Lance Hohaia has branded comments by Saints chairman Eamonn McManus as “embarrassing”.
In a strongly-worded statement released last night, McManus claims Hohaia cannot have been as ill as he made out because he was able to complete a business degree.
The Saints supremo also said the club would take action to address Hohaia’s “false statement” or “the sport has no future”.
However, the former New Zealand international has hit back, telling BBC Sport it was embarrassing that McManus “would try to draw a correlation between my mental state and my university marks”.
He added: “I was provided with an outstanding tutor that I worked with weekly to help me with my assignments and did not sit the final exam due to my mental state.
“I was awarded an aggregated score on my final exam based on my previous assignments out of compassion, which allowed me to pass.”
McManus also criticised Hohaia for damaging the reputation of the club’s “highly reputable and leading medical and rugby staff”.
However, Hohaia insisted he had not criticised Saints medical staff.
“The lack of support that I felt was from management and was in reference specifically to how my retirement and the subsequent time after was handled, not how I was treated after the Grand Final incident,” he said.
“Eamonn has taken my wider statement about the club not supporting me as an attack against the entire club and the team, which is simply not the case.”
Hohaia said he wanted to raise concerns over the way concussions are “recognised, measured, analysed, tracked and treated”.
He added: “At the moment, there is a one-size-fits-all approach, which does not, in my opinion, suffice.
“It is a shame that this message has been lost in the tirade from Saints.”
Hohaia retired from rugby league last April following concussion suffered after he was punched by Wigan prop Ben Flower during the 2014 Super League Grand Final.
His statement prompted an angry response from Saints and last night (Monday) McManus entered the row, branded the World Cup winning player’s comments as “utterly false”.
McManus added: "We will not tolerate our good name and the valuable reputations and livelihoods of our top professional staff being wrongly damaged by falsehood.
"We will take all appropriate actions to redress and remedy the situation. If we do not, the sport has no future."
McManus insisted the club's "meticulously kept records" demonstrate they handled Hohaia's situation both professionally and properly.
He also claimed Hohaia cannot have been too badly affected by his illness given he successfully completed a business degree after retiring.
"This was an impressive continuing achievement, but again utterly irreconcilable with his subsequent claims as to his wellbeing," said McManus.