The Posterior Auricularis Muscle as Superficial Landmark for the Sigmoid Sinus and Transverse-Sigmoid Sinus Junction: An Anatomical Study.

OBJECTIVE: Neuronavigation systems coupled with previously reported external anatomical landmarks assist neurosurgeons during intracranial procedures. We aimed to verify whether the posterior auricularis muscle (PAM) could be used as an external landmark for identifying the sigmoid sinus (SS) and the transverse-sigmoid sinus junction (TSSJ) during posterior cranial fossa surgery. METHODS: The PAM was dissected in 10 adult cadaveric heads and after drilling the underlying bone, the relationships with the underlying SS and TSSJ were noted. The width and length of the PAM, and the distance between the muscle and reference points (asterion, mastoid tip, and midline), were measured. RESULTS: The PAM was identified in 18 sides (9 left, 9 right). The first 20 mm of the muscle length (mean 28.28 mm) consistently overlay the mastoid process anteriorly and the proximal half of the SS slightly posteriorly on all sides. The superior border was a mean of 2.22 mm inferior to the TSSJ and, especially when the muscle length exceeded 20 mm, this border extended closer to the transverse sinus; it was usually found at a mean of 3.11 mm (range 0.0-13.80 mm) inferior to the distal third of the transverse sinus. CONCLUSIONS: Superficial landmarks give surgeons improved surgical access, avoiding overexposure of deep neurovascular structures and reducing brain retraction. On the basis of our cadaveric study, the PAM is a reliable and accurate direct landmark for identifying the SS and TSSJ. The PAM could potentially be used for guiding the retrosigmoid approach.

An anatomical study of the sigmoid sinus artery: Application to the transmastoid approach.

INTRODUCTION: We aimed to investigate the morphological features of the artery that traverse the sigmoid sinus's lateral surface and to discuss this structure's clinical relevance. METHODS: Ten sides from five cadaveric Caucasian heads were used for gross anatomical dissection to investigate the morphological features of the sigmoid sinus artery (SSA), and additional five sides were used for histological observation. RESULTS: The SSA was found on eight out of ten sides (80%). The mean diameter of the SSA was 0.3 mm. The mean distance from the tip of the mastoid process to the artery was 20.3 mm. Histological observation identified extradural and intradural courses of SSA. The intradural course was further categorized into protruding and non-protruding types. In the protruding type, the SSA traveled within the dura but indented into the bone, making it more or less an intraosseous artery. In the non-protruding type, the SSA traveled within the dura but did not protrude into the bone but rather indented into the lumen of the SS. In all sections, both intradural and extradural courses were identified simultaneously. CONCLUSIONS: When the mastoid foramen is observed, it does not always only carry an emissary vein but also an artery. The SSA could be considered a "warning landmark" during bone drilling for the transmastoid approach.

Epiglottic Epidermoid Cyst: Cadaveric Case Report and Clinical-Surgical Applications.

An epidermoid cyst is lined with stratified squamous epithelium with a lumen filled with fluid, in most cases. Such cysts can occur anywhere in the body; however, they are rarely found on the epiglottis (0.54%). Herein, we describe to our knowledge, the first cadaveric case of a regular, circular, and soft mass extending out from the tip of the epiglottis with consistent histological characteristics of an epidermoid cyst. Epiglottic cysts are rare and mostly asymptomatic. However, through this case report, we aimed to highlight the clinical-surgical applications presented mainly when they grow large enough, to cause issues with ventilation or obstruct endotracheal tubes, thus interfering with airway management. Additionally, such cysts can affect swallowing or speaking.

The sublingual branch of the lingual nerve: Anatomical study and suggestion for a new terminology.

The lingual nerve carries somatosensory fibers from the anterior two-thirds of tongue. The parasympathetic preganglionic fibers arising from the chorda tympani also travel with the lingual nerve in the infratemporal fossa to synapse in the submandibular ganglion to innervate the sublingual gland. However, only a few studies have investigated the specific nerve that innervates the sublingual gland and surrounding tissue i.e., the so-called sublingual nerve. Therefore, this study aimed to clarify the anatomy and definition of the sublingual nerves. Thirty sides from formalin fixed cadaveric hemiheads underwent microsurgical dissection of the sublingual nerves. The sublingual nerves were found on all sides and categorized into three branches, i.e., branches to the sublingual gland, branches to the mucosa of the floor of the mouth, and gingival branches. Additionally, branches to the sublingual gland were subcategorized into types I and II based on the origin of the sublingual nerve. We suggest that the lingual nerve branches should be categorized into five branches, i.e., branches to the isthmus of the fauces, sublingual nerves, lingual branches, posterior branch to the submandibular ganglion, and branches to the sublingual ganglion.

