Vagal Nerve Palsy After Transarterial Embolization of Transverse-Sigmoid Dural Arteriovenous Fistula Using Onyx

OBJECTIVE

We report a case of a 70-year-old man who developed a transverse-sigmoid dural arteriovenous fistula (TS-DAVF) that was successfully treated by transarterial embolization (TAE) with Onyx.

CASE PRESENTATION

The patient presented with sudden and progressive disturbance of consciousness and left hemiparesis. Magnetic resonance imaging (MRI) revealed venous infarction and hemorrhagic changes with brain swelling in the right parietal lobe. Angiography revealed a right TS-DAVF and multiple occlusions with retrograde leptomeningeal venous drainage into the cortical veins. The TS-DAVF was graded as Borden type III and Cognard type IIa+b. Because of its progressive clinical nature and wide distribution of DAVF in the occluded sinus wall, he underwent emergent TAE with liquid embolic materials including n-butyl cyanoacrylate and Onyx under informed consent by his family. Complete obliteration of the TS-DAVF was achieved, leading to a marked amelioration of symptoms, and MRI after treatment confirmed a decrease in the brain swelling. However, he suffered transient dysphagia due to right vagal nerve palsy caused by occlusion of vasa nervorum of ascending pharyngeal artery. He returned home 5 months later with a modified Rankin Scale of 1.

CONCLUSIONS

TAE with Onyx appears to be effective for aggressive TS-DAVF with a widely distributed shunt. However, the blood supply to the cranial nerves and potentially dangerous anastomoses between the external-internal carotid artery and vertebral artery should be taken into account to avoid serious complications.

A 68-year-old with cranial nerve neuropathies and a troponin rise

In this case study, we summarise the inpatient investigations and management of a 68-year-old woman with Takotsubo cardiomyopathy secondary to a Varicella zoster encephalitis and the difficulties inherent with making this diagnosis. She presented with evolving cranial nerve neuropathies, which started with a vagal nerve mononeuritis and eventually included left-sided sensorineural hearing loss and a facial nerve palsy. These symptoms were concomitant with a variety of cardiac abnormalities, including fast atrial fibrillation and electrocardiographic changes. We summarise some of the current understanding of Takotsubo cardiomyopathy and the criteria for its diagnosis. Although left ventricular apical ballooning has been described in association with severe infections and states of high stress, we have not seen it reported in association with a Varicella zoster encephalitis.

Role of capsaicin-sensitive peripheral sensory neurons in anorexic responses to intravenous infusions of cholecystokinin, peptide YY-(3-36), and glucagon-like peptide-1 in rats

Cholecystokinin (CCK)-induced suppression of feeding is mediated by vagal sensory neurons that are destroyed by the neurotoxin capsaicin (CAP). Here we determined whether CAP-sensitive neurons mediate anorexic responses to intravenous infusions of gut hormones peptide YY-(3-36) [PYY-(3-36)] and glucagon-like peptide-1 (GLP-1). Rats received three intraperitoneal injections of CAP or vehicle (VEH) in 24 h. After recovery, non-food-deprived rats received at dark onset a 3-h intravenous infusion of CCK-8 (5, 17 pmol·kg⁻¹·min⁻¹), PYY-(3-36) (5, 17, 50 pmol·kg⁻¹·min⁻¹), or GLP-1 (17, 50 pmol·kg⁻¹·min⁻¹). CCK-8 was much less effective in reducing food intake in CAP vs. VEH rats. CCK-8 at 5 and 17 pmol·kg⁻¹·min⁻¹ reduced food intake during the 3-h infusion period by 39 and 71% in VEH rats and 7 and 18% in CAP rats. In contrast, PYY-(3-36) and GLP-1 were similarly effective in reducing food intake in VEH and CAP rats. PYY-(3-36) at 5, 17, and 50 pmol·kg⁻¹·min⁻¹ reduced food intake during the 3-h infusion period by 15, 33, and 70% in VEH rats and 13, 30, and 33% in CAP rats. GLP-1 at 17 and 50 pmol·kg⁻¹·min⁻¹ reduced food intake during the 3-h infusion period by 48 and 60% in VEH rats and 30 and 52% in CAP rats. These results suggest that anorexic responses to PYY-(3-36) and GLP-1 are not primarily mediated by the CAP-sensitive peripheral sensory neurons (presumably vagal) that mediate CCK-8-induced anorexia.

Cranial nerve vascular compression syndromes of the trigeminal, facial and vago-glossopharyngeal nerves: comparative anatomical study of the central myelin portion and transitional zone; correlations with incidences of corresponding hyperactive dysfunctional syndromes

OBJECTIVE

The aim of this study was to evaluate the anatomy of the central myelin portion and the central myelin-peripheral myelin transitional zone of the trigeminal, facial, glossopharyngeal and vagus nerves from fresh cadavers. The aim was also to investigate the relationship between the length and volume of the central myelin portion of these nerves with the incidences of the corresponding cranial dysfunctional syndromes caused by their compression to provide some more insights for a better understanding of mechanisms.

METHODS

The trigeminal, facial, glossopharyngeal and vagus nerves from six fresh cadavers were examined. The length of these nerves from the brainstem to the foramen that they exit were measured. Longitudinal sections were stained and photographed to make measurements. The diameters of the nerves where they exit/enter from/to brainstem, the diameters where the transitional zone begins, the distances to the most distal part of transitional zone from brainstem and depths of the transitional zones were measured. Most importantly, the volume of the central myelin portion of the nerves was calculated. Correlation between length and volume of the central myelin portion of these nerves and the incidences of the corresponding hyperactive dysfunctional syndromes as reported in the literature were studied.

