Discerning a smile - The intricacies of analysis of post-neck dissection asymmetry

Effectiveness of Intraoperative Facial Nerve Monitoring in Submandibular Gland Surgery: A Retrospective Study of a Single Institution

BACKGROUND

Intraoperative facial nerve monitoring (IFNM) is becoming increasingly prevalent as an established intraoperative aid in parotid gland surgery. To date, however, there are few scientific studies on the postoperative outcomes of submandibular gland surgery, particularly on the postoperative injury of the marginalis mandibulae branch (MMB) of the facial nerve (FN). This branch represents the most frequent and feared complication of this surgery, with an incidence of 1-7% of cases.

OBJECTIVE

This retrospective study aims to evaluate the incidence of postoperative MMB paralysis in patients undergoing submandibular sialoadenectomy for benign conditions from 2014 to 2023, focusing on the role of IFNM.

MATERIALS AND METHODS

The patients were divided into two groups: the subjects of Group 1 (G1) had undergone submandibular sialoadenectomy after identification and clamped facial vessels, without the aid of IFNM (from 1 January 2014 to 31 December 2018). Conversely, subjects in Group 2 (G2) underwent IFNM procedures (from 1 January 2019 to 31 December 2023). The classification of any FN malfunctions was conducted following the House-Brackmann grading system. A descriptive analysis was performed, and univariate and multivariate logistic regressions were used to examine the impact of IFNM on surgical timing and the association between G2 deficit (vs. G1) corrected for age, sex, and smoking status.

RESULTS

The study population comprised a total of 101 patients with a mean age of 55 ± 16 years. The sample population comprised 50 subjects assigned to Group 1 (49.5%, 24 females and 26 males) and 51 subjects assigned to Group 2 (50.5%, 21 males and 30 females). Postoperative paralysis of the MMB occurred in 23 subjects (22.77%), including 12 of G1 (4 had a grade II and 8 grade III dysfunction) and 11 of G2 (8 had a grade II and 3 grade III dysfunction). A six-month evaluation revealed that only five patients in G1, previously diagnosed with grade II dysfunction, exhibited a residual deficit. The mean surgical time for the entire patient cohort was 99 ± 44 min: 110 ± 43 min for Group 1 and 92 ± 42 min for Group 2 (Beta = -19; 95% CI -37 at -0.16; p-value = 0.048). Furthermore, a longer operative time was observed in smokers than in non-smokers (p-value = 0.008), suggesting that smoking affects the length of surgery (Beta = 0.32; 95% CI -0.08 to -0.55).

DISCUSSION AND CONCLUSIONS

MMB paralysis is one of the most prevalent complications that may arise in submandibular gland surgery. IFNM provides surgeons with a valuable tool for identifying MMB in submandibular sialoadenectomy. The efficacy of IFNM as an aid is contingent upon the expertise of the operating surgeon.

True Incidence of Marginal Mandibular Nerve Palsy following Neonatal Mandibular Distraction Osteogenesis

BACKGROUND

In children with Pierre Robin sequence (PRS), mandibular distraction osteogenesis (MDO) is routinely performed to alleviate airway obstruction; however, it involves risk of injury to the marginal mandibular nerve (MMN). The authors hypothesize that MMN palsy incidence following MDO, reported at 1% to 15%, is underestimated. This study investigates the true incidence of MMN palsy after MDO to better guide follow-up care and improve treatment of this complication.

METHODS

A retrospective review of PRS patients who underwent MDO at a single, tertiary pediatric hospital between September of 2007 and March of 2021 was conducted. Patients who underwent MDO younger than 1 year of age and had postoperative clinical evaluations detailing MMN function were included. Logistic regression analysis was performed to investigate predictors of MMN injury.

RESULTS

Of 93 patients who underwent MDO, 59.1% met inclusion criteria, 56.4% were female, 43.6% were syndromic, and average age at MDO was 1.52 ± 2.04 months. The average length of mandibular distraction was 17.3 ± 4.36 mm, the average duration of intubation was 6.57 ± 2.37 days, and the average time until hardware removal was 111.1 ± 23.6 days. Sixteen patients (29.1%) presented with permanent MMN dysfunction, consisting of 8 patients with bilateral weakness and 8 with unilateral weakness. An additional 5 patients (9.1%) presented with transient MMN weakness that resolved within 1 year. Average length of follow-up postoperatively was 6.02 years, and no significant predictors of nerve injury were found.

