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The localization of facial motor impairment in sporadic Möbius syndrome.

OBJECTIVE: To investigate the neurophysiologic aspects of facial motor control in patients with sporadic Möbius syndrome defined as nonprogressive congenital facial and abducens palsy. METHODS: The authors assessed 24 patients with sporadic Möbius syndrome by performing a complete clinical examination and neurophysiologic tests including facial nerve conduction studies, needle electromyography examination of facial muscles, and recording of the blink reflex and of the trigeminofacial inhibitory reflex. RESULTS: Two distinct groups of patients were identified according to neurophysiologic testing. The first group was characterized by increased facial distal motor latencies (DMLs) and poor recruitment of small and polyphasic motor unit action potentials (MUAPs). The second group was characterized by normal facial DMLs and neuropathic MUAPs. It is hypothesized that in the first group, the disorder is due to a rhombencephalic maldevelopment with selective sparing of small-size MUs, and in the second group, the disorder is related to an acquired nervous injury during intrauterine life, with subsequent neurogenic remodeling of MUs. The trigeminofacial reflexes showed that in most subjects of both groups, the functional impairment of facial movements was caused by a nuclear or peripheral site of lesion, with little evidence of brainstem interneuronal involvement. CONCLUSION: Two different neurophysiologically defined phenotypes can be distinguished in sporadic Möbius syndrome, with different pathogenetic implications.

Adolescent↗

Surgical simulation of facial paralysis.

We are developing a prototype of a surgical simulation system for restoring facial expression lost in cases of facial paralysis. Correcting facial paralysis requires careful planning of surgery procedures and accurate prediction of the surgical results. So far techniques to perform this task largely relied on the physician's experience, and there were few quantitative data to refer to. The system we propose is finally aimed at helping the surgeon plan the surgery and predict the results. The 3D model of the face used in our system is generated directly from the CT scan of the patient. The face model consists of skin, skull and selected facial muscles based on anatomy. The mass and spring lattice approach is used to give physical attributes to the face model. The present prototype system lets the user directly manipulate graphical representations of facial expression.

Computer Graphics↗

Computed tomography of the buccomasseteric region: 1. Anatomy.

The differential diagnosis to consider in a patient presenting with a buccomasseteric region mass is rather lengthy. Precise preoperative localization of the mass and a determination of its extent and, it is hoped, histology will provide a most useful guide to the head and neck surgeon operating in this anatomically complex region. Part 1 of this article describes the computed tomographic anatomy of this region, while part 2 discusses pathologic changes. The clinical value of computed tomography as an imaging method for this region is emphasized.

Cheek↗

Coordination of cranial motoneurons during mastication.

Mastication is the first stage of digestion and involves several motor processes such as food intake, intra-oral food transport, bolus formation and chewing in its broad sense. These complicated motor functions can be accomplished by the well-coordinated activities in various cranial motoneurons innervating the jaw, hyoid, tongue and facial muscles. The brainstem masticatory central pattern generator (CPG) plays a crucial role in generating basic activity patterns of these cranial motoneuron groups. However, descending inputs from higher brain (e.g., cerebral cortex) and mastication-generated peripheral sensory inputs also play important roles in modulating the activity pattern of each motoneuron so that the final motor outputs fit the environmental demand. In this review, we focus on the coordination of the trigeminal, facial and hypoglossal motoneurons during mastication. We first summarize findings showing the activity patterns of muscles innervated by these motoneurons during natural mastication, and then discuss the possible neural mechanisms underlying their coordinated activities during mastication.

Animals↗

Testosterone-induced acceleration of recovery from facial paralysis following crush axotomy of the facial nerve in male hamsters.

In this study, the effects of testosterone propionate (TP) on recovery from facial paralysis following crush axotomy of the facial nerve in male hamsters were examined. In the first experiment, TP (5 mg/ml sesame oil; 0.1 ml) was injected subcutaneously and on alternate days in one-half of the animals subjected to crush axotomies of the facial nerve, with the second half receiving vehicle alone. An accelerative effect of TP on recovery from facial paralysis was observed near the end of the first and beginning of the second week after crush axotomy. When the dosage and frequency were doubled in the next experiment, a greater accelerative effect of TP on recovery from facial paralysis was observed. In the last experiment, castrated animals were used in order to eliminate the endogenous source of the hormone and two different modes of hormone administration, TP implants vs TP injections, were compared. The results of that experiment indicate that continuous exposure to the hormone, in the form of subcutaneous implants of 100% crystalline TP, had the most pronounced effect on acceleration of recovery from facial paralysis. In addition, no differences in the responses of the castrated, axotomized animals and the normal, axotomized animals were found. This suggests that the presence of endogenous hormone contributes little to the acceleration of functional recovery observed with TP. Finally, the time course of the accelerative effect of TP suggests that the hormone is acting primarily at the level of the facial neuron, which contains androgen receptors, and perhaps secondarily at the level of the facial muscles, which are also known to contain androgen receptors.

