Quantitative ultrasonography of facial muscles in patients with chronic facial palsy

Introduction: In this study we introduce quantitative facial muscle ultrasound as a diagnostic tool for patients with chronic unilateral facial palsy. Methods: Muscle area, thickness, and echo intensity of 6 facial muscles (frontalis, orbicularis oculi, orbicularis oris, depressor anguli oris, depressor labii inferioris, and mentalis) and of 2 chewing muscles (temporalis and masseter, as controls) were measured in 20 patients with chronic facial palsy. Results: Aside from 1, all facial muscles were significantly smaller on the paralyzed side. With exception of frontalis and orbicularis oculi muscles, all other facial muscles showed significantly higher echo intensity on the affected side. Muscle size and echo intensity of the chewing muscles showed no side‐to‐side asymmetry. Conclusions: Quantitative ultrasound of facial muscles helps to better characterize their status in patients with chronic facial palsy in the phase of denervation and during regeneration. Muscle Nerve 50 : 358–365, 2014     

The role of facial nerve conduction studies and electromyography in predicting the outcome of Bell's palsy

Many electrophysiological tests have been used to determine prognosis and extent of recovery in Bell's palsy but the reliability and sensitivity of the different parameters used is still controversial. We performed bilateral percutaneous facial nerve conduction studies, and volitional needle electromyography on 23 patients within 10–14 days post onset of their Bell's palsy. The following parameters were assessed: denervation and recruitment of the frontalis and orbicularis oris muscles, latency of the compound muscle action potential (CMAP), and CMAP amplitude ratio. The patients were re-examined 6 months later and their recovery graded according to the House-Brackman classification. The CMAP amplitude ratio and the recruitment scores of the frontalis and orbicularis oris muscles were the only parameters to reliably predict outcome (p = 0.016, 0.007 and 0.036, respectively). All patients with a CMAP amplitude ratio above 10% had a complete recovery. Since Bell's palsy is probably caused by herpes simplex virus, the active disease process is completed within 10–14 days; therefore, facial nerve conduction studies and electromyography at that time are appropriate to predict prognosis.     

Prognostic value of minimal excitability of facial nerve in Bell's palsy.

Nerve excitability is useful for prognosis in Bell's palsy. Minimal excitability values (MEV) were obtained by stimulating the facial nerve and recording the effective current (mA) required to evoke a minimal visible contraction of frontalis, orbicularis oculi, orbicularis oris, and mentalis muscles respectively. Serial MEVs were performed on 100 patients with facial palsy, of whom 87 were followed for six months or to complete recovery; 61 patients were treated with steroids of whom 57 had good recovery. Serial MEVs were not only useful for prognosis, but also helpful in regulating the dosage of prednisone.     

Turns-amplitude analysis in normal and myopathic facial muscles

The purpose of this study was to assess turns/amplitude analysis (TAA) as an objective alternative to conventional qualitative electromyography (EMG) for detection of myopathy in facial muscles. Normal values of TAA parameters were calculated in the frontalis and mentalis muscles of 26 control subjects. We estimated the slope of the regression line of mean amplitude/turn values (MA) plotted against the number of turns/second (NT) and the resulting clouds. The 95% confidence limits of the cloud data were drawn as an ellipse. The sensitivity of TAA was determined from a group of 35 myopathic patients and specificity from a second group of 25 control subjects. Significant differences for every TAA parameter were found between frontalis and mentalis. Cumulative sensitivity and specificity of TAA for frontalis and mentalis were 74.6%, 56.5%, and 73.3%, 70.8%, respectively. With at least two of the aforementioned criteria abnormal, the sensitivity and specificity for frontalis and mentalis were 61.3%, 82.6%, and 56.7%, 100.0%, respectively.     

