Indications for surgery for Bell's palsy

Transmastoid surgical decompression of the facial nerve was found to have no positive effect in recovery from facial nerve function in patients with Bell's palsy. Since the risks of such surgery are greater than the benefits, this procedure should not be performed on patients with Bell's palsy unless a tumor is suspected. A mass lesion is suspected if there is complete paralysis and loss of response to evoked electromyography within the first 2 weeks after onset of the palsy or if there is recurrent facial paralysis on the same side. Rehabilitation surgical procedures should be reserved for patients with acute Bell's palsy with keratitis unresponsive to medical therapy or for those seen late in the course of the disease to correct undesirable sequelae.     

Normal threshold of hearing for cat for free-field listening

Summary A new normal threshold of hearing of cat (monoaural) for free field listening was determined by behavioural audiometry and this was compared with cat's hearing thresholds obtained by other techniques of behavioural audiometry. The absolute hearing thresholds obtained in the present study are slightly lower than those of other authors at many test frequencies. This appears to be due to different conditioning techniques and testing methods which are used to determine hearing thresholds. Any large interindividual variability in absolute hearing threshold at any test frequency resulted from differences in the technique and method of obtaining the thresholds and not from differences in hearing ability of the animals.

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Zusammenfassung An einseitig labyrinthektomierten Katzen wurde nach push-pull Konditionierung verhaltensaudiometrisch die normale Hörschwelle im freien Schallfeld bestimmt und mit den durch andere Methoden der Verhaltensaudiometrie ermittelten Katzenhörschwellen verglichen. Die in den vorliegenden Untersuchungen gefundenen absoluten Hörschwellen sind in vielen Prüffrequenzen geringgradig niedriger als die. von- anderen Autoren bestimmten. Das dürfte eine Folge der verschiedenen Konditionierungstechniken und Prufmethoden sein, die bei der Restimmung der Hörschwelle benutzt wurden. Die hier verwendete Technik der Verhaltensaudiometrie ermöglicht es, daß die Katze auf den schwächsten Schallreiz reagiert. Nach einem ausreichenden Konditionierungstraining lag bei den Audiogrammen aller Katzen eine auffallende Übereinstimmung vor (interindividuelle Übereinstimmung). Größere interindividuelle Abweichungen der absoluten Hörschwelle dürften also auf unterschiedliche Prüfmethoden und Konditionierungstechnik der Hörschwellenbestimmung und nicht auf Unterschiede in der Hörfähigkeit der Katzen zurückzuführen sein.

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Part of a Thesis approved by the University of London for the Ph. D. Degree in Medicine, 1969.     

Screening for middle-ear disease in schools for hearing-impaired children

The aim of the study was to determine the prevalence of middle-ear dysfunction in a group of hearing-impaired children attending schools for the deaf. Two groups of subjects between the ages of 4 and 16 years were selected. Group 1 consists of Caucasian and Group 2 of Negroid children. Otoscopic examinations, impedance and pure tone testing were performed on each child. The results indicated a prevalence of 43% failures on the impedance tests in the Caucasian group and 18% failures in the Negroid group. Chronic problems like perforations, otorrhoea, etc. were more common in Group 2. The results also suggest the existence of differences in the prevalence of middle-ear dysfunction between normal and hearing-impaired children.     

A technique for reembedding celloidin sections for electron microscopy

A new technique for reembedding celloidin sections of human temporal bones for transmission electron microscopy is described. It consists of four steps: 1. loosening of celloidin sections from glass slides with use of xylene and dissection of the area of interest, 2. removal of celloidin with use of clove oil, 3. staining with 1% osmium tetroxide and 1% tannic acid, and 4. embedding in epoxy resin. Autolytic changes were seen due to poor fixation. TEM of reembedded celloidin sections of optimally fixed tissue revealed that the celloidin-embedding procedure affected ul-trastructural preservation to some degree. This included less well-preserved cell membranes and some increased electron density of the cytosol decreasing the EM resolution of intracytoplasmic organelles. The technique allows TEM analysis of the intact labyrinth at all regions in the same specimen without dissection of the fragile tissue components of the membranous labyrinth. This might make the technique useful for processing freshly fixed human inner ear tissue and temporal bones for ultrastructural histo-pathological analysis.