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PubMed2002

[Effect of trigeminus nerve on facialis-denervated facial muscle atrophy].

In the present study we made out an animal model on rabbit whose trigeminus and facialis nerves were simultaneously or only the latter one was severed. The pathological changes in facial muscle atrophy under different nerve injuries were investigated. The degeneration of contractile proteins of upper lip muscle -- myosin and actin was observed. In addition, we also examined the ultrastructural changes in the muscle atrophy in the two above-mentioned nerve injury cases. We observed that the intact trigeminus nerve could delay and lighten the atrophy of facialis-denervated facial muscle and attenuate the degeneration of myosin and actin, as well as decrease the increment of collagen and maintain the ultrastructure of the thick and thin muscle filaments. These results may provide the possibility of improvement of clinical treatment for facial muscle palsy.

Animals↗

PubMed2006

Quantitative EMG of facial muscles in myasthenia patients with MuSK antibodies.

OBJECTIVE: Our aim was to study the pathophysiological process leading to facial muscle atrophy in 13 patients with MuSK antibody positive myasthenia gravis (MuSK-MG), and to compare with findings from 12 acetylcholine receptor antibody positive myasthenia patients (AChR-MG), selected because they suffered from the same degree of disease severity and required similar treatment. METHODS: Motor unit action potential (MUAP) and interference pattern analysis from orbicularis oculi (O oculi) and orbicularis oris (O oris) muscles were studied using a concentric needle electrode, and compared with findings in 20 normal subjects, 6 patients receiving botulinum toxin injections (representing a neurogenic model) and 6 patients with a muscle dystrophy (representing a myopathic model). The techniques and control data have been reported previously. RESULTS: The mean MUAP durations for O oculi and O oris were significantly reduced (p<0.001) in both MG cohorts when compared with healthy subjects, and were similar to those in the myopathic control group. They were significantly different from those obtained from the neurogenic control group (p<0.001 for both O oculi and O oris). The MUAP findings in O oculi occurred independently from neuromuscular blocking on single fibre EMG (SFEMG) in the same muscle. On turns amplitude analysis (TAA), 50% of MuSK-MG patients and 42% of AChR-MG patients had a pattern in O oculi which was similar to that in the myopathic control group, and 62% of MuSK-MG patients and 50% of AChR-MG patients had a pattern in O oris that was also similar to that in the myopathic control group. The TAA findings for O oculi and O oris in both MG cohorts were different from those obtained from the neurogenic control group. CONCLUSIONS: Facial muscle atrophy in MuSK-MG patients is not neurogenic and the pathophysiological changes are akin to a myopathic process. The selected AChR-MG patients also show evidence of a similar pathophysiological process in the facial muscles albeit to a lesser degree. SIGNIFICANCE: We propose that muscle atrophy in MuSK-MG is a myopathic process consisting of either muscle fibre shrinkage or loss of muscle fibres from motor units. The duration of disease and long-term steroid treatment may be further contributory factors.

Action Potentials↗

PubMed1983

Localization of motoneurons innervating deep and superficial facial muscles in the rat: a horseradish peroxidase and electrophysiologic study.

In the rat, distribution of the motoneurons supplying the deep facial muscles (DFM)--the posterior belly of the digastric (VP) and the stylohyoid (SH) muscles--and the superficial facial muscles (SFM) was studied using the horseradish peroxidase (HRP) method and the antidromic field-potential method. The HRP was injected individually into the VP or SH or applied directly to the central end of the facial nerve cut immediately before it enters the parotid gland. Electrical stimulation was administered to the common stem of the branches innervating the VP or SH and to the facial nerve trunk just before entering the parotid gland. Both VP and SH motoneurons were found not in the main but in the accessory facial nucleus, within which the VP motoneurons were more numerous and more dorsorostrally extended than were the SH motoneurons. Motoneurons supplying the SFM were confined within the main facial nucleus. Evidence was found that the distribution of antidromic field potentials evoked by stimulation at the above sites coincided with the distribution of motoneurons supplying either the DFM or SFM obtained from the HRP experiment. In the rat, the accessory and main facial nuclei can be considered to be the mass of motoneurons exclusively innervating the DFM and SFM, respectively.