RESULTS

The distance of the most distal part of the transitional zone from the brainstem was 4.19  ±  0.81 mm for the trigeminal nerve, 2.86  ±  1.19 mm for the facial nerve, 1.51  ±  0.39 mm for the glossopharyngeal nerve, and 1.63  ±  1.15 mm for the vagus nerve. The volume of central myelin portion was 24.54  ±  9.82 mm(3) in trigeminal nerve; 4.43  ±  2.55 mm(3) in facial nerve; 1.55  ±  1.08 mm(3) in glossopharyngeal nerve; 2.56  ±  1.32 mm(3) in vagus nerve. Correlations (p  < 0.001) have been found between the length or volume of central myelin portions of the trigeminal, facial, glossopharyngeal and vagus nerves and incidences of the corresponding diseases.

CONCLUSION

At present it is rather well-established that primary trigeminal neuralgia, hemifacial spasm and vago-glossopharyngeal neuralgia have as one of the main causes a vascular compression. The strong correlations found between the lengths and volumes of the central myelin portions of the nerves and the incidences of the corresponding diseases is a plea for the role played by this anatomical region in the mechanism of these diseases.

Cricothyroid approximation for voice and swallowing rehabilitation of high vagal paralysis secondary to skull base neoplasms

This study documents the speech and swallowing outcomes of isolated ipsilateral cricothyroid approximation (aka tensioning thyroplasty; Type IV thyroplasty) for the treatment of high vagal paralysis (combined superior laryngeal nerve and recurrent laryngeal nerve paralysis). This is a pilot study of five cases with high vagal paralysis consequent to skull base neoplasms. Unilateral cricothyroid tensioning sutures were used. In all cases, vocal fold tensioning and vertical realignment of lax vocal folds were achieved. A partial, but acceptable medialization of vocal cord position was achieved. In all cases, aspiration was minimized and normal swallow function was restored by 6 weeks. The voice outcome was excellent in four cases and acceptable in one. Cricothyroid approximation restores vocal fold tension; in addition, it restores vertical vocal fold position and partially restores horizontal vocal fold position. Good voice and swallowing outcomes have been achieved. The procedure is quick, safe, and convenient when combined with a skull-base excision procedure. Further evaluation is merited.

Ocular compression pressure during EEG for the study of increased vagal reactivity

Ocular compression (OC) is a maneuver performed during EEG to demonstrate increased vagal reactivity in children with suspected syncope including breath-holding spells. We examined the relationship between the simulated OC pressure exerted by different physicians and the cardiac slowing responses that they had historically obtained as per EEG records. Simulated OC was performed by each physician using a sphygmomanometer. EEGs were reviewed for the rate of positive cardiac slowing per physician. Among three physicians who performed a total of 73 OC, the mean +/- SD of applied pressure were 29.0 +/- 2.4, 60.7 +/- 3.5 and 42.4 +/- 2.5 mmHg, respectively. There was good intra-physician consistency for the OC pressures exerted. The mean pressure exerted was significantly different between physicians (p < 0.001, ANOVA). The positive response rate for cardiac slowing among these physicians was 11/37 (29.7%), 10/21 (47.6%) and 8/15 (53.3%) respectively. The difference in positive OC responses between physicians was not significant (p = 0.127, chi-square). Higher OC pressures did not translate into more positive responses. A pressure of 30 mmHg is as good as 60 mmHg in demonstrating cardiac slowing during OC.

A carotid artery dissection presenting with dysphagia due to a dilation of upper oesophagus

Carotid and vertebral artery dissection is one of the major causes of ischemic stroke in young patients and diagnosing it remains a challenge for the clinician due to its variable clinical presentation. We report the case of a 57-years old man admitted to the emergency department complaining of dysphagia and a hoarse voice. Physical examination revealed a left deviation of his tong and some weakness of the left side of his soft palate. A gastroscopy and a cervical tomodensitometry revealed the presence of an important dilation of his upper oesophagus. A cerebral magnetic resonance was performed, showing en excentric high signal intensity on the left carotid artery, and the MR angiography confirmed the presence of an acute dissection on the left internal carotid artery. Our patient suffered of a left carotid artery dissection presenting with ipsilateral Xth and XIIth nerve palsies. His main symptom was a dysphagia due to a dilation of his upper oesophagus; the pneumogastric nerve being responsible for the parasympathic innervation of the upper muscles of the oesophagus.

Sympathetic nerve activity and heart rate variability during severe hemorrhagic shock in sheep

INTRODUCTION

In this study we explored direct and indirect measures of autonomic nervous system function, as well as changes in cardiovascular complexity, during hemorrhagic shock (HS).

METHODS

HS was induced in anesthetized sheep (n=8) by removing 40 ml/kg of blood in four 10 ml/kg steps over 40 min. Resuscitation was performed with lactated Ringer's and re-infusion of shed blood. Renal sympathetic nerve activity (RSNA) was measured by microneurography. Spectral analysis of heart rate variability (HRV) employed fast-Fourier transformation of the R-to-R interval (RRI) of the EKG. This generated the normalized high-frequency (HFnu) and low-frequency (LFnu) powers of the RRI, and their ratio (LFnu/HFnu, a proposed index of sympatho-vagal balance). Additionally, non-linear methods were applied: RRI complexity was measured by approximate (ApEn) and sample (SampEn) entropy methods; RRI fractal dimension was measured by curve lengths (FDCL). Plasma catecholamines were determined by HPLC.

