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Biomedical subjects

M H Stroud

Publications and source records attributed to M H Stroud.

At least 19 recordsLinked to original sources

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.

Connective Tissue

Vertical eye deviation and nystagmus inhibition during mental tasking.

Twenty subjects with no vestibular complaints and normal otoscopic exams were stimulated with 44 degrees C water for 5 minutes in one ear and their nystagmus was recorded by vertical and horizontal electro-oculography. Changes in vertical eye position and nystagmus inhibition were correlated during periods of mental tasking, relaxation, and voluntary eye elevation. The results showed an average of 42 degree eye depression with mental tasking during irrigation. In addition, mental arithmetic had a "releasing" effect on horizontal nystagmus. Elevation of the eyes on command, however, produced marked irregularity in the horizontal tracings, simulating inhibition. Almost every subject had an apparent vertical deflection on ENG with eye closure. These findings suggest a mechanical component to the phenomenon of inhibition as well as an active central mechanism.

Adolescent

Diaphoresis and Meniere's disease.

The effect of diaphoresis on patients with Meniere's disease (labyrinthine hydrops) previously has not been reported. With the use of two distinct activities to produce diaphoresis, we were able to document substantial transient improvements in pure-tone threshold, speech-reception threshold, and speech discrimination concurrent with a decrease in tinnitus and fullness in two patients with unilateral Meniere's disease that had been diagnosed previously by the glycerin test. The two diaphoretic activities were (1) strenuous exercise, including periodic visits to the sauna, and (2) passive activity consisting of repetitive visits to the sauna. Glycerin, an osmotic diuretic, produces similar temporary beneficial effects primarily in patients in the fluctuant hearing stage of Meniere's disease. The glycerin test is being used in several clinics as an adjunct for the diagnosis of endolymphatic hydrops.

Adult

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 Meniere's disease. A complete battery of audiometric tests including the SISI, TTD (Rosenberg variation). ABLB, Sweep Frequency Bekesy, 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 Bekesy test revealed only the changes which were observed in pure-tone sensitivity.

Acoustic Stimulation

The efficacy of "conservative" medical regimens on the rate of hearing losses in Meniere's syndrome: a retrospective computerized statistical analysis.

The records of 47 patients with Ménière's syndrome were analyzed in a retrospective computerized study to determine the effect of different medical regimens on the long term course of hearing loss. Four treatment groups, including histamine (subcutaneous), other vasodilators (oral), vitamins, and untreated controls were examined. Results suggest that there was no statistically significant difference among the four groups in the rates or absolute level of hearing loss or SRT despite different therapeutic regimens. The ability of these agents to conserve hearing in patients with Ménière's syndrome remains unproven on the basis of clinical and laboratory evidence.

Adult

Ocular motor dysfunction in total and hemicerebellectomized monkeys.

Studies of ocular motor function in monkeys undergoing either total or hemicerebellectomies has revealed the following abnormalities which can be attributed to cerebellar dysfunction: 1. Loss of smooth pursuit movements 2. Gaze-fixation nystagmus 3. Loss of inhibitory input on the vestibular apparatus reflected in a decreased latency and prolonged response to caloric stimuli. It is intimated that the role of the hemicerebellum deals with ipsilateral tone and its effect on eye movements.

Animals

Vestibular involvement in Bell's palsy.

Vestibular involvement in the acute phase of idiopathic facial paralysis (Bell's palsy) was observed in 22 percent and 14 patients. These patients were evaluated by history, physical examination and caloric tests with electronystagmography (ENG) employing the Cawthorne-Hallpike technique. Bell's palsy has been considered a mononeuropathy limited to the facial nerve. Evidence of occasional involvement of other cranial nerves (Vth and/or VIIIth) suggests a polyneuropathy. Several theories have been advanced to explain the involvement of the vestibular nerve.

Facial Paralysis

Modes of vestibular habituation.

An experiment was designed to investigate the effect of different modes of vestibular habituation. Volunteers were divided into two groups differing only in visual fixation. A theoretical explanation of the observed differences in nystagmus speed and frequency of beats between groups is offered. Secondary experiments designed to support the conclusions were performed using optokinetic stimulation with a stationary line for visual fixation. An increase in conjugate tone potential opposed to the unwanted optokinetic stimulus developed. Post-habituation nystagmus patterns appear to depend in considerable part on learned responses originating in the gray matter of the brain.

Caloric Tests