Human laryngeal ganglia contain both sympathetic and parasympathetic cell types

The differences in the anatomy of the thoracolumbar and sacral autonomic outflow are quantitative

PURPOSE

We have re-evaluated the anatomical arguments that underlie the division of the spinal visceral outflow into sympathetic and parasympathetic divisions.

METHODOLOGY

Using a systematic literature search, we mapped the location of catecholaminergic neurons throughout the mammalian peripheral nervous system. Subsequently, a narrative method was employed to characterize segment-dependent differences in the location of preganglionic cell bodies and the composition of white and gray rami communicantes.

RESULTS AND CONCLUSION

One hundred seventy studies were included in the systematic review, providing information on 389 anatomical structures. Catecholaminergic nerve fibers are present in most spinal and all cranial nerves and ganglia, including those that are known for their parasympathetic function. Along the entire spinal autonomic outflow pathways, proximal and distal catecholaminergic cell bodies are common in the head, thoracic, and abdominal and pelvic region, which invalidates the "short-versus-long preganglionic neuron" argument. Contrary to the classically confined outflow levels T1-L2 and S2-S4, preganglionic neurons have been found in the resulting lumbar gap. Preganglionic cell bodies that are located in the intermediolateral zone of the thoracolumbar spinal cord gradually nest more ventrally within the ventral motor nuclei at the lumbar and sacral levels, and their fibers bypass the white ramus communicans and sympathetic trunk to emerge directly from the spinal roots. Bypassing the sympathetic trunk, therefore, is not exclusive for the sacral outflow. We conclude that the autonomic outflow displays a conserved architecture along the entire spinal axis, and that the perceived differences in the anatomy of the autonomic thoracolumbar and sacral outflow are quantitative.

Topohistology of the cranial nerves IX-XII at the cranial base and upper parapharyngeal space: A histological study using human fetuses

The topographical relationships among the lower cranial nerves, internal carotid artery (ICA), and internal jugular vein (IJV) in the upper parapharyngeal neurovascular bundle remain obscure. Thus, details of the anatomy were examined in human fetus histology. We observed the horizontal histological sections from 20 midterm (9-18 weeks) and 12 near-term (28-40 weeks) fetuses. At the external skull base, the glossopharyngeal nerve crosses the anterior aspect of the IJV to reach the medially located Hyrtl's fissure in the petrous temporal bone. The nerve crossed the anterior aspect of the ICA medially near or below the first cervical nerve root. Below the hypoglossal nerve canal, the accessory nerve crosses the anterior or posterior aspects of the IJV and moves laterally. During the half-spiral course, the hypoglossal nerve was tightly attached to the posterolateral-anterior aspects of the vagus nerve and surrounded by a common nerve sheath. The glossopharyngeal ganglia sometimes extended inferiorly to the level of the hypoglossal nerve canal but were absent along the inferior course. The inferior vagal ganglion rarely extends above the occipital condyle. The superior cervical sympathetic ganglion occasionally extends above the first cervical nerve root. The IJV (or ICA) descends to the lateral (or medial) margins of the parapharyngeal neurovascular bundle. The glossopharyngeal (or accessory) nerve crosses the ICA (or IJV) to exit the bundle at the base of the skull (or below the hypoglossal nerve canal). The glossopharyngeal and vagus inferior ganglia differ at each site.

Cortical basis for skilled vocalization

We examined the cortical control of a laryngeal muscle that is essential for vocalization in two monkey species that differ in their vocal motor skill. Our results suggest that enhancements in vocal skill are coupled to enlargements in the descending output from two premotor areas, ventral area 6 (area 6V) and the supplementary motor area (SMA). This result challenges the view that improvements in motor skills are due largely to changes in the output from the primary motor cortex.

Marmosets display remarkable vocal motor abilities. Macaques do not. What is it about the marmoset brain that enables its skill in the vocal domain? We examined the cortical control of a laryngeal muscle that is essential for vocalization in both species. We found that, in both monkeys, multiple premotor areas in the frontal lobe along with the primary motor cortex (M1) are major sources of disynaptic drive to laryngeal motoneurons. Two of the premotor areas, ventral area 6 (area 6V) and the supplementary motor area (SMA), are a substantially larger source of descending output in marmosets. We propose that the enhanced vocal motor skills of marmosets are due, in part, to the expansion of descending output from these premotor areas.

Hypoxia-inducible Factor 2α: A Key Player in Tumorigenesis and Metastasis of Pheochromocytoma and Paraganglioma?

