VERTIGO
Definition:
Vertigo refers to a specific symptom describing a false sense of motion, usually spinning or rotatory, in the surroundings or within oneself despite the absence of physical movement. In clinical practice, the term ‘vertigo’ is not usually volunteered by patients.
Causes:
The labyrinth is an inner ear neurosensory organ made up of two components – Semicircular canals (for balance) and Cochlear (for hearing).
Typically, vertigo is caused by an imbalance of sensory inputs into the two vestibular nuclei from over activity or underactivity of either or both sides of the labyrinth. The brain interprets such input differences as a sensation of movement. However, any disturbances to the labyrinth, visual-vestibular interaction centers in the brain stem and cerebellum, and sensory pathways to or from the thalamus, can result in vertigo.
Causes of vertigo are divided into central or peripheral origins:
In the general practice setting, the three most common causes of vertigo (accounting for 93% of all patient presentations) are:
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- Benign paroxysmal positional vertigo (BPPV).
- Acute peripheral vestibulopathy (vestibular neuritis or labyrinthitis).
- Meniere disease.
Examination-
- A detailed examination of the patient starts with a general inspection looking for patterns of facial asymmetry suggesting either peripheral facial nerve involvement or a cerebrovascular event.
- The vesicles of herpes zoster on the external ear might also be visible.
- Otoscopic examination may reveal signs of inflammation associated with acute vestibulopathy, scarring of the eardrum from chronic suppurative otitis media, or an erosive cholesteatoma.
- The Hennebert sign is positive when the symptom of vertigo is reproduced by applying external pressure on the tragus. The positive sign suggests the presence of a perilymphatic fistula.
- Careful observation for features of nystagmus such as spontaneity, direction, and associated changes with eye movements, convey valuable diagnostic information. The direction of the nystagmus is determined by the ‘fast phase’ of the eye movement. Horizontal and torsional nystagmus, which beats to a unilateral direction regardless of whether the eyes are gazing to the left or right, suggests the vertigo is of peripheral origin. Conversely, if the direction of nystagmus changes when the eyes are gazing toward a different direction, a central cause of vertigo is more likely. Vertical nystagmus also implies central and brainstem involvement.
- The head impulse test is both sensitive and specific to detect unilateral hypofunction of the peripheral vestibular system, which is commonly due to acute vestibulopathy.
- Usually, a functional vestibular system can detect small changes in the head position and rapidly adjust eye movements so the centre of vision remains on a target.
- In patients with acute vestibulopathy, when the head is turned toward the affected side there will be a delay in vestibular adjustment. Such a delay will manifest as a brief and fixed gaze toward the affected side followed by a corrective saccadic eye movement back to the centre.
- One important role of the head impulse test is to differentiate between cerebellar infarction and acute vestibular neuritis. In patients with acute vertigo but a normal head impulse test, acute vestibulopathy is ruled out and cerebrovascular causes of vertigo such as ischaemia or infarction should be considered.
- A Romberg test assesses the integrity of peripheral proprioception, cerebellar and vestibular functions.
- A Romberg test is positive when the patient can maintain their balance with both feet placed close together with visual input, but not when the eyes are closed.
The Fukuda-Unterberger test–
- In the Fukuda-Unterberger test, the patient is asked to march on the spot with their eyes closed.
- The test is positive when the patient deviates from the midline; usually toward the side with a relatively lower vestibular activity.
The Dix-Hallpike manoeuvre-
- The Dix-Hallpike manoeuvre should be performed if the history is suggestive of BPPV or if the nystagmus is inducible.
- Steps for Dix-Hallpike manoeuvre-
If symptoms are more suggestive of central vertigo, a thorough neurological examination should be performed. Signs of cerebellar dysfunctions such as dysdiadochokinesia, dysmetria, dysarthria and ataxia should also be sought. Cardiovascular examination and testing for postural hypotension can also provide useful clues.
Investigation
- Audiological testing can check for the presence of hearing loss and quantify it. Bilateral low frequency sensorineural or conductive hearing loss is typical of Meniere disease.
- Caloric testing evaluates the vestibular labyrinth function; however, this test should only be done in a specialist centre and the results interpreted by a clinician with expertise in the field.
- Neuroimaging is an important investigative tool if there is a concern of a central pathology. Magnetic resonance imaging is the preferred imaging modality when conditions such as multiple sclerosis, vascular infarction or cerebropontine tumor are suspected. Computerised tomography is superior to detect any petrous bone abnormality or cerebellar hemorrhage and as a follow up tool for trauma induced vertigo.
- An acute and severe episode of vertigo, regardless of the underlying cause, will usually settle by itself within 24–48 hours due to the effect of brainstem compensation. During the acute phase, supportive measures, bed rest, anti-emetics and vestibular blocking agents can be used to provide symptomatic relief.
- Betahistine also selectively increase the blood flow to the inner ear.
- A combination of an antihistamine (example, promethazine) and an antiemetic is commonly used.
- The use of vestibular blocking agents can delay the compensatory mechanism of brainstem and prolong the symptoms of vertigo. In addition, these medications carry risks of side effects. Therefore, prolonged use of symptomatic medications for acute vertigo is best avoided, especially if a specific treatable cause is identified.
