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At least 343 records · Page 19Linked to original sources
PubMed2003

Conduction velocity of the rabbit facial nerve: a noninvasive functional evaluation.

The aim of this study was to evaluate standardized conduction velocity data for uninjured facial nerve and facial nerve repaired with autologous graft nerves and synthetic materials. An evaluation was made measuring the preoperative differences in the facial nerve conduction velocities on either side, and ascertaining the existence of a positive correlation between facial nerve conduction velocity and the number of axons regenerated postoperatively. In 17 rabbits, bilateral facial nerve motor action potentials were recorded pre- and postoperatively. The stimulation surface electrodes were placed on the auricular pavilion (facial nerve trunk) and the recording surface electrodes were placed on the quadratus labii inferior muscle. The facial nerves were isolated, transected and separated 10 mm apart. The gap between the two nerve ends was repaired with autologous nerve grafts and PTFE-e (polytetrafluoroethylene) or collagen tubes. The mean of maximal conduction velocity of the facial nerve was 41.10 m/s. After 15 days no nerve conduction was evoked in the evaluated group. For the period of 2 and 4 months the mean conduction velocity was approximately 50% of the normal value in the subgroups assessed. A significant correlation was observed between the conduction velocity and the number of regenerated axons. Noninvasive functional evaluation with surface electrodes can be useful for stimulating and recording muscle action potentials and for assessing the functional state of the facial nerve.

Animals↗
PubMed2006

[Landmark of facial nerve in middle ear surgery].

OBJECTIVE: To re-evaluate landmarks for facial nerve in middle ear surgery through temporal bone dissection and facial nerve surgery. METHODS: Some relative landmarks were found through 44 facial nerves dissection in cadaver and 106 cases of facial nerve decompression surgery. RESULTS: (1) Landmarks for vertical segment of the facial nerve: the vertical line in combined point between posterior and middle 1/3 horizontal semicircular canal clews the posterior edge of facial nerve; the prolong line of superior radian of incus short process clues to the anterior edge of the facial nerve, the facial nerve and horizontal semicircular canal are almost in the same plane. (2) Landmarks for horizontal segment of the facial nerve: the facial nerve tracks forward inferior to short process of incus and anterior to horizontal semicircular canal carina in 30 angel. The facial nerve, locating posterior and superior to cochleariform process and parallel with it, forms the step of middle-superior tympanic cavity and tracks forward to geniculate ganglion. (3) location of geniculate ganglion: The same distance prolong line of stapes head to cochleariform process clues to geniculate ganglion. (4) Location of the chorda tympani nerve: chorda tympani nerve, leaving tympanic sulcus at 3 clock of bone canaline left ear and at 9 clock of bone canaline right ear, tracks forward along tympani sulcus and then cross between long process of incus and manubrium. It lies in the border of pars tensa and pars flaccid and is about 5 - 8 mm from the stylomastoid foramen to where the chorda tympani nerve leaves the facial nerve. There is no difference of facial nerve structure in temporal bone dissection and in surgery. CONCLUSIONS: The fixed landmarks of middle ear are the frame of reference of facial nerve, in which horizontal semicircular canal is most invariable; and the safety of surgery will be improved by the reference of the facial nerve.

Ear, Middle↗
PubMed2002

Apoptosis and expression of BCL-2 in facial motoneurons after facial nerve injury.

