Otolithic functions in patients with residual dizziness after successful repositioning manoeuvres for unilateral posterior canal BPPV.

OBJECTIVE: To evaluate otolithic functions in patients with residual dizziness after successful canalith repositioning procedures (CRPs) for unilateral posterior canal benign paroxysmal positional vertigo (BPPV), and to investigate possible risk factors. METHODS: This case-control observational study included healthy controls and patients with residual dizziness after improvement following CRP for BPPV. All participants were subjected to full history taking, otoscopy, audiological basic evaluation, Dix-Hallpike test to search for posterior canal BPPV, residual dizziness screening, and vestibular evoked myogenic potential (VEMP) testing. Between-group differences were assessed and possible factors associated with residual dizziness were identified by univariate analysis. RESULTS: A total of 50 patients with residual dizziness (mean age, 56.53 ± 7.46 years [29 female: 21 male]) and 50 healthy controls (mean age, 58.13 ± 7.57 years [20 female: 30 male]) were included. A significant difference in VEMP latencies was found between the patient and control group (delayed in the patient group), with no significant between-group difference in amplitude in both ears. Aging, female sex, long duration of BPPV, number of CRPs, cervical VEMP and ocular VEMP abnormalities, and winter onset, were significantly associated with the risk of residual dizziness. CONCLUSIONS: Residual dizziness is a frequent sequel of BPPV that may relate to otolithic dysfunction. VEMP changes were revealed in the form of delayed latencies.

Introduction to the assessment and management of persistent postural-perceptual dizziness.

OBJECTIVE: Persistent postural-perceptual dizziness classifies patients with chronic dizziness, often triggered by an acute episode of vestibular dysfunction or threat to balance. Unsteadiness and spatial disorientation vary in intensity but persist for over three months, exacerbated by complex visual environments. METHOD: Literature suggests diagnosis relies on a clinical history of persistent subjective dizziness and normal vestibular and neurological examination findings. Behavioural diagnostic biomarkers have been proposed, to facilitate diagnosis. RESULTS: Research has focused on understanding the neural mechanisms that underpin this perceptual disorder, with imaging data supporting altered connectivity between neural brain networks that process vision, motion and emotion. Behavioural research identified the perceptual and motor responses to a heightened perception of imbalance. CONCLUSION: Management utilises head and body motion detection, and downregulation of visual motion excitability, reducing postural hypervigilance and anxiety. Combinations of physical and cognitive therapies, with antidepressant medications, help if the condition is associated with mood disorder.

TMS of the left primary motor cortex improves tremor intensity and postural control in primary orthostatic tremor.

A ponto-cerebello-thalamo-cortical network is the pathophysiological correlate of primary orthostatic tremor. Affected patients often do not respond satisfactorily to pharmacological treatment. Consequently, the objective of the current study was to examine the effects of a non-invasive neuromodulation by theta burst repetitive transcranial magnetic stimulation (rTMS) of the left primary motor cortex (M1) and dorsal medial frontal cortex (dMFC) on tremor frequency, intensity, sway path and subjective postural stability in primary orthostatic tremor. In a cross-over design, eight patients (mean age 70.2 ± 5.4 years, 4 female) with a primary orthostatic tremor received either rTMS of the left M1 leg area or the dMFC at the first study session, followed by the other condition (dMFC or M1 respectively) at the second study session 30 days later. Tremor frequency and intensity were quantified by surface electromyography of lower leg muscles and total sway path by posturography (foam rubber with eyes open) before and after each rTMS session. Patients subjectively rated postural stability on the posturography platform following each rTMS treatment. We found that tremor frequency did not change significantly with M1- or dMFC-stimulation. However, tremor intensity was lower after M1- but not dMFC-stimulation (p = 0.033/ p = 0.339). The sway path decreased markedly after M1-stimulation (p = 0.0005) and dMFC-stimulation (p = 0.023) compared to baseline. Accordingly, patients indicated a better subjective feeling of postural stability both with M1-rTMS (p = 0.007) and dMFC-rTMS (p = 0.01). In conclusion, non-invasive neuromodulation particularly of the M1 area can improve postural control and tremor intensity in primary orthostatic tremor by interference with the tremor network.

