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A Toronto-area neurosurgeon who has studied the problem of concussions in hockey says he's not sure that NHL great Sidney Crosby will ever be able to recover from the severe concussion that has kept him sidelined for eight months.

Crosby told reporters Wednesday he's feeling good and getting better every day, but says he continues to grapple with concussion symptoms so he's not ready to return to play just yet.

Even if Crosby returns to hockey, Dr. Michael Cusimano, a neurologist at St. Michael's Hospital in Toronto, says he's not convinced the 24-year-old will ever be able to play the game the way he used to.

"I've said this right from the beginning: I think it's unlikely he will ever have a full recovery and be exactly the same as he was before if the symptoms have lasted this long.

"I think he's never going to be exactly the same," Cusimano told CTVNews.ca.

What sets elite players like Crosby apart from other players is not how fast they skate or how hard they can shoot the puck, Cusimano says. It's their ability to read the game, to anticipate where other players are going to be five seconds from now and to multitask.

Even after Crosby's doctors and coaches decide he's fully recovered, there will likely still be lingering problems, Cusimano predicts. The problems might not be things that most of us would notice, but for someone who relies on his balance, space perception and quick thinking as much as Crosby does, he'll likely notice things aren't quite right.

"My sense is that someone who has a concussion of that severity probably never recovers 100 per cent. I think there will always be some element that doesn't quite recover," he said.

"The fact that this has lasted so long indicates he has had a brain injury with some element of brain damage."

Damage to vestibular system of brain

Crosby's doctors told reporters Wednesday that the NHLer appears to have caused damage to his vestibular system, the area in the brain that controls balance and space perception.

Crosby told reporters Wednesday that while he is mostly free from daily symptoms, when he fully exerts himself, his headaches and other symptoms return.

Dr. Charles Tator, a neurosurgeon at Toronto Western Hospital, says eight months is a long time to still be feeling the effects of a concussion.

Tator notes that many people can recover fully from a single concussion. Sometimes that takes just days; other times it can take a couple of weeks. But with each subsequent concussion, the recovery can take longer.

"And the amount of force that is required to cause a second concussion is always less than what was needed to cause the first concussion. And the recovery is that much longer as the number of concussions goes up," Tator told CTV's Canada AM.

"It's cumulative damage."

Tator explains that there's a six-step program for recovery to determine if a player is ready to return to play.

"And from what I can determine, he's gone to step 4, which means pretty vigorous drills but without any body contact. He hasn't been able to go to step 5, which means practice with body contact and step 6 which is full game play," Tator said.

"The fact that he's gone to step 4 is pretty good. But on the other hand the fact that he's still getting symptoms after eight months…" he said, his voice trailing off.

Risk of developing CTE, depression

Tator says some players do fully recover after repeated concussions, pointing to the example of Patrice Bergeron.

He says science is still learning about the small behavioural and mood changes that come with repeated concussions. There is evidence to suggest that they can lead to a degenerative brain condition called CTE, of chronic traumatic encephalopathy.

But he also points out that that not every athlete with a history of concussions develops this condition. A recent study on four deceased CFL players with a history of concussions found that two had markers of the condition, while two did not.

Aside from CTE, there is also a strong link between repeated concussions and mood disorders, like depression, Tator adds.

"Depression is a recognized symptom after repeated concussions. We didn't know that a few years ago," he said.

He says this problem is now making headlines with the recent suicides of two NHL players, both of whom were taking medication for depression.

"So the combination of head injury, followed by depression, followed by suicide, I think we can draw the line between the dots," Tator said. "And then we have an even greater problem with concussion than we realize.

"So it is time to really come to grips with this."