Vestibular dysfunction followed by panic disorder with agoraphobia

A case report of agoraphobia following right parietal lobe surgery: changes in functional and structural connectivities of the multimodal vestibular network

Agoraphobia is a visuo-vestibular-spatial disorder that may involve dysfunction of the vestibular network, which includes the insular and limbic cortex. We sought to study the neural correlates of this disorder in an individual who developed agoraphobia after surgical removal of a high-grade glioma located in the right parietal lobe, by assessing pre- and post-surgery connectivities in the vestibular network. The patient underwent surgical resection of the glioma located within the right supramarginal gyrus. The resection interested also portions of the superior and inferior parietal lobe. Structural and functional connectivities were assessed through magnetic resonance imaging before and 5 and 7 months after surgery. Connectivity analyses focused on a network comprising 142 spherical regions of interest (4 mm radius) associated with the vestibular cortex: 77 in the left and 65 in the right hemisphere (excluding lesioned regions). Tractography for diffusion-weighted structural data and correlation between time series for functional resting-state data were calculated for each pair of regions in order to build weighted connectivity matrices. Graph theory was applied to assess post-surgery changes in network measures, such as strength, clustering coefficient, and local efficiency. Structural connectomes after surgery showed a decrease of strength in the preserved ventral portion of the supramarginal gyrus (PFcm) and in a high order visual motion area in the right middle temporal gyrus (37dl), and decrease of the clustering coefficient and of the local efficiency in several areas of the limbic, insular cortex, parietal and frontal cortex, indicating general disconnection of the vestibular network. Functional connectivity analysis showed both a decrease in connectivity metrics, mainly in high-order visual areas and in the parietal cortex, and an increase in connectivity metrics, mainly in the precuneus, parietal and frontal opercula, limbic, and insular cortex. This post-surgery reorganization of the vestibular network is compatible with altered processing of visuo-vestibular-spatial information, yielding agoraphobia symptoms. Specifically, post-surgical functional increases of clustering coefficient and local efficiency in the anterior insula and in the cingulate cortex might indicate a more predominant role of these areas within the vestibular network, which could be predictive of the fear and avoiding behavior characterizing agoraphobia.

Stabilometric Biofeedback Training in Cognitive and Affective Function Improvement. Contribution of the Russian Scientific School. Part II

This review is the second part of the critical analysis of recent papers of Russian and other authors devoted to the study of the stabilometric parameters in postural control biofeedback training and rehabilitation, associated with psychological functions. The review presents the studies of postural control features in chronic pain syndrome, chronic fatigue syndrome, Parkinson's disease, multiple sclerosis, and depression. The leading role of Russian researchers in the development and application of stabilometric biofeedback in the training of optimal functioning, rehabilitation, and correction of neurological disorders is noted. The paradigm of stabilometric biofeedback training of the cognitive and affective functions is offered.

Altered Insular and Occipital Responses to Simulated Vertical Self-Motion in Patients with Persistent Postural-Perceptual Dizziness

BACKGROUND

Persistent postural-perceptual dizziness (PPPD) is a common functional vestibular disorder characterized by persistent symptoms of non-vertiginous dizziness and unsteadiness that are exacerbated by upright posture, self-motion, and exposure to complex or moving visual stimuli. Recent physiologic and neuroimaging data suggest that greater reliance on visual cues for postural control (as opposed to vestibular cues-a phenomenon termed visual dependence) and dysfunction in central visuo-vestibular networks may be important pathophysiologic mechanisms underlying PPPD. Dysfunctions are thought to involve insular regions that encode recognition of the visual effects of motion in the gravitational field.

METHODS

We tested for altered activity in vestibular and visual cortices during self-motion simulation obtained via a visual virtual-reality rollercoaster stimulation using functional magnetic resonance imaging in 15 patients with PPPD and 15 healthy controls (HCs). We compared between groups differences in brain responses to simulated displacements in vertical vs horizontal directions and correlated the difference in directional responses with dizziness handicap in patients with PPPD.

RESULTS

HCs showed increased activity in the anterior bank of the central insular sulcus during vertical relative to horizontal motion, which was not seen in patients with PPPD. However, for the same comparison, dizziness handicap correlated positively with activity in the visual cortex (V1, V2, and V3) in patients with PPPD.

