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Authors: Michael Crichton
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please.”
The X-ray machines were swung into position at the front and side of the patient’s head. Film plates were set on, locking in with a click. Ellis stepped on the floor button, and the TV screens glowed suddenly, showing black-and-white images of the skull. He watched in twoviews as air slowly filled the ventricles, outlining the horns in black.
The programmer sat at the computer console, his hands fluttering over the buttons. On his TV display screen, the words “ PNEUMOGRAPH INITIATED ” appeared.
“All right, let’s fix his hat,” Ellis said. The boxlike tubular stereotactic frame was placed over the patient’s head. Burr-hole locations were fixed and checked. When Ellis was satisfied, he injected local anaesthetic into the scalp points. Then he cut the skin and reflected it back, exposing the white surface of the skull.
“Drill, please.”
With the 2-mm drill, he made the first of the two holes on the right side of the skull. He placed the stereotactic frame—the “hat”—over the head, and screwed it down securely.
Ross looked over at the computer display. Values for heart rate and blood pressure flashed on the screen and faded; everything was normal. Soon the computer, like the surgeons, would begin to deal with more complex matters.
“Let’s have a position check,” Ellis said, stepping away from the patient, frowning critically at Benson’s shaved head and the metal frame screwed on top of it. The X-ray technician came forward and snapped the pictures.
In the old days, Ross remembered, they actually took X-ray plates and determined position by visual inspection of the plates. It was a slow process. Using a compass, protractor, and ruler, they drew lines across the X-ray, measured them, rechecked them. Now the datawere fed directly to the computer, which did the analysis more rapidly and more accurately.
All the team turned to look at the computer print-out screen. The X-ray views appeared briefly, and were replaced by schematic drawings. The maxfield location of the stereotactic apparatus was calculated; the actual location was then merged with it. A set of coordinates flashed up, followed by the notation “ PLACEMENT CORRECT .”
Ellis nodded. “Thank you for your consultation,” he said, and went over to the tray which held the electrodes.
The team was now using Briggs stainless-steel Teflon-coated electrode arrays. In the past, they had tried gold, platinum alloy, and even flexible steel strands, back in the days when the electrodes were placed by inspection.
The old inspection operations were bloody, messy affairs. It was necessary to remove a large portion of the skull and expose the surface of the brain. The surgeon found his landmark points on the surface itself, and then placed his electrodes in the substance of the brain. If he had to place them in deep structures, he would occasionally cut through the brain to the ventricles with a knife, and then place them. There were serious complications; the operations were lengthy; the patients never did very well.
Now the computer had changed all that. The computer allowed you to fix a point precisely in three-dimensional space. Initially, along with other researchers in the field, the NPS group had tried to relate deep brain points to skull architecture. They measured their landmark points from the orbit of the eye, from the meatus of the ear, from the sagittal suture. That, of course, didn’t work—people’sbrains did not fit inside their skulls with any consistency. The only way to determine deep brain points was in relation to other brain points—and the logical landmarks were the ventricles, the fluid-filled spaces within the brain. According to the new system, everything was determined in relation to the ventricles.
With the help of the computer, it was no longer necessary to expose the brain surface. Instead, a few small holes were drilled in the skull and the electrodes inserted, while the computer watched by X-ray
The X-ray machines were swung into position at the front and side of the patient’s head. Film plates were set on, locking in with a click. Ellis stepped on the floor button, and the TV screens glowed suddenly, showing black-and-white images of the skull. He watched in twoviews as air slowly filled the ventricles, outlining the horns in black.
The programmer sat at the computer console, his hands fluttering over the buttons. On his TV display screen, the words “ PNEUMOGRAPH INITIATED ” appeared.
“All right, let’s fix his hat,” Ellis said. The boxlike tubular stereotactic frame was placed over the patient’s head. Burr-hole locations were fixed and checked. When Ellis was satisfied, he injected local anaesthetic into the scalp points. Then he cut the skin and reflected it back, exposing the white surface of the skull.
“Drill, please.”
With the 2-mm drill, he made the first of the two holes on the right side of the skull. He placed the stereotactic frame—the “hat”—over the head, and screwed it down securely.
Ross looked over at the computer display. Values for heart rate and blood pressure flashed on the screen and faded; everything was normal. Soon the computer, like the surgeons, would begin to deal with more complex matters.
“Let’s have a position check,” Ellis said, stepping away from the patient, frowning critically at Benson’s shaved head and the metal frame screwed on top of it. The X-ray technician came forward and snapped the pictures.
In the old days, Ross remembered, they actually took X-ray plates and determined position by visual inspection of the plates. It was a slow process. Using a compass, protractor, and ruler, they drew lines across the X-ray, measured them, rechecked them. Now the datawere fed directly to the computer, which did the analysis more rapidly and more accurately.
All the team turned to look at the computer print-out screen. The X-ray views appeared briefly, and were replaced by schematic drawings. The maxfield location of the stereotactic apparatus was calculated; the actual location was then merged with it. A set of coordinates flashed up, followed by the notation “ PLACEMENT CORRECT .”
Ellis nodded. “Thank you for your consultation,” he said, and went over to the tray which held the electrodes.
The team was now using Briggs stainless-steel Teflon-coated electrode arrays. In the past, they had tried gold, platinum alloy, and even flexible steel strands, back in the days when the electrodes were placed by inspection.
The old inspection operations were bloody, messy affairs. It was necessary to remove a large portion of the skull and expose the surface of the brain. The surgeon found his landmark points on the surface itself, and then placed his electrodes in the substance of the brain. If he had to place them in deep structures, he would occasionally cut through the brain to the ventricles with a knife, and then place them. There were serious complications; the operations were lengthy; the patients never did very well.
Now the computer had changed all that. The computer allowed you to fix a point precisely in three-dimensional space. Initially, along with other researchers in the field, the NPS group had tried to relate deep brain points to skull architecture. They measured their landmark points from the orbit of the eye, from the meatus of the ear, from the sagittal suture. That, of course, didn’t work—people’sbrains did not fit inside their skulls with any consistency. The only way to determine deep brain points was in relation to other brain points—and the logical landmarks were the ventricles, the fluid-filled spaces within the brain. According to the new system, everything was determined in relation to the ventricles.
With the help of the computer, it was no longer necessary to expose the brain surface. Instead, a few small holes were drilled in the skull and the electrodes inserted, while the computer watched by X-ray
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