Anand V. Kasbekar

Non echo planar, diffusion-weighted magnetic resonance imaging (periodically rotated overlapping parallel lines with enhanced reconstruction sequence) compared with echo planar imaging for the detection of middle-ear cholesteatoma

OBJECTIVES We evaluated use of the periodically rotated overlapping parallel lines with enhanced reconstruction diffusion-weighted imaging sequence, compared with conventional echo planar magnetic resonance imaging, in the detection of middle-ear cholesteatoma. MATERIAL AND METHODS Sixteen patients awaiting second-stage combined approach tympanoplasty and three patients awaiting first-stage combined approach tympanoplasty underwent magnetic resonance imaging with both (1) the periodically rotated overlapping parallel lines with enhanced reconstruction sequence (i.e. non echo planar imaging) and (2) the array spatial sensitivity encoding technique sequence (i.e. echo planar imaging). Two neuroradiologists independently evaluated the images produced by both sequences. Radiology findings were correlated with surgical findings. RESULTS AND ANALYSIS Seven cholesteatomas were found at surgery. Neither of the assessed imaging sequences were able to detect cholesteatoma of less than 4 mm. Rates for sensitivity, specificity, and positive and negative predictive values are presented. CONCLUSION Decisions on whether or not to operate for cholesteatoma cannot be made based on the two imaging sequences assessed, as evaluated in this study. Other contributing factors are discussed, such as the radiological learning curve and technical limitations of the magnetic resonance imaging equipment.

Developmental changes in cochlear orientation--implications for cochlear implantation.

Objectives: To investigate changes in cochlear orientation with age and discuss the implications of any change with respect to cochlear implantation. Study Design: Cross-sectional study of computed tomographic scans of the temporal bones in patients with no congenital abnormalities. Patients: One hundred fifty-nine patients were included in the study, making a total of 318 ears. The age range was 9 months to 85 years. Intervention: Axial computed tomographic scans showing the basal turn of the cochlea were identified. The angle of the basal turn of the cochlea was measured by drawing a line through the long axis of the basal turn and measuring its angle with a line drawn through the midsagittal plane. The patients were grouped according to age, and a 1-way analysis of variance was used to identify any statistically significant change in basal turn angulation. Interobserver and intraobserver errors were calculated and presented as repeatability coefficients. The basal turn angles of 3 difficult cases of cochlear implantation were related to the findings. Results: The mean basal turn angle was 54.6 degrees (range, 46.8-63.8 degrees; standard deviation, 3.5). There was a statistically significant reduction in the angulation of the basal turn with increasing age (F = 10.1; p = 0.002). The majority of the change occurs between the ages of 11 and 15 years. The interobserver reliability coefficient was 4.8. The intraobserver reliability coefficient was 2.0. The 3 difficult cases had basal turn angles that were at the upper limit of the reference range. Conclusion: There is a statistically significant reduction in basal turn angulation relative to the midsagittal plane with increasing age. However, care should be taken in interpreting these results in light of the inherent error in the measuring technique, although the intraobserver repeatability coefficient was only 2.0. The more obtuse angulation of the basal turn in children may have implications for cochlear implantation.

Growth characteristics of vestibular schwannomas.

Objective To assess the growth characteristics of small- to medium-sized vestibular schwannomas in patients undergoing watch, wait, and rescan management. Study Design Cohort study using prospectively collected size and tumor morphology data. Setting Tertiary referral center for cranial base surgery. Subjects and Methods Three hundred eighty-one patients with sporadic unilateral vestibular schwannomas and 2 or more magnetic resonance scans were included. Linear measurements were used to assess tumor size. The point of growth and pattern of growth progression were assessed. Factors influencing growth were investigated. Results Approximately 33% of tumors demonstrated significant growth. Mean size at presentation was 9.9 mm (standard deviation [SD]. 4.8). For growing tumors, mean size at final review was 13.7 mm (SD, 4.8). This was a statistically significant increase in size (p < 0.0001). Mean annual change in size for growing tumors was 2.3 mm (SD, 2.3). 52.4% of growing tumors showed radiologically demonstrable first growth within 18 months of presentation. Approximately 7.2% of tumors showed radiologically demonstrable first growth after 5 years of follow-up. There were no demographic or morphologic predictors of growth. Conclusion Tumor growth is usually slow and is most likely to occur within the first 3 years of observation. Growth may occur after five years of follow-up. A protocol for the scanning of patients is suggested based on the findings of the study.

Facial nerve palsy secondary to middle-ear lipoma.

OBJECTIVE We present the first reported case of a middle-ear lipoma presenting with facial nerve palsy. We review the available literature on middle-ear lipomas and alert the surgeon to the possibility of a lipoma occurring in this location. CASE REPORT A 33-year-old man presented to our unit with a right-sided, House-Brackmann grade two, lower motor neurone facial palsy. A computed tomography scan revealed abnormal soft tissue in the epitympanic recess, extending to the region of the geniculate ganglion. At middle-ear exploration, a lump of fatty tissue was found filling the anterior middle-ear cleft, juxtaposed to the horizontal portion of the facial nerve. The patients facial palsy resolved within a few weeks of surgery. CONCLUSION Lipomas are a rare but real differential diagnosis of a mass in the middle ear. Early imaging is advised.

Cochlear Rotation and its Relevance to Cochlear Implantation

Abstract Objectives: To investigate changes in cochlear orientation with age and discuss the implications of any change with respect to cochlear implantation. Study Design: Cross-sectional study of computerized tomography scans of the temporal bones in patients with no congenital abnormalities. Patients: 159 patients were included in the study making a total of 318 ears. The age range was nine months to eighty five years. Intervention: Axial compututed tomography scans showing the basal turn of the cochlea were identified. The angle of the basal turn of the cochlea was measured by drawing a line through the long axis of the basal turn and measuring its angle with a line drawn through the midsagittal plane. The patients were grouped according to age and a one way analysis of variance was used to identify any statistically significant change in basal turn angulation. Inter- and intra-observer errors were calculated and presented as repeatability co-efficients. The basal turn angles of 3 difficult cases of cochlear implantation were related to the findings. Results: The mean basal turn angle was 54.6° (range 46.8–63.8°; SD 3.5°). There was a statistically significant reduction in the angulation of the basal turn with increasing age (F = 10.1; p = 0.002). The majority of the change occurs between the ages of eleven and fifteen. The inter-observer reliability co-efficient was 4.8. The intra-observer reliability co-efficient was 2.0. The 3 difficult cases all had basal turn angles that were at the upper limit of the normal range. Conclusions: There is a statistically significant reduction in basal turn angulation relative to the midsagittal plane with increasing age. However, care should be taken in interpreting these results in light of the inherent error in the measuring technique although the intra-observer repeatability coefficient was only 2.0. The more obtuse angulation of the basal turn in children may have implications for cochlear implantation.

An Audit of Pre-operative CT Scans in Adult Cochlear Implantation

Abstract Introduction: Currently pre-operative CT scanning of the temporal bones forms part of the routine adult cochlear implantation assessment. The case for post-operative CT scans is emerging. In order to establish the influence CT scans had on implantation decisions, a retrospective analysis of the pre-operative CT findings in adult CI patients was undertaken. Methods: 175 consecutive pre-operative CT scans were reviewed. Results: 25 of 175 scans (14%) showed an abnormality. Only 3 of 175 (1.7%) scans demonstrated abnormalities that influenced the side of implant or decision to implant. Conclusion: More focused use of pre-operative CT scanning may reduce unnecessary scans and allow further utilization of post-operative CT imaging.