Bilateral vestibular hypofunction

• Bilateral vestibulopathy
• Bilateral vestibular (BVL)

• 386.54 Hypoactive labyrinth, bilateral

• H81.23 Vestibular neuronitis, bilateral

• Pattern 5A: Primary Prevention/Risk Reduction for Loss of Balance and Falling
• Pattern 5F: Impaired Peripheral Nerve Integrity and Muscle Performance Associated with Peripheral Nerve Injury

Description

• Disorder of the peripheral vestibular system (part of the inner ear)
• The peripheral vestibular system of each ear is made up of the vestibular nerve and five sensory organs (hair cell receptors contained within the superior, posterior, and horizontal semicircular canals, and also within the utricle and saccule)
• Vestibular sensory organs detect head position and head motion to provide input for gaze stability, orientation, and balance
• Reduction or loss of vestibular function of both systems causes a reduction or loss of neural input, resulting in gaze instability, disorientation, and imbalance

Essentials of Diagnosis

• Physical exam normal
• Audiogram normal
• Neurotologic exam abnormal
• Thorough, detailed history essential to distinguish bilateral vestibulopathy from other vestibular disorders or central pathology

General Considerations

• Hallmark symptom is gaze instability and imbalance
• Impairments tend to develop slowly and progressively in most cases, and tend to be more severe than those with unilateral dysfunction
• Patient complaints may be overlooked as being due to inner ear pathology because reports of vertigo are rare
• There must be pathological asymmetry of the neural activity between the two inner ears for symptoms of vertigo to occur; with bilateral vestibulopathy, neural impairment or loss is often equal between the two ears and will not create vertigo
• Patients may or may not report dizziness from head movement
• Patients do not typically report hearing loss, aural fullness, or tinnitus

Demographics

• Bilateral vestibulopathy is rare among vestibular disorders
• May account for 4% to 9% of diagnoses in clinics specialized in vestibular disorders
• Primarily occurs between ages 61 to 70 years, though can occur at any age

Signs and Symptoms

• Blurred (bouncing, jumping) vision most noticeable when moving head and walking; due to oscillopsia (apparent movement of the environment) from vestibulo-ocular reflex deficit
• Occasional complaints of vague dizziness
• Postural and gait instability when sensory input challenged
• Increased risk of falling
• Abnormal neurologic exam (impulse test, dynamic visual acuity test, caloric test)
• Usually no report of hearing loss
• No central signs (diplopia, dysarthria, dysphagia, dysmetria, numbness, weakness)

Functional Implications

• Blurred vision while reading signs when walking or driving
• Impeded balance, especially in dimly-lit environments or when ground is uneven
• Reduced or lost ability to perform tasks in home, at work, or driving

Possible Contributing Causes

• Etiology is idiopathic in half of cases
• Most common cause is ototoxic drugs (usually aminoglycoside antibiotics; antineoplastic medications, such as vincristine, vinblastine, cisplatinum; or diuretics, such ...