Management of Trauma of the Facial Nerve

Neuropeptides Involved in Facial Nerve Regeneration

Neuropeptides and neurotransmitters act as intermediaries to transmit impulses from one neuron to another via a synapse. These neuropeptides are also related to nerve degeneration and regeneration during nerve damage. Although there are various neuropeptides, three are associated with neural regeneration in facial nerve damage: calcitonin gene-related peptide (CGRP), galanin, and pituitary adenylyl cyclase-activating peptide (PACAP). Alpha CGRP in facial motoneurons is a signaling factor involved in neuroglial and neuromuscular interactions during regeneration. Thus, it may be a marker for facial nerve regeneration. Galanin is a marker of injured axons rather than nerve regeneration. PACAP has various effects on nerve regeneration by regulating the surrounding cells and providing neurotrophic factors. Thus, it may also be used as a marker for facial nerve regeneration. However, the precise roles of these substances in nerve generation are not yet fully understood. Animal studies have demonstrated that they may act as neuromodulators to promote neurotrophic factors involved in nerve regeneration as they appear early, before changes in the injured cells and their environment. Therefore, they may be markers of nerve regeneration.

Stab injury to the preauricular region with laceration of the external carotid artery without involvement of the facial nerve: a case report

Background

Open injuries to the face involving the external carotid artery are uncommon. These injuries are normally associated with laceration of the facial nerve because this nerve is more superficial than the external carotid artery. Hence, external carotid artery lesions are usually associated with facial nerve dysfunction. We present an unusual case report in which the patient had an injury to this artery with no facial nerve compromise.

Case presentation

A 25-year-old Portuguese man sustained a stab wound injury to his right preauricular region with a broken glass. Immediate profuse bleeding ensued. Provisory tamponade of the wound was achieved at the place of aggression by two off-duty doctors. He was initially transferred to a district hospital, where a large arterial bleeding was observed and a temporary compressive dressing was applied. Subsequently, the patient was transferred to a tertiary hospital. At admission in the emergency room, he presented a pulsating lesion in the right preauricular region and slight weakness in the territory of the inferior buccal branch of the facial nerve. The physical examination suggested an arterial lesion superficial to the facial nerve. However, in the operating theater, a section of the posterior and lateral flanks of the external carotid artery inside the parotid gland was identified. No lesion of the facial nerve was observed, and the external carotid artery was repaired. To better understand the anatomical rationale of this uncommon clinical case, we dissected the preauricular region of six cadavers previously injected with colored latex solutions in the vascular system. A small triangular space between the two main branches of division of the facial nerve in which the external carotid artery was not covered by the facial nerve was observed bilaterally in all cases.

Conclusions

This clinical case illustrates that, in a preauricular wound, the external carotid artery can be injured without facial nerve damage. However, no similar description was found in the reviewed literature, which suggests that this must be a very rare occurrence. According to the dissection study performed, this is due to the existence of a triangular space between the cervicofacial and temporofacial nerve trunks in which the external carotid artery is not covered by the facial nerve or its branches.

Outcome of different facial nerve reconstruction techniques

Introduction

There is no technique of facial nerve reconstruction that guarantees facial function recovery up to grade III.

Objective

To evaluate the efficacy and safety of different facial nerve reconstruction techniques.

Methods

Facial nerve reconstruction was performed in 22 patients (facial nerve interpositional graft in 11 patients and hypoglossal-facial nerve transfer in another 11 patients). All patients had facial function House-Brackmann (HB) grade VI, either caused by trauma or after resection of a tumor. All patients were submitted to a primary nerve reconstruction except 7 patients, where late reconstruction was performed two weeks to four months after the initial surgery. The follow-up period was at least two years.

Results

For facial nerve interpositional graft technique, we achieved facial function HB grade III in eight patients and grade IV in three patients. Synkinesis was found in eight patients, and facial contracture with synkinesis was found in two patients. In regards to hypoglossal-facial nerve transfer using different modifications, we achieved facial function HB grade III in nine patients and grade IV in two patients. Facial contracture, synkinesis and tongue atrophy were found in three patients, and synkinesis was found in five patients. However, those who had primary direct facial-hypoglossal end-to-side anastomosis showed the best result without any neurological deficit.