BACKGROUND: Apoptosis has been implicated in neuronal degeneration after optic and sciatic nerve injury. The mechanisms contributing to facial motoneuron death are poorly understood. This study investigated the mechanisms underlying facial motoneuronal death and the expression of BCL-2 in facial motoneurons after facial nerve injury. METHODS: Morphologic changes in the facial motoneurons were examined by light and transmission electron microscopy, and TdT-mediated dUTP-biotin nick end labeling (TUNEL) methods was used. Expression of BCL-2 was studied by immunohistochemistry and in situ hybridization after facial nerve injury. RESULTS: Cell shrinkage, condensed cytoplasm, and apoptotic bodies were demonstrated in numerous cells under light microscopy. The chromatin was condensed and localized to the nuclear envelope, forming a crescent or cap, and the endoplasmic reticulum was still visible but appeared swollen under electron microscopy. In vivo TUNEL staining displayed positive facial motoneurons 7 days after facial nerve transsection. The BCL-2 expression in facial motoneurons declined and reached its lowest level on the fifteenth day (p < 0.05). The reduction in BCL-2 expression after facial nerve transsection close to the facial motoneuron nucleus was greater than that of facial nerve transsection far away from the facial motoneuron nucleus (p < 0.05). BCL-2 expression after crushing of the facial nerve was found to be more intense in comparison with that after nerve transsection at the stylomastoid foramen (p < 0.05). CONCLUSIONS: These findings indicated that motoneuron death induced by facial nerve transsection was consistent with the process of apoptosis. The endogenous BCL-2 in these motoneurons may protect facial motoneurons from axotomy-induced cell death.

Animals↗
PubMed1996

Cross-face facial nerve anastomosis: historical notes.

The anastomosis between the two facial nerves for the treatment of facial paralysis, in which the proximal stump of the severed facial nerve is not accessible, was utilized in eleven patients. The palsy was secondary to resection of an acoustic tumor in nine patients, sarcoma of the petrous bone was the cause in one and an automobile accident in the other. The original concept of anastomosing a branch of the normal pes anserinus to the trunk of the paralyzed facial nerve, as first presented by the author at the Second International Symposium on Facial Nerve Surgery held in Japan in September, 1970, has been modified. The technique of anastomosing the cervico-facial division of the normal facial nerve, and directing it to the temporo-facial division of the paralyzed facial nerve via a sural autograft 20-22 cm long, was combined with the utilization of the ipsilateral descendens cervicalis (hypoglossi). This nerve was anastomosed to the cervico-facial division of the paralyzed facial nerve and utilized in four patients. The technique is illustrated in detail.

Adolescent↗
PubMed1999

Exacerbation of facial motoneuron loss after facial nerve transection in severe combined immunodeficient (scid) mice.

The immune system functions to protect an organism against microbial infections and may be involved in the reparative response to nerve injury. The goal of this study was to determine whether the immune system plays a role in regulating motoneuron survival after a peripheral nerve injury. After a right facial nerve axotomy, facial motoneuron (FMN) survival in C.B-17 (+/+) wild-type mice was found to be 87 +/- 3.0% of the unaxotomized left side control. In contrast, facial nerve axotomy in C.B-17 (-/-) severe combined immunodeficient (scid) mice, lacking functional T and B lymphocytes, resulted in an average FMN survival of 55 +/- 3.5% relative to the unaxotomized left side control. This represented an approximately 40% decrease in FMN survival compared with wild-type controls. The reconstitution of scid mice with wild-type splenocytes containing T and B lymphocytes restored FMN survival in these mice to the level of the wild-type controls. These results suggest that immune cells associated with acquired immunity play a role in regulating motoneuron survival after a peripheral nerve injury.

Animals↗
PubMed1978

The course of facial nerve innervation for the levator veli palatini muscle.

The present study was designed to determine the motor nerve pathway of the facial nerve to the levator veli palatini muscle. The experiments were carried out on 10 anesthetized rhesus monkeys. Recorded and analyzed were evoked EMG responses of the levator veli palatini and the orbicularis oris muscles by electrical stimulation to both the facial nerve and its branch within the cranium. Muscle action potentials (M-waves) from the two muscles could be recognized on stimulating the facial nerve at the petrosal area of the temporal bone. On stimulating the greater petrosal nerve, M-waves from the levator muscle could be elicited. By cutting off the greater petrosal nerve at the middle cranial fossa, M-waves from the levator muscle completely disappeared on stimulating the facial nerve at the petrosal area. Results indicated that the course of the facial nerve for the levator veli palatini muscle is through the greater petrosal nerve.

Action Potentials↗
PubMed2002

Thixotropy of levator palpebrae as the cause of lagophthalmos after peripheral facial nerve palsy.

