Head-upright tilt-table testing: a useful tool in the evaluation and management of recurrent vertigo of unknown origin associated with near-syncope or syncope

Recurrent idiopathic vertigo associated with near-syncope and syncope is a common perplexing problem, some cases of which are considered autonomically mediated (vasovagal). Upright-tilt-table testing has emerged as a potential method to test for vasovagal episodes. This study evaluated the use of this technique in the evaluation and management of patients with recurrent idiopathic vertigo associated with near-syncope or syncope. Twenty-one patients with recurrent unexplained vertigo and syncope/near-syncope and 11 control subjects were evaluated by use of an upright-tilt-table test for 30 minutes, with or without a graded isoproterenol infusion (1 to 4 micrograms/min given intravenously), in an attempt to provoke hypotension, bradycardia, or both, which reproduced the patient's symptoms. The patients included 10 men and 11 women (mean age, 51 +/- 16 years). Eleven controls with no history of vertigo were also studied. Transcranial Doppler sonography was used to assess cerebral arteriolar blood flow during tilt. All tilt-positive patients were placed on therapy with either beta-blockers, disopyramide, or transdermal scopolamine, the effectiveness of which was determined with another tilt-table study. Symptoms occurred in seven patients (33%) during the baseline tilt and in eight patients (38%) during isoproterenol infusion (total positives, 71%). Transcranial Doppler sonography demonstrated a 225% +/- 192% increase in pulsatility index and a 70% +/- 29% increase in resistance index (indicative of cerebral arteriolar vasoconstriction) at the time of vertigo. No control subject experienced syncope during this test. Each tilt-positive patient eventually became tilt-negative with therapy, and over a mean follow-up period of 26 months, no further episodes have occurred.(ABSTRACT TRUNCATED AT 250 WORDS)

The team approach to treatment of the dizzy patient

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.

Stabilometry in balance assessment of dizzy and normal subjects

Normal adults and patients referred to the Dizzy Clinic at the Medical College of Ohio had their standing balance assessed during combinations of normal and altered visual and somatosensory orientation conditions using a fixed-force platform to measure center-of-pressure translations. Significant differences were identified between normal subjects and dizzy patients, depending on the particular diagnostic category, the sensory condition tested, and the particular sway component being measured. Patients with central and peripheral vestibular dysfunctions had significantly greater sway than all other categories in most test conditions, especially with eyes closed and with a visual conflict dome while standing on a foam surface. The central vestibular dysfunction and peripheral vestibular dysfunction groups could be differentiated statistically under eyes-closed and visual conflict-foam conditions. The normal and psychogenic groups could not be differentiated statistically for any test conditions except one: there was significantly greater mean anterior/posterior sway displacement in the psychogenic group compared with all other diagnostic categories for the eyes-open foam test condition. Our results indicate that static stabilometry recordings of postural sway can be used to evaluate and quantify a dizzy patient's ability to receive and process vestibular, visual, and somatosensory-proprioceptive cues for postural stability. It can also be used to monitor patients with vestibular disorders and to document their responses to rehabilitation programs.

Enzymes of transmitter and energy metabolism in cat middle ear muscles

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.

Myasthenia gravis with thymoma and pure red blood cell aplasia

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.

Cerebral blindness and encephalopathy with cyclosporin A toxicity

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.

Contextual age as a life-position index

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.

The otolaryngologist's attitude to facial plastic surgery

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.

Contextual age as a life-position index

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.

Mondini dysplasia--late complications

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.

Optokinetic afternystagmus and post rotatory nystagmus in patients with unilateral labyrinthine lesions

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.

Near-drowning, scuba diving: an unusual late sequela of bulbar polio

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.

Parathyroid gland transplantation after total thyroidectomy with pharyngolaryngoesophagectomy

Surgical treatment of extensive hypopharyngeal carcinoma often includes total thyroidectomy together with resection of the primary disease. The risk of removing or damaging the parathyroid glands is considerable; this may render the patient permanently hypoparathyroid with all the problems of management. These patients must be on lifelong supplementation and at times, due to failure to take the medication, hypocalcemic crises are precipitated. To avoid this problem, we have been identifying the parathyroid glands intraoperatively and, after pathological confirmation, have transplanted them to the forearm. Three patients who underwent this procedure are presented. All are normocalcemic without supplementation and parathyroid hormone assays on serum from the transplanted forearm show significantly elevated levels.

