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At least 289 records · Page 16Linked to original sources

PubMed1992

Independent effect of various facial mimetic muscles on the nasolabial fold.

The independent effect of the contraction of various facial mimetic muscles on the nasolabial fold was defined through study of cadaver dissections. The four major lip elevator muscles were identified and the effect of traction of these muscles on the nasolabial fold was studied. This study identified the levator alae muscle (levator labii superioris alaeque nasi) as the primary facial muscle responsible for creating the medial nasolabial fold. The levator labii superioris muscle was found to define the middle nasolabial fold. These two facial muscles may be significant in the etiology of the prominent nasolabial fold that occurs with aging.

Aged↗

PubMed1999

Reflex excitability of facial motoneurons at onset of muscle reinnervation after facial nerve palsy.

We studied 18 patients with complete unilateral denervation of the facial muscles after idiopathic facial nerve palsy to determine whether motoneuronal excitability is enhanced in the few motor units that are active at onset of muscle reinnervation. The study was carried out between 75 and 90 days after the facial nerve lesion. We used two needle electrodes to record simultaneously the spontaneous and voluntary activity of the orbicularis oris (OOris) and orbicularis oculi (OOculi) muscles, as well as the responses to ipsilateral and contralateral facial and supraorbital nerve stimuli. All patients showed involuntary firing of motor unit action potentials (MUAPs) in at least one of the muscles. Synkinetic activation of motor units in the OOris was induced by spontaneous blinking in all patients, and by inhalation and swallowing in some. Electrical stimulation of the ipsilateral facial nerve induced a direct M response in only 4 patients. In contrast, long-latency reflex responses were induced in both muscles by electrical stimulation of ipsilateral and contralateral facial and supraorbital nerves in all patients, at latencies ranging between 44 and 132 ms. The shape of such MUAP reflex responses was the same as that of the MUAPs seen to fire at rest. These findings provide evidence of enhanced excitability of facial motoneurons in our patients. Such hyperexcitability may be partly responsible for the postparalytic motor dysfunction syndrome that occurs after facial palsy with severe axonal damage.

Action Potentials↗

PubMed1992

[Selective facial neurectomy for hemifacial spasm].

Twenty-six patients were treated for hemifacial spasm by selective facial neurectomy. The symptoms of hemifacial spasm can be relieved by performing extracranial selective facial neurectomy with preservation of the temporal and cervical ramus. The facial nerve branches have been identified by selective electrical stimulation over the nerve, which evokes responses from the corresponding facial muscles. Selective facial neurectomy were completed when stimulation of the nerve produces minimal movement in the orbicularis oculi muscle while normal contractions appear in the frontal region and lip portion. The results of surgery 2 years postoperatively indicated that the complete disappearance of hemifacial spasm was achieved in 65.6 percent of the patients. A slight relief was achieved in 15.5 percent of the patients. Unsatisfactory results were obtained in 11.5 percent. No spasm recurred in 7.5 percent of patients, but paralysis of frontal muscle persisted.

Adult↗

PubMed1995

Re-innervation of facial nerve territory using a composite hypoglossal nerve--muscle autograft--facial nerve bridge. An experimental model in sheep.

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.

Animals↗

PubMed2005

Neural network screening of electromyographic signals as the first phase to design novel human-computer interaction.

The present aim was to describe the first phase attempts to recognise voluntarily produced changes in electromyographic signals measured from two facial muscles. Thirty subjects voluntarily activated two facial muscles, corrugator supercilii and zygomaticus major. We designed a neural network based recognition system that screened out muscle activations from the electromyographic signals. When several subjects were tested according to the same test protocol, the neural network system was able to correctly recognise more than 95 % of all muscle activations. This is a promising result and we shall next proceed to modify the system for real-time functioning and then design its utilisation for various multimodal human-computer interaction techniques. The subsequent phase in the future will be the interaction backwards: when a computer program first recognised the use of the facial muscles, it will then follow the instructions given by the user. For instance, by using the facial muscles the subject could select or activate objects on the computer screen. This would be one of the opportunities that we develop to help, e.g., disabled persons, who are unable to use their hands.

