The Validity of the Koos Classification System With Respect to Facial Nerve Function.

BACKGROUND: The Koos classification of vestibular schwannomas is designed to stratify tumors based on extrameatal extension and compression of the brainstem. Our prior study demonstrated excellent reliability. No study has yet assessed its validity. OBJECTIVE: To present a retrospective study designed to assess the validity of the Koos grading system with respect to facial nerve function following treatment of 81 acoustic schwannomas. METHODS: We collected data retrospectively from 81 patients with acoustic schwannomas of various Koos grades who were treated with microsurgical resection or stereotactic radiosurgery. House-Brackmann (HB) scores were used to assess facial nerve function and obtained at various time points following treatment. We generated Spearman's rho and Kendall's tau correlation coefficients along with a logistic regression curve. RESULTS: We found no significant difference in the presence or absence of facial dysfunction by Koos classification when looking at all patients. There was a positive but fairly weak correlation between HB score and Koos classification, which was only significant at the first postoperative clinic appointment. There was a statistically significant difference in the presence or absence of facial dysfunction between patients treated with surgery vs radiation, which we expected. We found no statistically significant difference when comparing surgical approaches. Logistic regression modeling demonstrated a poor ability of the Koos grading system to predict facial nerve dysfunction following treatment. CONCLUSION: The Koos grading system did not predict the presence of absence of facial nerve dysfunction in our study population. There were trends within subgroups that require further exploration.

Amer's classification of territories of facial nerve injury in early cases and strategies for the management of different territories.

Early cases of facial nerve injury are best treated by restoring the neural pathway to the same existing facial muscles. Knowledge of the exact territory of facial nerve injury is required to design a plane for the reconstruction of these injuries and to compare results. The current study aims to design a classification system for territories of facial nerve injury based on the location of nearest healthy fascicles to the site of injury both proximally and distally. Two hundred-one patients with early facial nerve injury were assessed for treatment. According to the results of the exploration, 13 territories of injury were identified. The management strategy was planned according to the territory of injury. The current classification system is a simple, easy and effective method for the classification of territories of facial nerve injury. The classification system accurately describes the nearest possible healthy proximal and distal fascicles and can be employed to easily report cases and implement a management plan. This classification scheme also allows us to more effectively compare results.

Dynamic rehabilitation of facial nerve injury: a review of the literature.

INTRODUCTION: Given the morbidity caused by facial nerve paralysis, there have been consistent approaches to treatment over the past 20 years in reanimation of the facial nerve. Treatment depends on accurate clinical examination, a good understanding of the anatomic course, and appropriate diagnostic tests. There are various options when it comes to dynamic facial nerve reanimation that range from nerve grafting, nerve anastomosis, crossover techniques and muscle transfer to microneurovascular muscle flaps, and-recently-potentially new concepts with microelectromechanical systems (MEMS) technology. The various dynamic facial nerve treatment modalities are discussed. METHODS AND RESULTS: A comprehensive review of the literature was performed detailing various techniques used for dynamic rehabilitation following facial nerve injury and their known results and complications. CONCLUSIONS: Currently, techniques have been attempted to achieve adequate dynamic facial reanimation of the paralyzed facial nerve. Despite the advances that have occurred in the last few years, it has been classically very difficult to achieve a House-Brackmann grade better than grade III. Outcomes are improving. Ultimately, the approach depends on the surgeon's experience.

[Changes in facial nerve function, morphology and neurotrophic factor III expression following three types of facial nerve injury].

OBJECTIVE: To study the changes in facial nerve function, morphology and neurotrophic factor III (NT-3) expression following three types of facial nerve injury. METHOD: Changes in facial nerve function (in terms of blink reflex (BF), vibrissae movement (VM) and position of nasal tip) were assessed in 45 rats in response to three types of facial nerve injury: partial section of the extratemporal segment (group one), partial section of the facial canal segment (group two) and complete transection of the facial canal segment lesion (group three). All facial nerves specimen were then cut into two parts at the site of the lesion after being taken from the lesion site on 1st, 7th, 21st post-surgery-days (PSD). Changes of morphology and NT-3 expression were evaluated using the improved trichrome stain and immunohistochemistry techniques ,respectively. RESULT: Changes in facial nerve function: In group 1, all animals had no blink reflex (BF) and weak vibrissae movement (VM) at the 1st PSD; The blink reflex in 80% of the rats recovered partly and the vibrissae movement in 40% of the rats returned to normal at the 7th PSD; The facial nerve function in 600 of the rats was almost normal at the 21st PSD. In group 2, all left facial nerve paralyzed at the 1st PSD; The blink reflex partly recovered in 40% of the rats and the vibrissae movement was weak in 80% of the rats at the 7th PSD; 8000 of the rats'BF were almost normal and 40% of the rats' VM completely recovered at the 21st PSD. In group 3, The recovery couldn't happen at anytime. Changes in morphology: In group 1, the size of nerve fiber differed in facial canal segment and some of myelin sheath and axons degenerated at the 7th PSD; The fibres' degeneration turned into regeneration at the 21st PSD; In group 2, the morphologic changes in this group were familiar with the group 1 while the degenerated fibers were more and dispersed in transection at the 7th PSD; Regeneration of nerve fibers happened at the 21st PSD. In group 3, most of the fibers crumbled at the 7th PSD and no regeneration was seen at the 21st PSD. Changes in NT-3: Positive staining of NT-3 was largely observed in axons at the 7th PSD, although little NT-3 was seen in the normal fibers. CONCLUSION: Facial palsy of the rats in group 2 was more extensive than that in group 1 and their function partly recovers at the 21st PSD. The fibres' degeneration occurs not only dispersed throughout the injury site but also occurred throught the length of the nerve. NT-3 immunoreactivity increased in activated fibers after partial transection.

