Faculty Bibliography

OBJECTIVE: We investigated the King-Devick (K-D) test of rapid number naming as a visual performance measure in a cohort of patients with multiple sclerosis (MS). METHODS: In this cross-sectional study, 81 patients with MS and 20 disease-free controls from an ongoing study of visual outcomes underwent K-D testing. A test of rapid number naming, K-D requires saccadic eye movements as well as intact vision, attention and concentration. To perform the K-D test, participants are asked to read numbers aloud as quickly as possible from three test cards; the sum of the three test card times in seconds constitutes the summary score. High-contrast visual acuity (VA), low-contrast letter acuity (1.25% and 2.5% levels), retinal nerve fiber layer (RNFL) thickness by optical coherence tomography (OCT), MS Functional Composite (MSFC) and vision-specific quality of life (QOL) measures (25-Item NEI Visual Functioning Questionnaire [NEI-VFQ-25] and 10-Item Neuro-Ophthalmic Supplement) were also assessed. RESULTS: K-D time scores in the MS cohort (total time to read the three test cards) were significantly higher (worse) compared to those for disease-free controls (P=0.003, linear regression, accounting for age). Within the MS cohort, higher K-D scores were associated with worse scores for the NEI-VFQ-25 composite (P<0.001), 10-Item Neuro-Ophthalmic Supplement (P<0.001), binocular low-contrast acuity (2.5%, 1.25%, P<0.001, and high-contrast VA (P=0.003). Monocular low-contrast vision scores (P=0.001-0.009) and RNFL thickness (P=0.001) were also reduced in eyes of patients with worse K-D scores (GEE models accounting for age and within-patient, inter-eye correlations). Patients with a history of optic neuritis (ON) had increased (worse) K-D scores. Patients who classified their work disability status as disabled (receiving disability pension) did worse on K-D testing compared to those working full-time (P=0.001, accounting for age). CONCLUSIONS: The K-D test, a <2minute bedside test of rapid number naming, is associated with visual dysfunction, neurologic impairment, and reduced vision-specific QOL in patients with MS. Scores reflect work disability as well as structural changes as measured by OCT imaging. History of ON and abnormal binocular acuities were associated with worse K-D scores, suggesting that abnormalities detected by K-D may go along with afferent dysfunction in MS patients. A brief test that requires saccadic eye movements, K-D should be considered for future MS trials as a rapid visual performance measure.

BACKGROUND: The decision between conservative management and invasive treatment of juxtaorbital intracranial vascular anomalies can be challenging. Whereas arteriovenous malformations (AVMs) can lead to vision loss and are potentially life threatening if they rupture, invasive endovascular and surgical procedures also carry risks. CASE DESCRIPTIONS: Two patients developed blinding orbital congestion soon after successful treatment of cerebral vascular anomalies. The first patient, a 36 year-old man, underwent partial embolization followed by resection of a congenital frontal lobe AVM. The second patient, a 62 year-old woman, underwent embolization of a peri-orbital/skull base dural arteriovenous malformation. Following intervention, both patients developed unilateral vision loss proptosis, chemosis, complete ophthalmoplegia, and elevated intraocular pressure. The first patient suffered from acute orbital compartment syndrome in the absence of any acute localized hemorrhage or thrombosis. The second patient experienced refractory acute glaucoma from orbital congestion, secondary hyphema and angle closure due to superior ophthalmic vein and cavernous sinus thromboses. CONCULSIONS: These cases highlight the potential orbital congestion to worsen acutely after invasive treatment of juxtaorbital cerebral vascular anomalies, and suggest diverse mechanisms of resultant visual and orbital compromise. The first case represents the first report of orbital compartment syndrome following resection of a congenital AVM.

