Clinical comparison of tympanic membrane displacement with invasive intracranial pressure measurements

Abstract

A non-invasive method of assessing intracranial pressure (ICP) would be of benefit to patients with abnormal cerebral pathology that could give rise to changes in ICP. In particular, it would assist the regular monitoring of hydrocephalus patients. This study evaluated a technique using tympanic membrane displacement (TMD) measurements, which has been reported to provide a reliable, non-invasive measure of ICP. A group of 135 hydrocephalus patients was studied, as well as 13 patients with benign intracranial hypertension and a control group of 77 volunteers. TMD measurements were carried out using the Marchbanks measurement system analyser and compared between the groups. In 36 patients, invasive measurements of ICP carried out at the same time were compared with the TMD values. A highly significant relationship was found between TMD and ICP but intersubject variability was high and the predictive value of the technique low. Taking the normal range of ICP to be 10-15 mmHg, the predictive limits of the regression are an order of magnitude wider than this and therefore Vm cannot be used as a surrogate for ICP. In conclusion, TMD measurements do not provide a reliable non-invasive measure of ICP in patients with shunted hydrocephalus.

Prospective Study on Noninvasive Assessment of Intracranial Pressure in Traumatic Brain-Injured Patients: Comparison of Four Methods

“…The median pre-intubation Glasgow Coma Scale (GCS) score of the patients was 6 (range, [3][4][5][6][7][8][9][10][11][12][13][14]. The data included daily recordings of ABP, ICP, and TCD, in a total of 66 recordings.…”

“…Several methods for noninvasive assessment of ICP (nICP) have been described so far: transcranial Doppler ultrasonography (TCD) to measure cerebral blood flow velocity indices 2 ; skull vibrations 3 ; brain tissue resonance 4 or transcranial time of flight 5 ; venous ophthalmodynamometry 6 ; optic nerve sheath diameter assessment (ONSD) 7 ; sensing tympanic membrane displacement (TMD) 8,9 ; otoacoustic emissions 10 ; magnetic resonance imaging to estimate intracranial compliance 11 ; ultrasound-guided eyeball compression 12 ; and recordings of visual evoked potentials. 13 These methods are better suited for one-point assessment of instant value of ICP rather than continuous monitoring.…”

Can intracranial pressure be measured non-invasively bedside using a two-depth Doppler-technique?

“…A recent large study by Zweifel et al [14] showed that the TCD pulsatility index for non-invasive assessments of ICP is very limited. Tympanic membrane displacement (TMD) from the stapedius reflex was shown to correlate with ICP but with a wide ICP prediction interval [15]. Another audiological approach was based on the evoked distorsion product otoacoustic emissions, which correlates with ICP [16,17], but it has not been thoroughly evaluated against invasive measurements.…”

Advances in neuro-monitoring

“…Various methods such as transcranial Doppler (TCD) ultrasonography,[34] tympanic membrane displacement,[56] optic nerve sheath diameter,[78] and transcranial color-coded duplex sonography. [9] Noninvasive techniques lack the accuracy of their invasive counterparts thus they cannot be used as an alternative to the invasive techniques.…”