The Virtual (Telemedicine) Ocular Motor Examination

𝗢𝗿𝗶𝗴𝗶𝗻𝗮𝗹 𝗗𝗲𝘀𝗰𝗿𝗶𝗽𝘁𝗶𝗼𝗻: This document is based on Approach to the Ocular Motor & Vestibular History and Examination: https://collections.lib.utah.edu/ark:/87278/s64x9bq1, but adapted and edited for the telemedicine exam. Virtual Ocular Motor Examination • Convergence: instruct the patient to focus on their thumb held at arm's length, and slowly move their thumb towards their nose. This may bring out or cause reversal of vertical nystagmus (e.g., transition from upbeat to downbeat nystagmus in Wernicke's encephalopathy [see example of transition from DBN to UBN with convergence in brainstem encephalitis - https://collections.lib.utah.edu/ark:/87278/s6bg75c3]; see example of increased ocular flutter and UBN with convergence with a posterior fossa tumor - https://collections.lib.utah.edu/ark:/87278/s6867r9v), may exaggerate other acquired forms of nystagmus, and damp congenital/infantile nystagmus. If the patient complains of binocular symptoms or double vision while reading and near viewing and the patient has a near point of convergence >10 cm, think about convergence insufficiency (particularly with parkinsonism [https://collections.lib.utah.edu/details?id=1253803] or TBI/concussion). • Saccades: instruct the patient to make rapid movements of their eyes in each gaze direction, noting the speed, conjugacy, latency, and accuracy. First have the patient look between an eccentric target and the camera horizontally and vertically, making assessment of accuracy easier - e.g., overshooting the camera (hypermetria) or undershooting the camera (hypometria). Then have the patient make larger amplitude saccades horizontally and vertically, which makes assessment of speed and conjugacy easier (e.g., adduction lag suggests an internuclear ophthalmoplegia [INO], https://collections.lib.utah.edu/details?id=187742). Saccadic dysmetria is seen in cerebellar disease (or brainstem connections w/ cerebellum [https://collections.lib.utah.edu/details?id=187722&q=saccadic+dysmetria&fd=title_t%2Cdescription_t%2Csubject_t&facet_setname_s=ehsl_novel_gold]). Ipsilateral hypermetria and contralateral hypometria occurs in Wallenberg syndrome (https://collections.lib.utah.edu/details?id=187724). Slow saccades of restricted amplitude occur in motor nerve paresis or muscle weakness. • Smooth pursuit: instruct the patient to hold their head steady, fix their eyes on the camera and slowly move the camera in the horizontal and vertical planes. Or, have the patient focus on their outstretched thumbnail (or other small fixation target), while following the slowly moving object horizontally and vertically with the head still. Note saccadic (where saccades substitute for subnormal smooth pursuit gain to catch-up to the target) "choppy" pursuit [https://collections.lib.utah.edu/details?id=1307533]. Impaired pursuit horizontally and vertically is typically seen in cerebellar disease [https://collections.lib.utah.edu/details?id=187722&q=saccadic+dysmetria&fd=title_t%2Cdescription_t%2Csubject_t&facet_setname_s=ehsl_novel_gold] (or its connections). If impairment of pursuit is asymmetric, think about an ipsilesional process - e.g., saccadic or choppy pursuit to the right due to a right hemispheric lesion [https://collections.lib.utah.edu/details?id=187721]. Mild impairments of smooth pursuit may not be evident over a video connection (i.e., due to limited frames per second). • VOR suppression (VORS): instruct the patient to fix on the camera which they should hold in front of their eyes, while turning their torso slowly in the horizontal plane. The vertical plane can then be assessed by instructing the patient to flex and extend the neck under the same conditions. A demonstration by the examiner is essential to guide the patient for this test. VORS will generally be saccadic when pursuit is saccadic and vice versa [https://collections.lib.utah.edu/details?id=1248765]. However, when pursuit is impaired and the VOR is lost (bilateral vestibular loss), VORS can look better than pursuit since there is no VOR to suppress [https://collections.lib.utah.edu/details?id=1256239]. Mild impairments of VORS may not be evident over a video connection (i.e., due to limited frames per second). • Fixation and gaze-holding: assess for nystagmus or saccadic intrusions by observing the eyes in primary position. Then instruct the patient to look in each position