Epithelial plasticity enhances regeneration of committed taste receptor cells following nerve injury.

Taste receptor cells are taste bud epithelial cells that are dependent upon the innervating nerve for continuous renewal and are maintained by resident tissue stem/progenitor cells. Transection of the innervating nerve causes degeneration of taste buds and taste receptor cells. However, a subset of the taste receptor cells is maintained without nerve contact after glossopharyngeal nerve transection in the circumvallate papilla in adult mice. Here, we revealed that injury caused by glossopharyngeal nerve transection triggers the remaining differentiated K8-positive taste receptor cells to dedifferentiate and acquire transient progenitor cell-like states during regeneration. Dedifferentiated taste receptor cells proliferate, express progenitor cell markers (K14, Sox2, PCNA) and form organoids in vitro. These data indicate that differentiated taste receptor cells can enter the cell cycle, acquire stemness, and participate in taste bud regeneration. We propose that dedifferentiated taste receptor cells in combination with stem/progenitor cells enhance the regeneration of taste buds following nerve injury.

Parálisis facial periférica posterior a bloqueo de glosofaríngeo: reporte de un caso / Peripheral facial palsy following glossopharyngeal block: a case report

La neuralgia del nervio glosofaríngeo es una entidad clínica dolorosa, secundaria a diferentes etiologías de carácter compresivo sobre el nervio. Puede llegar a generar un deterioro importante sobre la calidad de vida por sus síntomas sensitivos a nivel facial, siendo menos frecuente que la neuralgia del nervio trigémino y requiriendo el cumplimiento de criterios diagnósticos para su confirmación clínica. El tratamiento de esta entidad puede ser farmacológico, quirúrgico o intervencionista por vía percutánea con guía ecográfica. Las complicaciones de las técnicas intervencionistas son poco frecuentes. En este caso se presenta una parálisis facial periférica, con resolución completa en 12 horas posterior a un bloqueo percutáneo del nervio glosofaríngeo con guía ecográfica. Esta complicación muy poco reportada en la literatura médica puede deberse a la difusión local del medicamento anestésico o las múltiples variantes anatómicas del nervio facial, además de la posibilidad de ramas extra petrosas que comunican al nervio facial con el glosofaríngeo. Se puede considerar a la parálisis facial periférica un efecto secundario esperado, poco frecuente de este procedimiento en pacientes con variantes anatómicas, que no modifica la efectividad de la intervención o la seguridad del paciente.(AU)

Glossopharyngeal nerve neuralgia is a painful clinical entity, secondary to different etiologies of compressive character on the nerve. It can generate an important deterioration in the quality of life, due to its sensitive symptoms at the facial level; being less frequent than trigeminal nerve neuralgia, and requiring the fulfillment of diagnostic criteria for its clinical confirmation. The treatment of this entity can be pharmacological, surgical, or interventional by percutaneous route with ultrasound guidance. Complications of interventional techniques are rare, in this case, we present peripheral facial paralysis; with complete resolution in 12 hours after a percutaneous block of the glossopharyngeal nerve with ultrasound guidance. This complication is very rarely reported in the medical literature may be due to the local diffusion of the anesthetic drug or the multiple anatomical variants of the facial nerve in addition to the possibility of extra petrosal branches that communicate the facial nerve with the glossopharyngeal nerve. Peripheral facial paralysis can be considered an expected side effect, infrequent of this procedure in patients with anatomical variants, which does not modify the effectiveness of the intervention or the patient’s safety.(AU)

Anatomic features of the fetal round and oval windows, and their relations with the tympanic nerve.

OBJECTIVE: The study aimed to examine morphometric properties of the round window (RW) and oval window (OW) and to show their relation with the tympanic nerve (the Jacobson's nerve, JN) in human fetuses from the otologic surgeon's perspective. METHODS: Thirty temporal bones of 15 fetal cadavers (8 males, 7 females) aged with 24.40 ± 3.71 weeks were included in the study. The height, width and surface area of the RW and OW and also distance from the JN to the OW and RW were measured. RESULTS: The height, width and surface area of the RW in this work were measured as 1.48 ± 0.25 mm, 1.57 ± 0.37 mm, and 2.05 ± 0.69 mm2, respectively. The RW was detected as round-shaped (8 cases, 26.7%), oval-shaped (15 cases, 50%), and dome-shaped (7 cases, 23.3%). The height, width and surface area of the OW were measured as 1.42 ± 0.26 mm, 2.90 ± 0.44 mm, and 3.63 ± 0.74 mm2, respectively. The OW was observed as oval-shaped (15 cases, 50%), kidney-shaped (10 cases, 33.3%), D-shaped (4 cases, 13.3%), and trapezoid-shaped (1 case, 3.3%). The JN was found 1.21 ± 0.60 and 1.18 ± 0.54 mm away from the RW and OW, respectively. CONCLUSION: This study containing morphological data about the shapes, diameters and area of the RW and OW may be useful to predict surgical difficulty, and to select implants of suitable size preoperatively for the windows. Knowing the relationship between the JN and the windows can be helpful to avoid iatrogenic injuries of the nerve.

