Bilateral Vestibular Hypofunction
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Description
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Bilateral vestibular hypofunction (BVH) is a heterogeneous condition that results from defects in either the vestibular organs, eighth cranial nerves, or a combination of the two.[1][2][3] This condition causes impairments in the vestibulo-ocular reflex (VOR) and the major functions of the vestibular organs. Due to the loss or diminished function, patients may present with imbalance, oscillipsia and impaired spatial orientation.[2] Depending on the cause, individuals may also present with neurological and auditory symptoms.[2] Prognosis is determined by the severity of this condition, which is dependent on the number of underlying comorbidities.[4] Individuals with initial poor falls risk scores, lower balance confidence, and greater disequilibrium tend to have poorer disability that may influence functionality in everyday life.[4]
Due to the heterogeneity of the disease, BVH has four clinical subtypes:[2][3]
- Recurrent vertigo and BVH
- Rapidly progressive BVH
- Slowly progressive BVH
- BVH with neurological deficits
Epidemiology[edit | edit source]
BVH is an uncommon condition that is frequently misdiagnosed or underdiagnosed.[3] The reported prevalence of BVH in literature ranges from 28 to 81 per 100 000 US adults, with greater prevalence seen in women and Hispanics.[2][3][5] Individuals diagnosed with BVH are more likely to present with social, physical and functional impairments and limitations.[5]
Etiology/Causes[edit | edit source]
BVH is often a secondary condition from a wide spectrum of causes as listed in Table 1 below. Majority of BVM cases, about 51%, are idiopathic in nature because an underlying cause cannot be identified.[2][3][4] Of the known determinants, toxic/metabolic (13-21% of cases) is the most common and an example of this is ototoxicity, where the side effect of antibiotics, particularly aminoglycoside, results in persisting deficits (BVH).[2][3][4] Other known causes may be the result of an infection (3.8-12%) such as meningitis, and encephalitis.[2][3][4]
Clinical Presentation[edit | edit source]
Common Symptoms of BVH:
Oscillopsia
Oscillopsia is visual blurring or oscillating of objects in an individual’s visual field while the head is in motion, and is experienced by 25-86% of patients with BVH. (van de berg, Herdman 2014) This reduces the vestibulo-ocular reflex, which is important in stabilizing gaze on stationary objects and maintain a motionless visual field as the head moves (van de berg). In BVH, this deficit results in the eyes to move along with the head creating excessive motions of objects in the visual field even if stationary, which impairs vision. (van de berg) Patients experiencing this may complain of blurred vision during movement or activities. (van de berg) Oscillopsia may increase with irregular or unpredictable head movements, such as head movements while walking. (van de berg, Herdman 2014) Inability to read street signs or identify people’s faces as they walk, or difficulty having clear sight while in a moving car may result. (Herdman 2014) If severe, patients’ postural stability could be compromised due to decreased ability to use visual cues for stability (Herdman 2014).
Imbalance
Patients with BVH typically complain of unsteadiness, imbalance, or a sense of “off-balance”, whether subtle or severe. (van de berg & Herdman 2014) Postural control and orientation depends on proprioceptive, visual, and vestibular inputs and is disrupted in BVH due to failure of the vestibulospinal reflex. (van de berg) Therefore, patients present with decreased accuracy in gravity detection, and balance impairments during activities (walking in the dark or uneven surfaces, or any high frequency head movements) have an increased risk of falling. (van de berg) Reduction in symptoms may be noticed when lying down, sitting with head support, and with avoidance of physical activities. (herdman 2014)
Visual Vertigo
Patients with BVH increase their visual dependence and use of visual inputs which may lead to visual vertigo. This is where symptoms (feeling off-balance, spinning, objects moving) are aggravated by visual contexts (moving objects, busy/crowded places, scrolling down on the computer screen, etc). (van de berg) Patients can experience abnormally large postural responses to visual environments with visual vertigo. (van de berg)
Cognitive Deficits
Difficulty concentrating, fatigue, and being in a “brain fog” are some cognitive deficits that individuals with BVH may report (van de berg). These symptoms may be the result of constant compensation, avoidance of imbalances, and attention to tasks such as walking, especially when paired with cognitive tasks (patients may stop walking if need to talk). ( van de berg) Spatial learning and memory deficits result from absent labyrinthine input. (van de berg)
Psychological or Psychiatric Symptoms
Symptoms of chronic disequilibrium and difficulty performing activities of daily living can have psychological impacts (van de berg, & Herdman 2014). Particularly in the chronic phase (3+ months), psychiatric disorders (depression, somatic anxiety, etc.) have debilitating effects on the clinical picture and prognosis, therefore it is important healthcare providers take this into consideration when assessing and treating patients with BVH. (van de berg)
Neurological Symptoms
As stated in Table 1: Etiology of BVH, BVH may be caused by neurological diseases (spinocerebellar ataxia, multiple system atrophy, etc.), infectious diseases (meningitis, encephalitis, etc.), vascular lesions, and other neurological conditions. (van de berg, Lucieer) Up to 39% of patients with BHV may have vestibular deficits combined with a neurological disorder. (van de berg)
Autonomic Symptoms
The vestibulosympathetic reflex projects to areas involved in regulation of emotional aspects of vestibuloautonomic function, and cardiorespiratory activity (breathing, heart rate and blood pressure) (van de berg). As such, orthostatic hypotension or autonomic symptoms may be the consequence of a disturbance between vertigo and panic (van de berg).
