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Authors: Michael Crichton
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to make sure they were being placed correctly.
Ellis picked up the first electrode array. From where Ross stood, it looked like a single slender wire. Actually, it was a bundle of twenty wires, with staggered contact points. Each wire was coated with Teflon except for the last millimeter, which was exposed. Each wire was a different length, so that under a magnifying glass, the staggered electrode tips looked like a miniature staircase.
Ellis checked the array under a large glass. He called for more light and turned the array, peering at all contact points. Then he had a scrub nurse plug it into a testing unit and test every contact. This had been done dozens of times before, but Ellis always checked again before insertion. And he always had four arrays sterilized, though he would need only two. Ellis was careful.
At length he was satisfied. “Are we ready to wire?” he asked the team. They nodded. He stepped up to the patient and said, “Let’s go through the dura.”
Up to this point in the operation, they had drilled through the skull, but had left intact the membrane of
dura mater
which covered the brain and enclosed thespinal fluid. Ellis’s assistant used a probe to puncture the dura.
“I have fluid,” he said, and a thin trickle of clear liquid slid down the side of the shaved skull from the hole. A nurse sponged it away.
Ross always found it a source of wonder the way the brain was protected. Other vital body organs were well-protected, of course: the lungs and heart inside the bony cage of the ribs, the liver and spleen under the edge of the ribs, the kidneys packed in fat and secure against thick muscles of the lower back. Good protection, but nothing compared to the central nervous system, which was encased entirely in thick bone. Yet even this was not enough; inside the bone there were sac-like membranes which held cerebrospinal fluid. The fluid was under pressure, so that the brain sat in the middle of a pressurized liquid system that afforded its superb protection.
McPherson had compared it to a fetus in a water-filled womb. “The baby comes out of the womb,” McPherson said, “but the brain never comes out of its own special womb.”
“We will place now,” Ellis said.
Ross moved forward, joining the surgical team gathered around the head. She watched as Ellis slid the tip of the electrode array into the burr hole and then pressed slightly, entering the substance of the brain. The technician punched buttons on the computer console. The display screen read: “ ENTRY POINT LOCALIZED .”
The patient did not move, made no sound. The brain could not feel pain; it lacked pain sensors. It was one of the freaks of evolution that the organ which sensed pain throughout the body could feel nothing itself.
Ross looked away from Ellis toward the X-ray screens. There, in harsh black and white, she saw the crisply outlined white electrode array begin its slow, steady movement into the brain. She looked from the anterior view to the lateral, and then to the computer-generated images.
The computer was interpreting the X-ray images by drawing a simplified brain, with the temporal-lobe target area in red and a flickering blue track showing the line the electrode must traverse from entry point to the target area. So far, Ellis was following the track perfectly.
“Very pretty,” Ross said.
The computer flashed up triple coordinates in rapid succession as the electrodes went deeper.
“Practice makes perfect,” Ellis said sourly. He was now using the scale-down apparatus attached to the stereotactic hat. The scaler reduced his crude finger movements to very small changes in electrode movements. If he moved his finger half an inch, the scaler converted that to half a millimeter. Very slowly the electrodes penetrated deeper into the brain.
From the screens, Ross could lift her eyes and watch the closed-circuit TV monitor showing Ellis at work. It was easier to watch on TV than to turn around and see the
Ellis picked up the first electrode array. From where Ross stood, it looked like a single slender wire. Actually, it was a bundle of twenty wires, with staggered contact points. Each wire was coated with Teflon except for the last millimeter, which was exposed. Each wire was a different length, so that under a magnifying glass, the staggered electrode tips looked like a miniature staircase.
Ellis checked the array under a large glass. He called for more light and turned the array, peering at all contact points. Then he had a scrub nurse plug it into a testing unit and test every contact. This had been done dozens of times before, but Ellis always checked again before insertion. And he always had four arrays sterilized, though he would need only two. Ellis was careful.
At length he was satisfied. “Are we ready to wire?” he asked the team. They nodded. He stepped up to the patient and said, “Let’s go through the dura.”
Up to this point in the operation, they had drilled through the skull, but had left intact the membrane of
dura mater
which covered the brain and enclosed thespinal fluid. Ellis’s assistant used a probe to puncture the dura.
“I have fluid,” he said, and a thin trickle of clear liquid slid down the side of the shaved skull from the hole. A nurse sponged it away.
Ross always found it a source of wonder the way the brain was protected. Other vital body organs were well-protected, of course: the lungs and heart inside the bony cage of the ribs, the liver and spleen under the edge of the ribs, the kidneys packed in fat and secure against thick muscles of the lower back. Good protection, but nothing compared to the central nervous system, which was encased entirely in thick bone. Yet even this was not enough; inside the bone there were sac-like membranes which held cerebrospinal fluid. The fluid was under pressure, so that the brain sat in the middle of a pressurized liquid system that afforded its superb protection.
McPherson had compared it to a fetus in a water-filled womb. “The baby comes out of the womb,” McPherson said, “but the brain never comes out of its own special womb.”
“We will place now,” Ellis said.
Ross moved forward, joining the surgical team gathered around the head. She watched as Ellis slid the tip of the electrode array into the burr hole and then pressed slightly, entering the substance of the brain. The technician punched buttons on the computer console. The display screen read: “ ENTRY POINT LOCALIZED .”
The patient did not move, made no sound. The brain could not feel pain; it lacked pain sensors. It was one of the freaks of evolution that the organ which sensed pain throughout the body could feel nothing itself.
Ross looked away from Ellis toward the X-ray screens. There, in harsh black and white, she saw the crisply outlined white electrode array begin its slow, steady movement into the brain. She looked from the anterior view to the lateral, and then to the computer-generated images.
The computer was interpreting the X-ray images by drawing a simplified brain, with the temporal-lobe target area in red and a flickering blue track showing the line the electrode must traverse from entry point to the target area. So far, Ellis was following the track perfectly.
“Very pretty,” Ross said.
The computer flashed up triple coordinates in rapid succession as the electrodes went deeper.
“Practice makes perfect,” Ellis said sourly. He was now using the scale-down apparatus attached to the stereotactic hat. The scaler reduced his crude finger movements to very small changes in electrode movements. If he moved his finger half an inch, the scaler converted that to half a millimeter. Very slowly the electrodes penetrated deeper into the brain.
From the screens, Ross could lift her eyes and watch the closed-circuit TV monitor showing Ellis at work. It was easier to watch on TV than to turn around and see the
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