Animals↗

PubMed1984

The facial nucleus of the rat: representation of facial muscles revealed by retrograde transport of horseradish peroxidase.

The representation of facial muscle groups in the facial nucleus of rat was examined by retrograde transport of HRP. Motoneurons supplying muscle groups are arranged in longitudinal columns. Those supplying nasolabial muscles are located in the lateral and ventral intermediate segments, posterior auricular muscles in a medial column, platysma in an intermediate column; the lower lip and ocular muscles are in the ventral and dorsal segments respectively of the intermediate column. The posterior belly of the digastric muscle is supplied by motoneurons extending from the dorsal aspect of the facial nucleus to the caudal pole of the trigeminal motor nucleus.

Animals↗

PubMed2002

Control of facial muscle development by MyoR and capsulin.

Members of the MyoD family of basic helix-loop-helix (bHLH) transcription factors control the formation of all skeletal muscles in vertebrates, but little is known of the molecules or mechanisms that confer unique identities to different types of skeletal muscles. MyoR and capsulin are related bHLH transcription factors expressed in specific facial muscle precursors. We show that specific facial muscles are missing in mice lacking both MyoR and capsulin, reflecting the absence of MyoD family gene expression and ablation of the corresponding myogenic lineages. These findings identify MyoR and capsulin as unique transcription factors for the development of specific head muscles.

Animals↗

PubMed1993

Attenuation of facial muscle spasticity with intramuscular phenol neurolysis.

Intramuscular phenol neurolysis is a well-known procedure used to decrease spasticity and improve function in patients who have failed to respond to more conservative forms of intervention. Traditionally, this approach has been limited to spasticity reduction in limb muscles, and its use in managing spasticity of the facial muscles has not been described in the literature. This case report describes a new and previously unreported application of intramuscular neurolysis for managing severe unrelenting facial muscle spasticity in a postanoxic encephalopathic patient. Prior to the procedure, hypertonicity in the orbicularis oris muscle was so profound that it limited speech and affected cosmetic, hygienic, and nutritional status. After intramuscular phenol neurolysis of the orbicularis oris muscle, the patient's level of functioning improved.

Eating↗

PubMed1996

Molecular cloning of the rat NADH:ubiquinone oxidoreductase subunit and its up-regulation in the facial muscle after denervation: detected by means of differential display.

The differential display method was applied to identify gene expression which is especially up-regulated in the rat denervated skeletal muscle. Total RNA from normal and denervated facial muscles was isolated, amplified by PCR using certain primers, and separated by electrophoresis on polyacrylamide gel. PCR products which were apparently higher in the operated than in the control side were cut out from the gel and subsequently sequenced. One of the cDNA fragments obtained in the present study showed about 80% identity in nucleotide sequence and about 84% identity in amino acid sequence to one of the NADH: ubiquinone oxidoreductase (complex I) subunits from the bovine heart mitochondria (813). Complex I, the first and largest enzyme of the mitochondrial respiratory chain, transfers electrons from NADH to ubiquinone-10 (UQ-10). B13 is a 13 kDa subunit; deficiency of which causes incomplete or incorrect assembly of a functional complex I, resulting in one of the types of human mitochondrial myopathy. Northern blot analysis and in situ hybridization histochemistry confirmed that rat B13 mRNA expression was up-regulated after denervation and was distributed throughout whole muscle cell body. These findings suggest that up-regulation of the rat B13 mRNA expression after denervation plays an important role in the effective electron transfer from NADH to UQ-10 in skeletal muscle cells, resulting in restriction of lipid peroxidation and biological tissue damage.

Amino Acid Sequence↗

PubMed2005

Monitoring of facial muscle motor evoked potentials during microvascular decompression for hemifacial spasm: evidence of changes in motor neuron excitability.

