Source: Full prognosis still not known

PORT CHARLOTTE, Fla. -- Boston Red Sox prospect Ryan Westmoreland underwent brain surgery Tuesday that was successful, according to a statement from the team Tuesday night, but faces a "difficult period" in the aftermath of the five-hour operation.

A complete prognosis will not be known for a few days, a team source said, adding that the surgery "went well" for the 19-year-old Rhode Island native, who had a cavernous malformation, or angioma, removed from his brain stem.

An angioma is a congenital condition comprised of small abnormal capillaries (tiny blood vessels) that can swell and bleed. The condition, while potentially life-threatening, has a low mortality rate, but there is a risk of neurological damage that could affect a variety of functions, including movement and vision.

"Due to the complexity of this surgery, Ryan will face a difficult period initially before beginning his recovery," said the statement, attributed to Red Sox general manager Theo Epstein.

Tuesday's surgery was performed by Dr. Robert Spetzler of the Barrow Neurological Institute in Phoenix, Ariz. Spetzler is acknowledged as one of the foremost experts in the field.

Westmoreland remains in intensive care, according to the statement.

"Theo gave me a call," said manager Terry Francona, who attended both ends of split-squad exhibitions in Kissimmee and Port Charlotte. "Seems like very encouraging news, so we're obviously thrilled and thankful."

Typically it would take a few days to determine what, if any, neurological damage may have occurred, according to Dr. Joseph Maroon, the vice chairman of the Department of Neurosurgery at the University of Pittsburgh Medical Center and team neurosurgeon for the Pittsburgh Steelers.

"But [you] immediately know about paralysis, usually,'' Maroon wrote in an e-mail.

The condition was discovered, according to a team source, after Westmoreland began experiencing headaches and exhibiting other neurological symptoms, including numbness. He left the team's minor league camp on March 4, according to a statement released by the team, and was diagnosed the next day at Massachusetts General Hospital. The decision to have surgery was made after consultation with three specialists.

Westmoreland was in Arizona with his entire family, including his parents, Ron and Robin, according to a source close to the family. Chris Westmoreland, the home clubhouse manager for the Tampa Bay Rays and the player's uncle, is also among the family members present.

While the condition is relatively rare, at least three prominent members of the sports world have experienced angiomas, according to the Angioma Alliance, an organization that describes itself as a "patient-directed" network devoted to improving the lives of those who have had the condition.

Houston Astros manager Larry Dierker collapsed unconscious in the dugout on June 13, 1999 after experiencing a seizure brought on by the condition and underwent surgery two days later. He returned four weeks later and managed the Astros to a division title.

Olympic track star Florence Griffith Joyner suffocated in her sleep in September 1998, after experiencing an epileptic seizure attributed to a cavernous angioma, according to a coroner's report.

And in 2004, international bicycling star Alberto Contador suffered a seizure caused by an angioma and fell during a race. Contador, who was 21 at the time, underwent surgery; three years later he won the Tour de France, a feat he repeated two years later.

Among the minor leaguers who made the trip here to play in Tuesday night's 7-0 loss to the Rays was first baseman Anthony Rizzo, a 20-year-old who two years ago was diagnosed with Hodgkins lymphoma but has made a full recovery. Rizzo said he had become close friends with Westmoreland this spring and told WEEI.com's Alex Speier that he was in the training room with Westmoreland when the team's medical staff ran initial tests trying to determine the source of his headaches and other symptoms.

"I heard it on the way here," Rizzo said of the report on Westmoreland's surgery. "Awesome.

"The Red Sox, the last couple of years with [Jon] Lester and myself, they've gotten us to the best doctors in the world. Ryan is a tough, strong kid. We're pulling for him."

Gordon Edes covers the Red Sox for ESPNBoston.com. Follow him on Twitter.