Iatrogenic facial nerve injuries during chronic otitis media surgery: a multicentre retrospective study

Facial ridge management in canal wall down tympanoplasty for middle-ear cholesteatoma

OBJECTIVE

To estimate whether leaving a high facial ridge during canal wall down tympanoplasty increases the risk of residual cholesteatoma.

METHODS

In this retrospective case review, 321 patients treated with primary canal wall down tympanoplasty for middle-ear cholesteatoma were divided into a completely lowered facial ridge group and a non-completely lowered facial ridge group. Factors affecting facial ridge management, residual disease rate and disease-free survival were analysed.

RESULTS

Residual disease rates were 10.8 per cent in the non-completely lowered facial ridge group and 16.6 per cent in the completely lowered facial ridge group (p = 0.15). Localisation at sinus tympani, mesotympanum or supratubal recess, pre-operative extracranial complications, and destroyed ossicular chain or fixed platina were associated with a completely lowered facial ridge. Residual disease rates and disease-free survival did not significantly differ between the groups.

CONCLUSION

Facial ridge can be managed according to cholesteatoma extension. The facial ridge can be maintained high if the cholesteatoma does not involve sinus tympani, mesotympanum or supratubal recess, without increasing the risk of residual disease.

Surgical management and the prognosis of iatrogenic facial nerve injury in middle ear surgery: a 20-year experience

BACKGROUND

Iatrogenic facial nerve injury is one of the severest complications of middle ear surgery, this study aims to evaluate surgical management and prognosis in the era of improved surgical instruments.

METHODS

Patients suffered from facial nerve paralysis after middle ear surgery between January 2000 and December 2019 were retrospectively collected. Demographic characters, primary disease and surgery, details of revision surgery were analyzed.

RESULTS

Forty-five patients were collected, of whom 8 were injured at our center and 37 were transferred. For 8 patients injured at our center, seven (87.5%) ranked House-Brackmann (H-B) grade V and one (12.5%) ranked H-B VI before revision surgery; postoperatively, two (25.0%) patients recovered to H-B grade I, four (50.0%) recovered to H-B II, and the other two (25.0%) recovered to H-B III. For 37 patients transferred, thirteen (35.1%) ranked H-B grade V and 24 (64.9%) ranked H-B VI preoperatively, final postoperative grade ranked from H-B grade I to grade V, with H-B I 6 (16.2%) cases, H-B II 6 (16.2%) cases, H-B III 18 (48.6%) cases, H-B IV 5 (13.5%) cases and H-B V 2 (5.4%) cases. The most vulnerable site was tympanic segment (5, 62.5% and 27, 73.0% respectively). Twenty-one (46.7%) patients suffered from mild injury and 24 (53.3%) suffered from partial or complete nerve transection. For surgical management, twenty-one (46.7%) patients received decompression, nineteen (42.2%) received graft and 5 (11.1%) received anastomosis. Those decompressed within 2 months after paralysis had higher possibility of H-B grade I or II recovery (P = 0.026), those received graft within 6 months were more likely to get H-B grade III recovery (P = 0.041), and for patients underwent anastomosis within 6 months, all recovered to H-B grade III.

CONCLUSIONS

Tympanic segment is the vulnerable site. If facial nerve paralysis happens, high-resolution computed tomography could help identify the injured site. Timely treatment is important, decompression within 2 months after paralysis, graft and anastomosis within 6 months lead to better recovery.

Analysis of mastoid portion of facial nerve course in temporal bone using computed tomography