Transosseous Veins of the Temporal Bone: Connection Between Middle and Posterior Cranial Fossa Venous Structures.

BACKGROUND: The veins and dural venous sinuses of the skull base are important to understand in terms of imaging findings, diagnoses, and surgery. However, to date and to the best of our knowledge, the transosseous veins of the petrous part of the temporal bone have not been studied. METHODS: Ten latex-injected adult cadaveric specimens (20 sides) were dissected to identify the intraosseous and transosseous veins. The petrous part of the temporal bone was drilled away, and the petrous part of the internal carotid artery and the veins of the middle and posterior cranial fossa adjacent to the petrous part of the temporal bone were exposed. RESULTS: Transosseous veins traveling through the petrous part of the temporal bone were identified on all 20 sides. In general, these were most concentrated near the anterior and posterior parts of the petrous part of the temporal bone. Most traveled more or less vertically from the petrous ridge and related superior petrosal sinus internally through the petrous part of the temporal bone toward the inferior petrosal sinus or horizontally, uniting the veins of the floor of the middle cranial fossa with the veins of the posterior cranial fossa. These transosseous veins connected the veins in the middle cranial fossa with the veins of the posterior cranial fossa. Most (70%) of these transosseous veins were also found to have small connections to the internal carotid venous plexus. CONCLUSIONS: To the best of our knowledge, previous studies have not reported on transosseous veins of the temporal bone or described their anatomy of connecting the veins of the middle and posterior cranial fossae.

Middle Fossa Encephaloceles Treated via the Transmastoid Approach: A Case Series and Review of the Literature.

BACKGROUND: Middle fossa (MF) encephaloceles are rare lesions resulting from herniation through defects in the tegmen tympani or mastoideum. Underlying etiologies and clinical presentations are variable. Surgical goals include fistula obliteration, resection of nonfunctioning parenchyma, and dehiscence repair. The middle cranial fossa approach (MCFA), transmastoid approach (TMA), and combined (MCFA + TMA) approaches have been described. The minimally invasive TMA provides excellent exposure of the pathology and allows for ample working room to repair the defect. OBJECTIVE: To present short-term follow-up results in patients treated via the TM repair at our institution. METHODS: A retrospective review of patients with symptomatic encephaloceles treated via the TMA by our multidisciplinary team. Patient demographics, clinical presentations, intraoperative findings, repair technique, and outcomes were highlighted. RESULTS: A total of 16 encephaloceles in 13 patients were treated. Defect etiologies included spontaneous (50.0%), secondary to chronic infection (25.0%), or cholesteatoma (18.8%). Defects were most often within the tegmen mastoideum (68.8%). Average length of surgery was 3.3 h (95% CI: 2.86-3.67) and length of stay 3.9 d (95% CI: 3.09-4.79). On short-term follow-up (average 11.5 mo), no patients experienced postoperative cerebrospinal fluid leak or recurrence. The majority of patients (83.3%) experienced confirmed improvement or stabilization of hearing. CONCLUSION: MF encephaloceles present with various clinical manifestations and result from multiple underlying etiologies. The TMA is an alternative to craniotomy and our short-term results suggest that this approach may be utilized effectively in appropriately selected cases.

Incidence of Developing Contralateral Ménière's Disease in Patients Undergoing Transmastoid Labyrinthectomy for Unilateral Ménière's Disease.

OBJECTIVES: To analyze the incidence of developing contralateral Ménière's disease (MD) in patients who undergo labyrinthectomy for vestibular dysfunction in unilateral MD. STUDY DESIGN: Retrospective chart review. PARTICIPANTS AND METHODS: Adult patients with a diagnosis of MD who underwent surgical labyrinthectomy with minimum follow-up of 12 months were included. Patients who experienced chemical labyrinthectomy, surgical labyrinthectomy for a diagnosis other than MD, contralateral ear surgery, or bilateral MD before the labyrinthectomy were excluded. The key outcome measure is whether symptoms of MD developed in the contralateral ear post-labyrinthectomy. Statistical analysis was performed using χ2 (Fisher exact) test for discrete variables and the Student t test for continuous variables. A P value < .05 was considered significant. RESULTS: Of the140 patients who underwent labyrinthectomy for intractable vertigo due to unilateral MD, 84 had at least 1 year follow-up appointments. Twelve percent (10/84) of these patients developed contralateral MD, which was diagnosed by a neuro-otologist based on symptoms consistent with MD, including low-frequency sensorineural hearing loss. Average age in years is 63.12 (10.83; mean [SD]) at time of surgery. Average follow-up was 35.57 (15.89) months (range: 12-69 months). CONCLUSION: The incidence of contralateral MD development in patients who underwent labyrinthectomy for unilateral MD is 12%. The current literature states that MD has a 30% bilateral involvement rate. Our incidence is significantly lower when compared to the current literature.