of gaze, and to hold that position to assess for gaze-evoked nystagmus. In doing so, motility can also be evaluated with both eyes viewing (versions). • Range of motion (ductions): check the range of each individual eye (ductions) if there is diplopia or if a motility deficit is suspected. Instructing the patient to hold their head 20o to the right or to the left may provide a better view of the range of horizontal gaze, if there is diplopia or if a motility deficit is suspected (see example of a partial 6th nerve palsy diagnosed on the virtual exam - https://collections.lib.utah.edu/ark:/87278/s6j15pj5) . • Ocular alignment: the alternate cover test can be performed by instructing the patient to hold their head steady, fix their eyes on the camera (or a more distant target - the closer the fixation target, the more of an exodeviation the examiner will see), and use their cell phone (or a spoon) to occlude one eye and then the other eye, back and forth. This test can be also be completed with the patient's head held at 20o off center in the horizontal and vertical planes, which may help in localization of abnormalities (e.g. differentiating the alternating hypertropias of bilateral 4th nerve palsies from alternating skew deviation [https://collections.lib.utah.edu/details?id=1383125&q=skew+deviation&fd=title_t%2Cdescription_t%2Csubject_t&facet_setname_s=ehsl_novel_gold]). Look for a horizontal (when the eye under cover is crossed in so that it has to move outward when uncovered to take up fixation - ESO [https://collections.lib.utah.edu/details?id=1256238]; when the eye under cover is deviated outward so that it has to move inward when uncovered to take up fixation - EXO [https://collections.lib.utah.edu/details?id=1253803]) or vertical (generally named after the side of the higher eye - e.g., if the right eye is uncovered and has to come down to fixate on the target, this is a right hyperdeviation) movements of the uncovered eye. The eso-, exo-, hyper is further classified as a tropia (misalignment present with both eyes open - use a cover-uncover technique on each eye individually) or phoria (misalignment present when binocular vision is broken with alternate cover testing but no misalignment with cover-uncover). Any change in deviation or lack thereof helps in the localization. • Optokinetic nystagmus (OKN): one way this can be examined virtually is using a smartphone application (e.g. Eye Handbook © app used in this video) or optokinetic tape/flag/drum held in front of the examiner's camera. The optokinetic stimulus should occupy the full screen of the patient's device (easier to elicit and appreciate OKN using a computer screen rather than a smartphone). Instruct the patient to move close to their screen, focus on an area of the screen close to the lens of the camera, and count the stripes as they pass. The slow phases represent smooth pursuit while the fast phases represent saccades. Since the optokinetic stimulus used does not involve full visual field stimulation (e.g., looking out the window at passing scenery from a moving train), this is not a true OKN. Situations in which the virtual or bedside examination [https://collections.lib.utah.edu/details?id=1307320] of OKN can be helpful include: 1) rapid assessment of symmetry and presence/absence of pursuit/saccades in an uncooperative or difficult to examine patient, 2) it can help to bring out a subtle adduction lag in INO [https://collections.lib.utah.edu/details?id=1278693] (3) one of the first ocular motor signs of PSP is loss of the downward fast phase to an optokinetic stimulus directed upward [https://collections.lib.utah.edu/details?id=1290930] (4) if nystagmus is seen in a patient with functional monocular (when the good eye is occluded) or binocular blindness, this suggests that the patient has at least some vision, 5) since upward saccades are often affected in dorsal midbrain (Parinaud's syndrome), vertical OKN can demonstrate this and convergence retraction nystagmus (when stimulus is directed downward). Virtual vestibular examination • Dix-Hallpike Maneuver: used to test for posterior canal (PC) BPPV. The patient can be guided through a self-administered Dix-Hallpike (DH) maneuver using two techniques. The safety of the patient should be prioritized when completing these tests virtually, and the examiner should avoid putting the patient in a position where a fall may