Functional MR imaging of submandibular herniation of sublingual tissues through a gap of the mylohyoid muscle in two cases of submandibular “masses”

Submandibular swelling, pulsations and otalgia due to sublingual gland and blood vessels herniation through mylohyoid boutonnière: Case report

Background/Aim: Mylohyoid boutonnière is a common anatomical variant with extremely rare clinical manifestations. We report two cases of symptomatic unilateral mylohyoid boutonnière with sublingual gland herniation. Case report: The first was a 34-year-old female with a two months history of a left submandibular swelling, intermittent pulsations, and otalgia. The second 67-year-old female presented with a left submandibular pain six months after total thyroidectomy due to papillary carcinoma. After detailed clinical and radiological evaluation by ultrasonography (US) and computed tomography (CT), the mylohyoid gap with sublingual gland herniation was diagnosed in both patients. The dynamic US with a tongue pressed down on the mouth floor revealed blood vessel compression by a herniated sublingual gland in the first patient. Conclusions: This is the first case of a mylohyoid boutonnière related intermittent vascular compression. Dynamic US and CT may help to differentiate intermittent and persistent sublingual gland herniation through the mylohyoid boutonnière from other pathological lesions in the submandibular region.

Types of sublingual gland herniation observed during sonography of plunging ranulas

OBJECTIVES

Plunging ranulas have been shown to have a common trio of mylohyoid defects, sublingual gland herniation, and submandibular space fluid collections. The herniated sublingual gland may be susceptible to subclinical trauma. The purpose of this study was to investigate the frequency of occurrence of various types of active sublingual gland herniation observed during diagnostic sonographic studies.

METHODS

Sonographic findings of sublingual gland herniation from 76 patients with a total of 80 plunging ranulas are presented. All sublingual gland herniations, including those on the contralateral side, were documented at the time of the examinations and reviewed later. The sonographic appearances of active sublingual gland herniation were given the names "slide," "wobble," "mushroom," and "retrusion" to reflect the observed movement.

RESULTS

Mylohyoid defects were found in 98% of plunging ranulas. The different types of sublingual gland herniation observed were as follows: slide in 77.8%, wobble in 11.1%, mushroom in 9.7%, and retrusion in 1.4%. The unaffected contralateral side showed a wobble in 44.8% of cases and slide in 8.9%.

CONCLUSIONS

Sublingual gland herniation through mylohyoid defects is easily missed if one is unaware. Prior knowledge of the various types of sublingual gland herniation and their frequencies of occurrence are very helpful during diagnostic sonographic examinations.

Dynamic sonography and CT findings of unilateral submandibular gland agenesis associated with herniated hypertrophic sublingual gland

Congenital agenesis of the submandibular gland is uncommon. We report dynamic sonography and CT findings of the unilateral submandibular gland agenesis associated with herniated hypertrophic sublingual gland tissue through the mylohyoid gap. The dynamic sonography examination applied at rest and during the modified Valsalva maneuver demonstrated hypertrophied sublingual gland prolapsing to the anterior part through the mylohyoid gap. This may be the first reported case describing dynamic sonography findings of this entity. CT confirmed the agenesis of the left submandibular gland and compensatory hypertrophy of the ipsilateral sublingual gland.

Postmortem investigation of mylohyoid hiatus and hernia: aetiological factors of plunging ranula

The mylohyoid hiatus and hernia were discovered in the nineteenth century and were considered to explain the origin of the plunging ranula from the sublingual gland. This formed the rationale for sublingual sialadenectomy for the treatment of plunging ranula. However, a more recent, extensive histological investigation reported that hernias contained submandibular gland, which supported an origin of the plunging ranula from the submandibular gland and submandibular sialadenectomy for the treatment of plunging ranula. We therefore decided to investigate the occurrence and location of the hiatus and the histological nature of the hernia. Twenty-three adult cadavers were dissected in the submandibular region. The locations and dimensions of mylohyoid hiatuses were measured before taking biopsies of hernias. Hiatuses with associated hernias were found in ten cadavers: unilateral in six; and bilateral in four, in one of which there were three hiatuses. Sublingual gland was identified in nine hernias and fat without gland in six. This investigation supports clinical and experimental evidence that the plunging ranula originates from the sublingual gland and may enter the neck through the mylohyoid muscle. It confirms the rationale of sublingual sialadenectomy for the treatment of plunging ranula.

Imaging of the mylohyoid muscle: separation of submandibular and sublingual spaces

OBJECTIVE

This article focuses on the anatomy of the mylohyoid muscle, a crucial landmark in imaging of the oral cavity and upper neck, showing dissected specimens and CT and MR images.

CONCLUSION

Identification of the relationship of a lesion in the sublingual space to the mylohyoid muscle using MDCT and high-resolution MRI is a key part of the imaging assessment of the oral cavity and upper neck.

Incidence and clinical relevance of herniation of the mylohyoid muscle with penetration of the sublingual gland

Swelling of the submandibular region may cause problems in daily clinical diagnosis and requires further exploration. Ultrasonic examination provides a simple, non-invasive and radiation-free method. The goal of our study was to show the high incidence of herniation of the mylohyoid muscle with penetration of the sublingual glands, in some cases clinically imposing as permanent swelling. Penetration was classified into four grades (Grade 0-III). In course of routine examinations of the neck by ultrasound, the anterior part of the mylohyoid muscle was observed in 124 consecutive patients from our outpatient's clinic, presenting with unclear swelling of the neck, mostly due to lymph nodes. In resting position and during swallowing the degree of penetration of the sublingual gland through the mylohyoid muscle was staged. Almost 60% of patients showed an affection of the mylohyoid muscle at either site of varying degrees. In 40% only a thinning of the muscle could be noticed (grade I), whereas in 21 patients (17%) a significant herniation of the gland during swallowing could be observed (grade II). In two patients (2%) a constant breach of the mylohyoid muscle with permanent herniation of the gland imposing as swelling could be seen (grade III). Occasional or permanent penetration of the sublingual gland through the mylohyoid muscle is not a rare finding and can be found in almost every fifth individual using ultrasound. This may impose clinically as permanent swelling and may be of value in the differential diagnosis of swelling in the submandibular region.