To compare the presentation and outcomes of patients with and without obstructive eustachian tube dysfunction (oETD) undergoing repair of lateral skull base spontaneous cerebrospinal fluid (sCSF) leaks.

Retrospective chart review.

Tertiary referral center.

Adults with lateral skull base sCSF leaks who underwent repairs from January 1, 2011, to December 31, 2020, were collected.

Comparative statistics and effect sizes were used to compare clinical features, operative findings, and outcomes between groups.

Of 92 ears from 89 patients included, 51.1% (n = 47) had oETD. There were no differences in demographics between patients with and without oETD. Mean age was 60.7 ± 13.1 versus 58.5 ± 12.8 years ( d = -0.17 [-0.58 to 0.24]), mean body mass index was 33.8 ± 8.5 versus 36.0 ± 8.0 kg/m 2 ( d = 0.27 [-0.14 to 0.68]), and female sex preponderance was 59.6% (n = 28) versus 68.8% (n = 31; Φ = -0.09), respectively. There were no differences in the radiologic number, size, and locations of defects. Patients with oETD had less pneumatized mastoids than those without oETD ( p = 0.001; Φ = 0.43). Mean change from preoperative to postoperative air pure-tone average for those with and without oETD was -1.1 ± 12.6 versus 0.1 ± 17.2 dB ( d = 0.09 [-0.04 to 0.58]), respectively. Six ears (6.5%; three with and three without oETD) underwent revisions for rhinorrhea/otorrhea between 5 and 28 months postoperatively, during which four leaks were found, the two patients without leaks had oETD.

The presentation of sCSF leaks and outcomes of repairs in patients with oETD do not differ from those without oETD. Although postoperative otorrhea might represent an inflammatory or infectious process in patients with oETD, reexploration is warranted if patients do not improve with conservative treatment.

The petrous apex (PA) is involved in a myriad of pathological conditions, some of which are exclusive in children. Diagnosis may be difficult due to vague clinical presentation, and local examination is challenging owing to its inaccessible location. This is further complicated by multiple unfused sutures and ongoing PA pneumatization in children. Cross-sectional imaging is vital for the evaluation of the PA lesions, due to their precarious location and proximity to the major neurovascular structures. Several classification systems have been proposed for these lesions based on their site of origin, solid or cystic appearance, surgical or non-surgical (no touch lesions) management, and benign or malignant nature. In this article, we emphasize the distinctive role of different cross-sectional imaging modalities in the diagnosis of pediatric PA lesions, with special attention to normal variants that should not be mistaken for pathology. We also propose a radiological classification and algorithmic approach to aid in the precise diagnosis and facilitate appropriate management of the various PA lesions in children.

A 73-year-old male with a history of chronic ataxia presented with transient facial droop to the Emergency Department. A CT angiogram and MRI with diffusion weighted imaging (DWI) were negative for stroke. However, incidental note was made of numerous giant arachnoid granulation pits in the posterior fossa predominantly involving the left occipital bone (Figure 1). These arachnoid pits demonstrated multiple foci of herniation of the adjacent cerebellar parenchyma into the pits with gliosis of the herniated parenchyma and focal encephalomalacia of the subjacent cerebellar parenchyma. Review of bone windows on a remote CT brain performed almost 13 years earlier confirmed this to be a longstanding abnormality (Figure 2). The patient's physical exam was suggestive of cerebellar ataxia with left-sided dysmetria on finger to nose testing and a wide-based unsteady gait.

The central skull base is an anatomically complex region of the head and neck which hosts a variety of neoplastic, vascular, infectious, inflammatory, and developmental pathologies. Evaluation of its intricate anatomy requires dedicated and complementary imaging modalities of MRI and CT. This article will provide a brief review of the anatomy of the central skull base, followed by an overview of common pathologies encountered in this region and their characteristic radiological characteristics.

To investigate the prevalence and impact of obstructive sleep apnea (OSA) and obesity in lateral skull base cerebrospinal fluid leak repair (LSBR) of various etiologies.