CONCLUSION

We provide novel insight into the pathophysiologic mechanisms underlying PPPD, including functional alterations in brain processes that affect balance control and reweighting of space-motion inputs to favor visual cues. For patients with PPPD, difficulties using visual data to discern the effects of gravity on self-motion may adversely affect balance control, particularly for individuals who simultaneously rely too heavily on visual stimuli. In addition, increased activity in the visual cortex, which correlated with severity of dizziness handicap, may be a neural correlate of visual dependence.

Behavioral models for anxiety and multisensory integration in animals and humans

Complaints related to dizziness, balance problems and spatial disorientation in psychiatry have seldom been considered as a possible manifestation of a distorted multisensory integrative ability. Several kinds of mismatches among simultaneous sensory information are encountered in everyday life but despite these, the central nervous system usually manages to update the internal representation of the body in the surrounding space. In some cases, a sensory mismatch may elicit an erroneous perception of the body in space, resulting in anxiety, dizziness and balance problems. As vestibular system dysfunction leads to dizziness and disorientation, it has been hypothesized that a peripheral vestibular abnormality could explain the presence of certain symptoms related to sensory mismatches in anxiety disorders. Several studies tried to find a link between panic disorder with or without agoraphobia and vestibular system dysfunction. Yet, even though some vestibular abnormalities have been demonstrated in these patients, it is difficult to demonstrate a cause-and-effect relationship between panic disorder and vestibular dysfunction. However, this does not rule out a possible influence of anxiety on normal vestibular function. The study of the relation between vestibular system and anxiety has to take into account that the vestibular system has three main functions: to maintain equilibrium through the vestibular spinal reflexes; to stabilize the visualization of the world through the vestibular-ocular reflex; to contribute to perception and orientation in space. We will review different studies in humans, which have particularly paid attention to the third function and its relation to anxiety. Animal experiments offer possibilities to more precisely analyze the different parameters underlying the behavioral results, as well as possible pharmacological actions on them. Two attempts have been made by our group to model, in mice, the preceding human data on integrated functional sensory relations of the body to space in anxiety disorders: the rotating beam and the rotating tunnel. We summarize here the main results obtained.

Space and motion discomfort and abnormal balance control in patients with anxiety disorders

OBJECTIVE

Previous research suggested that panic disorder with agoraphobia is associated with abnormalities on vestibular and balance function tests. The purpose of this study was to further examine psychiatric correlates of vestibular/balance dysfunction in patients with anxiety disorders and the specific nature of the correlated vestibular abnormalities. The psychiatric variables considered included anxiety disorder versus normal control status, panic disorder versus non-panic anxiety disorder diagnosis, presence or absence of comorbid fear of heights, and degree of space and motion discomfort (SMD). The role of anxiety responses to vestibular testing was also re-examined.

METHODS

104 subjects were recruited: 29 psychiatrically normal individuals and 75 psychiatric patients with anxiety disorders. Anxiety patients were assigned to four subgroups depending on whether or not they had panic disorder and comorbid fear of heights. SMD and anxiety responses were measured by questionnaires. Subjects were examined for abnormal unilateral vestibular hypofunction on caloric testing indicative of peripheral vestibular dysfunction, asymmetric responses on rotational testing as an indicator of an ongoing vestibular imbalance and balance function using Equitest dynamic posturography as an indicator of balance control. Logistic regression was used to establish the association between the psychiatric variables and vestibular or balance test abnormalities.

RESULTS

Rotational test results were not significantly related to any of the psychiatric variables. The presence of either panic attacks or fear of heights increased the probability of having caloric hypofunction in a non-additive fashion. SMD and anxiety responses were independently associated with abnormal balance. Among specific posturography conditions, the association with SMD was significant for a condition that involved the balance platform tilting codirectionally with body sway, suggesting an abnormal dependence on somatosensory cues in the control of balance.

CONCLUSION

In patients with anxiety disorders, higher SMD is indicative of somatosensory dependence in the control of balance. The absence of both panic and fear of heights reduces the probability of having peripheral vestibular dysfunction. Future research should examine if vestibular rehabilitation can be of value for patients with anxiety disorders complicated by SMD.

Stress and symptoms of Menière's disease: a time-series analysis

Meniere's disease is an inner ear disease in which the symptom cluster of hearing loss, tinnitus, and dizziness is found along with attacks of vertigo and nausea. In this study, 20 subjects diagnosed with Meniere's disease completed daily measures of stress and symptoms during periods ranging between 45 and 351 days (M = 193.5). Data were analyzed by means of time-series analysis (ARIMA), and the temporal associations were investigated by lagged correlations. The results showed concurrent (same day) associations between stress and symptoms, but individual differences were found regarding which symptoms were associated with stress. Although stress is linked with symptom perception, this study does not support the role of stress as a precursor of symptoms in Meniere's disease.