RESULTS

The model caused profound HS; 2/8 animals survived till the end of resuscitation. RSNA increased in 7/8 sheep and, as HS progressed, multiple burst complexes were identified followed by sympathetic withdrawal. Concomitant decreases in HFnu and increases in LFnu/HFnu occurred after 20 ml/kg blood loss. ApEn and FDCL decreased after withdrawal of 40 ml/kg of blood. Catecholamine concentrations increased throughout HS. LFnu/HFnu and RSNA were not linearly correlated.

CONCLUSIONS

HS led to an increase in RSNA with subsequent withdrawal. LFnu/HFnu increased during HS in association with vagal withdrawal and loss of RRI complexity. RRI complexity may in part reflect vagal modulation of the heart rate. Changes in directly measured tonic sympathetic traffic do not correlate with non-invasive measures of autonomic modulation of the heart.

Non-invasive measurement of vagus activity in the brainstem - a methodological progress towards earlier diagnosis of dementias?

In Alzheimer's disease (AD), mild functional disturbances should precede gross structural damage and even more clinical symptoms, possibly by decades. Moreover, alterations in the brainstem are supposed to occur earlier as cortical affections. Based on these considerations, we developed a new method aiming at the measurement of vagal brainstem functioning by means of evoked potentials after electrical stimulation of the cutaneous representation of the vagus nerve in the external auditory channel. In the current study, a first sample of patients with Alzheimer's disease (n = 7) and mild cognitive impairment (n = 3) were investigated (6m, 4f, range from 57 to 78 y, mean age 68.6 years). Vagus somatosensory evoked potentials (VSEP) were characterized by significantly longer latencies as compared to healthy age- and gender-matched controls (p < 0.05). Future large scale studies - also including preclinical stages of AD - have to assess the value of this non-invasive, fast and cheap method in the early diagnosis of neurodegenerative disorders.

Facilitation of cardiac vagal activity by CRF-R1 antagonists during swim stress in rats

Exposure to stressors that elicit fear and feelings of hopelessness can cause severe vagal activation leading to bradycardia, syncope, and sudden death. These phenomena though documented, are difficult to diagnose, treat clinically, and prevent. Therefore, an animal model incorporating these cardiovascular conditions could be useful. The present study examined 'sinking' during a 2-h swim stress, a phenomenon that occurs in 50% of rats during 25 degrees C water exposure. Concurrent measurements of body temperature, immobility, heart rate (HR), and PR interval (a measure of vagal activity) were made. Neither decreases in immobility nor variations in hypothermia during swim were correlated with sinking. Bradycardia was more severe in sinking rats (average minimum HR+/-SEM; 143+/-13 vs 247+/-14; p<0.01), and PR interval was elevated (p<0.0001). To examine potential modulation of vagal activity during stress, corticotropin-relasing factor (CRF) receptor antagonists (antalarmin, R121919 and astressin B), a glucocorticoid receptor antagonist (RU486), and a peripherally acting cholinergic antagonist (methylatropine nitrate) were administered. The centrally acting CRF antagonist, antalarmin (32 mg/kg), produced elongation of the PR interval (p<0.0001), robust bradycardia (135+/-18; p<0.001), and increased sinking (92%; p<0.05), and methylatropine nitrate (3.2 mg/kg) blocked these effects. Corroborating these data, two different CRF antagonists, R121919 (30 mg/kg) and astressin B (intracerebroventricular (i.c.v.), 0.03 mug/rat) increased sinking to 100%. RU486 (20 mg/kg) blocked HPA axis negative feedback and decreased percent sinking to 25%. From these studies, we concluded that sinking during a 2-h water exposure was a result of extreme vagal hyperactivity. Furthermore, stress-induced CRF release may serve to protect against elevated cardiac vagal activity.

Is pancreatic polypeptide response to food ingestion a reliable index of vagal function in type 1 diabetes?

OBJECTIVE

The diagnosis of autonomic neuropathy in diabetic patients is based on cardiovascular reflex tests. Since cardiac function may be affected by arteriosclerosis and cardiomyopathy in type 1 diabetes mellitus, alternative tests reflecting vagal nerve function, in other organ systems, are needed. In this study the pancreatic polypeptide (PP) response to a mixed meal was evaluated in healthy subjects and in recently diagnosed type 1 diabetic patients.

MATERIAL AND METHODS

The PP response was studied at different levels of the vagally mediated reflex arch by application of different stimuli: meal ingestion, i.v. edrophonium (a cholinesterase inhibitor) injection and arginine infusion.

RESULTS

Meal ingestion (stimulation of cerebral/vagal level) resulted in a significant and similar PP response in the two groups; i.v. edrophonium injection (stimulating at the second neuron level) resulted in a smaller increase in PP concentrations in the type 1 diabetic patients as compared with the healthy subjects, whereas direct PP-cell stimulation by arginine infusion resulted in similar increments in PP concentrations in the two groups. Thus, in recently diagnosed type 1 diabetic patients with no known manifestations of diabetic neuropathy, the cholinergic second neuron function of the vagal arch to the pancreas is impaired, whereas intrinsic PP-cell function is unaffected.

CONCLUSIONS

This abnormality in cholinergic second neuron function of the vagal reflex arch and the fact that three of the healthy subjects had no increase in PP concentrations at all during the meal test indicates that PP response to a mixed meal is unsuitable for the diagnosis of autonomic neuropathy in type 1 diabetes. The nature of the defect in the second neuron of the vagal innervation of the pancreas in type 1 diabetes remains to be elucidated.

