The effect of surgical resection in the region of the retromolar trigone

An Exploratory Investigation of the Palatoglossus Muscle in Children Using Magnetic Resonance Imaging

PURPOSE

There is currently little evidence reporting the typical morphology of the palatoglossus (PG) muscle. The primary purpose of this exploratory study is to determine whether magnetic resonance imaging (MRI) methods used to quantify the morphology of the levator veli palatini (LVP) muscle can be applied to the PG. The secondary purpose is to provide preliminary data regarding the relationship between the LVP and PG muscles in children.

METHOD

Ten children between ages of 4 and 7 years participated in this study. Each participant was scanned using a nonsedated, child-friendly protocol with a T2-weighted, three-dimensional anatomical scan to obtain images of the oropharyngeal anatomy. Custom, oblique-coronal image planes were created to visualize and measure the LVP and PG muscles in their entirety from origin to insertion. Thermo Scientific Amira Software was used to obtain 2D measurements of PG muscle length, width, velar insertion distance, lingual insertion distance, and several angle measurements.

RESULTS

The PG ranged from 17.95 to 26.96 mm in length across participants. Velar insertion distance ranged from 17.22 to 30.95 mm. Lingual insertion distance ranged from 26.91 to 36.02 mm. Width ranged from 2.32 to 3.08 mm. The angle formed by the PG and LVP muscle planes ranged from 7.3° to 52.7°. The LVP insertion angle ranged from 42.5° to 75.9°. The PG insertion angle ranged from 16.9° to 52.3°.

CONCLUSIONS

MRI was successful in visualizing the PG muscle. The PG was consistent in size and shape within an individual participant but varied across the participant cohort.

Treatment Outcomes of Rare Retromolar Trigone Squamous Cell Carcinoma Using Combined Modalities

Background

Retromolar trigone squamous cell carcinoma is relatively uncommon and due to its complex anatomy has always remained a challenge in terms of loco-regional control and survival. Surgery, radiotherapy, and chemotherapy as combined modalities have been used but high recurrence rates result in poor outcome.

Methods

We have retrospectively evaluated records of 62 patients treated in Head and Neck Oncology unit of Shaukat Khanum Memorial Cancer Hospital and Research Centre (SKMCH and RC), Lahore, Pakistan from 2004 to 2014 who were included based on the criteria of histopathological proven squamous cell carcinoma of retromolar trigone (RMT) treated with radical intent. Diagnostic workup for all patients involved clinical examination, imaging modalities usually magnetic resonance imaging (MRI), computerized tomography (CT), Orthopantomogram (OPG), and chest x-ray (CXR) to evaluate regional and distant metastasis, respectively. Kaplan-Meier survival curves were used to depict survival.

Results

The study was comprised of 36 male and 26 female patients. Treatment modalities used are surgery only (n = 1), radiotherapy alone (n = 13), radiotherapy followed by surgery (n = 10), chemoradiotherapy (n = 16), induction chemotherapy followed by concurrent chemoradiotherapy (n = 19), induction chemotherapy followed by surgery, and radiotherapy (n = 2). Surgical interventions include wide local excisions (n = 6), marginal mandibulectomy (n = 4), and segmental mandibulectomy (n = 4). Surgical margins were clear in 54%, close in 38%, and involved in 8% of patients. AJCC 7th edition showed cT1 8%, cT2 22%, cT3 14%, and cT4 56% while pT1 2%, pT2 3%, and pT4 8%. During follow-up, 18% patients have come up with local recurrence, 22% showed persistent disease while 9% have presented with distant metastasis. The five-year and overall survivals are 38% and 22%, respectively.

Conclusion

Retromolar trigone involvement poses many vital structures at risk of involvement. Late presentation results in involvement of masticator space compromising both mouth opening and surgical outcomes. Surgery and radiotherapy have shown comparable results in disease control. Bone invasion has shown poor outcome in terms of loco-regional control and overall survival.

Variation in Lingual Nerve Course: A Human Cadaveric Study

The lingual nerve is a terminal branch of the mandibular nerve. It is varied in its course and in its relationship to the mandibular alveolar crest, submandibular duct and also the related muscles in the floor of the mouth. This study aims to understand the course of the lingual nerve from the molar area until its insertion into the tongue muscle. This cadaveric research involved the study of 14 hemi-mandibles and consisted of two parts: (i) obtaining morphometrical measurements of the lingual nerve to three landmarks on the alveolar ridge, and (b) understanding non-metrical or morphological appearance of its terminal branches inserting in the ventral surface of the tongue. The mean distance between the fourteen lingual nerves and the alveolar ridge was 12.36 mm, and they were located 12.03 mm from the lower border of the mandible. These distances were varied when near the first molar (M1), second molar (M2) and third molar (M3). The lingual nerve coursed on the floor of the mouth for approximately 25.43 mm before it deviated toward the tongue anywhere between the mesial of M1 and distal of M2. Thirteen lingual nerves were found to loop around the submandibular duct for an average distance of 6.92 mm (95% CI: 5.24 to 8.60 mm). Their looping occurred anywhere between the M2 and M3. In 76.9% of the cases the loop started around the M3 region and the majority (69.2%) of these looping ended at between the first and second molars and at the lingual developmental groove of the second molar. It gave out as many as 4 branches at its terminal end at the ventral surface of the tongue, with the presence of 2 branches being the most common pattern. An awareness of the variations of the lingual nerve is important to prevent any untoward complications or nerve injury and it is hoped that these findings will be useful for planning of surgical procedures related to the alveolar crest, submandibular gland/ duct and surrounding areas.

Retromolar trigone squamous cell carcinoma treated with radiotherapy alone or combined with surgery: a 10-year update

PURPOSE/OBJECTIVES

Treatment outcomes were analyzed for patients who received radiotherapy for squamous cell carcinoma of the retromolar trigone at a single institution.

MATERIALS/METHODS

We reviewed the medical records of 110 patients treated with radiotherapy alone (n=36) or radiotherapy combined with surgical resection of the primary tumor (n=74) between June 1966 and October 2013. The median follow-up was 4.5years for all patients and 11.8years for living patients (range, 1.3-23.5years).

RESULTS

The 5-year local-regional control rates after definitive radiotherapy versus surgery and radiotherapy for stages I-III were 52% and 89% and for stage IV they were 46% and 58%, respectively. The 5-year cause-specific survival rates after definitive radiotherapy compared with surgery and radiotherapy for stages I-III were 57% and 82% and for stage IV they were 45% and 43%, respectively. Multivariate analyses revealed that the likelihood of cure was better with surgery and radiotherapy compared with radiotherapy alone (p=0.041).

CONCLUSION

Patients treated with surgery and radiotherapy had a better chance of cure than those treated with radiotherapy alone. Complications of treatment were common in both groups but more common in patients who underwent surgery.