Office Vestibular “Bedside” Examination
OVERVIEW
Proper identification of causes for symptoms of dizziness, vertigo, and imbalance includes both thorough case history and office vestibular “bedside” examination. The bedside examination may include evaluation of oculomotor function, vestibular reflexes (vestibulo-ocular, vestibulo-spinal), and signs of static (i.e., with the head still) and dynamic (i.e., with head movements) vestibular system imbalance (Eggers & Zee, 2003). The examination is excellent for acute patient care, in-patient assessment, and patients who cannot complete formal laboratory testing (e.g., pediatric patients). The measures aid in differentiating between peripheral (unilateral and bilateral) and central impairments (Table 3–1). Additionally, the bedside measures helps the clinician to determine areas of focus for quantifying abnormalities on formal laboratory assessment.
Table 3–1. Common Signs Observed in Peripheral Vestibular and Central Disorders
Note: VOR = vestibulo-ocular reflex
Source: Leigh & Zee, 2015.
BEDSIDE PROCEDURES AND INTERPRETATIONS
The evaluation begins with a general inspection of the patient’s head and body posture, gait, and eye coordination:
• Head/body posture: Examine the patient’s body posture while standing and sitting. Look for indications of head tilt, which may be related to peripheral vestibular system disturbance (tilt toward side involved) or possible central signs such as superior oblique palsy (tilt away from the side involved; Leigh & Zee, 2015).
• Gait and transfers: Make notes on abnormalities with observed gait (e.g., slow gait, wide base of support, signs of ataxia, reduced or lack of arm swing, slowness initiating walking, en bloc movement). Validated gait measures such as the Dynamic Gait Index (Shumway-Cook, Baldwin, Polissar, & Gruber, 1997) or Functional Gait Assessment (Wrisley, Marchetti, Kuharsky, & Whitney, 2004) may aid in quantifying gait performance and determining falling risk.
• Eye coordination: Observe signs of disconjugate gaze, abnormalities of eyelids (e.g., ptosis, eyelid retraction, and lid nystagmus), and pupil differences that are enhanced in dim light (Leigh & Zee, 2015; Welgampolo, Bradshaw, Lechner, & Halmagyi, 2015).
Ocular and Neck Range of Motion Tests
Before initiating bedside assessment measures, range of motion examinations are recommended. These screening measures are necessary to document restrictions in both ocular and neck movements that may impact the interpretation of bedside measures.
Ocular Range of Motion Test
The extraocular range of motion test isolates each extraocular muscle and evaluates cranial nerves III (oculomotor), IV (trochlear), and VI (abducens). During the test, the patient is instructed to keep their head still and to follow a target (e.g., examiner’s finger) with their eyes only. The target should be positioned at the patient’s eye level ~18 inches from their nose (Shepard & Telian, 1996). The examiner then slowly makes an H-pattern with the target to isolate each extraocular muscle (Figure 3–1). Shepard & Telian (1996) recommend ~30–35° movements for each portion of the H-pattern, allowing pauses to investigate for gaze-evoked nystagmus with fixation present.
• Normal: Conjugate eye movements/no eye restrictions, smooth and fluid eye movements
• Abnormal: Restriction of eye movements, nystagmus (direction fixed or direction-changing), or disconjugate eye movements
Neck Range of Motion
Positional testing to screen for benign paroxysmal positional vertigo (BPPV) may be performed at bedside or during formal laboratory testing. Details of these procedures are provided in Chapter 4. The provocative testing requires cervical rotations (~45°) and hyperextension of the neck to properly position the semicircular canals. Evaluation of neck restrictions is necessary to determine if modifications to standard screening procedures are needed or if there are any contraindications (e.g., vertebrobasilar insufficiency) to testing. In general, reductions in neck range of motion are common secondary to vestibular and cervicogenic impairment as a means to decrease symptoms. A neck range of motion examination is beneficial not only for assessment planning but also for therapeutic considerations (e.g., neck therapy).
Figure 3–1. Schematic of extra-ocular range of motion (H-pattern) isolating each extraocular muscle and corresponding cranial nerve (CN).