Vestibular migraine: an update.

PURPOSE OF REVIEW: We performed a narrative review of the recent findings in epidemiology, clinical presentation, mechanisms and treatment of vestibular migraine. RECENT FINDINGS: Vestibular migraine is an underdiagnosed condition that has a high prevalence among general, headache and neuro-otology clinics. Vestibular migraine has a bimodal presentation probably associated with a hormonal component in women. These patients could have a complex clinical phenotype including concomitant autonomic, inflammatory or connective tissue conditions that have a higher prevalence of psychological symptoms, which may mistakenly lead to a diagnosis of a functional neurological disorder. A high proportion of patients with postural perceptual persistent dizziness have a migraine phenotype. Independently of the clinical presentation and past medical history, patients with the vestibular migraine phenotype can respond to regular migraine preventive treatments, including those targeting the calcitonin gene-related peptide pathways. SUMMARY: Vestibular migraine is an underdiagnosed migraine phenotype that shares the pathophysiological mechanisms of migraine, with growing interest in recent years. A thorough anamnesis is essential to increase sensitivity in patients with unknown cause of dizziness and migraine treatment should be considered (see supplemental video-abstract).

Effects of the Kahramanmaras, Turkey 2023 earthquakes on balance perception, dizziness and post-traumatic stress: A relational screening model between subjective balance problems and post-traumatic stress.

OBJECTIVE: The aim of the present study was to investigate the effects of the February 6, 2023, earthquakes in Turkey and recurrent aftershocks on balance and post-traumatic stress in surviving victims. METHODS: Our study included 1004 participants aged 18-65 years who were exposed to the February 6 earthquakes and aftershocks in Turkey. After obtaining online consent from all participants, the Vertigo Symptom Scale (VSS), the Dizziness Handicap Index (DHI), and the Posttraumatic Post-Traumatic Disorder Checklist Scale (PCL-5) were administered online, and the interactions between the variable sets were examined using a correlational screening model. RESULTS: As a result of the structural equation model established with the observed variables, it was found that VSS total scores had a statistically significant positive effect on PCL-5 (ß1 = 0.56; p = 0.001 < 0.05). In addition, statistically significant positive high-level correlations were found between VSS and DHI (covVSS-DHI = 0.71), and a positive low level correlation with the number of days with dizziness (covVSS-number of days with dizziness = 0.34), and a positive low level correlation with frequency of days with dizziness (covVSS-frequency of days with dizziness = 0.37). A statistically significant positive low-level relationship was found between DHI and the number of days with dizziness (covDHI-number of days with dizziness = 0.34) and a positive low-level correlation between DHI and the frequency of days with dizziness (covDHI-frequency of days with dizziness = 0.29). CONCLUSION: The structural equation modeling analysis showed that post-traumatic stress disorder had a significant effect on balance and dizziness.

Visual and vestibular motion perception in persistent postural-perceptual dizziness (PPPD).

Persistent postural-perceptual dizziness (PPPD) is a chronic disorder of perceived unsteadiness. Symptoms can be exacerbated in visually complex stationary or moving environment. Visual dependence and increased motion sensitivity are predictors for PPPD but its pathophysiology remains unknown. We hypothesized an abnormal sensory-perceptual scaling mechanism in PPPD and tested visual- and vestibular perceptional thresholds in 32 patients and 28 age-matched healthy control subjects (HC). All participants showed normal vestibular function tests on quantitative testing. Visual motion coherence thresholds were assessed by random dot kinetomatograms. Vestibular perceptional thresholds of egomotion were assessed by binaural galvanic vestibular stimulation (GVS) and passive chair rotation around an earth-vertical axis. Chair rotation trials were contrasted with no-motion (sham) stimulus trials. Mean thresholds of visual motion perception were higher in patients compared to HC. The perception threshold of GVS was lower in patients but the threshold of correctly perceived egomotion during chair rotation did not differ. Interestingly, the number of trials with correct perception in the no-motion condition increased with the threshold of correct responses for rotatory egomotion in patients. Unlike expected, PPPD patients required more coherently moving random dots than HC to perceive visual motion. A poorer complex visual motion recognition, e.g., traffic visual stimuli, may increase anxiety and levels of uncertainty as visuomotor reactions might occur delayed. The vestibular rotatory perception threshold predicted the probability of making false assignments in the sham condition in PPPD, i.e., patients who readily recognize the correct egomotion direction are prone to perceive egomotion in the no-motion condition. As this relation was not found in healthy subjects, it may reflect an abnormal sensory-perceptual scaling feature of PPPD.

