Contralateral reinnervation of midline muscles in facial paralysis.

We report on a patient with recovery of activity of the left orbicularis oris and nasalis muscles 3 months after a complete left facial palsy. Stimulation of the affected facial nerve evoked no responses, whereas contralateral facial nerve stimulation showed polyphasic responses with very long latencies in the nasalis and orbicularis oris muscles. Needle electromyography (EMG) revealed abnormal spontaneous activity in the left orbicularis oris muscle. The motor unit action potentials on the left side of the face could be recruited only during marked contraction of the corresponding muscles on the right and were of low voltage and polyphasic ("nascent potentials"). Contralateral reinnervation is probably due to sprouting of terminal branches crossing the midline of the face and innervating bundles of muscle fibers on the affected side. This phenomenon seems unfamiliar to most clinicians. Whether the activity is due to conduction along nerve fibers or muscle fibers crossing the midline is discussed.     

Contralateral reinnervation in Bell's palsy. A case report.

Congenital lesion of the left facial nerve trunk has been investigated in a 30-year-old woman. Upon stimulation of the left facial nerve, no response was evoked in any of the mimic muscles. The patient was able to perform voluntary contractions of the left corrugator glabellae muscle and of the left corner of the orbicular oral muscle; these contractions were recorded electromyographically. The stimulation of the right facial nerve elicited responses in the referred left mimic muscles. This circumstance indicated their activity to be due to contralateral reinnervation by the intact facial nerve. The blink reflex examination evoked no response on the left side, while the blinik reflex on the right side was elicited with both its components, both upon ipsi- and contralateral stimulation.     

Contralateral facial palsy in a case of cervical zoster

Zusammenfassung Die Facialisparese beim Ramsay Hunt Syndrome und seinen Untergruppen wurde bisher stets ipsilateral zur Hauteruption beschrieben.Kelly berichtet von einer kontralateralen Facialisparese bei einem Zoster Oticus. Hier wird ein Fall von kontralateraler Facialisparese bei einem zervikalen Zoster dargestellt. Es handelt sich um eine 78jährige Patientin, die 2 Wochen nach linksseitigem Auftreten des Herpes Zoster im oberen Zervikalbereich eine periphere Facialisparese rechts entwickelte.Die möglichen pathogenetischen Zusammenhänge werden diskutiert.

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Research Fellow of the Alexander von Humboldt Foundation     

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.     

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     

Denervation and reinnervation in congenital brachial palsy.

Motor unit number estimation (MUNE) was shown to be useful in assessing the neurophysiological status of 18 subjects with congenital brachial palsy. This was especially so since conventional M-wave measurements may give misleading impressions as to the extent of motor axon regeneration. In most subjects the involvement of sensory nerve fibers indicated that the traumatic lesions included postganglionic segments of the fibers, with or without preganglionic damage. In a minority the lesions were purely preganglionic. Digital sensory nerve involvement was more in a mediolateral direction, consistent with greater damage to the uppermost elements in the brachial plexus. In 5 individuals, MUNE and sensory testing showed that there had been trauma to the supposedly unaffected arm. Discrepancies between sensory and motor results suggested that reinnervation of the biceps brachii muscle was greater than that of the intrinsic muscles of the hand. In one subject examined serially, reinnervation of the hand muscles was detected by 10 months and continued in the hypothenar muscles for the next 6 years.     

Contralateral early blink reflex in patients with facial nerve palsy: indication for synaptic reorganization in the facial nucleus during regeneration.

Fifty patients with Bell's palsy and 30 patients with etiologically different symptomatic peripheral facial nerve palsy were studied by means of electrically evoked blink reflexes 1-23 days after onset of paresis. Their results were compared with a normal control group of 30 healthy subjects. In a significant number of patients (64% in Bell's palsy and 53% in symptomatic facial nerve palsy) a contralateral early blink reflex response (R1) could be elicited upon stimulation of the normal side as compared to 13% in the control group. It is suggested that this result may be explained by synaptic reorganization of the facial nucleus leading to functional unmasking of pre-existing crossed trigemino-facial reflex pathways during regeneration. This view is in line with previous experimental data in animals on the time course of structural changes in the facial nucleus after lesioning of the ipsilateral facial nerve.     

Selective reinnervation of somatotopically appropriate muscles after facial nerve transection and regeneration in the neonatal rat

The organization of the facial motor nucleus (FMN) has been examined after transection and regeneration of the facial nerve (FN) in neonatal and adult rats. In one series of experiments, horseradish peroxidase (HRP) was applied bilaterally to the superior or inferior buccal ramus 5 months after neonatal FN transection. In another series of experiments, wheat germ agglutinin-horseradish peroxidase conjugate was injected in selected vibrissae follicular muscles on both sides in animals surviving 5 months after FN transection at the neonatal or adult stage. The number and distribution of HRP-labeled cell bodies in the FMN after regeneration was compared with the contralateral side. On the uninjured side, labeled neurons were somatotopically organized. Ipsilateral to nerve injury the number of labeled cells was markedly reduced after neonatal nerve transection, but somatotopy was preserved. However, after nerve lesion at the adult stage, no significant loss of motoneurons occurred, but motor nucleus somatotopy was not maintained. Two alternative principal explanations are proposed for the re-establishment of the normal somatotopy after neonatal injury: that regenerating axons grow in a random fashion but inappropriate connections are subsequently eliminated or that regenerating axons of surviving neurons immediately follow a pathway leading to the appropriate muscle.     

