Assessment of the cochlear nerve to facial nerve size ratio using MR multiplanar reconstruction of the internal auditory canal in patients presenting with acquired long-standing hearing loss.

OBJECTIVE: To test using the facial nerve as a reference for assessment of the cochlear nerve size in patients with acquired long-standing sensorineural hearing loss (SNHL) using MRI multiplanar reconstruction. METHODS: The study was retrospectively performed on 86 patients. Group 1 (study group, n = 53) with bilateral long-standing SNHL. Group 2 (control group, n = 33) without hearing loss. The nerve size was measured by drawing a region of interest around the cross-sectional circumference of the nerve in multiplanar reconstruction images. RESULTS: No significant correlation was noted between the cochlear nerve and facial nerve size, and the patient's age, gender and weight (p > 0.05). In Group 1, the mean ratio of the cochlear to facial nerve size was 0.99 ± 0.30 (range: 0.52-1.86) and 1.12 ± 0.35 (range: 0.34-2.3) for the right and left sides, respectively. In Group 2, it was 1.18 ± 0.23 (range: 0.78-1.71) and 1.25 ± 0.25 (range: 0.85-1.94) for the right and left sides, respectively. The cochlear nerve size was statistically (p = 0.0004) smaller in Group 1 than in Group 2. CONCLUSION: The cochlear nerve size and the cochlear to facial nerve size ratio are significantly smaller in patients with acquired long-standing SNHL. Advances in knowledge: The facial nerve can be used as a reference for assessment of the cochlear nerve in patients with acquired long-standing SNHL.

Assessment of surgically assisted rapid maxillary expansion regarding pterygomaxillary disjunction using thin volume-rendering technique: in variance analysis and in reliability, accuracy, and validity.

PURPOSE: To assess surgically assisted rapid maxillary expansion (SARME) with or without pterygomaxillary disjunction using a thin volume-rendering technique in variance analysis and in reliability, accuracy, and validity. MATERIALS AND METHODS: Thin volume-rendered images of 68 patients were evaluated preoperatively and 2.87 ± 1.59 months after expansion with respect to dentoskeletal effects. RESULTS: Variance analysis of SARME with pterygomaxillary disjunction showed an important decrease in transverse widening and segmental outward inclination and an increase in vestibular bone plate thickness (premolars) in patients younger than 20 years with bone-borne devices; the greatest increase in transverse widening was in patients with 3-segment osteotomy and tooth-borne devices. Analysis of SARME without pterygomaxillary disjunction showed an important decrease in transverse widening and segmental inward inclination in patients older than 20 years with bone-borne devices; the greatest pterygoid lateral bending was in patients with 2-segment osteotomy and bone-borne devices. CONCLUSION: The performance of pterygomaxillary disjunction should depend on patient age (ie, treatment with pterygomaxillary disjunction in those >20 years old; treatment without pterygomaxillary disjunction in those <20 years old). Patients with pterygomaxillary disjunction, 3-segment osteotomy, and tooth-borne devices tended to show an increase in transverse widening but at the price of greater attachment loss. Patients younger than 20 years with pterygomaxillary disjunction and bone-borne devices tended to show an increase in vestibular bone plate (premolars) but at the price of decrease in transverse widening.