Sense of direction in vestibular disorders.

BACKGROUND: Our sense of direction (SOD) ability relies on the sensory integration of both visual information and self-motion cues from the proprioceptive and vestibular systems. Here, we assess how dysfunction of the vestibular system impacts perceived SOD in varying vestibular disorders, and secondly, we explore the effects of dizziness, migraine and psychological symptoms on SOD ability in patient and control groups. METHODS: 87 patients with vestibular disorder and 69 control subjects were assessed with validated symptom and SOD questionnaires (Santa Barbara Sense of Direction scale and the Object Perspective test). RESULTS: While patients with vestibular disorders performed significantly worse than controls at the group level, only central and functional disorders (vestibular migraine and persistent postural perceptual dizziness), not peripheral disorders (benign-paroxysmal positional vertigo, bilateral vestibular failure and Meniere's disease) showed significant differences compared to controls on the level of individual vestibular groups. Additionally, orientational abilities associated strongly with spatial anxiety and showed clear separation from general dizziness and psychological factors in both patient and control groups. CONCLUSIONS: SOD appears to be less affected by peripheral vestibular dysfunction than by functional and/or central diagnoses, indicating that higher level disruptions to central vestibular processing networks may impact SOD more than reductions in sensory peripheral inputs. Additionally, spatial anxiety is highly associated with orientational abilities in both patients and control subjects.

Persistent postural-perceptual dizziness: A functional neuro-otologic disorder.

Persistent postural-perceptual dizziness (PPPD) is a functional neuro-otologic disorder that is the most frequent cause of chronic vestibular syndrome. The core vestibular symptoms include dizziness, unsteadiness, and non-spinning vertigo, which are exacerbated by an upright posture or walking, active or passive motion, and exposure to moving or complex visual stimuli. PPPD is mostly precipitated by acute or episodic vestibular diseases; however, its symptoms cannot be accounted for by its precipitants. PPPD is not a diagnosis of exclusion, but may coexist with other structural diseases. Thus, when diagnosing PPPD, the patient's symptoms must be explained by PPPD alone or by PPPD in combination with a structural illness. PPPD is most frequently observed at approximately 50 years of age, with a female predominance. Conventional vestibular tests do not reveal any specific signs of PPPD. However, the head roll-tilt subjective visual vertical test and gaze stability test after exposure to moving visual stimuli may detect the characteristic features of PPPD, that is, somatosensory- and visually-dependent spatial orientation, respectively. Therefore, these tests could be used as diagnostic tools for PPPD. Regarding the pathophysiology of PPPD, neuroimaging studies suggest shifts in interactions among visuo-vestibular, sensorimotor, and emotional networks, where visual inputs dominate over vestibular inputs. Postural control also shifts, leading to the stiffening of the lower body. To treat PPPD, selective serotonin reuptake inhibitors/serotonin noradrenaline reuptake inhibitors, vestibular rehabilitation, and cognitive behavioral therapy are used alone or in combination.

Post-stroke dizziness, depression and anxiety.