OBJECT: Hemifacial spasm (HFS) is thought to be due to a hyperactive facial motor nucleus consequent to chronic neurovascular contact. The lateral spread (LS) response is presumed to reflect changes in facial motor neuron excitability. Facial muscle motor evoked potentials (MEPs) use the same efferent pathway as LS, therefore the authors speculated that these potentials should reflect differences consistent with changes at the facial motor nucleus level. METHODS: Monitoring of LS and bilateral facial MEP was performed in 10 consecutive patients undergoing MVD for HFS. Ipsilateral facial MEPs were monitored in 17 patients undergoing MVD for trigeminal neuralgia (TN). Latency, amplitude, and duration of the MEPs were compared before and after MVD. Following MVD the duration of ipsilateral MEPs decreased from 17.6 +/- 1.2 to 7.6 +/- 0.7 msec and their amplitude decreased from 269.9 +/- 66.3 to 76.5 +/- 26.2 microV (p < or = 0.01). These changes were consequent to the abolition of LS in eight of 10 patients and an approximately 50% reduction in two patients. The relationship between the reduction in MEPs and changes in LS was significant (p < 0.01). Control facial muscle MEPs (nonspastic side in patients with HFS and in those with TN) did not change significantly during the MVD procedure. Spasms were alleviated in nine of 10 patients, and there was no indication of facial nerve damage intraoperatively or postoperatively. CONCLUSIONS: Facial muscle MEPs represent a novel tool for studying the neurophysiological mechanisms of HFS in particular and monitoring the facial nerve in general. Data in this study support the hypothesis that the development of HFS and its alleviation with MVD are related to changes in facial motor nucleus activity.

Case-Control Studies↗

PubMed1994

[Neurophysiological study of hemifacial spasm--F wave of the facial muscles].

We studied the F wave of the facial muscles on both the normal side and the spastic side in 14 patients with hemifacial spasm. The purpose of this study was to determine if the mechanism of hemifacials spasm originates in ephaptic transmission in the facial nerve at the site of vascular compression or in a hyperexcited facial motor nucleus. Larger amplitude, longer duration and shorter latency F waves in the peripheral nerves than in normals indicate anterior horn cell hyperexcitability. We found abnormal potentials exhibiting synkinesis (lateral spread), a typical electrophysiological finding in hemifacial spasm, in the facial nerve evoked electromyograms of the 14 patients, none of whom had experienced facial palsy or facial nerve block. Electrical stimulation was delivered transcutaneously to the most distal portion of the marginal mandibular branch of the facial nerve. Using surface electrodes the F waves were obtained over the mentalis muscle as the second response after the M wave. While the F waves were normal on the patients' normal side, on the spastic side, their duration was longer (mean duration about 1.9 times that of the normal side), their onset latency was slightly shorter, and their F/M amplitude latency was greater than on the normal side. After microvascular decompression, the facial spasm and abnormal F-wave findings resolved. Onset latency was not increased, and on the spastic side some patients displayed facial spasm clinically and electrophysiologically for one year after MVD. In other words, there was hardly any focal demyelination of the facial nerve, so it is possible that ephaptic transmission and ectopic excitation are the mechanism of HFS.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

Morphology of experimentally denervated and reinnervated rat facial muscle. I. Histochemical and histological findings.

The morphological changes in rat facial muscles were evaluated after permanent denervation and were compared with findings after immediate reinnervation. Thirty rats underwent transection of the left and right facial nerves immediately followed by hypoglossal-facial nerve anastomosis on the right side (muscular reinnervation) and removal of 8-10 mm of the facial plexus on the left side (permanent muscular denervation). Levator labii muscle samples of both sides were collected sequentially at 2, 6, 7, 10, 20, and 24 weeks after surgery and submitted to routine histological and enzyme histochemical staining procedures. In normal levator labii muscles a typical "chessboard" pattern was found, with type I fibers being smaller than type II fibers. These latter fibers also were more prevalent than the type I fibers. Among the type II fiber subtypes, the type IIB fibers were larger and more frequent. Two weeks after surgery, there were no differences between denervated facial muscles and those undergoing reinnervation. Both showed atrophic myofibers among normal-sized fibers and slight fibrosis. Those muscles denervated for more than 2 weeks displayed increasing fiber atrophy with frequent loss of typability, as well as proliferation of connective tissue and fat cells in perimysial and endomysial sites. After denervation for 20 weeks only a few atrophic fibers were found in wide areas of fibrosis and fat cells. Following nerve anastomosis the reinnervated levator labii muscle showed much less fiber atrophy. Regrowth to normal fiber diameters was found with only a few atrophic myofibers 10 weeks after anastomosis although a moderate fibrosis predominated at perimysial sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphatases↗

PubMed1987

The effect of changes in facial muscle tension on respiratory resistance.

