Pulsatile tympanic membrane displacement is associated with cognitive score in healthy subjects.

To test the hypothesis that pulsing of intracranial pressure has an association with cognition, we measured cognitive score and pulsing of the tympanic membrane in 290 healthy subjects. This hypothesis was formed on the assumptions that large intracranial pressure pulses impair cognitive performance and tympanic membrane pulses reflect intracranial pressure pulses. 290 healthy subjects, aged 20-80 years, completed the Montreal Cognitive Assessment Test. Spontaneous tympanic membrane displacement during a heart cycle was measured from both ears in the sitting and supine position. We applied multiple linear regression, correcting for age, heart rate, and height, to test for an association between cognitive score and spontaneous tympanic membrane displacement. Significance was set at P < 0.0125 (Bonferroni correction.) A significant association was seen in the left supine position (p = 0.0076.) The association was not significant in the right ear supine (p = 0.28) or in either ear while sitting. Sub-domains of the cognitive assessment revealed that executive function, language and memory have been primarily responsible for this association. In conclusion, we have found that spontaneous pulses of the tympanic membrane are associated with cognitive performance and believe this reflects an association between cognitive performance and intracranial pressure pulses.

Quantifying the contribution of intracranial pressure and arterial blood pressure to spontaneous tympanic membrane displacement.

OBJECTIVE: Although previous studies have shown associations between patient symptoms/outcomes and the spontaneous tympanic membrane displacement (spTMD) pulse amplitude, the contribution of the underlying intracranial pressure (ICP) signal to the spTMD pulse remains largely unknown. We have assessed the relative contributions of ICP and arterial blood pressure (ABP) on spTMD at different frequencies in order to determine whether spTMD contains information about the ICP above and beyond that contained in the ABP. APPROACH: Eleven patients, who all had invasive ICP and ABP measurements in situ, were recruited from our intensive care unit. Their spTMD was recorded and the power spectral densities of the three signals, as well as coherences between the signals, were calculated in the range 0.1-5 Hz. Simple and multiple coherences, coupled with statistical tests using surrogate data, were carried out to quantify the relative contributions of ABP and ICP to spTMD. MAIN RESULTS: Most power of the signals was found to predominate at respiration rate, heart rate, and their harmonics, with little outside of these frequencies. Analysis of the simple coherences found a slight preference for ICP transmission, beyond that from ABP, to the spTMD at lower frequencies (7/11 patients at respiration, 7/10 patients at respiration 1st harmonic) which is reversed at the higher frequencies (2/11 patients at heart rate and its 1st harmonic). Both ICP and ABP were found to independently contribute to the spTMD. The multiple coherence reinforced that ICP is preferentially being transmitted at respiration and respiration 1st harmonic. SIGNIFICANCE: Both ABP and ICP contribute independently to the spTMD signal, with most power occurring at clear physiological frequencies-respiration and harmonics and heart rate and harmonics. There is information shared between the ICP and spTMD that is not present in ABP. This analysis has indicated that lower frequencies appear to favour ICP as the driver for spTMD.

Does the Variability of Evoked Tympanic Membrane Displacement Data (V m) Increase as the Magnitude of the Pulse Amplitude Increases?