Diagnostic yield of MRI of the brain and IAC in patients with neurotologic complaints.

OBJECTIVES: Quantify number of MRI scans obtained in a tertiary neurotology practice and identify likelihood of pathologic findings. STUDY DESIGN: Retrospective cohort study. SETTING: Tertiary neurotology center. SUBJECTS AND METHODS: A retrospective analysis of all adult patients over 20 months (3/2012-10/2013) where MRI was deemed necessary for evaluation of neurotologic complaints. Demographics, clinical history, physical examination, and audiometric findings were used to categorize new patients into 7 groups: definite Meniere's disease (MD), probable MD, possible MD, vague dizziness, tinnitus only, asymmetric hearing loss (HL), and other symptoms to stratify risk for retrocochlear tumor and other relevant pathology. RESULTS: 1537 MRI scans were performed, 932 of these were for a new diagnosis. Discovering retrocochlear tumors was rare (1.4%). Patients with HL had a 0.3% (1/314) chance of retrocochlear tumor and 3.2% (10/314) chance of relevant pathology. Patients with only unilateral tinnitus had no evidence of retrocochlear tumors, and 3.8% chance of finding relevant pathology. Patients with "definite" or "probable" MD had no evidence of retrocochlear tumor or other relevant findings. All discovered acoustic neuromas were in the "possible MD" category, which had a 9.3% chance of finding all relevant pathology. CONCLUSIONS: In a tertiary neurotology center, the likelihood of finding a retrocochlear tumor on MRI is rare. In the current study, unilateral tinnitus exclusively, "definite MD," and "probable MD" failed to yield a single example of retrocochlear tumor. Patients with "possible MD" had the highest probability of finding retrocochlear tumors and other relevant pathology.

Hydroxyapatite cement cranioplasty following translabyrinthine approach: Long-term study of 369 cases.

OBJECTIVE: To report the authors' experience with hydroxyapatite cement (HAC) cranioplasty and analyze the material's long-term safety and efficacy in repairing translabyrinthine skull-base defects by examining adverse events, specifically cerebrospinal fluid (CSF) leaks and surgical site infections. STUDY DESIGN: Retrospective case-control study (primary study arm); prospective cross-sectional study of patients not examined within the last 5 years (secondary arm). SETTING: tertiary-care neurotology private practice and academic practice (two centers). METHODS: Hydroxyapatite cement implanted following translabyrinthine approach, with or without fat graft, was included. Combined approaches were excluded. Implant-associated adverse events were defined as 1) CSF leaks requiring reoperation or spinal drainage, and (2) infections requiring reoperation. Patients not examined within 5 years were interviewed by telephone to update their condition. Incidence of adverse events was compared to published data for translabyrinthine cranioplasty using fat graft alone. Implant survival analysis was performed. RESULTS: The study cohort included 369 HAC implants in the same number of patients. There were seven CSF leaks and seven infections. Combined (n = 14) incidence of adverse events was 3.8% (2.09%, 6.28%). Compared to fat graft alone, the adverse events associated with HAC were fewer (P < 0.001). Up to 15 years (5,475 days), HAC cement maintained 95% adverse event-free survival. There were no cases of meningitis. CONCLUSION: Cranioplasty using HAC with autologous fat following translabyrinthine skull-base surgery is safer and more effective than fat graft alone, up to 15 years after surgery. LEVEL OF EVIDENCE: 4. Laryngoscope, 127:2120-2125, 2017.

Is MRI Equal to CT in the Evaluation of Thin and Dehiscent Superior Semicircular Canals?