Germline or somatic driver mutations linked to specific phenotypic features are identified in approximately 70% of all catecholamine-producing pheochromocytomas and paragangliomas (PPGLs). Mutations leading to stabilization of hypoxia-inducible factor 2α (HIF2α) and downstream pseudohypoxic signaling are associated with a higher risk of metastatic disease. Patients with metastatic PPGLs have a variable prognosis and treatment options are limited. In most patients with PPGLs, germline mutations lead to the stabilization of HIF2α. Mutations in HIF2α itself are associated with adrenal pheochromocytomas and/or extra-adrenal paragangliomas and about 30% of these patients develop metastatic disease; nevertheless, the frequency of these specific mutations is low (1.6-6.2%). Generally, mutations that lead to stabilization of HIF2α result in distinct catecholamine phenotype through blockade of glucocorticoid-mediated induction of phenylethanolamine N-methyltransferase, leading to the formation of tumors that lack epinephrine. HIF2α, among other factors, also contributes importantly to the initiation of a motile and invasive phenotype. Specifically, the expression of HIF2α supports a neuroendocrine-to-mesenchymal transition and the associated invasion-metastasis cascade, which includes the formation of pseudopodia to facilitate penetration into adjacent vasculature. The HIF2α-mediated expression of adhesion and extracellular matrix genes also promotes the establishment of PPGL cells in distant tissues. The involvement of HIF2α in tumorigenesis and in multiple steps of invasion-metastasis cascade underscores the therapeutic relevance of targeting HIF2α signaling pathways in PPGLs. However, due to emerging resistance to current HIF2α inhibitors that target HIF2α binding to specific partners, alternative HIF2α signaling pathways and downstream actions should also be considered for therapeutic intervention.

Intrinsic Laryngeal Muscle Response to a Public Speech Preparation Stressor: Personality and Autonomic Predictors

Purpose Laboratory stressors have been shown to impact the activity of the intrinsic laryngeal muscles (ILMs), which may be part of the final causal pathway in some stress-induced voice disorders. Previous research suggests that personality traits such as stress reaction might increase one's susceptibility to these problems. Also, the autonomic nervous system response is implicated in the pathogenesis of voice disorders putatively involving ILM hyperfunction. The purpose of this study was to investigate personality and autonomic nervous system predictors of ILM responses to stressor exposure. Method Thirty-seven physically and vocally healthy female adults completed a personality questionnaire and were subjected to a speech preparation task intended to induce stress. Fine wire electromyography of the ILMs was performed so that the activity of these muscles could be measured prior to and during the stressor. Participants' trait stress reaction was measured as a personality-based predictive variable, as was respiratory-corrected respiratory sinus arrhythmia, a putative measure of vagal outflow to the heart. Results The personality measure trait stress reaction uniquely predicted thyroarytenoid, trapezius, and tibialis activity, whereas respiratory sinus arrhythmia uniquely predicted the activity of all muscles studied. Differences were observed in the autonomic predictor variable as a function of whether or not effects of respiration were accounted for in the variable's calculation. Conclusions This study explores the potential mediating roles of personality and autonomic function in ILM activity during a stressor. Both variables have value in predicting ILM activity during stressor exposure.

Differential Diagnosis in Neuroendocrine Neoplasms of the Larynx

The differential diagnosis of neuroendocrine neoplasms of the larynx is broad and includes lesions of epithelial, mesenchymal, and neuroectodermal origin. These lesions have overlapping clinical and pathologic aspects and must be carefully considered in the differential diagnosis of laryngeal neoplasms. The prognosis and treatment are also different among these tumor types, which necessitates making these distinctions clinically. The current literature was reviewed to provide updated information regarding the epithelial-derived tumors, including carcinoid, atypical carcinoid, small cell neuroendocrine carcinomas, large cell neuroendocrine carcinoma, and squamous cell carcinoma with neuroendocrine component. These tumors are compared and contrasted with non-epithelial-derived tumors such as paraganglioma and nonmucosal tumors, such as medullary thyroid carcinoma. The morphologic and cytologic features are discussed, along with helpful immunohistochemical and ancillary investigations.

A ganglion cell cluster along the glossopharyngeal nerve near the human palatine tonsil

CONCLUSION

The lingual branches of the glossopharyngeal nerve were most likely to bring not only gustatory nerves to the postsulcal part of the tongue but also autonomic nerves to the small glands and vessels. Tonsillectomy may injure the ganglion or reduce its function due to scar formation after surgery.

OBJECTIVES

To determine the topographical anatomy of a suggested ganglion cluster along the lingual branches of the glossopharyngeal nerve and to identify the incidence.

METHODS

In the human pharynges of 12 donated cadavers, we studied the ganglia using routine procedures for paraffin-embedded histology and immunohistochemistry.

RESULTS

Near the palatine tonsil, the lingual branches of the glossopharyngeal nerve often contained ganglion cells (in 9 of 12 specimens). The ganglion cells, 20-40 µ in diameter, were sparsely distributed along a 0.5-3.0 mm length of the nerve course attached to the posterolateral aspect of the superior pharyngeal constrictor. Most of these cells were positive for neuronal nitric oxide synthase, while some were positive for tyrosine hydroxylase. Thus, the ganglion was composed of a mixed population of sympathetic and parasympathetic neurons.