Neck range of motion: The examiner should be seated or standing directly in front of the patient to observe neck restrictions. Ask the patient to turn his/her head to the right, left, up (extension) and down (flexion) and document any restrictions and pain with the movements. It is also helpful to record the onset of symptoms (e.g., dizziness or lightheadedness) with cervical movements that may point toward a cervicogenic cause.
Oculomotor Examination
Smooth Pursuit Test
The smooth pursuit test screens for the ability to smoothly follow a target oscillating in the horizontal or vertical planes. Abnormalities in test performance may suggest impairment of the vestibulocerebellum; however, smooth pursuit tracking declines with age (Leigh & Zee, 2015). During the test, both the examiner and the patient are seated. The patient is asked to move their eyes only to follow a target smoothly (e.g., examiner’s finger) held at eye level ~18–24 inches away. The examiner oscillates the finger at a slow pace (<1 Hz) in both horizontal and vertical directions. The movements should be performed for 3–5 oscillations in each direction. It is important to not move the target greater than 15° to the right, left, up, or down from the center position.
• Normal: Smooth, conjugate eye movements
• Abnormal: Saccadic pursuit (catch-up saccades/saccadic interruptions observed) suggesting a problem within the vestibulocerebellum
• Normal: Smooth, conjugate eye movements keeping up with the target
• Abnormal: Eyes are taken off-target (examiner’s nose), saccadic eye movements
Saccade Test
The saccade test screens for brainstem/cerebellum involvement, and examines the ability to produce rapid, conjugate movements of the eyes to place an object of interest on the fovea (Leigh & Zee, 2015). During the test, both the examiner and patient are seated. The patient is instructed to focus on a target (e.g., examiner’s nose) while the examiner holds up a finger positioned to the right or left. The patient is instructed to look back and forth between the examiner’s finger and nose on command, typically requiring a 15–20° eye movement to view the targets. This task should be repeated several times for horizontal, vertical, and oblique (diagonal) movements, and should be performed for 2–3 repetitions in each direction. The examiner looks for the number of eye movements and speed at which it takes the patient’s eyes to reach the target.
• Normal: Quick, accurate movements of eyes between targets
• Abnormal: Slow eye movements or inability to accurately move eyes to target
○ Slow speed may suggest brainstem involvement
○ Abnormal accuracy to refocus the eyes on the target that may suggest cerebellar involvement
Static Vestibular Examination
Spontaneous Nystagmus and Gaze-Evoked Nystagmus Testing
Spontaneous nystagmus is a clinical sign of “static” imbalance in the vestibular system that may arise from peripheral and/or central causes (Eggers & Zee, 2003). Testing is first performed with fixation (i.e., the patient looking in center gaze position at a target) and then with fixation removed (i.e., use of Frenzel lenses or video-oculography system). Gaze is held for at least 15–20 seconds.
Next, the clinician asks the patient to look with eyes only in eccentric gaze positions (right, left, up, and down), both with and without visual fixation. As indicated in Chapter 1, nystagmus characteristics (e.g., jerk vs. pendular) and presence of saccadic intrusions (e.g., square wave jerks) should be described to aid in differentiating peripheral from central causes of static imbalance (Eggers et al., 2019).
• Abnormal: Evidence of nystagmus and saccadic intrusions
○ Unilateral peripheral vestibular loss may demonstrate direction fixed horizontal/horizontal torsional jerk nystagmus beating toward the more active neural side (typically away from the lesioned side). Nystagmus pattern follows Alexander’s law (enhanced when looking in the direction of the beat of the nystagmus) and enhanced with fixation removed (Leigh & Zee, 2015).
○ Central disorders may demonstrate signs of nonlinear or direction changing jerk nystagmus enhanced with fixation present. The nystagmus pattern may be pure vertical or torsional. Additional evidence of saccadic intrusions or other nystagmus patterns (pendular) suggests a possible central cause (Leigh & Zee, 2015).