OBJECTIVE: Can magnetic resonance imaging (MRI) diagnose abnormally thin and dehiscent superior semicircular canals (SSCs) that traditionally rely on evaluation by computed tomography (CT) imaging? STUDY DESIGN: Retrospective clinical study. SETTING: Tertiary referral center. PATIENTS: Adults who underwent both MRI and CT of the temporal bones over the past 3 years. INTERVENTIONS: CT and MR images of SSCs were separately reviewed, in a blinded fashion by three neuroradiologists at our institution. CT diagnosis of abnormally thin or dehiscent SSC was used as the "gold" standard. MAIN OUTCOME MEASURES: 1) Dehiscent SSC. 2) Abnormally thin SSC. 3) Normal SSC. RESULTS: One hundred temporal bones with evaluable superior semicircular canals from 51 patients were eligible for review on CT and MR imaging. There were 26 patients of thin SSC and 17 patients of SSC dehiscence on CT imaging, of which 13 and 15 respectively were also found on MRI. There were nine false-positive dehiscent SSC patients and four thin SSC patients observed on MR imaging while not observed on CT. For thin SSCs, MRI sensitivity was 61.9% and specificity of 94.3% with a positive predictive value of 81.3% and a negative predictive value of 86.2%. For dehiscent SSCs, sensitivity was 88.2% and specificity of 89.2% with a positive predictive value of 62.5% and a negative predictive value of 97.4%. CONCLUSION: In this series, MRI in the axial and coronal plane had a high negative predicative value for thin SSC (86%) and dehiscent SSC (97%). However, MRI cannot conclusively diagnose thin or dehiscent SSCs.

Does electrocautery damage cochlear implants?

OBJECTIVES: 1) Evaluate the effects of monopolar cautery on cochlear implant devices. 2) Determine whether voltage fluctuations within the cochlear implant adversely affect the cochlear implant devices STUDY DESIGN: Two Med-El cochlear implants modified to record voltage difference from the apical and proximal electrodes were implanted into an unembalmed, fresh cadaver. Cautery was applied to the ipsilateral pectoralis major muscle and ipsilateral temporalis muscle at bipolar, monopolar coagulation, and monopolar cut settings of 50 W. The intensity in each modality setting was increased by increments of 10 W to a maximum of 100 W. Integrity testing was performed before, during, and after each cautery setting. Voltage fluctuations were measured during cautery, and maximal voltage changes for each setting were noted. After explantation, devices were returned to the manufacturer for in-depth failure analysis to evaluate for any damage to the devices. SETTING: Tertiary medical center. SUBJECTS: Cadaveric study. METHODS: Basic science laboratory. RESULTS: No change in impedance or integrity testing occurred at any cautery setting when applied to either to pectoralis major or temporalis. The maximum voltage change was 22 V. Comprehensive device analysis showed no evidence of device damage from the study. CONCLUSIONS: The cochlear implant devices had no evidence of electrical damage by monopolar cautery, even up to levels of 100 W in the temporalis muscle. The maximum voltage change was 22 V, likely resulting from protecting diodes within the implant. Additional study is necessary, but more flexible recommendations regarding electrosurgery in cochlear implant recipients should be considered.

Cochlear trajectory in pediatric patients.

OBJECTIVES/HYPOTHESIS: As cochlear implantation increases, surgeons are noting possible anatomical differences in pediatric population. Outcome objectives were to study pediatric temporal bone anatomy using high-resolution temporal bone imaging, and analyze the anatomical differences in group 1 (<12 months) versus group 2 (1-4 years) versus group 3 (5-10 years) versus group 4 (10-18 years). STUDY DESIGN: Retrospective chart and radiologic review. METHODS: A retrospective chart and radiologic review of pediatric patients undergoing high-resolution computer tomography of the temporal bones from April 2001 to February 2013 was conducted. Scans were reviewed to record the transmastoid angle and transcanal angle. RESULTS: Seven hundred fifty patients were identified. A total of 1,426 ears were reviewed. The age range was 8 days to 21 years. Of the patients, 57.0% (n = 407) were male. The patients were divided into four groups: group 1 (<12 months), group 2 (1-4 years), group 3 (5-10 years), and group 4 (10-18 years). The transmastoid angle was observed to have variability. Significant differences were observed between groups 2 and 3 (P = .0028) and groups 2 and 4 (P = .0432). Analysis on the transcanal angle was performed. Significant differences existed between age groups 1 and 3 (P = .0150), groups 1 and 4 (P = .0038), and groups 2 and 4 (P = .0358). CONCLUSIONS: Considerable variation exists in pediatric temporal bones. The largest difference in the transmastoid angle was seen in children aged 1 to 4 years. The largest variability in the transcanal angle is between the infant (<12 months) and children >4 years of age. These differences are surgically relevant for round window identification and facial nerve safety during cochlear implant surgery in infants.