Retrospective case review at a tertiary skull base center was conducted of consecutive adults undergoing LSBR via transmastoid, middle cranial fossa, or combined approach between 2013-2018. The following data were collected: demographics, comorbidities, radiology and intraoperative findings, and surgical outcomes including complications and need for revision surgery or shunt placement. Patients with incomplete data or leaks following skull base surgery, trauma or chronic ear disease were excluded.

Ninety-four patients (67.4% female, mean age 53.5 ± 12.9 years) underwent repair for spontaneous (sCSFL, 44%) and other etiology (nsCSFL) leaks. nsCSFL served as a comparison group consisting of leaks status-post lateral skull base surgery, temporal bone fractures, and chronic ear disease. Class III obesity (P = .02), OSA (P = .03), and imaging findings of empty sella (OR = 3.32, P = .02), and skull base thinning including contralateral tegmen thinning (31%, OR = 4.3, P = .02), arachnoid granulations (26%, OR = 4.35, P = .02), and superior canal dehiscence (15.8%, OR = 8.57, P = .04) were more common in sCSFL. Four patients (4.2%) required surgical revision for recurrence, and another four (4.2%) resolved with shunting. Evidence of elevated intracranial hypertension was present in nine patients with sCSF leaks and was predictive of need for revision or shunt procedures (P < .01).

Obesity, OSA, and imaging consistent with elevated intracranial pressures were more common among patients with sCSFL. Elevated intracranial pressure predicted outcomes following multilayer repair of spontaneous CSF leaks LEVEL OF EVIDENCE: 4 Laryngoscope, 130:2234-2240, 2020.

Objective  The main purpose of this article is to investigate the prevalence and features of posterior fossa defects (PFD) in spontaneous cerebrospinal fluid leaks (sCSFL). Design  This is a retrospective case series. Setting  Tertiary skull base center. Participants  Consecutive adults undergoing lateral skull base repair of sCSFL between 2003 and 2018. Main Outcome Measures  The following data were collected: demographics, comorbidities, radiology and intraoperative findings, and surgical outcomes including complications and need for revision surgery or shunt placement. Patients with incomplete data or leaks following skull base surgery, trauma, or chronic ear disease were excluded. Results  Seventy-one patients (74% female, mean age 56.39 ± 11.50 years) underwent repair of spontaneous lateral skull base leaks. Eight ears (7 patients, 11.1%) had leaks involving the posterior fossa plate in addition to defects of the tegmen mastoideum (50%), tegmen tympani (25%), or both (25%). Patients with PFDs more often had bilateral tegmen thinning on imaging (75%, odds ratio [OR]: 10.71, 95% confidence interval [CI]: 2.20-54.35, p =  0.005) and symptomatic bilateral leaks (OR: 9.67, 95% CI: 2.22-40.17, p  = 0.01. All PFD patients had arachnoid granulations adjacent to ipsilateral mastoid cell opacification. However, this finding was often subtle and rarely included on the radiology report. There was no significant difference in body mass index, age, presenting complaints, or operative success between the PFD and isolated tegmen defect sCSFL cohorts. Conclusion  The posterior fossa is an uncommon location for sCSFL. Careful review of preoperative imaging is often suggestive and can inform surgical approach. PFD patients are similar to those with isolated tegmen-based defects in presentation, comorbidities, and outcomes.

The radiologic appearance of arachnoid granulations (AGs) in typical locations is well established and they are rarely mistaken for other pathologies. However, when large and seen in atypical locations, such as along the posterior petrous bone, AGs can be a source of diagnostic and therapeutic confusion. We present two cases of giant posterior temporal bone AGs and review their clinical presentation, potential complications, and an imaging-based differential diagnosis.

Two patients with surgically or pathologically proven giant symptomatic AGs in the posterior petrous bone.

Clinical presentation, radiological features, surgical findings, and potential complications of giant AGs.

