Abstract
Objective
To investigate usefulness of the methylene blue staining for parotid gland surgery.
Study design
Randomized, prospective controlled trial.
Methods
The study analyzed 144 surgical operations (2000–2014) for parotidectomy. The cases were randomly divided into two groups: Group 1 (n = 70) for surgeries with methylene blue staining, and Group 2 (n = 74) for surgeries without staining. Surgical complications like temporary facial weakness, permanent facial nerve injury, and Frey’s syndrome were taken for comparison between groups as well as rate of tumor recurrence.
Results
Temporary facial weakness and Frey’s syndrome occurred almost evenly in both groups (p = 0.34, p = 0.68 respectively). Permanent facial nerve injury was significantly lower in the group with staining (p = 0.032) and the decline of rate of tumor recurrence was even more significant (p = 0.007).
Conclusion
Intravital staining with methylene blue in parotidectomies simplifies the operation and could assist in better visualization that leads to (1) rapid and precise localization of the tumor, (2) preservation of the facial nerve, and (3) complete removal of the gland tissue in cases with malignancy. This technique reduces the rate of recurrence in cases with malignant tumors.
Level of evidence: 1.
1
Introduction
The specific surgical morbidity remains significant in parotid gland surgery. In addition to temporary facial weakness and permanent facial nerve injury, postparotidectomy depression and Frey’s syndrome (gustatory sweating) are specific for this type of surgery. To reduce the surgical morbidity, several modifications of parotidectomy have been implemented but postsurgical complications remain especially facial nerve injury .
To overcome this difficulty, an identification method might be used such as preoperative intravital staining of the gland with methylene blue (methylthionine chloride) (MB). Although MB staining is not designed to be used as a sole technique, it can be combined with other techniques such as identification of the anatomic landmarks. MB staining is simple, inexpensive, and not time consuming technique.
MB dye was used in histology since XIX century. The modern usage of MB vital staining began in early 1950s when surgeons used vital staining in biliary and duodenal surgery . The safety of the MB staining was previously confirmed .
Already in the 1960s, MB staining was successfully introduced into the surgery of the parotid gland . The results of its use appeared to be very successful in cases with tumors, foreign bodies, and sialolithiasis. Since 1970s, MB staining of the parotid gland became an accepted surgical procedure but it did not become a widely used technique. There are only 16 articles on the method in the PubMed starting from the abovementioned article of 1962. Of them, only six articles were dedicated to MB staining of the gland tissue in cases of tumor excision. The last of them was published in 2006 .
Our main objective was to investigate usefulness of the method in various techniques of parotidectomy in cases of benign and malignant tumors and safety of the MB staining for this type of surgery.
2
Materials and methods
The study analyzed 144 surgical operations (2000–2014) for parotidectomy in cases with salivary gland tumors. In all cases the diagnosis was confirmed by CT and/or MRI investigation. CT/MRI evaluation of patients was performed also for preoperative evaluation of tumor location. The study protocol conformed to the ethical guidelines of the 1975 Declaration of Helsinki (amended 2000) as reflected a priori after approval by the institution’s Helsinki committee.
The patients were randomly chosen among surgical patients in the hospital across a 15-years period according to a predetermined randomization code. The sealed envelope method was used. The inclusion criterion: All selected adult patients had primary benign or malignant parotid tumors. Cases with secondary tumors of the gland were excluded from the studies. The patients flow was as follows: assessed for eligibility n = 172, not meeting inclusion criteria n = 23, randomized n = 149, did not receive allocated intervention because of counter indications for surgery n = 5, and analyzed n = 144.
The cases were randomly divided into two groups: Group 1 (MB Group, n = 70; F 26, M 44; mean age 38 years) for surgeries with MB staining, and Group 2 (control group, n = 74; F 35, M 39; mean age 43) for surgeries without staining that served as a control group. Surgical complications such as temporary facial weakness, permanent facial nerve injury, post-operative hematoma, salivary fistula, and Frey’s syndrome were taken for comparison between groups as well as incidence of tumor recurrence. Three different surgeons experienced in salivary gland surgery operated on these patients.
The confirmation of diagnosis was achieved by CT, MRI, or CT/MRI investigations (n = 106, 73.6% of cases), ultrasonography (100%), and FNAB (100%).
The type of the surgery was chosen according to CT, or MRI data and FNAB. All surgeries were performed under general anesthesia. The types of operations performed included partial and standard superficial parotidectomies, selective deep lobe parotidectomies, and total parotidectomies. All types of the operation were performed with the assistance of the nerve detector. Our patients did not receive intraoperative steroids therapy. Cases with both benign and malignant tumors were included. The data on types of operations and tumor classification are presented in Table 1 .
