Audiology & Neuro-Otology
Hearing loss and tinnitus
Hearing loss describes the sudden decrease of hearing ability of the inner ear without an external cause like a middle ear infection or an acoustic trauma. The concerned person usually notices a sudden pressure drop in on ear that cannot be removed by pressure compensation. This often comes with a reduced hearing, noises may sound distorted and a permanent and whistling ear noise (tinnitus). The ear noise may also be of other quality: murmur, buzz, engine-like, et al. Even vertigo and feeling of insecurity may occur.
Ear noises of different quality, intensity and duration without decrease of hearing are labelled with the sole term tinnitus. Between the only seconds lasting ear noises and the chronic tinnitus (longer than 6 months) lies a colorful range of varieties. A huge number of reasons has to be determined by diagnostics.
Therapy of choice is an intra-venous therapy with drugs to assist the circulation on the one hand and cortisone on the other in an descending dosage regimen. Today, infusion therapy is strictly done out-patient. In mild cases one may start with a medication per oral. A hearing test control should follow, soon to change to an intravenous therapy, if the result is not proven.
As a further therapy option we offer the intra-tympanic corticosteroid therapy. Here, the medicine, liquid cortisone, is directly inserted into the tympanic cavity by a little cut through the eardrum. The eardrum cut is minimally-invasive and is done painless under local anesthesia. The intra-tympanic corticosteroid therapy is currently relatively rare in Germany but is the therapy of choice in many American centers.
Vertigo
Our sense of balance is located in the cerebellum in the posterior fossa of the skull base. It is a result of the integration of the position and movement data from the eyes, both inner ears and the “measurement sensors” in the muscle-joint-system. These three “channels” produce an ongoing stream of information for the human cerebellum and enable a reliable evaluation of the body position. The sense of balance developed firstly in evolution and therefore, is very resilient. There is not much admiration for the sense of balance in daily life. Seeing and hearing seems to be so much more important. As soon as there is a disorder of the sense of balance it becomes obvious how fundamental and astonishingly complicated the human sense of balance really is. Different illnesses, harmful substances like tobacco or alcohol, medicine (drugs), or trauma can produce disorders. The results are dizziness (vertigo) like rotational vertigo, staggering vertigo, up and down vertigo, position vertigo, positional vertigo, kinetic vertigo, etc.
The examination of vertigo symptoms is regular subject to several specialist areas: ENT-medicals (inner ear), neurologists (CNS), radiologists (imaging skull), orthopedists (cervico-spinal column), internists (cardiovascular system) and ophthalmologists.
ENT-medicals and neurologists play a prominent role in the diagnosis of vertigo.
Audiological/ neuro-otological examinations
- Tone audiometry with high-tone audiometry up to 18kHz (TA)
- Tympanometry
- Otoacoustic emissions (TEOAE u. DP)
- Auditory brainstem response (BERA)
- Video-nystagmography (VNG)
- Caloric electronystagmography (VP)
- Positional and positioning test according to Dix-Hallpike (LP)
Audiological test procedures:
In the following we will explain some of the audiological and vestibular procedures of our office.
Audiometry (define the thresholds of minimum audible with pure tone audiometry and high frequency audiometry)
This is the commonly best known form of a hearing test. Pure tones in a frequency range of 125 Hertz up to 8.000 Hertz are used to determine the individual thresholds of minimum audible. The tones a transferred by typical earphones (air conduction) and bone vibration head (bone conduction). In our office we also have high frequency audiometry up to 18.000 Hertz. With this method hearing impairments triggered by infections, acoustic traumas or acute hearing loss can be easily detected.
Impedance measurement (middle ear diagnostic)
The purpose of middle ear cavities, including eardrums, is to transmit mechanical sound waves of the air into the liquid-filled inner ear and transfer them into electrical nerve activity. This process requires a balanced air pressure between surrounding atmosphere and middle ear (so called pressure balance). Most of you know the adaption of these pressure conditions from flying or diving. Disorders of the ventilation of the nose (e.g. crooked septum), the nasopharynx (e.g. childhood polyps), constriction of the tube or illness of the middle ear can restrict the ventilation. These pressure differential (ventilation problems) can be easily judged by an impedance measurement.
An additional measurement of the stapedius reflex gives insights about the flexibility of the so called stirrup in the middle ear (e.g. relevant with otosclerosis).
