Biomedical subjects
Publications and source records attributed to A M Rubin.
This report describes how a rehabilitation team treats dizziness and vestibular disorders. Team members include a nurse, physician, audiologist, physical therapist, occupational therapist, and a research scientist. Although unusual, this multidisciplinary approach, involving a close-knit group of professionals, is of great benefit in the treatment of vestibular and balance disorders.
Activities of the enzymes choline acetyltransferase (ChAT) and acetylcholinesterase (AChE), which metabolize the neuromuscular transmitter acetylcholine, and malate and lactate dehydrogenase (MDH and LDH), enzymes of oxidative and glycolytic energy metabolism, respectively, were measured in the middle ear muscles of the cat. For comparison, the same enzyme activities were measured in extraocular muscle tissue and in three hindlimb muscles rich in either slow oxidative (soleus), fast glycolytic (white part of vastus lateralis), or fast oxidative glycolytic (plantaris) muscle fibers. ChAT and AChE activities were much higher in middle ear muscles than in hindlimb muscles, consistent with a denser neuromuscular innervation, as in extraocular muscles. By contrast, MDH and LDH activities were remarkably low in the middle ear muscles, lower than in any of the hindlimb muscles or the extraocular muscles. Denervation of the stapedius muscle by peripheral transection of the facial nerve resulted in decreases in all four enzyme activities without associated changes in the tensor tympani. Surgical ablation of the peripheral facial nerve supply to the stapedius muscle appears to be a feasible option for producing its denervation. The results suggest some rather specialized chemical characteristics for the middle ear muscles.
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A case of myasthenia gravis with histopathologic confirmation of spindle cell thymoma and pure red blood cell aplasia is reported. This is the twelfth case in the literature in which a simultaneous occurrence of all three disorders, with documented thymic pathology, is noted. Immunologic observations in this patient include an elevated acetylcholine receptor antibody and antinuclear antibody titer, agglutination of mouse red blood cells when combined with the patient's serum, and lack of inhibition of binding of radioactive erythropoietin to mouse red cell receptors when combined with the patient's serum. Although both myasthenia with thymoma and pure red blood cell aplasia may have a common immunologic denominator, our findings in this case indicate that inhibition of erythropoiesis is unrelated to erythropoietin receptor blockade. An alternative hypothesis is offered based on defective T-cell function.
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We observed acute cerebral blindness and encephalopathy complicating cyclosporin A (CyA) toxicity in a 5-year-old transplantation patient. Serum CyA level was 1,704 ng/ml (normal, less than 300 ng/ml). Additional neurologic complications of CyA toxicity will be reviewed.
A contextual age construct was developed and examined as a transactional, life-position index of aging. The eighteen-item contextual age index included six interrelated dimensions: physical health, interpersonal interaction, mobility, life satisfaction, social activity, and economic security. In addition to the development of the index, associations among contextual age and sociodemographic characteristics were examined for a sample of 640 persons. Chronological age was correlated negatively with mobility and physical health, and positively with economic security, life satisfaction, and interpersonal interaction. Mobility, economic security, life satisfaction, physical health, and interpersonal interaction discriminated between chronological age groups. Interpersonal interaction, economic security, physical health, and social activity were predictors of life satisfaction. The contextual age construct raises questions concerning several negative myths about aging. The findings reflect the weak validity of chronological age as a unidimensional indicator of life-position and well-being.
Of 453 Canadian otolaryngologist, 226 responded to a questionnaire, indicating significant interest in the state of facial plastic and reconstructive surgery. The majority of these otolaryngologists practised in larger cities and one-quarter received foreign training. Half of the respondents had academic affiliations and three-quarters considered themselves general otolaryngologists. Almost all the otolaryngologists believed that cosmetic and reconstructive surgery should form a major part of their specialty, this being unanimous among current residents. A large majority felt there should be more facial plastic surgical training, this both at the residency and fellowship levels, preferably through increased surgical exposure. With respect to sub-certification, only the resident group was in favor.
Mondini's deformity is the second most common malformation seen in congenital genetic deafness. It is characterized by bony and membranous abnormalities of the inner ear, with a wide range of morphological and functional abnormalities. The importance of the Mondini malformation is that the patient is at an increased risk of developing meningitis or bilateral total hearing loss (or both) at an early age. Six cases are presented which illustrate the various sequelae of the Mondini malformation including meningitis, vertigo, and auditory deterioration. Decompression of the endolymphatic sac was undertaken in three patients. Emphasis is placed on the danger of head trauma, even minor, in these patients. The necessity of early diagnosis with adequate patient counseling is stressed.
