Balance Disorders

A functioning balance system allows a person to move through the environment without falling and to be aware of one’s physical position about gravity. The human balance system is complex. It includes input from and coordination of three sensory systems: vestibular, visual, and somatosensory. Disturbances to one or more of these systems may result in a balance system disorder, which can hurt balance and/or cause symptoms such as dizziness.

The term “dizziness” is nonspecific and can refer to a range of symptoms, such as light-headedness or vertigo (sensation of motion, such as spinning, swaying, or rocking). Symptoms of balance system disorders can be uncomfortable, inconvenient, and limited to activities of daily living (Ten Voorde et al., 2012) and can increase fall risk (Graafmans et al., 1996; O’Loughlin et al., 1994; Rubenstein, 2006).

Assessment and management of balance system disorders and their symptoms is an interprofessional endeavor, at times involving audiology, behavioral health, cardiology, neurology, neuro-ophthalmology, neurotology, occupational therapy, otolaryngology, otology, physical therapy, and/or a primary care provider. Audiologists and speech-language pathologists may interact with individuals of all ages who complain of dizziness and/or imbalance.

The incidence of a disorder or condition refers to the number of new cases identified in a specified period. Prevalence refers to the number of individuals who are living with the disorder or condition in a given period.

Approximately 33.4 million adults in the United States report a dizziness or balance problem during the past 12 months (National Institute on Deafness and Other Communication Disorders, 2017). The true incidence and prevalence of balance system disorders in adults and children are unknown. This may be due, in part, to the wide range of symptoms attributable to balance disorders, the underlying cause(s), the length or frequency of the disorder, and the varied diagnostic techniques used for detection.

Adults

An epidemiological study conducted in the United States using data from the 2001–2004 National Health and Nutrition Examination Survey (Centers for Disease Control and Prevention, n.d.-a, n.d.-b) suggests that 35% of adults aged 40 years or older—approximately 69 million Americans—demonstrate some form of vestibular dysfunction when tested with a postural metric (Agrawal et al., 2009). A 2008 Balance and Dizziness Supplement to the U.S. National Health Interview Survey showed that 27.7% of adults aged 75 years and older experienced vestibular problems in the past year (Ward et al., 2013). A systematic review of the research by Murdin and Schilder (2015) identified that the rate of vestibular dysfunction increases with age, and women are more likely to experience dizziness and vertigo symptoms than men. Balance difficulties are a significant risk factor that contributes to falling injuries (Centers for Disease Control and Prevention, 2016), and more than 28% of adults over the age of 65 years reported falling at least once in the past 12 months (Bergen et al., 2016).

Statistics for balance system disorders can vary by type of disorder and how long it lasts. One study reported a 12-month prevalence of vestibular vertigo in adults to be roughly 5% and an incidence to be 1.4% (Neuhauser, 2007). From the 2008 Balance and Dizziness Supplement to the U.S. National Health Interview Survey, 20.6% of people reporting vestibular problems in the past 12 months demonstrated the features of benign paroxysmal positional vertigo (BPPV), and 1.4% of the same dizziness population presented with features of Ménière’s disease (Kerber et al., 2017).

Pediatrics

Dizziness and balance disorders can also occur in children (Rine, 2009; Wiener-Vacher et al., 2018). Responses to the 2016 Balance Supplement to the U.S. National Health Interview Survey for children revealed dizziness or imbalance symptoms in 5.6% of children ages 3–17 years, of which 40% had visited a healthcare provider to evaluate their symptoms (Brodsky et al., 2020). The rate of dizziness and vertigo in adolescents reaches adult levels (Langhagen et al., 2015). Children with hearing difficulties are more at risk for dizziness and balance problems (Li et al., 2016).

Signs and symptoms of balance system disorders vary due to a wide range of underlying causes. Signs and symptoms may be episodic, acute, or chronic and may include the following:

• confusion/disorientation
• difficulty concentrating
• falls/near falls
• fatigue
• gross motor and/or reflex delays
• headache
• imbalance/disequilibrium/unsteadiness
• impaired mobility/gait abnormality
• light-headedness/feeling faint
• motion intolerance/motion sickness
• nausea/vomiting
• nystagmus (reflexive eye movement)
• oscillopsia (visual disturbance in which viewed stationary objects or surroundings move coincident with active or passive head movements and may appear to be jumping or blurred)
• vertigo
• visual disturbances

Accompanying auditory symptoms may include the following:

• aural fullness
• autophony (hearing one’s voice or other self-generated noises as unusually loud)
• hearing loss (e.g., congenital, sudden onset)
• sensitivity to loud sounds
• tinnitus (see ASHA’s Practice Portal page on Tinnitus and Hyperacusis)
• vestibular hyperacusis/Tullio phenomenon (sound-induced imbalance, falling, and/or dizziness)

Functional modifications that may be observed include the following:

• limiting head movement
• requiring assistance in activities of daily living
• using an assistive mobility device
• walking slowly and deliberately

Pediatrics

Identifying children with balance disorders, vestibular deficits, or dizziness can pose additional challenges when compared to adults. The process of acquiring information from a pediatric patient will be different, as will the testing strategies. Often, children will not report symptoms and may be incapable of verbalizing the abnormal sensations that they are experiencing (McCaslin et al., 2011; Wiener-Vacher, 2008). Distinct differences may exist in symptoms of dizziness and balance disorders in the pediatric population as compared with adults. Vestibular system impairments in children may present as developmental delays in activities such as walking. Working with this population requires additional education and training.

