SciCombinator

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Concept: Mastoid process

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OBJECTIVE The occipital artery (OA) is a frequently used donor vessel for posterior circulation bypass procedures due to its proximity to the recipient vessels and its optimal caliber, length, and flow rate. However, its tortuous course through multiple layers of suboccipital muscles necessitates layer-by-layer dissection. The authors of this cadaveric study aimed to describe a landmark-based novel anterograde approach to harvest OA in a proximal-to-distal “inside-out” fashion, which avoids multilayer dissection. METHODS Sixteen cadaveric specimens were prepared for surgical simulation, and the OA was harvested using the classic (n = 2) and novel (n = 14) techniques. The specimens were positioned three-quarters prone, with 45° contralateral head rotation. An inverted hockey-stick incision was made from the spinous process of C-2 to the mastoid tip, and the distal part of the OA was divided to lift up a myocutaneous flap, including the nuchal muscles. The OA was identified using the occipital groove (OG), the digastric muscle (DM) and its groove (DG), and the superior oblique muscle (SOM) as key landmarks. The OA was harvested anterogradely from the OG and within the flap until the skin incision was reached (proximal-to-distal technique). In addition, 35 dry skulls were assessed bilaterally (n = 70) to study additional craniometric landmarks to infer the course of the OA in the OG. RESULTS The OA was consistently found running in the OG, which was found between the posterior belly of the DM and the SOM. The mean total length of the mobilized OA was 12.8 ± 1.2 cm, with a diameter of 1.3 ± 0.1 mm at the suboccipital segment and 1.1 ± 0.1 mm at the skin incision. On dry skulls, the occipitomastoid suture (OMS) was found to be medial to the OG in the majority of the cases (68.6%), making it a useful landmark to locate the OG and thus the proximal OA. CONCLUSIONS The anterograde transperiosteal inside-out approach for harvesting the OA is a fast and easy technique. It requires only superficial dissection because the OA is found directly under the periosteum throughout its course, obviating tedious layer-by-layer muscle dissection. This approach avoids critical neurovascular structures like the vertebral artery. The key landmarks needed to localize the OA using this technique include the OMS, OG, DM and DG, and SOM.

Concepts: Heart, Skull, Harvest, Vertebra, Superior oblique muscle, Atlas, Digastric muscle, Mastoid process

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This paper proposes a method for the quantification of the shape of sexually dimorphic cranial traits, namely the glabella, mastoid process and external occipital protuberance.

Concepts: Scientific method, Sexual dimorphism, Sex, Bones of the head and neck, Mastoiditis, Inion, Mastoid process, External occipital protuberance

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The main objective of this study was to measure the vibrotactile thresholds on the mastoid process and forehead positions using patients with bilateral deafness and to compare the results from the two bone conduction vibrators Radioear B71 and B81.

Concepts: Hearing impairment, Otology, Mastoid process

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To evaluate and compare clinical and microbiological findings in adults hospitalized for acute otitis media (AOM) or mastoid infections (acute or latent).

Concepts: Infection, Inflammations, Otitis media, Otitis externa, Mastoiditis, Mastoid process

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The aim of the study described here was to evaluate experience in the diagnosis of a subperiosteal abscess secondary to mastoiditis by means of ultrasound. Ten consecutive cases in which an ultrasound examination of the retro-auricular region was performed for suspected mastoiditis were identified. In nine cases, we found a poorly demarcated, inhomogeneous, irregular, poorly perfused lesion abutting the outer table of the cranial vault, with elevation of the outer periosteum and a clearly delineated defect of the cortical layer. In one case, there was additional invasion of the insertion of the sternocleidomastoid muscle on the mastoid process of the temporal bone, raising the suspicion of Bezold mastoiditis. Ultrasound may help in selecting patients for further imaging and might spare computer tomography, especially in sensitive patient groups such as children and pregnant women, if a defect of the outer cortex of the temporal bone can be excluded with certainty.

Concepts: Pregnancy, Medical imaging, Cerebral cortex, Skull, Medical ultrasonography, Cortical column, Mastoiditis, Mastoid process

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We found that the great auricular nerve (GAN) passes at the median (m) point between the tips of the mandibular angle and mastoid process. We also established the GAN definitive line using this point for rapid identification of the trunk of the GAN and systematic parotidectomy combined with procedures for identification of the GAN, elevation of the skin flap, and exposure of the parotid capsule, which showed a high rate of preservation of the nerve and the lobular branch.

Concepts: Skin, Cranial nerves, Branch, Great auricular nerve, Digastric muscle, Mastoiditis, Mastoid process

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Abstract Conclusion: A 20 mm hole made backwards from the midpoint of the asterion to the mastoid process is suitable for a retrosigmoid keyhole approach with the aid of an endoscope. The endoscope-assisted retrosigmoid keyhole approach can be considered an effective and safe method for removal of vestibular schwannoma. Objective: To investigate the feasibility of the endoscope-assisted retrosigmoid keyhole approach for exposing the cerebellopontine angle (CPA) and internal auditory canal (IAC). Methods: With the aid of an endoscope, we simulated surgical procedures in 30 sides of 15 formalin-fixed cadaver heads. Results: (1) For 24 (80%) sides, the midpoint of the top notch to the mastoid process was in the anterior edge of the sigmoid sinus; for 27 sides (90%) the midpoint of the asterion to the mastoid process was in the posterior edge of the sigmoid sinus. (2) The IAC and CPA were exposed by the retrosigmoid keyhole approach with the aid of the endoscope.

Concepts: Surgery, Vestibular schwannoma, Schwannoma, Digastric muscle, Mastoiditis, Internal auditory meatus, Mastoid process

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Mastoiditis is a common clinical entity that is technically present in all cases of otitis media; only a minority of cases actually represents the otolaryngologic emergency of acute coalescent mastoiditis. When reviewing an image with a radiologic diagnosis of mastoiditis, looking for key signs such as destruction of bony septa and considering patient presentation can help distinguish mild mastoiditis from acute coalescent mastoiditis.

Concepts: Inflammations, Otitis media, Mastoiditis, Mastoid process