Leptomeningeal metastases: 111indium-DTPA CSF flow studies.

Thirty consecutive patients with cytologically documented leptomeningeal metastases (LM) underwent intraventricular 111indium-DTPA (In) CSF flow studies (FS). Sixteen patients (53%) had normal In FS. Fourteen patients (47%) had documented compartmentalization of the CSF system. In four patients unsuspected CSF block was confined to the base of brain with limited spinal descent and poor cerebral convexity ascent of In. All patients received whole-brain irradiation and two were subsequently shown to have normal In FS. In 10 other patients, suspected (eight) and unsuspected (two) spinal blocks were seen. Patients with spinal blocks underwent CT myelography or spine MR and were subsequently treated with involved-field irradiation. Following radiation therapy, normal In FS were achieved in only two patients with documented spinal cord blocks. In conclusion, antegrade In FS in patients with LM are useful in defining levels of CSF blocks. Following treatment of patients with CSF blocks with involved-field irradiation, normal In FS can be restored in approximately one third.