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25-03-2006
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to top) Low Frequency Hearing Losses in Endolymphatic Hydrops. by Søren Vesterhauge MD DMSc, Consultant, The Private Hospital Hamlet, Copenhagen. The fluid filled inner ear is surrounded by bone except at the two windows, the round and the oval windows, which are both vital for the mechanical transmission of sound waves from the ear canal through the middle ear to the inner ear. The outer fluid of the inner ear (yellow in the figure below), the perilymphatic fluid, mainly communicates with the fluid surrounding the brain and the spinal cord (the cerebrospinal fluid = CSF) through a tiny canal, the cochlear aqueduct. The inner fluid compartment, the endolymphatic space (blue in the figure below), has no direct communication with the CSF, but a small sac (the endolymphatic sac) is placed between the membrane surrounding the brain (dura mater) and the bone surrounding the inner ear (the petrous part of the temporal bone). This sac connects to the perilymphatic space through a canal in another tiny bony canal, the endolymphatic duct. The pressure of the CSF changes with the position of your body and with the changes in pressure of the veins of the brain. So when it happens, it is important that the pressure alteration in the perilymphatic fluid compares to those pressure alterations of the endolympatic fluid. If not, it will result in a tension of the membrane between the two spaces, the endolymphatic membrane. In the normal ear there is a balance of the impedances (resistances) of the connections between the two compartments of the inner ear on one side and the CSF on the other side.
Figure
1. Model of the inner ear fluid compartments. Further the production of endolymph in the inner ear must be at a size of order that it doesn’t cause any increase or decrease of the endolymphatic pressure and the two windows of the inner ear to the middle ear must be water tight, so that a loss of perilymph to the middle ear will not cause any pressure changes of the inner ear. Under these circumstances of balances pressures of the two inner ear compartment, the endolymphatic membrane will neither distend nor collapse. This is vital for the function of the inner ear sensory organs for hearing and balance. In some ears this balance of pressures is disrupted, could be because of a perilymph leak to the middle ear, a high production of endolymph or a loss of balance of the pressure transmission from the CSF to the two separate inner ear compartments – or for reasons we simply don’t know. We don’t know much about collapses of the endolymphatic system, but we know for sure that a distension of the endolymphatic membrane = an endolymphatic hydrops is a common cause of inner ear malfunction. It is probably seen in all cases of Menière’s disease but also in lot patients never attacked by vertigo. In those patients, a low frequency hearing loss is common as it is in Menière’s disease. Some of these patients also complain of tinnitus and some of a feeling of fullness of the ear (a feeling of pressure, sometimes painful). The German-American audiologist, Juergen Tonndorf, has provided a beautiful mechanical explanation for that, showing that a pressure load to the cochlea will have a greater impact on the apical parts of the cochlea than on the basal parts. And we know that the apical part is responsible for the low frequency hearing function. There is no single efficient treatment, probably because there is no single common mechanism behind different cases of hydrops. In some cases diuretic drugs and salt restrictions (Fuerstenberg diet) are efficient and in other case (e.g. perilymphatic leaks) they are not. In some cases a vent tube in the ear drum in association with a pressure pulse treatment (Meniett®) will improve the condition; in the case of a perilymphatic leak it will have the opposite effect. Some drugs, which are not available in all countries, (Vastarel® (trimethazidine) and Serc (betahistine)) may be helpful for the patient. And in some other cases the condition normalizes by itself, as mysteriously as it appeared.
25-03-2006 Carlos
Herraiz, M.D. PhD The endolymphatic hydrops (EH) is a histopathological condition of the inner ear with clinical manifestations in some patients. A disorder of the metabolism of endolymph and perilymph is the responsible of the atrophy of the labyrinth. Patients can show a fluctuating and progressive sensorineural hearing loss (SNHL), tinnitus, aural pressure, vertigo or unsteadiness. The presence of all these symptoms in the same patient describes the Mèniere’s Disease (MD). Pathophysiology
Clinical
course Fluctuate
and progressive SNHL The first step of cochlear disruption comes from
the acute increase in endolymph pressure. This mechanism causes two effects:
a reduction of the movement of the stapes that provokes a conductive hearing
loss, and second, displacement of the basilar and Reissner membranes that
causes a sensorineural hearing loss in the low and medium frequencies.
Initially, these changes are reversible and hearing improves after the
acute crisis. The patient show a fluctuating hearing loss. Distortion in sound perception and diplacusis are also described by the patients.
Tinnitus Aural
pressure Hyperacusis
Vertigo
and unsteadiness Clinical
entities related with EH The
MD requires the presence of the four symptoms to be diagnosed. We can
find atypical manifestations of the disease that includes only some of
these symptoms. Cochlear EH is a clinical entity where patients refer
the presence of fluctuate or progressive SNHL, tinnitus and/or aural pressure.
These symptoms can appear simultaneously or can be developed over the
time.
