Former Portland Timbers forward Eddie Johnson is suing the Major League Soccer team for $9.9 million, alleging that he was allowed to practice while he still had concussion symptoms.

The lawsuit was filed Wednesday in Multnomah County Circuit Court. It names the Timbers' ownership group, Peregrine Sports LLC, and members of the team's medical staff.

Johnson sustained a concussion before a game Aug. 3, 2011, and another one 11 days later, prompting the team to rule him out for the rest of the season. The lawsuit alleges that when he returned for the MLS preseason in 2012, he was still experiencing symptoms.

The native of Chester, England, retired that April after another head injury.

The lawsuit claims that Johnson suffered ''serious and permanent traumatic head and brain injuries'' that caused headaches, memory impairment, impaired balance, blurred vision, dizziness and other conditions.

''Johnson has and will continue to suffer loss of function and ability, pain, discomfort, mental suffering, anxiety, and inconvenience and interference with his normal and usual activities,'' the lawsuit said.

The Timbers said in a statement released Thursday that they would not comment specifically on the lawsuit, but said the team follows all MLS health-related protocols for players.

''Additionally, we approach head injuries with extra caution and err on the side of conservatism above and beyond official protocol when dealing with them,'' the team said. ''We have an expert staff of physicians and trainers and stand by them and their evaluations,'' the team's statement said.

Johnson played professionally in England and the United States for more than 10 years.

His career started with Manchester United and he appeared with the first team during the 2003-04 season. He played for several English clubs before moving to the United States in 2009.

He was one of the first four players signed by the Timbers for their inaugural MLS season in 2011. He appeared in seven league matches and had a goal during his time in Portland.