Tympanic plethysmography is a simple non-invasive diagnostic technique which is used to differentiate between intra-temporal carotid aneurysms and glomus jugulare tumours and to predict the degree of extension of the tumour. It is performed by the indirect recording of volume pressure changes of pulsating tympanic masses using a pressure transducer. The volume pressure change of the pulsating mass is transmitted to the pressure transducer through a saline-filled system.

Medical technology has undergone considerable progress with the introduction of new techniques in medical diagnosis less harmful to the patient and with a reduced risk of complications. The collaboration of doctors, scientists and bioengineers has resulted in the evolution of such changes, thereby trying to replace the more aggressive or invasive diagnostic techniques. The ideal diagnostic technology is one without pain, harm or complications to the patient.

Medical diagnostic technology may be classified as invasive or noninvasive. Non-invasive diagnostic technology is either active, using an external source of energy such as ultrasound (ultrasonography) or a small dose of X-rays, as in computerized axial tomography; or passive, using the energy emitted by human structures, as in plethysmography.

Plethysmography is the recording of volume pressure changes. Oculoplethysmography is used to monitor extracranial occlusive carotid disease (Kartchner and McRae, 1973). The use of sound energy as an internal energy emitted by the human body has proved effective as a passive, non-invasive diagnostic technique (Tewfik, 1976, 1977).

Volume pressure changes of intra-temporal carotid aneurysms have been recorded, using a pressure transducer (Tewfik, 1974).

In this article the volume pressure changes of glomus jugulare tumours have been recorded and the findings compared with those obtained, and previously published, for intra-temporal carotid aneurysms. Volume pressure changes of pulsating tympanic masses may be called tympanic plethysmography. A trial of this simple non-invasive diagnostic technique for differentiating pulsating tympanic masses is here reported, together with an assessment of the technique in its ability to predict the degree of extension of glomus jugulare tumours.