Findings
Pre- and postcontrast MR was performed of the brain and internal auditory canal.
Brain: Sagittal T1-weighted images demonstrate corpus callosum to be intact. No evidence of Chiari malformation. No abnormal pineal region masses. Pituitary gland is not enlarged. Diffusion imaging demonstrates no evidence of recent infarct. Axial FLAIR and T2-weighted images demonstrate mild prominence of the sulci and ventricles. Multiple punctate areas of increased FLAIR and T2 signal are seen in the juxtacortical, centrum semiovale, and periventricular white matter. These findings are likely due to microvascular angiopathy. No evidence of vasogenic edema or mass effect. Contrast-enhanced T1-weighted images show no abnormal intraaxial enhancing masses.
Internal Auditory Canals: Pre- and postcontrast images were performed through the internal auditory canals. Study demonstrates a likely low left-sided vestibular schwannoma that extends from the left cerebellopontine angle into the porous acusticus and involves the proximal two-thirds of the left internal auditory canal. The lesion does not extend into the fundus of the internal auditory canal. The lesion is isointense to brain on T1 and avidly enhances with contrast with heterogeneous T2 signal suggesting the diagnosis of vestibular schwannoma. There is mass effect on the underlying left middle cerebellar peduncle with mild effacement of the 4th ventricle. The posterior fossa component of the lesion measures approximately 1.8cm x 1.5cm in the transverse plane and approximately 2cm in the craniocaudad plane. The lesion extends into and widens the adjacent porous acusticus.
Thin-section T2 DRIVE sequences demonstrate mass effect with compression of the individual nerves of the left 7th and 8th nerve complex within the internal auditory canal. The contrast-enhanced T1-weighted images suggest some possible subtle enhancement of the nerves. There is no evidence of extension into the cochlear canal to involve the modiolus. Bilateral cochlea appear to have 2-1/2 turns. Basilar membrane is visualized. Modiolus is intact. No obvious evidence of congenital inner-ear malformation is identified. No evidence of enlarged vestibular aqueduct.
Conclusions
Left vestibular schwannoma with both posterior fossa and internal auditory canal components as described above.