OBJECTIVE: To describe a novel neurophysiologic signature of the retinal ganglion cell and to elucidate its relationship to abnormalities in validated structural and functional measures of the visual system. METHODS: We used multifocal electroretinogram-generated optic nerve head component (ONHC) responses from normal subjects (n = 18), patients with multiple sclerosis (MS) (n = 18), and those with glaucoma (n = 3). We then characterized the relationship between ONHC response abnormalities and performance on low-contrast visual acuity, multifocal visual-evoked potential-induced cortical responses, and average and quadrant retinal nerve fiber layer (RNFL) thicknesses, as measured by spectral-domain optical coherence tomography. RESULTS: Compared with the eyes of normal subjects, the eyes of patients with MS exhibited an increased number of abnormal or absent ONHC responses (p < 0.0001). For every 7-letter reduction in low-contrast letter acuity, there were corresponding 4.6 abnormal ONHC responses at 2.5% contrast (p < 0.0001) and 6.6 abnormalities at the 1.25% contrast level (p < 0.0001). Regarding average RNFL thickness, for each 10-mum thickness reduction, we correspondingly observed 6.8 abnormal ONHC responses (p = 0.0002). The most robust association was between RNFL thinning in the temporal quadrant and ONHC response abnormalities (p < 0.0001). CONCLUSION: Further characterization of ONHC abnormalities (those that are reversible and irreversible) may contribute to the development of novel neurotherapeutic strategies aimed at achieving neuroprotective, and perhaps even neurorestorative, effects in disorders that target the CNS in general, and MS in particular.

BACKGROUND: The King-Devick (KD) test measures the speed of rapid number naming, and is postulated to require fast eye movements, attention, language, and possibly other aspects of cognitive functions. While used in multiple sports concussion studies, it has not been applied to the field of movement disorders. METHODS: Forty-five Parkinson's disease (PD), 23 essential tremor (ET), and 65 control subjects were studied. Subjects performed two trials of reading out loud single-digit numbers separated by varying spacing on three test cards that were of different formats. The sum time of the faster trial was designated the KD score and compared across the three groups. RESULTS: PD patients had higher (worse) KD scores, with longer reading times compared to ET and control subjects (66 s vs. 49 s vs. 52 s, p < 0.001, adjusting for age and gender). No significant difference was found between ET and control (Delta = -3 s, 95% CI: -10 to 4). CONCLUSIONS: This is the first study of the King-Devick Test in Parkinson's disease. PD patients were found to have a slower rapid number naming speed compared to controls. This test may be a simple and rapid bedside tool for quantifying correlates of visual and cognitive function in Parkinson's disease.

BACKGROUND: Sports-related concussion has received increasing awareness due to short- and long-term neurologic sequelae seen among athletes. The King-Devick (K-D) test captures impairment of eye movements and other correlates of suboptimal brain function. We investigated the K-D test as a screening for concussion when administered by layperson sports parents in a cohort of amateur boxers. METHODS: The K-D test was administered pre-fight and post-fight by laypersons masked to the head trauma status of each athlete. Matches were watched over by a ringside physician and boxing trainer. Athletes with suspected head trauma received testing with the Military Acute Concussion Evaluation (MACE) by the ringside physician to determine concussion status. Athletes sustaining concussion were compared to the athletes screened using the K-D test. RESULTS: Post-fight K-D scores were lower (better) than the best baseline score (41 vs. 39.3 s, P=0.34, Wilcoxon signed-rank test), in the absence of concussion. One boxer sustained a concussion as determined by the ringside physician. This boxer was accurately identified by the layperson K-D testers due to a worsening in K-D test compared to baseline (3.2 seconds) and an increased number of errors. High levels of test-retest reliability were observed (intraclass correlation coefficient 0.90 [95% CI 0.84-0.97]). Additionally, 6 boxers who participated in multiple bouts showed no worsening of their K-D times further supporting that scores are not affected by the fatigue associated with sparring. CONCLUSION: The K-D test is a rapid sideline screening tool for concussion that can be effectively administered by non-medically trained laypersons.