Tympanic Membrane Displacement (TMD)

The use of Tympanic Membrane Displacement (TMD) measurements for assessing inner ear pressure has been the subject of research over the past 15 or more years. In most people, the inner ear fluids are connected through to the intracranial fluids, so that a change in intracranial pressure (ICP) is reflected in terms of a corresponding change in inner ear pressure. Applications of the TMD technique (i.e. the MMS-11 CCFP Analyser) include screening of patients with audiovestibular disorders to investigate whether an abnormal ICP is the underlying cause.

Also accurate ICP measurements are vital for the successful treatment and monitoring of many seriously ill patients with neurological problems. The development of the ‘MMS-11 Cerebral and Cochlear Fluid Pressure (CCFP) Analyser’ by Marchbanks Measurement Systems has provided the opportunity for a number of diverse research projects where intracranial pressure needs to be assessed non-invasively.

NASA Project into Space Adaptation Syndrome (SAS)

We are working on a collaborative project with the NASA Johnson Space Centre. Project E148 is to use our TMD technique aboard the NASA Space Shuttles to investigate changes in crew-members’ intracranial pressure and any relationships with Space Adaptation Syndrome (SAS) as the astronauts adapt to zero gravity conditions and on return to Earth. Aims of this project are to better understand the pathophysiology of Space Adaptation Syndrome so that treatment and performance of astronauts could be improved.

Non-invasive TMD intracranial pressure measurements are being combined with assessments of middle ear function, ECG and continuous blood pressure. The interdependencies are to be investigated and consider in terms of cerebral fluid dynamics.

Considerable earth benefit may also be derived in terms of understanding the relationships between increased ICP and imbalance, headache, motion sickness, and cognitive performance. Furthermore, the equipment that has been designed for NASA allows for the fist time continuous intracranial pressure measurements to be undertaken by the TMD method.

Cerebral malaria project, Kenya

Each year many thousands of children suffer cerebral malaria and many of these children will die. A concerted effort is underway throughout the African Continent to more fully understand and clinically manage patients with this condition. Important objectives are the rapid differential diagnosis of cerebral malaria on patient admission and the identification of sudden increases in the intracranial pressure that inhibit blood flow to the brain and result in death.

The TMD technique is being used in a KEMRI (Kenya Medical Research Institute) cerebral malaria project based in Kilifi, Kenya, and will be used to measure intra-aural pressure waves in terms of TMD. It is expected that these pressure waves will change in a predictable manner if the mean ICP is raised, with changes in intracranial compliance and when sudden pressure increases occur. Ultimately it is intended that continuous ICP monitoring will be undertaken and this will be facilitated using the new equipment designed for the NASA project.

Studying altitude sickness on Mount Everest

Contact: Robert Marchbanks by email robert.marchbanks@suht.swest.nhs| or by telephone: 023 8079 6335.