Needle aspiration of intramedullary and intradural extramedullary masses of the spinal canal.

Ten intramedullary and two intradural extramedullary masses of the spinal canal were evaluated with 16 separate needle aspirations. Cord fluctuance at air myelography and/or low density within the cord on computed tomography determined the level of aspiration. The condition of two patients with cystic neoplasms and one with syringohydromyelia improved after fluid removal. Endomyelography demonstrated the extent of eight intramedullary cavities. In syringohydromyelia, this information was used in determining the surgical approach. Aspiration and tissue biopsy enabled successful diagnosis of two cases of intradural extramedullary masses of unknown etiology. Needle aspiration yields valuable diagnostic information and is safe when proper guidelines are followed.