Vestibular Pathologies

Original Editor - Bernard Tonks Top Contributors - Jess Bell, Kim Jackson, Lucinda hampton, Rucha Gadgil, Olajumoke Ogunleye and Tarina van der Stockt

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Introduction

Vertigo is defined as the illusion of movement occurring in the environment. Acute vertigo can be caused by the following conditions:

• Cerebrovascular accident - posterior circulation strokes
• Neurological disorders - e.g. multiple sclerosis
• Endolymphatic hydrops - e.g. Meniere’s disease
• Migraine associated vertigo (also known as vestibular migraine)
• Vestibular neuritis and labyrinthitis
• Head trauma (occasionally)
• BPPV

Unilateral Vestibular Lesion (UVL)

Vestibular Neuritis and Labyrinthitis

Vestibular neuritis and labyrinthitis are categorised as unilateral vestibular lesions (UVL). Other terms used include unilateral vestibular hypofunction (UVH) or unilateral vestibular dysfunction (UVD). They are the second most common cause of vertigo. While there is little epidemiological data about labyrinthitis, vestibular neuritis occurs in approximately 15 per 100,000 people in the US.

They are believed to usually be caused by viral infections:

• In neuritis, the superior division of the eighth cranial nerve is commonly affected and hearing is preserved
• In labyrinthitis, the entire labyrinth is involved and there is hearing loss

Acute versus Chronic UVL

In acute cases of UVL, symptoms include:

• Nystagmus
• Nausea
• Vomiting
• Imbalance

Physiotherapists do not often see patients in the acute stage. In chronic cases, symptoms include persistent dizziness and imbalance due to a lack of compensation.

UVL Nystagmus

Vestibular neurons fire spontaneously at 100 AP/sec. A loss of input from one side and relative excitation of the intact side causes a mixed horizontal and torsional nystagmus. The direction of nystagmus is labelled according to the quick phase:

• A right-sided lesion causes left beating and left torsional nystagmus

There is a torsional component to the nystagmus because the superior division of the nerve (which innervates the horizontal and anterior canals) is affected.

Acute Symptoms or Vestibular Crisis

The acute stage, which usually lasts 2 to 3 days, is characterised by intense vertigo and nausea due to unequal vestibular input and disequilibrium. After a few days, acute symptoms resolve, but the patient is left with a dynamic deficit - i.e. dizziness and disequilibrium with rapid head movements. Vestibular rehabilitation plays an important role in the recovery of these dynamic deficits.

Recovery

Spontaneous Recovery

Nystagmus, skew-eye deviation and marked postural asymmetry recover spontaneously within 3 to 14 days. These are termed static deficits. This recovery of function is due to the restoration of the tonic resting firing rates of the vestibular nuclei. This is achieved through the influence of the cerebellum and neurochemical changes at the level of the vestibular nuclei.

Cellular Recovery

When there has been aminoglycoside toxicity, it has been found that cellular recovery is possible for non-primate mammals. It is not known if this recovery can occur in humans, but there is no evidence of regeneration of vestibular neurons in primates.

NB aminoglycosides are powerful broad-spectrum antibiotics that can adversely affect the kidney (nephrotoxicity), vestibular and auditory organs (ototoxicity), and the neuromuscular junction.

Summary of UVL

• Frequently caused by neuritis or labyrinthitis:
  • Neuritis – hearing is unaffected, vestibular impairment
  • Labyrinthitis – some loss of hearing, vestibular impairment
• There is some evidence that corticosteroids can be helpful in the acute stage if they are given within 72 hours
• Recurrence is not common
• Physiotherapists typically only see patients in the chronic phase - at this stage patients are generally functioning fairly well unless they move their heads too quickly
• Patients in the chronic phase usually present with problems in one or more of the following domains:
  • Gaze stability issues
  • Motion sensitivity
  • Compromised balance and postural control

Bilateral Vestibular Lesions (BVL)

BVLs are symmetrical and they are often due to ototoxicity, commonly related to aminoglycoside (gentamicin or streptomycin) use (see above).

• In high doses, these antibiotics consistently destroy the hair cells of the inner ear
• In normal doses, it has been found that ototoxicity occurs spontaneously in 3 percent of the population

Unlike in UVLs, vertigo occurs infrequently in these patients because the acute vestibular loss is bilateral and symmetrical. Patients with BVL primarily report:

• Balance problems during standing or walking
• Oscillopsia
• Disequilibrium and dizziness
• Physical deconditioning

Age-Related Vestibular Changes

In individuals aged over 75 years, there is, on average, a 35 percent decrease in the vestibular system’s ability to encode faster head movements. This is why older adults have more difficulty moving quickly and tend to slow down their head movements. Older individuals can, therefore, be thought of as asymmetrical BVL patients.

