Zygomatic Branches Research Articles

Hemifacial spasm: results of electrophysiologic recording during microvascular decompression operations.

Electrophysiologic recordings were made from patients with hemifacial spasm (HFS) during microvascular decompression (MVD) operations to see if spasm and synkinesis are caused by ephaptic transmission at the site of lesion (root entry zone [REZ] of the facial nerve). The response from the orbicularis oculi muscle to electrical stimulation of the marginal mandibular nerve had a 2.2-msec longer latency (average of 16 patients) than the sum of the conduction times of the parts of the facial nerve that would be involved if the response was the result of ephaptic transmission at the REZ of the seventh cranial nerve. Similar results were obtained when the zygomatic branch of the facial nerve was stimulated. These results indicate that the facial motonucleus is involved in HFS.

Pathophysiology of hemifacial spasm: I. Ephaptic transmission and ectopic excitation.

We studied 62 patients with hemifacial spasm to test the presence of ephaptic transmission and ectopic excitation. The zygomatic and mandibular branches of the facial nerve were stimulated separately, recording simultaneously from the orbicularis oculi and mental muscles. Antidromic impulses were transmitted bidirectionally between the two branches. Transmission took place in a fraction of slow conducting motor nerve fibers. After-activity and late-activity were recorded as single potentials or trains, suggesting autoexcitation of fibers. The interspike frequency was 250 to 350 Hz. Hyperventilation produced synchronous clonic-tonic activity, suggesting ectopic excitation caused by hypocalcemia. Ectopic excitation and ephaptic transmission are important pathophysiologic factors in hemifacial spasm.

Lesions of the facial and trigeminal nerve in leprosy: An evaluation of 43 cases

Facial and trigeminal nerve involvement was studied in 43 leprosy patients, 5.7% of the 750 Thai national in-patients of a leprosy rehabilitation centre. Involvement of the facial nerve occurred late in the disease and had an average duration of 12.1 years. The zygomatic branches of this nerve were the most frequently affected. Hypaesthesia and anaesthesia were most often observed in the maxillary divisions. Periorbital surgical procedures to prevent severe ocular complications are evaluated and discussed.

Facial reflexes evoked by electrical stimulation of peripheral facial nerve branches in the cat: Experiments of the auriculotemporal—Facial nerve anastomoses

A reflex action potential in the orbicularis oculi muscle, in addition to the direct M response, has been evoked by electrical stimulation of the zygomatic branch of the ipsilateral facial nerve in decerebrate cats. The afferent part of the reflex arc runs via the auriculotemporal-facial nerve anastomoses to the mandibular nerve. This reflex potential has a lower threshold than the M response. Its waveform and its relatively small latency fluctuation are suggestive of a monosynaptic reflex arc. However, the mechanically evoked orbicularis oculi stretch reflex has a much smaller latency and has its afferent pathway via direct trigeminal fibers. The M reflex and the reflex action potential were likewise evoked in the lip musculature by electrical stimulation of the upper and lower buccal branch of the ipsilateral facial nerve. The clinical aspects of this reflex are discussed.

A conditioned eyeblink obtained by using electrical stimulation of the facial nerve as the unconditioned stimulus

Cats acquired a conditioned eyeblink (CR) in a situation where the conditioned stimulus (CS) was a click and the unconditioned stimulus (US) was unilateral electrical stimulation of the zygomatic orbital branch of the facial nerve, which is a motor nerve. In a discriminative training program, cats received both a click paired with a nerve stimulation and an interspersed unpaired hiss delivered randomly; these cats developed a CR only to the click. No CR developed in cats trained with random presentation of both click and nerve stimulation. Of those cases in which a CR was present, as measured electromyographically, this CR was distinguishable from background noise unilaterally approximately 50% of the time and was bilaterally distinguishable the remainder of the time. This CR could be extinguished and easily relearned and was specific for blink musculature. Acquisition rates for the CR were somewhat, but not significantly, slower than rates for cats trained with glabella tap US. Cats with a trigeminal rhizotomy on the side used for facial stimulation developed A CR, indicating that inadvertent stimulation of trigeminal afferents cannot account for CR development. Experiments on cats with both Vth and VIIth nerves cut unilaterally indicated that other possible afferents were unlikely to be involved. Thus, the sensory excitation ordinarily produced by the US appears to be unnecessary in this case, and firing of facial motoneurons at a suitable interval after the click CS is a sufficient condition for development of this CR.

