A former NHL hockey player from the Twin Cities, whose career was cut short by head injuries and is part of the concussion lawsuit against the league, has died and will have his brain donated for examination.

Jeff Parker, who turned 53 a week ago and played in parts of five seasons in the NHL in the late 1980s and early 1990s, died Monday, the Hennepin County medical examiner’s office said Thursday.

His longtime partner, Melina Miller, of Minneapolis, told the Star Tribune that Parker died at Abbott Northwestern Hospital in Minneapolis from cardiopulmonary hypertension that brought on heart and lung infections.

Miller said Parker’s brain will be donated to Boston University to determine whether he suffered from the debilitating disease known as chronic traumatic encephalopathy (CTE).

The university has so far disclosed diagnosing CTE in four onetime NHL players — Minnesota Wild favorite Derek Boogaard, Reggie Fleming, Rick Martin and Bob Probert. An examination for CTE can only be done after death. Similar diagnoses have been made in many NFL veterans.

Parker, a White Bear Lake native, had been suffering memory loss and mood swings since two severe head injuries during games in 1991 ended his career at 26 years old.

He is one of many former hockey players with Minnesota connections who are among the plaintiffs in the concussion lawsuit, which was filed in federal court in the Twin Cities against the NHL.

Miller said Parker was “two different people” from the brain damage she suspects will prove to be attributed to CTE.

“He could be the sweetest guy, and then there would a side that would pop up — really worried, angry,” Miller said of her partner of 10 years and the father of their 4-year-old daughter. “It was more private, than in public. It might last two hours; it might last two days.”

In June 2016, Parker set up an interview blocks from his home with City Pages but went to the wrong location and was late.

“Forgetting stuff, not remembering doing something when I did it 15 minutes ago,” he told the Twin Cities weekly, “it’s the kind of [expletive] that happens a lot.”

Later that year, Parker joined other former hockey players and lobbied members of Congress in hopes of pressuring professional and amateur sports to tighten rules and better protect players.

“I think [the league is] turning the other cheek to it,” Parker said during that trip to Washington. “Hopefully, something is done sooner rather than later.”

Miller said this week that Parker “was so involved in wanting to forward the cause. He didn’t want this to happen to anyone else.”

Before the previous NHL season, the league announced changes to its concussion protocol, including four independent “spotters” assigned to monitor all games. If they see signs of a concussion after a play, the coach is directed to remove the player from the game. Parker said last year that he wished those rules were around back in his day.

The beginning of the abrupt end came while Parker was with the NHL’s Hartford Whalers. In 1991, the 6-foot-3 and nearly 200-pound forward hit a stanchion holding the glass to the boards and was knocked out for 5 minutes, with a cracked helmet.

He said he didn’t remember how long he took off before his next game, but he felt pressure to get back and play because he didn’t have a contract. After absorbing another hard hit roughly two weeks later, Parker lost his sense of smell and left the game forever.

Along with the ailments that ultimately led to his death, Miller added, Parker endured daily headaches and other pain from his many hockey-related injuries. Health challenges aside, Miller and Parker were in the process of moving into a home they bought in Mahtomedi when he died.

“Whenever he was in the hospital, they offered him painkillers, and he would say no,” Miller said. Despite the chronic pain, she added, “he loved the game.”

For the past several years, Parker tended bar on Rice Street in St. Paul at Lonetti’s, whose managers have been understanding in allowing Parker to take time off for medical attention.

Otherwise, his income included a $366 monthly check from the NHL and much-appreciated financial assistance from the NHL alumni fund, Miller said.

Parker, who played in a high school state championship game for White Bear Lake Mariner in 1982, was drafted that year in the sixth round by the Buffalo Sabres. He played three seasons for Michigan State University, including in 1985-86, when the Spartans won the national championship.

Parker began his pro career in 1986-87, first with the minor league Rochester Americans and then with the Sabres.

When he left hockey for good, he had logged 141 games in the NHL, with 16 goals and 19 assists.

Funeral services for Parker will be held at 11 a.m. Friday at St. Andrew’s Lutheran Church, 900 Stillwater Road, Mahtomedi, with visitation one hour prior.