occur. When the test is positive [https://collections.lib.utah.edu/details?id=1281863] the nystagmus 1) typically begins with a short latency (sometimes as long as 30 secs) after change in head position, 2) lasts less than 1 min, 3) fatigues with repeated testing, and 4) often reverses direction (downbeat-torsional towards the left ear with right PC-BPPV) when the patient sits up again [https://collections.lib.utah.edu/details?id=1281864] o Floor (or bed) Dix-Hallpike: this test can be used for patients who are fully mobile and able to get down to the floor and up again without assistance. Instruct the patient to sit upright on the floor and place a pillow directly behind them (which will align to their mid-back when lying supine). Then have the patient turn their head 45o to the right/left and lie back quickly, with proper placement of the pillow allowing the head/neck to extend slightly as they lie back. The patient should hold the camera in front of their eyes throughout the maneuver. Assess for nystagmus and symptom provocation. If dizziness is provoked, allow the patient sufficient time to recover before instructing them to sit up. Have the patient keep the camera on the eyes as they sit up to see if there is reversal of the nystagmus (see example in PC-BPPV - [https://collections.lib.utah.edu/ark:/87278/s6ng8nbm] .o Modified (chair) Dix-Hallpike:(1) this test can be used for patients who may not be able to safely undertake the traditional Dix-Hallpike. Instruct the patient to sit at the front of the chair, turn their head 45o to the right/left and sit back quickly, allowing their neck to extend slightly over the back of the chair. The patient should hold the camera in front of their eyes throughout the maneuver. Assess for nystagmus and symptom provocation. If dizziness is provoked, allow the patient sufficient time to recover before instructing them to sit up. When nystagmus is provoked, continue to observe the eyes after returning to an upright seated position to evaluate for reversal. • Supine roll test: used to test for horizontal canal (HC) BPPV. While horizontal nystagmus due to HC-BPPV is often seen with DH, the roll test will usually maximize nystagmus and vertigo with the HC variant. The patient can be guided through a self-administered supine roll test while lying on the floor or bed. Instruct the patient to lie supine with a pillow under their head (so the head is flexed 20-30o, making the HC perpendicular to the ground), then turn their head (or their whole body and head) 90o to the right/left. Assess for nystagmus and symptom provocation, and instruct the patient to return to the initial supine position before testing the opposite side. Nystagmus seen in HC BPPV may be geotropic [https://collections.lib.utah.edu/details?id=1281862] or apogeotropic [https://collections.lib.utah.edu/details?id=1281861], and the nystagmus is more intense when beating toward the affected ear. If dizziness is provoked, allow the patient sufficient time to recover before instructing them to sit up. • Active head impulse test (HIT): instruct the patient to fix their eyes on the camera and turn their head 20o to the right/left, and then make a rapid movement toward the midline to align their head with the camera again, keeping their eyes fixed on the camera throughout. A simple instruction is to ask the patient to move the head from the initial eccentric position back to a neutral position as quickly as they can. The test can also be completed with rapid movements away from the midline (thus making the maneuver less predictable for the patient - however, it is not clear that one method is superior to the other for the purposes of the active HIT). In the case of an acute right peripheral vestibulopathy (e.g., vestibular neuritis), a rightward HIT will result in the eyes moving to the right with the head initially, so that a corrective re-fixation saccade will be needed to move the eyes back to the target, or to the left. This is considered an abnormal or positive HIT and generally suggests a peripheral process (although there are exceptions). Note that a mildly abnormal HIT may not be detectable virtually, as patients may struggle to achieve the same rapid velocity of head movement and rapid deceleration that are controlled by the examiner during the passive bedside HIT [https://collections.lib.utah.edu/details?id=187678] . Also, the unpredictability of