Post-tonsillectomy dysphagia secondary to glossopharyngeal nerve injury.

The glossopharyngeal nerve lies in close proximity to the tonsillar fossa making it susceptible to injury during tonsillectomy, though it is uncommonly injured in practice. We present a case of severe dysphagia due to glossopharyngeal nerve injury following tonsillectomy and demonstrate the efficacy of the McNeill Dysphagia Therapy Program (MDTP), a novel stepwise exercise-based rehabilitation program, in improving clinical outcomes. In patients with persistent, severe dysphagia following tonsillectomy, glossopharyngeal nerve injury should be on the differential diagnosis. The MDTP is one method by which clinicians may be able to treat this complex condition.

Factors affecting the approaches and complications of surgery in childhood papillary thyroid carcinomas.

BACKGROUND: The aim of the study is to analyse the factors related to permanent surgical complications in children and adolescents with papillary thyroid carcinoma treated by total thyroidectomy with central and bilateral neck dissections. METHODS: Children and adolescents aged ≤18-year-old at presentation with papillary thyroid carcinoma during the years 1988-2010 underwent thyroid and lymph-node surgeries (with a median follow-up of 19.6 years) were analysed for post-surgical complications. RESULTS: Permanent surgical morbidity occurred in 14% (n = 70) of patients who underwent total thyroidectomy as well as bilateral central and lateral neck dissections (n = 509). Factors associated with permanent complications included pN1 with extra-nodal extension, > 4 metastatic lymph nodes in the central neck compartment, presence of distant metastases and younger age of patients at surgery. Patients who received extensive surgery had better relapse-free survival rates (p < 0.001). CONCLUSION: Total thyroidectomy and bilateral central as well as lateral neck dissections for children and adolescents with papillary thyroid carcinoma was associated with substantial postoperative complications. Nevertheless, it is associated with better prognosis for young patients with thyroid cancer. Prophylactic compartment-oriented lymph node dissections to these patients could be the management protocol in experienced hands.

A case of varicella zoster encephalitis with glossopharyngeal and vagus nerve injury as primary manifestation combined with medulla lesion.

Varicella zoster virus (VZV) can invade the brainstem or brain via the glossopharyngeal, vagus , or facial nerve, resulting in brainstem inflammation or encephalitis. We report the case of a 66-year-old male patient with a primary manifestation of medulla injury of the glossopharyngeal and vagus nerves, combined with a medulla lesion, who was misdiagnosed with lateral medullary syndrome. Facial nerve injury and earache subsequently occurred and human herpes virus 3 (VZV) was detected by second-generation sequencing of the cerebrospinal fluid. The final diagnosis was varicella zoster encephalitis, which improved after antiviral therapy.

A New Neuropathologic Mechanism of Blood pH Irregularities After Neck Trauma: Importance of Carotid Body-Glossopharyngeal Nerve Network Degeneration.

OBJECTIVE: We created a neck trauma model by injecting blood into the sheath of rabbits' carotid bodies (CBs). Then we determined the relationship between neuronal degeneration of the CB due to hemorrhage of this organ and its clinical effects such as blood pH and heart rhythm. METHODS: The present study included 24 adult male New Zealand rabbits. The animals were divided into 3 groups: control (n = 5); sham (0.5 mL saline injected into CBs; n = 5); and study (CB trauma model; n = 14). pH values and heart rhythms were recorded before the experiment to determine the values under normal conditions, and measurements were repeated thrice in the days following the experiment. The number of normal and degenerated neuron density of CBs was counted. The relationship between the blood pH values, heart rhythms, and degenerated neuron densities was analyzed. RESULTS: Heart rhythms were 218 ± 20 in the control group, 197 ± 16 in the sham group (P = 0.09), and 167 ± 13 in the study group (P < 0.0005). pH values were 7.40 ± 0.041 in the control group, 7.321 ± 0.062 in the sham group (P = 0.203), and 7.23 ± 0.02 in study group (P < 0.0005). Degenerated neuron densities were 12 ± 4/mm3 in the control group, 430 ± 74/mm3 in the sham group (P < 0.005), and 7434 ± 810/mm3 in the study group (P < 0.0001). CONCLUSIONS: A high degenerate neuron density in the CB can decrease blood pH and hearth rhythm after neck trauma, and there might be a close relationship between the number of degenerated neurons and clinical findings (such as heart rhythm and blood pH). This relationship suggests that injury to the glossopharyngeal nerve-CB network can cause acidosis by disturbing the breathing-circulating reflex and results in respiratory acidosis.

