The 37-year-old, who is one half of the Northern Irish dance music duo Bicep, underwent surgery last week.
He revealed he was diagnosed with a non-cancerous Craniopharyngioma tumour on his pituitary gland — situated in the brain, close to the optical nerves.
After many months of tests, he underwent the operation to remove the tumour last Friday, August 9.
The operation is said to have gone well and he is recovering in hospital.
In the meantime, the Bicep CHROMA shows will be performed by Andy solo.
Posting on Instagram, McBriar said: “Towards the end of 2023, I got some intense localised headaches matched with a weird fatigue that felt new.
“I got several blood tests in spring 2024 which came back indicating that something was wrong, so my GP arranged an MRI followed by a CT scan.
“Unfortunately, they told me they had discovered a large, and pretty rare Craniopharyngioma tumour on my pituitary gland (in my brain).
“The good news is firstly, it’s almost certainly not cancerous and secondly, I’ve caught it in the earlier stages of damage.
“I’d been very lucky to get those initial blood tests followed by an MRI. Had it been much longer I might’ve lost some eyesight and a load of other problems due to the size and position of the tumour pressing on my optic nerves.
“I’ve been through many, many rounds of hospital appointments and tests since and finally had surgery on August 9.”
He added: “I decided to carry on living life and playing shows as normal and it was personally important to keep my mind busy.
“The operation went well and I’m currently recovering in hospital.
“Recovery will be at least 6-8 weeks and a long road of aftercare but I’m feeling incredibly grateful and lucky.
“I’d like to say a huge thank you to all the amazing consultants, surgeons, doctors and nurses at the NHS who have looked after me and been so amazing, kind and empathetic.
“The support I’ve received has been incredible, I can’t say this enough. Appointments were arranged with sometimes only hours’ notice and communication incredibly fast and direct.
“Our healthcare system is very precious and worth fighting for.
“Whilst I am in recovery Andy will be performing upcoming shows as Bicep solo until further notice. Thanks for understanding.
“Finally, a heartfelt thanks to my family, friends and work colleagues who have been my absolute rock through this behind the scenes.”
Bicep started out in Belfast as DJs and music bloggers and released their self-titled debut album in 2017.
It was followed by Isles in 2021, which reached No 2 in the UK album chart, and earned them two nominations at the 2021 Brit awards, for British group and breakthrough artist.
They performed at Glastonbury this year, where a Chroma set proved so popular that it had to be cancelled due to overcrowding.