Scientists have devised a way of checking brain fluid levels which they say should eventually reduce the need for painful lumbar punctures.
The technology could also help astronauts
The Southampton University team say the technique, which uses headphones linked to a computer, could be particularly useful in treating children.
Existing methods for measuring pressure in the brain can be painful, hazardous and distressing, they say.
Details of the research were presented to a Physiological Society conference.
Doctors who need to measure fluid pressure currently only have the choice of carrying out a lumbar puncture - where a sample of cerebrospinal fluid that surrounds the spinal cord is removed using a needle - or surgically implanting a pressure sensor in the head.
The scientists say their research, which also involved experts in London, could offer a non-invasive aid to the diagnosis and treatment of conditions such as meningitis, head injury and sleeping disorders.
They say the technology could also help monitor raised pressure in the brain and its potentially damaging effects in patients with conditions such as high blood pressure, people undergoing coronary bypass heart surgery, or patients who are in comas.
They say it could even be used by astronauts in space. They experience changes to the fluid pressure to redistribute itself, causing space sickness and changes to understanding.
The researchers have developed a device called a cerebral and cochlear fluid pressure (CCFP) analyser.
The patient wears headphones with an earplug that is linked to a computer and monitors the fluid pressure in the brain.
The CCFP analyser monitors brain pressure activity in the cochlear aqueduct, a small channel that connects the inner ear with the brain.
Pressure waves from the brain are transferred through the minute structures within the ear and can be measured at the ear drum.
The CCFP technology was first developed in 2000, but it was only this year that the researchers discovered that brain pressure waves - which reveal fluid pressure levels in the brain - can be detected by checking a pulse in the ear, allowing precise measurements to be made.
Dr Robert Marchbanks at the University of Southampton, who also worked on the study: "It came as a complete surprise that a pulse in the ear matches exactly the pulse linked to breathing or heart rate seen when directly monitoring brain pressure."
Dr Jean-Pierre Lin, a paediatric neurologist at Guy's and St Thomas's Hospitals in London, who helped develop the CCFP analyser, said: "It's usually very difficult to know what is going on in the head without disturbing the brain, but the CCFP analyser seems to be quick, safe and reliable.
"The patient does not need to be sedated or anaesthetised, and that is a giant leap forward in the painless care of children and babies."
He added: "We usually have no idea what is going on in the brains of unconscious patients.
"Fluid administration is essential for brain function and survival, which in the first few hours after an injury, can make the difference between life and death, and life with or without disability.
"The analyser will help us make accurate decisions at a critical stage."
Dr Marchbanks added: "We routinely carry out ECGs to monitor the health of the heart. We should be able to do the same for brain pressure."