This summer thousands of concert-goers will sit in the Albert Hall in London enjoying the sumptuous music of the Proms season, which started this week. They should spare a thought for the orchestral musicians serenading them. It’s an open secret that at least half are taking beta blockers to slow down racing pulses and calm nerves. What is not so widely known is that one in ten may be an avid Botox user.

This is not in an effort to look more youthful under harsh stage lights, but to treat a crippling muscle condition, which because of its career-ending potential many try to keep secret.

The condition, called dystonia, causes a rigidity in the muscles that musicians use to play instruments. It can result in claw-like hands in pianists and string players, frozen jaws in wind and brass players, and paralysed vocal cords in singers. It affects up to 10 per cent of leading musicians, but, until recently, the disorder was dismissed as a psychological problem.

However, recent scientific developments have challenged this and dystonia is becoming recognised as a neurological condition that affects the pathways between brain and muscle. Treatments range from Botox to relax the muscles to retraining the brain with state-of-the-art imaging techniques, giving hope to generations of sufferers.

Clive Hobday was a violinist in the BBC orchestras for 31 years before taking early retirement on medical grounds when his right arm became paralysed with focal dystonia (see panel). “It started in 1998. My right arm suddenly collapsed and my violin bow felt like a dead weight in my hand. I could see the notes on the page and my brain knew what it had to do, but my arm wouldn’t react. My fingers were like a claw around the bow. I had no delicacy or flexibility of movement. It was quite alarming.”

For four years Hobday relied on muscle relaxants in ever-increasing doses, but the situation became unsustainable. In 2005 he took early retirement, weaned himself off the drugs and embarked on a “violinis-tic” retraining programme. This entails training the body to move in different ways when playing to vary the neuropathways employed. Progress is slow but discernible.

“It is not only a question of learning new things,” Hobday says, “but forgetting the old things. I am constantly monitoring the smallest movements I make, but now I can move my bow arm with greater control and do many things I couldn’t possibly have done before.” Neurologists believe that the problem stems from “overtraining” the brain. For example, a pianist will have a larger area of his or her brain dedicated to each individual finger than a nonmusician. In a musician suffering from dystonia the brain areas for each finger overlap, the neurological signals become jumbled, and the muscles contract, causing fingers to go claw-like, or jaws to lock.

It affects only one in ten musicians but doctors are not sure why, says Karin Rosenkranz, a neurologist at University College London, who has treated more than 150 musical dystonia sufferers and collaborates closely with the Royal College of Music. “Research suggests that only the very good muscians are affected, so the amount of training may play a role, but conversely there are lots of good musicians who can play without getting dystonia. Therefore, it’s possible that the type of training, or even genetics, may play a role. There are also personality traits that you find in patients with dystonia; they are usually more obsessive,” she says.

While a Botox injection is popular because it produces swift results, Dr Rosenkranz, believes it’s not effective in all cases. Botox works by blocking contact between nerve and muscle, weakening involuntary spasms. Treatment lasts two to three months. “Botox works well but only for muscles that have specific action,” she argues. “If a muscle governs three fingers but only one is affected by dystonia, it will affect the good fingers as well as the bad. You end up with patients who cannot play before the injection, and cannot play after,” she says. She believes that retraining may be more effective in the long term.

However, many concert pianists want swift results and these come from a combination of Botox injections and the antispasm drug Tri-hexiphenadryl. Longer-lasting treatments are being pioneered at UCL and at an institution in Germany. According to Dr Hans Christian Jabusch and his team at the Institute of Music Medicine and Physiology, in Hanover, research indicates that sufferers benefit from a programme in which each muscle group relearns how to work gradually.

Dr Rosenkranz has also found this method successful and is about to publish new findings that suggest that even 15 minutes of a muscle retraining programme can be beneficial.

By connecting a piano to a computer, Dr Jabusch may even be able to catch the earliest signs of dystonia, recording infinitesimal rhythmic inconsistencies in scales and studies. As a result of this pioneering research, 85 of the 120 musicians who took part in the Hanover Institute’s recent survey remain in the profession.

Clive Hobday is surprised how widespread the problem is. When he began seeking treatment there was still a culture of secrecy among orchestral musicians fearful of losing their jobs . Today this is different: “It is less of a stigma today,” observes a relieved Hobday. “More and more people are coming forward.”

So sit back and enjoy the Prom concert. The cost of your ticket will certainly be less than the price some of the musicians before you are paying to play.

Dystonia’s musical notes

Dystonia is a brain condition that causes involuntary muscle contractions. Up to ten per cent of musicians are affected, causing claw-like hands or frozen jaws.

The different types affect 40,000 people in the UK. Focal dystonia is the most common – musicians’ dystonia and writer’s cramp come into this category.

Sufferers include Robert Schumann, the 19th-century German composer and pianist, and the concert pianist Gary Graffman, best known for playing Gershwin’s Rhapsody in Blue for the soundtrack to Woody Allen’s Manhattan.

Times recommends

• How I lost the gift of joy for a while
• How to get Coleen Rooney's post-baby body
• The A-Z of winter style rules