The nystagmus responses of normal subjects to air and water caloric irrigations of comparable temperatures were compared. Irrigations of 0° air for 60 sec were found to produce nystagmus responses equal in amplitude, frequency and eye‐speed to those evoked by irrigations of 5 cc of ice water. Ice water produced significantly longer responses than did 0° air (mean difference = 11.6 sec). Responses to bithermal air stimuli of 24° C and 50° C were compared to those produced by 30°C and 44° C water. No significant differences were found between the cool stimuli for any of the measures. The warm stimuli produced responses of equal eye‐speed, but the water responses were significantly greater than those of air when the measures of total amplitude, frequency and duration were compared; thus, air stimulation was the preferred method of performing the standard caloric test, since the air responses were equal in reliability to those of water and because of the advantages of the use of air, which include greater convenience, patient tolerance, applicability, and flexibility.
An audiologic study of 290 hemodialysis and renal transplant patients revealed that in 43 of these patients significant hearing loss developed which could be directly attributed to the therapy of the kidney problem. The clinicopathologic findings in 16 temporal bones of eight chronic hemodialysis and renal transplant patients were presented. The five patients treated with 59 or less hemodialyses had no subjective hearing loss; on the other hand, the three patients receiving 264 or more hemodialyses and multiple transplants, complained of hearing and vestibular difficulties. The pathologic findings common to all 14 temporal bones of the seven patients who underwent transplantation were blue stained concretions in the stria vascularis and/or vestibular receptors. The cochlear changes noted ranged from mild loss of outer hair cells and spiral ganglion cells in patients with few hemodialyses and transplants to complete absence of the organ of Corti in patients receiving more than 264 hemodialyses and multiple transplants; thus, the severity of the clinical and histopathological temporal bone findings was directly proportional to the number of hemodialyses and transplants to which the patient had been subjected. This seems to suggest that numerous hemodialyses or recurrent kidney transplants can induce electrolytic, osmotic, biochemical, vascular and/or immunological changes in the inner ear which can lead to severe audioves‐tibular symptoms and pathology.
The role of the eye movement response in the production of vestibular habituation was studied. One group of cats was subjected to an habituation series of 15 unilateral caloric irrigations while paralyzed with gallamine triethiodide. A second group of cats underwent an identical habituation procedure but was not paralyzed. Tests conducted following recovery from paralysis showed that the responses of the previously paralyzed cats were habituated and did not differ from the responses of animals habituated in a normal manner. These data are interpreted as supporting a central origin for the phenomenon of vestibular habituation.
The influence of various forms of visual stimulation presented during the course of vestibular habituation to a caloric stimulus was studied. Eye movements which were either complementary or in opposition to the induced vestibular nystagmus were produced with an optokinetic drum. In addition, the effect of visual fixation during vestibular-response periods was studied. In all cases, the cats that received visual stimulation during the majority of the caloric trials habituated more slowly than did animals that received all the habituation trials in total darkness. These data conflict with previous reports of vestibular-visual interactions. Possible explanations for the discrepancy include species differences, distraction provided by the visual stimuli, and the transfer of learning from the dark to light conditions.
This study represents an analysis of 450 mediastinoscopies performed at the University of Minnesota Hospitals between July, 1964, and February, 1972. The complication rate was 1.8 percent and there was no mortality. The overall positive biopsy rate was 44.0 percent with 93 benign and 105 malignant diagnoses made by mediastinoscopy. The yield of mediastinoscopy in bronchogenic carcinoma was significantly better than that of bronchoscopy, cytology and scalene node biopsy. At 19 thoracotomies in patients with positive mediastinoscopy the lesions were found to be unresectable. Contraindications to mediastinoscopy are few, the only absolute one being a previous mediastinoscopy. Mediastinoscopy is indicated in all cases of bronchogenic carcinoma to determine resectability. Mediastinoscopy is the procedure of choice for the diagnosis of sarcoidosis.
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