Officers found the 24-year-old victim on the ground next to a bench in Toothill Lane not far from the Blue Chili Thai Restaurant on Saturday 16 September at around 4.09am.
Extensive CCTV footage has been viewed to establish the victim’s movements on the night in the hope of finding his attackers.
Detectives are now encouraging any witnesses or anyone who has any information about the attack to come forward.
It is believed that the victim had been drinking at Rush Late Bar and left the venue at around 2.37am. He has engaged with an unknown group of men and women before the attack.
Detective Inspector James Oakton said: “This was a nasty and serious assault, which has left the victim in hospital. The victim is conscious and breathing but has lost his ability to speak. It is not known whether this will be temporary or permanent.
“The victim currently has a serious fracture to his skull and bleeding on the brain. We are determined to catch those responsible and taking this attack extremely seriously.
“We would encourage anyone with information who hasn’t already spoken to the police to get in touch as soon as possible. We would especially like to hear from anyone who witnessed the attack after leaving Rush or Lexis nightclub.
“We are also releasing images of an unknown group of people who were captured on CCTV shortly before and after the attack in Toothill Lane.
“While the faces of the people are unclear we believe they will know who they are. We believe they might hold vital information about what happened that night and we would urge them to get in touch with us as soon as possible.
“This incident has absolutely devastated the victim’s family and it is imperative that we find out what happened that night.”
Anyone with information can call 101 quoting incident number 0373 of 16 September, 2023 or Crimestoppers anonymously on 0800 555 111.