Complaints of vertigo from people who are exposed to industrial solvents have focused interest on their toxic effect on the nervous system. In order to evaluate the influence of an organic solvent, xylene, on the mammalian vestibular system, a series of rabbit experiments were performed. To achieve a constant concentration, the xylene was infused as a lipid emulsion. Blood concentrations were estimated by gas chromatography. Elec-tronystagmography in darkness revealed that at blood xylene concentrations of 30 ppm all rabbits had a positional nystagmus. The beat direction was the opposite of positional alcohol nystagmus. Another difference between the alcohol and the xylene reaction was that rotatory nystagmus responses were exaggerated. The relations between the present findings and the reactions and blood concentrations in people exposed to industrial solvents are discussed.
Purpose To investigate whether the tickling inside the nose before a light-induced sneeze in susceptible individuals is correlated to a recordable local activity or not. Methods Seven healthy volunteers, three with a history of light-induced sneezing, were stimulated with stroboscopic light or a strong halogen lamp. Recording was done with an evoked potential averaging technique via intranasal electrodes placed in such a way that they substantially reduced the strong electrical response from the retina. Results Despite an adequate light stimulus, no reproducible electrical activity could be recorded from any of the members in any experiment. Conclusion Light-induced sneezing is presumably a central phenomenon. The electrical activity travels through the optic pathways straight to the trigeminal nucleus and the tickling is a referred sensation. A genetic variation in the distance between the optic pathways (colliculus superior) and the mesencephalic part of the trigeminal nucleus may explain why light-induced sneezing is more common in certain families and races.
Experiments in cats have shown that sneezing can be induced using low intensity electrical current. This study focusses on answering the question whether the sneezing-reflex can also be induced in man through electrical stimulation, whether it is reproducible, and if the response can be abolished pharmacologically? Three healthy males were tested using intranasal stimulation in different parts of the nose using a current from an electric pulse generator. Using currents in the range 2-11 mA, it was possible to induce and reproduce sneezing in the anterior portion of the nose corresponding to the distribution area of the anterior ethmoidal nerve. In one tested subject, local anaesthetics applied to the mucous membranes of the nose abolished the sneezing. Sneeze reflex-reduction may be one way to reduce viral contamination between subjects. Further research could include pharmacological investigations to identify a sneeze-inhibiting substance with small risks for side effects that can be added to common cold nasal sprays.
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The method of broad-frequency-band rotatory testing with results from normal subjects and patients with peripheral uni- and bilateral loss as well as central vestibular disorders are reviewed. The following conclusions are drawn: adequate testing of the vestibulo-ocular reflex including side detection of unilateral loss in light or in darkness can only be done with either random or high-frequency (2.5–3 Hz) sinusoidal stimulation. Measurements of compensatory eye movements at lower frequencies where vestibular and non-vestibular signals interact are of interest for central vestibular diagnosis. A decreased ability to suppress vestibular nystagmus is not an uncommon finding in patients with large acoustic neuromas or pathology in the brainstem or cerebellum.
A broad frequency-band rotatory test has been used to quantify compensatory eye movements in 13 healthy subjects during light and darkness conditions. Eye movements were recorded by EOG. Head movements were recorded either by a potentiometer attached to the chair's axis of rotation or by an angular rate sensor attached to a bite-board. Gain and phase values between eye and head velocity were calculated. A systematic error in the higher frequency range is introduced in the results by assuming head movement equal to chair movement. Different instructions in the dark can alter the gain values at lower frequencies (up to 2 Hz) during sinusoidal stimulation. During pseudorandom stimulation no such differences can be obtained. During all test conditions with the rate sensor the gain values approach unity at about 3 Hz.
Fifty-five patients with a unilateral acoustic neuroma were investigated preoperatively with visual suppression tests during rotatory oscillation and caloric irrigation. During a sinusoidal oscillation, 29% of the patients showed a reduced suppression compared to 9% during pseudo-random oscillation and 11% in the caloric test. In the sinusoidal and caloric tests the majority of the patients with deficient suppression had large or medium-sized tumors. In a few patients with small tumors, pathology was observed in both sinusoidal and randomized tests, presumably as a sign of unconcentration. The study shows that the sinusoidal visual suppression test and to a lesser degree suppression during caloric irrigation are of value for identification of brainstem-cerebellum compression of acoustic neuromas.
15 healthy volunteers were investigated in a vestibulo-oculomotor test battery during toluene exposure. The concentration was comparable to the threshold limit value. The results were compared to an identical air experiment. The intoxication caused an impaired visual suppression during a pseudo-random oscillatory swing test and also an increased saccade speed. Other vestibular-oculomotor parameters were normal. The findings are in accordance with our earlier study on styrene in humans, showing that the visual suppression test and the saccade test are sensitive parameters assessing neurotoxic influences by organic solvents.