OBJECTIVES: Evoked tympanic membrane displacement (TMD) measurements, quantified by V m, record small volume changes in the ear canal following stimulation of the acoustic reflex. V m shows a correlation with intracranial pressure (ICP) and has been proposed as an option to non-invasively measure ICP. The spontaneous pulsing of the tympanic membrane, driven by the cardiovascular pulse, may contaminate the recordings and contribute to high measurement variability in some subjects. This study hypothesised that the larger the spontaneous vascular pulse, the larger the variability in V m. MATERIALS AND METHODS: Spontaneous and evoked TMD data from each ear in the sitting and supine position were recorded from 100 healthy volunteers using the MMS-14 CCFP analyser. ECG was also recorded to identify each heartbeat. Using bespoke software written in Matlab, spontaneous data were analysed to produce average pulse amplitude (PA) waveforms and evoked data were analysed to calculate average V m and its standard deviation. Averaged spontaneous PA was plotted against V m variability and Pearson's correlation coefficient was calculated to test for a significant linear relationship. RESULTS: There was a strong positive correlation between PA and V m variability in all conditions: left sitting, r = 0.758; left supine, r = 0.665; right sitting, r = 0.755; right supine, r = 0.513. All were significant at p < 0.001. CONCLUSION: This study shows that large V m variability is associated with a large spontaneous vascular pulse. This suggests that efforts to reduce vascular pulsing from recordings, either by a subtraction technique during post-processing or ECG-gating of the evoking stimulus, may improve reliability of the V m measurement.

Refining non-invasive techniques to measure intracranial pressure: comparing evoked and spontaneous tympanic membrane displacements.

OBJECTIVE: Tympanic membrane displacements (TMDs) are used to non-invasively gauge inner-ear fluid pressure. Inner-ear fluid pressure equalizes with intracranial pressure (ICP) via the cochlear aqueduct and therefore TMDs can indirectly evaluate ICP. We studied the relationship between two TMD modalities, evoked and spontaneous. Evoked TMD is a reflex response to an auditory stimulus and the established stapes-footplate mechanism explains how evoked TMDs change with ICP. Spontaneous TMD refers to a pulsatile TMD waveform expressed in the form of pulse amplitudes (TMD-PAs), the origins of which are poorly understood. We investigated whether both modalities respond similarly to an ICP change, suggesting a common mechanism. APPROACH: ICP was manipulated in 20 healthy volunteers by a postural change from sitting (lower ICP) to supine (higher ICP). Differences between paired sitting and supine TMD results generated ΔEvoked and ΔSpontaneous values. MAIN RESULTS: Evoked TMDs became more inward on lying supine while spontaneous TMDs became more outward. There was no evidence of a correlation between ΔEvoked and ΔSpontaneous (Right ears: r = -0.38, p = 0.10, 95% CI -0.75 to 0.21; Left ears: r = 0.34, p = 0.16, 95% CI -0.17 to 0.75). SIGNIFICANCE: This suggests the stapes-footplate mechanism is not the primary mechanism explaining how spontaneous TMDs respond to changing ICP.

Reference intervals for the evoked tympanic membrane displacement measurement: a non-invasive measure of intracranial pressure.

OBJECTIVE: Evoked tympanic membrane displacement (TMD) is a non-invasive technique for assessing intracranial pressure (ICP). The aim of this study was to define reference intervals (RIs) in the healthy population. APPROACH: Measurements were made in 154 healthy adults. Results were quantified by V m, which is the most frequently described TMD measurement. Distributions were determined for sitting and supine posture. Differences between right and left ears were explored using a Wilcoxon signed-rank test. Postural changes were used to assess pressure transfer between the cerebral spinal fluid (CSF) and the perilymph. MAIN RESULTS: The range in which 95% of scores fall is -283 to 722 nl (M = 132 nl) left sitting, -232 to 623 nl (M = 97 nl) right sitting, -543 to 717 nl (M = 37 nl) left supine and -584 to 504 nl (M = -15 nl) right supine. No significant difference was seen between the left and right ears in the sitting position; a significant difference was seen in the supine position. A significant effect of posture was seen for both the left and right ears. Postural changes indicated pressure transfer between the CSF and perilymph more often in the right ear (75.3%) than the left (61.9%). Pressure transfer could not be assumed in either ear for 13.4% of participants. SIGNIFICANCE: We present the largest dataset of evoked TMD in healthy individuals and the first set of RIs for V m. A patient cohort with both invasive ICP and evoked TMD measurements is needed to validate the technique for clinical use.

Synchronous endoscopy and sonotubometry of the eustachian tube: a pilot study.