The underlying causes of balance disorders and the resulting symptoms are many and varied. They include causes related to the vestibular system and causes related to other body systems and conditions. Conditions and events resulting in imbalance and/or dizziness may resolve spontaneously or may become chronic.

Causes of balance system disorders may include, but not be limited to, the following:

• acute injury to the vestibular system
• aging vestibular system
• alcohol and/or drug ingestion
• anatomic brain changes
• autoimmune inner ear disease
• benign paroxysmal positional vertigo (BPPV)
• circulatory or cardiovascular conditions
• cochlear implant surgery
• enlarged vestibular aqueduct syndrome
• genetic disorders
• infectious disease (viral or bacterial)
• the inflammatory process of the inner ear
• mal de débarquement syndrome (rare condition occurring after sustained motion)
• medication side effects
• Ménière’s disease (inner ear disorder causing episodes of vertigo)
• metabolic disorders
• musculoskeletal conditions
• neurological impairment/event/disease
• otosclerosis
• ototoxicity
• peripheral neuropathy
• persistent postural-perceptual dizziness
• psychological disorders
• space-occupying lesions of the auditory nerve
• superior semicircular canal dehiscence (a condition resulting from an opening in or thinness of the bone overlying the superior semicircular canal)
• temporal bone fracture
• traumatic brain injury
• vestibular migraine and other migraine variants (e.g., benign paroxysmal vertigo of childhood)

Pediatrics

A review of current literature indicates that the most common causes of dizziness in children are otitis media, migraine headache, benign paroxysmal vertigo of childhood, trauma, and vestibular neuritis (Gioacchini et al., 2014; O’Reilly et al., 2010). Numerous reports have detailed common disorders, illnesses, and injuries that cause vertigo and imbalance in children (Balatsouras et al., 2007; Blayney & Colman, 1984; Jahn et al., 2011; Master et al., 2020; McCaslin et al., 2011; Russell & Abu-Arafeh, 1999; Szirmai, 2010; Wiener-Vacher, 2008). Even though these reports originate from different clinics and regions of the world, there is a substantial agreement regarding the primary causes of dizziness in the pediatric population. A 2014 systematic review found the causes of vestibular disorders in children to parallel those in adults (Gioacchini et al., 2014). The authors found BPPV (19%) and migraine-associated vertigo (18%) to be the most common causes of vertigo and dizziness in children.

Roles and Responsibilities of Audiologists

Audiologists play a role in the screening, assessment, diagnosis, and management of persons with balance system disorders, often as part of an interprofessional collaborative team. Professional roles and activities in audiology include clinical and educational services (diagnosis, assessment, planning, and management); prevention and advocacy; and education, administration, and research.

Appropriate roles and responsibilities for audiologists include, but are not limited to, the following:

• Maintaining general knowledge of anatomy, physiology, and pathophysiology of the balance system, including the peripheral and central vestibular, visual, and somatosensory systems as well as interactions among these systems.
• Maintaining general medical knowledge of various conditions and events that may affect the balance system.
• Conducting calibration and function checks on equipment associated with the assessment and management of patients with dizziness and/or balance disorders.
• Participating in multidisciplinary team consultation for the assessment and management of patients with dizziness and/or balance disorders.
• Administering and appropriately altering vestibular test protocols for diagnostic and rehabilitative assessment of dizziness and/or balance disorders (e.g., electrocochleography, videonystagmography [VNG]/electronystagmography [ENG] test batteries, rotary chair testing, posturography, video head impulse test [vHIT], and vestibular evoked myogenic potential [VEMP]).
• Utilizing various patient-report tools to determine the functional impact of dizziness and/or balance disorders.
• Interpreting and integrating vestibular and balance test results and related data to establish baseline function to be used for outcome measures in future rehabilitation and/or management.
• Identifying the presence of benign paroxysmal positional vertigo (BPPV; posterior, lateral, and anterior semicircular canal variants) with clinical assessment of symptom-provoking maneuvers.
• Maintaining knowledge of procedures necessary to distinguish among posterior, lateral, and anterior semicircular canal BPPV and to distinguish between canalithiasis and cupulolithiasis.
• Maintaining familiarity with and understanding of general management options for dizziness and balance disorders (e.g., medical, surgical).
• Determining patient candidacy for vestibular and balance rehabilitation based on the integration of information from patient history, test results, functional assessment, and collaboration with other professionals.
• Maintaining knowledge of and familiarity with general medical conditions to assess their impact on or contraindication of the assessment and management of balance disorders.
• Performing canalith repositioning procedures on patients with BPPV of posterior, lateral, or anterior semicircular canal origin.
• Making referrals as appropriate.
• Accurately documenting all information collected from the patient, tests performed, results and recommendations stemming from assessment and/or management of the patient, and patient condition during all stages of assessment and/or management (including any adverse reactions).
• Consulting on the design of an individualized vestibular rehabilitation program.
• Developing and using outcome measures to determine the efficacy of vestibular rehabilitation provided.
• Providing education to patients, their families, and other care team members (e.g., teachers, and other specialists) regarding the diagnosis and functional impacts of balance system disorders.

