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Biomedical subjects

A Katsarkas

Publications and source records attributed to A Katsarkas.

At least 37 records · Page 2Linked to original sources
PubMed1989

Sudden unilateral sensorineural hearing loss: a syndrome or a symptom?

In 122 patients with sudden unilateral sensorineural hearing loss, no apparent cause was identified in 88 cases. In these idiopathic cases, gender did not affect the age distribution and age did not affect the range of most affected frequencies or the severity of hearing loss. Vertigo at onset of the disease was not a sign of poor prognosis. Cases in the idiopathic group could, generally, be distinguished into two groups: (1) cases with hearing loss affecting all (with one exception) or mainly the high frequencies and symptomatology reminiscent of known types of cranial (poly)neuritis; (2) cases with hearing loss affecting mainly the low frequencies and symptomatology reminiscent of Ménière's disease. These data suggest that there may be certain pathophysiologic similarities in these cases with: (a) cranial (poly)neuritis if all or mainly the high frequencies are affected; (b) Ménière's disease if the low frequencies are mainly affected.

Adult↗
PubMed1989

Paroxysmal positional vertigo in the elderly.

In a retrospective study of 806 patients 70 years of age or older complaining of dizziness, 328/806 (40.7%) patients gave a history strongly suggestive of paroxysmal positional vertigo. This prevalence was higher than in other age groups of 7,269 patients seen in our Dizziness Clinic (33.7% in patients 50 years of age or younger; 26.6% in patients 40 years of age or younger). In 158/328 patients, the paroxysm was elicited and nystagmus occurred; in 135/158 patients, the observed nystagmus, during the paroxysm, was identified and in 131/135 patients, it was of the type described by Barany. It is concluded that: (a) the prevalence of paroxysmal positional vertigo increases with advancing age; (b) the usually observed nystagmus, during the paroxysm, in the elderly is of the type described by Barany, and similar to the nystagmus observed in other age groups.

Aged↗
PubMed1988

Goal-directed vestibulo-ocular function in man: gaze stabilization by slow-phase and saccadic eye movements.

Vestibular function was examined during passive head movements having profiles that approximated low-to-intermediate range of natural self-generated movements (10-220 degrees/s peak velocity, about 0.5 s duration). A seated subject looked at a point target on the wall, the lights were extinguished and the chair was briefly turned while the subject tried to "look" at the just-viewed point. The chair was stopped, the lights were turned on again and the target was re-fixated, if necessary. Ocular stabilization was characterized (1) by "net stabilization" that was due to the combined effects of both slow-phase and rapid (saccadic or quick-phase) eye movements, (2) by "cumulative-slow-phase stabilization" that was due to slow-phase eye movements, and (3) by "cumulative-saccadic stabilization" that was due to effects of all rapid eye movements. It was found that both slow-phase and saccadic eye movements tended to keep the eyes on the actual unseen target. During repeatedly applied head movements, net and cumulative-slow-phase stabilization tended to be almost perfect. However, the average magnitude of the error in net stabilization (i.e., deviation from perfection) was always less than the corresponding error in slow-phase stabilization. This occurred because in a given turn, saccadic movements tended to supplement deficient slow-phase movements and to decrement excessive slow-phases. In 4 of 5 subjects, cumulative-saccadic stabilization tended to equal the error in cumulative-slow-phase stabilization. All results were unaffected by head velocities up to +/- 220 degrees/s. It was concluded that these saccades tended to stabilize gaze (eye + head) in space during head movements in total darkness.

Eye Movements↗
PubMed1988

Unilateral loss of peripheral vestibular function in patients: degree of compensation and factors causing decompensation.

Unilateral surgical ablation of peripheral vestibular function has been suggested for the treatment of a number of diseases that involve vestibular dysfunction. The postoperative distressing symptoms usually subside with time, whereupon the patient is said to have clinically compensated. However, even in well-compensated patients, the initial symptoms may reappear--under certain conditions that are briefly discussed (decompensation)--and, in addition, vestibular gaze stabilization deficits, (apparently permanent) appear whenever moderately rapid head movements are imposed. Thus, surgical ablation of unilateral peripheral vestibular function should not be considered "a treatment of choice," and should be performed in only carefully selected cases.

Animals↗
PubMed1986

Hearing loss due to aging (presbycusis).