MUAP values of two facial muscles in normal subjects and comparison of two methods for data analysis

Introduction: This study aimed to obtain normal MUAP values in 2 facial muscles and to compare the results of different analysis methods. Methods: The frontalis muscle of 36 and the mentalis muscle of 28 normal subjects were examined, and mean and outlier values of all MUAP parameters were calculated with the automatic method. Next, manual editing of the recorded raw data provided new sets of values for comparison. Results: The frontalis muscle MUAPs have significantly shorter duration, smaller amplitude and a lower number of turns and phases compared with those of mentalis. Higher MUAP duration values in the frontalis were the only significant difference after the comparison of the different analysis methods. Conclusions: The set of normal values for frontalis and mentalis in this study could be useful in routine practice. Careful manual editing of the frontalis MUAPs is recommended for more accurate determination of their duration. Muscle Nerve 46: 346-350, 2012.     

Quantitative ultrasonography of facial muscles

Introduction: There is no standardized method for examination of facial muscles with ultrasound. The purpose of this study was to identify those facial muscles accessible for reliable identification and to provide reference data. Methods: In healthy subjects all facial muscles were screened for visibility, separation from adjacent muscles, and reliability of landmarks. Bilateral scans of reliable muscles were performed in 40 adult volunteers. Results: Six facial muscles were clearly demarcated with ultrasound. These were: frontalis, orbicularis oculi, orbicularis oris, depressor anguli oris, depressor labii inferioris, and mentalis muscles. Cross-sectional area and muscle thickness showed gender differences and were independently related to age for some muscles. A significant left–right side difference was only seen for the orbicularis oculi muscle in women. Conclusions: These data demonstrate the usefulness of ultrasonography to assess facial muscles and provide reference values that can be applied in the clinical setting. Muscle Nerve 47: 878–883, 2013     

Trigemino-facial reflex inhibitory responses in some lower facial muscles

The effects of electrical trigeminal stimulation on activated facial muscles were studied in 20 normal subjects in order to evaluate whether excitatory or inhibitory responses are present and to investigate whether the reflex organization is similar in all the facial muscles. No inhibition was observed in frontalis, orbicularis oculi, orbicularis oris, and mentalis muscles. By contrast, a clear suppression of electromyographic (EMG) activity (late silent period or SP2) was present in the levator labii superioris, depressor anguli oris, and depressor labii inferioris muscles, with a mean latency ranging from 41.8 to 50.2 ms, and a mean duration ranging from 27.5 to 40.9 ms. An early suppression of EMG activity (early silent period or SP1) was observed, with a latency of 16 to 20 ms and a duration of 10 ms, mainly in inferior perioral muscles. Our findings show a selective trigeminal inhibitory influence upon some specific lower facial muscles.     

Anti-MuSK-positive myasthenia gravis: neuromuscular transmission failure in facial and limb muscles

The presence of antibodies against muscle-specific receptor tyrosine kinase (MuSK) appears to define a subgroup of patients with myasthenia gravis (MG) characterized by weakness predominant in bulbar, facial and neck muscles compared with anti-acetylcholine receptor (AChR) antibody-positive MG. To investigate the patterns and severity of neuromuscular transmission failure in different muscles in MuSK-positive MG, we performed single fiber electromyography (SFEMG) in the facial (frontalis) and limb (extensor digitorum communis, EDC) muscles in three anti-Musk-positive patients, and compared results with those of 11 anti-AChR-positive patients. Only one of the three MuSK-positive patients had abnormal jitter in EDC, but all the three showed clearly increased jitter in the frontalis. By contrast, the AChR-positive patients showed similarly abnormal jitter for the two muscles. These results suggest that when the diagnosis of anti-MuSK-positive MG is suspected, SFEMG should be performed in most prominently affected muscles.     

