[Imaging-based diagnosis of vestibular schwannoma].

Magnetic resonance imaging (MRI) is the imaging method of choice for patients with vestibular schwannoma, with almost 100 % sensitivity and specificity. The role of computed tomography (CT) is limited to preoperative planning and the postoperative phase. High-resolution sequences and the application of gadolinium-based i.v. contrast medium are crucial for MRI-based diagnosis. Description of the size and location of the tumor, as well as its relationship to adjacent structures and anatomic features, is essential, since these factors, in addition to clinical findings, influence the type of treatment, surgical options, and associated risks. A postoperative linear contrast enhancement is often seen for up to 6 months and sometimes even longer. However, if this is of nodular structure, a recurrent schwannoma is likely. A sufficient statement regarding tumor response is not possible within the first 24 months after stereotactic radiosurgery. An increasing tumor volume after 24 months indicates failure of the treatment. Knowledge of the features of vestibular schwannomas allows all other possible differential diagnoses to be confidently excluded.