Search

To emphasize the role of computerized tomography (CT) in the etiologic work-up of stapes surgery failure.Helical high resolution CT scan of the temporal bone with axial and coronal views and multiplanar reconstructions was performed in a patient who had undergone unsuccessful stapedectomy.CT scan demonstrated a well located prosthesis, the absence of the radiological hallmarks of otosclerosis, and revealed a superior semicircular canal dehiscence (SSCD). The diagnosis of SSCD was retrospectively considered accountable for the preoperative clinical and audiometric presentation that had mimicked otosclerosis.CT is the diagnostic test of choice in elucidating stapes surgery failure (with persistent or recurrent conductive hearing loss), whereas SSCD should be systematically considered among its causes.

Chronic otitis media (COM) can be divided into two subtypes: COM with cholesteatoma (including precholesteatomatous states) is an aggressive form of otitis. Surgical treatment is mandatory because of the risk for labyrinthine or cerebromeningeal complications. CT is very important in the preoperative work-up (extension of cholesteatoma, anatomic variants). In patients who have undergone middle ear surgery, CT and presently MRI play an increasing role in the detection of recurrent or relapsing cholesteatoma. COM without cholesteatoma does not have an osteolytic potential, but may leave auditive sequelae that in selected cases may warrant surgical treatment to improve hearing. CT is useful in the etiological work-up of patients with severe hypoacusis. CT also plays an important role in cases of surgical failure, to detect a dislocation of the ossiculoplasty or impairment of the middle ear caused by fluid effusion. The objective of this paper is to specify the indications, the results and the limits of pre- and postoperative imaging in COM.

Electrophysiological and pharmacological studies have revealed that the anti-arrhythmic drugs in use today possess one, or more than one, of four classes of action. 1) A direct action on the cardiac membrane, comparable to the action of local anaesthetics on nerve, which prevents the heart responding at a high frequency, by interfering with the entry of fast depolarising (sodium) current. 2) An anti-sympathetic action, achieved either by competition with adrenoceptors or by blockade of the release of noradrenaline. 3) An action on the phase of repolarisation, which delays the exit of outward current and so prolongs the absolute refractory period. 4) An action on the slow inward current, which reduces the secondary depolarisation (the "plateau") by calcium ions. Arrhythmias become more probable as a result of many different factors, and it is shown how each of the four classes of action can eliminate one of these arrhythmogenic factors, so that a rational explanation can be given for the mode of action of the various anti-arrhythmic drugs.