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At least 19 recordsLinked to original sources
PubMed1998

Congenital partial absence of the facial muscles.

Facial asymmetry in a newborn infant suggests various diagnoses, including birth trauma and congenital hemifacial microsomia. But congenital absence or hypoplasia of facial muscles has not been known except for the depressor anguli oris muscle (DAOM). The authors' experience with surgical treatment of congenital hypoplasia of the risorius, zygomaticus major and minor, and levator labii superioris muscles is presented. Congenital facial muscle absence is uncommon. Although the hypoplasia of the DAOM is known, this disease is not fully clarified. The authors report a case of congenital partial palsy of the face in which some facial muscles were absent although the facial nerve was normal.

Adolescent↗
PubMed2001

Changes in a rat facial muscle after facial nerve injury and repair.

This study describes changes in a rat facial muscle innervated by the mandibular and buccal facial nerve branches 4 months after nerve injury and repair. The following groups were studied: (A) normal controls; (B) spontaneous reinnervation by collateral or terminal sprouting; (C) reinnervation after surgical repair of the mandibular branch; and (D) chronic denervation. The normal muscle contained 1200 exclusively fast fibers, mainly myosin heavy chain (MyHC) IIB fibers. In group B, fiber number and fiber type proportions were normal. In group C, fiber number was subnormal. Diameters and proportions of MyHC IIA and hybrid fibers were above normal. The proportion of MyHC IIB fibers was subnormal. Immediate and delayed repair gave similar results with respect to the parameters examined. Group D rats underwent severe atrophic and degenerative changes. Hybrid fibers prevailed. These data suggest that spontaneous regeneration of the rat facial nerve is superior to regeneration after surgical repair and that immediacy does not give better results than moderate delay with respect to surgical repair. Long delays are shown to be detrimental.

Adenosine Triphosphatases↗
PubMed2003

Preoperative facial muscle imaging predicts final facial function after facial nerve grafting.

BACKGROUND AND PURPOSE: Our goal was to determine whether preoperative MR imaging of facial muscles predicts facial function after facial nerve grafting. METHODS: A retrospective review of all patients undergoing facial nerve grafting between 1997 and 2001 revealed 26 patients. Twelve of the patients had adequate preoperative MR images available for review and had undergone clinical follow-up for at least 12 months. Eight had malignant parotid tumors, and four had benign skull base or parotid tumors. Preoperative facial muscle MR imaging appearance was categorized as symmetrical or asymmetrical. The asymmetrical images were further classified into mild or pronounced asymmetry. Preoperative facial function was classified by using the House-Brackmann scale. Postoperative function was graded with the May scale. RESULTS: Four patients had symmetrical facial muscles shown by preoperative MR imaging, three had mild asymmetry, and five had pronounced asymmetry. No or mild asymmetry had an 86% positive predictive value for good to excellent functional outcome. Eighty percent of patients with pronounced asymmetry experienced poor functional outcomes. Six of eight patients with malignant and perineural tumors at surgery had asymmetrical facial muscles revealed by preoperative MR imaging studies. CONCLUSION: Symmetrical or mildly asymmetrical facial muscles are predictive of good facial function after nerve grafting. Pronounced asymmetry of facial muscles on MR images is predictive of poor facial function after grafting. Asymmetric facial muscles on preoperative MR images are associated with perineural tumor spread in patients with malignant disease.

Adult↗
PubMed1984

Somatotopic representation of facial muscles within the facial nucleus of the mouse. A study using the retrograde horseradish peroxidase and cell degeneration techniques.

The somatotopic representation of facial muscles within the facial nucleus was investigated by means of the retrograde horseradish peroxidase and cell degeneration techniques in the mouse. The nasolabial muscle is represented in the dorsolateral, lateral, and dorsal intermediate subnucleus; the mentalis muscle, in the ventral intermediate subnucleus; the platysma, in the dorsomedial part of the dorsal intermediate subnucleus and along the lateral border of the dorsomedial and ventromedial subnucleus; the orbicularis oculi and frontalis muscle, in the dorsal portions of the dorsolateral, dorsal intermediate, and dorsomedial subnucleus; the rostral and caudal auricular muscles, in the dorsomedial and ventromedial subnucleus, respectively; and the caudal belly of the digastric muscle, in the suprafacial nucleus. The present study shows that the facial muscles are represented in an orderly fashion in seven subnuclei of the facial nucleus, as in other animal species.

Animals↗
PubMed2006

Morphological evaluation of the human facial muscles.