Electromyography↗

PubMed1997

Biochemical changes in denervated muscle identified by magnetic resonance spectroscopy.

OBJECTIVE: Magnetic resonance spectroscopy (MRS) has the potential to noninvasively delineate early biochemical changes in denervated muscle. In this study, we examine metabolic changes in denervated rat facial muscles using quantitative invitro 1H and 31P MRS. METHODS: Forty male Wistar rats were subjected to transection of the facial nerve trunk on the left and sham exposure on the right, and allowed to recover. The animals were then reoperated at 1, 2, 4, or 8 weeks after the initial procedure. EMG of the facial muscles and facial nerve conduction studies were performed at both time points, and facial muscles were harvested from normal and control sides at the second procedure. Perchloric acid extracts of facial muscles were then prepared for analysis using MRS. RESULTS: The results showed a progressive time-dependent decrease in Cr, PCr, Pi, ATP, and ADP all on the transected side. CONCLUSION: This study is an important step in the development of clinically relevant noninvasive methods of assessing and quantifying degeneration in nerve-muscle systems.

Adenosine Diphosphate↗

PubMed2001

Dental and oral manifestations of sclerosteosis.

AIMS AND OBJECTIVES: Documentation of the oral and dental manifestations of Sclerosteosis. SETTING AND PARTICIPANTS: Sclerosteosis is a member of the family of genetic craniotubular hyperostoses. This severe progressive sclerosing bone dysplasia has important orofacial manifestations and a wide geographical distribution. Comprehensive oral and dental evaluation of eight affected adults in the Afrikaner community of South Africa was undertaken. RESULTS: Gross asymmetrical hypertrophy of the mandible was present in all eight patients, bilateral or unilateral facial paralysis with weakness of facial muscles due to facial nerve entrapment was present in six. Drooling of saliva and difficulties with mastication were frequent problems in these persons. The teeth were structurally and mechanically normal although there was partial anodontia in two patients and delayed eruption in another. Maxillary (palatal) and mandibular tori were present in every affected person. Due to the hyperostosis of the maxilla and mandible, tooth extraction was often a very difficult matter. There were no instances of post-extraction osteomyelitis of the mandible. CONCLUSIONS: Accurate differentiation of sclerosteosis from the other sclerosing bone dysplasias is crucial for effective dental prognostication and management.

Adult↗

PubMed1975

Familial paralysis of horizontal gaze. Associated with pendular nystagmus, progressive scoliosis, and facial contraction with myokymia.

Paralysis of horizontal gaze, pendular nystagmus, and progressive scoliosis were manifestations of an autosomal recessive genetic disease in four siblings. Bilateral facial myokymia with continuous facial contraction developed in the oldest patient. Electromyographic examination of his facial muscles after facial nerve block at the stylomastoid foramen showed absence of all muscle potentials, consistent with a supranuclear origin of the myokymia. Normality of convergence, vertical gaze, and pupillary constrictor reflex activity assured integrity of midbrain ocular motor function. Absence of horizontal vestibulo-ocular reflexes signified involvement of the pontine tegmentum in this distinctive heredofamilial syndrome.

Adolescent↗

PubMed1986

Electronic reanimation of facial paralysis--a feasibility study.

We set out to adapt the concept of functional electrical stimulation to the reanimation of the paralyzed face. In the New Zealand white rabbit model we studied the strength-duration curves of both innervated and denervated facial muscles. We next studied the electromyographic signals corresponding to different strengths of contraction of innervated facial muscles. With Teflon-coated stainless steel electrodes implanted at opposite ends of the denervated muscle groups under study, bipolar stimulation yielded useful mimetic function that was modifiable by varying the voltage output and the rate of pulse generation. We demonstrated that an electronic circuit can indeed respond to the voltage generated within a functioning facial muscle, and then reproducibly trigger a corresponding graphic signal in synchrony with the mimetic function. The next step will be to adapt an electronic circuit that will deliver a predetermined electrical current to a denervated facial muscle in response to a determined generated voltage in the contralateral corresponding innervated facial muscle.

