Kent rider Steve Mercer remains in a stable condition in hospital in Liverpool, although his wife Caroline says his condition ‘deteriorated’ in recent days.
Mercer collided with an official course car that had been attending the scene of Manx rider Dan Kneen’s fatal crash last Wednesday.
He had been travelling back to the Grandstand in the opposite direction when the incident occurred at Ballacrye.
The Jackson Racing rider was transferred to hospital in Liverpool having initially been taken to Nobles hospital on the island.
He was diagnosed with a broken heel, T12 vertebrae and larynx, as well as injuries to his neck.
Last Thursday, the 36-year-old underwent surgery on his pelvis and leg. He is unable to breathe unassisted due to the injuries to his neck and larynx.
His wife Caroline revealed in an update on social media that doctors have identified bruising and swelling to his brain stem, which is preventing the removal of his breathing tube.
‘Unfortunately Steve wasn't able to have his breathing tube removed as his condition deteriorated over the last few days, but he's being very well looked after by the critical care teams he's with,’ she said.
‘An MRI Scan has told us that he has bruising/swelling to his brain stem, which is causing problems in the passing of information from his brain to the rest of his body.
‘It is just a waiting game now to see how he recovers when the swelling goes down, but when he is awake enough I am still passing on you messages of love and support’.
Mercer called time on his racing career last year following a huge crash at the 11th Milestone.
However, he was tempted back after testing the Honda Racing Fireblade and was set to replace Ian Hutchinson in the team if the Yorkshire rider was unable to compete at the TT following his injury return.
Hutchinson recovered sufficiently to race at the North West 200 and TT but Mercer did a late deal with the Jackson Racing team to ride Honda machinery.
An investigation is underway into the shocking incident and a new red flag procedure was implemented immediately in the aftermath, stipulating that riders will no longer travel against the racing direction of the course.
On Monday, Scottish newcomer Adam Lyon was tragically killed following a crash near the 28th Milestone in the Supersport event.
Sidecar driver Tony Baker and passenger Fiona Baker-Holden were involved in a crash during Saturday's Sidecar race, but escaped with a leg fracture and soft tissue injuries respectively.
On Wednesday, Czech rider Kamil Holan came off at Greeba Castle and was taken to hospital with a suspected ankle injury.
Meanwhile, an inquest into the death of Dan Kneen opened on Thursday.