An Update on Tympanic Membrane Displacement:-New Measurements & New

ApplicationsRobert J. Marchbanks1, Tony Birch1 & Colin P. Please2

1 Department of Medical Physics and Bioengineering, Southampton General Hospital. 2 School of Mathematics, University of Southampton.

1. Samuel, M., Marchbanks, R.J. and Burge, D.M. (1998) Tympanic membrane displacement test in regular assessment in eight children with shunted hydrocephalus. J Neurosurg 88:983-995.2. Intracranial and Intralabyrinthine Fluids: Basic Aspect and Clinical Applications’. Editors A. Ernst, R Marchbanks, M.Samii. Springer Verlag, ISBN 3-540-60979-2, 1996.3. Klose et al (2000) Detection of a Relation Between Respiration and CSF Pulsation With an Echoplanar Technique. J of Magnetic Resonance Imaging, 11:438-444.4. Intracranial and Inner ear physiology and pathophysiology. Editors A. Reid, R Marchbanks, Whurr Publishers, ISBN 1 86156 066 4, 1998.

If you are interested in collaborating with us, or discussing the potential application of signal processing techniques to this problem, please contact us via Robert.Marchbanks@suht.swest.nhs.uk,

In addition to providing an evidence base for current clinical practice, the work undertaken will provide an insight into the causes of certain hearing and balance disorders,4

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 non-invasive measurements by studying the movement of the tympanic membrane as induced by intracranial pressure waves and in response to various stimuli. 1, 2.

The Signal Processing Challenge

We know that these intracranial pressure waves contain significant information concerning the status of the brain, for example, in the brain-injured patient. The challenge is to find the best method of analysing the pressure signals so as to extract underlying baseline pressure shifts and interactions between different types of pressure waves, and to take account of distortions. The main interaction of interest is between cerebral cardiovascular and respiratory pressure waves and how this interaction changes with posture - finding a means of analysis and visualisation will provide major clinical benefits.3

Appeal for Collaborators

We are keen to find collaborators to assist in development of these methods. We are aware that greater involvement of audiologists to support and undertake normative trials, clinical and field measurements is critical. We are also seeking support to trial user interfaces and seeking guidance as to methods of improving information extracted from the data by use of appropriate signal-processing methods.

It is believed that close collaboration between applied mathematics, clinicians and signal processing experts will provide the opportunity for publications in principal medical journals and collaborative research on an international basis.

Space Adaptation Syndrome (SAS)

We are directly involved in a joint US project commissioned by the NASA Johnson Space Center. Project E148 is to use the 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. Considerable Earth benefit may also be derived in terms of understanding the relationships between increased ICP and imbalance, headache, motion sickness, and cognitive performance.

From the NASA Photograph Archive

Cerebral Malaria:

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 to be used in a 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.

All pictures from the ‘African Malaria Partnership’ photo library. http://www.gsk.com/malaria