Resting in darkness improves downbeat nystagmus: evidence from an observational study.

Resting in an upright position during daytime decreases downbeat nystagmus (DBN). When measured in brightness only, that is, without intermitting exposure to darkness, it does not make a significant difference whether patients have previously rested in brightness or in darkness. In real-world scenarios, people are often exposed to brightness and darkness intermittently. The aim of this study was to analyze whether resting in brightness or resting in darkness was associated with a lower post-resting DBN after intermitting exposures to brightness and darkness. Eight patients were recorded with three-dimensional video-oculography in brightness and darkness conditions, each following two 2-h resting intervals under either brightness or darkness resting conditions. The dependent variable was DBN intensity, measured in mean slow phase velocity. A repeated measures ANOVA with the factors measurement condition (brightness vs. darkness), resting condition (brightness vs. darkness), and time (after first vs. second resting interval) showed a significant effect for the factor resting condition, where previous resting in darkness was associated with a significantly lower DBN relative to previous resting in brightness (P < 0.01). The clinical relevance is to advise patients with DBN to rest in darkness.

A randomised double-blind, cross-over trial of 4-aminopyridine for downbeat nystagmus--effects on slowphase eye velocity, postural stability, locomotion and symptoms.

OBJECTIVE: The effects of 4-aminopyridine (4-AP) on downbeat nystagmus (DBN) were analysed in terms of slow-phase velocity (SPV), stance, locomotion, visual acuity (VA), patient satisfaction and side effects using standardised questionnaires. METHODS: Twenty-seven patients with DBN received 5 mg 4-AP four times a day or placebo for 3 days and 10 mg 4-AP four times a day or placebo for 4 days. Recordings were done before the first, 60 min after the first and 60 min after the last drug administration. RESULTS: SPV decreased from 2.42 deg/s at baseline to 1.38 deg/s with 5 mg 4-AP and to 2.03 deg/s with 10 mg 4-AP (p<0.05; post hoc: 5 mg 4-AP: p=0.04). The rate of responders was 57%. Increasing age correlated with a 4-AP-related decrease in SPV (p<0.05). Patients improved in the 'get-up-and-go test' with 4-AP (p<0.001; post hoc: 5 mg: p=0.025; 10 mg: p<0.001). Tandem-walk time (both p<0.01) and tandem-walk error (4-AP: p=0.054; placebo: p=0.059) improved under 4-AP and placebo. Posturography showed that some patients improved with the 5 mg 4-AP dose, particularly older patients. Near VA increased from 0.59 at baseline to 0.66 with 5 mg 4-AP (p<0.05). Patients with idiopathic DBN had the greatest benefit from 4-AP. There were no differences between 4-AP and placebo regarding patient satisfaction and side effects. CONCLUSIONS: 4-AP reduced SPV of DBN, improved near VA and some locomotor parameters. 4-AP is a useful medication for DBN syndrome, older patients in particular benefit from the effects of 5 mg 4-AP on nystagmus and postural stability.

Migraine-related vertigo and somatoform vertigo frequently occur in children and are often associated.

Migraine-related syndromes are a common cause of episodic vertigo and dizziness in children. Somatoform vertigo (SV) is an important cause of chronic dizziness, especially in adolescents. Our aim was to elucidate the comorbidity of migraine and SV. Three diagnostic groups were defined: migraine-related vertigo (MRV), SV, and combined migraine-related and SV (MSV). A retrospective analysis was performed on patient data (demographics, diagnosis, neuro-orthoptic and neurologic status, and results of vestibular and balance testing) from 168 patients who were presented to the German Center for Vertigo and Balance Disorders (IFB) over a 2.5-year period. Mean age of patients was 12 ± 4 years (range: 1.4 to 18 years). The most frequent diagnosis was MRV (28%), followed by MSV (19%) and SV (14%). MSV occurred most frequently in adolescent girls (25%). MRV was the most common cause of dizziness in our cohort. MSV ranked second overall but ranked first in adolescent girls, followed by isolated SV. SV was most prevalent in adolescent girls. MRV, MSV, and SV account for about 60% of diagnoses established in our tertiary referral center. Competent care of childhood migraine should include skill in detecting both the clinical symptoms of vertigo and overlapping somatoform symptoms.

Comparison of 10-mg doses of 4-aminopyridine and 3,4-diaminopyridine for the treatment of downbeat nystagmus.