Presbycusis is the progressive hearing loss caused by histologic changes due to aging. Schuknecht described four histopathologic types of presbycusis and correlated these findings to audiometric data. In a retrospective study, some strict criteria were set to distinguish the "pure" cases of presbycusis in a group of 1,181 subjects, 50 years of age and older, seen in our Audiology Clinic over one year; 91 subjects were found to meet these criteria. An attempt was made to fit the pure tone threshold curves into the types described by Schuknecht and correlate these curves to speech discrimination, tone decay, recruitment, age and sex of these subjects. It was found that: (a) only 50% of these audiograms could be fitted into the described histopathologic types, suggesting that in 50% of the subjects, presbycusis was caused by more than one degenerative process; (b) in 86% of subjects, speech discrimination was excellent or good in quiet; this test therefore may not reflect the difficulties presbycusis have in understanding speech under adverse auditory conditions; (c) subjects with flat pure tone threshold curves had generally good discrimination; (d) no differences were found between males and females; and (e) tests for tone decay and recruitment showed that in most cases the hearing loss was due to cochlear pathology, but these data do not exclude the possibility of central auditory involvement.

Age Factors↗
PubMed1984

Bechterew's phenomenon in humans. A new explanation.

Bechterew's phenomenon, or reversal of post-unilateral labyrinthectomy spontaneous nystagmus following subsequent contralateral labyrinthectomy in experimental animals, has been known for 100 years. However, it is rarely observed in humans. This paper describes Bechterew's phenomenon in a patient following successful mitral valve replacement and aorto-coronary bypass. The observations are compatible with a recent study which postulates that intervestibular commissural pathways, forming closed loops for neural signals between the vestibular nuclei, may be the main site for vestibular compensation which is associated with the recovery of balanced resting activity in the bilateral vestibular nuclei (Galiana 'et al., 1983). Using simple analytic arguments, it is found that compensation of nystagmus following unilateral labyrinthectomy, the Bechterew's phenomenon and its compensation, and recovery nystagmus could all result from long-term neural changes at the level of commissural connections.

Adult↗
PubMed1982

Failure of suppression of post-caloric nystagmus by fixation.

One hundred and seven patients who had failure of fixation suppression (FFS) of their post-caloric nystagmus were studied. Most of them had other ocular motor abnormalities such as defective pursuit, gaze paretic and rebound nystagmus, and saccadic dysmetria. The presence of FFS was unrelated to the type of post-caloric response. The data from this study are compatible with the idea that FFS is a manifestation of a disturbance in the visual-vestibular interaction. While FFS alone is not a useful localizing sign, its presence is patients who are not taking drugs should lead to a search for neurological disease particularly in the posterior fossa.

Brain Diseases↗
PubMed1982

Positional nystagmus of the "central type" as an early sign of multiple sclerosis.

Three young, female adults complained of dizziness and nausea aggravated on lying in supine position. On examination the prominent clinical feature was positional nystagmus of the "central type". All patients finally proved to suffer from multiple sclerosis. Positional nystagmus of the "central type" has been described in patients with pathology in the area of the IV ventricle and in monkeys with experimental lesions of the vestibular nuclei. It has also been described in humans and experimental animals after ingestion of alcohol. It is concluded that presence of this type of nystagmus is a sign of pathology probably localized in the area of the vestibular nuclei. Obviously, multiple sclerosis will be one of the disease processes to be considered. However, ingestion of alcohol a few hours before examination must always be excluded.

Adult↗
PubMed1981

Vestibular and oculomotor disturbances in pathology of the fourth ventricle.

Positional nystagmus of the central type and gaze paretic (gaze evoked) nystagmus have been reported in pathology of the posterior fossa. It has also been reported that positional nystagmus of the central type is only infrequently accompanied by vertigo and nausea. In this paper five cases are discussed which showed positional nystagmus of the central type and/or gaze paretic nystagmus. All cases showed severe vertigo, nausea and vomiting in the provocative head position. In four out of five cases the pathology was found to be in the area of the IVth ventricle. On the basis of recent neurophysiologic data an attempt is made to explain the manifestations of this pathology. It is concluded that positional nystagmus of the central type is presumably due to pathology of the IVth ventricle area. Also, that this type of nystagmus may be accompanied by severe vertigo, nausea and vomiting.

Adult↗
PubMed1979

Oculomotor abnormalities in Friedreich's ataxia.