Conjunctivitis lignosa, a rare affliction of the conjunctiva, is sometimes associated with other disturbances. We present two children with concurrent conjunctivitis lignosa and ear involvement. In these two cases, there were histopathologically verified ligneous changes of the middle ears. Routine haematoxylin and eosin, van Gieson, periodic acid-Schiff (PAS) and alcian blue staining of specimens from the eyes and middle ears revealed findings typical for ligneous conjunctivitis. In addition, new histochemical and immunohistochemical studies for glycosaminoglycans on specimens from the eyes and middle ears showed that the accumulations of the amorphous, cell-deficient material stained strongly but heterogeneously for hyaluronic acid and weakly but uniformly for keratin sulphate. The staining for other glycosaminoglycans, e.g. chondroitin-4-sulphate and dermatan sulphate was confined to vessels and areas rich in collagen fibres and fibroblasts. In patients with conjunctivitis lignosa, the ear involvement may remain undiagnosed due to its resemblance to secretory otitis media with effusion. Since isolated ear involvement may occur, we advocate biopsies for routine haematoxylin and eosin, and specific staining for hyaluronic acid and keratin sulphate, also in children with protracted, refractory otitis media with atypical effusion.
Conclusion. Among 20 patients with inner ear complications and/or peripheral facial palsy secondary to acute otitis media (AOM) a proven or probable bacteriological cause was found in 13 (65%). In seven patients (35%), a proven or probable viral cause was found. Only two of the patients (10%), with a proven bacterial AOM and a clinical picture of a purulent labyrinthitis in both, together with a facial palsy in one, had a substantial degree of dysfunction. Although the number of patients in this study is relatively low our findings show that inner ear complications and facial palsy due to AOM can be of both bacterial and viral origin. Severe sequelae were found only where a bacterial origin was proven. Objectives. Inner ear complications and/or peripheral facial palsy secondary to AOM are rare. The general understanding is that they are due to bacterial infections. However, in some of these patients there are no clinical or laboratory signs of bacterial infections and they have negative bacterial cultures. During recent years different viruses have been isolated from the middle ear or serologically proven in AOM patients and are thought to play a pathogenetic role. We suggest that in some cases of AOM complications from the inner ear and the facial nerve can be caused by viruses. The purpose of our study was to analyze infectious agents present in patients with inner ear complications and/or facial palsy arising from AOM. Patients and methods. The medical records of 20 patients who had inner ear complications and/or facial palsy following AOM (unilateral in 18, bilateral in 2) between January 1989 and March 2003 were evaluated. Bacterial cultures were carried out for all patients. Sera from 12 of the patients were stored and tested for a battery of specific viral antibodies. In three patients, investigated between November 2002 and March 2003, viral cultures were also performed on samples from the middle ear and nasopharynx. Results. Nineteen patients had inner ear symptoms. Eight of them had a unilateral sensorineural hearing loss and vertigo, three had vertigo as an isolated symptom and one, with bilateral AOM, had bilateral sensorineural hearing loss. Seven patients had a combination of facial palsy and inner ear symptoms (unilateral sensorineural hearing loss in three, unilateral sensorineural hearing loss and vertigo in two, bilateral sensorineural hearing loss and vertigo in one, with bilateral AOM, and vertigo alone in one). One patient had an isolated facial palsy. Healing was complete in 11 of the 20 patients. In seven patients a minor defect remained at follow-up (a sensorineural hearing loss at higher frequencies in all). Only two patients had obvious defects (a pronounced hearing loss in combination with a moderate to severe facial palsy (House-Brackman grade 4) in one, distinct vestibular symptoms and a total caloric loss in combination with a high-frequency loss in the other. Eight patients had positive bacteriological cultures from middle ear contents: Streptococcus pneumoniae in two, beta-hemolytic Streptococcus group A in two, beta-hemolytic Streptococcus group A together with Staphylococcus aureus in one, Staph. aureus alone in one and coagulase-negative staphylococci (interpreted as pathogens) in two. In the 12 patients with negative cultures, there was a probable bacteriological cause due to the outcome in SR/CRP and leukocyte count in five. In four patients serological testing showed a concomitant viral infection that was interpreted to be the cause (varicella zoster virus in two, herpes simplex virus in one and adenovirus in one.) In three there was a probable viral cause despite negative viral antibody test due to normal outcome in SR/CRP, normal leukocyte count, serous fluid at myringotomy and a relatively short pre-complication antibiotic treatment period. © 2006 Taylor & Francis.
Thirteen normal subjects were investigated with a broad frequency-band (up to 4.5 Hz) rotatory test. The vestibular stimulation consisted of either a pseudo-random or a sinusoidal frequency sweep oscillation. Eye movements were recorded by EOG. Head movements were recorded either by a potentiometer attached to the chairs axis of rotation or by an angular rate sensor attached to a biteboard. Gain and phase values between eye and head movements were calculated. Measurements were performed in light and darkness during the execution of various fixation tasks. In the higher frequency range there was a difference in gain and phase between potentiometer and rate sensor measurements due to movement of the head relative to the headholder. Visual suppression, in agreement with earlier studies, was more effective during a sinusoidal stimulation than during a pseudorandom stimulation at low frequencies, using the more precise rate sensor measurement technique. Different instructions in the dark could alter the gain values at lower frequencies (up to 2 Hz) during sinusoidal stimulation. During pseudo-random stimulation no such differences could be elicited. Under all test conditions with the rate sensor, the gain values approached unity at about 3 Hz.
