said Klein. "He'd see things, he'd hear things, things that weren't actually there, of course. Well, I found a discrepancy in comparing the left and right readings of his brain waves and discovered that actually the man was hallucinating on just one side of his head."

"That's wild."

"The left eye and ear functioned normally; only the right side had visions and heard things.

"Well, all right, now, let's see." He had turned the machine on. He pointed to the waves on the fluorescent screen. "Now that's both sides together," he explained."What I'm looking for now are spiky waves"--- he patterned in the air with his index finger--- "especially waves of very high amplitude coming at four to eight per second. That's temporal lobe," he told her.

He studied the pattern of the brain wave carefully, but discovered no dysrhythmia. No spikes.

No flattened domes. And when he switched to comparison readings, the results were also negative.

Klein frowned. He couldn't understand it. He repeated the procedure. And found no change.

He brought in a nurse to attend to Regan and returned to his office with her mother.

"So what's the story?" Chris inquired.

The doctor sat pensively on the edge of his desk. "Well, the EEG would have proved that she had it, but the lack of dysrhythmia doesn't prove to me conclusively that she doesn't. It might be hysteria, but the pattern before and after her convulsion was much too striking."

Chris furrowed her brow. "You know, you keep on saying that, doc--- 'convulsion.' What exactly is the name of this disease?"

"Well, it isn't a disease," he said quietly.

"Well, what do you call it? I mean, specifically."

"You know it as epilepsy, Mrs. MacNeil."

"Oh, my God!"

Chris sank to a chair.

"Now, let's hold it," soothed Klein. "I can see that like most of the general public your impression of epilepsy is exaggerated and probably largely mythical." "Isn't it hereditary?" Chris said, wincing.

"That's one of the myths," Klein told her calmly "At least, most doctors seem to think so. Look, practically anyone can be made to convulse. You see, most of us are born with a pretty high threshold of resistance to convulsions; some with a low one; so the difference between you and an epileptic is a matter of degree. That's all. Just degree. It is not a disease."

"Then what is it--- a freaking hallucination?"

"A disorder: a controllable disorder. And there are many, many types of it, Mrs. MacNeil. For example, you're sitting here now and for a second you seem to go blank, let's say, and you miss a little bit of what I'm saying. Well, now that's a kind of epilepsy, Mrs. MacNeil. That's right.

It's a true epileptic attack."

"Yeah, well, that isn't Regan," Chris rebutted. "And how come it's happening just all of a sudden?"

"Look, we still aren't sure that's what she's got, and I grant you that maybe you were right in the first place; very possibly it's psychosomatic. However, I doubt it. And to answer your question, any number of changes in the function of the brain can trigger a convulsion in the epileptic: worry; fatigue; emotional stress; a particular note on a musical instrument. I once had a patient, for instance, who never used to have a seizure except on a bus when he was a block away from home. Well, we finally discovered what was causing it: flickering light from a white slat fence reflected in the window of the bus. Now at another time of day, or if the bus had been going at a different speed, he wouldn't have convulsed, you see. He had a lesion, a scar in the brain that was caused by some childhood disease. In the case of your daughter, the scar would be forward--- up front in the temporal lobe--- and when it's hit by a particular electrical impulse of a certain wavelength and periodicity, it triggers a sudden burst of abnormal reactions from deep within a focus in the lobe. Do you see?"

"I guess," Chris sighed, dejected. "But I'll tell you the truth, doc, I don't understand how her whole personality could be changed."

"In temporal lobe, that's extremely common, and can last for days or even weeks. It isn't rare to find destructive and even criminal behavior. There's such a big change, in fact, that two or three hundred years ago people with temporal lobe disorders were often considered to be possessed by a devil."

"They were what?"

"Taken over by the mind of a demon. You know, something like a superstitious version of split personality."

Chris closed her eyes and lowered her forehead onto a fist. "Listen, tell me something good,"

she murmured.

"Well, now, don't be alarmed. If it is a lesion, in a way she's fortunate. Then all we have to do is remove the scar."

"Oh, swell."

"Or it could be just pressure on the brain. Look, I'd like to have some X-rays taken of her skull.

There's a radiologist here in the building, and perhaps I can get him to take you right away.

Shall I call him?"

"God, yes; go ahead; let's do it."

Klein called and set it up. They would take her immediately, they told him.

He hung up the phone and began writing a prescription. "Room twenty-one on the second floor.

Then I'll probably call you tomorrow or Thursday. I'd like a neurologist in on this. In the meantime, I'm taking her off the Ritalin. Let's try her on Librium for a while."

He ripped the prescription sheet from the pad and handed it over. "I'd try to stay close to her, Mrs. MacNeil. In these walking trance states, if that's what it is, it's always possible for her to hurt herself. Is your bedroom close to hers?"

"Yeah, it is."

"That's fine. Ground floor?"

"No, second."

"Big windows in her bedroom?"

"Well, one. What's the deal?"

"Well, I'd try to keep it closed, maybe even put a lock on it. In a trance state, she might go through it. I once had a---"

"---Patient," Chris finished with a trace of a wry, weary smile.

He grinned. "I guess I do have a lot of them, don't I?"

"A couple."

She propped her face on her hand and leaned thoughtfully forward. "You know, I thought of something else just now."

"And what was that?"