Identification of possible cognizance parameters of "mimic disintegration" in schizophrenia using facial electromyography

The aim of this study was to identify signs of "mimic disintegration" in schizophrenics using a facial electromyographic (EMG) method. We compared a group of 20 unmedicated schizophrenics with a group of 20 healthy subjects, measuring the activity of three joy-relevant facial muscles (zygomaticus major, orbicularis oculi, levator labii superioris) and two nonjoy-relevant facial muscles (frontalis, corrugator supercilii) as control muscles during two consecutive presentations of an erotic slide from the International Affective Picture System. RESULT: Schizophrenics show significantly less activity of joy-relevant facial muscles and a lower smile frequency than healthy subjects. Two signs of mimic disintegration" could be identified: 1. undefined mimic reactions and 2. lack of mimic consistency. CONCLUSION: Facial EMG is a state-of-the-art method for analyzing possible signs of mimic disintegration as described by Heimann and Spoerri. We suggest further examination of the two mimic disintegration signs regarding other emotions, necessarily including more facial muscles in the testing.     

A new method for measuring compound muscle action potentials in facial palsy: a preliminary study

To establish a simple, reproducible procedure for studying facial motor nerve conduction (MNC), we determined the optimal electrode position to record evoked compound muscle action potentials (CMAPs) from perioral muscles in normal subjects. We examined three new electrode positions in which the electrode connected to the one input of the amplifier was placed on the mental protuberance, and the one connected to the other input was placed on the skin over the orbicularis oris muscle (the philtrum, mouth angle, or lower lip). We then compared the morphology and amplitudes of the CMAPs, right-left differences, and the reproducibility of CMAP amplitudes with recordings taken from the standard electrode position in which one electrode was placed on the nasolabial fold closely lateral to the ala nasi, and the other was placed on the skin over the orbicularis oris. Percutaneous supramaximal electrical stimulation was applied to the main trunk of the facial nerve. All three of the new recording positions showed greater amplitudes and more obvious biphasic CMAPs than the standard method. Positioning the electrode connected to the negative input on the philtrum was optimal in terms of right-left differences and the reproducibility of CMAP amplitudes. Therefore, this midline recording is a simple, reproducible method for calculating the CMAP amplitude ratio. However, prior to clinical use of this procedure, analyses of patients with facial palsy are required.     

Motor unit number estimation in facial paralysis

The value of motor unit number estimation (MUNE) in determining the prognosis of acute peripheral facial paralysis (PFP) was evaluated in 89 patients with PFP on days 6, 8, 11, 14, 20, and 30 of PFP and repeated once per month until complete recovery or the end of the first year. The symptomatic/asymptomatic side ratios of the compound muscle action potential (CMAP) amplitudes recorded from nasalis muscles and MUNEs studied using the incremental method by recording from the same muscle were assessed with regard to three outcome groups (Group I, complete recovery; Group II, mild dysfunction; Group III, moderate-moderately severe dysfunction). CMAP and MUNE ratios were parallel to each other in all patient groups throughout the observation period with lower values in the more severe groups. However, CMAP amplitude loss was significantly greater than the MUNE loss in the first 3 weeks of PFP. The MUNE method is not superior to CMAP size in determining prognosis in PFP. However, the significant disparity between the CMAP and MUNE ratios in the early period may have some physiological relevance with regard to the pathophysiology of the Wallerian degeneration process and deserves further research into its potential sources.     

Blink reflexes and lateral spreading in patients with synkinesia after Bell's palsy and in hemifacial spasm

We compared various electrodiagnostical tests in patients with hemifacial spasm and in patients who developed synkinesia after Bell's palsy. We examined the evoked blink reflexes in the orbicularis oculi (o. oculi) and orbicularis oris (o. oris) muscles in 23 patients with hemifacial spasm (HFS), in 10 patients with synkinesia after Bell's palsy (BPS) and in 22 control subjects. In the patient groups, we recorded synkinesia, latency and amplitude of compound muscle action potential (CMAP) in the mental muscle after stimulation of the facial nerve and we examined electromyographic activity of the o. oculi and mental muscles synchronously. Furthermore, we studied the phenomenon of lateral spreading, also known as ephaptic transmission, between the different facial nerve branches. Patients with BPS had a prolonged R1 latency on the affected side in o. oculi and smaller mental CMAP amplitude as an indication of facial nerve damage and nerve fiber loss. This was not found in patients with HFS, who showed an increased amplitude of the R1 and R2 responses in o. oris. Patients with BPS showed only an increased R1 amplitude in o. oris. All patients had signs of synkinesia. Lateral spreading with different patterns was present in all patients with HFS and in half of the patients with BPS. Latencies of early and late responses showed no differences between HFS and BPS. In addition to alterations in facial nucleus excitability in both conditions, ectopic re-excitation of facial nerve axons in HFS may explain the differences in neurophysiological findings between HFS and BPS patients. A loss of control following synaptic stripping may also be a contributing factor.     