Bilateral carotid sinus nerve transection exacerbates morphine-induced respiratory depression.

Opioid-induced respiratory depression (OIRD) involves decreased sensitivity of ventilatory control systems to decreased blood levels of oxygen (hypoxia) and elevated levels of carbon dioxide (hypercapnia). Understanding the sites and mechanisms by which opioids elicit respiratory depression is pivotal for finding novel therapeutics to prevent and/or reverse OIRD. To examine the contribution of carotid body chemoreceptors OIRD, we used whole-body plethysmography to evaluate hypoxic (HVR) and hypercapnic (HCVR) ventilatory responses including changes in frequency of breathing, tidal volume, minute ventilation and inspiratory drive, after intravenous injection of morphine (10 mg/kg) in sham-operated (SHAM) and in bilateral carotid sinus nerve transected (CSNX) Sprague-Dawley rats. In SHAM rats, morphine produced sustained respiratory depression (e.g., decreases in tidal volume, minute ventilation and inspiratory drive) and reduced the HVR and HCVR responses. Unexpectedly, morphine-induced suppression of HVR and HCVR were substantially greater in CSNX rats than in SHAM rats. This suggests that morphine did not compromise the function of the carotid body-chemoafferent complex and indeed, that the carotid body acts to defend against morphine-induced respiratory depression. These data are the first in vivo evidence that carotid body chemoreceptor afferents defend against rather than participate in OIRD in conscious rats. As such, drugs that stimulate ventilation by targeting primary glomus cells and/or chemoafferent terminals in the carotid bodies may help to alleviate OIRD.

Mechanisms Involved in Guiding the Preference for Fat Emulsion Differ Depending on the Concentration.

High-fat foods tend to be palatable and can cause addiction in mice via a reinforcing effect. However, mice showed preference for low fat concentrations that do not elicit a reinforcing effect in a two-bottle choice test with water as the alternative. This behavior indicates the possibility that the mechanism underlying fat palatability may differ depending on the dietary fat content. To address this issue, we examined the influences of the opioid system and olfactory and gustatory transductions on the intake and reinforcing effects of various concentrations of a dietary fat emulsion (Intralipid). We found that the intake and reinforcing effects of fat emulsion were reduced by the administration of an opioid receptor antagonist (naltrexone). Furthermore, the action of naltrexone was only observed at higher concentrations of fat emulsion. The intake and the reinforcing effects of fat emulsion were also reduced by olfactory and glossopharyngeal nerve transections (designated ONX and GLX, respectively). In contrast to naltrexone, the effects of ONX and GLX were mainly observed at lower concentrations of fat emulsion. These results imply that the opioid system seems to have a greater role in determining the palatability of high-fat foods unlike the contribution of olfactory and glossopharyngeal nerves.

Bilateral glossopharyngeal nerve palsy following tonsillectomy: a very rare and difficult complication of a common procedure.

OBJECTIVES: Tonsillectomy is one of the most commonly performed otolaryngological procedures. Bilateral palsy of the glossopharyngeal nerve is an exceedingly rare complication that can result in significant morbidity. This case report aimed to raise awareness of this complication and outline management strategies. CASE REPORT: A 31-year-old woman who underwent routine tonsillectomy presented with progressive numbness of the palate, dysgeusia, xerostomia, paraesthesia of the tongue and the feeling of something in her throat within 2 weeks of surgery. She reported the post-operative onset of snoring. Examination revealed a symmetrically low, 'dropped' soft palate. Over time, her symptoms have lessened, but dysgeusia and snoring remain. CONCLUSION: The position of the glossopharyngeal nerve in the tonsillar bed makes it prone to injury during tonsillectomy, especially if 'hot' methods are used. Bilateral injury can result in significant morbidity that can be difficult to treat. Patients should be warned about this risk and care should be taken to minimise it.

Glossopharyngeal nerve and vagus nerve palsies associated with influenza vaccination.