Differential effects of cervical vagosympathetic and mediastinal nerve activation on atrial arrhythmia formation in dogs

To investigate the influence of the thoracic autonomic neuronal hierarchy on atrial arrhythmia formation, we compared the characteristics of atrial tachyarrhythmias induced by electrical stimulation of 1) the right vagosympathetic nerve complex at the cervical level and 2) the more caudal juxta-cardiac mediastinal nerves located on the anterior surface of the superior vena cava. Unipolar electrograms were recorded from 191 sites on the entire epicardial atrial surface and, in some experiments, from 63 right atrial endocardial sites. The sites of origin of initial beats at the onset of atrial tachyarrhythmias so induced were investigated analysing atrial activation maps. Neural effects on repolarization were determined by computing the integral surface subtended by unipolar recordings under basal conditions and at maximum neurally induced bradycardia, and calculating differences at each recording site. The mean area affected by nerve stimulation in all animals was significantly greater in response to vagosympathetic than mediastinal nerve stimulation. Atrial cycle length prolongation prior to tachyarrhythmia onset was more pronounced in response to vagosympathetic than mediastinal nerve stimulation. The earliest epicardial activations in early tachyarrhythmia beats were localized in the right atrial free wall and Bachmann bundle region in both cases, but with a higher incidence of double breakthroughs from septal sites of origin in response to vagosympathetic versus mediastinal nerve stimulation. Sites of early activation were associated with the areas of neurally induced repolarization changes. Thus, differential contributions are made to the electrophysiologic substrate of neurally induced atrial tachyarrhythmias depending on the pattern of engagement of neural elements within the autonomic neuronal hierarchy.

The cold face test: A non-baroreflex mediated test of cardiac vagal function

Application of cold to the face evokes potent bradycardia and a pressor response, similar to the diving reflex. However, the role of the baroreceptors in this response is unclear. Ten healthy controls and two patients with baroreflex impairment were recruited. A cold face test (CFT) was induced by the application of three cold packs (0.5 degrees C) to the face. Heart rate (ECG), blood pressure (Finapres) and skin temperature (forehead electrode) were recorded continuously. All data were analyzed using unpaired Students t-tests, and expressed as mean +/- SD. In all controls, CFT induced bradycardia. The mean onset latency was 5.6 +/- 4.6 s, and the maximal bradycardia was seen at 35.8 +/- 15.8 s. Systolic blood pressure increased in eight controls, with a mean onset latency of 18.8 +/- 16.6 s and a peak rise at 38.7 +/- 22.7 s. In the controls, bradycardia preceded the pressor response. The heart rate and blood pressure changes during CFT had a longer latency than baroreflex evoked responses. Moreover, one subject had bradycardia despite a fall in blood pressure. The two patients had abnormal Valsalva ratios and no change in heart rate during tilt, indicating impairment of the baroreflex. However, both their heart rate and blood pressure responses to CFT were normal. These data are further evidence of the limited role of the baroreflex in the autonomic responses to CFT. They suggest that the CFT may be of use in assessing the integrity of the efferent cardiovascular autonomic pathways in patients with suspected baroreflex impairment.

Relation between myelin area and axon diameter in the aortic depressor nerve of spontaneously hypertensive rats

The hypothesis that the aortic depressor nerve (ADN) from spontaneously hypertensive rats (SHR) does not show the expected correlation between myelin sheath area and the axonal diameter of myelinated fibers detected in normotensive rat myelinated fibers was tested by means of regression analysis. Proximal and distal segments of ADN from 13 normotensive Wistar-Kyoto rats (WKY) and nine SHR were prepared for light microscopy study. With an image analysis system, the area of the myelin sheath and the axonal diameter of all myelinated fibers in each nerve were automatically measured. Regression lines were calculated for all nerve segments from each group. Differences between the regression lines were tested for slope and intercept and differences between the correlation coefficients were also tested. Regression lines for WKY data showed no differences between the proximal and distal segments either for slope or intercept. Proximal and distal SHR regression lines were not coincident between segments or when compared to WKY data. These results agree with previous observations that there are morphological differences between WKY and SHR myelinated fibers of the ADN suggesting that the SHR depressor nerve fibers present characteristics of axonal atrophy and/or remyelination.

Stereotactic radiosurgery for recurrent pleomorphic adenoma invading the skull base--case report--

A 38-year-old man presented with a recurrent pleomorphic adenoma in the parapharyngeal space invading the skull base 19 years after the first operation for a parotid gland tumor. Stereotactic radiotherapy was performed to control the tumor growth using a marginal dose of 8 Gy and maximum dose of 18 Gy with care taken to minimize the dose to nearby structures. The symptoms were reduced within a few months. Magnetic resonance imaging over 5 years showed that the tumor was controlled with no regrowth. Stereotactic radiotherapy is a therapeutic option for the treatment of pleomorphic adenomas.

Vagal dysfunction and the pathogenesis of chronic Chagas disease

Vagal dysfunction is thought to be an early, primary and specific abnormality of chronic Chagas disease. However, chagasic patients with unequivocal evidence of heart disease, can have normal or abnormal vagal control of heart rate. A common explanation for these apparently discordant and contradictory results is proposed.