Clinical pictures of the four different clinical subtypes: (van de berg, lucieer)
1. Recurrent vertigo and BVH
Patients experience episodic vertigo that may persist for several years and bilateral vestibular function loss symptoms. (van de berg, lucieer)
2. Rapidly progressive BVH
Rapid progression or sudden onset of BVH symptoms with or without episodes of vertigo. (van de berg, lucieer)
3. Slowly progressive BVH
Gradual development of symptoms, mainly without episodic vertigo. (van de berg, lucieer)
4. BVH with neurological deficits
Combination of BVH and neurological symptoms, such as peripheral polyneuropathy and/or cerebellar ataxia. (van de berg, lucieer)
These four subtypes show broad clinical pictures and demonstrates that vertigo does not always have to be a symptom of BVH. (van de berg) Depending on patient symptoms (vertigo or hearing loss), medical assistance can be required early on in onset, however if subtle or episodic in nature can lead to the delay in diagnosing this condition. (van de berg, lucieer)
Diagnostic Procedures [edit | edit source]
Currently, there is no standardized procedure implemented for diagnosing BVH by healthcare professionals due to the challenges faced with diagnosing, as patients present with a broad spectrum of signs and symptoms.[2][3][6] However, symptoms specific to, and commonly reported by patients include ; oscillopsia (strong indicator of BVH), unsteadiness, episodic and spontaneous vertigo.[6]
Vestibular tests performed to help diagnose BVH:[2][3]
- Caloric Test
- Rotatory Chair Test
- Head Impulse Test (HIT)
- Vesitbular-Evoked Myogenic Potentials (VEMP)
- Dynamic Visual Acuity Test (DVA)
- Torsion Swing Test
Other tests conducted to aid in determining the cause:[2]
- Cerebral imaging
- Audiometry
- Blood Tests
Medical Management
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Management of patients in the acute phase involves the use of vestibular suppressants and anti-emetics.[7] However, currently the use of medications for chronic BVH is not supported by evidence.[7]
Physiotherapy Management/Intervention[edit | edit source]
The management guidelines for patients with BVH varies according to the stage of the disorder. The original exercises developed by Cawthorne and Cooksey in the 1940’s outlined a general approach to vestibular rehab, which included a standardized series of exercises that involve eye movements without moving the head, head movements with eyes open or closed, bending over, sit-stand, tossing a ball and walking.[8]
Outcome Measures [edit | edit source]
Outcome measures are based on the International Classification of Function Model.[1][9]
Common outcome measures influencing the Body Structure and Function level:[1][10]
- Dynamic Visual Acuity Test (Level 3 = recommended)
- Sensory Organization Testing
- Dynamic Posturography
Common measures determining one’s ability to execute tasks in the Activities Classification level:[10][9][11]
- Berg Balance Scale (Level 2 = reasonable to recommend)
- Dynamic Gait Index
- Timed Up and Go
Measures that help determine participation in society:[1][9]
- The Activities-Specific Balance Scale (level 2)
- Dizziness Handicap Inventory (Level 4 = Highly recommended)
- Other measures for Quality of Life such as the Vestibular Disorder Activities of Daily Living
Additional outcome measures for Body Structure and Function:[9]
- Gait Stabilization Test
- Sharpened Romburg