OBJECTIVE: Animal experiments have demonstrated that aminopyridines increase Purkinje cell excitability, and in clinical studies, 4-aminopyridine (4-AP) and 3,4-diaminopyridine (3,4-DAP) improved downbeat nystagmus. In this double-blind, prospective, crossover study, the effects of equivalent doses of 4-AP and 3,4-DAP on the slow-phase velocity (SPV) of downbeat nystagmus were compared. METHODS: Eight patients with downbeat nystagmus due to different etiologies (cerebellar degeneration [n = 1], bilateral vestibulopathy [n = 1], bilateral vestibulopathy and cerebellar degeneration [n = 1], Arnold-Chiari I malformation and cerebellar ataxia [n = 1], cryptogenic cerebellar ataxia [n = 4]) were included. They were randomly assigned to receiving a single capsule of 10 mg of 3,4-DAP or 4-AP followed by 6 days with no medication. One week later, the treatment was switched, that is, 1 single capsule (10 mg) of the other agent. Recordings with 3-dimensional video-oculography were performed before and 45 and 90 minutes after drug administration. RESULTS: Both medications had a significant effect throughout time (pre vs post 45 vs post 90) (F() = 8.876; P < 0.01). Following the administration of 3,4-DAP, mean slow velocity decreased from -5.68°/s (pre) to -3.29°/s (post 45) to -2.96°/s (post 90) (pre vs post 45/post 90 P < 0.01). In 4-AP, the mean SPV decreased from -6.04°/s (pre) to -1.58°/s (post 45) to -1.21°/s (post 90) (pre vs post 45/post 90 P < 0.00001). Both after 45 and after 90, the mean SPVs were significantly lower for 4-AP than for 3,4-DAP (P < 0.05). None of the patients reported serious side effects. CONCLUSION: Based on these results, 10-mg doses of 4-AP lead to a more pronounced decrease of the SPV of downbeat nystagmus than do equivalent doses of 3,4-DAP.

Evaluation of a community-based intervention to enhance road safety.

A total of 300 motorists were recruited at public places to answer a self-report questionnaire on a new community-based intervention to enhance road safety. The intervention consisted of a speed-displaying device that was mounted next to the road and was visible to both motorists and the public. The device gives feedback about the current speed of the motorist. The majority of motorists believed these devices influenced compliance with the speed limit. They indicated they approached locations with these devices more slowly than similar locations without such devices. Moreover, they slowed down if they were going faster than the speed limit. They also said that their reaction to the devices was not influenced by whether they were driving in a community where they had friends or in a community where nobody knew them. These results were consistent across gender, age, levels of education, and professions.

The intensity of downbeat nystagmus during daytime.

On the basis of reports by patients with downbeat nystagmus (DBN) that their symptoms were worse during the morning but better during the daytime, we investigated whether the intensity of DBN changes during the daytime. DBN was measured at 9 am, 11 am, and 1 pm. The mean peak slow phase velocity (MPSPV) of DBN was determined in different eye positions, with and without fixation, as well as in three different body positions: sitting upright, lying supine with the nose up, and lying prone with the nose down. Twelve patients with DBN either due to cerebellar degeneration or of idiopathic etiology were examined. The major findings of this study were as follows. First, the intensity of DBN significantly decreased during the daytime. When measured in the sitting upright position and primary eye position, MPSPV decreased from 4.32 deg/sec (+/-SEM 1.02) at 9 am to 2.12 deg/sec (+/- 0.5) at 11 am (P < 0.01) and stayed constant around 1.93 deg/sec (+/- 0.57) at 1 pm (P < 0.01 from 9 am to 1 pm) and 2.08 deg/sec (+/- 0.75) at 3 pm (P < 0.01 from 9 am to 3 pm). Second, this change did not depend on fixation during the measurements. Third, this effect was not influenced by the eye position during the measurements (upward, downward, or straight ahead). Our data show that the intensity of DBN decreases during the daytime. This decrease correlates with the symptoms of the patients. This change during daytime did not depend on visual fixation. Another possible mechanism is the modulation of DBN by head position relative to gravity, that is, by otolith input. This should be evaluated in further studies.

Downbeat nystagmus caused by a paramedian ponto-medullary lesion.

Downbeat nystagmus (DBN) is rarely caused by lesions in sites other than the cerebellar (para-)floccular lobe. We describe a case of DBN secondary to a hemorrhaged venous cavernoma at the pontomedullary junction. This case provides new insights into the neuro-anatomical substrate of DBN. We propose that DBN arises from lesions in a brainstem-cerebellar feedback loop, which comprises cells of the pontine paramedian tract (PMT).

Central compensation of deviated subjective visual vertical in Wallenberg's syndrome.

The central compensation of vestibular tonus imbalance due to unilateral peripheral vestibular lesions has been repeatedly documented. Little is known, however, about the central compensation of vestibular tonus imbalance due to central lesions. Dorsolateral medullary infarctions (Wallenberg's syndrome) typically cause a central vestibular tonus imbalance in the roll plane with deviations of perceived verticality and ipsiversive body lateropulsion. The course of normalisation of the tilts of subjective visual vertical (SVV) in 50 patients who had acute Wallenberg's syndrome were retrospectively compared with that in 50 patients with acute vestibular neuritis. The initial displacement of SVV was 9.8 degrees in Wallenberg's syndrome and 7 degrees in vestibular neuritis. The deviation of SVV significantly decreased over time within days to weeks in both groups. This finding shows that the time courses of the central compensation for dorsolateral medullary infarctions and peripheral vestibular lesions are similar.