SEARCH · PubMed Health
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
The hypoglossal nerve is frequently involved in head and neck afflictions as a result of its long course. Hypoglossal nerve paralysis, rarely occurs as the initial presenting symptom. Clinical situations, where the hypoglossal nerve paralysis was an early symptom, are discussed. The anatomy of the nerve from the brain stem to the tongue is elaborated upon.
The hypoglossal nerve has been used both entirely and in part to repair the facial nerve. Using the partial technique it may be difficult to obtain sufficient length and a free interposed graft is then required to extend the hypoglossal element. In six sheep the facial nerve was excised between its emergence from the stylomastoid foramen and its bifurcation in the parotid gland. The hypoglossal nerve was exposed and split longitudinally producing a limb which was reflected towards the distal stump of the facial nerve. This left a gap of 4-5 cm which was bridged with a freeze-thawed coaxially aligned skeletal muscle autograft. The sheep were examined at 8 months. Laser doppler blood-flow studies showed the blood-flow distal to the graft to be about 25% of that at an equivalent site on the normal side. Peak nerve conduction velocities were also reduced on the repaired side but stimulation of the proximal hypoglossal nerve was nevertheless capable of causing adequate contraction of both facial and tongue muscles. Histological comparison of the repaired facial nerves with equivalent sites on the normal side showed a reduction in mean axon and fibre diameters with normal myelin sheath thickness for the regenerated axon sizes. All of these features are to be expected in a regenerated nerve and are consistent with a good level of recovery of function.
Horseradish peroxidase (HRP) retrograde tracing techniques and morphometric analyses were performed to investigate synaptic remodeling associated with neuronal and glial changes in the dorsal motor nucleus of the vagus (DMV) of cats after vagal-hypoglossal nerve anastomosis (VHA). At 25 days postoperation (dpo), in the early target-reinnervation stage, there were 50% fewer presynaptic boutons containing round vesicles (R) or round and large dense-cored synaptic vesicles (R+D) contacting HRP-labeled DMV motoneurons. The loss of R boutons was maintained throughout the remaining postoperative intervals up to 500 dpo, whereas R+D boutons were further reduced at 123 dpo but were restored at 315 dpo, so that, by 500 dpo, 71.4% of them had gained access to the DMV motoneurons. Boutons containing pleomorphic synaptic vesicles (P) were completely disconnected from the DMV motoneurons at 25 dpo and did not reappear even in the long-term reinnervation stage. Loss and recovery of presynaptic boutons occurred in parallel with changes in astroglial ensheathment of the DMV motoneurons. It is suggested that synaptic remodeling associated with astroglial ensheathment in the DMV may be influenced by some retrogradely transported factors/signals derived from the newly acquired target organ, viz. tongue skeletal musculature. Our results further suggest that the observed changes in boutonal configurations may be attributable to modified functions of the DMV motoneurons induced by VHA.
This research concerns the modulation by lingual afferences of the reflex activity of frog XII nucleus. Some informations on the processes utilized to obtain this effect has been achieved by comparing the glossopharyngeal-hypoglossal reflex evoked bilaterally after excision of one hypoglossal nerve. The reflex response and electrotonic potential become more intense omolaterally to the section of XII at the IV-V day; However these effects disappear later (XII-XV day). These observations completely disagree with the presence of a large injury normally produced in the nucleus of XII by retrograde motoneuron degeneration. The reflex facilitation has been attributed therefore to the degeneration of the afferent component which is associated in the amphibia to the XII and exerts centrally a PAD effects.