- Benign paroxysmal positional vertigo (BPPV) is the most common underlying cause of vertigo. The pathophysiology of BPPV is the lodgement of a ‘canalith’ inside the posterior semicircular canal. A canalith is made up of small crystals of calcium carbonate that have detached from the utricle in the vestibule of the inner ear. Movement of the canalith activates vestibular hair cells to create an overall asymmetrical vestibular input.
- Patients usually experience a brief but intense vertigo when they turn in bed at night or change their head position.
- The most important clinical test to perform is the DixHallpike manoeuvre. A positive Dix-Hallpike manoeuvre serves three purposes: to confirm the diagnosis, to localise the affected side, and to demonstrate canalith mobility.
- The Epley or canalith repositioning manoeuvre (Brandt-Daroff exercises or the Semont manoeuvre) is a safe and effective way to treat BPPV.
- Vestibular neuritis and labyrinthitis are sometimes used interchangeably but are two separate conditions. Vestibular neuritis describes an inflammation of the vestibular nerve which results in severe vertigo that usually lasts for days, whereas in labyrinthitis hearing loss is an additional feature.
- Viruses such as mumps and influenza are thought to be the causative organisms.
- Cerebellar infarction is the major differential diagnosis and should always be considered.
- During the acute phase, patients benefit from bed rest and short-term symptom relief treatments.
- A high dose of prednisolone (125 mg) is given and the dosage is slowly tapered down over 18 days. Antiviral medication has not been shown to be of any benefit.
- In patients with suppurative labyrinthitis, usually following a bacterial otitis media infection, hospitalisation with intravenous antibiotic treatment is required.
- Early mobilisation as tolerated in a safe environment will encourage the brainstem compensatory mechanism. Vestibular rehabilitation exercises can also be introduced to allow a more rapid and complete compensation of vestibular function.
- Meniere disease is caused by an idiopathic abnormal dilatation of endolymphatic organ producing symptoms of progressive vertigo, tinnitus, aural fullness and fluctuating low frequency hearing loss.
- There is no cure for Meniere disease so treatment is focused on relieving the debilitating vertigo.
- Acute treatment of an attack is bed rest, and antiemetic and vestibular blocking agents.
- A low salt diet (<1-2 gm/day), diuretics and betahistine all are recommended treatments.
- In patients with severe debilitating vertigo, labyrinth ablation therapies with intratympanic gentamicin injection or surgical repair or removal of the labyrinth are required if conservative and medical treatments have failed.
- Unfortunately, there is currently no effective treatment for hearing loss and tinnitus. Regular clinical assessments and formal hearing tests are important to monitor disease progression.
- Migrainous vertigo is a relatively common but underdiagnosed condition.
- Typical migrainous headache can be absent, and both spontaneous and positional vertigo can be associated with migraine.
- It is important to make an accurate diagnosis as patients usually respond well to lifestyle changes, migraine treatments and prophylaxis. There is no definitive diagnostic test for migraine and sometimes the diagnosis can only be verified by the response to the migraine treatment.
- The most feared diagnosis of true vertigo is a transient ischaemic attack or stroke. These are not uncommon conditions, especially among patients with cardiovascular risk factors and central neurological findings, and should always be excluded.
- The emphasis on management is in detailed assessment, urgent hospital referral, and neuroimaging in suspected cases.
- Long term cardiovascular risk factors modification and anticoagulation treatment can help prevent further episodes.
- Acoustic neuroma and multiple sclerosis rarely produce an isolated vertigo without any other symptoms and signs.
- The presence of hearing impairment or cerebellar signs in patients with vertigo should always raise suspicion.
- Anxiety disorder, hyperventilation and depression can all manifest as chronic vertigo.
- Reassurance from the clinician addressing any underlying fears is the only treatment required.
- In more persistent cases, referral for counselling services, cognitive behavioral therapy and selective serotonin reuptake inhibitors might be useful.
- About 80% of patients experience vertigo following head trauma and 20% of these patients continue to have residual vertigo at 6 months.
- Head trauma can either cause direct injury to the labyrinth and its central connections or can cause a canalith dislodgement resulting in a BPPV-like syndrome, which can be treated accordingly.
- Cervical vertigo, which occurs following a whiplash neck injury, is a specific syndrome of dizziness associated with neck pain. Treatment is done with physiotherapy and neck immobilisation.
- A perilymphatic fistula, commonly due to barotrauma, is typically found in people who work in an environment with sudden atmospheric pressure changes, such as pilots or divers. The fistula will usually heal after 2 weeks from the onset of symptoms with appropriate bed rest and avoidance of straining and coughing. Initial and follow up audiological assessments are mandatory and surgical repair is required if there is progressive hearing loss.
- While the brainstem has an amazing ability to restore the homeostasis from a vestibular or central insult, the extent of the compensation can be limited, especially in the elderly population.
- Exercise and movement based vestibular rehabilitation programs are designed to implement visual cues and other techniques to achieve a better functional recovery.
- It is safe and effective treatment for unilateral peripheral vestibular disorders, including post labyrinthectomy vestibular dysfunction.
- Rebuilding the confidence in mobilisation and implementation of fall preventive measures can allow resumption of independent living for elderly patients with impaired vestibular function.
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