We herein report the first case of glossopharyngeal nerve and vagus nerve palsies that appeared after an influenza vaccination. A 15-year-old boy developed dysphagia and dysarthria seven days after receiving an inoculation of the inactivated influenza vaccine. Massive intravenous immunoglobulin (IVIg) treatment was applied, as the patient's symptoms were considered to be immunological adverse effects of the influenza vaccine. He responded well to IVIg, and the symptoms immediately diminished. The mechanisms underlying the development of neurologic symptoms following vaccination are difficult to determine; however, providing immediate immunological treatment, such as IVIg, is effective and beneficial in countering these symptoms.

A 3D cone beam computed tomography study of the styloid process of the temporal bone.

BACKGROUND: To investigate the length and three-dimensional orientation and to detail the morphological variations of the styloid process. MATERIALS AND METHODS: Forty-four patients undergoing temporal bone evaluation for different reasons were randomly selected and included in the present study. The length, angulation in the coronal and sagittal planes, as well as morphological variations of the styloid processes were assessed using conebeam computer tomography. Pearson's correlation coefficient was used to test possible associations between the length of styloid process and angulations, as well as between angulations. Student's t-test was used to compare the differences between the sample mean length and angulations in normal and elongated styloid process groups. RESULTS: The sagittal angle showed weak positive correlations with the styloid process length and the transverse angle (r = 0.24, p = 0.02, n = 88). A medium positive correlation was found between the sagittal and transverse angulations in the elongated styloid process group (r = 0.49, p = 0.0015, n = 38). There was a statistical significant difference between the mean sagittal angulation in elongated styloid and normal styloid process groups (p = 0.015). The styloid process morphology also varied in terms of shape, number, and degree of ossification. CONCLUSIONS: The morphometric and morphologic variations of the styloid process may be important factors to be taken into account not only from the viewpoint of styloid syndromes, but also in preoperatory planning and during surgery.

Vernet's syndrome after carotid endarterectomy.

Unilateral paresis of cranial nerves IX to XI is defined as Vernet's syndrome. We retrospectively assessed cranial nerve symptoms from the clinical records of 143 carotid endarterectomy patients. A flexible nasolaryngoscope was used to examine vocal fold movements in 73 patients. If vocal fold paresis (VFP) was confirmed, the patient also underwent magnifying laryngoscopy (for correct diagnosis of injury to the glossopharyngeal and vagus nerves). It was found from clinical records that 8 patients (6%) were confirmed to have cranial nerve symptoms corresponding to Vernet's syndrome; 7 patients (9 %) had VFP on nasolaryngoscopy. In 2 patients, magnifying laryngoscopy confirmed ipsilateral VFP, pharyngeal paresis, pharyngeal wall hypesthesia, and ipsilateral pharyngeal wall swelling. These 2 patients also had symptoms of injury to the accessory nerve. Damage to cranial nerves IX to XI probably occurred in the parapharyngeal space, based on the existence of posterior pharyngeal wall edema or swelling after carotid endarterectomy.

Glossopharyngeal nerve transection impairs unconditioned avoidance of diverse bitter stimuli in rats.

There is growing evidence of heterogeneity among responses to bitter stimuli at the peripheral, central and behavioral levels. For instance, the glossopharyngeal (GL) nerve and neurons receiving its projections are more responsive to bitter stimuli than the chorda tympani (CT) nerve, and this is particularly true for some bitter stimuli like PROP & cycloheximide that stimulate the GL to a far greater extent. Given this information, we hypothesized that cutting the GL would have a greater effect on behavioral avoidance of cycloheximide and PROP than quinine and denatonium, which also stimulate the CT, albeit to a lesser degree than salts and acids. Forty male SD rats were divided into four surgery groups: bilateral GL transection (GLX), chorda tympani transection (CTX), SHAM surgery, and combined transection (CTX + GLX). Postsurgical avoidance functions were generated for the four bitter stimuli using a brief-access test. GLX significantly compromised avoidance compared to both CTX and SHAM groups for all stimuli (p < .02), while CTX and SHAM groups did not differ. Contrary to our hypothesis, GLX had a greater effect on quinine than cycloheximide (mean shift of 1.02 vs. 0.27 log10 units). Moreover, combined CTX + GLX transection shifted the concentration-response function further than GLX alone for every stimulus except cycloheximide (ps < .03), suggesting that the GSP nerve is capable of maintaining avoidance of this stimulus to a large degree. This hypothesis is supported by reports of cycloheximide-responsive cells with GSP-innervated receptive fields in the NST and PBN.

Taste function evaluation after tonsillectomy: a prospective study of 60 patients.

