Value of the facial nerve latency test in the prognosis of childhood Bell's palsy

In the present study we evaluated the facial nerve latency test (FNLT) as a prognostic tool in cases of childhood Bell's palsy. Twenty-five children aged 4–14 years were studied. We divided our subjects into three groups according to duration of latency time (LT). Group A patients had an LT within the normal range, with average of 3.27 ms, group B a slightly prolonged LT averaging 5.7 ms, and group C a markedly prolonged LT averaging 10.5 ms. Analysis of the recovery index by group showed that group A patients experienced complete and quick recovery, while in group B 50% had complete but delayed recovery and 50% slightly impaired facial nerve function, and in group C 50% had slightly impaired function and 50% incomplete recovery. The more prolonged the LT, the worse the clinical results. The FNLT is thus a valuable prognostic tool in cases of Bell's palsy in childhood.     

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     

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.     

Evaluation of proximal facial nerve conduction by transcranial magnetic stimulation.

A magnetic stimulator was used for direct transcutaneous stimulation of the intracranial portion of the facial nerve in 15 normal subjects and in patients with Bell's palsy, demyelinating neuropathy, traumatic facial palsy and pontine glioma. Compound muscle action potentials (CMAPs) thus elicited in the orbicularis oris muscle of controls were of similar amplitude but longer latency (1.3 SD 0.15 ms) compared with CMAPs produced by conventional electrical stimulation at the stylomastoid foramen. No response to magnetic stimulation could be recorded from the affected side in 15 of 16 patients with Bell's palsy. Serial studies in two patients demonstrated that the facial nerve remained inexcitable by magnetic stimulation despite marked improvement in clinical function. In the patient with a pontine glioma, the CMAP elicited by transcranial magnetic stimulation was of low amplitude but normal latency. In six of seven patients with demyelinating neuropathy, the response to intracranial magnetic stimulation was significantly delayed. Magnetic stimulation produced no response in either patient with traumatic facial palsy. Although the precise site of facial nerve stimulation is uncertain, evidence points to the labyrinthine segment of the facial canal as the most likely location.     

Reinnervation by the contralateral facial nerve in patients with peripheral facial palsy

Introduction: Reinnervation activity is triggered after complete unilateral peripheral facial palsy (PFP). Methods: In 27 patients with PFP we recorded electromyographic activity with a concentric needle electrode inserted 1 cm lateral to the oral commissure of the affected side. We applied electrical stimuli to the unaffected (contralateral) facial nerve from the tragus to the mid‐lower lip and measured the response latency variability and segmental conduction velocity. Results: Responses to electrical stimulation of the unaffected facial nerve were found in all patients. Mean conduction velocity was 49.6 ± 6.2 m/s between tragus and oral commissure, and 6.0 ± 1.9 m/s between oral commissure and mid‐lower lip. Latency variability was 0.27 ms to facial nerve stimulation and 0.08 ms to oral commissure stimulation. Conclusion: Short distance sprouting of axons that innervate muscle fibers, which originate from the unaffected facial nerve, results in propagation of impulses to muscle fibers in the midline. Muscle Nerve 2011     

Diagnostic relevance of transcranial magnetic and electric stimulation of the facial nerve in the management of facial palsy.

OBJECTIVE: Earlier investigations have suggested that isolated conduction block of the facial nerve to transcranial magnetic stimulation early in the disorder represents a very sensitive and potentially specific finding in Bell's palsy differentiating the disease from other etiologies. METHODS: Stimulation of the facial nerve was performed electrically at the stylomastoid foramen and magnetically at the labyrinthine segment of the Fallopian channel within 3 days from symptom onset in 65 patients with Bell's palsy, five patients with Zoster oticus, one patient with neuroborreliosis and one patient with nuclear facial nerve palsy due to multiple sclerosis. RESULTS: Absence or decreased amplitudes of muscle responses to early transcranial magnetic stimulation was not specific for Bell's palsy, but also evident in all cases of Zoster oticus and in the case of neuroborreliosis. Amplitudes of electrically evoked muscle responses were more markedly reduced in Zoster oticus as compared to Bell's palsy, most likely due to a more severe degree of axonal degeneration. The degree of amplitude reduction of the muscle response to electrical stimulation reliably correlated with the severity of facial palsy. CONCLUSIONS: Transcranial magnetic stimulation in the early diagnosis of Bell's palsy is less specific than previously thought. While not specific with respect to the etiology of facial palsy, transcranial magnetic stimulation seems capable of localizing the site of lesion within the Fallopian channel. SIGNIFICANCE: Combined with transcranial magnetic stimulation, early electrical stimulation of the facial nerve at the stylomastoid foramen may help to establish correct diagnosis and prognosis.     

