New anatomical findings in the mandibular body region: Two parts that make up bucco-mandibular space.

Soft tissue spaces not only enable gliding by contraction of the facial muscles, but they also cause drooping of the superficial fat due to gravity in the upright position. This study was performed to clarify the structures around the bucco-mandibular space (BMS) and to apply this anatomical knowledge to clinical practice. Four sides of the face were dissected using a conventional gross anatomical dissection technique, and 10 sides (5 horizontal and 5 frontal sections) of the removed semi-facial soft tissue were dissected using the stretched tissue dissection (STD) method. Histological examination of the mandible was performed on two sides to confirm the findings of conventional gross anatomical dissection and STD. In all cases, both gross dissection and STD revealed that the BMS was composed of two parts. The superficial part was filled with adipose tissue containing nerves and vessels, including the marginal mandibular branch of the facial nerve, facial artery, facial vein, and mental nerve. We named this part the adipo-neuromandibular part. By contrast, the deep part was separated from the adipo-neurovascular part by facial deep fascia and composed of loose connective tissue. We named this deep part the loose connective tissue part. The STD method enabled us to obtain detailed anatomical findings of the mandibular region and elucidate two parts of the BMS in which the neurovasculature is distributed. We believe that these findings provide new insights into facial anatomy by resolving existing anatomical uncertainties and will contribute to safer surgical treatment in the facial region.

A new injection method for identifying the subpopliteal recess of the knee.

The posterolateral region of the knee has a complex and diverse anatomy. Hydrarthrosis of the knee can potentially communicate with other parts of the joint space. The joint fluid distribution reflects anatomical communications between synovial spaces. To observe the continuity between the knee joint cavity and the surrounding bursa, we devised a dissection method with a new injection agent, an eosin-containing congealed liquid that spreads uniformly over the entire space. The purpose of this study was to perform a detailed examination of the subpopliteal recess (SPR) where a bursa connects to the knee joint capsule. We also reported the advantages of this new injection agent compared with conventional materials (latex and epoxy resin). Twenty-two formalin-fixed cadavers (34 knees), two N-vinyl-pyrrolidone (NVP)-fixed cadavers (4 knees), and two cadavers (3 knees) fixed by Thiel's method were used. After filling the knee joint space and SPR with eosin congealed liquid, the specimens were dissected to investigate the morphology of the SPR. In addition, three different types of injection agents were assessed. The SPR extended distally along the popliteus tendon. The SPR length was 22.64 ± 11.38 mm from the upper end of the lateral tibial condyle to the lower end of the depression. The existence of a fabellofibular ligament made the SPR significantly longer, but abrasion of the femoral articular cartilage did not affect the SPR. Furthermore, the relationship between the popliteus muscle and the SPR was classified into three types (types 1-3). Types 2 and 3 in which the SPR extended to the proximal tibiofibular joint may cause instability of the knee joint. The eosin congealed liquid was highly useful in many aspects, such as fluidity and injection workability. The new dissection method with eosin congealed liquid provides insights into the anatomy of the posterior lateral knee, which are useful for radiological diagnoses and clinical treatments.

Double Inferior Vena Cava with Major Predominance of the Left Inferior Vena Cava: A Cadaver Case Report.

We encountered a case of a double inferior vena cava with major predominance of the left inferior vena cava during an anatomical dissection course for medical students in 2015. The right inferior vena cava (normal inferior vena cava) was 2.0 mm wide, and the left inferior vena cava was 23.2 mm wide. The fine right inferior vena cava began at the right common iliac vein, ascended along the right side of the abdominal aorta, and then joined the left inferior vena cava at the level of the lower margin of the first lumbar vertebra. The dominant left inferior vena cava started from the left common iliac vein and ascended along the left side of the abdominal aorta. Most patients with a double inferior vena cava are asymptomatic, and these variants are incidentally detected by computed tomography or magnetic resonance imaging. Their presence may have significant implications for surgery, particularly abdominal surgery in patients with paraaortic lymphadenopathy and in those undergoing laparoscopic radical nephrectomy or inferior vena cava filter placement. We herein discuss the embryology of a double inferior vena cava based on detailed anatomical data of the variations of a double inferior vena cava, including those that require clinical attention.

The Key Structure of the Facial Soft Tissue: The Superficial Musculoaponeurotic System.

The superficial musculoaponeurotic system (SMAS) was advocated by Mitz and Peyronie in 1976. The concept of this superficial fascia was established by surgical findings of facelift surgery and is familiar to plastic surgeons and anatomists. However, detailed characteristics of this fascia are still not widely known among head and neck surgeons. Moreover, the SMAS is generally located at the parotid and cheek regions and divides facial fat into superficial and deep layers. The SMAS connects to the superficial temporal fascia cranially and to the platysma caudally. The frontal muscle and the peripheral part of the orbicularis oculi are also in the same plane. The exact expanse of the SMAS in the face is controversial. Some authors claimed that the SMAS exists in the upper lip, whereas others denied the continuity of the SMAS to the superficial temporal fascia in a histological study. There are various other opinions regarding SMAS aside from those mentioned above. The concept of the SMAS is very important for facial soft tissue surgeries because the SMAS is a good surgical landmark to avoid facial nerve injuries. Therefore, this article summarized SMAS from an anatomical point of view.