Conclusion

Among various reanimation techniques, when indicated, direct end-to-side facial-hypoglossal anastomosis through epineural suturing is the most effective technique with excellent outcomes for facial reanimation and preservation of tongue movement, particularly when performed as a primary technique.

Reconstruction of the paralyzed face

Facial nerve paralysis can be difficult to treat because it presents a variety of functional, aesthetic, and psychosocial challenges. The goals of treatment include facial symmetry at rest, corneal protection, oral competence, restoration of voluntary and spontaneous facial movements, and minimal synkinesis. A multitude of static and dynamic procedures have been used to achieve these goals. Facial nerve reapproximation or interpositional grafting is associated with the best end results. The results of dynamic procedures are generally better than those of static procedures. Optimal reconstruction of the paralyzed face usually requires multiple surgeries with both types of procedures. Patients must be extensively counseled regarding expected results before they embark on what is an oftentimes lengthy reconstructive process. In this article, we discuss the anatomy of the facial nerve, the etiologic factors associated with facial nerve paralysis, the evaluation of the patient with facial paralysis, and the various surgical options for static and dynamic reconstruction of the paralyzed face. We also review the literature.

Facial nerve paralysis

Emotions are communicated through facial expression. Happiness, confusion, and frustration can be expressed with a slight smile, eyebrow shift, or wrinkled nose. Injury to the facial nerve and subsequent inability of perform volitional mimetic movement can provoke anxiety. This article explores the causes, treatment, and prevention of facial nerve paralysis.

Surgical anatomy of tympano-mastoid segment of facial nerve

OBJECTIVE

Facial nerve is known to have a considerable variations more so in the temporal bone. An otologist with inadequate familiarity with facial nerve usually have a tendency to do incomplete surgery in chronic suppurative otitis media. The present study was conducted to explore the microanatomy of tympanic and mastoid segments of facial nerve.

SETTING

Temporal bone lab.

MATERIALS AND METHODS

This study was conducted at PGIMS Rohtak in 25 wet temporal bones which were dissected under the microscope. Various parameters studied included the length of tympanic and mastoid segments of facial nerve, various anomalies, depth from the cortex and relation to various important structures.

RESULTS

The mean length of tympanic segment was 11.1 mm±0.88 and mastoid segment was 15.4 mm±2.4. The angle at second genu was 95-125° and the facial canal was dehiscent in 12% cases.

CONCLUSIONS

The tympanomastoid segment of facial nerve has variations in length and in its relation with various middle ear structures. Further the nerve, in Indians is also at variance as compared to Japanese and Americans probably because of different racial configuration of the skull.

Iatrogenic complications from chronic ear surgery

Iatrogenic complications can and do occur in ear surgery. Whether the surgery is undertaken to treat chronic infectious disease or for other purposes (eg, for cochlear implants, shunts, or skull base approaches), the key to avoiding iatrogenic injuries and untoward events is attention to detail. Knowledge of what to do when the unexpected happens is the key to minimizing any negative outcome for the patient.

Secondary end-to-end repair of extensive facial nerve defects: Surgical technique and postoperative functional results

BACKGROUND

Repair of the transected facial nerve is imperative for restoration of muscle function, including the ability to produce appropriate facial expressions. Injury might involve the main trunk and its several branches. Restoration of function presupposes meticulous repair of all injured nerve branches.

METHODS

Here we report three cases of secondary tension-free end-to-end coaptation of a transected trunk and branches of the facial nerve by removal of the superficial part of the parotid gland.

RESULTS

Facial tone and symmetry at rest and motion were achieved. In two patients, a slight residual synkinesis is observed under stress.

CONCLUSIONS

Direct end-to-end coaptation of the facial nerve and its branches by the technique described should be considered before deciding on grafts or rerouting procedures to deal with gaps of up to 15 mm. This technique is not recommended in the presence of infection and nerve defects. Intensive postoperative physiotherapy is required for optimal results.