Action Potentials↗

PubMed1999

Nonspecific facilitation of responses to transcranial magnetic stimulation.

We examined the effect of facial muscle contraction and eye movements on motor evoked potentials (MEPs) from the abductor pollicis brevis muscle (APB) evoked by transcranial magnetic stimulation (TMS). The hypothesis was that activity of large cortical regions (face) influences the excitability of spinal motoneurons via cortical or subcortical pathways. MEPs were recorded in 12 healthy subjects during the following conditions: (1) rest; (2) facial muscle contraction; (3) eye movements; (4) 10% precontraction of the target muscle; and (5) simultaneous target muscle precontraction and facial muscle contraction. In 9 subjects, spinal motoneuron excitability was assessed by measurements of F waves during the same facilitation maneuvers. Activation of eye and facial muscles clearly facilitated MEPs from the APB. The facilitation of MEP size during nonspecific maneuvers was almost similar to that obtained by target muscle precontraction, whereas shortening of latencies was significantly smaller. The occurrence and amplitude of F waves increased in parallel with MEP size during specific and nonspecific facilitation, pointing to spinal motoneuronal threshold changes as a potential facilitatory mechanism by facial and eye muscle activation. The different MEP latencies during specific and nonspecific facilitation were not explained by different spinal motoneuron excitability, but raise the possibility that supraspinal mechanisms contributed to nonspecific facilitation.

Adult↗

PubMed2005

Turns amplitude analysis of the orbicularis oculi and oris muscles.

OBJECTIVE: The aim of the study was to determine whether 'clouds' from turns amplitude analysis obtained from the orbicularis oculi and oris muscles without force monitoring can be used to differentiate pathological processes affecting the face. METHODS: The interference pattern from orbicularis oculi and orbicularis oris was studied using a concentric needle electrode. Data-points from 20 normal subjects were plotted on a logarithmic scale of mean amplitude between turns versus turns/second, from which linear regression analysis defined the 95% confidence intervals. This enabled us to draw the boundaries of the normal cloud on a linear plot. Data-points from the interference pattern in two pathological cohorts, of 6 patients receiving botulinum toxin injections (representing a neurogenic model), and 6 patients with a muscle dystrophy (representing a myopathic model) were plotted against the normal cloud. These findings were compared and correlated with the mean durations obtained on motor unit action potential analysis from these same two facial muscles. RESULTS: The majority of patients receiving botulinum toxin injections into their facial muscles showed a pattern of high amplitude with low turns/s, or low amplitude with a low-to-normal range of turns/s in both facial muscles. These findings were associated with high-duration motor unit action potentials in most cases. In the myopathic group of patients 66% showed a pattern of low amplitude with low-to-normal range of turns/s in O oculi and O oris. This correlated with short-duration motor unit action potentials in both facial muscles. CONCLUSIONS: We have demonstrated that turns amplitude analysis without force monitoring can be used to study the interference pattern from facial muscles and can be applied to differentiate primary neurogenic from myopathic pathological processes. SIGNIFICANCE: Turns amplitude analysis without force monitoring in the facial muscles can be used as an effective and practical method of interference pattern analysis to complement findings from conventional motor unit action potential analysis.

Action Potentials↗

PubMed2004

Cytoarchitecture and musculotopic organization of the facial motor nucleus in Cebus apella monkey.

The architecture and musculotopic organization of the facial motor nucleus in the Cebus apella monkey (a New World primate) were investigated using histological techniques and a multiple labelling strategy, in which horseradish peroxidase-conjugated neuroanatomical tracers (CTB-HRP and WGA-HRP) and fluorescent tracers were injected into individual facial muscles. The facial motor nucleus was formed by multipolar motoneurons and had an ovoid shape, with its rostrocaudal axis measuring on average 1875 micro m. We divided the nucleus into four different subnuclei: medial, intermediate, dorsal and lateral. Retrograde labelling patterns revealed that individual muscles were innervated by longitudinal functional columns of motoneurons. The columns of the orbicularis oculi, zygomaticus, orbicularis oris, auricularis superior, buccinator and platysma muscles were located in the dorsal, intermediate, lateral, medial, lateral and intermediate subnuclei, respectively. However, the motoneuron columns of the levator labii superioris alaeque nasi muscle and frontalis muscle could not be associated with a specific subnucleus. The present results confirm previous studies regarding the musculotopic organization of the facial motor nucleus. However, we observed some particularities in terms of the relative size of each column in C. apella, which might be related to the functional and behavioral importance of each muscle in the particular context of this primate.