<b>Introduction:</b> The facial nerve (FN) follows a complex route in the temporal bone. Successful temporal bone surgery requires knowledge of its course which can be achieved using imaging methods such as computed tomography. This investigation aims to analyze the FN course in its mastoid portion and second genu and the frequency of its atypical course.</br></br> <b>Material and methods:</b> This is a retrospective study that enrolled 104 CT scans of temporal bones of patients followed up in the outpatient clinic of the Otorhinolaryngology Department of Dentistry Faculty of the Medical University of Warsaw between 2020 and 2022. FN courses were classified as straight, bulging, or letter "S"-like. Other parameters estimated: </br> • position of the second genu according to the prominence of the lateral semicircular canal (classified as lateral, medial, or middle) and its distance from a line adjacent to the lateral semicircular canal was measured;</br> • the distance between the short process of the incus and the outermost point of the second genu;</br> • the course of the mastoid portion of FN and the location of SG in comparison to the tympanic portion of n. VII. The course was later classified as lateral, medial, or middle.</br></br> <b>Results:</b> Among the 104 assessed temporal bones, the course of the mastoid portion of FN was classified as bulging in 47 cases (45.2%). Straight and letter "S"-like courses were present in 41 (39.4%) and 16 (15.4%) cases, respectively. Deviation of the second genu according to the prominence of the lateral semicircular canal was medial in 86 cases (82.7%), and middle in 4 cases (3.8%). In the rest, second genu was paramedian to the prominence of the later circular canal. The mean distance between the short process of the incus and the outermost point of SG was 4.9 mm (0.73 mm). The mastoid portion was located laterally, medially, and in the middle of the tympanic portion plane in, respectively, 4.8%, 83.7%, and 11.5%. The second genu was located laterally, medially, and in the middle of the tympanic portion plane in 1.9%, 73.1%, and 25%, respectively. In conclusion, seven temporal bones (6.7%) of five patients presented with a lateral displacement of FN in relation to the established anatomical landmarks.</br></br> <b>Conclusions:</b> Although the atypical course of FN, including the lateral displacement of the mastoid portion, is rare, screening for it is crucial before surgical exploration.

Measurement of rat and human tissue optical properties for improving the optical detection and visualization of peripheral nerves

Peripheral nerve damage frequently occurs in challenging surgical cases resulting in high costs and morbidity. Various optical techniques have proven effective in detecting and visually enhancing nerves, demonstrating their translational potential for assisting in nerve-sparing medical procedures. However, there is limited data characterizing the optical properties of nerves in comparison to surrounding tissues, thus limiting the optimization of optical nerve detection systems. To address this gap, the absorption and scattering properties of rat and human nerve, muscle, fat, and tendon were determined from 352-2500 nm. The optical properties highlighted an ideal region in the shortwave infrared for detecting embedded nerves, which remains a significant challenge for optical approaches. A 1000-1700 nm hyperspectral diffuse reflectance imaging system was used to confirm these results and identify optimal wavelengths for nerve imaging contrast in an in vivo rat model. Optimal nerve visualization contrast was achieved using 1190/1100 nm ratiometric imaging and was sustained for nerves embedded under ≥600 µm of fat and muscle. Overall, the results provide valuable insights for optimizing the optical contrast of nerves, including those embedded in tissue, which could lead to improved surgical guidance and nerve-sparing outcomes.

A novel imaging scoring method for identifying facial canal dehiscence: an ultra-high-resolution CT study

OBJECTIVES

Facial canal dehiscence (FCD), typically found in the tympanic segment, is a risk factor for facial nerve injury. An imaging scoring method was proposed to identify FCD based on ultra-high-resolution CT.

METHODS

Forty patients (21 females and 19 males, mean age 44.3 ± 17.4 years), whose tympanic facial canal (FC) was examined during otological surgery, were divided into the FCD group (n = 29) and the control group (n = 11) based on surgical findings. Imaging appearance of tympanic FC was scored 0-3: 0 = no evident bony covering, 1 = discontinuous bony covering with linear deficiency, 2 = discontinuous bony covering with dotted deficiency, and 3 = continuous bony covering. Both lateral and inferior walls were assigned a score as L_FCD and I_FCD, respectively. An FCD score was calculated as L_FCD + I_FCD. The diagnostic value of the FCD score was tested using the ROC curve.

RESULTS

The inter-observer agreement was moderate for the lateral wall (Cohen's κ coefficient 0.416, 95% CI 0.193-0.639), and good for the inferior wall (Cohen's κ coefficient 0.702, 95% CI 0.516-0.888). In the FCD group, the most common appearance for both walls was discontinuous bony covering with linear deficiency (L_FCD = 1, 22/29, 75.9%; I_FCD = 1, 15/29, 51.7%). An FCD score of less than 4 was associated with high sensitivity (0.82) and specificity (0.93) for identifying FCD, with an AUC of 0.928.

CONCLUSIONS

Using the proposed scoring method, FCD score < 4 could identify FCD of the tympanic segment with high concordance with surgical findings.