OBJECTIVE: Vestibular and psychiatric disorders are very closely related. Previous research shows that the discomfort and dysfunction caused by dizziness in patients can affect psychological processes, leading to anxiety and depression, and the irritation of anxiety and depression can aggravate the discomfort of dizziness. But the causal relationship between dizziness in the recovery period of stroke and Post-stroke depression (PSD) / Post-stroke anxiety (PSA) is not clear. Identifying the causal relationship between them can enable us to conduct more targeted treatments. METHODS: We review the epidemiology and relationship of dizziness, anxiety, and depression, along with the related neuroanatomical basis. We also review the pathophysiology of dizziness after stroke, vestibular function of patients experiencing dizziness, and the causes and mechanisms of PSD and PSA. We attempt to explore the possible relationship between post-stroke dizziness and PSD and PSA. CONCLUSION: The treatment approach for post-stroke dizziness depends on its underlying cause. If the dizziness is a result of PSD and PSA, addressing these psychological factors may alleviate the dizziness. This can be achieved through targeted treatments for PSD and PSA, such as psychotherapy, antidepressants, or anxiolytics, which could indirectly improve dizziness symptoms. Conversely, if PSA and PSD are secondary to vestibular dysfunction caused by stroke, a thorough vestibular function assessment is crucial. Identifying the extent of vestibular impairment allows for tailored interventions. These could include vestibular rehabilitation therapy and medication aimed at vestibular restoration. By improving vestibular function, secondary symptoms like anxiety and depression may also be mitigated.

Effect of vestibular rehabilitation games in patients with persistent postural perceptual dizziness and its relation to anxiety and depression: prospective study.

PURPOSE: To evaluate the efficacy of vestibular rehabilitation therapy (VRT) for management of patients with persistent postural perceptual dizziness (PPPD) utilizing subjective and objectives outcome measures and to study the effect of degree of both anxiety and depression in patients on the response of vestibular rehabilitation therapy. METHODS: Thirty-three PPPD patients participated in this study. Selection of patients was based on the diagnostic criteria for PPPD stated by Barany society in the International Classification of Vestibular Disorders (2017). Every patient was subjected to history taking, anxiety and depression assessment, Arabic version of Dizziness Handicap Inventory (DHI), and sensory organization test (SOT). All patients received vestibular rehabilitations therapy. Assessment of VRT outcome was conducted after 6 weeks of VRT. RESULTS: The mean patients' age was 40.9 ± 16.3 years, and nearly equal gender distribution. Vestibular migraine was the most precipitating condition (24.2%) in patients with PPPD. (39.4%) of patients had abnormal scores of anxiety and depression tests, all patients had from moderate to severe degrees of handicap caused by dizziness as measured by DHI, most of patients had abnormal findings in all conditions of SOT. After vestibular rehabilitation therapy, DHI and SOT scores showed significant improvement after VRT. More improvement was found among the group with no anxiety and depression. CONCLUSION: VRT were effective in improving balance abnormalities in patients with PPPD evidenced by subjectively by DHI scores and objectively by SOT results. PPPD patients with concomitant psychiatric disorders; anxiety and depression experienced the least degree of improvement.

Impact of subjective dizziness on motor and non-motor symptoms in patients with early stages of Parkinson's disease.

Clinicians sometimes encounter patients with Parkinson's disease complaining of dizziness in real clinical settings. We sought to identify the relationship between self-perceived dizziness and motor or non-motor symptoms, especially in Parkinsonian patients in the early stages. Eight-six patients with less than five years of Parkinson's disease duration were recruited. We used the dizziness handicap inventory to access self-reported dizziness in patients with early Parkinson's disease. Parkinsonian motor symptoms such as postural instability and gait difficulty and non-motor features for global cognitive function, depressive mood, anxiety state, fatigue state, and autonomic dysfunction were measured using representative scales. Linear regression analysis demonstrated that the dizziness handicap inventory score was significantly related to postural instability and gait difficulty, anxiety, gastrointestinal, and cardiovascular domain of dysautonomia. In addition, the dizziness handicap inventory score was positively correlated with scores for postural instability and gait difficulty, anxiety, gastrointestinal, and cardiovascular dysautonomia. We found that self-reported dizziness was highly linked to postural instability and gait difficulty, anxiety, gastrointestinal and cardiovascular dysfunctions in patients with early Parkinson's disease. Further follow-up studies on the association between dizziness and the pathophysiology of Parkinson's disease are needed.