Cover-Cross-Cover Test
Signs of skew deviations may be uncovered during the bedside examination. Skew deviation or ocular (vertical) misalignment may indicate an imbalance of the otolith-ocular reflex (Eggers & Zee, 2003), which is part of the ocular tilt reaction (OTR) that occurs after unilateral otolith dysfunction. The OTR is the combination of head tilt, skew deviation, and ocular counter-rolling, all in the same direction. The direction of the OTR suggests the side of the vestibular (utricle or vestibular nucleus) impairment. Case history and other clinical signs help to differentiate OTR from other central involvement.
The cover-cross-cover test evaluates for skew deviation. During this test, the patient is asked to stare at a near target (e.g., examiner’s nose at a distance of about 14 inches from the patient’s eyes). With both hands, the examiner covers the patient’s eyes and then alternately removes one hand to look for vertical adjustments of the “uncovered” eye.
• Normal: No observed deviations of the eyes
• Abnormal: Observed corrective saccade of the uncovered eye, either bringing the uncovered eye positioned too low upwards or bringing the uncovered eye positioned too high downwards to refocus on the target; the side of the lower eye position suggests the side of the OTR
Subjective Visual Vertical Test
Bedside subjective visual vertical (SVV) testing such as the SVV bucket method (Zwergal et al., 2009) is an additional measure of otolith-ocular imbalance. The patient is asked to indicate when a line inside of a bucket is positioned vertically: the examiner measures the perceived point of vertical against a true vertical reference point on the back of the bucket.
• Normal: SVV perceived within 2°–3° of true vertical.
• Abnormal: SVV >3° of true vertical suggests acute otolith or vestibular nuclei impairment toward the side of the vertical offset; however, central abnormalities (upper brainstem) may also result in deviations, suggesting contralateral impairment (Zwergal et al., 2009).
Dynamic Vestibular Examination
Head Impulse Test (HIT)
The HIT examines high-frequency VOR function: the ability to maintain visual fixation on a target (e.g., clinician’s nose) with rapid head movements. The test evaluates the function of each semicircular canal (SCC), concerning functional pairs: right and left horizontal SCCs, right anterior and left posterior SCCs (RALP), and left anterior and right posterior SCCs (LARP).
Horizontal HIT: The examiner should be seated directly in front of the patient for testing. The examiner tilts the patient’s head down 30° and then asks the patient to stare at either the examiner’s nose or near the target (~1 meter away) positioned on the wall. The examiner then places his/her hands on the patient’s head and quickly turns the head to the right and left in small, unpredictable range of motion movements. The examiner observes the patient’s eyes during and immediately following the head movements.
• Normal: Eyes remain fixed on the target with no evidence of a corrective saccade observed after the head movement.
• Abnormal: The presence of a corrective saccade when stimulating (turning head) to the right, left or both sides indicating reduced VOR gain (i.e., eye movements that are not compensatory to head movements).
Vertical HIT: Again, the examiner should be seated directly in front of the patient during the test. The patient is instructed to maintain eye gaze toward the center target used during horizontal canal head impulses. There are two methods to perform vertical canal head impulses:
Method 1: The examiner places their hands on the patient’s head, and moves the head in the plane of each canal. For example, to test RALP, the examiner moves the patient’s head in a small arc down and to the right (stimulating the right anterior SCC) and then back and to the left (stimulating the left posterior SCC).
Method 2 (preferred): The examiner turns the patient’s head ~40–45° toward the posterior canal to be stimulated and makes vertical movements of the head. For example, to test RALP, the patient’s head is turned to the left (toward the left posterior SCC).
• Normal: Eyes remain fixed on the target with no evidence of a corrective saccade observed after the head movement
• Abnormal: The presence of a corrective saccade after stimulating one or multiple vertical canals indicating reduced VOR gain
○ Anterior canal dysfunction: corrective saccade noted with the rapid rotation of the head downwards
○ Posterior canal dysfunction: corrective saccade noted with the rapid rotation of the head upwards
Low-frequency VOR function may be examined at the bedside during the slow VOR test. During this test, the patient is instructed to focus on a stable target (e.g., examiner’s nose positioned directly in front of the patient), while the examiner slowly moves the patient’s head horizontally or vertically. The examiner looks for the presence of catch-up saccades in one or both directions suggesting impaired VOR function (Eggers & Zee, 2003).
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