Direct coaptation of extensive facial nerve defects after removal of the superficial part of the parotid gland: an anatomic study

BACKGROUND

In the surgical repair of facial nerve paralysis, a tension-free end-to-end coaptation of the trunk or its branches with or without rerouting is functionally superior to grafting. Assuming that a lengthening of all branches of the parotid plexus can be attained by removal of the superficial part of the parotid gland and mobilization of the branches, we performed an anatomic study.

METHODS

The parotid regions of 10 cadavers were dissected to investigate the length gained for the branches of the parotid plexus by this technique. Every branch at the upper and ventral border of the gland was marked by a surgical suture. After removing the superficial part of the parotid gland, the branches were cut at the suture, and the proximal stump was drawn toward the distal stump. The distance of the overlapping stumps was measured by means of an electronic gliding caliper. In addition, in five specimens only the trunk of the facial nerve was dissected by the same method, and the distance of the overlapping stumps was measured.

RESULTS AND CONCLUSIONS

The results demonstrate that removing the superficial part of the parotid gland may be sufficient to enable direct coaptation without nerve grafting. Cut temporal or zygomatic branches with a gap of up to 15 mm and cut buccal or marginal mandibular branches with a gap of up to 23 mm can be bridged by mobilization of just the proximal stumps. This technique may also be used to bridge a 17-mm gap of the trunk of the facial nerve.

Hypoglossal-facial crossover in facial-nerve palsy: pure end-to-sideanastomosis technique

Hypoglossal-facial crossover is the most popular method of reconstructing the facial nerve in facial palsy resulting from proximal facial-nerve injury near the brainstem. Conventional hypoglossal-facial crossover involves performing a partial hypoglossal-nerve section or incision and an interpositional nerve graft to bridge the gap between the two nerves, which sometimes results in hemiglossal atrophy and its sequelae. Furthermore, the nerve graft may delay recovery and make facial reanimation weak. To solve these problems, we attempted to perform 'pure end-to-side anastomosis' (without section of the hypoglossal nerve) between the hypoglossal and facial nerves in four patients with facial palsy. In two patients (group I) a sural-nerve graft was used to bridge the gap between the two nerves. In the other two patients (group II) the intratemporal facial nerve was mobilised to the neck and one tension-free end-to-side anastomosis was performed. Facial symmetry and tone at rest were restored in all cases. Facial reanimation was achieved in group II after 8 months. Despite the small number of cases, we believe that the technique of hypoglossal-facial crossover with 'pure end-to-side anastomosis' and mobilisation of the intratemporal facial nerve can decrease donor-nerve morbidity in facial-nerve rehabilitation.

Skull base reconstruction and rehabilitation

This article separates skull base reconstruction into the surgical procedures available for immediate reconstruction of a small base defect and the secondary rehabilitative procedures that may be performed at a later date, usually for functional or cosmetic needs.

Management of facial paralysis resulting from temporal bone fractures: Our experience in 115 cases

OBJECTIVE

The goal of this study was to review decision factors and overall results regarding surgical and nonsurgical management of post-traumatic facial nerve paralysis (FP).

STUDY DESIGN

A retrospective study and literature review were performed.

METHODS

Between 1984 and 1990, 115 cases of post-traumatic FP were handled. Patients were evaluated through clinical, audiologic, radiologic, and electromyogram assessment. Depending on examination results, patients were treated either medically or surgically through total facial nerve decompression.

RESULTS

Forty-nine of the 50 medically treated patients experienced a normal or subnormal facial function recovery (grade I-II). Of the 65 (56.5%) surgically treated patients, 52 (80%) had immediate, 2 had delayed, and 11 (17%) had unknown delay-associated FP. The approaches chosen were middle fossa and transmastoid (75.3%), translabyrinthine (10.7%), or pure transmastoid according to facial nerve nonmotor branch evaluation, hearing, location of the fracture line, and the patient's general condition. Lesions were predominantly found in the geniculate ganglion area (66.2%). A nerve gap was found in only 13.8% of the cases. At 2 years after surgery, 93.8% had a grade I to III recovery. None had grade V or VI.