Roles and Responsibilities of Speech-Language Pathologists

Speech-language pathologists may encounter individuals with complaints of dizziness and/or imbalance within the populations they serve.

Appropriate roles and responsibilities for speech-language pathologists include but are not limited to, providing referrals for patients who complain of dizziness and/or balance disorders.

The assessment of a patient with dizziness and/or imbalance complaints includes aspects of the central and peripheral vestibular system as well as sensory and motor balance components. Balance system assessment is an interprofessional endeavor, with audiologists serving as experts in hearing and vestibular function testing. Balance system evaluation by an audiologist may be prompted by results of a case history and/or a medical referral.

The process (whether in a screening or a comprehensive assessment) always begins with a thorough case history.

Case History

Case history information may indicate a need for modification of screening or evaluation procedures. Because the term “dizziness” can describe varying symptoms and each patient may have a different idea of what dizziness means, a thorough case history is vital (Dye, 2008).

A case history specific to balance may include the following:

• Collection of results from other health professionals.
• Fall risk information (number of previous falls, gait patterns, mentation, reaction time, vision).
• Medical history, including
  • general health (e.g., blood pressure and other vitals);
  • history of hearing loss;
  • history of dizziness, balance problems, or falls;
  • medication use (prescriptions and/or over-the-counter medications);
  • complementary and alternative medicine use; and
  • presence of comorbidities.
• Nature of dizziness and/or imbalance symptoms, including
  • aggravating factors (e.g., motion, positional, diet);
  • alleviating factors;
  • associated symptoms (e.g., auditory [hearing loss, tinnitus, aural fullness]; neurological [headache, numbness/tingling of the face, diplopia, dysarthria, dysphagia, oscillopsia, photophobia, visual aura]);
  • duration (seconds, minutes, hours, days);
  • frequency;
  • initial onset;
  • pattern (time of day, activity, symptomatic); and
  • quality and character (spinning, imbalance, disorientation).
• Patient and/or family questionnaire(s) on dizziness and the impact of balance problems on quality of life and activities of daily living.

Pediatric case histories may differ in the type of information gathered as well as the strategies used to obtain the information. Documenting the age that developmental milestones are reached and making note of a child’s performance on gross and fine motor tasks are important. Children who are deaf or hard of hearing may exhibit certain predictive factors of a co-occurring vestibular loss (Janky et al., 2018). Information regarding these factors can be used to identify children who may benefit from an age-appropriate vestibular evaluation.

Vestibular and Balance Screening

Performing appropriate screening measures may determine the need for further assessment, referrals, and/or a management plan. Screening a patient with balance complaints may assist in triaging, ruling out emergencies, and determining the probability of a central (brain/brainstem) versus a peripheral (vestibular labyrinth, eighth cranial nerve) origin. Vestibular and balance screening may be performed by audiologists as well as other trained medical professionals. Some screening measures may be affected by the patient’s understanding of the task(s), their eye muscle function and visual acuity, and their current levels of fatigue and attention.

Screening of vestibular function and vestibular ocular reflexes (VORs) may be completed at a patient’s bedside or in an office setting with little or no equipment. Normal VOR responses allow for clear vision during head and/or eye movement.

A vestibular and balance screening battery may include the following:

Observation of Nystagmus

Reflexive eye movements in response to head movement and position involve input from peripheral vestibular organs. These organs include the semicircular canals (horizontal, anterior, and posterior) and the otolith organs (utricle and saccule). Nystagmus is a reflexive eye movement characterized by two components: the slow phase, in which the eyes drift away from the center, and the fast phase, in which the eyes quickly move back toward the center. Nystagmus can be observed under various conditions (normal [physiologic] and abnormal [pathophysiologic]), which are named accordingly: spontaneous, positional, evoked, congenital, and gaze. Some level of spontaneous nystagmus may be seen in healthy individuals (Levo et al., 2004).

The presence and direction of nystagmus as well as the response to visual fixation may provide important information for differentiating between a peripheral and a central etiology of vertigo. In general, “nystagmus of peripheral origin is horizontal, and direction fixed . . . and decreases with visual fixation . . . Central signs include direction-changing nystagmus, pure vertical or torsional nystagmus and/or enhancement with fixation” (Slattery et al., 2011, p. 145).