Patients with facial nerve palsy are at risk of developing corneal ulceration because of lagophthalmos (incomplete closure of the affected eyelid). Lagophthalmos could result from thixotropy of the levator palpebrae muscle--that is, the formation of tight crossbridges between the actin and myosin filaments of the muscle fibres causing stiffness of the muscle--rather than from paralysis of the orbicularis occuli muscle as previously supposed. This possibility was investigated in 13 patients with a peripheral facial nerve palsy in a prospective open study. The levator muscle of the affected eyelid was stretched by manipulation and downward movement of the passively closed upper eyelid for approximately 15 seconds. The amount of lagophthalmos was measured before and immediately after this manoeuvre. In all patients except one there was a clear reduction in lagophthalmos (mean reduction 72%; range 60-100%). Thus in this setting the lagophthalmos appears to be caused by thixotropy of the levator palpebrae muscle, which has implications for treatment.

Adolescent↗
PubMed2004

Facial nerve in parotidectomy: a topographical analysis.

OBJECTIVE: Establish normative data concerning parotidectomy and facial nerve dissection and determine the relationship between the length of the facial nerve dissected during parotidectomy and subsequent facial nerve paresis. STUDY DESIGN: Prospective mapping of facial nerve during parotidectomy and comparison with postoperative facial nerve function. METHODS: A prospective observational study of 78 patients who underwent 79 parotidectomy procedures. During each procedure, various topographical measurements were recorded. These measurements included the distance from the tragal pointer to the main trunk of the facial nerve, the distance to the pes anserinus, and length of each segmental branch dissected. In addition, a designation of the patient's tumor location was made by drawing a line from the ear canal to the nasal spine. Tumors above this line were designated anatomic zone A and those below the line were designated anatomic zone B. Finally, facial nerve function was quantified at a 1-week follow-up visit using the House-Brackmann Scale. RESULTS: The distance from the main trunk of the facial nerve to the tragal pointer was significantly (P < .000) less than the previously accepted standard of 1 cm. The cervical and marginal mandibular branches had more nerve dissected, whereas the eye and forehead branches were the least dissected. Results of an independent t test and logistic regression (P = .01, both) indicated that patients with temporary facial nerve paresis had a significantly greater amount of nerve dissected than patients without temporary facial nerve paresis. Patients with short-term facial nerve dysfunction had significantly (P < .01) more total nerve dissected (136.73 mm vs. 94.73 mm) than patients without short-term facial nerve dysfunction. Patients with nerve dissection lengths at the third quartile (130.0 mm) were 3.8 times more likely to experience temporary facial nerve paresis than patients with nerve dissection lengths at the first quartile (64.5 mm). CONCLUSIONS: The axiom that the main trunk of the facial nerve is located 1 cm from the tragal pointer may need to be modified to less than 1 cm. The cervical and marginal mandibular branches had more nerve dissected, whereas the eye and forehead branches were the least dissected. Facial nerve paresis after parotidectomy is associated with the length of the facial nerve dissected during the procedure. The greater the length of facial nerve dissected, the higher the chance of facial nerve paresis, albeit temporarily, in this particular series of patients.

Adolescent↗
PubMed1995

Compression of the facial nerve caused increased nitric oxide synthase activity in the facial motor nucleus.

Nitric oxide synthase activities in the facial motor nucleus were studied in rats after unilateral compression of the facial nerve. Using a radiometric assay which measured the total soluble nitric oxide synthase activities in the facial motor nucleus and the surrounding tissues, it was found that nitric oxide synthase activities were markedly increased during facial paralysis that resulted from compression of the facial nerve. The subsequent decrease in nitric oxide synthase activities between postoperative days 20 and 40 coincided with the recovery of facial functions. In contrast, staining with NADPH-diaphorase histochemistry revealed that the diaphorase activities in the facial motor neurons were markedly increased between days 20-40 when the total activities as measured biochemically were in decline. However, staining of the vascular endothelium was increased on postoperative day 7 when the total activity was high. It is suggested that the increase in total nitric oxide synthase activities immediately after facial nerve compression may be predominantly endothelial. Since the increase in neuronal NADPH-diaphorase reactivity coincided with the recovery of facial functions, increased neuronal nitric oxide synthase may be a contributing factor to the restoration of facial innervation. The results of this study show that biochemical measurements of soluble nitric oxide synthase activities in tissue homogenates and NADPH-diaphorase histochemical staining in tissue sections may represent two distinct populations of nitric oxide synthase.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Oxidoreductases↗
PubMed1992

Normal and abnormal pathfinding of facial nerve fibers in the chick embryo.

