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

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.

Ten must know pseudolesions of the head and neck

Patients may present in the emergency setting for a variety of head and neck complaints such as fever, trouble swallowing, or a newly palpable mass. When reviewing radiologic head and neck exams for etiology of complaints, it is important to be familiar with the multiple pseudolesions that may mimic pathology. These may be normal variant anatomy, normal anatomy located in an atypical location, as well as iatrogenic or self-introduced foreign bodies. This review article discusses ten common pseudolesions encountered in the head and neck and their typical imaging appearance so that one does not mistake them for ominous pathology, thus preventing unnecessary follow-up, biopsy, or continued concern for the patient.

Sonographic diagnosis in the head and neck region: from an educational lecture presented at the 56th General Assembly and Annual Scientific Congress of the Japanese Society for Oral and Maxillofacial Radiology

Sonography is a simple, inexpensive, and non-invasive diagnostic modality. Although tissues behind bony structures and deep tissues are not delineated, sonography can depict superficial soft tissues very clearly. In the head and neck region, however, it has not yet been used widely, as the anatomical structures are complicated, and considerable experience is needed both to perform an examination and to make a diagnosis. To perform examinations efficiently, operators must be familiar with the sonographic system in use, and take images at standard planes. To make a correct diagnosis, operators require knowledge of the sonographic anatomy on standard planes, representative sonographic signs and artifacts, and common diseases and their typical sonographic findings. In this paper, we have explained the sonographic anatomy on standard planes, and the sonographic findings of common diseases in the oral and maxillofacial region.

A cadaveric study on mylohyoid herniation of the sublingual gland

The purpose of this study was to document the presence of a sublingual gland (SLG) herniating inferiorly through the mylohyoid muscle into the submandibular area. A total of 100 half-heads of 50 adult Korean cadavers were enrolled in this study. The floor of the mouth was dissected from the neck, and mylohyoid muscle patency and position of the sublingual gland were evaluated. Demographic factors of the donor and characteristics of the herniation were evaluated. Herniation was found in 29 (58.0 %) of the 50 cadavers or 42 of the 100 half-heads. Herniation was more frequently observed in females than in males (p = 0.009). However, no laterality was observed. Classifying the location of SLG herniation from the midpoint of the mandible to the hyoid bone into 3 regions, 32 (63 %) of herniations were found in the anterior one-third. No ranula formation was observed. The size and weight of normal glands tended to be larger than those of herniated glands, but no statistical significance was observed. An SLG hernia is a very common condition and is more frequently observed in females. As such, SLG herniation should be considered when a submental neck mass is evaluated.

Plunging Ranulas Revisited: A CT Study with Emphasis on a Defect of the Mylohyoid Muscle as the Primary Route of Lesion Propagation

Objective

The purpose of this study was to clarify the pathogenesis of plunging ranulas in regard of the pathway of lesion propagation using CT scans.

Materials and Methods

We retrospectively reviewed CT scans of 41 patients with plunging ranula. We divided plunging ranulas into two types: type 1 was defined as those directly passing through a defect of the mylohyoid muscle with the presence (type 1A) or absence (type 1B) of the tail sign and type 2 as those through the traditional posterior route along the free edge of the mylohyoid muscle. Images were also analyzed for the extent of the lesion in respect to the spaces involved. As for type 1 lesions, we recorded the location of the defect of the mylohyoid muscle and the position of the sublingual gland in relation to the defect.

Results

CT scans demonstrated type 1 lesion in 36 (88%), including type 1A in 14 and type 1B in 22, and type 2 lesion in 5 (12%). Irrespective of the type, the submandibular space was seen to be involved in all cases either alone or in combination with one or more adjacent spaces. Of the 36 patients with type 1 lesions, the anterior one-third was the most common location of the defect of the mylohyoid muscle, seen in 22 patients. The sublingual gland partially herniated in 30 patients.

Conclusion

Our results suggest that the majority of plunging ranulas take an anterior shortcut through a defect of the mylohyoid muscle.

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.

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 the oral cavity: key concepts for the radiologist

The oral cavity is a challenging area for radiological diagnosis. Soft-tissue, glandular structures and osseous relations are in close proximity and a sound understanding of radiological anatomy and common pathways of disease spread is required. In this pictorial review we present the anatomical and pathological concepts of the oral cavity with emphasis on the complementary nature of diagnostic imaging modalities.

Modern management and pathophysiology of ranula: literature review

BACKGROUND

There is a lack of consensus about the appropriate treatment of ranula. The objective of the present investigation was to produce a scientific basis for treatment.

METHODS

A review of the relevant literature is interpreted in the light of improved knowledge about the local anatomy and the pathophysiology of the salivary glands.

RESULTS

The oral and plunging ranulas are cystic extravasation mucoceles that arise from the sublingual gland and usually from a torn duct of Rivinus. The sublingual gland is a spontaneous secretor and the salivary flow is resistant to obstruction, which is caused by fibrosis induced by the extravasation. The submandibular gland is not a spontaneous secretor, is less resistant, and does not give rise to ranulas.

CONCLUSIONS

Effective treatment is removal of the involved unit of the sublingual gland or inducing sufficient fibrosis to seal the leak through which the mucus extravasates.

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.