Autonomic nervous system disturbance as etiological background of vertigo and dizziness

Historical Therapies for Suspected Autonomic Dysregulation in Meniere's Disease

OBJECTIVE

This narrative review examines how speculative belief that the autonomic nervous system causes Meniere's Disease (MD) led otolaryngologists to adopt invasive surgical procedures and medical treatments still offered today.

DATA SOURCES

Google Scholar, PubMed.

REVIEW METHODS

A comprehensive literature review (1860-2022) was performed using the terms "Meniere AND (sympathetic OR sympathectomy OR vasomotor OR cervical ganglion)," returning 5360 items. All abstracts were briefly reviewed, relevant publications selected for further study, and key articles discussed by all authors. As it became clear that betahistine was related to the historical narrative, an additional search was performed using "Betahistine AND Meniere AND (vasomotor OR sympathetic OR sympathectomy OR cervical ganglion OR autonomic)," which yielded 336 results.

RESULTS

In the 19th and 20th centuries, growing knowledge of human anatomy led the scientific community to speculate that autonomic dysregulation caused many medical conditions. Excessive sympathetic mediated vasomotor changes were thought to cause hypertension, ischemia, and tissue damage. Clinicians applied the hypothesis to MD, assigning the sympathetic nervous system responsible for vertigo secondary to paroxysmal vasospasm and for hearing loss to poor cochlear nutrition. Despite limited animal experiments and isolated clinical observations, otolaryngologists performed sympathectomies, and, in the 1970s, replaced the procedure with betahistine as an alternative medical treatment.

CONCLUSION

Premature excitement about a plausible hypothesis led to unnecessary and unwarranted operations. Despite absent evidence of sympathetic overactivation in MD, surgeons eagerly adopted sympathectomies, and later betahistine. Rigorous evaluation of the validity of these treatment practices is needed.

LEVEL OF EVIDENCE

5 Laryngoscope, 134:535-542, 2024.

Effects of AHCC® on Immune and Stress Responses in Healthy Individuals

AHCC® is a functional food from the basidiomycete Lentinula edodes. We evaluated the effects of AHCC® on subjects under different kinds of stress and at rest. Physical stress was imposed using an active standing test, known as Schellong’s test. Sympathetic nervous activity in the standing position was significantly greater in AHCC®-treated subjects than in a placebo group. In contrast, AHCC® significantly increased parasympathetic nervous activity at rest. Under mental stress, AHCC® increased sympathetic nervous activity, with no difference in the parasympathetic nervous system. In subjects with chronic mental stress, self-reported “initiation and maintenance of sleep” was significantly greater in the AHCC®-intake period than in the placebo intake period, and natural killer cell activity also increased after AHCC® intake, suggesting a possible mechanism of action of AHCC®. Our findings indicate that AHCC® is potentially effective in stress management and may be useful in the treatment of depression.

Automatic classifier based on heart rate variability to identify fallers among hypertensive subjects

Accidental falls are a major problem of later life. Different technologies to predict falls have been investigated, but with limited success, mainly because of low specificity due to a high false positive rate. This Letter presents an automatic classifier based on heart rate variability (HRV) analysis with the goal to identify fallers automatically. HRV was used in this study as it is considered a good estimator of autonomic nervous system (ANS) states, which are responsible, among other things, for human balance control. Nominal 24 h electrocardiogram recordings from 168 cardiac patients (age 72 ± 8 years, 60 female), of which 47 were fallers, were investigated. Linear and nonlinear HRV properties were analysed in 30 min excerpts. Different data mining approaches were adopted and their performances were compared with a subject-based receiver operating characteristic analysis. The best performance was achieved by a hybrid algorithm, RUSBoost, integrated with feature selection method based on principal component analysis, which achieved satisfactory specificity and accuracy (80 and 72%, respectively), but low sensitivity (51%). These results suggested that ANS states causing falls could be reliably detected, but also that not all the falls were due to ANS states.

The comparative usefulness of orthostatic testing and tilt table testing in the evaluation of autonomic-associated dizziness

OBJECTIVE

To elucidate the usefulness of clinical orthostatic blood pressure testing (COBP) as a screening tool for autonomic dysfunction.

STUDY DESIGN

In this retrospective case review, the records of 156 consecutive patients with nonotologic dizziness as the primary complaint seen in an academic neurotology clinic between 2005 and 2009 were reviewed. The objective of this study was accomplished by comparing the diagnostic yield of COBP with that of head-upright tilt table testing (HUT) and assessing the sensitivity and specificity of COBP in predicting an abnormal HUT in patients with nonotologic dizziness.

SETTING

Ambulatory tertiary referral center.

PATIENTS

Patients presenting to the clinic with dizziness without otologic cause.

INTERVENTION(S)

Clinical evaluation, orthostatic blood pressure testing, and HUT.