- Sensory Organization Test with Head Shake, (Modified) Clinical Test of Sensory Interaction on Balance
- Visual Analogue Scale
- Visual Vertigo Analogue Scale
- Motion Sensitivity Quotient, and/or Vertigo Symptoms Scale
Additional outcome measures for Activity/Participation:[9]
- Five Times Sit-to-Stand
- 30-Second Chair Stand
- Functional Reach/Modified Functional Reach
- Gait Velocity (10m Walk Test)
- Balance Evaluations Systems Test
- Mini Balance Evaluation Systems Test
- Modified Timed Up and Go with Dual Task
- Disability Rating Scale
- UCLA Dizziness Questionnaire
- Vertigo Handicap Questionnaire
- Vestibular Handicap Questionnaire
- Vestibular Activities and Participation
- Vestibular Rehabilitation Benefit Questionnaire
Resources
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Additional information can be found on https://vestibular.org/BVH
Clinical Practice Guideline can be found on https://vestibular.org/sites/default/files/Cynthia/Vestibular%20Rehab%20CPG%20JNPT%202016.pdf
Outcome measure reviews can be found on http://www.neuropt.org/professional-resources/neurology-section-outcome-measures-recommendations/vestibular-disorders.
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References[edit | edit source]
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- ↑ 1.0 1.1 1.2 1.3 Porciuncula F, Johnson CC, Glickman LB. The effect of vestibular rehabilitation on adults with bilateral vestibular hypofunction: a systematic review. Journal of Vestibular Research. 2012 Jan 1;22(5, 6):283-98.
- ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 Lucieer F, Vonk P, Guinand N, Stokroos R, Kingma H, van de Berg R. Bilateral vestibular hypofunction: insights in etiologies, clinical subtypes, and diagnostics. Frontiers in neurology. 2016;7.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 van de Berg R, van Tilburg M, Kingma H. Bilateral vestibular hypofunction: challenges in establishing the diagnosis in adults. ORL. 2015 Sep 15;77(4):197-218.
- ↑ 4.0 4.1 4.2 4.3 4.4 Herdman SJ. Bilateral Vestibular Hypofunction.
- ↑ 5.0 5.1 Ward BK, Agrawal Y, Hoffman HJ, Carey JP, Della Santina CC. Prevalence and impact of bilateral vestibular hypofunction: results from the 2008 US National Health Interview Survey. JAMA Otolaryngology–Head & Neck Surgery. 2013 Aug 1;139(8):803-10.
- ↑ 6.0 6.1 Telian SA, Shepard NT, Smith-Wheelock M, Hoberg M. Bilateral vestibular paresis: diagnosis and treatment. Otolaryngology—Head and Neck Surgery. 1991 Jan;104(1):67-71.
- ↑ 7.0 7.1 Horak FB, Jones-Rycewicz C, Black FO, Shumway-Cook A. Effects of vestibular rehabilitation on dizziness and imbalance. Otolaryngol Head Neck Surg. 1992;106(2):175-180.
- ↑ Cawthorne T. Vestibular injuries. Proc R Soc Med. 1946;39(5): 270-273
- ↑ 9.0 9.1 9.2 9.3 9.4 Hall CD, Herdman SJ, Whitney SL, Cass SP, Clendaniel RA, Fife TD, Furman JM, Getchius TS, Goebel JA, Shepard NT, Woodhouse SN. Vestibular rehabilitation for peripheral vestibular hypofunction: an evidence-based clinical practice guideline: from the American physical therapy association neurology section. Journal of Neurologic Physical Therapy. 2016 Apr;40(2):124.
- ↑ 10.0 10.1 Brown KE, Whitney SL, Wrisley DM, Furman JM. Physical therapy outcomes for persons with bilateral vestibular loss. The Laryngoscope. 2001 Oct 1;111(10):1812-7.
- ↑ Whitney S, Wrisley D, Furman J. Concurrent validity of the Berg Balance Scale and the Dynamic Gait Index in people with vestibular dysfunction. Physiotherapy Research International. 2003 Nov 1;8(4):178-86.