The facial muscles are composed of striated muscle fibers, as well as other skeletal muscles, and can produce more delicate and complex expressions. We studied 12 facial muscles of 10 Japanese cadavers (8 males and 2 females, average 74.7 years old) by histological techniques. We measured the cross-sectional area of the muscle belly (mm2), number of muscle fibers per mm2, total number of muscle fibers, and muscle fiber size (microm2). The depressor anguli oris m. was predominant for the cross-sectional area and the total number of muscle fibers than other facial muscles. For the muscle fiber size, muscles inserted to the angle of the mouth were larger than those inserted to the lip. The orbicularis oculi and orbicularis oris muscles were the smallest facial muscles. The muscle fiber sizes in the facial muscles were less than other skeletal muscles.

Aged↗
PubMed1999

Clinical and experimental studies of large amplitude action potential of the suffered facial muscles in intratemporal facial nerve paralysis.

OBJECTIVE: To testify the phenomenon that large amplitude action potential appears at the early stage of facial paralysis, and to search for the mechanism through clinical and experimental studies. PATIENTS (ANIMALS) AND METHODS: The action potentials of the orbicular ocular and oral muscles were recorded in 34 normal persons by electromyogram instruments. The normal range of amplitude percentage was found out according to the normal distribution. One hundred patients with facial paralysis were also studied. The action potentials of facial muscles were recorded in 17 guinea pigs before and after the facial nerve was compressed and the facial nerve was examined under electromicroscope before and after the compression. RESULTS: The amplitude percentage of the suffered side to the healthy side was more than 153 percent in 6 of the 100 patients. Large amplitude action potential occured in 35 per cent guinea pigs which were performed the experiment of facial nerve compression. Electromicroscopic examination revealed separation of the lammae of the facial nerve's myelin sheath in the guinea pigs which exhibited large amplitude action potential. CONCLUSION: The facial nerve exhibited a temporary over-excitability at the early stage of facial nerve injury in some patients and guinea pigs. If the injury was limited in the myelin sheath, the prognosis was relatively good.

Action Potentials↗
PubMed2004

Motoneurons innervating facial muscles after hypoglossal and hemihypoglossal-facial nerve anastomosis in rats.

Hypoglossal-facial nerve anastomosis (HFA) is the most popular surgical procedure to reinnervate facial muscles after injury of the facial nerve. Section of the hypoglossus causes paralysis and atrophy of the hemi-tongue. In the attempt to overcome this consequence, the hemihypoglossal-facial nerve anastomosis (HHFA) has been proposed and only a half of the main trunk of the hypoglossus is connected to the distal stump of the facial nerve. In the rat, we have studied experimentally the anatomical nuclear changes after HFA and HHFA with the aim of establishing the quantitative motoneuron innervation of facial muscles obtained with each one of the two operative options. Horseradish peroxidase (HRP) injected in both types of anastomosis labeled not only hypoglossal motoneurons, but also facial motoneurons. HFA appeared to offer a significant quantitative motoneuron innervation higher than HHFA and then a higher probable better functional recovery. Both HFA and HHFA performed immediately after section of the facial nerve in rats did not result in a phenomenon of motor hyperinnervation. In our experimental model, the proximal facial nerve stump was coagulated at the stylomastoid foramen to avoid regeneration. Then, the labeled motoneurons into the facial nucleus could really be the expression of axonal projections from facial motoneurons to the hypoglossus nerve and facial muscles. No labeled motoneurons were seen contralaterally as we observed previously after section and repair of several nerves.

Anastomosis, Surgical↗
PubMed1982

Enzyme histochemical and histographic data on normal human facial muscles.

Four human facial muscles, platysma, m. levator labii, zygomaticus major and orbicularis oris, obtained during head and neck surgery, revealed no qualitative differences from normal human limb muscles, but differences with regard to fiber type distribution and fiber size. Mean fiber diameters of each muscle studied were largely 50% of those encountered in normal human limb muscles. Histographic analysis revealed that type II fibers were more frequent than type I fibers but that type IIB fibers were extremely scarce in number. The myofiber diameter spectrum was also larger in facial than in limb muscles, as myofibers produced variability coefficients around 325. The frequent presence of intramuscular nerve twigs and motor endplates may provide the opportunity of studying pre- and postsynaptic pathology in future studies of denervated facial muscles.

Adolescent↗
PubMed1984

Morphology of denervated human facial muscles.

