Tandem cranial and spinal cerebrospinal fluid leaks presenting with otogenic tension pneumocephalus: illustrative case.

BACKGROUND: Cranial and spinal cerebrospinal fluid (CSF) leaks are associated with opposite CSF fluid dynamics. The differing pathophysiology between spontaneous cranial and spinal CSF leaks are, therefore, mutually exclusive in theory. OBSERVATIONS: A 66-year-old female presented with tension pneumocephalus. The patient underwent computed tomography (CT) scanning, which demonstrated left-sided tension pneumocephalus, with an expanding volume of air directly above a bony defect of the tegmen tympani and mastoideum. The patient underwent a left middle fossa craniotomy for repair of the tegmen CSF leak. In the week after discharge, she developed a recurrence of positional headaches and underwent head CT. Further magnetic resonance imaging of the brain and thoracic spine showed bilateral subdural hematomas and multiple meningeal diverticula. LESSONS: Cranial CSF leaks are caused by intracranial hypertension and are not associated with subdural hematomas. Clinicians should maintain a high index of suspicion for intracranial hypotension due to spinal CSF leak whenever "otogenic" pneumocephalus is found. Close postoperative follow-up and clinical monitoring for symptoms of intracranial hypotension in any patients who undergo repair of a tegmen defect for otogenic pneumocephalus is recommended.

Anatomic Assessment of the Limits of an Endoscopically Assisted Retrolabyrinthine Approach to the Internal Auditory Canal.

Objective Data regarding the surgical advantages and anatomic constraints of a hearing-preserving endoscopic-assisted retrolabyrinthine approach to the IAC are scarce. This study aimed to define the minimum amount of retrosigmoid dural exposure necessary for endoscopic exposure of the IAC and the surgical freedom of motion afforded by this approach. Methods Presigmoid retrolabyrinthine approaches were performed on fresh cadaveric heads. The IAC was exposed under endoscopic guidance. The retrosigmoid posterior fossa dura was decompressed until the fundus of the IAC was exposed. Surgical freedom of motion at the fundus was calculated after both retrolabyrinthine and translabyrinthine approaches. Results The IAC was entirely exposed in nine specimens with a median length of 12 mm (range: 10-13 mm). Complete IAC exposure could be achieved with 1 cm of retrosigmoid dural exposure in eight of nine mastoids. For the retrolabyrinthine approach, the median anterior-posterior surgical freedom was 13 degrees (range: 6-23 degrees) compared with 46 degrees (range: 36-53 degrees) for the translabyrinthine approach ( p = 0.014). For the retrolabyrinthine approach, the median superior-inferior surgical freedom was 40 degrees (range 33-46 degrees) compared with 47 degrees (range: 42-51 degrees) for the translabyrinthine approach ( p = 0.022). Conclusion Using endoscopic assistance, the retrolabyrinthine approach can expose the entire IAC. We recommend at least 1.5 cm of retrosigmoid posterior fossa dura exposure for this approach. Although this strategy provides significantly less instrument freedom of motion in both the horizontal and vertical axes than the translabyrinthine approach, it may be appropriate for carefully selected patients with intact hearing and small-to-medium sized tumors involving the IAC.

Hypercoagulability in Vestibular Schwannoma Surgery.

OBJECTIVE: Patients with vestibular schwannoma who harbor a genetic predisposition for venous thromboembolism require special consideration when determining optimal therapeutic management. The primary objective of the current study was to provide recommendations on treatment of hypercoagulable patients with vestibular schwannoma through a case series and review of the literature. PATIENTS: Two patients who underwent resection of vestibular schwannomas. INTERVENTIONS: Surgical resection and diagnostic testing. MAIN OUTCOME MEASURES: Postoperative venous thromboses. RESULTS: One patient who underwent resection of vestibular schwannoma and suffered several postoperative thrombotic complications consistent with a clinical thrombophilia. One patient with known Factor V Leiden deficiency who underwent resection of vestibular schwannoma followed by postoperative chemoprophylaxis with a direct factor Xa inhibitor and experienced an uneventful postoperative course. CONCLUSIONS: In patients with a known propensity for venous thromboembolism, the skull base surgeon should consider nonsurgical management. If the patient undergoes surgical resection, we recommend careful effort to minimize trauma to the sigmoid sinus. In addition, the surgeon may consider retrosigmoid or middle fossa approaches. Best practice recommendations include the use of pneumatic compression devices, early ambulation, and consideration of postoperative prophylactic anticoagulation in patients with a known genetic predisposition.

Internal Auditory Canal Diverticula in Children: A Congenital Variant.

