Evolution of computed tomographic abnormalities in leptomeningeal metastases.

We obtained serial cranial computed tomographic (CT) scans from 25 patients with documented leptomeningeal metastases in order to correlate the course of clinical symptoms and cerebrospinal fluid abnormalities with the evolution of CT abnormalities. In almost one-third of patients, relatively specific CT findings such as enhancement of the meninges, obliteration of cisterns or sulci, and hydrocephalus with transependymal edema preceded clinical symptoms. By the time patients became symptomatic, 10 of 25 (40%) had specific abnormalities, and 4 more became specifically abnormal with time. The first scan after cerebrospinal fluid tumor cells were discovered showed specific abnormalities in only 6 patients, but 7 more became specifically abnormal with time. Ventriculomegaly occurred in 18 of 25 patients (72%) and was associated with sulcal and/or cisternal obliteration in one-half of the patients. In 4 patients sulcal and cisternal obliteration developed prior to ventricular enlargement. Multiple small, enhancing cortical nodules were detected prior to symptom onset and discovery of leptomeningeal tumor in 5 patients.