The decay times of optokinetic afternystagmus (OKAN) and the vestibuloocular reflex (VOR) were measured in six subjects with chronic unilateral labyrinthectomy and in six age-matched controls. Both OKAN and VOR decay times showed parallel reduction following unilateral labyrinthectomy when the induced nystagmus beat toward the side of the lesion. The VOR decay time for nystagmus beating toward the contralateral side was also significantly reduced. Our findings support the view that the optokinetic system increases the vestibular decay time, that separate left and right velocity storage mechanisms do exist, but that the decoupling between the two sides is far from perfect.
This case report illustrates an unusual hazard of underwater sports: vagal neuropathology secondary to early poliomyelitis which resulted in residual palato-pharyngeal paresis. Gag and swallowing reflexes appeared to function adequately but in fact were not normal. When stressed, during water aspiration, they were inadequate, resulting in great risk to the underwater enthusiast. A history of early viral myelitis must be considered as a potential hazard in underwater sports.
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Mycobacterial infections, once relatively rare in North America have recently shown an upsurge with the influx of Asian and African immigrants. The infections are usually due to M. tuberculosis and present with pulmonary symptoms. However, an uncommon presentation is that of a mass in the head and neck region without any pulmonary manifestations. Although these infections are usually secondary to invasion by "atypical" mycobacteria, unusual presentations due to mycobacterium tuberculosis have been noted. Case reports depicting the very rare presentations of M. tuberculosis in the thyroglossal duct cyst, parotid, and submandibular lymph node are described. A very unusual case of atypical mycobacteria in the larynx is noted and cervical adenitis is also included. The initial subtle presentation emphasizes the importance of mycobacteria in the differential diagnosis of lesions in the head and neck region.
1. Responses suggesting activation of the vestibular system, elicited by electrical stimulation of the human thalamus during 22 routine stereotaxic neurosurgical procedures, were examined in a retrospective study to determine the possible existence of vestibulothalamo-cortical projections in man. 2. Such responses were most frequently described as sensations of movement through space and were associated with two distinct vestibulothalamic projections: a) an anterior relay was situated ventral to the medial lemniscus, passing lateral to the red nucleus and dorsal to the subthalamic nucleus prior to terminating in the nucleus ventrointermedius (Vim) (comparable to VPLo in primates); b) a posterior relay associated with the auditory pathway (lateral lemniscus and brachium of the inferior colliculus) projected to the medial geniculate body. 3. The production of sensations of motion in conscious patients by stimulating areas that are similar to those reported constituting vestibulothalamic pathways in cats and primates implies a distinct primary sensory cortical projection for processing information from the vestibular receptors pertaining to the recognition of spatial movements.
The vestibular nuclei of cats were explored extracellulary with micropipettes to locate units with a resting discharge rate which responded to rotation in the horizontal plane. These units were examined for somatosensory input from neck and limbs. Fewer than half responded to somatosensory stimulation. The neck region was the body area most effective in influencing unitary activity. The response pattern most often noted was an increase and decrease in discharge frequency when the body was moved towards and away from the recording electrode respectively. Change in discharge rate was observed to be primarily dependant upon neck velocity and not upon absolute neck position. Half of the somatosensory units received input from either the forelimbs or the hindlimbs, while the remaining half responded to both.
Changes in the ability to discriminate speech from a eucapnic state to hyperventilation and hypercapnia were investigated. Standard speech audiometric techniques were employed to determine the speech reception threshold and the speech discrimination values, while respiratory conditions were varied and measured utilizing a mixed-gas breathing method. Respiratory parameters were similar to those encountered in aircraft personnel who experience oxygen/pressure system malfunction. The results of the study suggest no significant change in the speech reception threshold while in a hyperventilated or hypercapnic state. The speech discrimination results, however, suggest a significant performance decrement while in a state of hyperventilation.
It has been well established that unequal air pressure across the tympanic membrane causes an increase in puretone thresholds. Very little information is available, however, concerning concommitant effects on reception and discrimination of speech material. This study was designed to determine whether or not further detrimental effects upon the communication process might occur in the form of decreased speech discrimination ability. The findings established that a high positive pressure in the external meatus can result in a deterioration of the individual's ability to discriminate speech sounds.