Animals↗

PubMedDate not supplied

Pre- and postoperative facial nerve testing in patients with acoustic neuromas.

Clinical and electrophysiological examination of the facial nerve was performed in 49 consecutive patients, from December 1982 to January 1984, before and after surgical removal of acoustic neuroma. The electrophysiological examination included quantitative electromyography of the facial muscles and facial nerve stimulation with registration of amplitude and latency of evoked muscle potentials. 17 patients had tumours with an extrameatal size of 5-25 mm, 16 had tumours between 26 and 40 mm, and 16 (32%) tumours larger than 40 mm. At preoperative clinical examination, 9 patients had decreased facial motor function; 7 however, only by meticulous inspection, while 2 had a slight paresis. Two patients had hemifacial spasms. 25 patients had prolonged duration of motor unit potentials and/or increased incidence of polyphasic potentials by electromyography. Only one patient had denervation activity. Three patients had decreased amplitude of evoked muscle potentials to supramaximal stimulation of the facial nerve. Motor latency was normal. At the most recent examination between 3 and 12 months postoperatively, 65% of the patients had no or insignificant facial nerve involvement, 10% had slight and 25% significant involvement, of whom 6 had paralysis or only slight reinnervation. The preoperative clinical facial involvement and the degree of electrophysiological abnormality was poorly correlated to the motor function at the time of the most recent examination.

Adolescent↗

PubMed2005

The facial pattern of disgust, appetence, excited joy and relaxed joy: an improved facial EMG study.

The purpose of the study was to investigate the facial muscle pattern of disgust in comparison to appetence and joy, using an improved facial EMG method. We analyzed the activity of nine facial muscles in forty healthy subjects. The subject group was randomly divided into two groups (oversaturated vs. hungry) of ten women and ten men each. Four different emotions (disgust, appetence, excited-joy and relaxed-joy) were induced by showing pictures from the IAPS. Pre-visible facial muscle activity was measured with a new facial EMG. A Visual Analog Scale (VAS) was established. Disgust is represented by a specific facial muscle pattern involving M.corrugator and M.orbicularis oculi, clearly distinguishing it from the facial patterns of appetence and joy. The intensity of disgust is stronger in a state of hunger than under oversaturation and is altogether stronger in females than in males. Our findings indicate the possibility to explore the entire emotion system successfully through a state-of-the-art psychophysiological method like our EMG device.

Adult↗

PubMed2000

Transcranial magnetic stimulation in acute facial nerve injury.

OBJECTIVE/HYPOTHESIS: Available electrodiagnostic tests that are used to evaluate facial nerve injury examine the nerve distal to the stylomastoid foramen; because most facial nerve injuries are within the temporal bone, the tests cannot evaluate the nerve at or across the injury site. The interpretation of these tests depends on the predictability (or unpredictability) of distal degenerative process. Transcranial magnetic stimulation may be able to stimulate the nerve proximal to the injury site. The hypothesis of the present study is that in cases of mild traumatic facial nerve injury where axonal integrity is maintained, proximal stimulation of the nerve using higher than normal stimulus intensities to "overcome" the block at the injury site result in recordable facial nerve activity. STUDY DESIGN: A prospective controlled animal study comparing response to transcranial magnetic stimulation of the facial nerve in the following groups: mild injury, severe injury/transection, and control. METHODS: We studied 44 facial nerves in 22 cats. Fifteen nerves were subjected to mild trauma. Five nerves were severely crushed, 2 nerves were completely transected, and 22 nerves were not traumatized. All nerves were examined with the transcranial magnetic stimulation system before the trauma, immediately after the trauma, and at 3, 8, and 12 weeks after trauma. RESULTS: All nerves in the mild and severe trauma groups showed complete clinical paralysis immediately after trauma. The nerves in the mild trauma group showed significant increase in threshold as well as significant increase in latency for recordable facial muscle response to transcranial magnetic stimulation. Thresholds and latencies decreased gradually within 3 to 12 weeks and returned almost to preinjury levels. This paralleled the return of clinical facial muscle movement. In the severe trauma/transection group, the nerves had no facial muscle response to transcranial magnetic stimulation after trauma. Neither facial muscle response to transcranial magnetic stimulation nor facial muscle movements recovered. CONCLUSIONS: In cats transcranial magnetic stimulation can assess the integrity of the facial nerve after trauma and predict its potential for regeneration. This technique can excite the nerve proximal to the injury site and may play a role in the clinical evaluation of the acute traumatic facial nerve paralysis. It can be used immediately after trauma, because it does not depend on wallerian degeneration to occur.