KEY POINTS

• Imaging appearance of the tympanic facial canal (FC) is divided into four types based on ultra-high-resolution CT images. • The most common appearance of FC with facial canal dehiscence (FCD) is discontinuous bony covering with linear deficiency. • An FCD score, consisting of scores of the lateral and inferior walls, less than 4 is highly indicative of FCD.

Iatrogenic facial nerve injury in mastoidectomy: The impact of variables on the outcome

OBJECTIVE

To evaluate iatrogenic facial nerve injury in mastoidectomy and its paralysis improvement result after nerve injury management.

METHODS

A retrospective review of medical records of 21 patients with iatrogenic facial nerve injury following mastoidectomy who underwent nerve injury management in a tertiary referral center.

RESULTS

There were nine males and 12 females, with a mean age of 40.4 ± 15.1 years. Cholesteatoma was the most common primary pathology (76.2%). Mastoidectomy was canal wall up in 8 patients and canal wall down in 13. Nerve injury was due to drilling in 10 patients and sharp tools in 11. The tympanic segment of the facial nerve was the most common injured site (50.0%). Decompression was the most common nerve injury management method (52.4%). Other injury management methods were end-to-end anastomosis (14.3%), great auricular nerve graft (23.8%), and facial-hypoglossal nerve transfer (9.5%). No statistically significant correlation was found between facial nerve function 3-6 months after injury management and the following factors: age, gender, primary pathology, type of mastoidectomy, surgeon's experience, nerve injury site, mechanism of trauma, and nerve injury management method and timing.

CONCLUSION

Regardless of the surgeon's experience or technique applied, a meticulous approach may be more valuable in decreasing the chance of iatrogenic facial nerve injury.

Facial Nerve Repair following Acute Nerve Injury

Background  Acute facial nerve iatrogenic or traumatic injury warrants rapid management with the goal of reestablishing nerve continuity within 72 hours. However, reconstructive efforts should be performed up to 12 months from the time of injury since facial musculature may still be viable and thus facial tone and function may be salvaged.

Methods  Data of all patients who underwent facial nerve repair following iatrogenic or traumatic injury were retrospectively collected and assessed. Paralysis etiology, demographics, operative data, postoperative course, and outcome were examined.

Results  Twenty patients underwent facial nerve repair during the years 2004 to 2019. Data were available for 16 of them. Iatrogenic injury was the common category ( n  = 13, 81%) with parotidectomy due to primary parotid gland malignancy being the common surgery ( n  = 7, 44%). Nerve repair was most commonly performed during the first 72 hours of injury ( n  = 12, 75%) and most of the patients underwent nerve graft repair ( n  = 15, 94%). Outcome was available for 12 patients, all of which remained with some degree of facial paresis. Six patients suffered from complete facial paralysis (50%) and three underwent secondary facial reanimation (25%). There were no major operative or postoperative complications.

Conclusion  Iatrogenic and traumatic facial nerve injuries are common etiologies of acquired facial paralysis. In such cases, immediate repair should be performed. For patients presenting with facial paralysis following previous surgery or trauma, nerve repair should be considered up to at least 6 months of injury. Longstanding paralysis is best treated with standard facial reanimation procedures.

Improved Nerve Visualization in Head and Neck Surgery Using Mueller Polarimetric Imaging: Preclinical Feasibility Study in a Swine Model

BACKGROUND AND OBJECTIVES

Meticulous dissection and identification of nerves during head and neck surgery are crucial for preventing nerve damage. At present, nerve identification relies heavily on the surgeon's knowledge of anatomy, optionally combined with intraoperative neuromonitoring. Recently, optical techniques such as Mueller polarimetric imaging (MPI) have shown potential to improve nerve identification.

STUDY DESIGN/MATERIALS AND METHODS

With institutional approval, seven 25-35 kg Yorkshire pigs underwent cervical incision in the central neck. Intraoperative images were obtained using our in-house MPI system. Birefringence maps from the MPI system were processed to quantify the values between 0 and 255 from different tissue types; an active contour model was applied to further improve nerve visualization on the corresponding color images.