Impaired vagal modulation of heart rate in individuals with Down syndrome

The attenuated heart rate (HR) and blood pressure (BP) response to exercise in individuals with Down syndrome (DS) has been attributed to autonomic dysfunction, which has been associated with obesity. Our purpose was to determine the role of autonomic control of HR to the attenuated chronotropic response observed in individuals with DS. We evaluated spectral analysis of HR variability (HRV) in 13 individuals with (BMI 32+/-5 kg/m(2), P<0.05) and 14 without DS (BMI 26+/-3 kg/m(2)) by means of 2 min isometric handgrip at 30% of maximal force followed by recovery. Noninvasive measures of HR (ECG) and systolic BP (SBP) (Portapres) were recorded continuously. The increases in HR and SBP, and decrease in high frequency (HF) component were significantly greater in controls than in individuals with DS (P<0.05) during handgrip. The increase in LF/HF ratio was not significantly affected by handgrip and was comparable in both groups. During recovery, the decreases in HR, SBP, and LF/HF ratio, and the increase in HF were significantly greater in controls than in individuals with DS (P<0.05). Controlling for BMI did not alter these results. The attenuated HR and SBP response to the handgrip test in individuals with DS is explained by blunted vagal modulation. Our study suggests that autonomic dysfunction in individuals with DS might be independent of obesity.

Management of vagal paraganglioma: Is operative resection really the best option?

BACKGROUND

Vagal paragangliomas cannot be resected without sacrifice of the vagal nerve. The risk of bilateral vocal cord palsy has been reason to postpone treatment of this benign and slow growing neoplasm in hereditary cases. Postponement could be considered for solitary cases as well.

METHODS

An institute-based review of 48 patients with vagal paragangliomas over the past 30 years was performed.

RESULTS

Forty-eight patients with 58 vagal paragangliomas were studied. All but 4 patients had multiple paragangliomas and should be considered hereditary cases. The 10 patients that underwent an operation lost the vagal nerve; 60% of them had additional cranial nerve palsy postoperatively. In the group of patients who were followed for an average period of 8.5 years, 3 patients (8%) developed cranial nerve palsy.

CONCLUSIONS

Aggressive treatment of vagal paragangliomas leads to unnecessary early loss of vagal nerve function. A period of clinical and radiologic follow-up preceding an operation may lead to prolonged preservation of voice and swallowing functions in these patients, without grave consequences for other lower cranial nerves.

The localization of central pattern generators for swallowing in humans — a clinical-anatomical study on patients with unilateral paresis of the vagal nerve, Avellis’ syndrome, Wallenberg’s syndrome, posterior fossa tumours and cerebellar hemorrhage

BACKGROUND

Our understanding of brainstem swallowing centers is mainly based on experimental animals. In order to solve this problem also in humans, a clinical-anatomical study on dysphagic patients with different lesion patterns was performed.

PATIENTS AND METHODS

We studied 43 consecutively admitted dysphagic patients with unilateral paresis of the vagal nerve (PVN), Avellis' syndrome (AS), Wallenberg's syndrome (WS), posterior fossa tumour (PFT) or cerebellar hemorrhage (CH) with regard to clinical and anatomical aspects.

FINDINGS

There was a continuum with regard to functional outcome from neurogenic dysphagia (ND): Patients with PFT or CH had a significantly worse outcome than patients with WS; the outcome of WS patients was significantly worse than that of patients with PVN or AS. In AS only the Nucleus ambiguus (NA) and its surrounding reticular formation (RF) were affected. In all patients with WS, the infarctions of the dorsolateral medulla were situated in the rostral third of the medulla and affected the NA and the Nucleus tractus solitarii (NTS) with their surrounding RF. In patients with PFT and CH, the NTS and its surrounding RF were affected on both sides. The overlap area of WS and PFT lesions is situated in the NTS and the surrounding RF, especially in its Nucleus parvocellularis.

INTERPRETATION

Our results point to the fact, that in humans the dorsomedial central pattern generators (CPGs) for swallowing are situated in the rostral part of the dorsal medulla oblongata near the NTS/surrounding RF (especially Nucleus parvocellularis) and that the dorsomedial CPGs are superior to the ventrolateral CPGs (near the NA/surrounding RF) with regard to their swallowing-relevance. Furthermore, we hypothesize that due to the individual asymmetry of the swallowing-dominant forebrain hemisphere - the outcome from ND in WS depends on the side of the medullary infarction.

[Autonomic cardiovascular regulation in patients with tics and Tourette syndrome]

Autonomic cardiovascular regulation has been assessed in patients aged 4-15 years with Tourette syndrome (n = 22) and other tic disorders (n = 48). Symptom significance was estimated by a number of hyperkinetic episodes per 20 minutes, tic scale and variants of the disease course. The functional condition of autonomic nervous system was studied clinically and using spectral analysis of heart rate variability in both upright and supine positions. Negative correlation between the ratio of sympathetic and vagus influences and severity of the disease was found: the severer were tic symptoms, the stronger was a trend to vagotonia (beta = -0.36; p < 0.0025; F > 4.0). In orthostatic test, patients with Tourette syndrome demonstrated an unfavorable hypersympathicotonic type of cardiovascular system reaction. Patients were treated during 4 weeks with glycinum (0.2 +/- 0.1 mg/day), phenibutum (0.5 +/- 0.25 mg/day), clonazepam (1.5 +/- 0.5 mg/day), tiapride (200 +/- 100 mg/day), haloperidol (1-1.5 mg/day), rispolept (2 mg/day). There was no negative effect of the drugs on heart rate variability. On the contrary, the therapy reduced hyperkinetic symptoms and corrected autonomic influences on the sinus rhythm. It is suggested that changes in autonomic cardiovascular regulation might be of secondary character and do not need any special correction.