Development of the facial nerve was studied in normal chicken embryos and after surgical disruption of ingrowing sensory facial nerve fibers at 38-72 h of incubation. Disruption of facial nerve fibers by otocyst removal often induced a rostral deviation of the facial nerve and ganglion to the level of the trigeminal ganglion. Cell bodies of the geniculate ganglion trailed their deviating neurites and occupied an abnormal rostral position adjacent to the trigeminal ganglion. Deviating facial nerve fibers were labeled with the carbocyanine fluorescent tracer DiI in fixed tissue. Labeled fibers penetrated the cranium adjacent to the trigeminal ganglion, but they did not follow the trigeminal nerve fibers into the brain stem. Rather, after entering the cranium, they projected caudally to their usual site of entrance and proceeded towards their normal targets. This rostral deviation of the facial nerve was observed only after surgery at 48-72 h of incubation, but not in cases with early otocyst removal (38-48 h). A rostral deviation of the facial nerve was seen in cases with partial otocyst removal when the vestibular nerve was absent. The facial nerve followed its normal course when the vestibular nerve persisted. We conclude that disruption of the developing facial pathway altered the routes of navigating axons, but did not prevent pathfinding and innervation of the normal targets. Pathfinding abilities may not be restricted to pioneering axons of the facial nerve; later-developing facial nerve fibers also appeared to have positional information. Our findings are consistent with the hypothesis that navigating axons may respond to multiple guidance cues during development. These cues appear to differ as a function of position of the navigating axon.

Acetylcholinesterase↗
PubMed2004

Facial nerve injury induces facilitation of responses in both trigeminal and facial nuclei of rat.

A study was made of the effects of facial nerve transection on trigeminal stimulation- evoked field potentials in the principal trigeminal (Pr5) and facial nuclei (7) in rats. Although the transected branch of the facial nerve contains pure motoric efferents, it resulted in enhanced responses in both Pr5 and 7. These electrophysiological results suggest a functional circuitry involving the whiskers, trigeminal nerve, Pr5 and 7 and the facial nerve as efferent. The disconnection (opening) of this loop results in enhanced responsiveness of the neurons in both Pr5 and 7.

Action Potentials↗
PubMed1988

Intraoperative monitoring of the facial nerve.

Anatomic preservation of the facial nerve, with maximal facial function, is one of the goals of acoustic neuroma surgery. Application of electrophysiologic monitoring techniques is useful in achieving this goal. Preoperative electromyography and nerve conduction studies provide important prognostic information for preservation of the nerve and postoperative function. Intraoperative electromyography alerts the surgeon to facial nerve proximity and potential injury. Direct nerve stimulation is utilized to confirm the location and integrity of the nerve. Matched-pair analysis of two groups of patients demonstrated an increased ability to preserve the facial nerve with less postoperative facial deformity.

Adolescent↗
PubMed2006

Free vascularized lateral femoral cutaneous nerve graft with anterolateral thigh flap for reconstruction of facial nerve defects.

Wide resection of a malignant tumor in the parotid gland often results in loss of a long segment of facial nerve, as well as a soft-tissue defect. With conventional nerve grafts, functional recovery of the facial nerve is poor in cases with risk factors that might inhibit nerve regeneration, such as a history of irradiation and a recipient bed scarred from previous operations. For such cases, a vascularized nerve graft is reported to be more effective than a nonvascularized nerve graft. This paper describes the first successful use of a free vascularized lateral femoral cutaneous nerve graft combined with an anterolateral thigh flap to repair the facial nerve and a soft-tissue defect. This method is technically simple, has minimal donor-site morbidity, and typically results in successful nerve recovery.

Action Potentials↗