Sydney, a junior at Eden Prairie High School, died on June 15 after spending several days in the intensive care unit following the normally routine dental procedure.
"After three months of the medical examiners trying to determine why Sydney had a cardiac arrest, there is no clear cut answer," Diane Galleger wrote.
The Hennepin County medical examiner released its findings Thursday, saying Sydney Galleger's cause of death is "anoxic encephalopathy [lack of oxygen in the brain] due to cardiac arrest during dental extraction."
However, the manner of death is ruled undetermined because the it's possible medication administered during the procedure could have had an effect, the report notes.
Sydney's cause of death appeared to be "the perfect storm" of events, Diane Galleger wrote, adding, "She had a slight abnormality in her heart and signs of a viral infection on her brain. None on their own was felt to be enough to cause a cardiac arrest. Could she have had a slight reaction to the medications causing everything to misfire? Unlikely, but we will never know."
Sydney donated her organs. A 61-year-old Wisconsin man received her pancreas, a 12-year-old Minnesota girl and a 7-year-old Iowa boy each received a kidney, and a 21-year-old girl received Sydney's liver, her family wrote on CaringBridge back in July.
Sydney to be honored Thursday
Sydney's former teammates at Eden Prairie High School will honor her Thursday night at 5 p.m. at the swim and dive team's first conference meet at the new Eden Prairie Community Center pool, the CaringBridge post notes.
That pool is being named in her honor as well. A fund set up to raise money for the dedication has raised $83,795.11, Jennifer Nerison, a friend of the Gallegers, wrote on CaringBridge, which exceeded the money needed.
The remaining amount will go into the Sydney Galleger Scholarship Fund to help support the swim team and the alpine ski team, which Sydney was also part of.
A dedication ceremony is planned for the naming of Sydney's pool once the sign is complete – a date hasn't been determined, Nerison notes.