Perilymphatic Fistula

A perilymphatic fistula is a tear or defect in a membrane between the fluid-filled inner ear and middle ear. This causes pressure changes from the environment accessing the vestibular system and perilymphatic fluid might flow between the two compartments. Causes of perilymphatic fistula include:

• Head trauma (most common)
• Barotrauma (scuba diving, explosions)
• Vigorous straining
• Tumour in the middle ear
• Chronic severe ear infections

Patients present with:

• Ringing or fullness in the ears, vertigo, imbalance and hearing loss
• Tullio phenomenon - i.e. symptoms evoked by an auditory stimulus
• Symptoms may increase with changes in altitude or air pressure (weather), exertion and activity

The diagnosis of perilymphatic fistulas is controversial due to a lack of diagnostic tests. Medical management includes: bed rest, mild sedation and avoiding activities that could increase inner ear pressure. In severe cases, surgical grafting may be required.

Meniere’s Disease and Endolymphatic Hydrops

Meniere’s disease or primary hydrops is a disorder of the inner ear, that results in recurrent attacks of self limiting vertigo. Other associated symptoms are: unilateral fluctuating low frequency sensorineural hearing loss, a sense of ear “fullness” and tinnitus.

Meniere’s disease is idiopathic - i.e. it has no known cause.  Various theories have been proposed about the pathophysiology of Meniere’s Disease. It is possibly due to the malabsorption of endolymph in the endolymphatic sac or duct, which causes pressure fluctuations in the inner ear fluid.

Secondary hydrops is related to a specific event or condition such as head trauma, infection, degeneration, tumour.

Patients present with the following symptoms:

• Ear fullness, tinnitus, fluctuating hearing loss, vertigo and imbalance
• In time, low-frequency sensorineural hearing loss develops
• Vestibular function is episodic and the system may return to normal between episodes
• Can last hours to a few days

Treatment

• Dietary: decrease salt, alcohol, nicotine, and caffeine intake
  • This may minimise any secondary fluctuations in the endolymph of the inner ear, and accordingly may reduce a patient’s dizzy spells
• Vestibular rehabilitation (VR) does not appear to help, unless there is permanent loss of vestibular function in the later stages of the disease. However, more recently, some therapists are providing VR exercise-based treatment in an attempt to improve the final outcomes. While there is no research currently to support this, there is no harm in trying.

Other Pathologies

Trauma (Labyrinthine Concussion)

A common cause of vestibular dysfunction in a younger population. It is usually caused by direct trauma to the vestibular system, but can also occur with abrupt changes in head position not associated with impact.

Acoustic Neuroma

Patients with acoustic neuroma most likely experience unilateral hearing loss or tinnitus. A vague feeling of swaying or tilting is commonly the only manifestation of vestibular dysfunction.

Herpes Zoster Oticus

Herpes zoster oticus (also known as Ramsay Hunt Syndrome) is possibly an activation of latent herpes zoster infection in the lateral geniculate. In addition to vestibular symptoms, it often also causes facial paralysis.

Otitis Media

 An inflammation of the middle ear and the tympanic membrane, which may be associated with vestibular symptoms in  severe cases or when there are repetitive infections.

Superior Canal Dehiscence Syndrome

 A condition where the bone overlying the superior aspect of the anterior canal is thin or absent. It can also affect the posterior canal. It can cause hearing and balance issues.

Concussion / Mild Traumatic Brain Injury (mTBI)

Vestibular and ocular symptoms are common in patients who experience mTBI patients. These symptoms are typically caused by a combination of both central and peripheral conditions.For some patients, symptoms associated with acute mTBI might resolve within days. However, for other patients, symptoms might persist for months post-injury, potentially lasting for more than a year - i.e. post-concussion syndrome (PCS).

The National Collegiate Athletic Association Injury Surveillance System database (mTBI) found the following audiovestibular symptoms symptoms in athletes:

• Dizziness (68 percent)
• Balance problems (34 percent)
• Noise sensitivity (29 percent)
• Tinnitus (9 percent)

Marcus and colleagues screened major trauma ward admissions for adults and found that 87 percent of patients had subjective dizziness (i.e. the illusion of self-motion) and / or objective imbalance. Specific diagnoses given for this dizziness included:

• BPPV (38 percent)
• Acute peripheral unilateral vestibular loss (19 percent)
• Migraine phenotype headache (34 percent)

These symptoms are also common in children:

• Ellis and colleagues found that 29 percent of children had visual and ocular symptoms acutely.  Of the children who developed chronic concussive symptoms, 63 percent had visual and ocular symptoms
• Master and colleagues found that 46 percent of children had more than one visual deficit after mTBI
• Reimer and colleagues found that of 115 paediatric patients with sports related concussion, 12 children (10.4%) were diagnosed with BPPV

Vestibular dysfunction should, therefore, be considered in patients who report dizziness and unsteadiness immediately after concussion that improve gradually during the first few weeks post-injury. NB patients may report that these symptoms are provoked by rapid head movements and that blurred vision occurs with these movements (which suggests altered VOR function).

