John I. Lane

The Utility of Diffusion-Weighted Imaging for Cholesteatoma Evaluation

SUMMARY: DWI is a useful technique for the evaluation of cholesteatomas. It can be used to detect them when the physical examination is difficult and CT findings are equivocal, and it is especially useful in the evaluation of recurrent cholesteatoma. Initial DWI techniques only detected larger cholesteatomas, >5 mm, due to limitations of section thickness and prominent skull base artifacts. Newer techniques allow detection of smaller lesions and may be sufficient to replace second-look surgery in patients with prior cholesteatoma resection.

Scalar Localization of the Electrode Array After Cochlear Implantation: A Cadaveric Validation Study Comparing 64-slice Multidetector Computed Tomography With Microcomputed Tomography

Hypothesis: Improved resolution available with 64-slice multidetector computed tomography (MDCT) could potentially be used clinically to localize the cochlear implant (CI) electrode array within the basal turn. Background: In CI surgery, the electrode array should be inserted into and remain within the scala tympani to avoid injury to Reissners membrane and the scala media. Correlating the position of the electrode in the basal turn with surgical technique and implant design could be helpful in improving outcomes. Methods: After a standard left mastoid exposure of the round window niche through the facial recess performed on a cadaver head, an electrode array from a Nucleus Softip Contour CI was fully inserted through a cochleostomy. The head was then scanned axially on a 64-slice MDCT with 0.4-mm slice thickness and reconstructed into the oblique axial, oblique coronal, and oblique sagittal planes of the cochlea. The temporal bone was then harvested and imaged on a microcomputed tomographic scanner using 20-&mgr;m slice thickness. Identical reconstructions were made and compared with the 64-slice images to confirm exact location of the electrode array. Results: The 64-slice MDCT accurately localized the electrode array to the scala tympani. This was best demonstrated in the oblique sagittal plane, identifying the electrode array in the posterior inferior portion of the basal turn, posterior to the spiral lamina. Conclusion: This ex vivo validation study suggests that 64-slice MDCT has the potential to allow accurate localization of the CI electrode array within the basal turn of the cochlea.

Magnetic resonance imaging surveillance following vestibular schwannoma resection.

To describe the incidence, pattern, and course of postoperative enhancement within the operative bed using serial gadolinium‐enhanced magnetic resonance imaging (MRI) following vestibular schwannoma (VS) resection and to identify clinical and radiologic variables associated with recurrence.

Magnetic Resonance Imaging With Cochlear Implant Magnet in Place: Safety and Imaging Quality.

Objective To evaluate the safety and image quality of 1.5-T MRI in patients with cochlear implants and retained internal magnets. Study Design Retrospective case series from 2012 to 2014. Setting Single tertiary academic referral center. Patients All cochlear implant recipients undergoing 1.5-T MRI without internal magnet removal. Intervention(s) MRI after tight headwrap application. Main Outcome Measures Patient tolerance, complications, and characteristics of imaging artifact. Results Nineteen ears underwent a total of 34 MRI scans. Two patients did not tolerate imaging with the headwrap in place and required magnet removal before rescanning. One subject experienced two separate episodes of polarity reversal in the same device from physical realignment (i.e., flipping) of the internal magnet requiring surgical repositioning. Three patients were discovered to have canting of the internal magnet after imaging. In all three cases, the magnet could be reseated by applying gentle firm pressure to the scalp until the magnet “popped” back into place. These patients continue to use their device without difficulty and have not required surgical replacement. In patients receiving head MRI, the ipsilateral internal auditory canal and cerebellopontine angle could be visualized without difficulty in 94% of cases. There were no episodes of cochlear implant device failure or soft tissue complications. Conclusion Under controlled conditions, 1.5-T MRI can be successfully performed in most patients without the need for cochlear implant magnet removal. In nearly all cases, imaging artifact does not impede evaluation of the ipsilateral skull base. Patients should be counseled regarding the risk of internal magnet movement that may occur in up to 15% of cases, even with tight headwrap application. If internal magnet polarity reversal occurs, a trial of reversing the external magnet can be considered. If canting or mild displacement of the internal magnet occurs, an attempt at reseating can be made by applying gentle firm pressure to the scalp over the internal magnet. If conservative measures fail, the magnet should be surgically repositioned to minimize interruption of device use and to prevent scalp complications.

Primary inner ear schwannomas: a case series and systematic review of the literature.

To describe the natural history of primary inner ear schwannomas (PIES) and evaluate management outcomes and relationship between PIES location, clinical presentation, and time to diagnosis.

Scalar localization of the electrode array after cochlear implantation: clinical experience using 64-slice multidetector computed tomography.