OBJECTIVE: To study the microsurgical anatomy of the facial nerve (FN) trunk and provide some important morphometric data about facial-hypoglossal nerve anastomosis (FHA). METHODS: Bilateral microsurgical dissection was performed on the heads of 9 cadavers fixed with formalin with three different methods. In the first method, the posterior belly of the digastric muscle was used as a mark, and the FN trunk was identified on the medial side of this muscle. In the second method, dissection was initiated at the parotid gland, the FN trunk was identified at its entrance into the parotid gland. In the third method, the styloid process was identified and traced back to the stylomastoid foramen (SMF). The FN trunk was identified on its emergence from the SMF. In every dissection, the whole FN trunk was exposed; its diameter and depth at the the SMF and its length were measured; its relationship, with other structures was studied. RESULTS: The FN invariably emerged from the cranial base through the SMF. Its diameter upon its emergence from the foramen was 2.57 +/- 0.60 mm. The mean minimal distance of the FN trunk from the skin surface in this area was 22.62 +/- 2.88 mm. The length of the FN trunk was 15.71 +/- 1.97 mm. The distance between the bifurcation and the mastoidale was 18.20 +/- 4.41 mm. The distance between the bifurcation and the mandibular angle was 39.91 +/- 8.38 mm. The distance between the mastoidale and the SMF was 17.91 +/- 2.68 mm. The branches from the FN trunk proximal to its bifurcation were the posterior auricular nerve, the digastric muscle nerve and the stylohyoid muscle nerve. CONCLUSION: The third method to expose the FN trunk on its emergence from the SMF is safe and reliable. It is feasible to use only part of the hypoglossal nerve fibers for anastomosis with the FN trunk.
Previous studies have shown the existence of a sympathetic component in some cranial nerves including the hypoglossal nerve. In this study, the horseradish peroxidase (HRP) tract-tracing retrograde technique and experimental degeneration method were used to elucidate the possible neuroanatomical relationship between the superior cervical ganglion (SCG) and the hypoglossal nerve of hamsters. About 10% of the SCG principal neurons were HRP positive following the tracer application to the trunk of hypoglossal nerve. Most of the HRP-labelled neurons were multipolar and were randomly distributed in the ganglion. When HRP was injected into the medial branch of the hypoglossal nerve, some of the SCG neurons were labelled, but they were not detected when HRP was injected into the lateral branch. The present findings suggest that postganglionic sympathetic fibres from the SCG may travel along the hypoglossal nerve trunk via its medial branch to terminate in visceral targets such as the intralingual glands. By electron microscopy, the HRP reaction product was localised in the neuronal somata and numerous unmyelinated fibres in the SCG. In addition, HRP-labelled axon profiles considered to be the collateral branches of the principal neurons contained numerous clear round and a few dense core vesicles. Besides the above, some HRP-labelled small myelinated fibres, considered to be visceral afferents, were also present. Results of experimental degeneration following the severance of the hypoglossal nerve showed the presence of degenerating neuronal elements both in the hypoglossal nucleus and the SCG. This confirms that the hypoglossal nerve contains sympathetic component from the SCG which may be involved in regulation of the autonomic function of the tongue.
Hypoglossal nerve palsy following intubation is a rare complication that can be reversible depending on the extent of nerve damage. A 63-year-old male with a sigma carcinoma was repeatedly intubated orotracheally due to postoperative complications. After the fourth intubation, bilateral, complete hypoglossal nerve palsy with severe dysarthria and swallowing disability was observed. A percutaneous endoscopic gastrostomy tube was inserted for nutrition and to prevent aspiration. Cerebral MRI showed no pathological findings, particularly in the brainstem. Electromyographic studies revealed pathological spontaneous activity of both glossal muscles without any motor unit potential consistent with an axonal lesion of both hypoglossal nerves. Nevertheless, complete clinical and electromyographical recovery occurred within 7 months. The bilateral hypoglossal nerve palsy in our patient was probably due to mechanical alteration during intubation, leading to axonotmesis. Hypoglossal nerve palsy following intubation might have a favourable prognosis as long as continuity of the nerve sheath is maintained.