Comparison of facial nerve injury and recovery rates after antegrade and retrograde nerve dissection in parotid surgery for benign disease: prospective study over 4 years.

The facial nerve can be dissected using an antegrade or retrograde approach. Antegrade dissection is the established technique and retrograde dissection is used less often. Recent publications have drawn attention to the potential value of the retrograde technique particularly if direct identification of the nerve trunk is difficult, and in revision procedures. We prospectively studied 43 consecutive procedures in 40 patients who had parotidectomy over a 4-year period, and evaluated and compared rates of temporary and permanent nerve injury, and nerve recovery after antegrade and retrograde dissection in operations for benign parotid disease. Each patient was allocated randomly to the antegrade (n=20) or retrograde (n=20) groups. Three patients were excluded. All patients had peroperative nerve monitoring and were followed up at 1 week, 1 month, 3 months, or to full recovery of the nerve. The House-Brackmann (HB) grading system was used to assess the degree of injury to the nerve. A high rate of serious nerve injury (HBIII or above) was associated with retrograde dissection at 1 week. Serious nerve injuries (HBIII or above) were slow to recover after the antegrade technique at 3 months. There was no difference between groups in the rates of full nerve recovery at 6 months.

Prospective study of facial nerve function after surgical procedures for the treatment of temporomandibular pathology.

PURPOSE: The aim of this prospective study was to report facial nerve injury following surgical procedures for the treatment of temporomandibular pathology, using the House-Brackmann facial nerve grading system (HBFNGS) as a means of classifying and measuring the degree and type of injury. PATIENTS AND METHODS: The sample consisted of 32 patients who underwent temporomandibular joint (TMJ) surgery. A total of 50 approaches were carried out. Surgical procedures consisted of TMJ reconstruction, gap arthroplasty, eminectomy, bone plates for the treatment of chronic mandibular luxation, and disc plication. Facial nerve function of all patients was evaluated preoperatively and 24 hours after surgery. Patients who presented postoperative facial nerve injury were likewise examined using the HBFNGS at 24 hours, 1 week, 1 month, and 3 months. RESULTS: Of the 32 patients, 12.5% (ie, 8% of the 50 approaches) showed signs of facial nerve injury after TMJ surgery. The prevalence of postoperative facial nerve injury was significantly greater in the patients who had ankylosis (P = .014) and in those submitted to gap arthroplasty (P = .011). At 24 hours, none of the patients showed total nerve paralysis or severe dysfunction, only a moderately severe dysfunction (50%), or moderate dysfunction (50%). The forehead was the most affected area measured. At 3 months, all patients had recovered their normal facial nerve function. The overall improvement in facial nerve function was 40% for the patients classified initially with moderately severe dysfunction and 60% for those with moderate dysfunction. CONCLUSION: The frequency of facial nerve injury was related to the diagnosis of the temporomandibular pathology and surgical procedures. Facial nerve impairment was shown to be of a temporary nature. Moreover, there is a need to standardize the reporting of facial nerve recovery.

Traumatic facial nerve injuries: review of diagnosis and treatment.

Both blunt and penetrating craniofacial trauma may lead to severe facial nerve injury and sequelae of facial paralysis. Initial evaluation involves quantitation of motor deficits using a clinical grading system, such as the House-Brackmann scale. High resolution computed tomography is used for localization of nerve injury in suspected cases of temporal bone trauma. In the absence of gross radiographic abnormalities, electrophysiologic testing helps predict the likelihood of spontaneous recovery. In patients with deteriorating facial nerve injuries by electroneuronography, surgical exploration is the preferred management. Primary end-to-end neurorrhaphy is the preferred management for transection injuries, while facial nerve decompression may benefit other forms of high-grade nerve trauma. Secondary facial reanimation procedures, such as cranial nerve crossovers, dynamic muscle slings or various static procedures, are useful adjuncts when initial facial nerve repair is unsuccessful or impossible. A review of facial nerve trauma management and case illustrations are presented.