Topographically selective reinnervation of adult mammalian skeletal muscles

In 2 rat muscles, serratus anterior and the diaphragm, the rostrocaudal axis of the motor pool is mapped onto the rostrocaudal axis of the muscle's surface (Laskowski and Sanes, 1987a). One possible basis for this orderly topography is that motor axons and intramuscular structures bear labels that favor connectivity among positionally matched partners. To test for the existence of such labels, we asked whether axons would selectively reinnervate appropriate portions of the muscles following nerve transection. We found that, on average, rostral and caudal halves of each muscle were preferentially reinnervated by axons from the rostral and caudal halves of its motor pool, respectively. In the serratus anterior, reinnervation was more selective following denervation in neonates than following denervation in adults, although in neither case was the normal pattern of innervation reestablished completely. These results show that motor axons can selectively reinnervate adult rat muscles, and support the idea that positional cues play a role in organizing neuromuscular topography.     

Facioscapulohumeral dystrophy: jitter in facial muscles.

Motor end plate jitter was studied by single fibre EMG in the orbicularis oculi muscle of eight patients with facioscapulohumeral dystrophy activated by extramuscular nerve stimulation. The jitter was found to be slightly larger in comparison with the normal controls, although still within the normal limits in each patient. The findings are considered to indicate absence of any significant neuromuscular transmission disturbance, inflammatory or regenerative process, or reinnervation in progress. There was no evidence of muscle fibre conduction abnormality even in very weak muscle.     

Delayed facial palsy after head injury.

Where facial palsy follows head injury after many days, the mechanism is not clear, and there has been no detailed study on this condition. In this prospective study, an attempt is made to estimate this complication of head injury, and to study its pathogenesis, natural history, prognosis, and sequelae which differ markedly from Bell's palsy. It has a much worse prognosis and so surgical decompression should be considered early in this condition.     

Movement disorders in patients with peripheral facial palsy.

Acute unilateral facial paralysis is usually a benign neurological condition that resolves in a few weeks. However, it can also be the source of a transient or long-lasting severe motor dysfunction, featuring disorders of automatic and voluntary movement. This review is organized according to the two most easily recognizable phases in the evolution of facial paralysis: (1). Just after presentation of facial palsy, patients may exhibit an increase in their spontaneous blinking rate as well as a sustained low-level contraction of the muscles of the nonparalyzed side, occasionally leading to blepharospasm-like muscle activity. This finding may be due to an increase in the excitability of facial motoneurons and brainstem interneurons mediating trigeminofacial reflexes. (2). If axonal damage has occurred, axonal regeneration beginning at approximately 3 months after the lesion leads inevitably to clinically evident or subclinical hyperactivity of the previously paralyzed hemifacial muscles. The full-blown postparalytic facial syndrome consists of synkinesis, myokymia, and unwanted hemifacial mass contractions accompanying normal facial movements. The syndrome has probably multiple pathophysiological mechanisms, including abnormal axonal branching after aberrant axonal regeneration and enhanced facial motoneuronal excitability. Although the syndrome is relieved with local injections of botulinum toxin, fear of such uncomfortable contractions may lead the patients to avoid certain facial movements, with the implications that this behavior might have on their emotional expressions.     

Denervation pattern of three mimic muscles in Bell's palsy.

OBJECTIVE: To explore the presence and grade of denervation in three mimic muscles in facial nerve palsy. METHODS: The frontalis, orbicularis oculi (OO), and mentalis muscles were explored in 54 patients with Bell's palsy, after 30 days from the beginning of symptoms. Concentric needle electromyography, including fibrillation detection, was performed in the three muscles on the affected side. Compound muscle action potentials (CMAP) were recorded on both sides and a CMAP ratio was calculated from each muscle. The House-Brackman scale was used to assess the initial clinical evaluation and the follow-up until recovery. RESULTS: Fibrillation was recorded in 32 patients on the 30th day after the onset and was present in 100% of mentalis and in 90% of frontalis, but in only 34% of OO, a statistically significant difference. The grade of fibrillation in OO was also statistically lower from those in the other two muscles. The 32 patients were grouped according to the presence (A) or not (B) of fibrillation in OO. In group A, CMAP ratios (affected/normal side) did not differ significantly among the three muscles. However, in group B they were significantly greater in OO and frontalis than in mentalis. In between-group comparison, group B muscles had significantly higher CMAP ratios, lower degree of fibrillation, and better functional recovery. CONCLUSION: In facial palsy, the presence and grade of fibrillation in OO are lower than in frontalis and mentalis muscles and prognosis is more favorable for the non-fibrillating OO group of patients.     

Motor control deficits of orofacial muscles in cerebral palsy.

Voluntary control of the masseter and orbicularis oris superioris muscles was examined in able bodied and cerebral palsied subjects using visual tracking tasks. A smoothed measure of muscle activity (the full-wave rectified and low-pass filtered electromyogram) was presented as a marker on a computer display screen and the subjects could control the vertical position of the marker by voluntarily altering the level of isometric contraction of one of the muscles. A target marker was also displayed on the screen and the subjects were required to follow or "track" the irregular movements of this target with the response marker. Their success in aligning the response marker with the target was analysed for these orofacial muscles. The masseter is influenced by muscle spindle based reflexes, while the orbicularis oris superioris lacks such reflex control. The cerebral palsied subjects displayed similarly poor control over both muscles, implying that their voluntary motor deficits are not related to abnormal muscle spindle based reflexes. It is suggested that the impairment may be related to perceptual-motor integration.     

Statistical studies on 120 cases of facial palsy.

During the past five years (Jan. 1928 to Jul. 1932) we have had 120 cases of facial palsy under our personal observation, of which we wish to publish the results of statistical researches.