In two middle-aged women (37 and 55 years), computed tomography (CT) demonstrated solitary large lytic lesions in the posterior right petrous temporal bone. These were similar in appearance to cerebrospinal fluid (CSF) on magnetic resonance imaging (MRI), though they exhibited some minor deviations such as thin internal septations, mild peripheral enhancement, and heterogeneous signal on fluid-attenuated inversion recovery (FLAIR). The MRI appearance effectively distinguished the giant AGs from other lesions that can occur in this area such as endolymphatic sac tumor (ELST). Surgery was successfully performed to prevent complications from a CSF leak.

The posterior temporal bone is an atypical location for AGs and can lead to diagnostic confusion, particularly when they are large. Familiarity with the characteristic imaging appearance of giant AGs in this location can help avoid misinterpretation as a more aggressive pathology and help recognize patients who are at risk for a CSF leak.

Conclusions Spontaneous defects between the mastoid and the posterior cranial fossa are exceedingly rare. Patients with these lesions may have a lower BMI compared to those with middle cranial fossa encephaloceles, but are otherwise demographically similar. This study recommends repair via a transtemporal approach to allow for examination of the entire posterior face of the temporal bone. Objective To describe cases of spontaneous posterior cranial fossa defects. Methods This study reviewed all cases of spontaneous posterior fossa defects presenting to a tertiary referral center over the last decade and described clinical presentation, imaging, operative findings, and outcomes. We also compared these lesions to those previously reported in the literature as well as the more common spontaneous encephaloceles of the middle cranial fossa. Results This study identified five cases with a mean age of 61.4 years, female-to-male ratio of 4:1, and a mean BMI of 31. Three cases presented with spontaneous pneumocephalus, one with CSF otorrhea, and one as an incidental imaging finding. Four defects were found medial to the sigmoid sinus and one was in the lateral retrosigmoid air cells.

(1) To describe a validated algorithm for measuring tegmen thickness on computed tomography scans. (2) To compare the tegmen thickness in 3 groups: patients with spontaneous cerebrospinal fluid (CSF) leaks, obese controls, and nonobese controls.

Retrospective review.

Patients with spontaneous CSF otorrhea often have highly attenuated tegmen plates. This is associated with obesity and/or idiopathic intracranial hypertension (IIH). No evidence exists, however, that objectively links obesity and/or IIH with skull base attenuation.

This was a retrospective review from 2004 to the present. Patients with spontaneous CSF otorrhea and matched obese (body mass index [BMI] >30 kg/m(2)) and nonobese (BMI <30 kg/m(2)) controls were selected. Tegmen thickness was measured radiographically. Interrater validity was assessed.

Ninety-eight patients were measured: 37 in the CSF group (BMI, 36.6 kg/m(2)), 30 in the obese group (BMI, 34.6 kg/m(2)), and 31 in the nonobese group (BMI, 24.2 kg/m(2)). The CSF group had a significantly thinner tegmen compared to both the obese control (P < .01) and nonobese control (P = .0004) groups. Obese controls had a thinner tegmen than nonobese controls (P < .00001). A significant inverse correlation was detected between skull base thickness and BMI. Signs/symptoms of IIH were most commonly found in the CSF group. Good to very good strength of agreement was detected for measures between raters.

This is the first study to (1) quantify lateral skull base thickness and (2) significantly correlate obesity with lateral skull base attenuation. Patients who are obese with spontaneous CSF leaks have greater attenuation of their skull base than matched obese controls. This finding supports theories that an additional process, possibly congenital, has a pathoetiological role in skull base dehiscence.

Imaging of the skull base presents many challenges due to its anatomical complexity, numerous normal variants and lack of familiarity to many radiologists. As the skull base is a region which is not amenable to physical examination and as lesions of the skull base are generally difficult to biopsy and even more difficult to operate on, the radiologist plays a major role in directing patient management via accurate image interpretation. Knowledge of the skull base should not be limited to neuroradiologists and head and neck radiologists, however, as the central skull base is routinely included in the field of view when imaging the brain, cervical spine, or head and neck with computed tomography or magnetic resonance imaging, and hence, its nuances should be familiar to general radiologists as well. We herein review the imaging findings of a subcategory of lesions of the central skull base, the 'do not touch' lesions.

