At Memorial Sloan-Kettering Cancer Center (MSKCC), approximately 10% of patients referred for placement of Ommaya reservoirs have or develop hydrocephalus.6 This is typically communicating hydrocephalus, resulting from occlusion of the arachnoid granulations necessary for CSF resorption into the venous system or from basilar carcinomatous meningitis. On rare occasions patients will develop a non-communicating hydrocephalus secondary to an obstructing lesion at the foramen of Monro, Sylvian aqueduct, or fourth ventricle. When obstruction occurs of either communicating or non-communicating variants, the ventricles will normally dilate making the diagnosis evident. However, a small percentage of patients will have non-compliant, small or "slit" ventricles which result in markedly elevated intracranial pressure without radiographically-apparent hydrocephalus. Patients with elevated intracranial pressure often present with severe headaches, emesis, and altered levels of consciousness in addition to focal neurologic deficits.
Acute hydrocephalus in patients with leptomeningeal disease is an urgent situation requiring a ventriculoperitoneal shunt (Fig. 5).
Study Date:3/4/04 Study Time:7:32:59 PM MRN:
Figure 5. Hydrocephalus and Leptomeningeal Disease: Non-contrast CT showing ventricular dilation in a patient undergoing Ommaya reservoir placement for leptomeningeal disease.
Patients who develop hydrocephalus and already have had an Ommaya reservoir placed have the advantage of being able to have a neurosurgeon connect a shunt valve and peritoneal catheter sequentially to their reservoir, thereby avoiding a second intracranial surgery. Conversely, for patients with hydrocephalus who later require IT chemotherapy for treatment of leptomeningeal disease, the option of turning up a programmable valve on a ventriculoperitoneal shunt to allow CSF drug delivery and then turning the valve back to the original setting to permit CSF drainage is invaluable. On-off valves were used for many to years to achieve this purpose, but they were relatively cumbersome to use and unreliable. Over the past five years at MSKCC, we have utilized the Codman-Hakim programmable valve (Johnson and Johnson, Raynham, MA), which uses a magnet to control the resistance in the valve (Fig. 6).
Figure 6. Conversion of an Ommaya Reservoir to Ventriculoperitoneal Shunt: Placement of Ommaya catheter with convertible reservoir (A), allows easy conversion to a Ventriculoperitoneal shunt (B), while still allowing intermittent chemotherapy infusions. Figure 6b image courtesy of Integra Life Sciences Corporation
During drug delivery, the valve is placed to the highest setting and then reset after four hours. A plain radiograph of the skull will show that the valve has been reset. The valve can be reset repeatedly without damaging the mechanism. One patient has been treated for leptomeningeal disease from
metastatic breast carcinoma every other week for two years without encountering any difficulties with the valve.
Of practical note for oncologists and neurologists, it should be emphasized that when instilling chemotherapy, it is necessary to withdraw CSF equal to the amount to be instilled. Difficulty in obtaining CSF can be secondary to slit or small ventricles. This difficulty can be remedied by placing the patient in Trendelenburg position and waiting for CSF to accumulate. It is also worth mentioning endoscopic third ventriculostomies. Their recent increase in popularity has made it more likely that well-informed patients will inquire about the possibility of having the procedure done in lieu of one requiring permanent hardware. While third ventriculostomy has gained acceptance for the treatment of many types of hydrocephalus, it is not an option in patients with leptomeningeal tumor both because it is ineffective in treating communicating hydrocephalus and does not address the need for a chemotherapy delivery system.
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