Acute Disease↗

PubMed2005

Microsurgical repair of the facial nerve.

OBJECTIVE: To report a series of 18 patients who underwent microsurgical repair of the facial nerve using different techniques and to discuss the indications and results of facial reinnervation procedures. METHODS: Eighteen patients with post-surgical facial palsy underwent facial reinnervation using different techniques.'These included classic hypoglossal-facial anastomosis in 13 cases, one-stage hemihypoglossal-intratemporal facial nerve anastomosis and translabyrinthine removal of residual intra-canalar acoustic schwannoma in 3, hemihypoglossal-facial nerve anastomosis in one, and neurotization of facial muscles through a nerve graft in one. RESULTS: The facial muscle function improved in all patients, up to grade III in 7 cases (39 %), grade IV in 9 (50 %) and grade V in 2 (11 %). The tongue atrophy was minimal in 70.5 %, moderate in 17.5 % and severe in 12 %. The outcome was better in younger patients (less than 40 years of age) and in those with a lesser grade of preoperative facial impairment. CONCLUSIONS: The classic hypoglossal-facial anastomosis is the technique of choice in most cases. The use of the intratemporal facial nerve is indicated when removal of an intra-canalar residual schwannoma must also be performed. The neurotization of the facial muscles through a nerve graft may be used when there is no distal trunk of the facial nerve available for the anastomosis.

Adult↗

PubMed1996

Cosmetic denervation of the muscles of facial expression with botulinum toxin. A dose-response study.

BACKGROUND: Botulinum toxin has been used for facial hemispasm, strabismus, and blepharospasm. Recently it has been advocated to treat the frown lines. We have extended this program to treatment of other muscles of facial expression. METHODS: Botulinum toxin is injected into the muscles of facial expression in two or three sessions to produce a temporary loss of muscle tone. A standard method of cooling, injection, and compression was developed to minimize pain and bruising. OBJECTIVE: To complete a dose-response study to document the optimum timing and amount of toxin needed for each muscle group. RESULTS: Two to five Botulinum toxin units per muscle was as adequate as higher doses. Toxin that was reconstituted 30 days earlier produced the same loss of muscle tone as freshly mixed toxin. With two or three injection sessions loss of muscle tone lasted for up to 1 year. CONCLUSION: Botulinum toxin is highly effective as an adjuvant therapy for facial rejuvenation. This minor surgical procedure can temporarily reduce the lines on the upper face and produce a pleasing effect. With proper dosing and dilution this rejuvenation program becomes cost effective.

Adult↗

PubMed1988

Sonoanatomy of the muscles of facial expression.

Primary anatomic studies served for identification and differentiation of the individual mimetic muscles. As a second step, we investigated the clinical potential of ultrasound imaging to visualize the mimetic musculature in 15 volunteers. This examination technique was used to diagnose pathological alterations, especially associated with facial palsy. The excellent sonographic visualization of the mimetic musculature indicates that this technique may be a valuable adjunct in the diagnosis and differentiation of facial palsy, as well as in planning plastic surgery and reconstructive procedures, and in follow-up care.

Adolescent↗