Discordant mental and physical efforts in an autistic patient

We investigated whether there was mental effort in response to verbal commands in a 16-year old girl with autism, a high degree of non-compliance with commands and symptoms of autonomic dysfunction by monitoring the brainstem autonomic tone during an attempt to perform isometric exercise. An index of cardiac vagal tone (CVT), cardiac sensitivity to baroreflex (CSB), heart rate (HR) and mean arterial blood pressure (MAP) were measured simultaneously. Physical non-compliance with our commands meant there was no force applied by the patient during the attempted exercise, but CVT and CSB were both reduced and sustained at very low levels throughout the attempt, while MAP and HR were increased concurrently to higher levels in the same period. This vagal withdrawal to allow concurrent increases in HR and MAP is an arousal response appropriate for isometric exercise, which is a sign of a positive mental effort to comply with our commands. These results demonstrate discordant mental and physical efforts in our patient. In this particular case, the physical inabilities in some instances could have been mislabelled as mental non-compliance due to autism. It would be worthwhile to investigate the prevalence of discordant mental and physical efforts in autism.

A case of cervical paraganglioma: usefulness of FDG PET imaging and a possibility of rare origination

Cervical paragangliomas are rare tumors derived from neural crest cells. Anatomic imaging techniques rely upon the characteristic spatial relations and the high vascularity of this tumor. Results of computed tomography (CT), magnetic resonance imaging (MRI), and arteriography initially led us to the preoperative diagnosis of cervical paraganglioma. In our case, 2-[18F]-fluoro-2-deoxy-D-glucose positron emission tomography (FDG PET), a type of functional imaging, was also carried out and demonstrated abnormally increased tracer uptake; this approach was thus successful for visualizing paraganglioma. FDG PET imaging may be useful in the detection of benign paraganglioma. On surgical exploration of the neck, the tumor was found to arise from the vagus nerve, whereas the hypoglossal nerve was encompassed by the tumor in its upper portion. The intraoperative findings suggested the possibility that the tumor had arisen from the hypoglossal nerve.

Cardiovascular autonomic control in myotonic dystrophy type 1: a correlative study with clinical and genetic data

The autonomic nervous system has been evaluated in myotonic dystrophy with contradictory results and its relationship with heart disturbances remains unclear. Twenty-three patients with myotonic dystrophy type 1 were investigated by a battery of six cardiovascular autonomic tests and power spectral analysis of heart rate variability. Although 15 patients (65%) revealed abnormal or borderline results in some tests, only one patient had a definite autonomic damage, as indicated by two or more abnormal tests. As a group, myotonic dystrophy type 1 patients showed a significant reduction of heart rate variability during deep breathing (P < 0.0001). The exclusive involvement of parasympathetic tests suggests that a mild vagal dysfunction occurs in some myotonic dystrophy type 1 patients. The results indicate that such autonomic abnormalities are not: (1) part of a peripheral neuropathy; (2) related to cytosine-thymine-guanine repeat size or breathing pattern. Power spectral analysis showed a reduction of supine low-frequency band, which is, but not exclusively, a marker of sympathetic activity. It was inversely correlated to disease duration (P < 0.04), suggesting a progression as the disease advances. A low-frequency power, recorded after standing, was significantly associated (P < 0.02) with presence of heart involvement. Our findings suggest that a mixed, especially parasympathetic, autonomic dysfunction may occur in myotonic dystrophy type 1, although it is not a major finding. It could play a role in the occurrence of cardiac abnormalities, or increase the risk of sudden cardiovascular events.

Effects of glucagon-like peptide-1 and feeding on gastric volumes in diabetes mellitus with cardio-vagal dysfunction

Glucagon-like peptide-1 (GLP-1) increases gastric volume in humans possibly through the vagus nerve. Gastric volume response to feeding is preserved after vagal denervation in animals. We evaluated gastric volume responses to GLP-1 and placebo in seven diabetic patients with vagal neuropathy in a crossover study. We also compared gastric volume response to feeding in diabetes with that in healthy controls. We measured gastric volume using SPECT imaging. Data are median (interquartile range). In diabetic patients, GLP-1 did not increase gastric volume during fasting [5 mL (-3; 30)] relative to placebo [4 mL (-14; 50) P = 0.5], or postprandially [Delta postprandial minus fasting volume 469 mL (383; 563) with GLP-1 and 452 mL (400; 493) with placebo P = 0.3]. Change in gastric volume over fasting in diabetic patients on placebo was comparable to that of healthy controls [452 mL (400; 493)], P = 0.5. In contrast to effects in health, GLP-1 did not increase gastric volume in diabetics with vagal neuropathy, suggesting GLP-1's effects on stomach volume are vagally mediated. Normal gastric volume response to feeding in diabetics with vagal neuropathy suggests that other mechanisms compensate for vagal denervation.

Impaired cardiovagal and vasomotor responses to baroreceptor stimulation in type II diabetes mellitus

BACKGROUND

In diabetic patients, impairment of the cardiovagal limb of the baroreflex has been well established. However, the role of sympathetic mediated baroreflex vasomotor control of the blood vessels is not well defined. We therefore assessed the vasomotor responses to sinusoidal baroreceptor stimulation in diabetic patients.

MATERIALS AND METHODS

We studied 14 type II diabetic patients (age; 57 +/- 7 years) and 18 healthy controls (age; 59 +/- 11 years). Oscillatory neck suction was applied at 0.1 Hz to assess the sympathetic modulation of the heart and blood vessels, and at 0.2 Hz to assess the effect of parasympathetic stimulation on the heart. Breathing was paced at 0.25 Hz. Spectral analysis was used to evaluate the oscillatory responses of RR-interval and blood pressure.

