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A 38 year old male presented with a one month history of progressive right hemiparesis and minimal expressive aphasia. Based upon MRI data, he was suspected of having a left frontal 3X3X3 cm GBM, one centimeter deep and posterior to the motor strip. His signs and symptoms were thought to be due to local mass effect and edema. He was taken to the operating suite, with the assistance of electrophysiological monitoring, underwent general anesthesia and gross total resection of a frozen section proven GBM. The patient awoke with complete resolution of his dysphasia and paresis. Post operative MRI with and without contrast revealed total resection of tumor. The patient was treated with 6000 cGy of external beam radiation and a trial of nitrosourea based chemotherapy beginning one week after surgery. The patient had a repeat MRI with and without contrast four months after surgery that demonstrated a 0.5X0.5X1 cm lesion at the medial border of the previous surgical site. At six months post surgery the patient developed right arm paresis but with no aphasia. MRI revealed a 2X2X2.5 cm recurrent mass centered deep and posterior to the left motor strip, 0.25 cm from the lateral ventricle with minimal mass effect and edema. His Karnovsky score was 90. A Thallium SPECT scan confirmed a metabolically active tumor relieving any suspicion of radiation necrosis. A consent form was obtained for cryoprobe freezing of malignant primary brain tumor, which had failed standard therapy.
The patient was placed on Decadron 36 mg/day one week prior to planned surgery. The patient was admitted to the hospital the morning of surgery and had a CRW stereotactic ring affixed to his skull and scans obtained. A 3-D representation of the tumor in CT and MRI space and optimal cryogenic probe trajectory on Stereoplan (RSA, Burlington, Mass.) image software was produced. Two sites at the edge of the projected ice ball were selected for the placement of thermocouples. The patient was taken to the operating room and mild sedation administered. Two sites on the scalp were prepped, local anesthesia administered, skin incised and a burr hole fashioned, at the proposed entry point. A biopsy of the suspected lesion was obtained with a 10 mm Sudan needle, was sent for frozen section and was confirmed as GBM. The thermocouples were placed through twist drill holes stereotactically at the edge of the tumor. The second site was anesthetized, and a burr hole fashioned and enlarged over the right midparietal area of the opposite hemisphere to accommodate the GERT 3600 5 MHz ultrasound transducer and visualize the tumor. The cryoprobe was inserted, a 3 mm Accuprobe (Cryomedical, Rockville, Maryland) which can produce a 4.0 cm diameter ice ball. The patient was asked to raise both arms and was presented with a series of flash cards to reply to as freezing began. First the probe was cooled to -100 C for 2 minutes, then -150 C for 2 minutes, then -200 C for 4 additional minutes at which time the thermocouples registered -5 C and the ultrasound indicated that the entire tumor was frozen. The (Continued on page 88)
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