Motörhead concert goers may have to sign a waiver before they buy tickets. If that band were in California, they would have to wear a Proposition 65 warning on their shirts.

Why? Because they can give you brain damage, according to a Case Report published in The Lancet. Ariyan Pirayesh Islamian and colleagues from the Hannover Medical School, detail the case of a man who developed a chronic subdural hematoma (bleeding in the brain) after headbanging at a Motörhead concert.

In January 2013, a 50-year-old man came to the neurosurgical department of Hannover Medical School with a 2 week history of a constant worsening headache affecting the whole head. Although his medical history was unremarkable and he reported no previous head trauma, 4 weeks before he had been headbanging at a Motörhead concert.

Do not attend a Motörhead concert if you can't handle the beat. Credit: Motörhead

A cranial CT confirmed the man had a chronic subdural hematoma on the right side of his brain. Surgeons removed the hematoma (blood clot) through a burr hole and used closed system subdural drainage for 6 days after surgery. His headache subsided and he was well on his last examination 2 months later.

Headbanging refers to the violent and rhythmic movement of the head synchronous with rock music, most commonly heavy metal. Motörhead, undoubtedly one of the greatest rock 'n' roll bands on earth, helped to pioneer speed metal where fast tempo songs that have an underlying rhythm of 200 bpm are aspired to.

Although generally considered harmless, headbanging-related injuries include carotid artery dissection, whiplash, mediastinal emphysema, and odontoid neck fracture. This is the first reported case showing evidence that headbanging can cause "chronic" subdural hematoma.

"Even though there are only a few documented cases of subdural haematomas, the incidence may be higher because the symptoms of this type of brain injury are often clinically silent or cause only mild headache that resolves spontaneously", explains lead author Dr Ariyan Pirayesh Islamian.

"This case serves as evidence in support of Motörhead's reputation as one of the most hardcore rock 'n' roll acts on earth, if nothing else because of their music's contagious speed drive and the hazardous potential for headbanging fans to suffer brain injury."

Further studies are needed. Rock on.