Visual height intolerance and acrophobia: distressing partners for life

[Less common, but clinically important episodic vertigo syndromes]

Die Differentialdiagnostik der selteneren, episodischen Schwindelsyndrome kann im klinischen Alltag eine Herausforderung darstellen, insbesondere wenn sie keine im Intervall messbaren Befunde in der neuro-ophthalmologischen oder -otologischen Routinediagnostik hinterlassen. Ursächlich für diese episodischen Schwindelsyndrome können physiologische Reaktionen aufgrund intersensorischer Inkongruenzen oder angeborene bzw. erworbene neuroanatomische/neurophysiologische Varianten sein, die zu vestibulären Reizsyndromen führen. In dieser Übersicht fokussieren wir auf die folgenden, aus unserer Sicht wichtigen vestibulären Syndrome: Bewegungskrankheit, Mal de Debarquement Syndrom, Visuelle Höhenintoleranz, Vestibularisparoxysmie, Zervikaler Schwindel, Episodische Ataxie Typ II und Syndrome eines dritten mobilen Fensters wie das Syndrom der Dehiszenz des superioren Bogengangs. Die Ausprägung reicht von milden Symptomen mit geringer Belastung bis hin zu schweren Krankheitsbildern mit relevanter Alltagseinschränkung. Sie können vom Kindes- oder Jugendalter bis ins Senium auftreten, teilweise mit abweichender Symptomatik. Durch gezielte Anamnese und ggf. erweiterte vestibuläre Diagnostik in einem spezialisierten Zentrum lassen sich diese Syndrome oft klar herausarbeiten und einer erfolgreichen Therapie zuführen.

Efficacy and acceptability of different interventions for acrophobia: A network meta-analysis of randomised controlled trials

BACKGROUND

Currently, different psychological interventions have shown significant efficacy in the treatment of acrophobia. However, the superiority of these individual treatments remains unclear. This network meta-analysis (NMA) aimed to investigate the efficacy, acceptability, and superiority of different existing interventions for acrophobia.

METHODS

We conducted a NMA of randomised controlled trials (RCTs) and compared the efficacy, acceptability, and superiority of different existing interventions for acrophobia.

RESULTS

In total, 17 RCTs (946 participants) were included in this study. The NMA demonstrated that virtual reality (VR) coach-delivered psychotherapy (standardised mean difference [SMD]=-2.08, 95% confidence interval [CI]: -3.22 to -0.93), in vivo exposure augmented with oppositional action (SMD=-1.66, 95% CI: -2.81 to -0.51), VR exposure therapy with 20 mg cortisol administration (SMD=-1.61, 95% CI: -3.14 to -0.09), VR based cognitive behavioural therapy (VRbasedCBT; SMD=-1.14, 95% CI: -2.22 to -0.05), and in vivo exposure (SMD=-1.02, 95% CI: -1.81 to -0.23) were significantly superior than the placebo/control interventions in improving the symptoms of patients with acrophobia. The NMA further indicated that VR coach-delivered psychotherapy was associated with the best improvement among all the 19 treatments for acrophobia. Furthermore, only VRbasedCBT (odds ratio=2.55, 95% CI: 1.09 to 5.96) was associated with higher dropout rate than the control/placebo.

LIMITATIONS

Sample heterogeneity, non-standardised assessment tools, and limited RCTs in some of the treatment arms.

CONCLUSIONS

VR coach-delivered psychotherapy could be considered as a first-line intervention for treating acrophobia. However, because of the study limitations, the overall evidence was not sufficiently strong, which warrants future studies.

