[Malformation of the internal ear and recurrent meningitis: radio-surgical correlations]. / Malformation de l'oreille interne et méningites à répétition: corrélations radio-chirurgicales.

Authors report one case of bilateral inner ear malformation in a 3 years-old child with congenital sensorineural hearing loss, recurrent meningitis and cerebro-spinal fluid leakage. This anomaly is a pseudo-Mondini's malformation with a meningocele through the oval window and a fistula of C.S.F. of the round window. A close radiological and surgical correlation support some physiopathological hypothesis about fistula between sub arachnoid space and middle ear. Authors discuss the place of high resolution computed tomography in case of congenital sensorineural learning loss.

[Fistula of the 4th endo-branchial pouch. Apropos of 4 cases]. / Fistules de la 4e poche endobranchiale. A propos de 4 cas.

The congenital fistula of the piriform sinus is a rare, often overlooked, malformation originating in the branchial pouch. More than 70 observations have been reported in the literature. The authors describe four new cases of documented fistula of the fourth endobrachial pouch. The terminology of these malformations and the different hypotheses concerning the fistular routes is given. The authors discuss their own observations and those reported in the literature in order to better define the clinical diagnosis and the request for complementary examinations for fistulae of the piriform sinus. Surgical exploration is the ultimate diagnostic and therapeutic step.

Gratings for tunable lasers: using multidielectric coatings to improve their efficiency.

The first results of a theoretical and experimental study are presented showing that a significant enhancement of the efficiency of gratings used as wavelength selectors for cw tunable lasers may be achieved with adequate dielectric coatings. It is found that, in some cases, the energy absorbed by the grating surface can be reduced by a factor >2. The output power of a cw Rh640 dye laser was practically multiplied by the same factor. It seems that holographic gratings are more adaptable than are ruled gratings to this utilization.