An Anatomical Dissection Method for Observation of Fibrous Facial Structures.

BACKGROUND: In recent years, structures including the superficial musculoaponeurotic system and retaining ligaments that support the facial soft tissue have been clarified. However, these structures are very difficult to observe in their entirety by the standard gross anatomical procedure (ie, dissection from superficial to deep layers). Furthermore, accurate descriptions of these structures are rare in both anatomical and plastic surgery textbooks. The aim of this study was to clarify the facial fibrous structures in a gross anatomical view. METHODS: The authors' novel method used soft facial tissue and bone. The tissue was fixed in gelatin and sectioned at a thickness of 5 to 10 mm. Each section was placed on a wooden board; the bone was then pinned, and the skin was pulled outward with sutures to hyperextend the soft tissue. Subsequently, the loose connective tissue was torn and fat tissue was removed under a surgical microscope. After the removal of fat tissue, the fibrous facial structures (eg, the superficial musculoaponeurotic system and retaining ligaments) could be observed clearly. RESULTS: The thickness of the sections allowed three-dimensional observation, such that a structure located deep within a section could be clearly observed. The expansion of soft tissue facilitated observation of the facial layer and fibrous structures, and the locations of nerves and vessels. Therefore, the facial layer structure was readily discerned. CONCLUSION: This method is likely to be very useful in the field of plastic surgery because it enabled intuitive identification of facial layers and their characteristics. CLINICAL RELEVANCE STATEMENT: The dissection method developed by the authors reveals the connected morphology of each tissue of the face, thus providing basic data for analyzing soft tissue changes due to aging and gravity. This will be useful for the development of anti-aging medicine.

Three sublayers in the SMAS: Observations of facial soft tissue using the stretched tissue dissection method focusing on the SMAS.

The characteristics of the superficial musculoaponeurotic system (SMAS), including the morphology of each part and the connection between tissues, remain controversial. The purpose of this study is to clarify the anatomy of the SMAS using our new dissection method. In this study, six hemi-sides of heads from formalin-preserved cadavers were used. Three were used for creating a horizontal section and three were used for creating the section along the axial line perpendicular to the surface of the skin, resulting in a gradual change from the coronal section at the lateral to the sagittal section at the median. The resected head was cut into slices with widths of 7 mm. The stretched tissue dissection method was performed by fixing a tissue slice to a board and pulling the skin outward to stretch the soft tissue. Blunt dissection was then performed under a microscope. The SMAS comprises three layers: superficial, intermediate, and deep. The superficial layer is a thin membrane directly connecting to the septa in the subcutaneous fat. The deep layer is the connective tissue in contact with the sub-SMAS structure. The layer surrounded by the superficial and deep layer of the SMAS is the intermediate layer, containing connective tissue, adipose tissue, and facial muscles. The detailed findings of the SMAS obtained using this method resolve theoretical discrepancies and provide important insight for the field of facial surgery.

Gross anatomical study of the subcutaneous structures that create the three-dimensional shape of the buttocks.

The purpose of this study was to clarify the subcutaneous structures involved in the morphology of the gluteal region for clinical application. Thirty-seven formalin-fixed cadavers and one soft-fixed cadaver were used in this study. Gluteal tissue was removed from five formalin-fixed cadavers. A horizontal section and sections parallel to the long axis of the body were made from the excised tissue, and the subcutaneous fat was removed to observe the fibrous structure within the subcutaneous fat. Two formalin-fixed cadavers and one soft-fixed cadaver were used to perform conventional gross anatomical dissection and histological examination. On 30 formalin-fixed cadavers, the thickness of the subcutaneous fat was measured in various areas of the buttocks. The thickness of subcutaneous fat was thicker in the center of the buttocks and thinner on the lateral buttocks. Superficial fascia (SF) was found only in the upper buttock, being indistinct in the lower buttock. In the sacral and coccygeal areas, the dermis was tightly adhered to the bone as a single mass. Fibers arose from around the iliac crest to the SF. On the medial side of the gluteal fold, a strong fiber arose from the sciatic tubercle and inserted into the gluteus maximus and dermis. By identifying the characteristic subcutaneous structures of the gluteal region, we were able to identify the anatomical structures that shape the three-dimensional morphology of the buttocks. These findings may be useful in surgical treatments such as improving the buttock shape.

An anaphylactic reaction after simultaneous injection of hyaluronic acid fillers and human collagen.

Anaphylaxis is rare following the injection of hyaluronic acid fillers or human collagen for esthetic improvement of the face. We report a case occurring in a 63-year-old woman treated simultaneously with both. Symptoms included full-body urticaria and gastrointestinal symptoms that declined within a few hours, facial redness and swelling lasting a few days, and a nodule in the right tear trough that recurred over several months. Treatment with corticosteroids and antihistamine ultimately supported a complete recovery. Although rare, practitioners using injectables should be trained to manage anaphylactic events if they occur.