17 biopsies of denervated facial muscles, the zygomatic, the orbicularis oris and the levator labii muscles, showed atrophic myofibers in most cases. There was loss of fiber typability when applying the NADH, the MAG and the alkaline ATPase reactions. The acid ATPase preparations allowed differentiation of myofibers into type I and type II without subtypes. Contrary to normal facial muscles that are richly endowed with motor endplates, no neuromuscular junctions were observed in denervated muscle fibers except one example which might have been obtained by false sampling from the marginal area of denervation or might be the result of partial reinnervation due to sprouting axons from the neighborhood. There was no correlation between the degree of muscle fiber atrophy and the duration of the paralysis. However, fibrosis corresponded to length of denervation. The presence of highly atrophic muscle fibers even 36 years after denervation indicates that the final aim of facial nerve surgery, namely the reinnervation of denervated facial musculature may still be achievable. However, endomysial and perimysial fibrosis may have a considerable impact on the final outcome of such facial nerve surgery. Unsatisfactory correlation between morphological and clinical as well as electromyographical findings in denervated facial muscles requires individual morphological study of each biopsy to assess the probable outcome of reconstructive facial nerve surgery. It therefore appears reasonable even in long-standing facial paralysis, to biopsy denervated facial muscles before or during surgical reanastomosation of the facial nerve. This study provides hints that morphological examination of denervated facial muscles may supplement clinical, electrophysiological, and possibly biochemical diagnostic findings.

Adolescent↗
PubMed1987

The ultrastructure of normal and denervated human facial muscle.

The ultrastructure of normal human facial muscles from 25 nonparalytic and 17 paralytic patients revealed normal features in nondenervated human facial muscles, identical to the fine structure of other normal human and mammalian cross-striated muscle fibers. However, in denervated facial muscle, a broad spectrum of ultrastructural lesions had affected sarcomeres, abnormal inclusions, and organelles. A large variety of inclusion bodies, some of which have not been described, were also found. The spectrum of ultrastructural changes showed no dependence on the length of the denervation period. There were no inclusion bodies in all the normal facial muscle biopsies. To our knowledge, this study represents the first systematic electron microscopic investigation of normal and denervated human facial muscles.

Adolescent↗
PubMed2004

Preoperative appearance of facial muscles on magnetic resonance predicts final facial function after acoustic neuroma surgery.

OBJECTIVE: Several previous studies have shown that muscle appearance on magnetic resonance is a sensitive indicator of muscle denervation. Previous attempts at determining preoperative indicators of final facial function after acoustic neuroma removal has been mostly unsuccessful. The goal of this study was to determine if the appearance of the facial muscles on preoperative imaging is predictive of final facial function after surgical removal of vestibular schwannomas. STUDY DESIGN: We conducted a retrospective chart and magnetic resonance review. SETTING: This study was conducted at a tertiary referral center. PATIENTS: We included all patients who underwent vestibular schwannoma removal between January 1, 1997, and December 31, 2001, with available preoperative magnetic resonance images and a minimum of 12 months follow up. INTERVENTIONS: We used translabyrinthine, middle fossa, and suboccipital approaches for tumor removal. A neuroradiologist, blinded to preoperative or final facial function after tumor removal, retrospectively reviewed preoperative magnetic resonance images. MAIN OUTCOMES MEASURES: Facial muscles were evaluated on magnetic resonance and classified as symmetric or asymmetric. Facial function was graded using the House-Brackmann scale. Preoperative facial function was noted on the preoperative physical examination. Final function was determined at least 12 months postoperatively. RESULTS: A total of 247 patients underwent tumor removal during the study period. One hundred thirty-two patients had adequate preoperative magnetic resonance images. Patients with preoperative facial muscle asymmetry seen on preoperative magnetic resonance indicating muscle atrophy had significantly worse final facial function, regardless of tumor size. CONCLUSION: The preoperative appearance of facial muscles provides valuable insight into the physiology of the facial nerve in the presence of vestibular schwannomas. Patients with pre-operative facial muscle symmetry have significantly better facial function than those with atrophy.

Adolescent↗
PubMed2001

Neostriatal stimulation activates tongue-protruder muscle, but not tongue-retractor or facial muscles: an electrical and chemical microstimulation study in rats.

Whether electrical microstimulation of a rat's striatal jaw region (SJR) in fact induced tongue or facial muscle activity in addition to jaw muscle activity was tested. Microstimulation of SJR-evoked EMG activity in a jaw-opener (anterior digastricus) and tongue-protruder (genioglossus). No activity was evoked in jaw-closers (temporalis or masseter), tongue-retractor (hyoglossus) or in facial muscles. In addition, the EMG effect could still be induced after extensive ablation of the neocortex; it was reproduced by microinjection of 50 mM kainic acid into SJR. The effective sites were histologically localized to a small central striatal region adjoining the anterior commissure. These findings may be of considerable value in understanding the striatal mechanism of orolingual dyskinesia involving involuntary jaw and tongue movements.

Animals↗