The relationship between changes in facial electromyographic (EMG) levels and respiratory resistance was examined. Thirty adult males were assigned equally to 1 of 3 groups; a facial muscle tension increase group (EMG increase), a facial tension decrease group (EMG decrease), and a noncontingent group (EMG noncontingent). Biofeedback procedures, based on EMG recordings made form electrodes positioned over the frontalis muscles, were used to effect muscle tension changes. Individuals in the EMG increase group exhibited increases in facial tension, but individuals in the EMG decrease group failed to show muscle tension changes. Respiratory resistance increased in individuals in the EMG increase group but did not change in individuals in the EMG decrease group. Like the EMG decrease group subjects, EMG noncontingent group subjects changed neither in facial tension nor in respiratory resistance. The results provided some support for a hypothesis linking facial muscle tension and respiratory resistance.

Adolescent↗

PubMed2000

Reduced facial expression and social context in major depression: discrepancies between facial muscle activity and self-reported emotion.

The expression of emotion is determined by emotion and the presence and absence of others, i.e. social context. The present study examined social context differences in facial muscle activity and self-reported emotion of 11 major depressed and 11 non-depressed patients. Subjects were asked to imagine happy and sad situations with and without visualizing other people. Facial muscle activity over the brow and cheek region was reduced in depressed compared to non-depressed patients during happy and sad imagery whereas self-reported emotion showed no group differences. In both subject groups, happy imagery induced increased smiling and self-reported happiness whereas sad imagery induced increased frowning and self-reported sadness. Smiling and self-reported happiness were increased during happy-social compared to happy-solitary imagery in both groups. In contrast, frowning showed a lack of social context differences, although self-reported sadness was increased during sad-social vs. sad-solitary imagery in both groups. Reduced facial muscle activity in depression may indicate psychomotor retardation whereas the lack of social context differences in frowning may suggest social disengagement and an inhibition of sad facial expression in the presence of others.

Adult↗

PubMed1977

[Functional state of the suprasegmental structures of the brain in experimental secondary contracture of the facial muscles].

For the first time the model of secondary contractures of facial nerves was used to study by long-term sterotaxic implanted electrodes the state of the cortex, amygdal complex, reticular formation of the middle brain, reticular nuclei of the pons and nuclei of the facial nerves. The experiments were accomplished on 31 rabbits. The experiments confirmed a close functional connnection of the VII pair of cranial nerves with the limbico-reticular complex. In secondary contracture there were factors facilitating the influence of pons reticular structures on the deficient system the facial nerve--facial muscles. The achieved data are used to explain the origination of the main symptom of secondary contractures--a stable increase of the muscular tone.

Amygdala↗

PubMed2003

A surface EMG electrode for the simultaneous observation of multiple facial muscles.

With previous surface electromyography (sEMG) electrodes it has been difficult to combine small outer dimensions and secure skin attachment. We resolved this problem by developing a new skin attachment technique that yields firm electrode fixation without requiring an acrylic housing. Consequently, we could reduce the outer electrode dimensions to 4-mm diameter and only 1.5-mm thickness. In a bipolar montage, this electrode allows an inter-electrode distance of 8 mm. This improves measurement selectivity and, because of the small dimensions, makes possible the non-invasive observation of multiple facial muscles with a minimum of obstruction. Our new technique was tested on a group of 11 professional trumpeters. They were instructed to perform a series of muscle-specific facial poses and to play exercises on their instruments while EMG signals were recorded simultaneously from seven different perioral muscles. Although the skin attachment was subjected to high stress during trumpet playing, more than 98% of electrode placements yielded a secure mechanical and electrical connection. Muscle selectivity of the signals recorded during the facial poses was similar to that obtained in a previous investigation using intra-muscular fine-wire electrodes. Crosstalk in the perioral area was estimated to be lower than 25%. The availability of an unobstructive sEMG electrode for simultaneously observing multiple facial muscles opens up a wide range of applications (e.g. in speech research, psychophysiology and orthodontics).

Adult↗

PubMedDate not supplied

Facial muscle tension influences lung airway resistance; limb muscle tension does not.