Electrodiagnostic studies of the facial nerve in peripheral facial palsy and hemifacial spasm

Electrodiagnostic (EDX) assessment is one of the most important aspects in the evaluation of the two most common disorders of the facial nerve: facial palsy and hemifacial spasm. Facial palsy is usually an acute disorder that resolves in a few weeks but, in a number of cases, leads to a postparalytic facial syndrome featuring muscle synkinesis, myokymia, and involuntary mass contractions of muscles on the affected side. Hemifacial spasm is usually a chronic disorder characterized by paroxysms of involuntary, clonic, and synchronous twitching of all facial muscles on the affected side. EDX studies provide information on lesion location and severity, pathophysiology underlying the two disorders, and differential diagnosis between syndromes presenting with abnormal facial muscle activity. This monograph is intended to describe the most relevant EDX findings in the two disorders and the most appropriate timing for the examinations in order to provide useful information for prognosis and therapeutic decision-making.     

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.     

The value of intraoperative facial nerve electromyography in predicting facial nerve function after vestibular schwannoma surgery

The prognostic significance of intraoperative facial nerve electromyography (EMG) changes is not well-established in vestibular schwannoma (VS) surgery. We studied facial nerve EMG with a threshold >0.05 mA and performed subgroup analyses based on tumor size, resection approach, and extent of resection, for prediction of long-term facial nerve outcome. A total of 477 surgically treated VS patients were included. Elevated stimulation threshold exceeding >0.05 mA is a highly specific (90%), but very insensitive (29%) finding in this cohort. The positive predictive value and negative predictive values (NPV) of facial nerve EMG for detection of permanent facial palsy are 68% and 63%, respectively. The NPV decreased with increasing tumor size (72% versus [vs.] 64% vs. 53%) due to the increasing prevalence of post-operative facial nerve palsy in these patients. In conclusion, while facial nerve EMG is a critical adjunct for locating the facial nerve intraoperatively, its predictive value for facial nerve function remains to be determined.     

神经肌电图对特发性面瘫治疗及预后评估的研究

目的探讨神经肌电图(神经电图electroneurography,ENG和肌电图electromyography,EMG)在特发性面瘫治疗及预后评估中的价值。方法采用丹麦生产的keypointⅣ肌电图仪对96例确诊为特发性面瘫的患者进行患侧与健侧ENG、EMG检测,分别记录患侧面神经颞支、颧支、颊支的运动传导潜伏期、波幅以及所支配的额肌、眼轮匝肌、口轮匝肌的肌电图情况,并与自身健侧作对比。结果特发性面瘫患者患侧面神经运动传导潜伏期延长、M波波幅降低,与自身健侧相比,差异有统计学意义(P<0.05)。波幅下降<70%、NCV(神经传导速度)减慢<20%、EMG大致正常的轻度患者,3个月内面肌完全恢复,治愈率100%;波幅下降70%～90%、NCV减慢20%～50%、EMG呈部分神经源性损害的中度患者,3个月内大部分可完全恢复,治愈率87.8%;波幅下降>90%、NCV减慢>50%、EMG呈部分或完全神经源性损害的中重度患者,3个月内面肌完全恢复者为50%;诱发电位消失、NCV引不出、EMG呈完全神经源性损害的重度患者,3个月内面肌完全恢复者为25%。结论 ENG和EMG检测对特发性面瘫的神经损伤、面肌恢复等预后评估有重要价值,能对临床治疗提供客观依据。     

Myokymic discharges and enhanced facial nerve reflex responses after recovery from idiopathic facial palsy.

A functional disorder of facial muscle activity commonly occurs in patients after recovery from Bell's palsy with axonal degeneration. The postparalytic facial dysfunction is probably related to the aberrant growing of regenerating axons, although other theories such as ephaptic transmission, spontaneous generation of impulses, and enhancement of motoneuron excitability should also be considered. In this work, we have carried out a comparative electrophysiological study of both sides of the face in 23 patients who had recovered from a unilateral Bell's palsy with axonal degeneration. At rest, spontaneous firing of motor units was observed in muscles of the previously paralyzed side. Direct motor responses to facial nerve stimulation were smaller in the muscles of the previously paralyzed side, but reflex responses obtained in the same muscles by stimulation of either the facial or trigeminal nerve were larger when compared with those of the contralateral side. These data indicate that patients with "postparalytic facial dysfunction" may have an increased background muscle activity, as well as an enhanced recruitment of facial motoneurons to reflex activation in the side of the previous paralysis. These findings are compatible with an enhanced level of motoneuron excitability in the facial nucleus.     

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.     

Neurophysiological evaluation of trigeminal and facial nerves in patients with chronic inflammatory demyelinating polyneuropathy

Cranial neuropathy is clinically uncommon in patients with chronic inflammatory demyelinating polyneuropathy (CIDP), but there is little information on the neurophysiological examination of cranial nerve involvement. To determine the incidence of trigeminal and facial nerve involvement in patients with CIDP, the direct response of the orbicularis oculi muscle to percutaneous electric stimulation of the facial nerve and the blink reflex (induced by stimulation of the supraorbital nerve) were examined in 20 CIDP patients. The latency of the direct response was increased in 12 patients (60%) and an abnormal blink reflex was observed in 17 patients (85%). There was no correlation between electrophysiological findings and the latencies of the direct and R1 responses and disease duration or clinical grade in CIDP patients. Nevertheless, the prevalence of subclinical trigeminal and facial neuropathy is extremely high in patients with CIDP when examined by neurophysiological tests.     