OBJECTIVE: To describe for the first time a method of recording of Eustachian tube (ET) function by simultaneous and synchronous endoscopy and sonotubometry and explore its advantages compared with the performance of these tests independently. STUDY DESIGN: Observational study. SETTING: Academic tertiary medical center. PATIENTS: Eighteen healthy subjects. INTERVENTION: Endoscopic nasopharyngoscopy with simultaneous, synchronous sonotubometry. Each subject performed three maneuvers: pronouncing the constant "k", swallowing and yawning. MAIN OUTCOME MEASURES: The number of ET opening as a fraction of all efforts to open the tube, the duration of each opening and the sound intensity recorded by sonotubometry. RESULTS: Six (35.3%) of 17 subjects used for data analysis did not open their ET during swallowing. Excluding nonopeners, the ET opened in 3 of 4 of the swallows. The average duration of opening of the ET during swallowing was 0.44 seconds. The ET does not open every time the endoscopic view notes dilation. A negative sound pressure wave was recorded in a number of instances, immediately preceding a swallow-related opening. Contraction of the tensor veli palatini muscle was essential for ET opening. CONCLUSION: Simultaneous synchronous endoscopy and sonotubometry may improve the accuracy of either performed separately as an ET function measurement tool. Sonotubometry may prevent a false-positive endoscopy (ET viewed as open but no functional patency achieved). Endoscopy can lower the threshold considered as positive for sonotubometry. A negative pressure wave recorded by sonotubometry may reflect the ET role of clearing the middle ear of secretions toward the nasopharynx. This novel measurement technique provided additional evidence that the tensor veli palatini muscle provides the final opening action of the ET.

The tympanic membrane displacement test and tinnitus: preliminary report on clinical observations, applications, and implications.