RESULTS

The diabetic patients showed a significantly lower RR-interval response (P < 0.05) to the 0.1 Hz neck suction (2.52 +/- 0.50-3.62 +/- 0.54 ln ms2) than the controls (4.23 +/- 0.31-6.74 +/- 0.36 ln ms2). The increase in power of 0.1 Hz systolic blood pressure oscillations during 0.1 Hz suction was also significantly smaller (P < 0.05) in the diabetics (1.17 +/- 0.44-1.69 +/- 0.44 mmHg2) than in the controls (1.60 +/- 0.29 mmHg2-5.87 +/- 1.25 mmHg2). The magnitude of the peak of the 0.2 Hz oscillation in the RR-interval in response to 0.2 Hz neck stimulation was significantly greater (P < 0.05) in the controls (3.42 +/- 0.46 ln ms2) than in the diabetics (1.58 +/- 0.44 ln ms2).

CONCLUSION

In addition to cardiovagal dysfunction, baroreflex-mediated sympathetic modulation of the blood vessels is impaired in type II diabetic patients.

Abnormal PI3 kinase/Akt signal pathway in vagal afferent neurons and vagus nerve of streptozotocin-diabetic rats

The PI3 (phosphatidylinositol-3) kinase/Akt (protein kinase B) signal pathway is involved in the molecular signaling that regulates retrograde axonal transport of neurotrophins in the nervous system. Previous work showed that a reduced retrograde axonal transport of endogenous nerve growth factor (NGF) and neurotrophin-3 (NT-3) in the vagus nerve of diabetic rats occurred in the presence of normal production of neurotrophins and neurotrophin receptors. To assess the potential involvement of an impaired PI3 kinase/Akt signal pathway in the diabetes-induced reduction in retrograde axonal transport of neurotrophins in the vagus nerve, we characterized diabetes-induced changes in the PI3 kinase/Akt signal pathway in the vagus nerve and vagal afferent neurons. Control and streptozotocin (STZ)-induced diabetic rats with a duration of 16 weeks, kinase assays, Western blotting, and immunocytochemistry were used to show that diabetes resulted in alterations in activity and protein expression of the PI3 kinase/Akt signal pathway in the vagus nerve and vagal afferent neurons. Diabetes caused a significant decrease in enzymatic activity of PI3 kinase and Akt (52 and 36% of control, respectively) in the vagus nerve. The reduced enzymatic activity was not associated with decreased protein expression of the p85 subunit of PI3 kinase, Akt and phosphorylation of Akt (ser473). In contrast, there was a significant increase in the phosphorylation of p70s6 kinase (thr421/ser424) along with a normal protein expression of p70s6 kinase in the vagus nerve of diabetic rats. However, diabetes induced an overall decrease in immunoreactivity of the p85 subunit of PI3 kinase, phospho-Akt (ser473) and phospho-p70s6/p85s6 kinase (thr421/ser424) in vagal afferent neurons. Thus, impaired PI3 kinase/Akt signal pathway may partly account for the reduced retrograde axonal transport of neurotrophins in the vagus nerve of STZ-induced diabetic rats.

Vagal function in health and disease: studies in Pittsburgh

The integration of behavioral processes with changes in vagally-controlled heart rate has been the focus of our investigations. A series of studies is reviewed showing that central and peripheral response inhibition is a primary source of transient, vagally-induced cardiac slowing during information processing. Individual differences in such responses are then shown to relate to the amplitude of cardiovascular responses to stressors. Overall, the specificity and sensitivity of vagal responses to higher level cortical function is supported by our research.

A case of trigeminal-vagal neuralgia relieved by peripheral self-stimulation

A case of simultaneous trigeminal and vagoglossopharyngeal neuralgia is described. No microvascular compression was seen at the trigeminal complex while the origin of vagoglossopharyngeal pain could have been due either to Chiari malformation or microvascular compression of the IX-X nerve complex. Decompressive surgery was ineffective. The patient could completely block his facial painful fits by strongly pinching the anterior axillary fold. This case militates against peripheral theories of facial neuralgias, including microvascular compression and ganglion ignition focus theories, and supports a central origin thereof.

Selective vagal afferent dysfunction in dogs with congenital idiopathic megaoesophagus

Congenital idiopathic megaoesophagus (CIM) is a rare, naturally occurring disorder of the dog that is characterised by deficient motility and dilatation of the oesophagus. Recent studies indicate that the vagal sensory system mediating reflexes induced by oesophageal distension is defective in, and may underlie the pathomechanism of this disorder. We sought to establish whether other distension sensitive vagal afferent systems were impaired in CIM, or whether the vagal afferent dysfunction was selective. Thus, we examined the Hering-Breuer lung inflation reflex (HBR), which is subserved by a contiguous and physiologically similar vagal afferent system, in five dogs with CIM in which oesophageal vagal afferent dysfunction had been demonstrated. At varying levels of lung inflation, we found the HBR to be normally graded and of normal strength in affected dogs and that this result was unlikely to be influenced by other factors known to alter the strength of the reflex. These observations provide evidence for an organ specific, selective vagal afferent dysfunction in dogs with CIM. It is possible that similar processes may be active in disorders of visceral organ systems subserved by vagal afferents in other species, including man.