CONCLUSION

In this 14-year review of patients with PRS who underwent MDO, 38.2% demonstrated evidence of MMN palsy (permanent, 29.1%; transient, 9.1%), which is much greater than previously described.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Variability of the Cervical Branch Depending on the Facial Nerve Branching Pattern and Anthropometric Type of the Head

(1) Background: Considering that the specialty literature supplies only general data about the variability of the cervical branch of the facial nerve, this study aimed to determine this branch's variation and individual peculiarities depending on the nerve branching pattern and anthropometric type of the head. (2) Methods: The study was conducted on 75 hemifaces of adult formalized cadavers. Ahead of anatomical dissection, each head was measured to establish the anthropometric type, according to Franco and colleagues. The branching patterns were then distributed according to the Davis classification. (3) Results: The number of cervical branches (CB) of the facial nerve varied from one to five branches, with the following rate: 1 CB (61.3%), 2 CB (28%), 3 CB (6.7%), 4 CB (2.7%), and 5 CB (1.3%). Seven branching patterns of the facial nerve were revealed: Type I in 18.7%, Type II in 14.7%, Type III in 20%, Type IV in 14.6%, Type V in 5.3%, Type VI in 18.7%, and Type NI in 8% (bizarre types). According to the branching pattern, the mean numbers of the cervical branches were as follows: Type I-1.6 ± 1.02; Type II-1.4 ± 0.50; Type III-1.4 ± 0.50; Type IV-1.4 ± 0.67; Type V-2.0 ± 1.41; Type VI-1.8 ± 1.12; and Type-NI-1.8 ± 0.75; p = 0.599. According to the anthropometric type of the head, the mean number of CB in the mesocephalic type (MCT) was 1.5 ± 0.82, in the dolichocephalic type (DCT), 1.7 ± 0.87, and in the brachycephalic type, (BCT) 1.8 ± 1.04; p = 0.668. (4) Conclusions: The cervical branch of the facial nerve varies depending on the facial nerve branching pattern and the anthropometric type of the head. The highest degree of variation was characteristic of BCT and Type V and the lowest, of MCT and Types II, III, and IV.

Use of neuromuscular blockade for neck dissection and association with iatrogenic nerve injury

BACKGROUND

Cranial nerve injury is an uncommon but significant complication of neck dissection. We examined the association between the use of intraoperative neuromuscular blockade and iatrogenic cranial nerve injury during neck dissection.

METHODS

This was a single-center, retrospective, electronic health record review. Study inclusion criteria stipulated patients > 18 years who had ≥ 2 neck lymphatic levels dissected for malignancy under general anesthesia with a surgery date between 2008 - 2018. Use of neuromuscular blockade during neck dissection was the primary independent variable. This was defined as any use of rocuronium, cisatracurium, or vecuronium upon anesthesia induction without reversal with sugammadex prior to surgical incision. Univariate tests were used to compare variables between those patients with, and those without, iatrogenic cranial nerve injury. Multivariable logistic regression determined predictors of cranial nerve injury and was performed incorporating Firth's estimation given low prevalence of the primary outcome.

RESULTS

Our cohort consisted of 925 distinct neck dissections performed in 897 patients. Neuromuscular blockade was used during 285 (30.8%) neck dissections. Fourteen instances (1.5% of surgical cases) of nerve injury were identified. On univariate logistic regression, use of neuromuscular blockade was not associated with iatrogenic cranial nerve injury (OR: 1.73, 95% CI: 0.62 - 4.86, p = 0.30). There remained no significant association on multivariable logistic regression controlling for patient age, sex, weight, ASA class, paralytic dose, history of diabetes, stroke, coronary artery disease, carotid atherosclerosis, myocardial infarction, and cardiac arrythmia (OR: 1.87, 95% CI: 0.63 - 5.51, p = 0.26).

CONCLUSIONS

In this study, use of neuromuscular blockade intraoperatively during neck dissection was not associated with increased rates of iatrogenic cranial nerve injury. While this investigation provides early support for safe use of neuromuscular blockade during neck dissection, future investigation with greater power remains necessary.