Surface dependence: a balance control strategy in panic disorder with agoraphobia

OBJECTIVE

Previous studies have reported vestibular dysfunction and impaired balance in patients with agoraphobia. Vestibular dysfunction may lead to an information processing strategy focusing on spatial stimuli from two nonvestibular sensory channels, vision and proprioception. This nonvestibular balance control strategy may in turn lead to discomfort in situations involving inadequate visual or proprioceptive spatial cues (space and motion discomfort). The objective of this study was to examine sensory integration of spatial information in agoraphobia. Because of previous findings that space and motion discomfort and vestibular dysfunction are common in agoraphobia, we hypothesized that agoraphobics would use a nonvestibular balance control strategy.

METHOD

Using computerized dynamic posturography, we examined balance performance in patients with panic disorder with agoraphobia, uncomplicated panic disorder, nonpanic anxiety disorders, and depression without anxiety, as well as healthy subjects for comparison. The posturography procedure included six sensory conditions in which visual and proprioceptive balance information was manipulated experimentally by permutations of sway-referencing the support surface or the visual surround or by having patients close their eyes.

RESULTS

The agoraphobics had impaired balance when proprioceptive balance information was minimized by sway-referencing the support surface (p < 0.02). This pattern, called surface dependence, tended to be more pronounced in agoraphobics who reported space and motion discomfort, including fear of heights or boats.

CONCLUSION

Agoraphobics rely on proprioceptive cues for maintenance of upright balance. This strategy may lead to intolerance of situations characterized by unstable support.

A longitudinal study of symptoms, anxiety and subjective well-being in patients with vertigo

In a prospective longitudinal study of the relationship between symptoms and anxiety in people with vertigo, 101 patients were evaluated on two occasions separated by a 7 month interval. At Time 1 the age, gender, vertigo type, duration of illness, medication, and audiovestibular test results of patients were recorded, and they completed questionnaires assessing handicap, emotional distress, predisposition to anxiety, and symptoms indicative of vertigo and of somatic anxiety. These questionnaires were re-administered at Time 2, and patients also indicated whether their vertigo was more or less severe than at Time 1. Although vertiginous symptoms at Time 2 were generally mild and intermittent, they were associated with significant handicap. Reported symptoms of somatic anxiety and arousal at Time 1 proved to be the only longitudinal predictors of perceived change in vertigo severity over the 7 month period.

Phobic postural vertigo: a first follow-up

Seventy-eight patients with phobic postural vertigo (PPV) and 17 patients with psychogenic disorder of stance and gait (PSG) were asked to evaluate their condition 6 months to 5.5 years after their original referral and short-term psychotherapy. Two results seem most important: (1) PPV had a favorable course with a 72% improvement rate (22% of patients becoming symptom free), whereas the majority of patients with PSG (52%) remained unchanged; (2) the majority of patients with PPV experienced complete remission or considerable improvement even if their condition had lasted between 1 and 20 years prior to diagnosis. Complete remission of PSG was observed only if the disorder has been present less than 4 months; there was no improvement if it had lasted longer than 2 years. PPV can be defined as a distinct clinical entity with a relatively benign course. It can be reliably diagnosed on the basis of typical features.

Psychiatric morbidity in patients with peripheral vestibular disorder: a clinical and neuro-otological study

This study reports the psychiatric morbidity in 54 patients with objective evidence of peripheral vestibular disorder seen three to five years after their original referral. A third of the patients were free from vestibular symptoms at follow up and a further third had experienced some improvement. Two thirds of the patients had experienced psychiatric symptoms during this period, although only 50% were rated above the cut off point for significant psychiatric disturbance when interviewed. Panic disorder with or without agoraphobia and major depression were the commonest psychiatric diagnoses. Patients with classical "labyrinthine" symptoms had a more severe canal paresis than the rest, but the degree of the abnormalities in the neuro-otological tests was unrelated to outcome or to psychiatric morbidity. On the other hand, there was a significant correlation between the presence of vestibular symptoms and psychiatric morbidity, which in turn correlated with measures of anxiety, perceived stress and previous psychiatric illness.