Significant Temporal Association of Esophageal Air Events (Supragastric Belches, Air Swallows, and Gastric Belches) With Hiccups: A Case Study in an Adolescent

We previously reported our ability to objectively assess the strength of temporal relationships between gastroesophageal reflux (GER) disease-like symptoms with esophageal air events (EAEs) (air swallows, gastric belching, and supragastric belching) using impedance-pH monitoring. Recently, we similarly evaluated an adolescent female who presented to our clinic with symptoms of recurrent hiccups and with what appeared to be numerous EAEs. Hiccups were associated with GER (symptom association probability [SAP] = 100%), air swallows (SAP = 99.7%), supragastric belches (SAP = 100%), and gastric belches (SAP = 100%), with almost twice as many of the supragastric belches preceding a hiccup than any of the other 3 esophageal disturbance types (EDs) (P < 0.00001). Our data showing a significant temporal association between EAEs and hiccups support a previous report in which belching was suspected of being associated with hiccups in an adult male. Reports such as this underscore the importance of considering the assessment of temporal relationships between extra-esophageal symptoms and EDs that include not only GER, but also EAEs, such as air swallows, gastric belches and supragastric belches, when devising strategies for clinical management of patients with hiccups.

Trigeminocardiac Reflex as a Complication of Excision of Schwannoma of the Trigeminal Nerve - A Rare Clinical Case Report

Rationale

Trigeminal schwannoma (TS) is a very rare tumour in the head-and-neck region and the occurrence of intraoperative trigeminocardiac reflex (TCR), during surgery, should not be underestimated. The physiological function of this rare brainstem reflex is yet to be fully established.

Patient Concerns

TCR occurs in a variety of surgeries, such as neurosurgical, maxillofacial, dental and skull base surgeries with bradycardia as the presenting sign.

Diagnosis

This is a clinical profile of two patients who presented with schwannoma of the trigeminal nerve.

Outcomes

Intraoperatively, during dissection of tumour, both patients had bradycardia with hypotension.

Treatment

The first patient had a spontaneous recovery but the other required intervention with vasopressors.

Take-Away Lessons

One must be aware of the rare occurrence of TCR mainly while operating on a rare occurring TS. Ceaseless intraoperative monitoring and being prepared with adequate measures while manipulating close to the nerve will prevent serious complications.

Deglutition Syncope Due to Exaggerated Vagal Reflex

Swallow or deglutition syncope is an uncommon cause of syncope associated with bradyarrhythmia and hypotension during food swallowing. Early recognition of this condition is imperative but challenging. We report a case of a 60-year-old female who presented with a complaint of intermittent lightheadedness after swallowing food. An episode of presyncope was observed and a reduced pulse rate from baseline was noted when she was instructed to eat a candy bar in the clinic. Further workup revealed normal in-office electrocardiogram, bilateral carotid ultrasound, transthoracic echocardiogram, and videofluoroscopic swallow study. Our goal in presenting this case is to raise awareness of the condition in medical literature and provide a good understanding of its clinical manifestation to prevent life-threatening events.

Complete atrioventricular dissociation and sinus arrest after pheochromocytoma resection

INTRODUCTION

Although preoperative bradycardia has been reported in several pheochromocytoma cases, postoperative bradycardia has not. This is the first case report of complete atrioventricular dissociation and sinus arrest occurring after pheochromocytoma resection.

CASE PRESENTATION

A 38-year-old woman was referred for a left adrenal incidentaloma. Twenty-four hour urinary collection showed elevated noradrenaline. Iodine-123-meta-iodobenzylguanidine scintigraphy showed high tracer uptake in the left adrenal region. Open left adrenalectomy was performed, and histopathological examination confirmed the diagnosis of pheochromocytoma. Thirty minutes following surgery, complete atrioventricular dissociation and sinus arrest developed. Vagal reflex attenuation due to decreased noradrenaline after tumor removal and perioperative pain and fear were believed to be the causes. A temporary pacemaker was implanted to prevent sudden death due to vagal overstimulation.

