Hoping to reassure his colleagues that he is physically able to continue as minority leader, Senator Mitch McConnell released a letter on Tuesday from the attending physician of Congress declaring that an examination and tests had ruled out a stroke or seizure as causes of his recent on-camera medical episodes.

In the letter, Dr. Brian P. Monahan, the Navy rear admiral who serves as the on-site doctor in the Capitol for members of Congress and the Supreme Court, said his examination of Mr. McConnell, Republican of Kentucky — along with a brain M.R.I., an electroencephalogram study and a neurological consultation — had found no sign of a seizure disorder or stroke.

Both possibilities and others have been raised by medical professionals who watched video of Mr. McConnell inexplicably freezing up during a news conference last week as well as a similar episode at the Capitol in July.

“There is no evidence that you have a seizure disorder or that you experienced a stroke, TIA or movement disorder such as Parkinson’s disease,” the letter said, using a shorthand for transient ischemic attack, a kind of mini stroke. “There are no changes recommended in treatment protocols as you continue recovery from your March 2023 fall.”

Mr. McConnell and his aides have attributed both alarming medical episodes to lightheadedness stemming from a concussion he suffered after a serious fall at a Washington hotel in March, as well as being dehydrated at the time of his appearances. Dr. Monahan cited a similar reason when he issued a letter after Mr. McConnell’s incident last week before having examined him or conducted any tests.

With the Senate returning on Tuesday after the extended August break, Republicans will gather for the first time since Mr. McConnell’s latest public incident, which has raised quiet questions about his ability to lead Senate Republicans and spurred speculation about a possible succession. The release of the second medical note from the Capitol physician appeared to be an effort to head off any real action regarding his leadership and to show colleagues he was not hiding the true extent of his medical condition.

So far, no senator has publicly called for any discussion of Mr. McConnell’s health, and most Republicans who have spoken have been supportive of him.

“Mitch is sharp, and he is shrewd,” Senator Mike Rounds, Republican of South Dakota, said Sunday on CNN. “He understands what needs to be done. I will leave it up to him as to how he wants to discuss that with the American public. But there’s no doubt in my mind that he is perfectly capable of continuing on at this stage of the game.”

Senate Republicans are scheduled to gather on Wednesday for their first private luncheon since July.

After last week’s incident, Mr. McConnell called numerous senators to try to allay fears about his health. He told them that the incidents were clearly side effects of his fall and had only happened twice, though each time had been in front of television cameras present to record his remarks to the media.

Dr. Monahan rarely speaks in public about his job — and almost never about the medical condition of a member of Congress — strongly suggesting that the pair of brief statements he has written up about Mr. McConnell’s condition over the past few were solicited by the senator. An internal medicine, hematology and medical oncology doctor, he has served as the attending physician since 2009, when he was nominated to the post by President Barack Obama.