Unilateral vestibular deafferentation (UVD) causes permanent asymmetry in the gain of the yaw VOR to high acceleration head impulses in guinea pigs

Vertigo and Dizziness in the Elderly

The prevalence of vertigo and dizziness in people aged more than 60 years reaches 30%, and due to aging of world population, the number of patients is rapidly increasing. The presence of dizziness in the elderly is a strong predictor of falls, which is the leading cause of accidental death in people older than 65 years. Balance disorders in the elderly constitute a major public health problem, and require an adequate diagnosis and management by trained physicians. In the elderly, common causes of vertigo may manifest differently, as patients tend to report less rotatory vertigo and more non-specific dizziness and instability than younger patients, making diagnosis more complex. In this mini review, age-related degenerative processes that affect balance are presented. Diagnostic and therapeutic approaches oriented to the specific impaired system, including visual, proprioceptive, and vestibular pathways, are proposed. In addition, presbystasis – the loss of vestibular and balance functions associated with aging – benign paroxysmal positional vertigo, and stroke (in acute syndromes) should always be considered.

Eye-head coordination in the guinea pig I. Responses to passive whole-body rotations

Vestibular reflexes act to stabilize the head and eyes in space during locomotion. Head stability is essential for postural control, whereas retinal image stability enhances visual acuity and may be essential for an animal to distinguish self-motion from that of an object in the environment. Guinea pig eye and head movements were measured during passive whole-body rotation in order to assess the efficacy of vestibular reflexes. The vestibulo-ocular reflex (VOR) produced compensatory eye movements with a latency of approximately 7 ms that compensated for 46% of head movement in the dark and only slightly more in the light (54%). Head movements, in response to abrupt body rotations, also contributed to retinal stability (21% in the dark; 25% in the light) but exhibited significant variability. Although compensatory eye velocity produced by the VOR was well correlated with head-in-space velocity, compensatory head-on-body speed and direction were variable and poorly correlated with body speed. The compensatory head movements appeared to be determined by passive biomechanical (e.g., inertial effects, initial tonus) and active mechanisms (the vestibulo-collic reflex or VCR). Chemically induced, bilateral lesions of the peripheral vestibular system abolished both compensatory head and eye movement responses.

Corticosteroids in the treatment of vestibular neuritis: a systematic review and meta-analysis

OBJECTIVE

To systematically review and meta-analyze the results of all randomized controlled trials comparing corticosteroids with placebo for the treatment of patients with vestibular neuritis.

DATA SOURCES

An electronic search was performed in MEDLINE, EMBASE, Cochrane Library, and CENTRAL databases, and then extensive hand-searching was performed for the identification of relevant studies. No time and language limitations were applied.

STUDY SELECTION

Prospective randomized controlled trials comparing corticosteroids with placebo for the treatment of patients with vestibular neuritis.

DATA EXTRACTION

Odds ratios (ORs), weighted mean differences (WMD), 95% confidence intervals (CIs), and tests for heterogeneity were reported.

DATA SYNTHESIS

Four studies were eventually identified and systematically reviewed. Meta-analysis was feasible for 3 studies. Regarding the recovery of clinical symptoms, the proportion of patients with clinical recovery at 1 month after the initiation of therapy did not differ significantly between the corticosteroids and placebo groups (OR, 1.45; 95% CI, 0.26-8.01; p = 0.67). The proportion of patients with caloric complete recovery was significantly different between the corticosteroids and placebo groups both at 1 (OR, 12.64; 95% CI, 2.6-61.52; p = 0.002; heterogeneity, p = 0.53; fixed effects model) and 12 months (OR, 3.35; 95% CI, 1.45-7.76; p = 0.005; heterogeneity, p = 0.03; random effects model) after the initiation of therapy. The caloric extent of canal paresis at 12 months after the initiation of therapy seemed to differ significantly between patients who received corticosteroids and those who received placebo (WMD, -12.15; 95% CI, -19.85 to -4.46; p < 0.05; heterogeneity, p < 0.05; random effects model).

CONCLUSION

The present systematic review and meta-analysis, based on the currently available evidence, suggests that corticosteroids improve only the caloric extent and recovery of canal paresis of patients with vestibular neuritis. At present, clinical recovery does not seem be better in patients receiving corticosteroids.