Some heavy-metal fans who headbang excessively could be at risk for bleeding in the brain, say German doctors who describe a rare case of the traumatic brain injury.

In Thursday’s issue of the medical journal The Lancet, doctors say they treated a 50-year-old man with a two-week history of a constant worsening headache that affected his whole head. He had no history of head trauma or substance abuse, but reported headbanging at a Motörhead concert four weeks earlier.

We are not smartasses who advise against headbanging. - Dr. Ariyan Pirayesh Islamian

Headbanging refers to the violent and rhythmic movement of the head synchronous with rock music, most commonly heavy metal. Motörhead helped to pioneer speed metal that aspires to have an underlying rhythm of 200 bpm, the doctors said.

A cranial CT of the Motörhead fan showed right-sided chronic subdural hematoma — a collection of blood and blood breakdown products between the surface of the brain and its outermost covering or dura, according to the U.S. National Institutes of Health.

Surgeons removed the hematoma or blood clot. He stayed in hospital for six days and was discharged home after eight days. At his two-month followup, he was free of symptoms, the researchers said.

'We are not smartasses,' doctor says

"We are not smartasses who advise against headbanging," study author Dr. Ariyan Pirayesh Islamian of the Hannover Medical School in Germany said in an email. "Our purpose was not only to entertain the readership with a quite comical case report on complications of headbanging that confirms the reputation of Motörhead as undoubtedly one of the hardest rock 'n' roll bands on Earth, but to sensitize the medical world for a certain subgroup of fans that may be endangered when indulging themselves in excessive headbanging."

In a followup scan, the doctors saw the man had a benign cyst, which might have increased his vulnerability to the brain injury.

When the researchers checked the medical literature, they found just three cases of subdural hematoma attributed to headbanging, which emphasizes the rareness of the complication.

The incidence may be higher because the symptoms are often clinically silent or cause only mild, temporary headache, Islamian said.

The Motörhead patient wishes to remain anonymous and was not available for interviews, the journal said. He was treated in January 2013.