CONCLUSION

The rarity of severe nerve lesions encountered in surgically treated patients raises the question of better selection of candidates for surgery. Surgery is clearly indicated when FP is total, is of immediate onset, and is associated with a bad prognosis electromyogram pattern. In other settings, decisions are to be made based on high-resolution CT data and electromyogram results, thanks to a clinical survey and second electromyogram evaluation.

Complications and their management in tympanomastoid surgery

Chronic diseases of the ear and their surgical treatment can endanger the delicate structures of the temporal bone in close relationship with the middle ear. The experience and expertise of the otologic surgeon, based on perfect knowledge of the complex anatomy of the whole temporal bone, are unfortunately built up partly through the management of complications encountered in tympanomastoid surgery and may require knowledge of basic neuro-otologic procedures. Paralysis and paresis of the facial nerve and labyrinthine, and dural and vascular injuries may have consequences not only in the final result of surgery but also in endangering the patient's life. All major complications are discussed and some possible treatments are proposed. Minor complications affecting the temporomandibular joint, the dura, the external auditory canal, and the bony canal wall are also covered, along with some suggestions on how to keep these consequences within reasonable percentages.

Facial nerve rehabilitation after radical parotidectomy

OBJECTIVE

Examine functional outcomes in patients undergoing radical parotidectomy and facial nerve grafting. Identify factors that may affect rehabilitation in these patients.

STUDY DESIGN

Retrospective chart review and photographic analyses of 12 patients undergoing radical parotidectomy with interposition nerve grafts for facial nerve reconstruction.

METHODS

Data obtained for each patient regarding age, sex, histology of parotid neoplasm, cable graft source, administration of postoperative radiotherapy, and treatment for eye rehabilitation. Functional outcomes were assessed with the House-Brackmann grading system at 6 months, 1 year, and 2 years after surgery.

RESULTS

All nerve grafts were harvested from cervical plexus sensory nerves with microscopic epineural repair performed for all neurorrhaphies. Overall, 9 of 12 patients achieved a grade III 2 years after surgery. All patients under age 30 obtained a grade III. Of the seven patients receiving postoperative radiation, five achieved a grade III. Older patients often required surgical procedures to facilitate eye closure.

CONCLUSIONS

Facial nerve rehabilitation after radical parotidectomy can be successfully achieved with cervical plexus interposition nerve grafts. Postoperative radiotherapy did not appear to affect return of function, and younger patients consistently achieved good functional outcomes after nerve grafting. Older patients frequently require surgical procedures for eye rehabilitation after radical parotidectomy.

Pediatric temporal bone fractures

OBJECTIVE

To examine the etiology, presentation, and management of temporal bone fractures in children.

STUDY DESIGN

Case control.

METHOD

Retrospective review of a level I pediatric trauma center from July 1, 1990 to November 1, 1996 identified 680 patients. Inclusion criteria of age less than 14 years and only blunt temporal bone trauma identified 122 patients, with 97 charts available for review. The criteria for temporal bone fracture consisted of both clinical and radiologic information. Only patients with temporal bone fractures confirmed by computed tomography, a complete otolaryngology examination, and audiometric evaluations were included in the study. The data were analyzed with the Kruskal-Wallis analysis of variance (ANOVA) for examining the three separate age groups of fractures. Chi-squared analysis was used to compare these data with previously published adult and pediatric temporal bone fracture series and to examine the three separate age groups of fractures.

