The Belgian said that he couldn't shake a problem that he initially suffered in the semi-finals of the 2018-19 Champions League
Former Tottenham defender Jan Vertonghen has admitted he suffered through the effects of a head injury for most of the 2019-20 season without speaking out about it.
The Belgian initially suffered the injury in the first leg of the 2018-19 Champions League semi-final against Ajax after he collided with team-mate Toby Alderweireld.
Vertonghen initially attempted to play through the injury but was unable to continue, and needed to be helped off the field.
Tottenham said after the match that Vertonghen did not suffer a concussion but the defender, now with Benfica, has revealed that the effects of that blow stayed with him for months.
"Lots of people don't know but I suffered a lot from that hit [against Ajax]: dizziness and headaches," he said in an interview with Sporza. "This is now the first time I am talking about it. I should not have continued playing, it affected me in total for nine months and that's why I couldn't bring what I wanted to on the field."
Vertonghen was in and out of the line-up for Spurs last season, sparking rumours of a feud with manager Jose Mourinho.
The defender, though, says he never had a problem with his manager and that his inability to hold down a starting spot was down to the lingering effects of his head injury.
"Everyone thought I was angry with Mourinho, but at that point I just couldn't [play]," he said of an incident when he was subbed off and appeared to be upset with his coach. "I still had a year left on my contract, so I had to play, but when I played, I played badly. Not many people knew that, that was my own choice, it is not blaming anyone.
"The fact I got benched had nothing to do with [Mourinho]. I was in a period I could not bring what I should have. I even thought he played me a lot compared to how I performed."
Vertonghen said that the two-month break he was able to take during the coronavirus lockdown helped him return to normal.
"I just didn't know what to do. It was game after game and training session after training session," Vertonghen said. "Every time there was a new impact. Then the lockdown came and I was able to rest for two months, after that it was a lot better."
The Premier League is set to discuss the implementation of concussion substitutes at a shareholders' meeting this week.