Pre-Operative Embolisation of an Aberrant Pharyngeal Arterial Branch Arising From the Internal Carotid Artery and Contributing Significantly to the Supply of a Large Juvenile Nasopharyngeal Angiofibroma

Preoperative embolisation of juvenile nasopharyngeal angiofibromas (JNAs) is a well-established treatment that reduces intraoperative blood loss and improves surgical outcomes. While the bulk of arterial supply to the tumour is derived from the external carotid system, some degree of contribution from the internal carotid artery (ICA) is common. ICA branch embolisation in this setting has previously been avoided due to concerns over ischaemic neurological complications, possibly contributing to the increased intraoperative blood loss observed in patients with tumours with ICA supply. There is a marked paucity of reports of embolisation of ICA branches supplying JNA in the medical literature. We present a case of successful embolisation of an aberrant pharyngeal branch of the ascending pharyngeal artery arising from the proximal cervical ICA, which was making a significant contribution to tumour blood supply in a male adolescent with a very large JNA.

Nitric oxide modulates elicitation of reflex swallowing from the pharynx in rats

The pharynx is very important for elicitation of reflex swallowing. The region of the pharynx is innervated by the pharyngeal branch of the glossopharyngeal nerve (GPN-ph). Nitric oxide (NO) plays an important role in various physiological functions. The purpose of this study is to investigate the contribution of NO to reflex swallowing evoked by electrical stimulation of the GPN-ph. Swallowing was evoked in urethane-anesthetized rats by application of repetitive electrical stimulation (10- to 20-μA amplitude, 10- to 20-Hz frequency, 1.0-ms duration) to the central cut end of the GPN-ph or superior laryngeal nerve. Swallowing was identified by electromyographic activity of the mylohyoid muscle. Latency to the first swallow and the interval between swallows were measured. Intravenous administration of NG-nitro-l-arginine (l-NNA, 0.6 mg/kg), a nonselective inhibitor of NO synthase (NOS), extremely prolonged latency to the first swallow and the interval between swallows evoked by the GPN-ph. Intraperitoneal administration of 7-nitroindazole (5.0 mg/kg), a selective inhibitor of neuronal NOS, significantly prolonged latency to the first swallow and the interval between swallows evoked by the GPN-ph. Administration of l-arginine (an NO donor, 500 mg/kg) and sodium nitroprusside (an NO releaser, 0.6 mg/kg) restored the suppression of swallowing induced by the NOS inhibitor. Superior laryngeal nerve-evoked swallowing was suppressed by administration of a higher dose of l-NNA (6.0 mg/kg). Swallowing evoked by water stimulation of the pharynx was also suppressed by l-NNA (0.6 mg/kg). These results suggest that NO plays an important role in signal processing for initiation of reflex swallowing from the pharynx.

Upper airway muscle paralysis reduces reflex upper airway motor response to negative transmural pressure in rat

The reflex upper airway (UA) motor response to UA negative pressure (UANP) is attenuated by neuromuscular blockade. We hypothesized that this is due to a reduction in the sensitivity of laryngeal mechanoreceptors to changes in UA pressure. We examined the effect of neuromuscular blockade on hypoglossal motor responses to UANP and to asphyxia in 15 anesthetized, thoracotomized, artificially ventilated rats. The activity of laryngeal mechanoreceptors is influenced by contractions of laryngeal and tongue muscles, so we studied the effect of selective denervation of these muscle groups on the UA motor response to UANP and to asphyxia, recording from the pharyngeal branch of the glossopharyngeal nerve ( n = 11). We also examined the effect of tongue and laryngeal muscle denervation on superior laryngeal nerve (SLN) afferent activity at different airway transmural pressures ( n = 6). Neuromuscular blockade and denervation of laryngeal and tongue muscles significantly reduced baseline UA motor nerve activity ( P < 0.05), caused a small but significant attenuation of the motor response to asphyxia, and markedly attenuated the response to UANP. Motor denervation of tongue and laryngeal muscles significantly decreased SLN afferent activity and altered the response to UANP. We conclude that skeletal muscle relaxation reduces the reflex UA motor response to UANP, and this may be due to a reduction in the excitability of UA motor systems as well as a decrease of the response of SLN afferents to UANP.

Pharyngeal branch of the glossopharyngeal nerve plays a major role in reflex swallowing from the pharynx

Mechanical stimulation of the pharyngeal areas readily elicits reflex swallowing. However, it is much more difficult for electrical stimulation of the glossopharyngeal nerve (GPN) to evoke reflex swallowing than it is for stimulation of the superior laryngeal nerve (SLN) to do so. These paradoxical findings remain unexplained; hence, the main purpose of this study was to explain this contradiction by using a urethane-anesthetized rat. Mechanical stimulation easily elicited reflex swallowing from the pharynx. The posterior pillars, posterior pharyngeal wall, and the soft palate of the rat were extremely reflexogenic areas for swallowing. Sectioning the pharyngeal branch of the GPN (GPN-ph), however, eliminated the swallowing reflex from these areas. In contrast, sectioning the lingual branch of the GPN had no effect on the elicitation of swallowing. Electrical stimulation of the GPN-ph and SLN elicited sequentially occurring swallows. The relationship between stimulus frequency and the latency of swallowing for the GPN-ph was approximately the same as that for the SLN. These results indicate that the GPN-ph plays a major role in the initiation of reflex swallowing from the pharynx in rats.