Prognosis and course of Bell's palsy

Summary The clinical picture of ischemic palsy of the facial nerve was analyzed by symptoms in 87 patients. The level of the lesion of the facial nerve in the channel was determined by topesthesia. Mutagenic disorder usually causes incomplete or defective recovery. The speed of development of palsy does not affect its course. Retroaural pain has little significance in the prognosis of palsy. Recorvery may be defective even in cases where no pain is present. If the nasopalpebral reflex is absent and Bell's phenomenon is positive in the 3rd week the prognosis is infavourable. In half the patients no precipitating or etiological factor was found.Clinical appraisal was made in five muscles (M. frontalis, M. orbicularis oculi et oris, M. zygomaticus, M. depressor labii inferioris). The patients were divided into three groups according to the degree of their recovery: complete, incomplete and defective recovery. Recovery was defective in elderly patients with vascular hypertension. Voluntary activity in Group 1 (complete recovery) is symmetrical by the 1st–2nd month and in Group 2 (incomplete recovery) by the 5th–7th month; in Group 3 it is permanently insufficient.     

Lateral spread response of different facial muscles during microvascular decompression in hemifacial spasm

ObjectiveInterpreting lateral spread response (LSR) during microvascular decompression (MVD) for hemifacial spasm (HFS) is difficult when LSRs observed in different muscles do not match. We aimed to analyze LSR patterns recorded in both the orbicularis oris (oris) and mentalis muscles and their relationships with clinical outcomes.MethodsThe data of 1288 HFS patients who underwent MVD between 2015 and 2018 were retrospectively reviewed. LSR was recorded in the oris and mentalis muscles through centrifugal stimulation of the temporal branch of the facial nerve after preoperative mapping. The disappearance of LSR following surgery, clinical outcomes, and the characteristics of LSR in oris were analyzed.ResultsAfter surgery, LSR remained in 100 (7.7%) and 279 (21.6%) of the mentalis and oris muscles, respectively. The postoperative outcome correlated with LSR disappearance in the mentalis, not with that in the oris.ConclusionLSR patterns differed in each muscle and may not be correlated with clinical outcomes. LSR in the mentalis and oris muscles should be interpreted differently.SignificanceWe describe a monitoring protocol characterized by preoperative facial nerve mapping, antidromic stimulation, and recording from multiple muscles. We analyze differences in LSRs in the mentalis and oris muscles and suggest technical points for interpretation.     

Uncrossed cortico-muscular projections in humans are abundant to facial muscles of the upper and lower face,but may differ between sexes

It is a popular concept in clinical neurology that muscles of the lower face receive predominantly crossed cortico-bulbar motor input, whereas muscles of the upper face receive additional ipsilateral, uncrossed input. To test this notion, we used focal transcranial magnetic brain stimulation to quantify crossed and uncrossed cortico-muscular projections to 6 different facial muscles (right and left Mm. frontalis, nasalis, and orbicularis oris) in 36 healthy right-handed volunteers (15 men, 21 women, mean age 25 years). Uncrossed input was present in 78% to 92% of the 6 examined muscles. The mean uncrossed: crossed response amplitude ratios were 0.74/0.65 in right/left frontalis, 0.73/0.59 in nasalis, and 0.54/0.71 in orbicularis oris; ANOVA p>0.05). Judged by the sizes of motor evoked potentials, the cortical representation of the 3 muscles was similar. The amount of uncrossed projections was different between men and women, since men had stronger left-to-left projections and women stronger right-to-right projections. We conclude that the amount of uncrossed pyramidal projections is not different for muscles of the upper from those of the lower face. The clinical observation that frontal muscles are often spared in central facial palsies must, therefore, be explained differently. Moreover, gender specific lateralization phenomena may not only be present for higher level behavioural functions, but may also affect simple systems on a lower level of motor hierarchy.     