In healthy adult subjects, operantly conditioned increases in facial (frontalis) muscle tension produce increased lung airway resistance, whereas conditioned facial muscle relaxation results in decreased airway resistance. Conditioned increases and decreases in limb (brachioradialis) tension do not affect airway resistance. The latter finding rules out general muscular events and mitigates against metabolic agents as explanations of the airway resistance changes associated with facial tension change and suggests that the facial muscles influence airway resistance through the operation of a neural reflex.

Adolescent↗

PubMed2005

Representation of facial muscles in human motor cortex.

Whether there is a projection from the primary motor cortex (M1) to upper facial muscles and how the facial M1 area is modulated by intracortical inhibitory and facilitatory circuits remains controversial. To assess these issues, we applied transcranial magnetic stimulation (TMS) to the M1 and recorded from resting and active contralateral (C-OOc) and ipsilateral orbicularis oculi (I-OOc), and contralateral (C-Tr) and ipsilateral triangularis (I-Tr) muscles in 12 volunteers. In five subjects, the effects of stimulating at different scalp positions were assessed. Paired TMS at interstimulus intervals (ISIs) of 2 ms were used to elicit short interval intracortical inhibition (SICI) and ISI of 10 ms for intracortical facilitation (ICF). Long interval intracortical inhibition (LICI) was evaluated at ISIs between 50 and 200 ms, both at rest and during muscle activation. The silent period (SP) was also determined. C-OOc and I-OOc responses were recorded in all subjects. The optimal position for eliciting C-OOc responses was lateral to the hand representation in all subjects and MEP amplitude markedly diminished when the coil was placed 2 cm away from the optimal position. For the I-OOc, responses were present in more scalp sites and the latency decreased with more anterior placement of the coil. C-Tr response was recorded in 10 out of 12 subjects and the I-Tr muscle showed either no response or low amplitude response, probably due to volume conduction. SICI and ICF were present in the C-OOc and C-Tr, but not in the I-OOc muscle. Muscle activation attenuated SICI and ICF. LICI at rest showed facilitation at 50 ms ISI in all muscles, but there was no significant inhibition at other ISIs. There was no significant inhibition or facilitation with the LICI protocol during muscle contraction. The SP was present in the C-OOc, C-Tr and I-OOc muscles and the mean durations ranged from 92 to 104 ms. These findings suggest that the I-OOc muscle response is probably related to the first component (R1) of the blink reflex. There is M1 projection to the contralateral upper and lower facial muscles in humans and the facial M1 area is susceptible to cortical inhibition and facilitation, similar to limb muscles.

Acoustic Stimulation↗

PubMed1976

A new method to achieve complete akinesia of the facial muscles of the eyelids.

Blocking the facial nerve by injecting anesthetic agent over the most posterior, most superior palpable aspect of the ramus of the mandible produces more reliably complete facial nerve akinesia than obtained by the standard techniques used to obtain facial akinesia. The position is posterior and inferior to the point chosen for the classical O'Brien block. This new technique is safe and no complications have been noted in over 10 years of use. It is highly recommended as a method of achieving total hemifacial akinesia for ophthalmic procedures.

Eyelids↗

PubMed1999

Investigating the contamination of electroencephalograms by facial muscle electromyographic activity using matching pursuit.

It has been widely recognized and previously reported that electrical fields from facial muscle electromyographic (EMG) activity can contaminate the electroencephalogram (EEG), even when closely spaced, bipolar electrode configurations are used (personal observations). We suspected that EEG signals evoked in response to pressure changes in the upper airway may include EMG contamination subsequent to muscle reflexes triggered by the stimuli. We evaluated the potential contamination of the background EEG by voluntary activation of a facial muscle by obtaining simultaneous recordings in human subjects of the EEG (from Cz-C4) and masseter muscle EMG (from a bipolar surface electrode pair) before (quiet) and after voluntary tensing (VTen). Matching pursuit analysis permitted identification of different time-frequency patterns for each signal during the quiet period because the EMG signal has mostly atoms above 30 Hz compared to the EEG signal. However, the EEG showed periods of low-frequency activity unmatched in the EMG TF pattern below 30 Hz. During the tensing, most of the atoms of both the EEG and EMG shifted to the higher frequency regions above 100 Hz, making the separation difficult. These results further suggest that the matching pursuit method may not separate the background EEG from phasic EMG signals, both of which are nonstationary in nature.

Artifacts↗