Animals↗

Neuromuscular complications in patients given Pavulon (pancuronium bromide) during artificial ventilation.

This paper reports on 12 patients in a 3-year period (from 1st July 1980 to 1st July 1983) who were treated with artificial ventilation and with the muscle relaxant pancuronium bromide (Pavulon), over a period of 6 days or longer. After discontinuation of this drug these patients developed severe tetraparesis with areflexia, sometimes combined with disturbances of the extraocular and facial muscles and diffuse muscular atrophy, without sensory disturbances. Seven patients recovered completely after 2-5 months, two made an incomplete recovery and three died due to the primary disease. It is suggested that these neuromuscular complications were caused by prolonged high-dosage Pavulon treatment in combination with renal and hepatic disturbances and/or the use of aminoglucosides.

Adult↗

The management of oromandibular motor disorders and facial spasms with injections of botulinum toxin.

Although much work is yet to be done in this area, nine general conclusions can be derived: 1. Local site-of-injection side effects from botulinum toxin injections are rare, assuming proper technique is used. 2. The two most common medication-related side effects from botulinum toxin orofacial injections are alterations in salivary consistency and inadvertent weakness of the swallowing, speech, and facial muscles. These complications are injection site-specific (eg, more common with lateral pterygoid injections and palatal and tongue muscle injections) and dose-dependent problems. These problems are bothersome but are not contraindications for the therapy if it is needed. 3. The data presented in this article are mostly case series-based and open trial-based information that is promising, but randomized, blinded, controlled trials are needed to establish the true efficacy of this method for the orofacial motor and pain disorders. 4. The novice should begin with injection of muscles he or she can inject with low risk of incorrect placement. The hard-to-find muscles should be avoided when starting out. The novice clinician should inject and dissect a few cadavers to improve injection technique. 5. The general latency for botulinum toxin type A is 1 week, its duration is 2 to 3 months, and it is recommended that injection be done no more than once every 12 weeks to avoid development of antibodies against the toxin. 6. Depending on the target muscle, injection dose is 10 to 50 U of Botox type A per site with a total dose of 200 U in the masticatory system. More than this can be used (400 U maximum) if other sites in the head and neck are included in the injection protocol. 7. Regarding injecting painful muscles that do not exhibit palpable muscle hardness or EMG-determined spasticity or observable involuntary movements but have chronic myofascial trigger points or the patient localizes them as the site of their chronic daily headache pain, botulinum toxin injections might be helpful used in this manner, but conclusive data for this controversial application of botulinum toxin are still missing. 8. Hemifacial spasm has the largest number of open-label, clinical trials, some of which have a 10-year follow-up. The conclusions reached by all of these reports is that treatment of hemifacial spasm with repeated injections of botulinum toxin has been highly successful and that the dose and relative effect of the injections are stable over time. 9. Although EMG-guided injection may be useful, EMG is neither practical nor needed in most situations for orofacial injections because most of the orofacial muscles are easily palpable muscles or have definitive bony landmarks to help with the localization process.

Anti-Dyskinesia Agents↗

A case of myasthenia gravis proven by ultrastructural study.

Although light microscopic features of muscle are not pathognomonic in most cases of myasthenia gravis (MG), careful examination of neuromuscular junction by electron microscopy (EM) can reveal important clues for this disease. We report here a case of MG confirmed by EM study to emphasize that tissue diagnosis is still the best adjuvant to confirm the diagnosis. An 18-year-old female visited our hospital complaining of progressive muscle weakness for 3 years. She had difficulty in running, going upstairs and doing routine activities. Symptoms were aggravated with continuous work and resolved after rest. She had weakness of bilateral masseter and facial muscles and proximal portions of extremities without definite diurnal variation. Electromyography showed myopathic changes in proximal muscles of extremities. MG was considered but tensilon test was equivocal. Repetitive nerve stimulation tests revealed 20-30 percent decrease in responses to low and high rate stimulation. Muscle biopsy revealed selective type 2 atrophy. Ultrastructurally, abnormalities of neuromuscular junctions, i.e., wide primary synaptic cleft, and wide and shallow secondary synaptic clefts with mild myopathic features were present. These findings were pathognomonic for MG. Later, her symptoms were improved completely 3 months after thymectomy. The histologic finding of thymus was follicular hyperplasia.

Adolescent↗

Facial nerve paralysis after impacted lower third molar surgery: a literature review and case report.