A clinical neuro-ophthalmological and electro-oculographic study was made on fourteen patients with Friedreich's ataxia. None had evidence of optic nerve dysfunction. No patient complained of oscillopsia although all had ocular motor deficits of varying degrees, which appeared to be related to the severity of the general manifestations of the disease. The defects comprised square wave jerks, jerky pursuit with inability to maintain eccentric gaze resulting in gaze paretic nystagmus and rebound nystagmus. There was failure to suppress by fixation the vestibulo-ocular reflex. The slow phase velocity of caloric nystagmus was always of reduced velocity. There was inability to augment the slow phase velocity of optokinetic nystagmus with increasing stimulus velocity. Abnormalities of the saccadic system were manifest particularly as hypermetria. These signs in combination are suggestive of disease involving the cerebellar flocculus and vermis or their brain stem connections. No abnormalities were found in 17 parents or siblings.

Adolescent↗
PubMed1979

The Nakasuk Project- the conservative treatment of chronic otitis media in Inuit elementary school children.

Modalities of local medical treatment of chronic otitis media in Inuit elementary school children were evaluated over a period of three and a half years in a project associated with the provision of amplification (hearing aids) for students who had significant conductive hearing deficits which interfered with their ability to communicate. The significant medical and educational benefits derived are reviewed.

Acetates↗
PubMed1978

Paroxysmal positional vertigo--a study of 255 cases.

The clinical and electronystagmographic findings of 255 patients with paroxysmal positional vertigo are presented. We believe the disorder should be diagnosed on the basis of the history and clinical findings since we did not find any characteristic electronystagmographic findings other than the recording of an actual attack. Our observations lead us to believe that there is only one type of attack. We conclude that the nystagmus which occurs during the attack is generated by stimulation of the posterior semicircular canal of the lowermost ear.

Adult↗
PubMed1977

An electrooculographic study of internuclear ophthalmoplegia.

The eye movements of 25 patients with internuclear ophthalmoplegia were recorded by electrooculography. The velocity of adducting saccades was markedly less than normal. The velocity of abducting saccades was within the normal range, but statistically there was a wider distribution. Recordings were made in 2 patients several months after the onset of internuclear ophthalmoplegia, at which time the adducting eye velocity was greater than the abducting eye velocity. A patient with a unilateral medial fasciculus lesion showed marked overshoot of the abducting eye on contralateral saccades and overshoot of both eyes toward the side of the lesion. Optokinetic and postcaloric nystagmus were recorded, and the slow phase showed increasing velocity exponential waveform for the abducting eye. The recordings also showed decreasing velocity exponential waveform for the abducting eye. Downbeat nystagmus was as common as upbeat nystagmus in our patients. The findings appear to confirm the theoretical analysis of the eye movement disorder in internuclear ophthalmoplegia provided by Pola and Robinson as modified by recent experimental work in primates.

Brain Ischemia↗
PubMed1976

Cochlear and vestibular dysfunction resulting from physical exertion or environmental pressure changes.

Inner ear damage due to physical exertion or environmental pressure changes has been described only recently. According to Goodhill there are two possible mechanisms of injury: the explosive and the implosive. The former is triggered by increased C.S.F. pressure transmitted to the perilymph space; the latter by increased pressure in the middle ear transmitted to the perilymph space through the two windows. Sudden hearing loss or dizziness, or both, are the main symptoms. The diagnosis will be established by the history, the audiogram, and the electronystagmogram (ENG). The treatment is still controversial. As the formation of a fistula is a real possibility, an exploratory tympanotomy is suggestive on suspected cases. Due to the variety of symptoms every case has to be assessed individually. A detailed history is of utmost importance.

Adolescent↗
PubMed1976

Electronystagmographic findings in cerebellar dysfunction.

Ocular dysmetria is seldom mentioned in the neurootologic literature as an electronystagmographic (ENG) abnormality. For the last two years, we found ocular dysmetria on 38 cases out of 1,879 ENG recordings. Cerebellar dysfunction was the most apparent cause in 13 out of 21 cases examined by us. The group of unilateral hypermetria showed some other ENG abnormalities like positional nystagmus, post-caloric directional preponderance, failure of fixation suppression of post-caloric nystagmus (FFS), more scattered distribution of quick phase amplitudes of post-caloric and optokinetic nystagmus on the side of hypermetria. We wonder whether this symptomatology, or at least part of it, is due to dysfunction of the flocculo-nodular lobe of the cerrebellum.

Aged↗