OBJECTIVES/HYPOTHESIS: Internal auditory diverticula in adults have been found to exist independent of otosclerosis, and in the presence of otosclerosis. We sought to determine the prevalence of internal auditory canal (IAC) diverticula in a pediatric cohort, to assess whether IAC diverticula are a risk factor for hearing loss, and the co-occurrence of otic capsule hypoattenuation. STUDY DESIGN: Retrospective review. METHODS: A single-site retrospective review of high-resolution temporal bones computed tomography (CT) scans including the presence and size of diverticula and hypoattenuation of the otic capsule. Demographic, imaging, and audiometric data were collected and descriptively analyzed. Bivariate analysis of collected variables was conducted. Comparisons between sides in unilateral cases were also performed. RESULTS: 16/600 (2.7%; 95% CI [2.0%, 3.4%]) were found to have IAC diverticula. Six were bilateral. Thirty-one patients (5.2%) were found to have hypoattenuation of the otic capsule. There were no coincident cases of IAC diverticulum and hypoattenuation of the otic capsule. There was no association between the presence of IAC diverticula and age (P = .13). In six patients with unilateral diverticula, pure tone average (P = .42), and word recognition (P = .27) scores were not significantly different when compared to the normal, contralateral side. CONCLUSIONS: The prevalence of IAC diverticula in children is lower than the prevalence in adults. IAC diverticula in children likely represent congenital variants of temporal bone anatomy. Similar to adult populations, there is evidence that IAC diverticula in children are likely not an independent risk factor for hearing loss. LEVEL OF EVIDENCE: 4 Laryngoscope, 131:E1683-E1687, 2021.

Temporal bone resection for lateral skull-base malignancies.

INTRODUCTION: Malignancies involving the temporal bone are increasingly common and require specialized multi-disciplinary care. Given this complex location, involvement of the lateral skull base and local neurovascular structures is common. In this review we discuss general principles for temporal bone resection, as well as alternative and complementary surgical approaches that should be considered in the management of patients with temporal bone cancer. METHODS: A comprehensive review on literature pertaining to temporal bone resection was performed. RESULTS: The primary surgical strategy for malignancies of the temporal bone is temporal bone resection. This may be limited to the ear canal and tympanic membrane (lateral temporal bone resection) or may include the otic capsule and its contents (subtotal temporal bone resection), and/or the petrous apex (total temporal bone resection). Management of adjacent neurovascular structures including the facial nerve, the carotid artery, and the jugular bulb/sigmoid sinus should be considered during surgical planning. Finally, adjunctive procedures such as parotidectomy and neck dissection may be required based on tumor stage. CONCLUSIONS: Temporal bone resection is an important technique in the treatment of lateral skull-base malignancies. This strategy should be incorporated into a multi-disciplinary approach to cancer.

The Size of Internal Auditory Canal Diverticula Is Unrelated to Degree of Hearing Loss.

OBJECTIVES: To explore the relationship between hearing loss and the internal auditory canal (IAC) diverticula. To determine whether diverticula exist within or medial to the otic capsule and the prevalence in a control population. METHODS: Retrospective review of adult patients with radiologic evidence of an IAC diverticulum, no evidence of otosclerosis, and audiometric testing. Analyzed degree of hearing loss and width, length, height, and volume of diverticulum. Hounsfield unit (HU) measurements lateral and medial to the diverticulum. RESULTS: Pure tone average (PTA), air-bone gap, and WRS (word recognition score) did not correlate with length, width, height, and volume of the diverticula. In patients with a unilateral diverticulum, there was no difference in mean PTA or WRS when comparing the diverticulum and nondiverticulum sides. Mean HU lateral to the diverticulum (2104 HU) was found to be significantly higher than medial to the diverticulum (1818 HU). There is a 5.6% prevalence of IAC diverticula in patients who underwent high-resolution computed tomography (CT) scans for chronic sinusitis (control group). CONCLUSION: These data support the notion that hearing loss in this population is a product of sampling bias. The size of IAC diverticula does not correlate with the degree of hearing loss, and there is no statistically significant association between sensorineural hearing loss (SNHL) and the presence of an IAC diverticulum. IAC diverticula may exist medial to, rather than within, the otic capsule given the significant difference in mean HUs medial and lateral to the diverticula. LEVEL OF EVIDENCE: 4 Laryngoscope, 130:1011-1015, 2020.

A novel etiology for pneumolabyrinth after temporal bone fracture without otic capsule involvement.

Pneumolabyrinth has been considered an indicator of otic capsule involvement in temporal bone fractures. We present a novel theory for the etiology of pneumolabyrinth in a trauma patient without an otic capsule fracture: passage of intrathecal air into the labyrinth. Our patient experienced transient bilateral pneumolabyrinth after head trauma due to a motor vehicle collision. The patient was noted to have extensive pneumocephalus and a unilateral temporal bone fracture that spared the otic capsule. Initial computed tomography (CT) scans demonstrated air in the cochlea and both internal auditory canals. A high-resolution CT scan 6 hours later showed resolution of this air. Pneumolabyrinth may not be a sensitive indicator of otic capsule involvement in temporal bone fractures. In addition to middle ear sources, air in the labyrinth can also plausibly originate intrathecally, especially in the setting of pneumocephalus.

A large vestibular schwannoma after recent negative MRI: A case report.

Vestibular schwannomas are, on average, slowly growing tumors that may remain quiescent for some time before manifesting themselves symptomatically or being found incidentally on imaging. We describe a case of a vestibular schwannoma that grew rapidly and to a large size in a patient who had undergone negative imaging 5 years earlier for unrelated issues. This case highlights the importance of repeat imaging in patients with symptoms concerning for vestibular schwannoma who might have previously undergone negative scans.