Preoperative diagnosis of intramedullary spinal schwannomas.

Intramedullary spinal schwannomas are rare benign spinal cord tumors and are easily misdiagnosed because of the imaging characteristics shared with intramedullary glioma. Correct preoperative definitive diagnosis is essential for treatment and prognosis. To improve the preoperative diagnostic strategy, clinical and imaging data of seven patients with intramedullary spinal schwannoma (6 men, mean age 44 years, mean duration of illness 4.2 years) treated in our department between 2003 and 2010 were collected and retrospectively evaluated. The cervical cord was affected in five patients, followed by the thoracic cord in two. All seven cases were misdiagnosed as intramedullary glioma based on the imaging characteristics. Comparison of the clinical features of these 7 patients with those of patients with intramedullary tumors (173 ependymomas and 70 astrocytomas) admitted during the same period revealed significant differences in somatic pain and root pain as the initial symptoms between intramedullary spinal schwannomas and ependymomas (p = 0.005) and between intramedullary spinal schwannomas and astrocytomas (p = 0.019), but not between ependymomas and astrocytomas (p = 0.175). Root or somatic pain as an initial symptom is important for the preoperative diagnosis of intramedullary spinal schwannoma, especially if the imaging characteristics are not entirely specific.