The relationship of age and radiographic incidence of superior semicircular canal dehiscence in pediatric patients.

OBJECTIVE: To determine if age affects radiographic incidence of superior semicircular canal dehiscence (SSCD) in pediatric patients. STUDY DESIGN: Retrospective case review. SETTING: Tertiary children's hospital. PATIENTS: Patients (0-18 yr) with high-resolution computed tomography (CT) temporal bone scans from April 2001 to February 2013. INTERVENTIONS: Diagnostic high-resolution CT temporal bone scans. MAIN OUTCOME MEASURES: Findings of dehiscent, thin, or normal SSC on CT scans (including reconstructed Poschl views). Interobserver radiographic interpretation rate between neuroradiologist and otologist. RESULTS: Seven-hundred CT scans (1,400 ears) were reviewed, and 1,188 ears were acceptable for analysis. Twenty-three ears (1.9%) had dehiscent SSC, 185 ears (15.6%) had thin SSC, and 980 ears (82.5%) had normal SSC. Median ages of dehiscent, thin, and normal canals were 5, 7, and 9 years, respectively ( p < 0.05). As age increased, the incidence of dehiscent and thin SCC cases decreased; for example, dehiscent or thin canal existed in 51.4% of children less than 12 months, 17.5% of children between 1 and 2 years, 18.5% of children between 3 and 10 years, and 10.9% of children between 11 and 18 years. The κ value of agreement between neuroradiologist and otologist was 0.814, demonstrating a high value of agreement (p < 0.05). CONCLUSION: Radiographic SSCD, although uncommon, appears to be more prevalent in younger children, especially infants younger than 12 months. This suggests that the SSC may develop more bony covering with age.

The Hubble Constant.

I review the current state of determinations of the Hubble constant, which gives the length scale of the Universe by relating the expansion velocity of objects to their distance. There are two broad categories of measurements. The first uses individual astrophysical objects which have some property that allows their intrinsic luminosity or size to be determined, or allows the determination of their distance by geometric means. The second category comprises the use of all-sky cosmic microwave background, or correlations between large samples of galaxies, to determine information about the geometry of the Universe and hence the Hubble constant, typically in a combination with other cosmological parameters. Many, but not all, object-based measurements give H0 values of around 72-74 km s-1 Mpc-1, with typical errors of 2-3 km s-1 Mpc-1. This is in mild discrepancy with CMB-based measurements, in particular those from the Planck satellite, which give values of 67-68 km s-1 Mpc-1 and typical errors of 1-2 km s-1 Mpc-1. The size of the remaining systematics indicate that accuracy rather than precision is the remaining problem in a good determination of the Hubble constant. Whether a discrepancy exists, and whether new physics is needed to resolve it, depends on details of the systematics of the object-based methods, and also on the assumptions about other cosmological parameters and which datasets are combined in the case of the all-sky methods.

Facial swelling in a sickle cell patient.

Sickle cell disease (SCD) is characterized as a chronic hemolytic anemia with vaso-occlusive crises that result in multisystem organ damage. Bone marrow is one of the more common sites of these crises, presumably due to marrow hypercellularity that impairs blood flow- leading to regional hypoxia and subsequent infarction. Infarcts of facial bones are considered an uncommon complication of SCD. When infarcts occur in facial bones, the mandible and orbital bones are the most commonly affected. Overall, the clinical presentation of facial bone infarctions may mimic an infectious process, such as cellulitis, an abscess, or, more commonly, osteomyelitis. The purpose of this paper was to present the case of a patient with a confluence of symptoms in the face as a result of her sickle cell disease.

The Hubble Constant.

I review the current state of determinations of the Hubble constant, which gives the length scale of the Universe by relating the expansion velocity of objects to their distance. In the last 20 years, much progress has been made and estimates now range between 60 and 75 km s-1 Mpc-1, with most now between 70 and 75 km s-1 Mpc-1, a huge improvement over the factor-of-2 uncertainty which used to prevail. Further improvements which gave a generally agreed margin of error of a few percent rather than the current 10% would be vital input to much other interesting cosmology. There are several programmes which are likely to lead us to this point in the next 10 years.