Malcolm H. Stroud

Intramembranous and mesotympanic cholesteatomas associated with an intact tympanic membrane in children.

A series of 15 intramembranous (IMTC) and mesotympanic (MTC) cholesteatomas associated with intact tympanic membranes in children is presented. Clinical observations, audiometric and radiographic data, and surgical findings are correlated. A history of recurrent otitis media was obtained in 85% (13/15) of the cases, differentiating them from the usual congenital cholesteatomas. The possibility that many of these are indeed “acquired” lesions is emphasized. Hypothetical pathogenetic mechanisms are discussed. The basal cell papillary proliferation theory is considered the most attractive explanation of the development of both IMTCs and MTCs. The need for careful, prolonged, follow-up otoscopic examination of children with recurrent otitis media is stressed, if more of these lesions are to be recognized early.

Soft-Wall Reconstruction of the Posterior External Ear Canal Wall

A simple method of reconstructing a previously removed posterior ear canal with an autogenous, bilaminar membrane is described. The resulting air-filled mastoid cavity is an anatomic extension of the middle ear cleft and is separated from the ear canal by a functional barrier that is continuous with the tympanic membrane. The acoustic characteristics of an associated tympanoplasty are not significantly altered, and many of the problems that are associated with an exteriorized cavity are avoided. In contradistinction to other methods of mastoid obliteration or reconstruction, the semitransparent nature of the soft canal wall allows inspection of the underlying cavity for residual or recurrent disease. The technique can be used to repair either a newly created cavity or a previous radical (or modified radical) mastoidectomy defect. The functional results of thirty ears reconstructed in this fashion are detailed. A variable amount of soft-wall retraction was noted postoperatively in 47% of the ears; however, the long-term functional results in these cases remain satisfactory.

Pre and post-glycerol special audiometric tests battery results in endolymphatic hydrops†

The glycerol test for endolymphatic hydrops was administered to 17 patients exhibiting classical symptoms of Ménières disease. A complete battery of audiometric tests including the SISI, TTD (Rosenberg variation), ABLB, Sweep Frequency Békésy, two tests of speech discrimination (Rush Hughes and Northwestern), and air and bone conduction thresholds were administered pre and post‐glycerol ingestion in order to determine the effect of osmotic diuresis. Improvement in pure‐tone sensitivity and speech discrimination scores were most often observed. Among the special audiometric tests only the SISI scores exhibited changes, however, these could be related to the threshold changes. There were no significant differences observed in the threshold tone decay tests nor in the ABLB. The sweep frequency Békésy test revealed only the changes which were observed in pure‐tone sensitivity.

Letter: Endolymphatic hydrops and glaucoma production.

Present concepts concerning endolymphatic hydrops and glaucoma production are similar. A study was undertaken to evaluate the possibility of identifying early glaucomatous changes in patients with symptoms suggesting endolymphatic hydrops. Precise tests are available for glaucoma but lacking for endolymphatic hydrops. The results obtained indicate no correlation between the two disorders.Present concepts concerning endolymphatic hydrops and glaucoma production are similar. A study was undertaken to evaluate the possibility of identifying early glaucomatous changes in patients with symptoms suggesting endolymphatic hydrops. Precise tests are available for glaucoma but lacking for endolymphatic hydrops. The results obtained indicate no correlation between the two disorders.

Vestibular influences on internuclear ophthalmoplegia.

The syndrome of internuclear ophthalmoplegia (INO) has been recognized since the late 19th century and is fully described by Cogan, providing clinicians with a useful diagnostic tool. 2 INO is caused by a malfunction in the area of the medial longitudinal fascicle. When bilateral, the syndrome is usually considered to be due to multiple sclerosis.5 •8 When INO is unilateral, an infarct is suspected. The manifestations of INO are an adduction weakness on looking to the side opposite to the brain stem lesion with nystagmus in the abducting eye. The more the gaze is deviated from the midline, the greater the degree of anisometria. Convergence mayor may not be affected. Peripheral neural or muscular dysfunction has to be excluded.

Vestibular Dysfunctions after Midline Lesions in the Brain Stem of the Cat

After unilateral section of the vestibular nerve in the cat,? degeneration of terminal fibers occurs in the ipsilateral vestibular nuclei, but degeneration of the nuclei of the opposite side has not been found. Anatomic studies in mammals have shown that fibers from first order neurons are directed only to the ipsilateral vestibular nuclep·8 Secondary commissural fibers connect the opposite vestibular nuclei,8.17.23.37 however, in small number and in scattered distribution.P

Spontaneous positioning and postural nystagmus: a synopsis.

Spontaneous nystagmus when obvious and well marked is a useful indicator of disturbed oculomotor control. Not all cases are due to vestibular disturbance. Some causes are enumerated including congenital, cerebellar and vestibular lesions. Recording artifacts must be excluded. Positioning nystagmus can be physiological. When onset of the nystagmus is delayed or the duration persists considerably beyond completion of the positioning, then the term positional nystagmus is used. Various types and some possible causative mechanisms are briefly mentioned.

Books Reviewed: Myotatic, Kinesthetic and Vestibular MechanismsMyotatic, Kinesthetic and Vestibular Mechanisms Edited by DeRueckA.V.S., M.Sc., and KnightJulie, B.A. CIBA Foundation Symposium, 26 contributors. Cloth, xi, 331 pp. illustrated. Little, Brown and Co., Boston, 1967. Price,

Divested of technicalities, the principal contribution of the researches summarized lies in the application of the stimulusresponse technique of electrophysiology to the interpretation of extracellular (and sometimes intracellular) records of the 5 cell types mentioned previously. From skilled inspection of a mass of such data Eccles et al. conclude that all cerebellar neurones are inhibitory, and that after one or two synaptic relays all cerebellar input information, excitatory as well as inhibitory, is transformed into inhibition. The climbing fiber largely functions by sampling the inhibition generated in cerebellar cortex by the mossy fiber system. The output pattern generated in the Purkinje cells is transferred successively through deep cerebellar nuclei to brain stem centers. In the deep nuclei the exercise of inhibitory control by Purkinje elements presupposes a tonic nuclear excitatory state which the exclusively inhibitory Purkinje output works upon. The cerebellar relay to brain stem thus represents a negative image of the excitatory and inhibitory patterns existent at the same moment in cerebellar cortex.