Vestibular hypofunction is defined by Medicine Net as a condition in which a person experiences dizziness or disorientation caused by problems within the entrance--or vestibule--of the ear. It is in this vestibule that biological systems are contained that control the person's equilibrium and sense of balance.
Vestibular hypofunction can produce different effects depending on the severity and whether or not it exists in one or both ears. If the condition exists only in one ear, it is referred to as unilateral vestibular hypofunction. A fluctuation in neuron firing patterns in one ear convinces the brain that the head is rotating, which causes balance issues and instability. If the condition extends to both ears, it is known as bilateral vestibular hypofunction and can cause more debilitating symptoms such as vertigo. The onset of this condition can be either unilateral, or bilateral.
The Journal of American Physical Therapy Associates suggests that unilateral vestibular hypofunction is usually a result of vestibular neuronitis, often caused by the herpes simplex virus. Meniere disease, brain injury and vestibular schwannoma can also cause the unilateral iteration of the condition. Bilateral vestibular hypofunction is commonly caused by aminoglycoside antibiotics, which are known to damage vestibular hair cells. It may also be caused by tumors, head trauma, BVH meningitis and extensive problems with unilateral vestibular hypofunction.
The most common symptom of vestibular hypofunction is spatial disorientation, which usually worsens with head movement. Sufferers can have difficulty moving around, sight problems, vertigo experiences, difficulty maintaining good posture, and a restricted sense of balance. Performing tasks that create high-frequency oscillations such as driving on an uneven road can also prove to be challenging.
There are a variety of procedures that a doctor can undertake in order to diagnose vestibular hypofunction. A doctor may perform an eye examination while the patient is moving, and can also monitor how the patient's brain reacts to certain motor movements such as quick head rotations or thrusts. Cold or warm water may be poured into the ear canal to measure the influence a change of temperature has on the condition. If vestibular hypofunction is suspected, one further test is to spin the patient in a swiveling chair and monitor brain activity compared with what would be considered normal activity.
If the vestibular hypofunction is a result of another underlying problem, that problem should be resolved first. Rehabilitation can continue with basic therapies and adaptation exercises such as those to improve balance and muscle strength.