A screening of nystagmus may include non-instrumented tests, such as direct observation using a penlight or otoscope light. The specificity of these findings will likely be reduced in comparison to those obtained with instrumented measures, such as videonystagmography (VNG) or electronystagmography (ENG; Guidetti et al., 2006).

Nystagmus can be observed using both static and dynamic measures. An example of a dynamic measure is the head-shake test. During the head-shake test, the patient tilts their head down slightly, and then, the patient or examiner shakes the head quickly back and forth for 30 s (often with fixation removed), after which the eyes are examined for the presence or absence of nystagmus. The presence of head-shake nystagmus may indicate asymmetric peripheral vestibular function (e.g., semicircular canal function).

Head Thrust Test/Head Impulse Test

The head thrust test or head impulse test assesses the VOR. It involves observing whether the patient can maintain visual fixation on a target after brief and rapid head thrusts in the planes of the semicircular canals or whether the patient requires corrective eye movements to regain eye contact with the target, which may indicate asymmetric semicircular canal function. Results of this test, taken in context, may indicate abnormal peripheral function versus abnormal central nervous system function.

Dynamic Visual Acuity Test

The dynamic visual acuity test assesses the VOR by having the patient read a Snellen eye chart first in a static position and then while the head is rotated back and forth. The lowest line on the eye chart where 50% of the characters are correctly identified may be used to compare static versus dynamic visual acuity results. The possibility of a VOR deficit depends on how many lines are lost in this comparison. The difference between static and dynamic visual acuity may indicate peripheral vestibular loss as related to gaze stabilization. Computerized systems are also available for the measurement of dynamic visual acuity.

Ocular Motility

Voluntary and reflexive eye movements can include saccadic tracking (shift in gaze from one point to another) and smooth pursuit (following a slowly moving target across the visual field). If a patient shows significant abnormalities in these functions, they may require a referral to neurology or neuro-ophthalmology for assessment of central nervous system function.

Dix–Hallpike Maneuver

This specific positioning maneuver is often used to observe nystagmus and/or vertigo associated with benign paroxysmal positional vertigo (BPPV). The patient is moved somewhat briskly from sitting to supine position with their head hanging below their shoulders and turned 30°–45° to the left or right (Dix & Hallpike, 1952). After the maneuver, the examiner observes whether nystagmus is present and, if so, notes the duration and direction of nystagmus. They also consider whether nystagmus intensity is reduced with repeated maneuvers. Abnormal results may indicate the need for canalith repositioning procedures.

Screening for Differentiation of Acute Stroke

One screening objective is to differentiate between peripheral causes (e.g., vestibular neuritis) and central causes (e.g., acute cerebellar stroke) when a patient presents with acute vestibular syndrome—a term used to describe the presence of “severe vertigo, nausea and vomiting, spontaneous nystagmus, and postural instability” (Hotson & Baloh, 1998, p. 680). One review of the literature (1966–1996) determined that etiologies for dizziness included 35%–55% peripheral vestibulopathvestibulopathychiatric disorders, 5% cerebrovascular disease, and less than 1% brain tumor, while also noting that the symptom of dizziness can be multifactorial (Hoffman et al., 1999).

HINTS, which can be helpful in this differentiation, is a three-step oculomotor/VOR test protocol that includes (a) the Head Impulse test, (b) interpretation of Nystagmus, and (c) Test of Skew (Kattah et al., 2009). Skew deviation is a vertical misalignment of the eyes that can be tested by covering the patient’s eyes, one at a time, while they focus on a fixed target.

Screening Considerations

When screening for dizziness and/or imbalance, the following considerations are important:

• Screening measures may be accompanied by postural and/or gait observations or tools such as the Romberg test and the Fukuda stepping test.
• To rule out orthostatic hypotension, you can measure the patient’s blood pressure after they have been lying down for several minutes (while they are still supine) and then again after they quickly stand up.
• Some assessment techniques for vestibular function that require equipment or instrumentation may also be considered bedside-appropriate if the clinician has access to the technology (e.g., Frenzel glasses, VNG, video head impulse test [vHIT], vestibular evoked myogenic potential [VEMP]).
• Sensitivity and specificity of bedside vestibular screening measures will vary (Cohen et al., 2014; Herdman et al., 1998; Jacobson et al., 1990; Kattah et al., 2009; Zamysłowska-Szmytke et al., 2015), whether taken individually or collectively.
• Screening tests in combination may provide more specific results; however, interpretation of findings by the examiner requires in-depth knowledge and understanding.

Comprehensive Assessment

Accurate differential diagnosis of balance system disorders relies partly on the audiologist’s interpretation of a test battery within the context of the individual’s medical history. Comprehensive assessment of dizziness and/or balance complaints will include a case history (as outlined above), results from any number of screening tests (described above), as well as an audiologic asaudiologicalin-depth vestibular assessments (described below), and information from outside referrals or sources (as part of an interprofessional collaborative team).