Chronic vascular irritation of the facial nerve causes facial spasm in rats

Abstract

The abnormal muscle response, elicited by electrical stimulation of one branch of the facial nerve and recorded from muscles innervated by another branch, has been used previously as an objective sign of hemifacial spasm in the development of animal models of this disorder. In the present study we recorded spontaneous electromyographic activity from the orbicularis oculi muscle from both sides in rats in which a demyelination of the peripheral portion of the facial nerve and vascular contact had been made previously. The root mean square value of the electromyographic activity on the affected side was significantly larger than that on the unaffected side in all rats in which the vascular irritation had caused the abnormal muscle response to appear. The results support our earlier finding that vascular contact together with demyelination of the peripheral facial nerve can cause the development of signs of hemifacial spasm, including involuntary muscle contractions. [Neurol Res 1994; 16: 284-288]     

Peripheral facial nerve paralysis in children: the value of routine diagnostic work-up studies

Acute facial nerve paralysis is a relatively common pediatric disorder. Idiopathic facial nerve palsy (Bell's palsy) has to be distinguished from other etiologies. Retrospective review of the results of routine diagnostic work-up studies of our patients, failed to reveal any clinically significant abnormalities and did not provide more data as far as etiology or indication for management. Significant history and positive findings on physical examination should direct the physician towards specific diagnostic procedures.     

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.     

Altered axonal excitability properties in facial palsy

Introduction: Axonal excitability measures give insight into the biophysical properties of peripheral nerve axons. In this study we applied these techniques to the study of facial palsy. Methods: Thirty patients with established facial palsy due to unresolved Bell's palsy or herpes zoster (>6 months duration), tumor invasion of the facial nerve, or traumatic facial nerve injury were assessed using facial nerve excitability techniques. Results: Full recordings were obtained in 23 patients (15 unrecovered Bell's palsy or herpes zoster, 5 trauma, 3 tumor‐related). Compared with normal controls, the facial palsy group demonstrated changes in stimulus response properties, threshold electrotonus, refractoriness, superexcitability, and I/V slope. Depolarizing threshold electrotonus distinguished between viral and non‐viral etiologies on subgroup analysis. Discussion: In this cross‐sectional study, established facial palsy demonstrated findings similar to those seen in studies of regenerated axons. The improved understanding of underlying axonal characteristics offered by the technique may guide future treatment. Muscle Nerve 57 : 268–272, 2018     

Amniotic membrane covering for facial nerve repair

Amniotic membranes have been widely used in ophthalmology and skin injury repair because of their anti-inflammatory properties. In this study, we measured therapeutic efficacy and determined if amniotic membranes could be used for facial nerve repair. The facial nerves of eight rats were dissected and end-to-end anastomosis was performed. Amniotic membranes were covered on the anastomosis sites in four rats. Electromyography results showed that, at the end of the 3 rd and 8 th weeks after amniotic membrane covering, the latency values of the facial nerves covered by amniotic membranes were significantly shortened and the amplitude values were significantly increased. Compared with simple facial nerve anastomosis, after histopathological examination, facial nerve anastomosed with amniotic membrane showed better continuity, milder inflammatory reactions, and more satisfactory nerve conduction. These findings suggest that amniotic membrane covering has great potential in facial nerve repair.     

Long-term outcome in children with congenital unilateral facial nerve palsy

During a 20-year period (1980 - 1999) 12 children with isolated congenital unilateral facial nerve palsy were seen at our hospital. The only child delivered by forceps made a full recovery from his palsy within two months, whereas functional improvement in patients with non-traumatic delivery was generally poor. In two patients the palsy affected predominantly the upper periocular region. In 10 children the lower facial region seemed to be mainly involved. Cognitive outcome was within normal limits, with one exception. Conventional neuroimaging was not contributory to the understanding of the pathogenetic mechanisms. We conclude that the majority of congenital unilateral facial nerve palsies are not of traumatic origin and carry a poor functional prognosis.     

周围性面瘫的手术治疗浅析

周围性面瘫是临床上常见的一种疾病,大多数经过内科治疗是可以治愈的,但对于少数内科治疗效果不佳者,最终尚需手术治疗。由于病因、病程等不同,手术时机、方式等尚有进一步探讨的必要。我们通过对不同病因、不同病程的4例患者进行了手术治疗,效果满意。通过我们的操作体会认为面神经吻合术为早期外伤性面瘫治疗的最佳选择,阔筋膜静态悬吊术对于晚期面瘫病例可改善部分症状,为恢复面瘫静态外观的有效方法,不失为可供选择的术式。