Investigation of unilateral facial weakness: magnetic stimulation of the proximal facial nerve and of the face-associated motor cortex

Summary Twenty-four patients with unilateral facial weakness of various aetiologies were investigated using a magnetic stimulator to stimulate the proximal segment of the facial nerve directly (short latency response) and also to activate the facial motoneurons bilaterally via corticonuclear pathways by placing the stimulating coil over the motor cortex (long latency responses). Electromyographic recordings were taken from both mentalis muscles using concentric needle electrodes. Seventeen patients were investigated at various times after onset of idiopathic facial palsy (Bell's palsy). In the acute stage (less than 5 days after onset) short and long latency responses on the paretic side were abnormal, being absent in all but one patient, in whom the short latency response was delayed. These abnormal responses were the earliest neurographic correlate for nerve conduction block. In 4 out of 9 patients seen up to 30 days after onset of palsy, trans-synaptically evoked long latency responses were absent. In patients examined more than 2 months after onset, long latency responses could always be obtained and, in 5 of 8 patients, short latency responses could also be elicited, indicating a return of the direct excitability of the nerve. Five patients with cerebral hemisphere lesions causing mild unilateral facial weakness had absent long latency responses when stimulating over the affected hemisphere, but normal bilateral long latency responses following stimulation over the unaffected cerebral hemisphere; short latency responses were normal. Magnetic stimulation of the brain and of the facial nerve can differentiate between central and peripheral causes of unilateral facial weakness and may prove useful in the early assessment of the degree of conduction block in Bell's palsy.Supported by the Deutsche Forschungsgemeinschaft     

Hemihypoglossal-facial nerve anastomosis for facial nerve palsy

BACKGROUND AND PURPOSE : Commonly used classic hypoglossal (CN XII) to facial nerve (CN VII) anastomosis has the disadvantage of tongue hemiatrophy. Thus, various attempts have been made to modify this method to reduce the tongue damage. The aim of this report was to present the results of hemihypoglossal-facial nerve anastomosis (HHFA) technique in relation to facial muscles reanimation and hemitongue atrophy. MATERIAL AND METHODS : The first 7 consecutive patients who underwent CN VII anastomosis with half of the CNXII, for which the follow-up period exceeded 12 months, were analysed. During the procedure, CN VII was transected as proximally as possible after drilling the mastoid process. CN XII was separated longitudinally into two parts at a short distance to allow suture of the stumps without any tension. One half of CN XII was transected and sutured to the distal stump of CN VII. Recovery from facial palsy was quantified with the House-Brackmann grading system (HB). Tongue function was assessed according to the scale proposed by Martins. RESULTS : Features of initial reinnervation of facial muscles were visible after 6 months in all 7 patients. All patients achieved satisfactory outcome of CN VII regeneration (HB grade III) until the last control examination (12-27 months after surgery, mean 16). No or minimal tongue atrophy without deviation (grades I-II according to the Martins scale) was found in 4 patients. Mild hemiatrophy with tongue deviation < 30 degrees (grade III) was visible in 3 patients. CONCLUSIONS : In our experience, HHFA is effective treatment of facial palsy and gives a chance to reduce damage of the tongue.     