RESULTS

The review identified 72 children with 79 temporal bone fractures: 47 boys and 25 girls. The patients ranged from 6 months to 14 years of age, with a bimodal distribution of patients with peaks at 3 years and 12 years of age. The most common causes of fractures were motor vehicle accidents (47%), falls (40%), biking accidents (8%), and blows to the head (7%). Common presenting signs and symptoms included hearing loss (82%), hemotympanum (81%), loss of consciousness (63%), intracranial injuries (58%), bloody otorrhea (58%), extremity fractures (8%), and facial nerve weakness (3%). The most common causes of temporal bone fractures were falls and motor vehicle accidents. Forty-two patients were noted to have bloody otorrhea and possible cerebrospinal fluid leak. Twenty-four received intravenous antibiotics. No patient developed prolonged otorrhea or meningitis during hospitalization and the follow-up period. The classification of fracture patterns was longitudinal, 54%; transverse, 6%; oblique, 10%; squamous, 27%; and other, 3%. Hearing loss was found in 59 patients, with conductive hearing loss being the most common finding in 56% of the patients, followed by sensorineural hearing loss in 17% and mixed hearing loss in 10%.

CONCLUSIONS

Pediatric temporal bone fractures are associated with falls and motor vehicle accidents. There is a high incidence of associated intracranial injuries and hearing loss, but facial nerve injuries are uncommon. Timely management minimizes complications.

A new technique for hypoglossal-facial nerve repair

Hypoglossal reinnervation of the facial nerve may be required after a proximal facial nerve injury. The classic hypoglossal-facial graft procedure involves transection of the donor hypoglossal nerve, resulting in hemiglottic paralysis that, in association with paralysis of other cranial nerves, may cause speech and swallowing difficulties. Multiple lower cranial nerve palsies in conjunction with facial paralysis, as may occur after procedures such as skull base surgery, contraindicate the use of such techniques. The successful use of XII-VII "interposition jump grafts" without hemiglossal weakness has been described However, a prolonged recovery period and weaker facial reanimation have been seen. In order to attain maximum facial reinnervation while preserving hypoglossal function, we have developed a new technique of XII-VII repair. This method involves mobilization of the intratemporal portion of the facial nerve remnant, achieving a single anastomosis with the hypoglossal nerve, which has been partially incised. This technique has been used in three patients to date, with 6 to 11 months follow-up. In all cases facial tone and symmetry have been restored and voluntary facial expression accomplished. The authors conclude that by employing the techniques described highly satisfactory cosmetic and functional results may be expected, without compromising hypoglossal nerve function.

MR imaging of neuronal transport in the guinea pig facial nerve: initial findings

Certain dextran coated iron oxides such as MION (monocrystalline iron oxide nanocompound) coupled to wheat germ agglutinin (MION-WGA) have been shown to exhibit i) neuronal uptake ii) axonal transport and iii) strong magnetic effects on tissues (superparamagnetism) in which they are localized. In the current study, we utilized such an agent to visualize axonal transport in the facial nerve in vivo by magnetic resonance (MR) imaging. Following injection of the compound into the facial nerves of guinea pigs, MR images were obtained at multiple time points (1, 3 and 5 days) and the imaged tissues were processed for subsequent histological examination. In nerves that had been injected with MION-WGA, the entire nerve appeared as a uniformly hypointense structure with a calculated transport rate of 5 mm/day. By 3 days, the agent within the facial nerve was traceable by MRI from a site of injection in the buccal branch to the stylomastoid foramen. Fluorescence and autoradiography studies confirmed axonal transport. These results show that MION-based magnetopharmaceuticals can be used to demonstrate slow axonal transport, and thereby visualize functional peripheral nerves in vivo by MR imaging. The method holds promise for developmental neuroscience research as well as a method to detect neural abnormalities by MR imaging.

Management of traumatic facial nerve paralysis with carotid artery cavernous sinus fistula

Massive skull base injuries require detailed preoperative neurological and neurovascular assessment prior to undertaking surgical repair of isolated cranial nerve deficits. We present the management of a patient with traumatic facial paralysis, cerebrospinal fluid leak, and carotid artery cavernous sinus fistula as the result of a gunshot wound to the skull base. The carotid artery cavernous sinus fistula was ultimately controlled with super-selective embolization via the vertebral artery. The facial nerve injury was then safely treated with mobilization of the labyrinthine and vertical segments to allow a primary anastomosis.