Imbalance and dizziness caused by unilateral vestibular schwannomas correlate with vestibulo-ocular reflex precision and bias.

Imbalance and dizziness are disabling symptoms for many patients with vestibular schwannomas (VS) but symptom severity typically does not correlate with the vestibulo-ocular reflex (VOR) amplitude-based metrics used to assess peripheral vestibular damage. In this study, we tested the hypothesis that imbalance and dizziness in patients with VS relate to VOR metrics that are not based on response amplitude. Twenty-four patients with unilateral, sporadic VS tumors were studied, and objective (balance) and subjective (dizziness) vestibular dysfunction was quantified. The VOR was tested using two yaw-axis motion stimuli, low-frequency en-bloc sinusoidal, and high-frequency head-on-body impulsive rotations. Imbalance correlated with VOR precision (the inverse of the trial-to-trial variability) and with low-frequency VOR dynamics (quantified with the time constant), and these two metrics were also strongly correlated. Dizziness correlated with the VOR bias caused by an imbalance in static central vestibular tone, but not with dynamic VOR metrics. VOR accuracy (mean response amplitude relative to the ideal response) was not correlated with the severity of imbalance or dizziness or with measures of VOR precision or time constant. Imbalance in patients with VS, therefore, scales with VOR precision and time constant, both of which appear to reflect the central vestibular signal-to-noise ratio, but not with VOR slow-phase accuracy, which is based on the magnitude of the central vestibular signals. Dizziness was related to the presence of a static central tone imbalance but not to any VOR metrics, suggesting that abnormal perception in VS may be affected by factors that are not captured by yaw-axis VOR measurements.NEW & NOTEWORTHY The severity of symptoms associated with unilateral vestibular schwannomas (VS) is poorly correlated with standard yaw-axis vestibulo-ocular reflex (VOR) metrics that are based on response amplitude. In this study, we show that the balance and perceptual dysfunction experienced by patients with VS scales with VOR metrics that capture information about the central signal-to-noise ratio (balance) and central static tone (dizziness), but are not correlated with the VOR gain, which reflects central signal amplitude.

Relationship between physical activity and dizziness handicap inventory in patients with dizziness -A multivariate analysis.

OBJECTIVE: A few studies have analyzed the physical activity in patients with dizziness. Levels of physical activity using 3-axial accelerometer were reported to be lower in patients with chronic dizziness compared to healthy adults. However, the sample size was small and confounding factors were not adjusted in the study. As the age, balance, anxiety, and depression likely contribute to dizziness, the contribution of physical activity to dizziness should be evaluated after adjusting for these potential confounders. We investigated the relationship between physical activity, postural stability, anxiety, and handicap in patients with dizziness using multivariate analysis. METHODS: This cross-sectional study included 59 patients with dizziness. The physical activity was measured using a 3-axial accelerometer. We also assessed the Dizziness Handicap Inventory (DHI), Hospital and Anxiety and Depression Scale (HADS), and the total center of pressure path length eyes open and eyes closed (COP_EO, COP_EC). To be eligible for analysis, the participants were required to wear the accelerometer for at least four days, with at least 10 h/day of wear time each day. RESULTS: There were significant differences in the light physical activity (LPA) and moderate to vigorous intensity physical activity (MVPA) between the mild (DHI ≦30) and severe (DHI > 60) groups. Factors that significantly affected the DHI_T score, in order of greater ß, were LPA, COP_EC, female, and HADS_A (ß = -0.546, 0.459, 0.437, 0.239, respectively). CONCLUSIONS: The present study demonstrated that the patients in the severe group had shorter LPA and MVPA times than that of the patients in the mild group. Additionally, LPA was associated with DHI_T in patients with dizziness. Therefore, physical activity, especially LPA (e.g., activities of daily living), may need to be assessed in patients with dizziness.

