Chief Justice John Roberts suffered a seizure at his summer home in Maine on Monday, causing a fall that resulted in minor scrapes, a Supreme Court spokeswoman said.

Roberts, 52, was taken by ambulance to Penobscot Bay Medical Center in Rockport, where he underwent a “thorough neurological evaluation, which revealed no cause for concern,” spokeswoman Kathy Arberg said in a statement.

He was to remain in the hospital overnight.

“It’s my understanding he’s fully recovered,” said Christopher Burke, a spokesman for the hospital.

Roberts had a similar episode in 1993, Arberg said.

Doctors called Monday’s incident “a benign idiopathic seizure,” Arberg said. The White House described the January 1993 episode as an “isolated, idiosyncratic seizure.” Both descriptions indicate that doctors could not determine the seizure’s cause or link it to another medical condition.

Monday’s incident occurred around 2 p.m. on a dock near Roberts’ home in Port Clyde on Hupper Island.

He had just gotten off a boat and was returning home after running errands, Arberg said.

Roberts was taken by private boat to the mainland, then transferred to an ambulance, St. George Fire Chief Tim Polky said.

“He was conscious and alert when they put him in the rescue” vehicle, Polky said.

A benign seizure means that doctors performed an MRI and other tests to conclude there was no tumor, stroke or other explanation.

In addition, doctors would have quickly ruled out simple explanations such as dehydration or low blood sugar.

By definition, someone who has had more than one seizure without any other cause is determined to have epilepsy, said Dr. Marc Schlosberg, a neurologist at Washington Hospital Center, who is not involved in Roberts’ case.

Whether Roberts will need anti-seizure medications to prevent another is something he and his doctor will have to decide.

But after two seizures, the likelihood of another at some point is greater than 60 percent.

“When it’s going to occur, obviously nobody knows,” Schlosberg said.

Roberts and his wife, Jane Sullivan Roberts, bought their Maine home last year. The home is about 225 feet offshore, with a water view toward Port Clyde General Store.

Port Clyde is part of the town of St. George, which is about 18 miles south of Rockland.

Appointed by President Bush in 2005, Roberts is the youngest justice on a court in which the senior member, John Paul Stevens, is 87. Bush was informed of the hospitalization by his chief of staff, Josh Bolten, the White House said.

Roberts is the father of two young children.

Larry Robbins, a Washington lawyer who worked with Roberts at the Justice Department in 1993, said he drove Roberts to work for several months after the first incident. Robbins said Roberts never mentioned what the problem was and he never heard of it happening again.

In 2001, Roberts described his health as “excellent,” according to Senate Judiciary Committee records.

Roberts became chief justice after the death of William Rehnquist in September 2005, although Bush first had chosen him to take Sandra Day O’Connor’s seat when she announced her retirement earlier that year.

With Roberts and Justice Samuel Alito, who ultimately replaced O’Connor, on board, the court was more conservative this past term, issuing decisions that, among other things, upheld abortion restrictions and struck down public school integration plans.

He earlier served as an appellate judge in Washington and spent more than a decade before that as a lawyer at the Hogan and Hartson law firm, where he specialized in arguing cases before the Supreme Court.

Roberts also served in the Reagan and Bush administrations in the 1980s and ’90s. He was a clerk for Rehnquist after graduating from Harvard Law School.

Roberts spent a couple of weeks in Europe in July, teaching a course in Vienna and attending a conference in Paris. He was at the court in Washington late last week.