MAIN OUTCOME MEASURE(S)

The primary outcome assessed in this study was patient blood pressure. Blood pressures were measured in the clinic in the following order: supine, sitting, and standing. Positive COBP was defined as a reduction in systolic or diastolic blood pressure greater than 20 or 10 mm Hg, respectively, or both, within 3 minutes of sitting from supine or standing from sitting. For comparison, HUT was used as the gold standard. A positive HUT was defined as a reduction in systolic or diastolic blood pressure greater than 20 or 10 mm Hg, respectively, or both, relative to baseline at any point after initiation of HUT.

RESULTS

Forty patients were referred for HUT. Twenty-four (61.5%) of these patients were deemed to have a positive response. Thirty-three patients (85%) referred to HUT were initially evaluated with COBP, which revealed orthostatic hypotension (OH) in 8 patients (24%). COBP was calculated to have sensitivity and specificity of 21% and 71%, respectively, when asymptomatic OH was included in the positivity criteria. When asymptomatic OH was excluded from the positivity criteria, the sensitivity and specificity remained similar at 25% and 76%, respectively. However, the exclusion of asymptomatic OH from the positivity criteria resulted in a decrease in the positive predictive value from 50% to 25% and an increase in the negative predictive value from 40% to 76%. Overall, HUT detected 16 patients with an abnormal result that were missed by COBP testing.

CONCLUSION

Evaluation for autonomic dysfunction should be part of the comprehensive evaluation of a dizzy patient, involving, at a minimum, orthostatic testing of blood pressure and heart rate. Patients with nonotologic dizziness and light-headedness with a normal neurotologic evaluation can reasonably be referred for HUT, even in the presence of normal in-office orthostatic testing.

Autonomic related vertigo

OBJECTIVES

To demonstrate clinical evidence that vestibular symptomatology can occur in relation to autonomic dysfunction. Characterization of clinical findings and treatment response would then allow autonomic related vertigo to be differentiated from other vertiginous conditions that present in a like manner.

STUDY DESIGN

This was a retrospective review of 113 patients that described symptoms consistent with spontaneous, rotational vertigo and autonomic dysfunction.

METHODS

Vestibular, otologic, and autonomic symptoms are presented along with the results of audiologic, orthostatic, and autonomic testing. Medical management included fluid loading, dietary changes, exercise, and patient education. Treatment results were analyzed according to the effectiveness in control of vestibular and otologic symptoms. Results were compared with a control group that demonstrated a similar vestibular and otologic presentation without autonomic symptomatology.

RESULTS

All patients described spontaneous, rotational vertigo, with complete or substantial vertigo control obtained in 93 (85%) of 110 patients. Postural vertigo and distinct lightheadedness were also documented in 53% and 97% of cases, respectively. Vertigo failed to improve or worsened with prior treatment of low sodium diet or diuretic in 53 (91%) of 58 cases. Vertigo improvement was subsequently achieved in 48 (86%) of 56 cases with an autonomic treatment regimen. Long-term vertigo control was obtained in 56 (88%) of 64 patients followed for at least 18 months. Tinnitus was reported in 97 (86%) patients, aural fullness in 93 (82%) patients, and subjective hearing loss (HL) in 46 (41%) of 111 cases. Bilateral tinnitus and aural fullness occurred in 65% and 63%, respectively. Tinnitus improved with treatment in 56 (67%) of 84 patients, whereas aural fullness improved in 59 (74%) of 80 patients. Autonomic symptoms included palpitations in 103 (91%) patients, chronic fatigue in 102 (90%) patients, cold extremities in 91 (81%) patients, and previous fainting in 72 (64%) patients. A history of mitral valve prolapse was documented in 51 (45%) of cases and demonstrated with echocardiogram in 68 (93%) of the 73 patients tested. Audiologic testing was normal in 104 (95%) of 109 patients, and electrocochleography was abnormal in 42 (40%) of 105 patients. Orthostatic blood pressure and heart rate testing met the criteria for orthostatic hypotension in 16 (15%) of 104 patients. Autonomic testing was obtained in 34 cases, with orthostatic intolerance demonstrated in 33 (97%) patients and orthostatic hypotension demonstrated in 13 (38%) patients. Overall, orthostatic hypotension was documented through combined testing results in 23 (21%) of 107 patients. Vertigo was reproduced during autonomic testing in 17 (77%) of 22 patients, and otologic symptoms were reproduce in 9 (47%) of 19 patients. Comparison of the study population with a control group without autonomic symptoms revealed statistically significant differences in orthostatic testing and treatment results. There was no statistical difference noted in findings between patients of this study that demonstrated or failed to demonstrate orthostatic hypotension.

