Space-Occupying Lesions of the Retropharyngeal Space: An Anatomical Study With Application to Postoperative Retropharyngeal Hematomas.

STUDY DESIGN: Cadaver study. OBJECTIVE: The retropharyngeal space's (RPS's) clinical relevance is apparent in anterior cervical spine surgery with respect to postoperative hematoma, which can cause life-threatening airway obstruction. This cadaver study aims to establish guidance toward a better understanding of the tolerance of the RPS to accommodate fluid accumulation. METHODS: Five fresh-frozen cadavers were dissected in the supine position. A digital manometer and a 20 Fr Foley catheter were inserted into the RPS via an anterolateral approach. While inflating the Foley catheter, the position of the esophagus/trachea was documented using fluoroscopy, and the retropharyngeal pressure was measured. We quantified the volume required to deviate the esophagus/trachea >1 cm from its original position using fluoroscopy. We also recorded the volume required to cause a visible change to the normal neck contour. RESULTS: A mean volume of 12.5 mL (mean pressure 1.50 mm Hg) was needed to cause >1 cm of esophageal deviation. Tracheal deviation was encountered at a mean volume of 20.0 mL (mean pressure of 2.39 mm Hg). External visible clinical neck contour changes were apparent at a mean volume of 39 mL. CONCLUSION: A relatively small volume of fluid in the RPS can cause the esophagus/trachea to radiographically deviate. The esophagus is the structure in the RPS to be most influenced by mass effect. The mean volume of fluid required to cause clinically identifiable changes to the normal neck contour was nearly double the volume required to cause 1 cm of esophageal/tracheal deviation in a cadaver model.

Chordae Willisii Within the Transverse Sinus: Morphologic Study.

OBJECTIVE: Some have suggested that trabeculae within the transverse sinuses (chordae Willisii) might restrict flow and potentially contribute to thrombus organization. In addition, these structures might be encountered with endovascular procedures within the transverse sinus and are now readily seen on imaging. Therefore as anatomic studies of these structures are scant, the current study aimed to better elucidate these structures within the transverse sinus via a morphologic study in cadavers. METHODS: Thirty fresh-frozen, cadaveric transverse sinuses were dissected, and their detailed morphology was recorded. Classification schemes were applied based on the anatomy and orientation of each chordae. RESULTS: Chordae were found on 70% of sides and were statistically more likely to be found on right sides (86.6%) (P < 0.01). Three types and 3 classes of chordae were identified. There was a statistically significant difference between sides regarding type of chordae (P = 0.02). CONCLUSIONS: To date, a comprehensive anatomic evaluation of the intraluminal chordae of the transverse sinuses has been lacking. Knowledge of these bands is also essential to those performing endovascular procedures of the dural venous sinuses and for those interpreting imaging of these structures.

Surgical anatomy of the internal carotid plexus branches to the abducens nerve in the cavernous sinus.

OBJECTIVE: Sympathetic branches to the abducens nerve derived from the internal carotid artery sympathetic plexus, while in the cavernous sinus, have been scantly described in the extant literature. Therefore, the present cadaveric study was performed to better elucidate this anatomy. PATIENTS AND METHODS: Eighteen cadaveric sides underwent dissection. RESULTS: The number of branches derived from the sympathetic plexus traveling with the internal carotid artery in the cavernous sinus was one on 11.1 %, two in 11.1 %, and three in 72.2 %. One side was found to have no branches (5.6 %). The mean diameter of the distance from the posterior border of the internal carotid artery, length, and diameter of the branches was 7.0 ±â€¯4.1 mm, 2.9 ±â€¯1.3 mm, and 0.4 ±â€¯0.1 mm, respectively. Of 44 of 45 sympathetic branches, 97.8 % originated from the lateral wall of the cavernous part of the internal carotid artery with only one from the medial wall. CONCLUSION: Based on our cadaveric findings, sympathetic connections between the internal carotid artery and the abducens nerve are common. Therefore, surgeons who operate in or near the cavernous sinus should be aware of such connections in order not to place unwanted tension on the cavernous part of the internal carotid artery or abducens nerve during dissection.

Air dissection of the spaces of the head and neck: A new teaching and dissection method.

Our goal was to evaluate a new air dissection technique for the spaces of the head and neck using fresh-frozen cadavers. Eight sides from four fresh-frozen Caucasian cadavers were used in this study. Compressed air was initially placed into the pterygomandibular space while simultaneously observing the spaces of the head and neck. Subsequently, the pterygomandibular space on the contralateral side of the specimen was insufflated and observations made. For these methods, simultaneous observation of mediastina and lungs was made using intrathoracic endoscopy. On all sides, the buccal, submental, sublingual, parotid, parapharyngeal, and retropharyngeal spaces were insufflated on both ipsilateral and contralateral sides. Deviation of the larynx and trachea was observed externally and deviation of the mediastinum and lungs via intrathoracic endoscopy. We introduced air dissection into spaces of the head and neck. This new technique might help students, teachers, dentists, medical doctors, and other healthcare providers to better understand the three-dimensional anatomy of the spaces of the head and neck and their communicating pathways. Clin. Anat. 33:207-213, 2020. © 2019 Wiley Periodicals, Inc.

Microsurgical Anatomy of the Superior Wall of the Mandibular Canal and Surrounding Structures: Suggestion for New Classifications for Dental Implantology.

Our goal was to clarify the relationship between the superior wall of the mandibular canal and the presence of teeth. We also sought to study the structural changes of the mandibular canal after tooth loss. Twenty sides from 10 dry mandibles derived from six males and four females were used for this study. The age of the specimens at the time of death ranged from 57 to 91 years. The mandibles were cut in the midline resulting in 20 hemi-mandibles. The presence of teeth (from the second premolar to the third molar) was recorded for each hemi-mandible. The mandibular canal in the body of the mandible was divided into four areas, that is, Areas 1-4. The superior wall of the mandibular canal and a cancellous bone pattern above the mandibular canal were observed. Next, the mandibular canal was horizontally cut at its center and the superior wall of the mandibular canal observed inferiorly. A total of 75 areas (20 dentulous areas and 55 edentulous areas) were produced. The distal view was classified into three groups, Type I (trabecular pattern), Type II (osteoporotic pattern), and Type III (dense/irregular pattern). The Type I pattern was found in 60.0% (12/20) of the dentulous areas and 32.7% of the edentulous areas. While the Type II pattern was found in 15.0% (23/55) of the dentulous areas and 41.8% of the edentulous areas. The inferior view was classified into four groups depending on the surface of the superior wall of the mandibular canal, that is, Class I (trabecular pattern), Class II (osteoporotic pattern), Class III (dense/irregular pattern), and Class IV (smooth).The Class I pattern was seen most frequently (55.0%) in dentulous areas and the Class IV pattern (45.5%) most frequently in edentulous areas. Based on these results, we conclude that the superior wall of the mandibular canal could change following tooth loss. Clin. Anat. 33:223-231, 2020. © 2019 Wiley Periodicals, Inc.