Audiometry

Comprehensive assessment of a patient with dizziness, vertigo, or imbalance includes an audiometric assessment. There is a close relationship between hearing and balance in relation to inner ear organs. Some patients with dizziness and imbalance symptoms will have coexisting auditory symptoms. For example, the combination of vertigo and audiologic symptoms is a classic presentation in a patient with labyrinthitis and may also be seen in patients after they experience head trauma. Audiologic assessment can provide information about possible retrocochlear or middle ear pathologies that may need to be addressed prior to further vestibular testing and follow-up.

Audiometric assessment in a patient with dizziness, vertigo, or imbalance complaints may include, but not be limited to,

• auditory brainstem response,
• electrocochleography,
• immittance testing,
• otoacoustic emissions,
• otoscopy,
• pure-tone testing, and
• speech audiometry.

Balance System Testing

A comprehensive balance system evaluation will include a combination of tests. Results and combinations of results from vestibular tests require complex interpretation and can indicate various deficits. The audiologist’s goal is differential diagnosis and differentiation of unilateral versus bilateral vestibular disorders.

Depending on the age of a pediatric patient, as well as their levels of cooperation and comprehension, it may not be possible to complete a comprehensive balance function examination. However, as with pediatric hearing assessment, experts in the assessment of pediatric dizziness have the skills necessary to adjust testing methods to collect useful information regarding the status of a child’s vestibular function and overall balance.

In interprofessional practice (IPP) settings, vital signs such as blood pressure and oxygen saturation may be measured prior to patients receiving a full balance assessment (Dye, 2008). These measurements are important because symptoms of dizziness stem from a variety of etiologies and may be multifactorial.

Videonystagmography (VNG)/Electronystagmography (ENG)

VNG and ENG are techniques used to measure and record a patient’s eye movements, including nystagmus, during a variety of tasks and conditions. Both VNG and ENG include computer analysis of eye movements. ENG is a process of recording eye movement indirectly through the electrical potential difference between the front and back of the eye. Electrodes are placed around the eyes during ENG. VNG, which has become standard in balance assessment, uses infrared video technology to record eye movement.

VNG and ENG technology enables enhanced assessment and recording of nystagmus (e.g., gaze-evoked, spontaneous) and allows for measurement of nystagmus intensity and direction. Measurements of nystagmus may be taken without fixation (i.e., in complete darkness), thus minimizing the possibility that nystagmus will be suppressed by visual fixation.

VNG and ENG technology may be used when conducting oculomotor tests, positional and positioning tests, and/or caloric tests.

Oculomotor tests measure eye movement and can be useful in identifying abnormalities of the VOR and/or the presence of spontaneous nystagmus. An oculomotor test battery may include tests of the following:

• gaze maintenance on a specific target (i.e., center, left, right, up, down) while keeping the head in a primary position
• saccades, which are the voluntary and reflexive rapid eye movements of varying amplitude that abruptly change a point of fixation and are used to bring a target object into the center line of sight
• smooth pursuit tracking of a moving object (i.e., following a target with the eyes) while the head remains still or of a stationary object (i.e., keeping eyes on a target) while the head is moving slowly
• optokinetic nystagmus, which is the normal reflexive response of the eyes when confronted with large-scale movement in the visual field

Static and dynamic position tests are used to observe the vestibular system response to a change in head and/or body position as compared with neutral head and/or body position. Measurements can be taken with or without fixation. The examiner considers the presence or absence of nystagmus and/or changes in nystagmus as well as the patient’s subjective report of symptoms.

Positional tests are most often used to elicit signs and symptoms of BPPV and to aid in diagnosing this disorder. The Dix–Hallpike maneuver is one positional test that can be used, depending on the characteristics of the patient and determination of risk factors. Symptoms of BPPV occur when otoconia moves into one of the semicircular canals. Movement of a patient from one position to another elicits or exacerbates these symptoms.

Caloric tests stimulate the vestibular system in the ear by creating a temperature difference relative to body temperature. Methods used to create a temperature change include heated or cooled air introduced into the ear canal, heated or cooled water introduced directly into the ear canal (open-loop), and heated or cooled water introduced into the ear canal inside of a balloon (closed-loop). Only a few closed-loop systems are still used in clinical practice. Testing typically includes presenting either cool and warm air or cool and warm water into each ear canal in succession. The examiner measures the presence, strength, and direction of any nystagmus that exists during and following the introduction of each stimulus. This technique allows the examiner to evaluate each labyrinth independently by comparing the strength of nystagmus that results from stimulating the left and right sides. Fitzgerald and Hallpike (1942) provided a description of one widely used caloric technique.