the passive (bedside) HIT makes it more challenging for patients to make compensatory (covert) saccades during the head movement. Even a patient with known severe vestibular loss may or may not have an abnormal active HIT (see example [https://collections.lib.utah.edu/ark:/87278/s6d84xrj]. • Dynamic Visual Acuity: the examiner can use screen-sharing to provide a visual acuity chart. Instruct the patient to sit at the appropriate distance from their screen at which the lowest line on the visual acuity chart is just readable. Have the patient move their head (horizontally to evaluate the horizontal SCC and vertically to evaluate the anterior and posterior SCC function) at ~2 Hz while viewing the chart. A decrease in best-corrected acuity of 2 lines or more from baseline is considered abnormal - patients with unilateral vestibular loss may loss 2-3 lines prior to compensation, while patients with bilateral vestibular loss will often lose 4 or more lines. Encourage the patient to keep moving their head throughout, as patients may have a natural tendency to slow or interrupt their active head movements in order to best visualize the target. • Penlight cover test (partial removal of fixation): during in-person clinical encounters, the maneuvers below are best tested with complete (or near complete) removal of fixation (e.g., Frenzel or video Frenzel goggles). Removal of fixation is more challenging during virtual evaluations but can be approximated using the penlight cover test. Instruct the patient to go into a dark area and shine a light from a cell phone or torch into one eye (holding the light source at a distance of 2-3 inches from the eye to make fixation more challenging due to the brightness of the light) while occluding the fellow eye with the other hand. Assess for spontaneous nystagmus or nystagmus in eccentric gaze. If a dark area is not available, the following tests can be completed in normal lighting, but abnormalities may be more subtle since removal of fixation will accentuate peripheral vestibular nystagmus. o Head-shaking: instruct the patient to close their eyes and perform active rapid head-shaking at 2-3 Hz for ~15 secs. If a unilateral vestibulopathy is present, head-shaking-induced (contralesional) nystagmus is often provoked, with the slow phase toward the affected ear. With central lesions, the nystagmus may be vertical (see example - [https://collections.lib.utah.edu/details?id=1550674] or may change direction from the baseline spontaneous nystagmus. If there's strong HSN without clear unilateral vestibular loss [https://collections.lib.utah.edu/details?id=1295175] , think about a central process. o Hyperventilation: instruct the patient to breathe rapidly in and out of their mouth for 40-60 seconds. Alkalosis and changes in ionized calcium may improve conduction through an affected segment of 8th cranial nerve due to vestibular schwannoma [https://collections.lib.utah.edu/details?id=1213447] or neurovascular compression, usually causing an excitatory (ipsilesional) nystagmus. When a chronic vestibular imbalance has been compensated for by central mechanisms, hyperventilation can cause a transient decompensation and bring out nystagmus with an ipsilesional slow phase. Hyperventilation can enhance/produce downbeat nystagmus in cerebellar disease [https://collections.lib.utah.edu/details?id=1427580]. o Valsalva (closed glottis or pinched nose): instruct the patient to take a deep breath and ‘bear down' (closed glottis) or take a deep breath and ‘try to pop their ears' (pinched nose). Assess for nystagmus. In superior canal dehiscence, pressure changes may be transmitted to the superior canal, causing an excitatory pattern of nystagmus with the nose pinched [https://collections.lib.utah.edu/details?id=1307322] , or an inhibitory pattern with Valsalva against a closed glottis. o Vibration: instruct the patient to self-administer this test with an electric toothbrush or vibrator/massager, if available. Vibration of the mastoids and vertex will induce an ipsilesional slow phase with unilateral vestibular loss [https://collections.lib.utah.edu/details?id=1427582]. 𝗡𝗲𝘂𝗿𝗼-𝗼𝗽𝗵𝘁𝗵𝗮𝗹𝗺𝗼𝗹𝗼𝗴𝘆 𝗮𝗻𝗱 𝗡𝗲𝘂𝗿𝗼-𝗼𝘁𝗼𝗹𝗼𝗴𝘆 𝗧𝗲𝘅𝘁𝗯𝗼𝗼𝗸 𝗟𝗲𝗴𝗲𝗻𝗱: This video demonstrates one approach to performing the ocular motor examination virtually in a normal subject. (Video created with the assistance of Dr. Olwen Murphy) https://collections. lib.utah.edu/ark:/87278/s6x9815p