Objective: To use the improved resolution available with 64-slice multidetector computed tomography (MDCT) in vivo to localize the cochlear implant electrode array within the basal turn. Study Design: Sixty-four-slice MDCT examinations of the temporal bones were retrospectively reviewed in 17 patients. Twenty-three implants were evaluated. Setting: Tertiary referral facility. Patients: All patients with previous cochlear implantation evaluated at our center between January 2004 and March 2006 were offered a computed tomographic examination as part of the study. In addition, preoperative computed tomographic examinations in patients being evaluated for a second bilateral device were included. Intervention: Sixty-four-slice MDCT examination of the temporal bones. Main Outcome Measure: Localization of the electrode array within the basal turn from multiplanar reconstructions of the cochlea. Results: Twenty-three implants were imaged in 17 patients. We were able to localize the electrode array within the scala tympani within the basal turn in 10 implants. In 3 implants, the electrode array was localized to the scala vestibuli. Migration of the electrode array from scala tympani to scala vestibuli was observed in three implants. Of the 7 implants in which localization of the electrode array was indeterminate, all had disease entities that obscured the definition of the normal cochlear anatomy. Conclusions: Sixty-four-slice MDCT with multiplanar reconstructions of the postoperative cochlea after cochlear implantation allows for accurate localization of the electrode array within the basal turn where normal cochlear anatomy is not obscured by the underlying disease process. Correlating the position of the electrode in the basal turn with surgical technique and implant design could be helpful in improving outcomes.

SUPERFICIAL SIDEROSIS: SEALING THE DEFECT

Superficial siderosis (SS) of the CNS results from chronic hemorrhage into the subarachnoid space with hemosiderin deposition in the subpial layers.1,2 The clinical presentation includes progressive ataxia and deafness. Some patients have a history of trauma or intradural surgery. Despite extensive investigations, a cause of bleeding is frequently elusive. An extra-arachnoid, intraspinal, or intracranial CSF collection, often longitudinally extensive, is sometimes identified in spinal neuroimaging in SS.1–6 A dynamic CT myelogram can identify the dural defect connecting the intrathecal space with the fluid-filled collection.4 The precise mechanism of bleeding is unknown. Rarely CSF hypovolemia accompanies SS.6 Increased CSF RBC count may be seen in CSF hypovolemia.7 These observations have led to the suggestion that repairing the dural defect may halt bleeding and prevent deficit progression.6 Clinical confirmation of this hypothesis is lacking. We describe a patient with SS and CSF hypovolemia due to a CSF leak. Repair of the leak was accompanied by clinical improvement and resolution of neuroimaging and CSF abnormalities. ### Case report. A 64-year-old man was evaluated for a 3-year history of progressive imbalance and 10-year history of decreased hearing. His history was remarkable for childhood poliomyelitis. Over the years he had multiple horse riding-related falls. Twenty years earlier he had a C4-C7 laminectomy for right upper limb weakness. On examination, he had mild …

Arrested Pneumatization of the Skull Base: Imaging Characteristics

OBJECTIVE Arrested skull base pneumatization is a benign developmental variant that can be confused with significant skull base disease processes. This study reviews the imaging findings in 30 suspected cases of arrested skull base pneumatization. CONCLUSION When encountering a nonexpansile lesion with osteosclerotic borders, internal fat, and curvilinear calcifications in the basisphenoid bone or adjacent skull base, radiologists should strongly consider the diagnosis of arrested pneumatization.

Cranial base manifestations of neurosarcoidosis: a review of 305 patients.

Objective Neurosarcoidosis is a rare granulomatous disease that can result in cranial neuropathy, chronic meningitis, and intracranial granuloma formation. Meningeal involvement may cause focal nodular enhancement that can simulate common cranial base tumors. The objective of the current study is to further define the clinical features of neurosarcoidosis in a large cohort of patients, focusing on characteristics relevant to the skull base surgeon. Study Design Retrospective series. Setting Two tertiary academic referral centers. Patients Consecutive patients diagnosed with neurosarcoidosis. Intervention(s) Review of clinical presentation, physical examination, radiologic findings, biopsy results, and laboratory testing. Main Outcome Measures Prevalence and distribution of cranial neuropathy, radiologic features of meningeal enhancement, and patterns of simulated tumors. Results A total of 305 patients met study criteria. The mean age at diagnosis was 47 years and 53% were female. The optic nerve was the most commonly involved cranial nerve, followed by the trigeminal and the facial nerve. Meningeal enhancement was present in 67% of cases with 17% demonstrating focal or multicentric nodular enhancement simulating tumor. The most common locations of inflammatory tumor development included the cavernous sinus, petrous temporal bone, and sphenoid wing; six patients had bilateral internal auditory canal lesions, several mimicking neurofibromatosis type II. Conclusion Establishing the diagnosis of neurosarcoidosis remains challenging. Meningeal involvement and cranial neuropathy often mimic other more common conditions. Careful review of patient history and clinical imaging can reveal important clues toward the diagnosis of neurosarcoidosis. The clinician must maintain a high index of suspicion in patients with atypical presentation to avoid misdiagnosis and facilitate early medical treatment.

Three-dimensional volumetric computed tomographic scoring as an objective outcome measure for chronic rhinosinusitis: clinical correlations and comparison to Lund-Mackay scoring.

We aimed to test the hypothesis that three‐dimensional (3D) volume‐based scoring of computed tomography (CT) images of the paranasal sinuses was superior to Lund‐Mackay CT scoring of disease severity in chronic rhinosinusitis (CRS). We determined correlation between changes in CT scores (using each scoring system) with changes in other measures of disease severity (symptoms, endoscopic scoring, and quality of life) in patients with CRS treated with triamcinolone.