Uso da posturografia para identificação do risco de queda em idosos com tontura / Use of posturography to identify the risk of falling in elderly people with dizziness

RESUMO Objetivo avaliar se a posturografia, exame que avalia a habilidade de manter o equilíbrio em condições sensoriais conflitantes, pode identificar risco de queda em idosos com tontura. Métodos comparar os resultados posturográficos de idosos com e sem história de quedas, pareados por gênero, idade e diagnóstico etiológico da tontura. Resultados dezoito idosos com quedas - 4 com único episódio e 14 com história de 2 ou mais quedas no último ano - foram comparados com 18 idosos sem quedas, pareados por gênero, idade e diagnóstico etiológico. Pacientes com quedas apresentaram resultados piores para as análises de dependência visual (p=0,04, p=0,01, p=0,03). Pacientes com quedas recorrentes (2 ou mais episódios) apresentaram piores resultados em diversas condições sensoriais: somatossensorial, vestibular, dependências visuais e índice de equilíbrio composto. Conclusão a posturografia mostrou-se útil na identificação de idosos com quedas, principalmente em indivíduos com quadros recorrentes.

ABSTRACT Purpose the aim of this study is to determine whether posturography, an exam used to investigate the ability to maintain balance under conflicting sensory conditions, can identify the risk of falls in eldery patients with dizziness. Methods to compare the posturographic results of elderly people with falls vs elderly people with no falls, paired by sex, age and dizziness etiology. Results 18 fallers, and, of these, 14 with two or more falls in the last year were compared with 18 elderly people without falls. Comparing subjects without falls vs subjects with at least one fall in the last year, fallers obtain worse scores in conditions of visual dependence. Comparing non fallers with subjects with two or more falls, people with recurrent falls obtain worse score in several conditions: somatosensorial, vestibular, visual conflict, and in the main measure, the composite score. Conclusion posturography appears to be a useful tool to identify those at high risk of recurrent falls.

Dizziness in Parkinson's disease patients is associated with vestibular function.

Dizziness is common in Parkinson's disease (PD) patients. It is known that orthostatic hypotension (OH) is the main cause of such dizziness, but even without OH, quite a few PD patients complain of dizziness in the clinic. It can be regarded as non-specific because most of these patients have no neurological abnormalities. We hypothesized that this type of dizziness would be associated with vestibular function, although included patients did not have clinically confirmed vestibulopathy. We studied 84 patients without OH among 121 PD patients. Their clinical features and function were compared between patients with and without dizziness. Hoehn and Yahr stage (H&Y stage), the Unified Parkinson's Disease Rating Scale (UPDRS) part III, the Korean version of the Mini-Mental State Examination (K-MMSE), education years, disease duration, total levodopa equivalent daily dose (LEDD), the presence of dizziness, the dizziness severity, and orthostatic hypotension were tested. Vestibular evoked myogenic potentials (VEMPs) were used to characterize vestibular function. Ocular (oVEMPs) and cervical (cVEMPs) were recorded. oVEMPs in the right side showed significantly reduced potentials (p = 0.016) in PD patients with dizziness, but cVEMPs did not (all ps > 0.2). Bilateral absent oVEMP responses were more common in PD patients with dizziness (p = 0.022), but the frequencies of bilateral absent cVEMP responses were not different between the dizzy and non-dizzy groups (p = 0.898). Dizziness in PD patients without orthostatic hypotension may be associated with vestibular hypofunction. Our results provide evidence that can aid clinicians when making a treatment plan for patients with dizziness. i.e., strategies to enhance reduced vestibular function may be helpful, but this suggestion remains to be evaluated.

Effect of ingesting a meal and orthostasis on the regulation of splanchnic and systemic hemodynamics and the responsiveness of cardiovascular α1-adrenoceptors.