Facial nerve paralysis (FNP) is the most common cranial nerve disorders and it results in a characteristic facial distortion that is determined in part by the nerves branches involved. With multiples etiologies, these included trauma, tumor formation, idiopathic conditions, cerebral infarct, pseudobulbar palsy and viruses. FNP during dental treatment is very rare and can be associated with the injection of local anesthetic, prolonged attempt to remove a mandibular third molar and subsequent infection. We report a case of a 21 years-old black woman who developed a Bell's palsy after an impacted third molar surgery under local anaesthesia, present a FNP classified like a grade IV by the House-Brackmann's grading system. The treatment was based of prescription of a cytidine and uridine complex (NUCLEO CMP tm) one tablet twice per day and a close follow up. Three months later that had beginning the treatment, the patient recovery her normal facial muscle activity.

Adult↗

Facial sensory evoked muscle potentials during labour. A continuous objective monitor of adequacy of analgesia?

We prospectively studied the relationship between upper facial sensory-evoked muscle potential amplitude, uterine contraction amplitude and heart rate in 20 healthy parturients during the first stage of labour. Monitoring began when minimal pain was reported and continued until severe pain occurred and extradural analgesia was established. Pain intensity was assessed by each patient using a 10 cm visual analogue score. Heart rate was recorded using a pulse oximeter. Sensory evoked muscle potential was derived from frontalis biopotentials that were rectified, integrated and digitised by an Anaesthesia and Brain activity Monitor (Datex, Helsinki, Finland). An additional signal filter was included in the pre-amplifier to improve the signal-to-noise ratio. The rms amplitude of successive 10s samples of sensory evoked muscle potential, as well as heart rate and the output from an external tocotransducer, were then graphically displayed to allow assessment of temporal relationships. The data were assessed using correlation analysis and hypergeometric probability distribution. Before extradural analgesia (mean pain score 7.5 cm, SD 1.5 cm) a significant relationship was demonstrated between sensory evoked muscle potential and uterine contraction, p < 0.001). No constant relationship was seen between heart rate and uterine contraction. Following extradural analgesia (mean pain scores of 2.1 cm, SD 1.3 cm) a variable relationship between sensory evoked muscle potential and uterine contraction amplitude, and heart rate and uterine contraction, was recorded. A continuous display of the relationship between filtered sensory evoked muscle potentials of the frontalis muscle and uterine contraction may, in the future, permit an objective assessment of the adequacy of analgesia following extradural analgesia for the pain of labour.

Adult↗

[Microsurgery of the facial nerve (author's transl)].

The extent and importance of facial paralysis is established by means of the diagnosis of the etiologic factors, the level of the nerve lesions and the condition of the facial muscles. Treatment depends on the analysis of these different elements. A survey of the methods of treatment is given with special reference to the cross-face nerve grafting. The results of the varied methods are reviewed. The substitutional procedures are listed.

Adult↗

One-stage removal of residual intracanalicular acoustic neuroma and hemihypoglossal-intratemporal facial nerve anastomosis: technical note.

OBJECTIVE AND IMPORTANCE: Incomplete removal of residual intracanalicular tumor and injury to the facial nerve are the main problems associated with surgery of large acoustic neuromas via the retromastoid suboccipital approach. In patients with residual or recurrent intracanalicular neuromas, the translabyrinthine approach is the preferred surgical route, allowing complete tumor removal; it may eventually also be used for exposure of the intratemporal portion of the facial nerve for a hemihypoglossal-facial nerve anastomosis when a postoperative facial palsy exists This one-stage procedure has not been described previously. CLINICAL PRESENTATION: Three patients with postoperative facial palsy and residual intracanalicular tumor after surgical removal of a large acoustic neuroma via the retromastoid suboccipital approach underwent reoperation via the translabyrinthine approach and one-stage removal of the residual tumor and hemihypoglossal-facial nerve anastomosis. All three patients had a complete facial palsy of House-Brackmann Grade VI and a residual tumor of 8 to 12 mm. TECHNIQUE: A classic translabyrinthine approach was used to open the internal auditory canal and remove the residual intracanalicular tumor. The facial nerve was exposed in its mastoid and tympanic parts, mobilized, and transected; then, the long nerve stump was transposed into the neck and used for an end-to-side anastomosis into the hypoglossal nerve. The operation resulted in variable improvement of the facial muscle function up to Grade III (one patient) and Grade IV (two patients). CONCLUSION: Reoperation via the translabyrinthine approach is indicated for removal of residual intracanalicular acoustic neuroma and realization of a hypoglossal-facial nerve anastomosis in a single procedure. It is suggested that this type of anastomosis may also be used during the initial operation for acoustic neuroma removal when the facial nerve is inadvertently sectioned.

Anastomosis, Surgical↗