To raise awareness of the possibility of spontaneous temporal bone cerebrospinal fistula in case of clear retrotympanic effusion.

A 63-year-old man with no particular history presented with unilateral spontaneous right retrotympanic clear effusion. CT found defects in the posterior part of the right temporal bone, in contact with arachnoid granulations, with no other visible abnormalities.

Unilateral clear retrotympanic effusion in an adult subject should, apart from serous otitis media, suggest possible cerebrospinal fistula. In the absence of otologic or traumatic history, arachnoid granulation is one possible etiology, inducing spontaneous cerebrospinal fluid leakage when facing the temporal bone. Diagnosis is suggested by bone defects in the tegmen tympani or posterior wall of the temporal bone on CT, with the adjacent mastoid cavities filled with fluid. Pneumococcal vaccination and early surgical repair of the fistula should be performed to avoid neuromeningeal infection.

Spontaneous cerebrospinal fluid (CSF) leak through the posterior fossa (PF) aspect of the petrous bone is exceedingly rare. A case series allows analysis of etiologies and how they may differ from the more common middle fossa (MF) route of leakage. The design was a retrospective case series. The setting was a tertiary care institution. A series of three patients with PF spontaneous CSF leaks was identified. High-resolution imaging (CT and MRI) and intraoperative observations were evaluated. Both in this series and in previously reported cases, patients share the demographics typically found in the MF leak population. In our series, two patterns of PF CSF leak were identified: (1) large unilateral with cerebellar encephalocele and (2) small punctate defects just lateral to the endolymphatic sac. Two presented with simultaneous MF and PF leaks suggesting a shared etiology, at least in some cases, with a role for increased intracranial pressure. In spontaneous CSF leaks, it is important to evaluate the posterior petrous bone along with the tegmen. The concomitant appearance of MF with PF leaks points out the risk that repair via MF craniotomy could fail to identify a leakage site in the vicinity of the endolymphatic sac.

Arachnoid granulation is often found incidentally in the dural sinuses and skull. It may also enlarge the dural sinus or inner table of the skull. We report a 46-year-old woman who presented with occipital headaches and arachnoid granulations in both transverse sinuses and torcular herophili. Neurological examination was normal. Fundoscopic examination, visual fields and acuity were normal. The headache resolved with medical treatment. No intervention for these lesions was planned. The patient was followed up with magnetic resonance imaging studies.

When performing in situ harvesting of cranial bone grafts, there is a risk of entering the pericranial-intracranial venous system, either directly or indirectly through the arachnoid foveolae. The aims of this study were to investigate the size and location of arachnoid foveolae and to provide an anatomic road map to prevent penetrating these structures.

Three hundred dry skulls were selected from the Hamann-Todd osteological collection (Cleveland, OH); skulls were collected between 1912 and 1938. Our study skulls were limited to whites or African American adults. Exclusion criteria included children (<18 y), ethnic groups other than African Americans and whites, skulls demonstrating fracture or craniofacial abnormalities, or any skull whose age, ethnicity, and sex could not be confirmed. From the 300 skulls in the collection, 200 met the criteria and were included in our review. The mean age of these 200 individuals was 43.86 years, with a male-to-female proportion of 100:100, and a white-to-African American proportion of 144:56. A 500-W candescent light was used to transilluminate the arachnoid foveola, and digital photographs with scale were obtained. The location and diameters of foveolae for arachnoid granulations relative to the coronal and sagittal suture were measured.

Approximately 90% of major arachnoid foveolae are located within 2.5 cm of the coronal and 1.5 cm of the sagittal suture for the left and right parietal bones. Major arachnoid foveolae are located at closer distances to the superior sagittal suture and the coronal suture in the right and left parietal bone than minor foveolae. The results of this study imply that potential complications can be minimized by avoiding these areas and by harvesting in situ bone grafts from the absolute and relative safe zones described in this study.