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Biomedical subjects

A W Morrison

Publications and source records attributed to A W Morrison.

17 recordsLinked to original sources
PubMed1991

Bilateral cerebellopontine angle tumors in neurofibromatosis type 2.

In a series of over 500 cases of cerebellopontine angle tumors, 19 patients had bilateral neurinomas. Four of these tumors arose from the facial rather than the acoustic nerve. A conservative policy regarding surgery had been adopted in an effort to prevent hearing loss for as long as possible. Nevertheless, all patients operated on in this series are now totally deaf. The results of managing these patients surgically and conservatively are discussed.

Adult↗
PubMed1990

Hearing conservation in acoustic neuroma surgery via the posterior fossa.

An increasing number of patients with an acoustic neuroma present with useful hearing in the tumour ear. Surgical removal of these tumours via the posterior fossa route may enable preservation of the cochlear nerve and otic capsule without increasing the morbidity to the facial nerve. The results of treating 51 cases of acoustic neuroma via the posterior fossa is presented. Forty four tumours measured less than 20 mm in diameter in the cerebellopontine angle and surgery was undertaken with hearing preservation as a principle objective. In 26 cases, the cochlear nerve was preserved anatomically and post-operative hearing at levels better than mean pure tone threshold of 50 dB or 50 per cent speech discrimination was recorded in 14 patients. The preservation of hearing represents a worthwhile surgical goal in selected patients with an acoustic neuroma without increasing the operative morbidity.

Cochlear Nerve↗
PubMed1990

Primary facial nerve tumors within the skull.

In a series of 527 cerebellopontine angle tumors, there were 416 cases of acoustic nerve tumors and 14 cases of primary tumor of the facial nerve in the petrous bone or intracranial cavity. Six additional patients were presumed to have facial tumors, although they were not operated on. Of the 14 verified facial nerve tumors, all but two were neurinomas and 11 had important intracranial extensions into the middle and/or the posterior fossa. In most of these 14 cases, surgical removal was performed via the translabyrinthine route, which is advantageous in that it displays the characteristic relationship of the tumor to the facial nerve, and facilitates nerve repair. The clinical and radiological features of these facial nerve lesions are discussed and also the indications for surgical treatment which, as the unoperated cases illustrate, is not always necessary.

Adolescent↗
PubMed1989

Epidermoid and cholesterol cysts in the apex of the petrous bone.

Cystic lesions in the petrous apex are nearly always either epidermoid cysts, with a soft but solid content, or cholesterol cysts, containing brown fluid. They may be symptomless, produce progressive cranial nerve palsies or, occasionally, reach the CSF pathways thus leading either to meningitis or a CSF leak. Thirteen cases and four unverified cases have been encountered amongst a series of more than 500 cerebellopontine angle tumours. Their clinical features, radiological diagnosis and difficulties of surgical approach are discussed.

Adult↗
PubMed1988

'Otology at the crossroads' (the second Morell MacKenzie address).

It is an honour for an otological surgeon to be asked to deliver the second Sir Morell MacKenzie address. Thank you for the invitation and for that honour. Exactly 100 years ago MacKenzie, with Norris Wolfenden, founded 'The Journal of Laryngology and Rhinology'. 'Otology' was not added to the title until 1892, the year MacKenzie died. I shall return to this theme later. It is also exactly 100 years since, in 1887, MacKenzie was asked by Queen Victoria to examine her son-in-law, Frederick, Crown Prince of Germany. The controversy and subsequent recrimination which flowed from the management of Frederick's laryngeal lesion I shall leave to future lecturers to assess. It is as the founder of British laryngology that he should be remembered. As early as 1863 he had started the Metropolitan Free Dispensary for Diseases of the Throat and Loss of Voice, the first institution of its kind in the world. He wrote authoritatively on diseases of the throat and invented many instruments for the difficult art of indirect laryngeal and pharyngeal surgery. He received his Knighthood, also in 1887.

History, 19th Century↗
PubMed1979

Metabolic investigations in Menière's disease. Preliminary findings.

The aetiology of Menière's disease is unknown but in recent years many theories have been advanced to explain the observed pathological changes. These include abnormal metabolic states, allergy and personality type. In an attempt to throw more light on this and to confirm or refute the earlier work we studied twenty-seven (fifteen male:twelve female) patients with Menière's disease who conformed to the criteria set out by the Committee of Hearing and Equilibration of the American Academy of Ophthalmology and Otolaryngology (Alford, 1972). In this series the incidence of abnormal metabolic states was no higher than that of a comparable group in the general population. There was no significant difference in response to pin prick skin tests compared with a control group. Klockhoff and Lindblom's (1966) glycerol dehydration test was applied to twenty-one patients. The response to this test was measured by changes in the osmolality of the serum, the pure tone threshold of hearing and the maximum speech discrimination score. Continuous transtympanic electrocochleographic recordings during glycerol dehydration were carried out and in 10 patients there was a definite decrease in the negative summating potential. An electrophysiological explanation for this has been put forward and the possible use of this measurement in the diagnosis and management of Menière's disease has been discussed. The intercorrelation between these measures and their predictive value will become apparent in the future.

Action Potentials↗
PubMed1978

Acute deafness.

Explore the source record for details and available documents.

Adolescent↗
PubMed1976

The aetiology of otitis externa--a new concept.

This paper reports the results of middle ear pressure measurements on 33 patients with recurrent otitis externa and compares the results with those of 21 normal subjects. The maximum negative pressure in the control group was -50 mm. of water, while 17 patients (52%) with recurrent otitis externa recorded measurements of -100 mm. of water or more. It is postulated that chronic Eustachian tube dysfunction may interfere with the normal migration of epithelium from the tympanic membrane along the external auditory meatus leading to irritation and chronic infection. The treatment in these cases should be directed at the underlying cause of the Eustachian tube dysfunction.

Adult↗
PubMed1976

Transtympanic electrocochleography in the diagnosis of retrocochlear tumours.

Transtympanic electrocochleography has been used as a diagnostic procedure in over 250 adult patients with sensorineural deafness. No complications have been encountered. Among these patients vestibulocochlear Schwannoma (acoustic neuroma) has been confirmed in 56 ears while 11 other ears have been found to be affected by other space-occupying lesions. As a result of our observations in these patients, we would like to propose that there are at least three separate criteria to be considered in reaching or strongly suspecting a diagnosis of such pathology. These are broadening of the action potential (loss of P1), observation of a clear microphonic response, and preservation of the action potential even when using stimulus intensities which are not audible in the patients' affected ears. The merits of each of these criteria are discussed and compared with other clinical and operative findings. With the electrocochleographic techniques now employed in searching for acoustic neuromas, false negative results are rare though false positive results are still obtained.

Acoustic Stimulation↗
PubMedDate not supplied

Transtympanic electrocochleography during glycerol dehydration.

Thirteen patients with Meniere's disorder were tested using transtympanic electrocochleography during glycerol dehydration. The most common finding was a decrease in the negative summating potential and this appeared to be a more sensitive indicator of changes occurring in the cochlea than pure tone audiometry and speech discrimination. A pathophysiological explanation for this observation is offered and the possibility of using this decrease in the negative summating potential as a pointer to the prognosis of endolymphatic sac surgery is discussed.

Action Potentials↗