The phrenic nerve; the forgotten nerve in head and neck surgery.

BACKGROUND: Neck dissection is a commonly performed procedure for oncologic control of head and neck malignancy. With contemporary modified radical and selective neck dissections, haematoma, wound infection, tissue necrosis, chyle leak and injury involving the marginal mandibular, hypoglossal, vagus or accessory nerves are commonly described complications. Although the phrenic nerve courses within the surgical planes explored during a neck dissection and has a vital function in innervating the diaphragm, few studies have been performed to investigate the exact incidence of post-operative phrenic nerve paresis. This study aims to review the literature as to the rate of phrenic nerve injury following neck dissection. METHODS: A systematic literature review was conducted from 2000 to 2022 including studies reporting on phrenic nerve paresis following neck dissection. RESULTS: In total, 11 studies were included. The reported rate of immediate post-operative phrenic nerve paresis ranged from 0% to 5.3%, with an average rate of 0.613% (12/1959). The reported rate of phrenic nerve paresis at follow-up (1 month-127 months) ranged from 0% to 4.7%, with an average rate of 1.035% (5/483). There were no cases of bilateral phrenic nerve paresis reported in this period. CONCLUSIONS: Phrenic nerve paresis is an uncommon complication following neck dissection, often asymptomatic and potentially underreported. Bilateral phrenic nerve paresis is exceedingly rare. Injury can be avoided by staying superficial to the prevertebral fascia when dissecting around the anterior scalene muscle. Routine phrenic nerve integrity monitoring is not commonly utilized but may aid intra-operative phrenic nerve identification or confirmation of function.

Translaryngeal ultrasound in thyroid surgery: state of the art review.

BACKGROUND: Clinical voice assessment prior to thyroid and parathyroid surgery is essential, but the paradigm of indirect laryngoscopy (IDL), when indicated, has been challenged by the risk of aerosolised SARS-Cov-2 during endoscopy of the aerodigestive tract. Translaryngeal ultrasound (TLUS) to assess the vocal cords has been proposed as a safe, non-invasive and sensitive alternative. The aim of this review was to verify TLUS as a viable tool for perioperative laryngeal assessment. METHOD: A literature review was performed using Medline, Embase, Cochrane Database of Systematic Reviews, Cochrane Database of Abstracts of Reviews of Effects, Cochrane Central Register of Controlled Trials and Scopus with the following search strategy: (vocal cord OR vocal fold OR glottic OR glottis OR vocal ligaments OR rima glottidis) AND (ultras* OR sonograph* OR echography OR echotomography). RESULTS: Fifteen studies were included in this review. All studies compared TLUS to IDL in visualizing the vocal cords in adults. Ten studies compared pre-operative TLUS to IDL where 50.6-100% of vocal cords were successfully visualized. Nine studies compared post-operative TLUS to IDL and reported visualization between 39.6% and 100%. Pre- and post-operative negative predictive values ranged from 60% to 100%. CONCLUSION: Whilst promising, successful visualization of the cords is limited by inter-user variability, older age and male gender. Thus, we see the role of TLUS as an alternative to IDL in the post-operative setting in the young patient following uncomplicated surgery with a normal voice on clinical examination, to confirm recurrent laryngeal nerve integrity while minimizing the risk of aerosolization.

Tumor thickness versus depth of invasion - Analysis of the 8th edition American Joint Committee on Cancer Staging for oral cancer.

OBJECTIVES: The primary aim of this study is to compare the effect of using tumor thickness versus depth of invasion (DOI) to determine the 8th edition AJCC T-category on survival in a large cohort of OSCC. MATERIALS AND METHODS: A retrospective cohort study of patients whose clinicopathologic information had been collected prospectively into a dedicated head and neck database. 927 patients with oral SCC were identified in this cohort, with the final study population including 456 patients with complete information on DOI, tumor thickness, T and N staging and follow-up. RESULTS: 26 (5.7%) patients had a different AJCC 8 T category when using thickness instead of depth. 15 were upstaged from T1 to T2, 10 upstaged from T2 to T3 and 1 down staged from T2 to T1. Additionally, similar stratification of disease-specific and overall survival curves were found for T category based on DOI and thickness. CONCLUSION: The T category and TNM stage prognostic performance of 8th edition AJCC staging of oral cancer is similar regardless of whether DOI or thickness is used as the T-category modifier. In centers without complete DOI data it is reasonable to impute thickness for retrospective survival analyses using the 8th edition of the AJCC staging system.