Ten healthy volunteers were subjected to a vestibulo-oculomotor test battery before, during and 1 hour after trichloroethylene exposure. The concentration of trichloroethylene in in-spiratory air was 32–78 ppm (176429 mg/m3). The concentration of trichloroethylene in venous blood was followed throughout the experiment. The mean pulmonary uptake was estimated. Each test person was also subjected to a control experiment, breathing air free of trichloroethylene. A decreased ability to visually suppress the vestibulo-oculomotor reflex during sinusoidal stimulation was noticed during trichloroethylene exposure. One hour after exposure the test subjects showed a decreased maximum velocity of the voluntary saccade and a decreased ability to follow a sinusoidally moving target.
Objective methods for critically evaluating the toxic effect of industrial solvents are highly desirable. As many of these solvents are suspected to cause vertigo, an animal experimental model was set up for studying the effects of solvents on the vestibular systems. The vestibular function was studied by registration of involuntary eye movements--nystagmus--which are elicited via central vestibulo-oculomotor connections. During exposure to styrene a so-called positional nystagmus was demonstrated that indicated vestibular disturbances. Nystagmus is normally elicited by rotatory acceleration. During exposure to styrene the direction of this rotatory nystagmus was reversed. The incidence of the positional nystagmus correlated well with the blood level of the solvent, measured by gas chromatography. Kinetic studies also demonstrated a rapid equilibration between the level of the solvent in arterial blood and cerebrospinal fluid, and therefore suggested that estimation of the arterial level reliably indicates the level in the central nervous system.
A previously described experimental model for studying the effects on the central nervous system of rabbits, specifically the vestibular apparatus, has been applied to methylchloroform. To achieve a steady concentration the solvent was infused as a lipid emulsion. The blood and cerebrospinal fluid kinetics have been studied. The arterial blood level seems to be closely correlated to the concentration in the central nervous tissue. Vestibular function has been studied by recording the involuntary eye movements — nystagmus — which are elicited via central vestibulo-oculomotor connections. At blood levels of methylchloroform above 75 ppm a so called “positional nystagmus”, indicated vestibular disturbances, is demonstrated. The relationship between the present findings in rabbits and the reaction and blood concentrations in people exposed to industrial solvents, are discussed.
Fifteen patients with disabling Meniere's disease were treated with local intratym-panic administration of gentamicin once daily. They had suffered from frequent attacks of vertigo and vomiting, the hearing in the affected ears was decreased permanently, and spontaneous nystagmus was observed. The number of treatment days ranged between 3 and 11. Follow-up time was 1 to 6 years. For evaluation of the treatment, audiologic and vestibular examinations were used, including the broad frequency-band rotatory test (0.4-4.5 Hz). Fourteen patients were free from vertigo after treatment. In 5 patients, there was an increased hearing loss, and in 10 it remained unchanged. Tinnitus and fullness sensations were diminished. After treatment, all ears were unresponsive to caloric stimulation. The clinical examination and rotatory testing in light with sinusoidal stimulation revealed good central compensation of the vestibular loss. However, with pseudorandomized oscillations in darkness, the broad frequency-band rotatory test quantified the loss of peripheral vestibular function and was able to detect the side of the lesion in eight of nine patients.
Nine subjects with long-term (8-30 years) occupational exposure to industrial solvents and a confirmed diagnosis of psycho-organic syndrome (POS) have been studied with audiological and otoneurological test batteries. The results were compared to a matched control group of nine industrial workers not exposed to solvents and to normal data from healthy volunteers. In the clinical examination, the Romberg test identified 5/9 workers as pathologic and concurrently the stabilometry showed significantly larger sway areas in the POS-group. In the audiological test battery, the significantly pathologic tests were discrimination of interrupted speech and evoked cortical responses to frequency glides (CRA-delta-f). The saccade test disclosed abnormal findings in 5/9 workers. In the smooth pursuit test, abnormality was found at some test frequencies using pseudorandomized stimulus. The VOR-suppression test was significantly abnormal at all test frequencies. The test battery used strongly indicates CNS lesions due to industrial solvents.
Objective: To assess the diagnostic utility of anti-hsp70 antibody screening in sudden deafness. Design: Sera from 27 patients with sudden deafness and 100 healthy blood donors were analyzed by Western blotting (WB) for the presence of antibodies against 68 kD heat shock protein (anti-hsp70). Results: 19% of the patient sera and 14% of the control sera turned out positive, which was not significantly different. Conclusions: The anti-hsp70 WB test lacks clinical utility for diagnostic screening in patients with sudden deafness.