Considerations with caloric testing include the following:

• Responses to cool and warm stimuli will differ. Warm irrigations produce an excitatory response that causes the fast phase of nystagmus to beat toward the stimulated ear. Cool irrigations produce an inhibitory response that causes the fast phase of nystagmus to beat away from the stimulated ear.
• Providing appropriate alerting tasks to distract the patient during caloric testing is important so that the resulting nystagmus is not affected by central suppression. Formby et al. (1992) provided a comparison and ranking of several different alerting tasks used during observation of caloric-induced nystagmus.
• When standard procedures for caloric testing do not elicit a response in an individual, ice water caloric testing may be introduced as appropriate.
• Visual fixation can be assessed following the response to caloric stimulation and should reduce the intensity of nystagmus. Failure of fixation suppression may indicate a central deficit.
• Some patients will not tolerate caloric testing.
• Open-loop water irrigation is contraindicated if the patient has a perforated tympanic membrane or has pressure-equalizing tubes in place.
• Caloric testing should not be performed on any patient with cerumen obstruction of either or both ear canals.
• Caution should be used when performing and/or interpreting caloric responses on patients with a history of ear surgery in which the anatomy of the temporal bone has been altered (e.g., mastoidectomy).

Other tests that can be included in a VNG or an ENG battery are hyperventilation testing, vibration testing, and head-shake testing:

• Hyperventilation testing requires the patient to take deep, rapid breaths for 30–60 s. The examiner observes any nystagmus during this state of hyperventilation and then observes any changes in the presence or intensity of nystagmus after hyperventilation concludes.
• Vibration testing involves placing a handheld vibrating instrument on the left and right mastoid bone and on the left and right posterior sternocleidomastoid muscle (SCM) and then observing changes in the presence or intensity of nystagmus. The results may be abnormal in patients with superior semicircular canal dehiscence or unilateral vestibular hypofunction.
• Head-shake testing involves the patient tilting their head down slightly and then the patient or examiner shaking the head quickly back and forth for 30 s (often with fixation removed), after which the eyes are examined for the presence or absence of nystagmus. Presence of head-shake nystagmus may indicate asymmetric peripheral vestibular function (e.g., semicircular canal function).

Rotary Chair Testing

Rotary chair testing can be helpful in detecting bilateral and uncompensated unilateral vestibular disorders. Results may be more accurate when used in conjunction with VNG or ENG. Testing involves whole-body rotation, with the patient seated and restrained in a motorized rotary chair. Eye movements are recorded in darkness using electrodes, as in ENG, or video-oculography goggles, as in VNG. The patient’s head is properly secured so that the chair and head movements correspond. It is important to record baseline spontaneous nystagmus and gaze nystagmus prior to rotary chair testing. A rotary chair test battery may include sinusoidal harmonic acceleration tests, visual–vestibular interaction tests (i.e., visual–vestibular ocular reflex and visual–vestibular fixation), and step velocity tests, as follows:

• Sinusoidal harmonic acceleration testing involves rotating or oscillating the patient in alternating directions, rightward (clockwise) and leftward (counterclockwise), at varying harmonic frequencies. Measurements of gain (eye movement in relation to head movement), phase (timing relationship between eye movement and head movement), and symmetry (nystagmus from rightward vs. leftward rotations) are derived from the eye movement recordings.
• Visual–vestibular interaction tests assess whether the addition of visual cues results in changes of VOR gain.
  • Visual–vestibular ocular reflex testing involves the patient viewing objects on the wall as the chair turns rightward and leftward. This typically results in an increase in VOR gain compared with VOR gain measured in darkness.
  • Visual–vestibular fixation or suppression testing involves the patient fixating on a visual target that moves along with the rotary chair. This typically results in a decrease in VOR gain compared with VOR gain measured in darkness.
• Step velocity testing involves (a) rapid acceleration of the chair in one direction, (b) rotation at a constant speed for about 1 min, and (c) abrupt deceleration of the chair. The examiner measures the time it takes for the nystagmus to decay in each direction of rotation or the peak nystagmus response.

Rotary chair testing assesses both ears simultaneously, rather than independently. A natural stimulus allows for VOR measurements to be taken during physiologically relevant stimulation (i.e., head rotation) at a variety of frequencies. Rotational testing provides important information about residual vestibular function in individuals with bilateral vestibular weakness on caloric testing. This information is critical in selecting appropriate rehabilitative strategies.

Computerized Dynamic Posturography (CDP)

CDP is a method of assessing an individual’s functional balance and the contribution of visual, vestibular, and somatosensory inputs. CDP does not provide information regarding possible location of lesion or possible etiology of balance disorders. Equipment required for CDP includes a movable support surface (a force platform) within a movable enclosure.

Subtests include the following:

• The Sensory Organization Test involves measuring an individual’s postural stability or sway under varied circumstances, such as stable support surface versus moving support surface and with eyes open versus with eyes closed. On the basis of postural control performance in each circumstance, a pattern is generated, which can be associated with functional impairments. Reduced performance scores on the sensory organization test have been documented in individuals with a history of multiple falls as compared with individuals with a history of one or no falls (Whitney et al., 2006).
• The Motor Control Test involves disturbing the individual’s postural control with unexpected linear movements of the support surface and then observing and measuring their response to and recovery from these disturbances. This measure of sensory input and motor output is important in interpreting the sensory organization test as well as predicting future falls.
• The Adaptation Test involves unpredictable movement of the support surface in either the toes-up or the toes-down position, which is meant to simulate irregular walking surfaces. The individual’s ability to reduce sway and overcome instability is assessed.