CONCLUSION

Vagal reflex attenuation after pheochromocytoma resection can result in complete atrioventricular dissociation and sinus arrest. Adequate preoperative preparation and close monitoring during and after surgery are imperative.

Vagal Regulation of Group 3 Innate Lymphoid Cells and the Immunoresolvent PCTR1 Controls Infection Resolution

Uncovering mechanisms that control immune responses in the resolution of bacterial infections is critical for the development of new therapeutic strategies that resolve infectious inflammation without unwanted side effects. We found that disruption of the vagal system in mice delayed resolution of Escherichia coli infection. Dissection of the right vagus decreased peritoneal group 3 innate lymphoid cell (ILC3) numbers and altered peritoneal macrophage responses. Vagotomy resulted in an inflammatory peritoneal lipid mediator profile characterized by reduced concentrations of pro-resolving mediators, including the protective immunoresolvent PCTR1, along with elevated inflammation-initiating eicosanoids. We found that acetylcholine upregulated the PCTR biosynthetic pathway in ILC3s. Administration of PCTR1 or ILC3s to vagotomized mice restored tissue resolution tone and host responses to E. coli infections. Together these findings elucidate a host protective mechanism mediated by ILC3-derived pro-resolving circuit, including PCTR1, that is controlled by local neuronal output to regulate tissue resolution tone and myeloid cell responses.

Do small doses of atropine (<0.1 mg) cause bradycardia in young children?

OBJECTIVE

To determine the heart rate response to atropine (<0.1 mg) in anaesthetised young infants.

DESIGN

Prospective, observational and controlled.

SETTING

Elective surgery.

PATIENTS

Sixty unpremedicated healthy infants less than 15 kg were enrolled. Standard monitoring was applied. Anaesthesia was induced by mask with nitrous oxide (66%) and oxygen (33%) followed by sevoflurane (8%).

INTERVENTIONS

Intravenous (IV) atropine (5 µg/kg) was flushed into a fast flowing IV. The ECG was recorded continuously from 30 s before the atropine until 5 min afterwards.

MAIN OUTCOME MEASURES

The incidence of bradycardia and arrhythmias was determined from the ECGs by a blinded observer.

RESULTS

The median (IQR) age was 6.5 (4-12) months and the mean (95% CI) weight was 8.6 (8.1 to 9.1) kg. The mean (95% CI) dose of atropine was 40.9 (37.3 to 44) µg. Bradycardia did not occur. Two infants developed premature atrial contractions and one developed a premature ventricular contraction. When compared with baseline values, heart rate increased by 7% 30 s after atropine, 14% 1 min after atropine and 25% 5 min after atropine. Twenty-nine infants (48%) experienced tachycardia (>20% above baseline rate) after atropine lasting 222.7 s (range 27.9-286). The change in heart rate 5 min after atropine was inversely related to the baseline heart rate.

CONCLUSIONS

The upper 95% CI for the occurrence of bradycardia in the entire population of infants based on a zero incidence in this study is 5%. These results rebut the notion that atropine <0.1 mg IV causes bradycardia in young infants.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov #NCT01819064.

Nicotine enhances inhibition of mouse vagal motor neurons by modulating excitability of premotor GABAergic neurons in the nucleus tractus solitarii