Acrophobia Quantified by EEG Based on CNN Incorporating Granger Causality

The aim of this study is to quantify acrophobia and provide safety advices for high-altitude workers. Considering that acrophobia is a fuzzy quantity that cannot be accurately evaluated by conventional detection methods, we propose a comprehensive solution to quantify acrophobia. Specifically, this study simulates a virtual reality environment called High-altitude Plank Walking Challenge, which provides a safe and controlled experimental environment for subjects. Besides, a method named Granger Causality Convolutional Neural Network (GCCNN) combining convolutional neural network and Granger causality functional brain network is proposed to analyze the subjects' noninvasive scalp EEG signals. Here, the GCCNN method is used to distinguish the subjects with severe acrophobia, moderate acrophobia, and no acrophobia in a three-class classification task or no acrophobia and acrophobia in a two-class classification task. Compared with the mainstream methods, the GCCNN method achieves better classification performance, with an accuracy of 98.74% for the two-class classification task (no acrophobia versus acrophobia) and of 98.47% for the three-class classification task (no acrophobia versus moderate acrophobia versus severe acrophobia). Consequently, our proposed GCCNN method can provide more accurate quantitative results than the comparative methods, making it to be more competitive in further practical applications.

Acrophobia and visual height intolerance: advances in epidemiology and mechanisms

Historical descriptions of fear at heights date back to Chinese and Roman antiquity. Current definitions distinguish between three different states of responses to height exposure: a physiological height imbalance that results from an impaired visual control of balance, a more or less distressing visual height intolerance, and acrophobia at the severest end of the spectrum. Epidemiological studies revealed a lifetime prevalence of visual height intolerance including acrophobia in 28% of adults (32% in women; 25% in men) and 34% among prepubertal children aged 8–10 years without gender preponderance. Visual height intolerance first occurring in adulthood usually persists throughout life, whereas an early manifestation in childhood usually shows a benign course with spontaneous relief within years. A high comorbidity was found with psychiatric disorders (e.g. anxiety and depressive syndromes) and other vertigo syndromes (e.g. vestibular migraine, Menière’s disease), but not with bilateral vestibulopathy. Neurophysiological analyses of stance, gait, and eye movements revealed an anxious control of postural stability, which entails a co-contraction of anti-gravity muscles that causes a general stiffening of the whole body including the oculomotor apparatus. Visual exploration is preferably reduced to fixation of the horizon. Gait alterations are characterized by a cautious slow walking mode with reduced stride length and increased double support phases. Anxiety is the critical factor in visual height intolerance and acrophobia leading to a motor behavior that resembles an atavistic primitive reflex of feigning death. The magnitude of anxiety and neurophysiological parameters of musculoskeletal stiffening increase with increasing height. They saturate, however, at about 20 m of absolute height above ground for postural symptoms and about 40 m for anxiety (70 m in acrophobic participants). With respect to management, a differentiation should be made between behavioral recommendations for prevention and therapy of the condition. Recommendations for coping strategies target behavioral advices on visual exploration, control of posture and locomotion as well as the role of cognition. Treatment of severely afflicted persons with distressing avoidance behavior mainly relies on behavioral therapy.

A New Questionnaire for Estimating the Severity of Visual Height Intolerance and Acrophobia by a Metric Interval Scale

Aims

To construct and validate a short scale for the assessment of the severity of visual height intolerance (vHI) and acrophobia.

Methods

The questionnaire was developed from two earlier representative epidemiological studies (n = 5,529). Items were applied in a telephone survey of a representative population-based sample.

Results

A total of 1,960 persons were included. The life-time prevalence of vHI was 32.7% (f: 36.1%; m: 28.4%); 12% of these persons fulfilled the psychiatric criteria of acrophobia. Rasch analysis of 11 items on severity, symptoms, and triggers resulted in an 8-item scale with good fit to the model. The score differentiated well between persons with and without acrophobia. The distribution of the scores on the metric scale of the questionnaires of those individuals with acrophobia is separate and distinct from that of susceptibles without acrophobia, although there is some overlap.

Conclusion

Our proposed short questionnaire (vHISS, see Table 1 and Supplementary Material) allows a continuous quantification of the severity of vHI within a metric interval scale from 0 to 13. The diagnosis of acrophobia can be established by including two additional questions.