RESULTS

Among the seven pigs, the vagus nerves and recurrent laryngeal nerves were successfully differentiated with a mean intensity of 130.954 ± 20.611, which was significantly different (P < 0.05) from those of arteries (78.512 ± 27.78) and other surrounding tissues (82.583 ± 35.547). There were no imaging-related complications during the procedure. © 2021 Wiley Periodicals LLC.

CONCLUSIONS

MPI is a potentially complementary intraoperative tool for nerve identification in adjacent tissues.

Prevalence of facial canal dehiscence and other bone defects by computed tomography

INTRODUCTION

The facial nerve is the most vulnerable structure during otological surgeries. Facial canal dehiscence (FCD) is the main risk factor for iatrogenic injuries. Its prevalence in clinical studies ranges between 6 and 33.3%, while anatomical studies report 25-57%. The objective was to determine the prevalence of FCD stratified by age and gender in a healthy population.

MATERIALS AND METHODS

Temporal bones from high-resolution computed tomography (CT) were analyzed. Patients with a history of trauma or tumors of the temporal bone, cholesteatomas, chronic middle ear disease, and any pathology that could modify the bone's anatomy, were excluded.

RESULTS

A total of 184 temporal bones were included. FCD was observed in 94 (51.2%) of the analyzed bones. The tympanic portion was the most frequently affected site with 91 (49.5%), followed by the mastoid segment with 3 (1.6%). No dehiscence was found in the labyrinth portion. We observed 30 (31.9%) of the FCD involved the oval window. Other bone defects identified with the FCD included: 11 (11.7%) with a lateral semicircular canal fistula and 7 (7.4%) with tegmen tympani erosions.

CONCLUSION

FCD has a high prevalence among healthy patients. A pre-surgical otological evaluation using high-resolution CT should be indicated to properly assess the patient and reduce the risk of injury.

Comparison between VII-to-VII and XII-to-VII coaptation techniques for early facial nerve reanimation after surgical intra-cranial injuries: a systematic review and pooled analysis of the functional outcomes

The surgical injury of the intracranial portion of the facial nerve (FN) is a severe complication of many skull base procedures, and it represents a relevant issue in terms of patients' discomfort, social interactions, risk for depression, and social costs. The aim of this study was to investigate the surgical and functional outcomes of the most common facial nerve rehabilitation techniques. The present study is a systematic review of the pertinent literature, according to the PRISMA guidelines. Two different online medical databases (PubMed, Scopus) were screened for studies reporting the functional outcome, measured by the House-Brackman (HB) scale, and complications, in FN early reanimation, following surgical injuries on its intracranial portion. Data on the VII-to-VII and XII-to-VII coaptation, the surgical technique, the use of a nerve graft, the duration of the deficit, and complications were collected and pooled. The XII-to-VII end-to-side coaptation seems to provide higher chances for functional restoration (HB 1-3) than the VII-to-VII (68.8% vs 60.6%), regardless of the duration of the palsy deficit, the use or not of a nerve graft, and the use of stitches or glues. However, its complication rate was as high as 28.6%, and a second procedure is then often needed. The XII-to-VII side-to-end coaptation is the most effective in providing a functional outcome (HB 1-3), even though it is associated to a higher complication rate. Further trials are needed to better investigate this relevant topic, in terms of health-related social costs and patients' quality of life.

Percutaneous Threshold of Facial Nerve Stimulation Predicts Facial Canal Dehiscence

Iatrogenic facial nerve (FN) injury is one of the most feared complications of otologic surgery. Dehiscence of the bony covering of the FN within the temporal bone increases FN vulnerability to accidental injury. High-resolution computed tomography (HRCT) of the temporal bone is used preoperatively to assess middle ear and mastoid anatomy; however, it is unreliable for detecting facial canal dehiscence. In this study, our aim was to determine if preoperative percutaneous FN stimulation could predict middle ear facial canal dehiscence. Between January 2015 and February 2017, we performed preoperative HRCT and percutaneous FN stimulation on adult patients who underwent otologic surgery at our institution. Stimulation was performed with a monopolar probe placed on the skin over the stylomastoid foramen. Electrical stimuli ranged from 0 to 40 milliamperes (mA). Recordings were made from ipsilateral facial muscles. Dependent variables included threshold to compound muscle action potential (CMAP), threshold to maximum amplitude of CMAP, and maximum amplitude of CMAP for each muscle. A retrospective chart review was performed. Seventy patients met inclusion criteria. Of the 24 with an intraoperatively confirmed dehiscence, 10 were identified preoperatively by the attending surgeon on HRCT. Averages of the lowest recorded threshold to CMAP (5.1mA v. 9.1mA), and an average of the threshold to CMAP (8.9 mA. 11.8 mA) of dehiscent versus non-dehiscent nerves were significantly different (p < .05). In conclusion, percutaneous FN stimulation is a simple and cost-effective tool that can give the surgeon important preoperative information about FN anatomy.