The caudal nucleus of the solitary tract (NTS) serves as the site of the first synapse for visceral sensory inputs to the central nervous system. The NTS sends functional projections to multiple brain nuclei, with gastric-related projections primarily targeting the dorsal motor nucleus of the vagus (DMV). Previous studies have demonstrated that the majority of caudal NTS neurons that project to the DMV respond robustly to nicotine and express nicotinic acetylcholine receptors (nAChRs). However, the cytochemical identity and relationship with specific viscera of DMV-projecting, nicotine-responsive caudal NTS neurons have not been determined. The present study used transgenic mice that express enhanced green fluorescent protein (EGFP) under a GAD67 promoter in a subset of GABAergic neurons, in vivo retrograde pseudorabies viral labeling to identify gastric-related vagal complex neurons, and patch-clamp electrophysiology in acute brain stem slices to test the hypothesis that gastric-related and GABAergic inhibitory synaptic input to the DMV from the caudal NTS is under a robust modulatory control by nAChRs. Our results suggest that activation of nAChRs in the caudal NTS, but not DMV, potentiates GABAergic, but not glutamatergic, input to the DMV. Gastric-related caudal NTS and DMV neurons are directly involved in this nicotine-sensitive circuitry. Understanding the central patterns of nicotinic modulation of visceral sensory-motor circuitry may help develop therapeutic interventions to restore autonomic homeostasis in patients with autonomic impairments.

Progressive dysautonomia in two patients with xeroderma pigmentosum group A

BACKGROUND

Xeroderma pigmentosum group A (XPA) is a rare autosomal-recessive disorder caused by a defect in nucleotide excision repair. Progressive dysautonomia in patients with XPA is rarely described.

PATIENTS

Two juvenile male patients with XPA suffered from dysphagia, sleep interruption, and dysuria from the age of 10 to 19 years, successively. These autonomic symptoms might have been caused by progressive descending degeneration of cranial nerves IX and X and the sacral parasympathetic nerve, including Onuf's nucleus. One patient died from sudden cardiopulmonary arrest during postural change and tracheal suction.

RESULTS

Heart rate variability analyses of these patients revealed parasympathetic dysautonomia, based on decreased high-frequency values.

CONCLUSIONS

The insidiously progressive dysautonomia in these two patients with XPA suggested progressive descending degeneration extending from the medulla oblongata to the sacral spinal cord, which is an ominous sign of end-stage disease and a risk factor of sudden death attributable to XPA.

Modulation of gastrointestinal vagal neurocircuits by hyperglycemia

Glucose sensing within autonomic neurocircuits is critical for the effective integration and regulation of a variety of physiological homeostatic functions including the co-ordination of vagally-mediated reflexes regulating gastrointestinal (GI) functions. Glucose regulates GI functions via actions at multiple sites of action, from modulating the activity of enteric neurons, endocrine cells, and glucose transporters within the intestine, to regulating the activity and responsiveness of the peripheral terminals, cell bodies and central terminals of vagal sensory neurons, to modifying both the activity and synaptic responsiveness of central brainstem neurons. Unsurprisingly, significant impairment in GI functions occurs in pathophysiological states where glucose levels are dysregulated, such as diabetes. A substantial obstacle to the development of new therapies to modify the disease, rather than treat the symptoms, are the gaps in our understanding of the mechanisms by which glucose modulates GI functions, particularly vagally-mediated responses and a more complete understanding of disease-related plasticity within these neurocircuits may open new avenues and targets for research.

Does topical anesthesia using aerosolized lidocaine inhibit the superior laryngeal nerve reflex?

OBJECTIVE

This study was designed to evaluate the effectiveness of topical lidocaine in attenuating the laryngeal reflex and blunting hemodynamic response by inhibition of the superior laryngeal nerve in laryngeal microsurgery, which would be helpful in preventing potential complications.

STUDY DESIGN

A prospective, randomized, double-blind study.

SETTING

Tertiary medical center.

SUBJECTS AND METHODS

Fifty-four patients requiring glottic and supraglottic laryngeal microsurgery were randomly assigned to 1 of 2 groups, with equal numbers. Before surgery, 10% lidocaine was topically applied to the laryngeal surface of the epiglottis and vocal folds under direct vision in the study group and saline aerosol was applied in the control group. Heart rates, arterial blood pressure, and SPO2 were recorded at baseline, after induction, immediately before and after intubation, during the surgery, and upon extubation. Laryngospasm, agitation, and coughing were recorded during the recovery period.

