Vestibular Assessment: Needed for Balance of the body

In our daily lives, the process of maintaining balance while we move is carried out by the vestibular system. It comprises of the vestibular apparatus present in each year which senses the position of the head in space. From this apparatus, nerves carry the information to the brain where it is processed. Input from the eyes is also integrated to understand visual orientation in space. Any imbalance is immediately sensed and messages are sent to the muscles of the neck and body to maintain stability of the body. Certain diseases can affect this vestibular system leading to classical symptoms.

Symptoms due to diseases affecting the vestibular system

• Vertigo: This is a sensation of instability from the feeling that the room is spinning around you or that you are swaying or tilting in the room. It is very unpleasant and is usually made worse by moving the head.
• Nausea and Vomiting: The sensation of vertigo can trigger nausea with subsequent vomiting.
• Instability of gait: Due to abnormal processing in the vestibular system, the body is unable to maintain balance well.

Diseases affecting the vestibular system

• Benign Paroxysmal Positional vertigo (BPPV): This is one of the most common diseases affecting the vestibular system. This occurs due to the collection of debris made of calcium in the ear canals. The movement of this material within the inner ear can lead to false perception of imbalance and lead to vertigo.
• Vestibular neuritis: This occurs from inflammation of the vestibular nerve
• Meniere Disease: This is a disease of excess fluid in the inner ear canals. This is associated with hearing loss and vertigo along with a feeling of fullness in the ears.
• Herpes Zoster Oticus: The virus causing chicken pox can remain dormant in any of the peripheral nerves of the body and get reactivated in times of decreased immunity and old age. A reactivation of this virus in the facial nerve can cause a hearing loss and vertigo along with rash in the ear canal and facial weakness.
• Otitis Media: This is an infection of the middle ear. The infection can lead to a vertigo and reduced hearing
• Acoustic Neuroma: This is a tumor that grows from the nerve cells of the vestibular nerve. This can cause vertigo and abnormal hearing.
• Aminoglycoside toxicity: Aminoglycosides are a group of antibiotics which are toxic to the inner ear sensory apparatus. This can affect the hearing and vestibular apparatus.
• Multiple Sclerosis: This is a disease with inflammatory plaque formation and degeneration of the central nervous system. The location of the lesions in the regions responsible for balance can cause vertigo.
• Stroke: Any insult to the regions of the brain processing balance, from decreased blood supply or a local bleed can cause vertigo and imbalance.
• Vestibular migraine: This is a subtype of migraines where the severe headache is associated with vertigo.

Assessment of the Vestibular system

A thorough history of your symptoms is recorded. The time course of the vertigo and associated symptoms are important clues to distinguish various causes of vestibular disease. Several different physical exam maneuvers are also performed and offer insight into the diagnosis.

• Gait and Balance testing: the person is made to walk and turn and also stand still with eyes open and closed. Any imbalance is noted. The side towards which there is tendency to fall can suggest the side affected by a lesion.
• Checking for Nystagmus: Nystagmus is a sign where the eyes slowly drift to one side followed by a rapid re-adjustment. This is seen in diseases affecting the vestibular system as well as certain parts of the brain that controls balance. Different patterns of nystagmus is looked for to suggest the site of the lesion. Caloric Testing by infusing warm or cold water or air into the ear produces nystagmus. The pattern and any abnormalities is observed.
• Dix-Hallpike Maneuver: This is a provocative test which involves holding and turning the head to one side followed by quickly lowering the head with the patient in a lying down posture and the head hanging off theside of the examination table. This maneuver can trigger vertigo and nystagmus in patients with BPPV
• Head Impulse Test: This is also called the head thrust test. In this test, the patient is asked to look at a target placed in the distance. The head should be facing about 10° away from straight ahead. Suddenly, the head is moved by about 15° and the movement of the eyes are observed. In normal individuals, the eyes maintain focus on the distant target. However, people with a lesion in the vestibular apparatus may show deviation of the eyes briefly before moving back on the target.
• Rotational Chair Test: This involves the patient being seated in a chair which is then rotated in different sides. Upon rotation, nystagmus is looked for.
• Evaluation of Hearing: Clinically examining hearing using tuning forks is one to identify is the person has a conductive or sensorineural hearing loss. This distinction can narrow the differentials.

Diagnostic Tests for Vestibular system

• Electronystagmography (ENG) and Video nystagmography (VNG): Both these tests are used to accurately record eye movements. ENG uses electrodes and VNG does this using video cameras. The various clinical maneuvers described above can be done along with ENG and VNG to improve diagnostic accuracy.
• Vestibular evoked Myogenic Potentials (VEMPs): This test records muscular movements in response to loud sounds and head vibrations.
• Audiometry: This is to evaluate for hearing loss. The severity of hearing loss can be identified at both high and low frequency and is more accurate that the tuning fork tests.

References:

1. Joseph MF, et al. Evaluation of the patient with vertigo https://uptodate.com/contents/search. Accessed Aug. 18, 2018
2. Vestibular Testing | American Hearing Research Foundation [Internet]. [cited 2018 Aug 22].