UNLABELLED: The tympanic membrane displacement test (TMDT) is an attempt to record intracranial pressure (ICP) reflective of an intracranial pulse pressure amplitude wave (IPPA) transmitted to the inner ear and tympanic membrane with a probe placed into the external ear canal. Twelve tinnitus patients, divided into two groups, who were resistant to attempts to achieve tinnitus control or relief were selected for the TMDT. The group 1 TMDT recordings were obtained on one session test date, and group 2 (n = 6) recordings were obtained sequentially on different session test dates. Patient selection with the medical audiologic tinnitus patient protocol (MATPP) identified all to have a nonpulsatile, predominantly central-type severe disabling subjective idiopathic tinnitus (SIT) resistant to attempts for tinnitus relief with instrumentation or medication. Associated complaints in all selected SIT patients included persistent ear blockage in the SIT ear, normal middle-ear function, controlled secondary endolymphatic hydrops in the SIT ear, sensorineural hearing loss of high frequency, hyperacusis, occasional vertigo, and central nervous system complaints of headache, head pressure, and cognitive interference in memory and/or speech expression. Clinical concern is for the presence of an increased ICP reflecting an idiopathic intracranial hypertension (IIH) which, if not identified and treated, may be a factor influencing the clinical course of this particular cohort of SIT patients, highlighted by persistent ear blockage and associated complaints as described. OBJECTIVES: We set out to accomplish a number of goals: (1) To identify abnormal intracranial pulse pressure (IPPA ICP) with the extracranial TMD in a preselected particular cohort of SIT patients clinically suspected (by use of the MATPP) to have an abnormal ICP (i.e., IIH); (2) to identify the abnormal IPPA ICP as a positive indicator for IIH and as a factor - not an etiology - influencing the clinical course of SIT in a preselected cohort of SIT patients; (3) to identify with the TMDT in SIT patients spontaneous nonevoked recordings of intra-aural pressure and test-retest reliability of the TMDT; (4) to identify with the TMDT levels of normal and abnormal IPPA ICP in real time in the clinical course of SIT (i.e., an objective diagnostic and treatment monitor function of the TMD targeting ICP and IIH before and after treatment); (5) to attempt to establish a correlation of treatment efficacy, targeting preand post-ICP as a manifestation of IIH, with SIT subjective tinnitus relief; (6) to identify the limitations and complications of the TMDT; and (7) to share with the reader the evolution of a new science of brain pulsatility and a technology having a clinical application for otology and neurotology complaints of hearing loss, tinnitus, ear blockage, and vertigo. The results reported in the literature complement and alter conventional medical teaching focusing on brain pulsation, absolute intracranial pressure, and brain disease. METHOD: The Southampton Tympanic Membrane Displacement Analyzer was used to record spontaneous intra-aural pressure waves in 12 SIT patients. Patients selected for the TMDT were divided into two groups: Group 1 (n = 6) recordings were obtained on one session test date, and group 2 (n = 6) recordings were obtained sequentially on different session test dates. Multiple recordings were attempted in all patients to identify test-retest reliability in both groups. An attempt for treatment and control of an elevated ICP with or without reduced cerebral compliance (CC) was recommended in 4 patients. RESULTS: With single and multiple recordings using the TMDT, the IPPA (i.e., ICP) was demonstrated to be abnormal and to fluctuate in the clinical course of 10 of the 12 predominantly central-type tinnitus patients (SIT): abnormal IIPA with reduced CC in 8 of 12 patients and normal IPPA with reduced compliance in 2 of 12. Tinnitus treatment results targeting ICP as a manifestation of IIH with Diamox were positive in the short term in 2 patients and incomplete in 3. The SIT relief is reflective of fluctuation in the ICP and the overall issue of multifactorial brain pulsatility. CONCLUSIONS: (1) The TMDT demonstrated repeated and consistent spontaneous nonevoked recordings of displacement of the tympanic membrane, reflective of intra-aural pressure, abnormal IPPA ICP in a preselected particular cohort of SIT patients clinically suspected to have an abnormal ICP (i.e., IIH). (2) Test-retest reliability of the TMDT was positive. (3) The results of the TMDT application for identification of an elevated ICP and reduced CC were positive in 10 of 12 particular preselected patients with nonpulsatile, predominantly central-type SIT resistant to attempts for tinnitus relief with instrumentation or medication. These positive findings support clinical and basic science investigations previously reported in the literature. (4) The clinical significance of these preliminary results of an elevated ICP in a particular cohort of SIT patients supports the clinical impression of the presence of an IIH and its influence on the clinical course and overall treatment of SIT. (5) A final conclusion as to the clinical significance of an elevated ICP and reduced CC for IIH and the diagnosis and treatment of tinnitus remains to be established.

The value of transcranial cerebral sonography in diagnosing neurootological disorders.

Transcranial cerebral sonography (TCCS) is a noninvasive technique that allows the clinician to detect abnormal intracranial-inner-ear fluid interactions in terms of nanoliter tympanic membrane displacements. The displacements recorded in TCCS are evoked either by the acoustic stapedius reflex or spontaneous movements generated by intracranial cardiovascular or by respiratory pressure waves transmitted through the inner ear to the stapes and thence to the tympanic membrane. Analysis of the amplitude and direction of these displacements has enabled neurosurgeons and neurologists to estimate cerebrospinal fluid pressures in patients evaluated by TCCS. This procedure allows for applications in neurootology, particularly in those patients who present with symptoms of pulsating tinnitus, dizziness and imbalance, or hearing loss. This study describes the application of TCCS tests in a series of patients whose diagnoses included perilymphatic fistula and a variety of neurological conditions such as idiopathic intracranial hypertension, type I Arnold-Chiari malformation, sigmoid sinus thrombosis, hydrocephalus, and cerebrovascular malformations. We conclude that both raised intracranial pressure and abnormal intracranial pressure waves are associated with common neurootological symptoms, including tinnitus, dizziness, and hearing dysfunction. Furthermore, TCCS is a valuable addition to neurootologists' test batteries.