RESULTS

Heart rates, arterial pressure, and SPO2 did not differ significantly from baseline to postintubation period among the groups. SPO2 values measured similar in the remaining study. Heart rates and blood pressures were slightly decreased in the study group after lidocaine administration, but only blood pressure at pre- and post-extubation was significantly decreased in the study group (P < .05). Also laryngospasm and coughing were not statistically different between the 2 groups. There was an obvious gap between the 2 groups for agitation. Study group agitation was noted significantly lower (P < .05).

CONCLUSION

These findings indicate that preoperative topical lidocaine application may be helpful in attenuating airway-circulatory reflexes in laryngeal microscopic surgery.

Selective inhibition of vagal afferent nerve pathways regulating cough using Nav 1.7 shRNA silencing in guinea pig nodose ganglia

Adeno-associated virus delivery systems and short hairpin RNA (shRNA) were used to selectively silence the voltage-gated sodium channel NaV 1.7 in the nodose ganglia of guinea pigs. The cough reflex in these animals was subsequently assessed. NaV 1.7 shRNA was delivered to the majority of nodose ganglia neurons [50-60% transfection rate determined by green fluorescent protein (GFP) gene cotransfection] and action potential conduction in the nodose vagal nerve fibers, as evaluated using an extracellular recording technique, was markedly and significantly reduced. By contrast, <5% of neurons in the jugular vagal ganglia neurons were transfected, and action potential conduction in the jugular vagal nerve fibers was unchanged. The control virus (with GFP expression) was without effect on action potential discharge and conduction in either ganglia. In vivo, NaV 1.7 silencing in the nodose ganglia nearly abolished cough evoked by mechanically probing the tracheal mucosa in anesthetized guinea pigs. Stimuli such as capsaicin and bradykinin that are known to stimulate both nodose and jugular C-fibers evoked coughing in conscious animals was unaffected by NaV 1.7 silencing in the nodose ganglia. Nodose C-fiber selective stimuli including adenosine, 2-methyl-5-HT, and ATP all failed to evoke coughing upon aerosol challenge. These results indicate that cough is independently regulated by two vagal afferent nerve subtypes in guinea pigs, with nodose Aδ fibers regulating cough evoked mechanically from the trachea and bradykinin- and capsaicin-evoked cough regulated by C-fibers arising from the jugular ganglia.

Phasic and long-term depression in brainstem nucleus tractus solitarius neurons: differing roles of AMPA receptor desensitization

One important question concerning the homeostatic regulation of many physiological processes is whether the control mechanisms are purely reflexogenic or whether they may involve neural adaptation in the form of learning and memory in the brainstem. Using a brainstem slice preparation in the rat, we studied the modifiability of neural transmission in the first-order synapses of the medial and commissural nucleus tractus solitarius of the medulla. Sustained low-frequency stimulation (5 Hz) of primary afferent fibers in the tractus solitarius resulted in a phasic depression (accommodation) of synaptic strength as reflected by a concomitant decrease in the evoked excitatory postsynaptic potentials. In one group of neurons (type I), synaptic strength recovered rapidly after low-frequency stimulation, whereas in another group of neurons (type II), synaptic strength remained depressed for >30 min, i.e., manifesting long-term depression (LTD). The latter was switched into a short-term depression lasting 15-25 min after pharmacological blockade of NMDA receptor channels with D-APV or chelation of intracellular calcium ions with EGTA, whereas the accommodation phase was unaffected. Application of an AMPA receptor anti-desensitization agent cyclothiazide abolished the LTD, but not the accommodation response. These results suggest the presence of separate postsynaptic sites for the induction of LTD and accommodation, one being sensitive to cyclothiazide, whereas the other is not. Moreover, the maintenance of LTD is dependent on the level of intracellular Ca2+. These phasic and long-term synaptic plasticity in the nucleus tractus solitarius may play a role in the homeostatic regulation of cardiorespiratory functions.