[Vagal hyperreactivity and sudden infant death. Study of 15 families]

Prone sleep position is obviously the main risk factor for sudden infant death. Other risk factors, such as vagal overactivity particularly in the familial form, are still discussed. We here report 15 families characterized by the coexistence of vagal overactivity and sudden infant death. At least, 1 child for each family had documented [Holter or occulo-cardiac reflex (OCR)] vagal overactivity. In 5 families 2 children were affected; in 2 families 3 children were affected and in 1 family 4 children were affected. Sudden death occurred in the elderly of the family in 8 cases, in the twin in 3 cases, in the 2nd in 3 cases and in the 5th child in 1 case. Within the 15 families, at least 1 parent had experienced vagally-induced fainting or syncope in 10 cases. Familial pattern of vagal overactivity is underlined. Possible links between vagal overactivity, risk factor for suddden death and sudden death are discussed. We suggest an Holter-ECG and OCR follow-up for sudden infant death siblings with history of familial vagal overactivity (3 examinations during the 1st year of life, at 1, 3 and 9 months).

New findings on the neuropathology of multiple system atrophy

Multiple system atrophy (MSA) provides a typical example of the integrative role of the central autonomic network in controlling cardiovascular, respiratory, bladder and gastrointestinal functions. There is increasing evidence that neurochemically defined neuronal groups of the brainstem are selectively affected in MSA to a much greater degree than in Parkinson's disease. These include the catecholaminergic neurons of the rostral ventrolateral medulla (C1 group) which project to the intermediolateral cell column and are involved in modulation of sympathetic vasomotor outflow, and noradrenergic neurons of the caudal ventrolateral medulla (A1 group) projecting to the magnocellular nuclei of the hypothalamus and regulating vasopressin (AVP) release. Loss of these groups of neurons may, at least in part, explain the development of orthostatic hypotension, baroreflex dysfunction, and impaired reflex AVP release in response to hypotension. There is preliminary evidence that cardiovagal neurons of the ventrolateral portion of the nucleus ambiguus, distinct from the branchimotor neurons of the compact region, may also be affected in MSA. Loss of cholinergic neurons in the medullary arcuate nucleus, considered by some to be the homologous to the central chemosensitive region of the ventral medullary surface, may contribute to disturbances in automatic ventilation, particularly during sleep, in patients with MSA.

Neurotrophin-4 deficient mice have a loss of vagal intraganglionic mechanoreceptors from the small intestine and a disruption of short-term satiety

Intraganglionic laminar endings (IGLEs) and intramuscular arrays (IMAs) are the two putative mechanoreceptors that the vagus nerve supplies to gastrointestinal smooth muscle. To examine whether neurotrophin-4 (NT-4)-deficient mice, which have only 45% of the normal number of nodose ganglion neurons, exhibit selective losses of these endings and potentially provide a model for assessing their functional roles, we inventoried IGLEs and IMAs in the gut wall. Vagal afferents were labeled by nodose ganglion injections of wheat germ agglutinin-horseradish peroxidase, and a standardized sampling protocol was used to map the terminals in the stomach, duodenum, and ileum. NT-4 mutants had a substantial organ-specific reduction of IGLEs; whereas the morphologies and densities of both IGLEs and IMAs in the stomach were similar to wild-type patterns, IGLEs were largely absent in the small intestine (90 and 81% losses in duodenum and ileum, respectively). Meal pattern analyses revealed that NT-4 mutants had increased meal durations with solid food and increased meal sizes with liquid food. However, daily total food intake and body weight remained normal because of compensatory changes in other meal parameters. These findings indicate that NT-4 knock-out mice have a selective vagal afferent loss and suggest that intestinal IGLEs (1) may participate in short-term satiety, probably by conveying feedback about intestinal distension or transit to the brain, (2) are not essential for long-term control of feeding and body weight, and (3) play different roles in regulation of solid and liquid diet intake.

Sensory neuropathy of the trigeminal, glossopharyngeal, and vagal nerves in Sjögren's syndrome

Isolated cranial nerve involvement in primary Sjögren's syndrome (primary SS) has rarely been described. We report the case of a patient with sensory neuropathy of the trigeminal and also the glossopharyngeal and vagal nerves, which has not been identified previously. The electrophysiological findings in our patient with primary SS confirmed trigeminal sensory neuropathy with abnormal blink reflexes and abnormal cutaneous masseter inhibitory reflexes.

Neurogenic hypertension. A new MRI protocol for the evaluation of neurovascular compression of the cranial nerves IX and X root-entry zone

OBJECTIVE

Neurovascular compression of the rostral ventrolateral medulla (RVLM) has been implicated in the pathogenesis of essential hypertension. Although MRI has been widely used to evaluate the morphologic relation of structures in this region, spatial resolution of the previously used techniques was limited. This article describes the use of a new MRI protocol that combines two sequences with improved spatial resolution and complementary image information as well as a set of defined criteria for image analysis.

METHODS

MRI of the brain stem was performed in 60 hypertensive and 50 normotensive subjects using a 3D-CISS and a 3D-FISP-MRA sequence. Neurovascular contact in the RVLM was independently assessed by four readers using predefined criteria and compared with a consensus finding. Agreement was expressed by kappa statistics on a 0 to 1 scale.

RESULTS

Left-sided neurovascular contact within the RVLM was found in 13 (22%) hypertensive and 6 (12%) control subjects. The inter-reader agreement for positive and negative findings ranged from 0.47 to 0.79; agreement to the consensus finding ranged from 0.65 to 0.90.

CONCLUSIONS

The combination of 3D-CISS and arterial flow-sensitive 3D-FISP, together with the evaluation criteria defined in this study, can be used for describing the finer anatomic features of the brain stem, and in particular for investigation of neurovascular contact of the IX/X cranial nerve root-entry zone. The high quality of images and the substantial or almost perfect reader-consensus agreement should make this protocol useful for future investigations of the neurovascular compression syndrome in patients with essential hypertension and possibly in other neurovascular compression syndromes, such as trigeminal neuralgia and hemifacial spasm.