Vestibular Evoked Myogenic Potential (VEMP)

VEMP offers an electrophysiological method of testing otolith (saccule and utricle) function and potentially both branches of the vestibular nerve. VEMP testing involves measuring a motor response to sound stimulation of the otolith organs.

There are two types of VEMP testing. The cervical VEMP (cVEMP) measures a relaxation response in the SCM coincident with presentation of sound or vibration. Electrodes are placed in a specified configuration on the SCM and on the forehead. Because the cVEMP is a relaxation response, the SCM must be activated (contracted) either unilaterally or bilaterally through intentional head positioning by the patient. The ocular VEMP (oVEMP) uses electrode placement under the eyes and on the forehead and measures an activation response from those muscles. For both types of VEMP testing, clicks and/or tone bursts are introduced via earphones or a bone-conduction oscillator. Recordings of waveforms are taken, and asymmetries can be identified between responses generated by stimulating the right and left ears.

Results of VEMP testing may provide insight into pathologies that affect balance and/or cause dizziness, such as superior semicircular canal dehiscence and vestibular neuritis. The use of one of these tests as opposed to the other (i.e., oVEMP or cVEMP) may be preferred for certain patients and/or situations. As with any vestibular test, VEMP results must be interpreted by a knowledgeable clinician and in the context of the patient’s personal history and characteristics. For example, patient age may impact VEMP results (Janky & Shepard, 2009; Ochi & Ohashi, 2003).

In addition to VEMP testing, other tests are available to measure otolith function. The subjective visual vertical test is one in which a patient is asked to adjust an illuminated straight line against a featureless background until it appears to be completely vertical to them. Abnormalities in this test may reflect the presence of vestibular (otolith) dysfunction.

Video Head Impulse Test (vHIT)

The vHIT is an instrumented version of the head impulse test using infrared video recording of eye movements in response to short, brisk head turns or impulses in the planes of the semicircular canals. This allows for objective measurement of eye movements rather than subjective clinician observations. The vHIT also enables evaluation of each semicircular canal independently (Hougaard & Abrahamsen, 2019). The patient is instructed to maintain visual contact on a stationary target during head impulses. Eye movements are analyzed to determine whether the eyes (a) moved in the same direction as the head during impulses and then made a corrective refixation back to the target (abnormal) or (b) moved in the opposite direction of the head during impulses and maintained fixation on the target (normal). Results may demonstrate a problem with semicircular canal function on the same side to which the head was turned prior to the corrective refixation response. This procedure is noninvasive, is relatively short, and utilizes stimuli in the physiological range of everyday head movement.

Outside Referrals/Interprofessional Practice (IPP)

IPP occurs when two or more professions collaborate with each other to improve health outcomes for a patient. This approach is vital in the assessment and management of balance and vestibular disorders. In addition to tests and services offered by a trained audiologist, the patient may require input from other medical professionals both to complete a comprehensive evaluation and to conduct management planning. For example, the patient may require medical imaging studies, a gait assessment by a vestibular physical therapist, or a review of medications by their primary care physician.

Management of balance and vestibular disorders may include medical, surgical, and/or rehabilitative approaches. Interprofessional collaborative practice is a vital part of the management process. Coordination and communication between and among balance professionals will assist the patient in achieving the best outcomes. Involved professionals may include an audiologist, a physical and/or an occupational therapist with balance expertise, a primary care physician, an otolaryngologist, a neurologist, and other medical professionals.

Medical Management

Depending on the etiology of the patient’s vestibular disorder and/or the underlying cause(s) of their balance symptoms, a variety of medical and surgical options may be recommended by appropriate medical professionals. Medications may be provided to suppress the vestibular symptoms or to treat the underlying pathology (e.g., migraine, multiple sclerosis). Dietary and/or lifestyle changes may be suggested. Surgical intervention may be considered in specific cases (e.g., excision of vestibular schwannoma [benign tumor]).

Vestibular Management and Rehabilitation

Vestibular and balance rehabilitation therapy involves activities specific to the diagnosis and individual needs of each patient. This therapy promotes the central nervous system’s natural compensation process to reduce or eliminate problematic symptoms that come with chronic balance disorders and/or dizziness.

Goals of vestibular rehabilitation may include

• promoting the compensation process of the central vestibular system,
• reducing the patient’s sensitivity to symptom-provoking movements or visual motion,
• reducing fall risk by improving static and dynamic balance and gait,
• maintaining the compensation process, and
• improving the patient’s quality of life.

Adaptation/Gaze Stabilization Exercises

Adaptation exercises target the vestibular ocular reflexes (VORs) and involve the patient performing specific head movements while keeping a visual target in focus. The clinician carefully monitors the patient’s performance for accuracy and for appropriateness of progression in difficulty. Variations are made to patient positioning, distance from target, and speed of movement. A typical adaptation exercise program may last between 6 and 8 weeks (Dye, 2008).

