Abstract
BACKGROUND: Intra-cerebrospinal fluid (CSF) chemotherapy delivered through an Ommaya reservoir is a treatment for certain patients with leptomeningeal metastasis (LM). Numerous administration strategies are advocated in the literature and are used in practice. We evaluated differences in drug delivery associated with the three most used techniques. METHODS: Consecutive patients with newly diagnosed LM underwent conventional CSF flow studies using indium-111-DTPA (n = 104). Three different administration techniques and two different radionuclide volumes were used. Techniques evaluated were administration of the radionuclide followed by repeated compression of the Ommaya bulb, administration mixed with an equal volume of CSF followed by compression, and barbotage with CSF withdrawn prior to chemotherapy injection. Residual radionuclide counts were measured in the injection syringe, butterfly needle/stopcock apparatus, and reservoir bulb after radionuclide administration. In addition, U.S. neuro-oncologists were surveyed regarding their intra-CSF chemotherapy administration techniques. RESULTS: For the 3 mL injection volume, 53.5%, 28.0%, and 3.14% of the radionuclide never reached the patient using the bulb compression, CSF-drug mixing followed by compression, and barbotage techniques respectively (P < .00001). For the 5 mL injection volume, the corresponding percentages were 23.3%, 18.7%, and 3.0% (P < .0001). The survey of U.S. neuro-oncologists revealed that a majority (56%) do not use a barbotage procedure for chemotherapy administration. CONCLUSIONS: A large proportion of radionuclide injected into Ommaya reservoirs never reaches the patient unless a barbotage technique is used. This finding likely applies to intraventricular chemotherapy injections as well and may represent one easily remediable reason for the poor efficacy of intraventricular chemotherapy in patients with LM.