Head and neck manifestations of mycobacteria in the absence of pulmonary disease

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.

Limb input to the cat vestibular nuclei

The input from fore- and hindlimbs to the vestibular nuclear complex (VNC) was investigated in awake cats. Electrical stimulus was given to the sciatic, radial and vestibular nerves bilaterally and single unit responses were recorded in the VNC with extracellular technique. The position of the microelectrode was histologically confirmed. All four major vestibular nuclei received fore- as well as hindlimb input. Forty per cent of the neurons with limb input also received vestibular afferents. No major distinguishing features appeared between the different nuclei with regard to response characteristics. Certain differences in laterality of response, quantitative fore-hindlimb ratio and somatosensory-labyrinthine convergence were observed however. Response latencies to sciatic and radial nerve stimuli always exceeded a 3 msec and were grouped around 8 and 16 msec. A third population of vestibular neurons had latencies over 20 msec. Both excitatory and inhibitory responses were recorded, with the latter not always following an activation. The findings illustrate the complex nature of the ascending pathway to the VNC and the integrative properties of this complex.

Labyrinthine and somatosensory convergence upon vestibulospinal neurons

In awake cats cells forming the lateral (LVST) and medial (MVST) vestibulospinal tracts were identified by employing antidromic stimulation of the spinal cord. Neuronal responses to bilateral vestibular, forelimb, hindlimb, and neck electrical nerve stimulation were analysed. Extracellular recording in the vestibular nuclei was performed via a glass micropipette saturated with Fast Green, to aid in later histological tract identification. The number of cells projecting to cervical and lumbar regions in the dorsal and ventral division of Deiters' nucleus did not differ significantly. An unexpectedly large number of MVST units was found in the descending nucleus. Some MVST units projected to the lumbar cord but in both the medial and descending nuclei, projections to the cervical cord were in majority. Almost all spinal projecting vestibular neurons received labyrinthine input and more than half received somatosensory input. The units could be separated into several populations on basis of excitatory and inhibitory labyrinthine response latencies indicating multiple pathways. As regards labyrinthine-somatosensory integration the two tracts were found to be quite similar. The extent and complexity of labyrinthine-somatosensory convergence indicate the importance of feed-back mechanisms upon postural controls also at the level of the vestibular nuclei.

Vestibulothalamic projections in man--a sixth primary sensory pathway

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.

Labyrinthine and somatosensory convergence upon vestibulo-ocular units

The vestibular nuclei were investigated in 18 adult cats. Vestibulo-oculo-motor neurons were identified by antidromic stimulation of the ascending medial longitudinal fasciculus (MLF). The neurons were subjected to various stimuli: vestibular, neck, forelimb and hindlimb nerve stimulation on both sides. The recording was extracellular with micropipettes containing Fast Green. Only the medial and the superior vestibular nuclei were found to project to the MLF. All projecting units had input from the labyrinths. Excitatory response latencies to ipsilateral labyrinth stimulation never exceeded 3 msec. Both excitatory and inhibitory response latencies could be distributed into different categories. The majority of the neurons did not receive a somatosensory input, and surprisingly few convergent units could be seen. Peripheral somatosensory information apparently plays a minor role in vestibulo-ocular relations.

Labyrinthine input to the vestibular nuclei of the awake cat

The labyrinthine input to the vestibular nuclei was investigated in 24 awake cats. Stimulus consisted of electrical shocks given through bipolar silver wire electrodes, implanted in the utricular and lateral ampullar nerves. Throughout the vestibular nuclei, single units were recorded extracellularly with glass micropipettes filled with Fast Green. The tracts of the penetrating electrodes were identified histologically. In all four nuclei units responding to both labyrinths outnumbered unilaterally responding neurones with certain differences between the individual nuclei. Excitatory as well as inhibitory responses were observed, polysynaptic being more common than mono- or disynaptic ones. No monosynaptic contralateral responses were seen. The latency distribution of contralateral responses closely mirrored that of ipsilateral responses within each nucleus. Both excitatory and inhibitory responses fell into relatively segregated populations, based upon latency distribution. This implies separate pathways for labyrinthine input to the vestibular nuclei.

Vestibular and somatosensory interaction in the cat vestibular nuclei

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.

Hearing under stress: II. Effect of hyperventilation and hypercapnia on speech discrimination

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.