Backstreet Boys star Brian Littrell opened up on his ongoing battle with his vocal cords in an unearthed clip on social media on Tuesday.

The American singer, 50, revealed he has suffered with muscle tension dysphonia (MTD) and dystonia since 2012, which often leaves him struggling to sing.

MTD is a voice disorder characterised by strained, effortful voice that can usually tire your voice and in some cases cause damage to the vocal folds if used extensively.

Dystonia is the name for uncontrolled and sometimes painful muscle movements. It’s usually a lifelong problem, but treatment can help relieve the symptoms.

Brian, who rarely speaks about the condition, detailed the crippling battle in an interview with The Seven Sees in 2015.

In the clip, he said: ‘It’s an ongoing issue. I’ve been dealing with it ever since probably mid-way through the Backstreet Boys’ New Kids On The Block tour.’

Backstreet Boys star Brian Littrell, 50, opened up on his ongoing battle with his vocal cords in an unearthed clip, from 2015, on social media on Tuesday (pictured in 2018)

The singer revealed he has suffered with muscle tension dysphonia (MTD) and dystonia since 2012, which often leaves him struggling to sing (pictured with bandmates AJ McLean, Kevin Richardson, Nick Carter, Brian and Howie Dorough L-R in 1996)

The singer revealed he has suffered with muscle tension dysphonia (MTD) and dystonia since 2012, which often leaves him struggling to sing (pictured with bandmates AJ McLean, Kevin Richardson, Nick Carter, Brian and Howie Dorough L-R in 1996)

He added: ‘That’s when the symptoms kind of came up. It’s called vocal tension dysphonia, where the muscles around my vocal cords kind of strangle me in a way and blocks the airflow.

‘It doesn’t allow your vocal cords to work properly like they should.

‘There’s also another additional thing on top of that, it’s called dystonia which is a neurological signal which your brain sends to your voice to work.’

The Backstreet Boys, consisting of Brian, AJ McLean, 47, Kevin Richardson, 53, Nick Carter, 45, and Howie Dorough, 51, are the biggest selling boy band of all time and have sold a whopping 100 million albums.

The band first formed in Florida in 1993 and they last toured Australia in 2015.

They made their name in the nineties gaining five number ones, two multi-platinum albums, two gold albums and worldwide record sales exceeding 10 million throughout their career.

In February, Backstreet Boys announced their summer 2025 residency at the iconic Sphere in Las Vegas from July 11 through the 27, making them the first pop act to play the immersive venue.

They’re bringing back their iconic 1999 album, Millennium, with a new and improved version.

In the unearthed clip, he said: 'It's an ongoing issue. I've been dealing with it ever since probably mid-way through the Backstreet Boys' New Kids On The Block tour'

In the unearthed clip, he said: ‘It’s an ongoing issue. I’ve been dealing with it ever since probably mid-way through the Backstreet Boys’ New Kids On The Block tour’

The Backstreet Boys, consisting of Brian, AJ, Kevin, Nick and Howie, are the biggest selling boy band of all time and have sold a whopping 100 million albums (pictured in 1995)

BSB is celebrating the 25th anniversary of Millennium by re-releasing the album with 25 songs, including six demos, six acoustic live songs, and a new single called Hey.

Brian shares his talented son Baylee, 22, with wife, Leighanne Wallace, 55, who he’s been married to since 2000.

The cause if MTD is not very well understood. It may be caused by irritants such as an upper respiratory infection, passive smoking, acid reflux (heartburn), excessive demand placed on your voice or stressful life events.

Often, it is likely that more than one of these factors contribute to MTD, according to the NHS.

Meanwhile, Dystonia can affect your whole body or just 1 part. It can start at any age.

Symptoms of dystonia include uncontrolled muscle cramps and spasms parts of your body twisting into unusual positions – such as your neck being twisted to the side or your feet turning inwards shaking (tremors) uncontrolled blinking.