Postprandial orthostasis activates mechanisms of cardiovascular homeostasis to maintain normal blood pressure (BP) and adequate blood flow to vital organs. The underlying mechanisms of cardiovascular homeostasis in postprandial orthostasis still require elucidation. Fourteen healthy volunteers were recruited to investigate the effect of an orthostatic challenge (60°-head-up-tilt for 20 min) on splanchnic and systemic hemodynamics before and after ingesting an 800-kcal composite meal. The splanchnic circulation was assessed by ultrasonography of the superior mesenteric and hepatic arteries and portal vein. Systemic hemodynamics were assessed noninvasively by continuous monitoring of BP, heart rate (HR), cardiac output (CO), and the pressor response to an intravenous infusion on increasing doses of phenylephrine, an α1-adrenoceptor agonist. Neurohumoral regulation was assessed by spectral analysis of HR and BP, plasma catecholamine and aldosterone levels and plasma renin activity. Postprandial mesenteric hyperemia was associated with an increase in CO, a decrease in SVR and cardiac vagal tone, and reduction in baroreflex sensitivity with no change in sympathetic tone. Arterial α1-adrenoceptor responsiveness was preserved and reduced in hepatic sinusoids. Postprandial orthostasis was associated with a shift of 500 mL of blood from mesenteric to systemic circulation with preserved sympathetic-mediated vasoconstriction. Meal ingestion provokes cardiovascular hyperdynamism, cardiac vagolysis, and resetting of the baroreflex without activation of the sympathetic nervous system. Meal ingestion also alters α1-adrenoceptor responsiveness in the hepatic sinusoids and participates in the redistribution of blood volume from the mesenteric to the systemic circulation to maintain a normal BP during orthostasis.NEW & NOTEWORTHY A unique integrated investigation on the effect of meal on neurohumoral mechanisms and blood flow redistribution of the mesenteric circulation during orthostasis was investigated. Food ingestion results in cardiovascular hyperdynamism, reduction in cardiac vagal tone, and baroreflex sensitivity and causes a decrease in α1-adrenoceptor responsiveness only in the venous intrahepatic sinusoids. About 500-mL blood shifts from the mesenteric to the systemic circulation during orthostasis. Accordingly, the orthostatic homeostatic mechanisms are better understood.

Small vessel disease disrupts EEG postural brain networks in 'unexplained dizziness in the elderly'.

OBJECTIVE: To examine the hypothesis that small vessel disease disrupts postural networks in older adults with unexplained dizziness in the elderly (UDE). METHODS: Simultaneous electroencephalography and postural sway measurements were undertaken in upright, eyes closed standing, and sitting postures (as baseline) in 19 younger adults, 33 older controls and 36 older patients with UDE. Older adults underwent magnetic resonance imaging to determine whole brain white matter hyperintensity volumes, a measure of small vessel disease. Linear regression was used to estimate the effect of instability on electroencephalographic power and connectivity. RESULTS: Ageing increased theta and alpha desynchronisation on standing. In older controls, delta and gamma power increased, and theta and alpha power reduced with instability. Dizzy older patients had higher white matter hyperintensity volumes and more theta desynchronisation during periods of instability. White matter hyperintensity volume and delta power during periods of instability were correlated, positively in controls but negatively in dizzy older patients. Delta power correlated with subjective dizziness and instability. CONCLUSIONS: Neural resource demands of postural control increase with age, particularly in patients with UDE, driven by small vessel disease. SIGNIFICANCE: EEG correlates of postural control saturate in older adults with UDE, offering a neuro-physiological basis to this common syndrome.

Visual snow syndrome, the spectrum of perceptual disorders, and migraine as a common risk factor: A narrative review.

