) is a twenty-two year community collaboration between Indiana University Health and St. Vincent Health. RHI has five locations to serve patients, offering a full range of acute inpatient, outpatient and vocational rehabilitation services for adults with life-changing illness and injuries due to brain injury, spinal cord, stroke, amputation, orthopedic conditions, neuromuscular disease, burns and related disabilities.
Himanshu Saini, PT, MHS, graduated from the University of Delhi with a Bachelor of Physical Therapy degree in 2006, and then from the University of Indianapolis with a Master of Health Science degree in Post Professional Physical Therapy in 2009. Presently, Saini works as an outpatient staff physical therapist at the Rehabilitation Hospital of Indiana in Indianapolis. Saini specializes in vestibular rehabilitation. For more information, contact [email protected].
Vestibular and Balance Assessment Technologies Help Drive Recent Research
Devices designed to assist in vestibular rehabilitation and evaluation helped researchers gather vital data for studies published recently in the allied health care literature. Among the studies published since 2013, many were aided by some of the latest vestibular technologies.
One such study published in February 2014 focused on exploring the effect of vestibular stimulation on eye-hand coordination and postural control in elite basketball players.1 For this study, researchers used the System 2000 Rotational Vestibular Chair from Micromedical Technologies Inc, Chatham, Ill. The chair is built to measure vestibular-ocular reflex (VOR) from 0.01 to 1.28 Hz at velocities up to 300 degrees per second. It is also designed to accurately accelerate and change direction without inertial artifact.
This study of athletes required each participant to perform a standing balance test with concurrent fast finger pointing task toward a moving visual target three times. Vestibular stimulation with a rotational chair was then performed on the study subjects, and the same exercise was repeated. The researchers determined that after vestibular stimulation, the study subjects had shorter reaction times in eye-hand coordination tasks, and regained posture control more rapidly.
In a different study, researchers examined whether postural-control deficits persist beyond the acute state among individuals who have a history of mild traumatic brain injury (mTBI).2 Key data for this study was provided by the NeuroCom Sensory Organiztion Test (SOT) postural-assessment battery—an objective assessment protocol associated with the SMART Balance Master, available from Clackamas, Ore-based NeuroCom, a division of Natus. The SOT assessment provided a composite balance score, a visual ratio score, a somatosensory score, and a vestibular score.
Conclusions from this test determined that individuals who had a history of mTBI demonstrated altered postural dynamics. Likewise, it determined those who had no history of mTBI did not exhibit altered postural dynamics. The study’s authors believe the results of this test support the idea that changes in cerebral function that affect postural control may continue well after an acute injury resolves.
A third study was aided by the Biodex Balance System, offered by Biodex Inc, Shirley, NY, which helped researchers gather vital data to investigate balance and postural stability.3 This investigation was led by a DePauw University-based team that looked to the Biodex Balance System to assess the validity and reliability of limits-of-stability test. The main outcome measures provided by the device included directional control and test duration. The researchers acknowledged that the Biodex Balance System provided unique information for their testing, and recommended a similar study be continued with a clinical population to explore even deeper into this topic.
These studies represent only a portion of the product lines built for vestibular assessment. Among the products available to physical therapists in this area of practice are also those such as the Korebalance line, available from Fallbrook, Calif-headquartered Med-Fit Systems Inc. These devices use virtual and interactive technology, feature Korebalance software for balance and vestibular assessment, and are available in configurations that can be portable or clinic-based.
Vestibular research is an area of considerable activity. Though some of the conditions associated with vestibular disorders are still not well understood, evolving technology in this field assures that researchers have the tools to collect reliable data to help answer important questions.