Tonsillectomy is regarded as a safe procedure, with post-operative taste disturbances rarely reported. The aim of this study was to access taste function after tonsillectomy in a series of 60 patients. Sixty patients (age range 14-40 years; mean 24.4 years; median 21 years; STD 7.7 years), 24 males and 36 females, underwent bilateral tonsillectomy at the University Hospital of Patras, Greece. All patients were diagnosed with recurrent tonsillitis and randomly assigned to two groups. The first group consisted of 27 patients, who underwent tonsillectomy using scissors and raspatory with electrocautery for coagulation. The remaining 33 patients underwent tonsillectomy using pressure-assisted tissue-welding technology. Chemogustometry was used to evaluate the patients' taste function on the first postoperative day and succeedingly, 15 days and 1 month postoperatively. Three different quantities of tastant were used in each test. Taste recognition in posterior tongue regions proved to be more affected compared with anterior tongue regions in the first postoperative day. Bitter and sour tastes were more affected than those of sweet and salty. Succeeding tests yielded near normal results for all patients except two, with one patient achieving normal taste function 1 month postoperatively and the other still facing taste disorders 1 month after tonsillectomy. The results indicate that Tonsillectomy entails a temporary reduction in taste function. This finding should be attributed to direct or indirect intraoperative damage of the glossopharyngeal nerve or unintentional extension of the lingual nerve by application of the tongue retractor. No significant difference was noted between the two operative techniques evaluated in our study. In most cases taste function returns to preoperative levels within 2 weeks postoperatively. Post-tonsillectomy taste disturbances are uncommon, and patients should be informed of this possibility.

[High exposure of the distal internal carotid artery]. / Der hohe Zugang zur Arteria carotis interna.

High exposure of the internal carotid artery is a challenging procedure even for experienced surgeons. Access to the distal internal carotid artery is impeded by progressive encroachment of the mastoid process and the angle of the mandible and furthermore at this level the artery is intimately associated with the hypoglossal and glossopharyngeal nerves. If high exposure is needed we prefer preparation of the distal internal carotid artery by dissection of the venter posterior of the digastric muscle and the styloid process including the stylohyoid and stylopharyngeus muscles. This procedure can be advantageously carried out without additional preoperative requirements. The need for high access to the internal carotid artery depends strongly on the underlying pathology: in atherosclerotic disease the rate of high access in our patients is approximately 4.4%, whereas in carotid aneurysms the rate is considerably higher and averages about 15%.

Glial vascular endothelial growth factor overexpression in rat brainstem under tolerable hypoxia: evidence for a central chemosensitivity.

The ventilatory response to hypoxia is mediated by peripheral inputs arising from the arterial chemoreceptors. In their absence, hypoxic adaptation can be achieved, possibly as a result of central cellular reorganization. To study this reorganization, we used chemodenervated rats to investigate the expression and localization of vascular endothelial growth factor (VEGF) in the brainstem. VEGF is a target gene of hypoxia-inducible factor (HIF) that is responsible for the morphofunctional remodeling induced by hypoxia. Intact and chemodenervated rats were subjected to normoxia or hypoxia for 6 hr (10% O(2) in N(2)). VEGF protein was quantified in micropunches of brainstem tissue. Only chemodenervated animals showed an increased VEGF expression in response to hypoxia, whereas, in normoxia, VEGF expression was not modified by chemodenervation. The same hypoxic condition was repeated for 8 days before immunocytochemical staining with anti-VEGF; antiglial fibrillary acidic protein (GFAP), a marker of astrocytes; and anti-rat endothelial cell antigen-1 (anti-RECA-1) that recognizes endothelial cells. Confocal analysis showed a cellular colocalization of GFAP and VEGF, indicating that VEGF was overexpressed predominantly in astrocytes. Increased RECA-1 immunolabeling indicated an enhanced angiogenesis in chemodenervated rats subjected to hypoxia. These results indicate that glial cells and the vascular network contribute to the brainstem remodeling. The peripheral chemodenervation reveals a central O(2) chemosensitivity involving a cascade of gene expression triggered by hypoxia, which in intact animals may act synergically with peripheral chemosensory inputs.

Transcervical resection of the styloid process in Eagle syndrome.

We conducted a retrospective study to determine the treatment outcomes of 6 patients who had either unilateral or bilateral elongated styloid processes and symptoms consistent with Eagle syndrome. Five of these patients had undergone transcervical resection of the styloid process, with relief of symptoms over the follow-up period (mean: 8 mo). Two of the 5 patients experienced a transient weakness in the marginal mandibular nerve, and both recovered completely. The transcervical surgical approach to resection in patients with elongated styloid processes and Eagle syndrome appears to be safe and effective, although the risk for transient marginal mandibular nerve weakness is notable.