Delayed EH (non-idiopathic) Diseases
with MD-like symptoms but without histopathological EH Diagnosis
Auditory evaluation requires a complete study of hearing. Tonal audiometry, speech audiometry, timpanometry and the study of the stapedial reflex (cochlear recruitment) are mandatory. The otoacoustic emissions (transitory and distortion products) are sometimes the first affected test, even when a hearing loss cannot be achieved with the audiometry test. The study of auditory evoked potentials is necessary to rule out a VIII cranial nerve or central auditory pathway affection. The electrocochleography is less used but it can also be affected in the first steps of the disease. The glycerol test (an osmotic substance that reduces the labyrinth pressure and increases hearing sensation) can be used to confirm a MD disease but when it is negative, it does not rule out this disease. Vestibular evaluation requires a study of the responses after a vestibular stimulation. The videonystagmography is used to detect spontaneous nystagmus that commonly appears during an acute attack. The rotational test and the caloric testing can reflect a reduction in the function and reflectivity of the affected labyrinth. The dynamic posturography is a test that measures the balance of the patient when different conditions are applied (eyes closed, platform movement and changes in the visual environment). It is typically affected in the chronic vestibular EH or MD. Worse results are obtained when bilateral disease. Imaging. Although EH or MD does not show typical findings in the magnetic resonance, this test is mandatory to rule out other important diseases that affect the central nervous system (tumours, vascular diseases, esclerosis multiple, etc.) Treatment
Prognosis
Recommended references Antoli-Candela
F, Tapia MC. Hydrops endolinfático. Herraiz C, Tapia MC, Plaza G. Tinnitus and Ménière’s disease: characteristics and prognosis in a tinnitus clinic simple. Eur Arch Oto Rhino Laryngol (in press, march 2006) Herraiz C, Plaza G, De los Santos G. Tinnitus retraining therapy in Ménière disease. Acta Otorrinolaringol Esp 2006;57:96-100 Herraiz C, Hernandez FJ, Plaza G, De los Santos G. Long-Term Clinical Trial of Tinitus Retraining Therapy. Otolaryngol Head Neck Surg 2005;133:774-779 Committeee on Hearing and Equilibrium guidelines for the diagnosis and evaluation of therapy in Ménière’s disease (1995). American Academy of Otolaryngology-Head Neck Surgery Foundation, Inc. Otolaryngol Head Neck Surg 113: 181-5 Hagnebo C, Melin L, Larsen HC et al (1997). The influence of Vertigo, Hearing Impairment and Tinnitus on the Daily Life of Meniere Patients. Scand Audiol 26: 69-76 Havia M, Kentala E, Pyykkö I (2002). Hearing loss and tinnitus in Meniere’s disease. Auris Nasus Larynx 29: 115-119 Yardley L, Dibb B, Osborne G (2003). Factors associated with quality of life in Ménière’s disease. Clin Otolaryngol 28: 436-441 Sajjadi H. Medical management of Meniere's disease. Otolaryngol Clin North Am. 2002 Jun;35(3):581-9 Barrs DM, Keyser JS, Stallworth C et al. Intratympanic steroid injections for intractable Ménière’s Disease. Laryngoscope 2001;111:2100-2104 Herraiz C, Hernández Calvín J, Toledano A, et al. Corticoid therapy for tinnitus patients. En Proceedings of the VII International Tinnitus Seminar, Patuzzi R ed. Perth, Australia 2002:pag 86-88
05-02-2006 In order to increase information and to inform members (as well as professionals) about tinnitus and related problems we would like to discuss a specific “question of the month”. The question this month is about low pitch hearing loss (so called “hydrops”) and related low pitch tinnitus (humming), a problem often seen at the beginning of Mobus Meniere Disease but also as an isolated symptom without vertigo. We would like you to deliver the expert´s opinions about pathophysiology, the treatment and your experiences regarding this problem.
Answer by Dr. Birgit Mazurek In
our experience the diagnosis of Meniere's disease is considered in all
patients showing all of the three symptoms hearing loss, tinnitus and
vertigo. DR. Birgit Mazurek University of Berlin
Answer by Hans-Peter Zenner, MD, PhD Low-frequency
hearing loss is often attributed to an endolymphatic hydrops. A working
model to explain an endolymphatic hydrops is a resorption problem of the
endolymph in the endolymphatic sac. Because an important mechanism for
endolympathic resorption is the function of aquaporines, it is an elegant
hypothesis to think that a dysfunction of aquaporines may play a role
in the production of endolympathic hydrops. On the other hand, a production
problem of the endolymph in the stria vascularis may also be an underlying
mechanism. Hans-Peter Zenner, MD, PhD |
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General Info Tinnitus Hearing
Loss Hearing
loss is something that happens... Meniéres
disease Sudden
deafness More information about Sudden deafness will be presented
soon... Psychological
disorders combined with tinnitus
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