aneurysm clips (metal clips on the wall of a large artery) , or shrapnel 
fragments . 
I 
Risk of Surgery: 
The surgical risks depend on the preoperative condition of the 
patient, the nature of the operation, and the location and size of the 
tumor. Known risk associated with brain surgery include: hemorrhage, 
deterioration of neurological functions (such as weakness in the arm 
and/or leg, loss of sensation over parts of the body, and partial or 
complete loss of functions related to communication such as speech and 
comprehension, and other functions related to intellectual capacity, 
memory, etc.), infection and death. The relative risk will be discussed 
with you in accordance with your child's condition, specific findings 
and planned surgical procedures. 
Risk of the Ommaya reservoir: 
The Ommaya reservoir is a commonly used device in neurosurgery. 
The Ommaya reservoir is inserted under the skin with an attached tube 
that extends into the area of tumor. To use the Ommaya reservoir, the 
overlying skin is cleansed and needle is inserted through the skin into 
the chamber. The potential complications relating to the use of the 
Ommaya reservoir are infection and bleeding. Every effort will be made 
to maintain sterility and prevent bleeding. 
Risk of the Vector /TK Gene Transfer: 
Even though the vector-producing cells cannot grow and are 
considered harmless in humans, it is possible that events could occur 
within the cells that would permit the vector to grow and/or make the 
cells cancerous. Gene transfer using similar vectors has been used in 
adult and child patients. Since these experiments started in 1989, none 
of the more than 20 people who have received cells into which genes had 
been transferred by vectors has developed any problems related to the 
gene transfer method. We believe these vectors are safe and are not a 
threat to other people or to society. 
This method of treatment has 2 major potential problems. First, 
the vector may be passed into surrounding normal tissue in addition to j 
tumor tissue. We have not found any evidence of problems in mice and 
rats due to the spread of vector to surrounding normal brain tissue or 
to other sites in the body. We believe that some of the surrounding 
blood vessel cells probably do have the vector, but the number is too 
small to result in significant adverse side effects. It is possible 
that bleeding and “-neurologic symptoms (headache, convulsions, stroke) 
may develop with Cytovene. 
I 
Second, the vector-producing cells might persist in your child's 
body and cause cancer or other disease. We expect the immune system to 
reject (kill) the vector-producing cells in 1-2 weeks. Thus, they 
should not be able to survive and grow in your child's body. In 
addition, we expect the Cytovene therapy will kill all cells with the 
vector, including the vector-producing cells. Therefore, the vector- 
producing cells should not survive and the insertion of the vector 
should not result in new cancerous cells, since we think all of the 
cells with the vector will be killed by Cytovene. Therefore, we feel 
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