OAE (otoacoustic emissions, hair cell functional test)
Otoacoustic emissions (OAE) are acoustic phenomenons that are an expression of the vibration characteristics of hearing cells (so called “hair cells”) and membranes in the healthy inner ear. These are echo-like soundwaves that die away (“emit”) into the ear canal, after a successful sound
processing via the middle ear. A highly sensitive small sensor in the ear canal allows the registration of these soundwaves without any pain. Until now, these OAE-measurements are the best examination procedure to judge hearing abilities of infants and children. In several states of the US, OAE-measurements are mandatory part of the screening tests for infants and children and also as hearing test for school enrolement. Furthermore it is applied as progress monitoring for acute hearing loss, tinnitus or noise trauma, accompanying the therapy, and also in monitoring medicine that harms the inner ear. In our office we can do the transient evoked OAE (TEOAE) as well as the distortion products (DP).
BERA (Brainstem Evoked Response Audiometry)
The electrical signals, formed in the inner ear, are “transmitted” by the acoustic nerves to the brainstem and from there are sent by the switching stations (brainstem cores) to the interbrain and the cerebral cortex. The running excitation processes in the acoustic nerves can be registered by electrodes attached to the head (similar to a EKG). Changes in the excitation (duration of the signal) allow conclusions about disorders in the areas of the acoustic nerve and the brainstem (e.g. brain tumor, acoustic neurinoma, multiple sclerosis).
Video-Nystagmography (VNG)
Our sense of balance is located in the cerebellum in the posterior fossa. It is a result of the integration of the position and movement data from the eyes, both inner ears and the “measurement sensors” in the muscle-joint-system. These three “channels” produce an ongoing stream of information for the human cerebellum and enable a reliable evaluation of the body position. (selber Text wie bei Schwindel) Movements (especially turns) of the body lead to a rising or decreasing signal intensity in the inner ear, that is eventually processed by the cerebellum. To maintain the optical orientation in space the cerebellum starts producing “instructions” from the movementinformation for the eyes. This is like stage directions for a camera man. If these stimuli are strong or lasting, the result a spontaneous – this means not consciously controllable – eye movements, that are called nystagmus. A disorder of the equilibrium organs (so called vesibular organs) can result in such eye movements even while resting and are e.g. an expression of an asymmetrically inner ear activity. These eye movements are subjectively hardly perceptible. Occasionally one fells a mild
eye flutter. These eye ball movements can be registered with so called VNG-glasses with integrated infrared camera. It allows conclusions to the cause for the balance disorders.
Caloric (thermal) electronystagmography (VP)
Not only movement stimuli let the equilibrium organ in the inner ear react with a signal rate change. Also thermal stimuli, e.g. flushing the ear canal with cold or warm water result in change of excitation. As long as these thermal stimuli act on both sides (ear canals) the result is an increase or decrease of the signal rates but in a symmetrically manner and without vertigo. It is a physiological phenomenon that can be tested for its excitability with a one-sided thermal stimulation of the ear canal (the vestibular organ in the inner ear). The asymmetric excitations transmitted to the cerebellum result in the corresponding consciously not controllable eye movements. These can be measured with the above mentioned VNG-technology. This examination allows to determine if both equilibrium organs are working symmetrically or if one side is disordered or under-excitable. Metaphorically speaking we are testing if both front wheels of a car are turning at the same speed. If one wheel jams we are drifting to one side. A pathological asymmetric excitation can be found with neuronitis vestibularis or a morbus meniere.
Positional and positioning test according to Dix-Hallpike (LP)
The equilibrium organ does not only react to changes of movement by acceleration, deceleration or change of direction but also to static positions (rest positions). A so called “otoliths-organ” in the inner ear, which is anatomically placed between cochlea and semicircular canals, contains small crystal stones. These crystals change position towards the gravitational field depending on the position of the body/head. Imagine a water bowl with small pebbles at its bottom. Depending on the positioning of the bowl the pebbles will be found on the respective deeper rim of the bottom. It is the same with the crystals/”pebbles” in our inner ear and with the given information we can determine our positioning, even in rest.
Cervical vestibular evoked myogenic potentials (cVEMP)
Supra-threshold loudness creates a muscle reflex in the neck via a certain part specific structure of the inner ear (sacculus, otolith organ). This acoustically provoked muscle excitation is labeld VEMP.
VEMP-examinations are useful within the framework of differential diagnosis and subtyping of vertigo, if hints for an otolithic involvement in disorders of the semicircular canal or an isolated otolithic dysfunction is given.
VEMP-examinations are mandatory part of the vestibular diagnostic in cases of an experts' report on vertigo and disturbance of equilibrium. Within the framework of differential diagnosis of a sound conduction damage (e.g. otosclerosis), a VEMP must be done to exclude a dehiscence of the anterior semicircular canal. Before and if necessary also after surgical interventions on the inner ear, a VEMP-examination should additionally be done to check the receptor status of the semicircular canal.