CONCLUSIONS

There is a subgroup of patients with spontaneous vertigo who also demonstrate symptoms and findings consistent with poor autonomic regulation. These patients report vertigo improvement with a treatment strategy that aims to improve autonomic dysfunction through expansion of effective circulating volume. Clinical findings and treatment results of this study suggest an underlying autonomic influence in the production of vertigo and otologic symptoms.

Musculoskeletal diseases as a causal factor of cervical vertigo

OBJECTIVE

To analyze the frequency of musculoskeletal diseases in patients with cervical vertigo, as well as the relations of neck tenderness, psychiatric symptoms, and autonomic abnormalities with pain and age.

METHODS

One hundred and seventy-six patients with cervical vertigo were analyzed. The groups with or without pain and the groups aged > or =66 years or < or =65 years old were compared.

RESULTS

Musculoskeletal diseases were very common (present in 86%). In the group with pain, neck tenderness, CMI III-IV, and orthostatic hypotension were significantly more frequent. In the older group, neck tenderness and orthostatic hypotension were significantly more common than in the younger group. Abnormal ETT and OKP results were also frequently observed.

CONCLUSIONS

Musculoskeletal diseases might have a role in cervical vertigo. In addition, there seem to be some relations among neck tenderness, psychiatric symptoms, autonomic abnormalities, pain, and age. Furthermore, brain stem abnormalities may participate in cervical vertigo.

Autonomic Nervous System Function in Chronic Dizziness

OBJECTIVE

The goals of this study were to validate the clinical diagnosis of autonomic dizziness as a cause of chronic nonvertiginous dizziness that may be exacerbated by physical exertion or orthostatic challenges, estimate its prevalence in a tertiary referral population, and investigate the usefulness of three autonomic challenges as objective tests for this condition.

STUDY DESIGN

Laboratory investigation of autonomic activity.

SETTING

Tertiary care balance center.

PATIENTS

Fifteen men and women with symptoms indicative of autonomic dizziness. Subjects with other causes of dizziness, histories of syncope, or psychiatric disorders were excluded.

INTERVENTIONS

Autonomic tests included 45 minutes of head upright tilt (HUT), 20 minutes of 5% CO2 inhalation and then HUT, and 2 minutes of voluntary hyperventilation and then HUT.

MAIN OUTCOME MEASURES

Patterns of cardiovascular and respiratory responses and subjective ratings of dizziness, autonomic symptoms, and anxiety during autonomic challenges.

RESULTS

Twelve subjects had evidence of autonomic dysfunction, including 10 with abnormal heart rate, blood pressure, or respiratory responses to HUT. Two other subjects had prolonged hypocarbia after voluntary hyperventilation. Many of these abnormalities would have been missed by current autonomic testing paradigms. In one subject, CO2 inhalation revealed latent anxiety. In two subjects, the presence of high symptom ratings without objective autonomic dysfunction prompted a successful search for other diagnoses.

CONCLUSION

Study results validated the clinical syndrome of autonomic dizziness. Autonomic testing protocols may have to be updated to detect clinically relevant abnormalities in patients with dizziness.

Caloric test and simultaneous recording of sympathetic skin response

CONCLUSIONS

It was found that there was a close correlation between sympathetic skin response (SSR) parameters and nystagmus parameters obtained in caloric tests. Further studies are needed to investigate the clinical correlation of these findings.

OBJECTIVES

To investigate whether the caloric response creates a measurable SSR and, if so, to compare the SSR parameters with the nystagmus parameters and the feelings of the patient.

MATERIAL AND METHODS

Patients completed an autonomic symptom questionnaire (ASQ) regarding their past history of autonomic symptoms. They used a visual analog scale (VAS) to assess the severity of symptoms during simultaneous SSR and caloric tests. Symptoms were also noted separately by the investigator.

RESULTS

Eighteen patients were included in the study (13 females, 5 males). Eight of the patients had central and 10 had peripheral vertigo. The mean VAS score was 6.6+/-1.9 and the mean ASQ score was 7.2+/-3.6. In terms of the recorded parameters, there were no significant differences between patients with central and peripheral vertigo, males and females or warm and cold irrigation. The number of SSR waves increased significantly when the slow-phase velocity was > 26 degrees/s (p<0.01) and the nystagmus latency was < or = 27 s (p<0.05). The VAS score was also correlated with the number of SSR waves (p<0.01).

Multiple system atrophy manifested as dizziness and imbalance: a report of two cases

Multiple system atrophy (MSA) is a progressive neurodegenerative disease of undetermined origin that occasionally manifests as dizziness and imbalance. It is not often considered in clinical situations, especially not by neuro-otological consultants. Hence, we report our recent experience with two cases of MSA. One is that of a 62-year-old man with MSA with a predominant cerebellar feature, and the other is that of a 72-year-old man with MSA with a predominant parkinsonian feature. The results of the syncopic study correlated with orthostatic hypotension. The neuro-otological study in both patients revealed an abnormal eye tracking test, abnormal optokinetic nystagmus test and loss of visual suppression in the caloric nystagmus. These indicate that the central vestibular system, e.g., the cerebellum or brain stem, is affected by MSA, contributing to dizziness and imbalance. Therefore, diagnosis of MSA should be kept in mind by neuro-otological consultants when dealing with patients with dizziness and imbalance, especially when this is accompanied by orthostatic hypotension.

