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.