Increase in the incidence of acute inflammatory reactions to injectable fillers during COVID-19 era.

BACKGROUND: Acute inflammatory reactions (AIRs) are a rare complication following esthetic treatment with hyaluronic acid (HA) and/or human collagen fillers. However, a substantial increase in the frequency of AIRs was observed in the first author's clinic since May 2020. AIMS: To report AIR cases, we experienced and discuss potential underlying mechanisms. METHODS: This was a retrospective review of patients representing AIR symptoms following filler injection with HA or human collagen in our clinic. RESULTS: Although only one case of an AIR with an incidence rate of 0.01% was recorded following filler treatment between September 2008 and April 2020 in our clinic, we observed 14 AIR cases without anaphylaxis, with an incidence rate of 1.18% between May 2020 and June 2021, in line with the spreading of the new coronavirus pandemic. All cases were females aged 40-57 years, and the time of onset was within hours after filler injection. Three patients had been treated with HA fillers only, 2 with HA plus human collagen, and 9 with human collagen only. Most patients had been treated with these products in the past. Nine patients were treated with oral prednisolone. In all cases, symptoms resolved entirely within a week without sequelae. CONCLUSIONS: The marked increase in AIRs coincided with the COVID-19 pandemic. Possible explanations include immune system alterations caused by extensive changes in domestic and personal hygiene, prolonged and elevated stress levels, and subclinical COVID-19 infection. Further studies may be warranted.

Follicular dendritic cell-secreted protein gene expression is upregulated and spread in nifedipine-induced gingival overgrowth.

Follicular dendritic cell-secreted protein (FDC-SP) is secreted protein expressed in follicular dendritic cells, periodontal ligament and junctional epithelium (JE). Its expression could be controlled during inflammatory process of gingiva; however, responsible mechanism for gingival overgrowth and involvement of FDC-SP in clinical condition is still unclear. We hypothesized that JE-specific genes are associated with the initiation of drug-induced gingival enlargement (DIGE) called gingival overgrowth, and investigated the changes of JE-specific gene's expression and their localization in overgrown gingiva from the patients. Immunohistochemical analysis revealed that the FDC-SP localization was spread in overgrown gingival tissues. FDC-SP mRNA levels in GE1 and Ca9-22 cells were increased by time-dependent nifedipine treatments, similar to other JE-specific genes, such as Amelotin (Amtn) and Lamininß3 subunit (Lamß3), whereas type 4 collagen (Col4) mRNA levels were decreased. Immunocytochemical analysis showed that FDC-SP, AMTN, and Lamß3 protein levels were increased in GE1 and Ca9-22 cells. Transient transfection analyses were performed using luciferase constructs including various lengths of human FDC-SP gene promoter, nifedipine increased luciferase activities of -345 and -948FDC-SP constructs. These results raise the possibility that the nifedipine-induced FDC-SP may be related to the mechanism responsible for gingival overgrowth does not occur at edentulous jaw ridges.

Cerebellar swelling after sacrifice of the superior petrosal vein during microvascular decompression for trigeminal neuralgia.

The importance of preserving the deep cerebral venous outflow has been recognized in microvascular decompression for trigeminal neuralgia; however, few reports have described the details of complications arising from the sacrifice of the superior petrosal vein (SPV). During the procedure in a 77-year-old woman, some tributaries of the SPV complex were sacrificed to achieve microvascular decompression for right trigeminal neuralgia. Postoperatively, the patient was conscious and pain free; however, on postoperative day 1 she developed headache and nausea followed by a decreased level of consciousness. MRI revealed an extensive venous infarction in the right cerebellum. Sacrifice of the SPV may lead to serious, potentially life-threatening complications. Neurosurgeons should pay close attention to the management of the SPV to reduce the risk of venous complications.

Mechanical responses of a compliant electrospun poly(L-lactide-co-epsilon-caprolactone) small-diameter vascular graft.

To design a "mechano-active" small-diameter artificial vascular graft, a tubular scaffold made of elastomeric poly(L-lactide-co-epsilon-caprolactone) fabrics at different wall thicknesses was fabricated using an electrospinning (ELSP) technique. The wall thickness of the fabricated tube (inner diameter; approximately 2.3-2.5 mm and wall thickness; 50-340 microm) increased proportionally with ELSP time. The wall thickness dependence of mechanical responses including intraluminal pressure-induced inflation was determined under static and dynamic flow conditions. From the compliance-related parameters (stiffness parameter and diameter compliance) measured under static condition, the smaller the wall thickness, the more compliant the tube. Under dynamic flow condition (1 Hz, maximal/minimal pressure of 90 mmHg/45 mmHg) produced by a custom-designed arterial circulatory system, strain, defined as the relative increase in diameter per pulse, increased with the decrease in wall thickness, which approached that of a native artery. Thus, a mechano-active scaffold that pulsates synchronously by responding to pulsatile flow was prepared using elastomeric PLCL as a base material and an ELSP technique.