Facial canal dehiscence in patients with cholesteatoma: concordance between intraoperative inspection, computed tomography and neurophysiological findings

OBJECTIVES

To assess the diagnostic capacity of intraoperative neurophysiological monitoring with respect to "gold standard" microscopic findings of facial canal dehiscence in middle ear cholesteatoma surgery.

STUDY DESIGN, PATIENTS AND SETTING

We carried out a retrospective cohort study of 57 surgical interventions for cholesteatoma between 2008 and 2013 at Hospital Universitario de Canarias, Spain.

DIAGNOSTIC INTERVENTIONS

Each patient underwent preoperative computed tomography (CT), intraoperative neurophysiological monitoring and intraoperative inspection of the facial nerve during microsurgery. Diagnostic concordance on the presence/absence of facial canal dehiscence was assessed in 54 surgical interventions.

MAIN OUTCOME

Presence of facial canal dehiscence.

RESULTS

Of 57 interventions, 39 were primary surgeries; 11 (28.2%) showed facial canal dehiscence. and 18 were revision surgeries; 6 (33.3%) showed facial canal dehiscence. The facial nerve was not damaged in any patient. Facial canal dehiscence was observed in 17 (29.82%) interventions. We used intraoperative microscopic findings as the gold standard. Neurophysiological study showed a sensitivity of 94.1, specificity 97.3, positive predictive value (PPV) 57.8 and negative predictive value of 97.2. CT showed a sensitivity of 64.7, specificity 78.4, PPV 57.8 and negative predictive value of 82.

CONCLUSIONS

Our neurophysiological study showed greater sensitivity and higher PPV than CT for the detection of facial canal dehiscence. We found no relationship between disease progression time and the presence of facial canal dehiscence.

Olfactory ensheathing cells promote nerve regeneration and functional recovery after facial nerve defects

Olfactory ensheathing cells from the olfactory bulb and olfactory mucosa have been found to increase axonal sprouting and pathfinding and promote the recovery of vibrissae motor performance in facial nerve transection injured rats. However, it is not yet clear whether olfactory ensheathing cells promote the reparation of facial nerve defects in rats. In this study, a collagen sponge and silicone tube neural conduit was implanted into the 6-mm defect of the buccal branch of the facial nerve in adult rats. Olfactory ensheathing cells isolated from the olfactory bulb of newborn Sprague-Dawley rats were injected into the neural conduits connecting the ends of the broken nerves, the morphology and function of the regenerated nerves were compared between the rats implanted with olfactory ensheathing cells with the rats injected with saline. Facial paralysis was assessed. Nerve electrography was used to measure facial nerve-induced action potentials. Visual inspection, anatomical microscopy and hematoxylin-eosin staining were used to assess the histomorphology around the transplanted neural conduit and the morphology of the regenerated nerve. Using fluorogold retrograde tracing, toluidine blue staining and lead uranyl acetate staining, we also measured the number of neurons in the anterior exterior lateral facial nerve motor nucleus, the number of myelinated nerve fibers, and nerve fiber diameter and myelin sheath thickness, respectively. After surgery, olfactory ensheathing cells decreased facial paralysis and the latency of the facial nerve-induced action potentials. There were no differences in the general morphology of the regenerating nerves between the rats implanted with olfactory ensheathing cells and the rats injected with saline. Between-group results showed that olfactory ensheathing cell treatment increased the number of regenerated neurons, improved nerve fiber morphology, and increased the number of myelinated nerve fibers, nerve fiber diameter, and myelin sheath thickness. In conclusion, implantation of olfactory ensheathing cells can promote regeneration and functional recovery after facial nerve damage in rats.