BACKGROUND: Injury to the hypoglossal nerve is a complication associated with transarticular C1-2 screw placement. This complication can be caused by a misdirected or too long screw. Little is known about the optimal screw length and its relationship to the hypoglossal nerve. METHODS: Twenty cervical spine specimens were used to study the optimal length of the transarticular C1-2 screw. Using the Magerl technique, a 3.0 mm drill bit was inserted into the C2 lateral mass, passing through the C1-2 facet joint and penetrating the upper portion of the ventral cortex of the lateral mass of the atlas. After drilling, the hole length was measured between the dorsal cortex of the C2 inferior articular process and the ventral cortex of the C1 lateral mass. In addition, six sagittal-sectioned cadavers were carefully dissected to observe the location of the hypoglossal nerve in the anterior aspect of the atlantoaxial region. RESULTS: The results of the measurements showed that the mean optimal screw path length for all specimens was 38.1 +/- 2.2 mm with a range of 34-43 mm. There was no significant difference between sexes in the screw path length (p 0.05). The hypoglossal nerve lies vertically in front of the lateral portion of the C1 lateral mass and the C1-2 facet joint. The area where the hypoglossal nerve lies is approximately 2-3 mm lateral to the middle of the anterior aspect of the C1 lateral mass. CONCLUSIONS: This study suggests that the mean optimal transarticular C1-2 screw length may be 38 mm; however, the determination of the accurate optimal C1-2 screw length should be made on an individual basis. Risk to the hypoglossal nerve can be eliminated if Magerl's technique is performed exactly.
The case histories of four patients who developed hemiatrophy of the tongue from 3 to9 years after a course of curative radiation therapy for carcinomas of the head and neck are presented. These patients subsequently followed for from 1 1/2 to 6 years withoutlocal recurrence of the tumor, distant metastasis, or involvement of other cranial nerves, indicative of only a unilateral hypoglossal nerve atrophy. A review of the literatureshowed that peripheral and cranial nerve damages after radiation therapy have been reported for the optic nerve, hypoglossal nerve, oculomotor nerve, abducens nerve, recurrent laryngeal nerve, brachial plexus nerves and peripheral nerves of the extremeties. Reviewof clinical and experimental data indicated that in most cases, the damages were probably caused by extensive connective tissue fibrosis around and infiltrating the nerve trunks. Three possible types of peripheral and cranial nerve damages after radiation therapy are identified.
Following hypoglossal nerve transection, the microglia of the rat hypoglossal nucleus expressed protein kinase CK2 beta subunit immunoreactivity. CK2 beta immunostaining occurred on the operated side from postoperative day 3; on day 5 we observed strong immunoreactivity and the immunopositive microglial cell processes surrounded the injured neurones. Thereafter, the immunoreactivity decreased gradually and on day 10 the immunopositive cells surrounded only a few injured neurones. Electron microscopic observations on the hypoglossal nucleus revealed microglia-neuronal contact within 3 hours of nerve injury, and by day 3 all the injured neurones were in contact with microglial cells. These observations indicated that microglia-neuronal contact occurred earlier than the CK2 beta subunit immunoreactivity. CK2 may not be implicated during the initial migration of the microglia to the injured neurones; however, it may enhance the growth and elongation of the microglial cell processes around the injured neurones.
Hypoglossal nerve stimulation was investigated as a method to relieve an induced upper airway obstruction. Six dogs were implanted with a cuff electrode applied to each hypoglossal nerve and a pulse generator. After 4 weeks, the hypoglossal nerve was stimulated (50% duty cycle) for up to 8 weeks. At 12 weeks a double tracheotomy was placed, with a negative pressure intermittently applied to the upper limb, simulating inspiratory airway pressure. Unilateral hypoglossal nerve stimulation improved peak upper airway flow from an average of 0.1 L/s to 1.6 L/s (P = 0.0001). Seventy-seven percent of the maximum possible flow (explanted tracheotomy tube) was obtained with unilateral stimulation. Histopathological evaluation revealed no nerve damage secondary to chronic stimulation. This study provides support for clinical trials of hypoglossal stimulation for obstructive sleep apnea.