OBJECTIVE: The aim of this narrative review is to explore the relationship between visual snow syndrome (VSS), migraine, and a group of other perceptual disorders. BACKGROUND: VSS is characterized by visual snow and additional visual and nonvisual disturbances. The clinical picture suggests a hypersensitivity to internal and external stimuli. Imaging and electrophysiological findings indicate a hyperexcitability of the primary and secondary visual areas of the brain possibly due to an impairment of inhibitory feedback mechanisms. Migraine is the most frequent comorbidity. Epidemiological and clinical studies indicate that other perceptual disorders, such as tinnitus, fibromyalgia, and dizziness, are associated with VSS. Clinical overlaps and parallels in pathophysiology might exist in relation to migraine. METHODS: We performed a PubMed and Google Scholar search with the following terms: visual snow syndrome, entoptic phenomenon, fibromyalgia, tinnitus, migraine, dizziness, persistent postural-perceptual dizziness (PPPD), comorbidities, symptoms, pathophysiology, thalamus, thalamocortical dysrhythmia, and salience network. RESULTS: VSS, fibromyalgia, tinnitus, and PPPD share evidence of a central disturbance in the processing of different stimuli (visual, somatosensory/pain, acoustic, and vestibular) that might lead to hypersensitivity. Imaging and electrophysiological findings hint toward network disorders involving the sensory networks and other large-scale networks involved in the management of attention and emotional processing. There are clinical and epidemiological overlaps between these disorders. Similarly, migraine exhibits a multisensory hypersensitivity even in the interictal state with fluctuation during the migraine cycle. All the described perceptual disorders are associated with migraine suggesting that having migraine, that is, a disorder of sensory processing, is a common link. CONCLUSION: VSS, PPPD, fibromyalgia, and chronic tinnitus might lie on a spectrum of perceptual disorders with similar pathophysiological mechanisms and the common risk factor migraine. Understanding the underlying network disturbances might give insights into how to improve these currently very difficult to treat conditions.

Dizzy triathlete-evidence supporting vestibular etiology.

Dizziness during or after the swimming leg is a common complaint among triathletes. We hypothesized that the dizziness is caused by asymmetrical cooling of the vestibular organ. This caloric response is characterized by involuntary eye movements called nystagmus. Altogether, 125 triathletes completed an electronic questionnaire. Fifteen triathletes who had frequently experienced dizziness during the swimming leg agreed to take part in a cold water swimming test. The test comprised two cold water swimming legs, first without earplugs and then with earplugs to prevent a potential caloric response. Eye movements and possible nystagmus were recorded immediately after the swimming legs. A majority (87%, 109/125) of athletes had experienced dizziness during triathlon races or training. Of these, almost all (97%, 106/109) experienced it during or after swimming. Dizziness affected the triathlon performance in half of the athletes with dizziness (50%, 51/102). Fifteen athletes participated in a cold water swimming test. During the first leg (without earplugs), 11/15 athletes (73%) experienced dizziness. Of these, six had nystagmus (55%), four had uncertain nystagmus (36%), and one did not have nystagmus (9%). Only one of these athletes experienced dizziness during the second leg with earplugs. The prevalence of dizziness among triathletes is notable. A large part of the dizziness is likely to be caused by caloric reaction of the vestibular organ. We recommend earplug usage for triathletes suffering from dizziness during the swimming leg.

Impact of high-salt versus low-salt intake on the response of sympathetic baroreflex sensitivity to orthostasis in women with a history of normal pregnancy.

Previous studies have demonstrated that sympathetic baroreflex sensitivity (BRS) increases during orthostatic stress in humans. We recently showed that dietary salt intake affects sympathetic neural control in healthy premenopausal women. This study aimed to determine whether salt loading versus salt reduction would impact sympathetic BRS during orthostasis in premenopausal women with a history of normal pregnancy. Nine healthy women [42 ± 3 (SD) yr] were given a standardized isocaloric high-salt (250 mEq sodium/day) or low-salt (50 mEq sodium/day) diet for 1 wk each (∼2 mo apart with the order randomized), whereas water intake was ad libitum. Laboratory testing was performed following each high- and low-salt period in the midluteal phase of the menstrual cycle. Hemodynamics and muscle sympathetic nerve activity (MSNA) were measured at baseline (supine; 2 min) and during a graded head-up tilt (30° for 5 min and 60° for 20 min). Sympathetic BRS was assessed during baseline and head-up tilt. Hemodynamics were not different between salt conditions during baseline or tilt. Both supine and upright MSNA indices were lower in high salt than low salt (all P < 0.05), however, there was no interaction effect (P = 0.507-0.996). On moving from supine to upright, sympathetic BRS remained unchanged in high salt but increased in low salt (P = 0.028 for interaction). Thus, salt loading diminishes the responsiveness of sympathetic BRS during orthostasis compared with salt reduction in healthy premenopausal women with prior normal pregnancy. Whether this is one underlying mechanism for salt-induced development of hypertension during ambulation remains to be determined.