Acta oto-laryngologica
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Acta oto-laryngologica · Mar 1996
Comparative StudyThe pars flaccida middle ear pressure and mastoid pneumatization index.
The degree of pars flaccida retraction and the levels of mastoid pneumatization were assessed and correlated in 388 adults with intact pars tensa. Poorly pneumatized mastoids were found to be associated with retraction of pars flaccida; the poorer the pneumatization, the deeper the retraction. Well pneumatized mastoids were usually associated with normal position of the pars flaccida. ⋯ Thus, the correlation of deeper degrees of pars flaccida retractions with mastoid hypopneumatization (and vice versa) lends strength to the studies which show the mastoid pneumatic system to have a function of a passive ME pressure buffer. This observation lends further evidence as to why ears with poorly pneumatized mastoids are a priori at risk to develop complications such as SOM in adults, tympanic membrane retractions and perforations, incus necrosis or retraction pocket cholesteatoma. Ears with a large pneumatic system are hardly at such risk.
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Acta oto-laryngologica · Mar 1996
Receptorpharmacological models for the therapy of labyrinthine vertigo.
In the mammalian labyrinth, GABAA receptor subtypes are involved in the excitatory neurotransmission between the vestibular type II hair cells and the afferent neurons. Additional afferent ionophoric receptor channels, sensitive to further transmitter candidates, are discussed for both types I and II hair cells. GABA accelerates excitotoxic cell death in cortical neurons. ⋯ Moderate allosteric blockers of the GABAA receptor channel and weak inverse agonists of the benzodiazepine binding site meet some requirements for potentially successful clinical application. The suppressing action of the suitable drugs picrotoxin and flumazenil on labyrinthine nystagmus and vertigo, tested in clinical trials, supports the hypothesis that GABAA receptors are involved in vestibular neurotransmission, even in humans. The test results promise the development of a successful vestibular receptorpharmacology in the near future.