Hypoglossal nerve (cranial nerve XII) palsy is uncommon. Damage to this nerve produces characteristic clinical manifestations, of which unilateral atrophy of the tongue musculature is the most important. When these features are recognized, the radiologist, armed with knowledge of the normal anatomy of the area, can focus on each segment of the nerve in search of a cause. The hypoglossal nerve is divided into five segments: the medullary, cisternal, skull base, nasopharyngeal/oropharyngeal carotid space, and sublingual segments. Because each segment is usually affected by different disorders, localizing a lesion to a particular segment allows the radiologist to narrow the differential diagnosis. In this way, the most efficient imaging strategy for evaluation of the symptoms can be developed. Both computed tomography and magnetic resonance imaging are useful in assessing dysfunction of the hypoglossal nerve; the choice depends on the status of the patient and the preference of the radiologist.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Neurinomas of the hypoglossal nerve are rarely reported. In most cases these tumors are intracranial or sited at the skull base. Only a few solitary neurinomas of the twelfth cranial nerve have been reported. In most of these cases the tumors arose from the descending part of the nerve in the parapharyngeal space. We report the first neurinoma recorded arising from the submandibular course of the hypoglossal nerve.
BACKGROUND: Hypoglossal nerve stimulation has been demonstrated to relieve upper airway obstruction acutely, but its effect on obstructive sleep apnea is not known. OBJECTIVE: To determine the response in obstructive sleep apnea to electrical stimulation of the hypoglossal nerve. METHODS: Eight patients with obstructive sleep apnea were implanted with a device that stimulated the hypoglossal nerve unilaterally during inspiration. Sleep and breathing patterns were examined at baseline before implantation and after implantation at 1, 3, and 6 months and last follow-up. RESULTS: Unilateral hypoglossal nerve stimulation decreased the severity of obstructive sleep apnea throughout the entire study period. Specifically, stimulation significantly reduced the mean apnea-hypopnea indices in non-rapid eye movement (mean +/- SD episodes per hour, 52.0 +/- 20.4 for baseline nights and 22.6 +/- 12.1 for stimulation nights; P<.001) and rapid eye movement (48.2 +/- 30.5 and 16.6 +/- 17.1, respectively; P<.001) sleep and reduced the severity of oxyhemoglobin desaturations. With improvement in sleep apnea, a trend toward deeper stages of non-rapid eye movement sleep was observed. Moreover, all patients tolerated long-term stimulation at night and did not experience any adverse effects from stimulation. Even after completing the study protocol, the 3 patients who remained free from stimulator malfunction continued to use this device as primary treatment. CONCLUSION: The findings demonstrate the feasibility and therapeutic potential for hypoglossal nerve stimulation in obstructive sleep apnea.
An anomalous nerve supply from the hypoglossal nerve (XII) to the sternocleidomastoid muscle (SM) was observed in the right neck of an 82-year-old Japanese female. This nerve branch arose from the hypoglossal nerve at the origin of the superior root of the ansa cervicalis. The nerve fiber analysis revealed that this branch consisted of fibers from the hypoglossal nerve, the first and the second cervical nerves and had the same component as the superior root of the ansa cervicalis. SM appeared quite normal and the most part was innervated by the accessory nerve and a branch from the cervical plexus. The anomalous branch from XII supplied the small deep area near the anterior margin of the middle of the sternomastoid portion of SM. It is reasonable to think that the small deep area of SM, which was innervated by the anomalous branch from XII, occurs as the result of fusion of the muscular component from infrahyoid muscles. If the muscular component does not fuse with SM, it is thought to appear as an aberrant muscle such as the superior sternoclavicular muscle (Hyrtl) which is also supplied from a branch of the superior root of the ansa cervicalis.
Japanese familial amyloid polyneuropathy (FAP type I) is characterized clinically by autonomic and sensorimotor polyneuropathy. Bulbar palsy or lower cranial amyloid neuropathy has not been reported in this disease. We report a 72-year-old man with senile onset FAP type I, who developed bulbar palsy and sensorimotor polyneuropathy without autonomic failures. He noticed dysesthesia and muscle weakness in the feet at the age of 67 years. Neurological examination showed bulbar signs and sensorimotor polyneuropathy, but not autonomic neuropathy. Electromyography showed denervation in the tongue and extremities. Sural nerve biopsy revealed a profound reduction of myelinated fibers. Neuropathological studies indicated axonal degeneration and transthyretin-amyloid deposits in the peripheral nerves and hypoglossal nerves or roots. DNA analysis demonstrated transthyretinMet30 mutation. We provide the novel possibility that bulbar palsy, due to amyloid neuropathy, can occur in FAP type I. Copyright Rapid Science Ltd