Hyoid bone tenderness as a clinical indicator of laryngeal pathology.

OBJECTIVES: Hyoid bone tenderness is an underemphasized clinical abnormality and is described as discomfort or pain on gentle palpation of the greater cornu. The primary outcome of this study is to assess if there is any association between hyoid tenderness and laryngeal pathology. STUDY DESIGN: This is a retrospective case-control study. METHODS: Ninety-four subjects were identified. These were divided into two groups, those with hyoid tenderness and those without hyoid tenderness. Presenting complaints and findings on nasal laryngoscopy were compared to identify any association between hyoid tenderness and laryngeal pathology. RESULTS: There were a total of 76 (80.9%) female and 18 (19.1%) male patients in the study. Analysis of presenting complaints showed that dysphonia (P < 0.001, odds ratio = 4.82) and neck pain (P = 0.015, odds ratio = 10.9) were significantly associated with hyoid tenderness, more with these symptoms had hyoid tenderness than expected by chance. Findings on nasal laryngoscopy showed a significant association between hyoid tenderness and vocal fold nodules (P < 0.001). Nasopharyngitis (P = 0.065) and tense anterior neck muscles (P = 0.056) were almost significantly associated with hyoid tenderness. CONCLUSION: Hyoid tenderness has previously been reported as an early sign in acute epiglottitis. These results indicate that hyoid bone tenderness may be a useful clinical indicator of various other laryngeal pathologies or dysfunctions.

Effortful swallowing training coupled with electrical stimulation leads to an increase in hyoid elevation during swallowing.

We tested the effects of surface electrical stimulation on hyoid elevation during swallowing in healthy volunteers. Sixteen people were recruited and randomly divided into two groups. Electrical stimulation was applied to the skin above the infrahyoid muscle in the experimental group. The stimulation current was adjusted until muscle contraction occurred and the hyoid bone became depressed. Participants were asked to swallow forcefully so as to elevate the hyolaryngeal complex when the stimulation began. The same experiment was performed in the control group except the intensity of stimulation was adjusted to just above the sensory threshold. The two groups received ten 20-min treatments over 2 weeks. We recorded the myoelectrical activity of the submental muscles and the amount of hyoid bone movement at three time points (pretreatment, immediately post-treatment, and 2 weeks after treatment). In the experimental group, the amount of y-axis hyoid bone excursion was increased immediately post-treatment, but this effect faded within 2 weeks following the treatment. Myoelectrical activity was not affected by either treatment regimen. We concluded that effortful swallowing coupled with electrical stimulation increases the degree of hyoid elevation in healthy volunteers. It needs to be evaluated for its long-term effectiveness in increasing the elevation of hyolaryngeal complex.

Neuropilin 1 and 2 control cranial gangliogenesis and axon guidance through neural crest cells.

Neuropilin (NRP) receptors and their class 3 semaphorin (SEMA3) ligands play well-established roles in axon guidance, with loss of NRP1, NRP2, SEMA3A or SEMA3F causing defasciculation and errors in growth cone guidance of peripherally projecting nerves. Here we report that loss of NRP1 or NRP2 also impairs sensory neuron positioning in the mouse head, and that this defect is a consequence of inappropriate cranial neural crest cell migration. Specifically, neural crest cells move into the normally crest-free territory between the trigeminal and hyoid neural crest streams and recruit sensory neurons from the otic placode; these ectopic neurons then extend axons between the trigeminal and facioacoustic ganglia. Moreover, we found that NRP1 and NRP2 cooperate to guide cranial neural crest cells and position sensory neurons; thus, in the absence of SEMA3/NRP signalling, the segmentation of the cranial nervous system is lost. We conclude that neuropilins play multiple roles in the sensory nervous system by directing cranial neural crest cells, positioning sensory neurons and organising their axonal projections.

Anatomic position of the lingual nerve in the mandibular third molar region as potential risk factors for nerve palsy.

Palsy of the lingual nerve (LN) during third molar extractions, ramus osteotomies, anesthetic injections, procedures of orthognathic, preprosthetic, and periodontal surgery are important complications reported with varying frequency. The purpose of this study is to present quantitative data describing the position and shape of the LN in the third molar area. In the course of dissection, the LN was noted, as well as the furcation pattern, position, course, and anatomic relations under 2.5X loupe magnification in 21 adult male human cadavers. The distance of the junction of the LN and the chorda tympani from the foramen ovale was measured as average 15.1 +/- 5.8mm. The 4 furcation patterns of the LN and the inferior alveolar nerve (IAN) were observed based on their relative positions. Bifurcation of them above the level of the mandibular notch (type I) was observed in 66.7% of the specimens. The horizontal distance of the LN from the lingual plate of the mandible was greater in this study than in previous studies. This study provided measurable objective criteria for the relationship of LN in the third molar region. The knowledge of the relationship between the LN and third molar region is useful for the surgeon in avoiding unexpected complications.