Exertional dizziness and autonomic dysregulation

OBJECTIVES

To define the clinical characteristics and treatment of dizziness induced by physical exertion and to investigate autonomic nervous system function in exertional dizziness.

STUDY DESIGN

Retrospective case series from a review of 1400 patients evaluated for dizziness at a neurotology referral center, identifying those with predominantly exertional symptoms.

METHODS

Records of patients with exertional dizziness were screened to eliminate those with known vestibular deficits, cardiopulmonary illnesses, and psychiatric disorders. The clinical characteristics, evaluation results, and treatment of nine patients with purely exertional dizziness were described.

RESULTS

The cohort included 4 male and 5 female patients (age range, 13-53 y) with symptoms for 1 to 8 years. Only one patient had a history of autonomic symptoms: phlebotomy-induced syncope in childhood. No patient was taking medications that caused dizziness or orthostasis. All patients experienced "spacey" or "foggy" head sensations without vertigo during exertion. Provocative activities ranged from standing upright for extended periods to running and swimming. On examination, voluntary hyperventilation provoked moderate symptoms in all patients (without nystagmus or anxiety), although no patient had spontaneously occurring, hyperventilation-related complaints. Seven patients underwent autonomic testing. Tilt table tests (n = 5) produced severe symptoms in one patient and mild symptoms in two patients. Sodium lactate infusions (n = 6) provoked marked symptoms in four patients and moderate symptoms in one patient. All were treated for autonomic dysregulation. Seven patients improved substantially and resumed all of their premorbid activities. Two improved slightly.

CONCLUSIONS

In nine patients with exertional dizziness, autonomic challenges were provocative, and medications for autonomic dysregulation were effective. Exertional dizziness may be a clinical manifestation of autonomic nervous system dysregulation.

The effects of systolic arterial blood pressure variations on postoperative nausea and vomiting

In this clinical study, we tested the hypothesis that a marked systolic blood pressure decrease >35% (DeltaSBP >35%) from preanesthetic baseline during the induction and maintenance of anesthesia is associated with more postoperative nausea and vomiting (PONV). In 300 ASA physical status I and II women undergoing elective gynecological surgery with general anesthesia, the maximum DeltaSBP during the induction as well as maintenance of general anesthesia were calculated. Observers blinded to hemodynamic variables assessed the incidence of PONV. The overall incidence of nausea (visual analog scale >4) and vomiting within the immediate observation period (0-2 h) was 39% and 25%, respectively. Frequency of nausea and vomiting in the late observation period was 21% and 9%, respectively. Women with a DeltaSBP >35% during the induction of anesthesia suffered from a more frequent incidence of PONV within the immediate (57% versus 35% and 41% versus 22%, respectively; P < 0.01) and within the late observation period (33% versus 18% and 19% versus 7%, respectively; P < or = 0.01). In women with a DeltaSBP >35% during maintenance of anesthesia, a more frequent incidence of nausea within the immediate observation period (53% versus 36%; P < 0.05) was found. We conclude that a maximum DeltaSBP >35% during the anesthetic induction is associated with an increased incidence of PONV after gynecological surgery during general anesthesia.

IMPLICATIONS

A prospective clinical investigation revealed that a marked systolic blood pressure decrease >35% (DeltaSBP >35%) during the induction of general anesthesia is associated with an increased incidence of postoperative nausea and vomiting (PONV). The association between a DeltaSBP >35% during maintenance of general anesthesia and PONV is less pronounced.

Comparative Effects of Sertraline and Nortriptyline on Body Sway in Older Depressed Patients

This study examined effects of nortriptyline and sertraline on the balance and stability of depressed geriatric inpatients. Body sway was measured with a stable force-platform at three timepoints: before starting antidepressant medication, 5-7 days after medication was initiated, and 1 week later. A group of healthy, unmedicated older volunteers was evaluated under the same conditions as patients. In sertraline-treated patients (n = 10), significant differences (P < 0.05) between baseline and the first week of treatment were found in the force-platform measurements of sway length (L) and area of the center of pressure (Ao), with patients' eyes both open and closed. This change in postural stability occurred in the absence of orthostatic hypotension. By the second week of treatment, neither variable was found to be significantly different from baseline. In the nonmedicated volunteers (n = 20) and in the group of patients receiving nortriptyline (n = 11), no significant changes in postural stability were found.