A complex brain test has given doctors examining Maryland Gov. Marvin Mandel their first positive confirmation that there is a physical problem of some kind inside the governor's brain.

The test - called a 16 channel electroencephalogram - showed what one doctor called "a moderate abnormality of the left side of the brain," which controls functions on the right side of the body.

The test was given as part of a four-hour diagnostic session Tuesday night. The governor was transported for the session from price George's [WORD ILLEGIBLE] Hospital in Cheverly to Bethe [WORD ILLEGIBLE] where neurologist Dr. Marvin Korem gold has his office.

The test was really the first break in a chain of medical uncertainties, of unanswerable questions and hypotheses that have surrounded Mandel since he entered Prince George's Hospital on April 6 feeling "fatigue" and severe headaches. Doctors hope that this and further tests may help explain why Mandel seems to have lost full control of his right hand; why his once-steady and confident walk has become impaired and why this man, celebrated for his grasp of obscure budgetary figures, has experienced momentary lapses of his memory.

Doctors have found Mandel's condition somewhat worse this week than it was the week before.

"The situation is this," said Koren-gold. "We are convinced there is an organic lesion, a physical thing there. The man is ill. He looks sick. He is sick. He isn't faking."

"But we don't know the reason."

"And we are dealing with an organ - the brain - locked inside a boney protective vault. It's like trying to find out the contents of a safe without opening it."

Dr. George B. Udvarhalyi, John Hopkins neurosurgeon also called in by the Mandel doctor said: "People quite often want to see black and whiin medicine but nature doesn't always work like this. There are gray [WORD ILLEGIBLE] and in dealing with the brain this is especially true."

The next steps in the case - it was also learned yesterday - are yet more facts as Prince George's General Hospital to look for a cancer in some other part of the body or some other bodily condition that could have some-how have an effect in the brain.

Unless they yield a quick answer, these tests will probably be followed with a new series of brain and spinal fluid examinations at John Hopkins University Hospital.

"These are probably what we will be recommending," Udvarbelyi said. There are many important tests that can yield information, but they cannot be rushed. They have to be done at the right time. And some tests only give information when you do them in a repeated fashion."

Six doctors - five of them eminent experts on the brain and nervour-system - have examined the governor. They are Dr. Perry Hookman, Mandel's personal physician; Drs. Korengold and Udvarhelyi, who were brought in as specialist consultants; Dr. Raymond Adams, of Harvard Medical School, Dr. Stanley Appel of Duke University and Dr. Guy McKhann, Johns Hopkins Medical School, all of whom were brought in to help determine whether Mandel could stand trial this week on corruption charges.

The judge in that case ruled yesterday that the trial would be posponded a month as the tests continue.

Korengold and Udvarhelyi had called a stroke the most probable cause of the governor's condition, a humor the next likeliest cause.Adams was "skeptical" about the cause being a stroke, but was not yet ready to name his leading candidate. Appel and McKhann were ready to name no cause at all, while agreeing that the governor is physically ill.

"And that's the way it often goes in medicine," Korengold said.

Mandel was first examined upon his hospitalization by Dr. Hookman, who suspected a neurological cause, there-fore summoned Korengold and Udvarhelyi.

Korengold - according to public records - first examined Mandel for an hour on the evening of Tuesday, April 5. He saw him again at his office - the Neurology Center in Bethesda - on the evening of the 6th.

He saw him again on Friday at the hospital, again Tuesday with Udvarhelyi and again Tuesday night at the Neurology Center, where Mandel was given the electroencephalogram.

"I hadn't seen him before, but I had seen him on TV," Korengold said. "And he looked like a sick guy talked to him at length examined him at length. You must decide in these cases by a combination of history and physical examination."

I know there are alot of skeptical people about this case.

"But he would have had to hire a coach who was a skilled neurologist to coach him to be the way he is."

"He walked with his feet a little bit apart. You do that when you have a little instability, for better balance. He doesn't swing his right arm very much when he walks, like you or I do. He tends to turn his right foot in a little bit. He's clumsy. And when he turns around he's a little awkward," Korengold said.

"You know, we give patients many tests that do not have an obvious purpose - something with an obvious out-come, if you're faking. For example, we have you put your arms up with your eyes closed.

"And when the governor did this, his right arm fell without his being aware of it. When we checked his reflexes, his right knee jerked a little more than the left. There is no way you can suppress that or increase that without the doctor being aware of it.

"When he was stuck with a pin, he said he felt it, however. A faker would have said just the opposite," he said.

"On questions, he answers with concrete facts fairly well, on abstract things with more difficulty. Again, that isn't how a faker would reply. He would try to reply poorly to everything.

"In short, everything - all the physical signs and tests and history - have all fit in so well there is no doubt in my mind ther is a focal brain lesion (abnormality)."

A "focal brain lesion" refers to some physical problem in some one focused site. The site, it is believed by the doctors, is in the left half of the brain - the left half because it is Mandel's right arm and right leg that are affected. Each half of hemisphere of the brain controls the opposite side of the body.

Moreover, the site is probably in the side of the left hemisphere; the side because that is the site of the temporal and parietal lobes that house the brain's movement centers.

There are three main explanations for the physical problem: a brain tumor, a stroke (a blood vessel impairment or blockage) or some degenerative disease, which is the least likely possibility statistically. Each of these, in turn, can have many causes.

None of the many complex tests done so far at [WORD ILLEGIBLE] since George's Hospital and the Neurology Center has show any specific cause.In fact, all had been ruled normal or negative until the brain wave tracings done Tuesday night at the Neurology Center showed some abnormalities.

To get such tracings; several electrical leads - like small antennas - are placed on the skull. They then record the electrical activity that goes on all the time inside the brain. The entire body, in fact, is a complex electrical as well as chemical system.

A similar abnormality was then spotted on the less complex brain wave tracings made earlier at Prince George's.

A brain tumor can be a benign or malignant one. A brain cyst or abscess can have the same effect as a tumor. A stroke can be an isolated instance followed by recovery and years of good health or a grim precursor of paralysis or worse.

Usually, said the doctor, a patient either begins recovering or at least gets no worse after a stroke. But a brain tumor usually causes progressive degeneration.

Hence the tone was ominous when Dr. Adams, in court Tuesday, said he doubted the presence of a stroke and thought Mandel's condition was deteriorating.

Drs. Udvarhelyi and Korengold thought yesterday that it is far too early to make any predictions.

"Dr. Korengold and I both recommended to the court that there be an angiogram [an X-ray study of dye injected into the brain's arteries] and spinal fluid studies," Udvarhelyi said.

"These tests are highly specialized. They have to be done at a specialized center like Johns Hopkins or they can be dangerous. They are not dangerous if done by people who know how to do them."

The upshot is that "we have to keep asking the questions," said Korengold.

Sometimes a brain tumor may take months to manifest itself.

"Or another test maygive us the answer tomorrow," he said.