Lingual foramina on the mandibular midline revisited: a macroanatomical study.

The purpose of the present study was to determine the incidence, size, location, course, and content of the foramina and bony canals located on the lingual side of the mandibular midline. Fifty dry human mandibles were morphometrically analyzed by measuring the distances of these midline foramina from the mandibular base and the dimensions of these foramina and their bony canals. In addition, macro- and microanatomical dissection was performed on 12 intact cadaver mandibles. The macroanatomic midline foramina were classified into superior and inferior genial spinal foramina according to their vertical location with respect to the genial spines. This study showed that out of 50 dry mandibles, 49 (98%) had at least one midline lingual foramen; only one lacked a true midline foramen. Evaluation of the microanatomical dissections indicated a clear neurovascular bundle in both superior and inferior genial spinal foramina and canals. For the superior canal, the content was found to derive from the lingual artery and the lingual nerve. For the inferior canal, however, the arterial origin was submental and/or sublingual, while the innervation derived from a branch of the mylohyoid nerve. In conclusion, different kinds of lingual foramina have been identified according to their location. The superior and inferior genial spinal foramina have different neurovascular contents, determined by their anatomical location above or below the genial spines.

Effects of surface electrical stimulation both at rest and during swallowing in chronic pharyngeal Dysphagia.

We tested two hypotheses using surface electrical stimulation in chronic pharyngeal dysphagia: that stimulation (1) lowered the hyoid bone and/or larynx when applied at rest, and (2) increased aspiration, penetration, or pharyngeal pooling during swallowing. Bipolar surface electrodes were placed on the skin overlying the submandibular and laryngeal regions. Maximum tolerated levels of stimulation were applied while patients held their mouth closed at rest. Videofluoroscopic recordings were used to measure hyoid movements in the superior-inferior and anterior-posterior dimensions and the subglottic air column position while stimulation was on or off. Patients swallowed 5 ml liquid when stimulation was off, at low sensory stimulation levels, and at maximum tolerated levels (motor). Speech pathologists, blinded to condition, tallied the frequency of aspiration, penetration, pooling, and esophageal entry from videofluorographic recordings of swallows. Only significant (p = 0.0175) hyoid depression occurred during stimulation at rest. Aspiration and pooling were significantly reduced only with low sensory threshold levels of stimulation (p = 0.025) and not during maximum levels of surface electrical stimulation. Those patients who had reduced aspiration and penetration during swallowing with stimulation had greater hyoid depression during stimulation at rest (p = 0.006). Stimulation may have acted to resist patients' hyoid elevation during swallowing.

Accessory innervation of the mandible: identification and anesthesia options.

The nerves commonly associated with accessory innervation of the mandible are identified and alternative techniques to gain their anesthesia are recommended, based on sound anesthetic principles and the current understanding of nerve anatomy.

Clinical significance of supplementary innervation of the lower incisor teeth: a dissection study of the mylohyoid nerve.

In view of the relevance of the mylohyoid nerve to clinical difficulties in achieving deep analgesia of the lower incisors, a dissection study was undertaken. Dissection from twenty-six adult cadavers of both sexes were studied with the aid of a dissecting microscope. The following observations were made: (1) A supplementary branch of the mylohyoid nerve entered the mandible through accessory foramina in the lingual side of the mandibular symphysis in 50% of the cases. (2) It generally arose from the right side (76.9%) and entered the inferior retromental foramen (84.6%). (3) The mylohyoid nerve branch either ended directly in the incisor teeth and the gingiva or joined the ipsilateral or contralateral incisive nerve. In view of this information concerning the high incidence of possible involvement of the mylohyoid nerve in mandibular sensory innervation, it is advisable to block it whenever intervention in the lower incisors is indicated. Routine mylohyoid injection is recommended after mental nerve block. If the inferior alveolar nerve is chosen for anesthetic purposes, additional mylohyoid injection should be given only if pain persists. The mylohyoid injection should be given at the inferior retromental foramen on the median aspect of the inferior border of the mandible through extraoral approach.