What is Vertigo?
Vertigo is best described as a sensation of dizziness or spinning, and is considered a symptom rather than a disorder per se. It can also lead to a variety of other symptoms such as nausea, imbalance, headache, fullness in the ear, and tinnitus — which is a ringing sensation inside the ear. Another symptom is nystagmus which consists of abnormal, involuntary, rapid eye movements. However, these symptoms can sometimes resemble light-headedness, which usually has causes unrelated to the balance system. A number of diagnostic tests can be used to determine the cause and nature of vertigo—whether central or peripheral.
Conditions That Cause Vertigo
Common conditions that lead to vertigo include:
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Benign Paroxysmal Positional Vertigo (BPPV): This is a type of vertigo induced by sudden changes in head position that can cause brief episodes of mild to intense dizziness. Certain repositioning procedures are often advised to manage this condition, with each position held until any symptoms or nystagmus resolves. These are generally effective after one or two sessions.
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Vestibular neuritis and Labyrinthitis: This condition results in the inflammation of the vestibular nerve and the inner ear labyrinth respectively. While vestibular neuritis causes only symptoms of vertigo, labyrinthitis causes cochlear symptoms such as hearing loss, and tinnitus.
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Cholesteatoma: This condition is characterised by a benign growth that develops in the middle ear, behind the tympanic membrane. It can be caused either due to repeated middle ear infections, or due to poor eustachian tube function. As the growth increases in size, it can cause damage to the surrounding structures that can result in hearing loss, vertigo, and facial muscle problems.
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Meniere’s Disease: This condition is characterized by 3 classical symptoms which include vertigo, tinnitus, and hearing loss. It occurs as a result of abnormal endolymph build up in the inner ear and is usually unilateral in nature. Most individuals are typically asymptomatic between episodes.
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Perilymphatic fistula: This is a condition that results from a tear or rupture in the round or oval windows causing perilymph from the fluid filled inner ear to leak into the air filled middle ear. This fluid leakage causes pressure changes in your ear leading to balance and hearing problems.
Other conditions associated with vertigo include migraine, brainstem stroke, cerebellopontine angle tumors, and some demyelinating diseases such as multiple sclerosis.
Assessment:
Assessing vertigo generally involves tests to analyse whether the cause is central or peripheral in nature. To look for important central symptoms of stroke, tumor, demyelination, and other pathologies of the nervous system, the following two tests are generally performed:
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Vestibular Evoked Myogenic Potential (VEMP): This is a neurophysiological assessment technique which is used to assess the function of the otolith organs and the CN VIII. The test involves using surface electrodes to record short latency electromyograms (EMG) of muscle activity, produced by stimulating the ear with high intensity acoustic stimuli. The two main types of VEMP include cervical VEMP (cVEMP) that measures the integrity of the saccule and inferior vestibular nerve, and the ocular VEMP (oVEMP) that measures the utricle and superior vestibular nerve.
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Videonystagmography (VNG): This is a standard balance assessment technique that uses infrared goggles to measure the intensity and direction of involuntary eye movements known as nystagmus. This is done by tracking eye movements during positional changes and a variety of visual stimuli. VNG helps in assisting the diagnosis of vestibular and balance related disorders such as Meniere’s Disease and Superior Semicircular Canal Dehiscence (SSCD).