Mechanisms underlying reserpine-induced ptosis and blepharospasm: Evidence that reserpine decreases central sympathetic outflow in rats

Reserpine-induced blepharospasm in rats is a central action mediated through the temporal and zygomatic branches of the facial nerve. Reserpine-induced ptosis, on the other hand, occurs as a consequence of reduced sympathetic outflow. Evidence is presented that this reduction in sympathetic outflow occurs as a consequence of peripheral depletion of norepinephrine from postganglionic sympathetic nerve endings as well as via a central or preganglionic reduction in sympathetic outflow. The degree of central as opposed to peripheral effect is apparently dependent on pretreatment time as well as on the dose of reserpine administered.

A Case of Unilateral Mandibulo-Facial Dysostosis Associated with Complicated Malformation of the Ear

A case of a male child aged 6 years, who had an unilateral, incomplete mandibulo-facial dysostosis associated with rare deformities of the ear, was reported. There was no significant family history concerning the congenital abnormalities. He was born at full term after what appeared to have been an uneventfull pregnancy. It was considered as one of causal factors that the early rupture of the faetal membran had made his birth very difficulf. His mental and bodily development was assured to be normal by the pediatric examination. On the otological and radiographic examination, we found that he had very complicated and various deformities on the left side of the head, face and neck.Significant findings among these deformities are listed as follows.1. A fissure, having been operated several days after his birth, extending laterally from the left angle of the mouth.2. The grossly deformed left auricle, microcia, lop ear and auricular appendixes, displaced to caudo-ventrally at the angle of the lower jaw. There was an opening of soft external auditory meatus, covered with the deformed auricle, directed latero-cranially and ended at the ossal part.3. Although asymmetry of palpebllar fissure was recognized, there were no manifest eye signs relating to this syndrom.4. The atrophia of the left zygomatic arc and branch of the mandibule, as one of representative signs of dysostosis mandibulo-facialis, was marke also in this case.5. Paralysis of the left facial nerve caused by the lesion in the facial canal.6. On the radiographic examination of the left temporal bone, the poorly developed mastoid cells, antrum and tympanic cavity were recognized. Moreover, dislocation of the left pyramis, deformity of labyrinth capsule, and a large notch at the internal porus of the acoustic nerve, were demonstrated.7. About an average of 30db hearing loss of bone conduction of the left ear was revealed by audiometrtic examination. Audiogram of the right ear was almost normal pattern.Based on the radiographic findings of the left pyramis, we assumed the perceptive type hearing loss of the left ear to the conginital damage of the accoustic nerve.A reviw of literatures was done, and the geneses of these congenital abnormalities were discussed.

THE MAXILLARY NERVE IN THE CEBOIDEA

Summary. The relative proportions and distribution of the zygomatic and infraorbital branches of the maxillary nerve have been examined in twenty‐one New World Monkeys, representing eight genera. In the subfamilies Aotinae and Pitheciinae the infraorbital nerve is bigger than the zygomatic, and twigs of its lateral branch form a plexus with filaments of the facial nerve. In the Atelinae and Cebinae, the zygomatic nerve is the bigger and some of its fibres are fasciculated with those of the seventh nerve. This variation in relative proportions is not correlated with any gross anatomical differences with facial structures in these monkeys.

Maxillofacial injuries: Reconstructive surgery of the dehiscent parotid duct and dehiscent peripheral facial nerve

Maxillofacial injuries: Reconstructive surgery of the dehiscent parotid duct and dehiscent peripheral facial nerve