Habituation Exercises

The goal of habituation exercises is long-term reduction of negative responses (e.g., dizziness) to particular stimuli (e.g., motion) by repeated exposure to those stimuli. The patient will be guided to perform specific symptom-inducing movements repeatedly. Monitored progression of habituation exercises may be appropriate for a patient who has dizziness or other vestibular symptoms caused by motion or visual field sensitivity.

Substitution Exercises

The patient learns to substitute and actively control eye movements during head movement to reduce vestibular symptoms. For example, smooth pursuit and/or corrective saccades may be used to reduce dizziness. Substitution skills can be mastered with repetitive exercises using visual targets.

Balance, Strength, and Conditioning Exercises

Balance exercises challenge the patient by removing or disturbing visual input or using uneven surfaces. These exercises can focus on static and/or dynamic balance. An exercise program focusing on balance may be appropriate for a person experiencing symptoms from general vestibular hypofunction.

In some cases, muscle weakness may be found to be a contributing factor to a patient’s balance difficulties. These patients may benefit from traditional strength and conditioning exercises. This aspect of vestibular rehabilitation will require input and collaboration with a physical and/or an occupational therapist.

Functional Activities

In addition to exercise programs, the balance management team also considers the patient’s functional performance. For example, an occupational therapist may do a home assessment to ensure that fall risk is reduced, a physical therapist may recommend gait activities, or an audiologist may provide education on how specific vestibular and balance disorders can impact a person’s daily activities.

Canalith Repositioning Procedures

Canalith repositioning procedures (CRPs) are maneuvers used in the management of benign paroxysmal positional vertigo (BPPV). BPPV is caused by otoconia detaching from the utricle and/or saccule and collecting in the semicircular canals. Typical symptoms of BPPV include dizziness, vertigo, imbalance, and nausea. The goal of repositioning maneuvers is to move otoconia out of the semicircular canals to reduce dizziness and/or other vestibular symptoms. CRPs involve specific sequences of head and body movements guided by a trained professional. Eye movements are monitored during each guided head and body movement sequence.

Patients may be instructed to follow limitations and restrictions (e.g., posture, head movements, activities) for some time after the maneuver. However, use of postmaneuver restrictions generally does not improve the efficacy of the procedure or the patient outcomes (Casqueiro et al., 2008; Hunt et al., 2012; McGinnis et al., 2009; Roberts et al., 2005).

Posterior Semicircular Canal BPPV Management Maneuvers

One management option for posterior semicircular canal BPPV is the Epley maneuver, which assists in the migration of otoconia (Epley, 1992). Medication may be given to reduce nausea during the procedure.

The Semont maneuver, also called the Liberatory maneuver, manages BPPV in conditions with free-floating otoconia and with otoconia that are attached to the cupula in the posterior semicircular canal. Movements undertaken with this maneuver are done with more speed than required with the Epley maneuver.

Lateral Semicircular Canal BPPV Management Maneuvers

Techniques such as the “barbeque roll,” Lempert maneuver, and Gufoni maneuver all target the lateral semicircular canal variant of BPPV. These techniques involve variations of rotating and tilting movements performed by the patient.

Anterior Semicircular Canal BPPV Management Maneuvers

Anterior semicircular canal BPPV is rare and is sometimes diagnosed after a head injury or recovery from surgical procedures. Less information is available on effective management. In some cases, the Epley maneuver or Semont maneuver may be helpful. Another technique called prolonged forced position procedure has been described (Crevits, 2004).

Counseling and Patient Education

Each patient with dizziness and/or imbalance concerns will require education and counseling specific to the etiology, symptomology, and characteristics of their disorder. Ensuring a patient’s health literacy regarding their diagnosis and management options will allow them to make informed decisions and to be an active participant in their care. A patient with chronic balance issues can use a variety of strategies to remain active, reduce fall risk, and cope with symptoms.

Management Considerations

Pediatrics

Untreated vestibular system impairments in children can lead to problems with coordination and delays in developmental milestones (Rine et al., 2004). Once a child has had a medical evaluation by a physician (e.g., pediatrician, neurologist, otolaryngologist) and a thorough diagnostic assessment, an effective management plan can be developed. Outcome measures may include the use of tools related to dizziness-related quality of life and dizziness symptoms (McCaslin et al., 2015).

Management Limitations

Factors that may limit the success of vestibular rehabilitation include

• cerebellar dysfunction (e.g., stroke);
• cognitive deficits;
• excessive nausea;
• fluctuating etiologies (e.g., Ménière’s disease, perilymph fistula);
• mental health conditions (e.g., anxiety, depression);
• patient compliance;
• polypharmacy;
• reduced proprioception; and
• reduced vision.

Contraindications for canalith repositioning maneuvers include

• acute bone fractures,
• history of back or neck problems,
• medical conditions (e.g., unstable heart disease),
• reduced mobility or flexibility, and
• retinal detachment.

References