Unmasking of the trigemino-accessory reflex in accessory facial anastomosis

OBJECTIVE: To evaluate the possible blink reflex responses in facial muscles reinnervated by the accessory nerve. METHOD: Eleven patients with a complete facial palsy were submitted to a surgical repair by an accessory facial nerve anastomosis (AFA). In this pathological group, blink reflex was studied by means of percutaneous electrical stimulation of the supraorbital nerve and recording from the orbicularis oculi muscle. A control group comprised seven normal people and seven patients with a complete Bell's facial palsy; in this group, responses on the sternocleidomastoideus (SCM) muscles were studied after supraorbital nerve stimulation. RESULTS: All the patients with AFA showed a consistent degree of facial reinnervation. Ten out of the 11 patients with AFA showed reflex responses; in six, responses were configured by a double component pattern, resembling the R1 and R2 components of the blink reflex; three patients had an R1-like response and one patient showed a unique R2 component. Mean values of latencies were 15.2 (SD 4.6) ms for the R1 and 85.3 (SD 9.6) ms for the R2. In the control group, eight out of 14 people had evidence of reflex responses in the SCM muscles; these were almost exclusively configured by a bilateral late component (mean latency 63.5 (SD15.9) ms) and only one of the subjects showed an early response at 11 ms. CONCLUSION: The trigemino-accessory reflex response in the pathological group was more complex and of a significantly higher incidence than in the control group. These differences could be tentatively explained by a mechanism of synaptic plasticity induced by the impairment of the efferent portion of the reflex. This could unmask the central linking between the trigeminal and the accessory limbs of the reflex. The findings described could be a demonstration of neurobionomic function in the repairing process of the nervous system.     

The silent period induced by transcranial magnetic stimulation in muscles supplied by cranial nerves: normal data and changes in patients.

The silent period induced by transcranial magnetic stimulation of the sensorimotor cortex (Magstim 200, figure of eight coil, loop diameter 7 cm) in active muscles supplied by cranial nerves (mentalis, sternocleidomastoid, and genioglossus) was studied in 14 control subjects and nine patients with localised lesions of the sensorimotor cortex. In the patients, measurements of the silent period were also made in the first dorsal interosseus and tibialis anterior muscles. In the controls, there was a silent period in contralateral as well as ipsilateral cranial muscle and the duration of the silent period increased with increasing stimulus intensities. The mean duration of the silent period was around 140 ms in contralateral mentalis muscle and around 90 ms in contralateral sternocleidomastoid muscle at 1.2 x threshold stimulation strengths. Whereas the duration of the silent period in ipsilateral mentalis muscle was shorter than on the contralateral side it was similar on both sides in sternocleidomastoid muscle. In patients with focal lesions of the face associated primary motor cortex and corresponding central facial paresis, the silent period in mentalis muscle was shortened whereas it was unchanged or prolonged in limb muscles (first dorsal interosseus, tibialis anterior) with stimulation over the affected hemisphere. By contrast, in a patient with a lesion within the parietal cortex, the silent period in mentalis muscle was prolonged with stimulation of the affected side.     

Silent period in the mentalis muscle induced by facial nerve and cutaneous stimulation.

The aim of this study was to demonstrate that silent periods of the mentalis muscle are induced after facial nerve stimulation and cutaneous stimulation in normal subjects. When the marginal mandibular branch of the facial nerve and the cutaneous nerve in areas adjacent to the lower lip were stimulated during slight voluntary contraction of the mentalis muscle, silent periods were elicited with surface electrodes on the mentalis muscle. The early phase and the late phase of the silent period were elicited by marginal mandibular branch stimulation. The early phase of the silent period was recognized following the F waves and it disappeared at 36.3 msec. The average duration of the late phase of the silent period was 59.2 msec, with an average latency of 62.5 msec. Only the late phase of the silent period after cutaneous stimulation could be elicited, with a duration and latency of 55.9 msec and 54.0 msec respectively. The authors conclude that the silent period is able to be elicited in the mentalis muscle by peripheral nerve stimulation, and is one of the late responses in facial muscles.