N. Julien

Surgical treatment of the high jugular bulb in patients with Ménière's disease and pulsatile tinnitus.

Abstract The aim of this retrospective study was to evaluate the functional results of surgical lowering of the high jugular bulb in the treatment of patients with Ménière’s disease and pulsatile tinnitus. Fifteen patients with disabling Ménière’s disease associated with pulsatile tinnitus and a high and medial jugular bulb were included in this study. As treatment a complete mastoidectomy was performed, after which the jugular bulb was freed by an infralabyrinthine and subfacial approach. The bulb was then displaced downwards with surgical wax. Functional results of surgery were assessed by a questionnaire according to the 1995 guidelines of the United States American Academy Committee on Hearing and Equilibrium, audiometric and vestibular tests, and by magnetic resonance and computed tomographic imaging with vascular sequences. Surgical treatment was contraindicated in two cases: one had hypoplasia of the contralateral sigmoid sinus and the other a small petrous hemangioma located around the jugular bulb that was discovered peroperatively. Among the 13 patients treated by definitive surgery, attacks of vertigo were reported as disabling in 12 cases preoperatively (92%) versus 1 (8%) after surgical treatment. No significant change in hearing was observed after surgery. Tinnitus had been reported in all patients preoperatively and decreased in intensity in four (31%) and disappeared in three (23%) after surgery.

Intraoperative laryngeal nerve monitoring during thyroidectomy and parathyroidectomy: A prospective study

OBJECTIVES The aim of this study was to stimulate the recurrent laryngeal nerve during thyroidectomy or parathyroidectomy and to record the muscle responses in an attempt to predict postoperative vocal fold mobility. PATIENTS AND METHODS Intraoperative recurrent laryngeal nerve monitoring during general anaesthesia was performed by using an electrode-bearing endotracheal tube (nerve integrity monitor EMG endotracheal tube [Medtronic Xomed, Jacksonville, Flo, USA]). Two hundred and fifteen recurrent laryngeal nerves from 141 patients undergoing total thyroidectomy (n=74), hemithyroidectomy (n=63), or parathyroidectomy (n=4) were prospectively monitored. In each case, the muscle potential was recorded after stimulation of the recurrent laryngeal nerve by a monopolar probe. RESULTS The nerve stimulation threshold before and after dissection that induced a muscle response of at least 100 μV ranged from 0.1 to 0.85 mA (mean 0.4 mA). The supramaximal stimulation intensity was defined as 1 mA. The amplitude of muscle response varied considerably from one patient to another, but the similarity of the muscle response at supramaximal intensity between pre- and postdissection and between postdissection at the proximal and distal exposed portions of the nerve was correlated with normal postoperative vocal fold function. Inversely, alteration of the muscle response indicated a considerable risk of recurrent laryngeal nerve palsy, but was not predictive of whether or not this lesion would be permanent. CONCLUSIONS Recurrent laryngeal nerve monitoring with a system using surface electrodes is a simple, non-invasive technique that is just as sensitive as monitoring by intramuscular electrodes. Monitoring is helpful for initial nerve identification and is useful to determine nerve function during and after surgery, and to adapt the surgical strategy accordingly.

Increased activity of the diastrophic dysplasia sulfate transporter in otosclerosis and its inhibition by sodium fluoride.

Hypothesis This study investigates the function of the diastrophic dysplasia sulfate transporter (DTDST) in otosclerotic bone and the effect on it of sodium fluoride (NaF). Background Otosclerosis is a localized bone dystrophy with increased bone turnover. DTDST is implicated in the regulation of the bone turnover. Materials and Methods Primary cultures of cells were obtained from the stapes and external auditory canal (EAC) of 26 patients with otosclerosis and from nine control patients. Sulfate uptake was quantified under basal conditions and with NaF. The NaF signaling pathways were investigated using forskolin and verapamil. Results The relative initial rates of sulfate uptake and the apparent Vmax values were: otosclerotic stapes > EAC > control stapes = control EAC. The sulfate uptake by the otosclerotic stapes was correlated with the loss of sensorineural hearing. The amounts of DTDST mRNA (RNase protection assay) in the four subgroups did not differ. NaF (10−6M, 1 hr) inhibited sulfate uptake by the otosclerotic stapes and EAC cells but not by control samples. Conclusion The authors believe that whether the increased DTDST activity is a cause or an effect of otosclerosis, it appears to be a specific target for NaF treatment.

Is the endolymphatic K secretion electrogenic

The endolymphatic potential is assumed to result from active K transport into the endolymphatic compartment and passive K diffusion in the opposite direction. However, in several in vivo experiments, changes in the endolymphatic potential differed from those in the endolymphatic K concentration. Moreover, in in vitro experiments, a negative endolymphatic potential was observed in the presence of ouabain without K gradient between the two compartments. These observations suggest that the coupling between the K transport and the genesis of the endolymphatic potential is not tight. Several factors may separately influence the endolymphatic potential and the K transport such as the acid-base equilibrium, the integrity of Reissners membrane, the hormonal status, and the Na transport.

Ionic control of volume and pressure regulation in the labyrinth

The labyrinthine fluids, endolymph and perilymph, fill a closed cavity, i.e. the bony labyrinth. Thus, variations in the volume of these fluids are strictly correlated to pressure variations. Indeed, the inner ear is devoid of lymphatic drainage and the overflow systems are only represented by the vestibular aqueduct connected to the closed endolymphatic sac and by the cochlear aqueduct that connects the subarachnoidal spaces with the basal scala tympani and is patent in rodents. The volume of the labyrinthine fluids depends on the water movements between the blood and the perilymph on one hand, and between perilymph and endolymph on the other. Two driving forces are involved in water movements: the hydrostatic pressure, following the equation J = Lp ΔP where J is the water flow, Lp the water permeability of the endothelium or epithelium and P the hydrostatic pressure gradient; the osmotic pressure, following the equation J = −Lp σΔπ where J is the water flow, Lp the water permeability of the endothelium or epithelium, σ is the reflection coefficient for the considered ion (its value varies from 1 for impermeable ion to 0 for permeable ion), and Δπ the osmotic gradient. The osmotic pressure is raised by only permeable solutes as the concentration of proteins in the labyrinthine fluids is very low.