Malformation Of External Ear Research Articles

Mandibulofacial dysostosis (Treacher Collins syndrome): a new proposal for its pathogenesis.

Acute exposure to 400 mg/kg 13-cis retinoic acid (13-cis RA, isotretinoin, Accutane) on the ninth day postfertilization in mice (a time that corresponds to the fourth week postfertilization in humans) results in malformations that characterize mandibulofacial dysostosis (MFD, Treacher Collins syndrome). Deficiencies in the infraorbital region and in the mandibular ramus and condyle, abnormalities of the secondary palate, and external ear malformations were observed. Light and scanning electron microscopic analyses of affected embryos illustrate that within 12 hours of maternal 13-cis RA treatment, markedly excessive (possibly premature) cell death occurs in regions where some of the cells are normally destined to undergo programmed cell death. Previous studies with retinoids have shown that they labilize lysosomal membranes and expand and strengthen regions of programmed cell death. Of particular interest for this study was cell death occurring in the dorsal (proximal) aspects of the maxillary and mandibular prominences of the first visceral arch, the second visceral arch, and the first visceral cleft, areas that correspond to the locations of the first and second arch ectodermal ("ganglionic") placodes and first closing membrane, respectively. The derivatives of this region are those that are severely affected in MFD. As described in previous reports from this laboratory, 13-cis RA is known to interfere with neural crest cells, resulting in major craniofacial malformations. However, the exposure times involved were earlier than those described herein. It is hypothesized that effects on the first and second arch ectodermal placodal cells at a time following the release from the neural folds of neural crest cells into the developing cranial region are of great significance in the pathogenesis of MFD. This is in contrast to the prevailing hypothesis that these malformations are the direct result of a primary interference with neural crest cells.

External Ear Malformations: Epidemiology, Genetics, and Natural History

This book, ninth in the Birth Defects Series published by The National Foundation-March of Dimes, is an excellent, thorough, and up-to-date review of external ear malformations, a birth defect with an overall incidence of 1%. The book is divided into two halves. In the first, the authors present a critical review of world literature on the epidemiology and etiology of this congenital defect. The introductory chapter on the intricate normal and abnormal morphogenesis of the branchial region is well illustrated, the constantly amazing fact being that 99% of human ears develop so perfectly. The excellence and strength of this book emerge in the second half, with the detailed analyses of the 600 children with external ear malformations in a seven-year prospective study of 56,000 pregnancies in the National Collaborative Perinatal Project (14 hospitals, 12 universities, 1959 to 1965) under the auspices of the National Institutes of Health. Many interesting

Statistical Observation of Patients with Hearing Impairment

From 1976 to 1978, 1995 patients with a hearing problems were statistically analyzed in the Department of Otolaryngology of Kumamoto University Hospital.One thousand one hundred and fifty-six had a sensorineural hearing loss. The causes of sensorineural hearing loss were Meniere's disease (7.1%), noise-induced deafness (7.0%), drug-induced deafness (4.3%), sudden deafness (4.8%), etc.; as for 60.5% of sensorineural hearing loss, the exact cause was unknown.Eight hundred and thirty nine had a conductive hearing loss. The causes of conductive hearing loss were chronic otitis media (60.0%), acute otits media (13.0%), serous otitis media (19.3%), congenital malformation of external and middle ear (3.1%), etc.

Hereditary deafness associated with branchial fistulae and external ear malformations

Hereditary deafness associated with branchial fistulae and external ear malformations

External and middle ear malformations associated with mandibulo-facial dysostosis and renal abnormalities: a case report.

External and middle ear malformations associated with mandibulo-facial dysostosis and renal abnormalities: a case report.

CONGENITAL MALFORMATION OF THE EXTERNAL AND MIDDLE EAR IN THREE PERSONS IN ONE FAMILY

With the improvement of the ear surgery, the congenital middle ear malformation, found occas-ionally in the operations, incidence of, have increased making middle ear malformation fairly common.The vast majority of the ear malformation in literature mention no obvious cause, although the etiologic consideration is very difficult to decide in malformation of any part. Logically, however, heredity must be considered to be a strong etiologic posibility.We encountered a rare case of 3 patients with the external and middle ear malformations in one family. They were a man, 39 years old, his daug-hter of 10 and his son of 9, whose bilateral deafn-ess were congenital.The otoscopic examination did not reveal any obvious inflammatory findings in their ears, but the functional examination showed the conductive deafness with the moderate impairment of perce-ptive hearing. Exploratory examinatin of the middle ear cavities of the father and son were carried out and the deformities of the stapes were observed.Stapes mobilization was performed on the father's left ear and stapes surgeries on his son's ears.The former didnot gain as better hearing as the latter.The embryologic considerations of the cases were also discussed.