Written by Travis M. Moore
Last edited 23-Sep-2019
Bedside tests allow the clinician to make gross assessment of a patient's balance without the use of any equipment (though some bedside tests can be augmented with hardware and software). The bedside examination is an excellent way to test potential diagnoses gathered from the case history and further narrow the likely cause of the patient's symptoms. Diagnostic test are still necessary, because bedside assessments do not allow the clinician to record or quantify the results. Furthermore, bedside tests are only sensitive to large vestibular impairments.
It is important to establish the patient has a full range of eye movements before starting vestibular testing. For example, if there is an extraocular muscle (EOM) paresis (weakness), results from that eye will be contaminated.
Assessment the range of EOM movement can be done by asking the patient to follow your index finger. Hold your index finger roughly 12 inches in front of the patient and slowly move it to the right and left in a smooth motion. Ensure the patient's eyes are able to track your finger to both sides. Repeat in the vertical direction.
This is also an opportune time to look for spontaneous nystagmus (SN). As the patient to focus on your index finger again, this time holding it approximately 4 feet in front of the patient. Look for any movement of the pupil consistent with nystagmus.
The head impulse test (HIT) tests the oculocephalic reflex, or "doll's eye reflex." This terminology comes from dolls whose eye open and close as they are laid flat then made to "sit up." Similarly, we will examine whether there is any eye movement when quickly turning a patient's head during fixation.
Grasp the patient's head in your hands and tilt it downward 30 degrees. This will put the horizontal canals roughly parallel to the ground for maximal effectiveness. Instruct the patient to fixate on your nose throughout the test, and to relax their neck to avoid injury during rotation. When ready, use your hands to turn the patient's head to one side (~ 20 degrees) in a short, quick motion. Watch the patient's eyes during this movement to ensure they stay fixated on your nose during the turn. You should also look for a "catch-up saccade" immediately after the movement. That is, if the patient has a weak VOR, the eyes will move with the head, and a saccade will be required to bring the eyes back to your nose after the head turn.
REFERENCESBaloh, R. W., & Honrubia, V. (2001). Clinical Neurophysiology of the Vestibular System (Third ed. Vol. 18): Oxford University Press, Inc.