Assessment of the Vestibular System

For patients with vestibular symptoms, a vestibular assessment should include:

• Subjective history
• Vestibulo-Ocular Reflex (VOR) function
• Static and dynamic balance / postural control
• Assessment of nystagmus with and without fixation
• Positional testing for BPPV (BPPV may occur in approximately 5 to 10 percent  of cases of persistent dizziness following concussion) WEB
• Motion sensitivity
• Assess the neck and screen the vision system
• Oculomotor control
• Effects of visual motion
• Pressure sensitivity
• Infrared camera systems

Assessment of the vestibular system is discussed in more detail here. LINK next page...

Vestibular Rehabilitation

Vestibular rehabilitation (VR) may be of benefit for individuals with peripheral vestibular disorders (including BPPV), stable central vestibular disorders, concussion and post-concussion syndrome.

Vestibular rehabilitation usually includes canalith repositioning maneuvers (for BPPV) and individually targeted exercises aimed at facilitating sensorimotor compensation (including adaptation, habituation, substitution, and standing and dynamic balance exercises).

Evidence for Vestibular Rehabilitation for Post Concussion Syndrome (PCS)

More evidence is emerging to support the use of VR in patients who have PCS, particularly interventions that include psychological, cervical and vestibular rehabilitation.

• A retrospective study by Alasheen and colleagues looked at 114 patients referred for VR after concussion. Patients most commonly reported the following symptoms:
  • A sense of being off-balance (68 percent)
  • Lightheadedness (54 percent)
  • Spinning (46 percent)
  • Nausea (38 percent)
  • A sensation of motion (23 percent)
• Overall, Alasheen and colleagues found that:
  • Patients who had persistent dizziness and balance / gait dysfunction after concussion tended to improve after VR
  • Recovery occurred across a number of areas, including:
    • Dizziness Handicap Inventory
    • Activities-specific Balance Confidence
    • Functional balance performance

• Schneider and colleagues studied the impact of VR on 31 participants who had persistent symptoms of neck pain, dizziness and / or headaches post-sports related concussion:
  • 73 percent of the group receiving VR and cervical spine treatment in addition to the postural education, range of motion exercises, rest and graded returned to sport at 8 weeks compared to only 7 percent of the control group
• Brown and Camarinos found that symptoms such as headaches, dizziness, neck pain, gaze instability, balance dysfunction and fatigue can be improved with a multimodal approach that includes vestibular and cervicogenic rehabilitation, exertional training and education.

Visual-Vestibular Mismatch

Visual-vestibular mismatch refers to visual-vestibular integration / processing impairments. It is quite common in the PCS population. It may be caused by dysfunctional sensory input and / or a disruption in CNS processing / sensory integration. Often visual and / or vestibular input are affected. Anxiety can also be a powerful disruptor of sensory integration.

When a patient has a visual-vestibular mismatch, she / he might report the following:

• Has frequent headaches
• Feels unable to read, watch TV or work on computers for very long without symptoms
• Dislikes being in busy environments (e.g. shopping)
• Keeps bumping into walls/furniture
• Feels nervous when walking down the stairs
• Feel "off" a lot of the time
• Avoids going out - e.g. to the movies, out with friends, to restaurants or the theatre / concerts

Post Trauma Vision Syndrome (PTVS)

Post-trauma vision syndrome (PTVS) is characterised by binocular function problems. Signs and symptoms of PTVS include:

• Eyes drifting outward
• Eyes not working together
• Double vision
• Blurred vision
• Light sensitivity
• Functional visual field loss – testing for structural problems can be normal
• Concentration difficulties
• Symptoms provoked with reading
• Poor spatial judgement/depth perception
• Sense of visual midline is off

Evaluating mTBI and Dizziness

Evaluation of clients head and neck trauma with or without a diagnosis of concussion should include an assessment of:

• Cervical spine
• Vestibular system
• Vision system
• Sensory integration
• Anxiety

Included in this evaluation is the assessment of postural control and balance. This is discussed in more detail here. LINK