Johan Bergenius

Function of semicircular canals, utricles and saccules in deaf children

Objective To study vestibular function in deaf children. Material and Methods In 36 deaf children the function of the semicircular canals, saccules and utricles was measured by means of caloric testing, recordings of vestibular-evoked myogenic potentials (VEMPs) and measurements of the subjective visual horizontal (SVH) at different body tilts, respectively. Results In total, 30% of subjects had caloric hypo- or areflexia and 24% had a caloric asymmetry. VEMPs were weak or absent bilaterally in 22% of cases, and asymmetric in 19%. Regarding the utricle, 17% of subjects had a pathologically reduced perception of roll tilt to both sides and 25% had an asymmetry. In total, 30% of subjects were pathologic in all 3 tests and 30% were completely normal. Semicircular canal function correlated best with the function of the saccule. If hearing was better than 90 dB (pure-tone average of 0.5, 1.0 and 2.0 kHz) vestibular function was often normal. For hearing levels of 100–120 dB, otolith function declined significantly. Conclusions Vestibular function tends to be preserved up to a point where hearing is nearly extinct. Hearing level correlates more closely with otolith function, especially that of the utricle, than with semicircular canal function.

Vestibular Neuritis: a Follow-up Study

Seven to eight years after a disease period of vestibular neuritis 19 patients previously examined at our department were given a questionnaire about whether they had experienced any audiovestibular symptoms since they first fell ill. All 19 patients responded and 18 consented to participate in the long-term follow-up study. The patients were subjected to a clinical evaluation, a bithermal caloric test and audiological examinations with stapedius reflex measurements with use of the same technique as at the first examinations. Ten of the 18 patients had experienced recurrent vestibular symptoms with sensation of dysequilibrium and vertigo. Six of these 10 patients also had periods of positional vertigo. The remaining nine patients were free of symptoms. None of the patients had noticed any change in their hearing ability. The mean caloric side difference at the 7- or 8-year follow-up was not significantly higher in the group of patients with symptoms than in the group without symptoms. Neither did the group of patients with pathologically elevated stapedius reflex thresholds at onset display a larger mean caloric side difference than the group of patients with normal thresholds. However, a small caloric side difference at onset of the disease served as a predictor for residual vestibular symptoms. It is speculated whether the group of patients with residual symptoms had a different pathophysiological localization of their disease within the vestibular system than the group of patients with no symptoms at follow-up.

Persistent geotropic nystagmus--a different kind of cupular pathology and its localizing signs.

Abstract Conclusion. A persistent geotropic positional nystagmus indicates a dysfunction in the lateral semicircular canal with a cupula of less specific weight than the surrounding endolymph. It is possible to determine the side of the affected cupula by recording the nystagmus pattern in yaw and pitch plane. Objectives. To identify the clinical features in patients with a persistent geotropic positional nystagmus, establish lateralizing signs and relate the findings to a pathophysiologic mechanism. Patients and methods. Six patients with acute onset vertigo of a peripheral origin and persistent geotropic nystagmus were examined with videonystagmoscopy and the nystagmus characteristics in different positions of the head in yaw and pitch plane were studied. Results. Besides the persistent geotropic nystagmus, a zero zone was found with no nystagmus, beyond which the nystagmus changed direction when the head of the patient in supine position was gradually rotated from side to side. The zero zone was present when the head was turned slightly towards one side and is thought to represent a position where the affected cupula is aligned with the gravitational vertical. With the head bent forwards the nystagmus direction was to the non-affected side and when the head was bent backwards to the affected side.

Treatment of Anterior Benign Paroxysmal Positional Vertigo by Canal Plugging: A Case Report

A 75-year-old man with incapacitating anterior canal benign paroxysmal positional vertigo (BPPV) was relieved of symptoms following anterior semicircular canal occlusion using a transmastoid approach. The preoperative symptoms were similar to those of posterior canal BPPV. The preoperative findings on Dix-Hallpikes maneuver were a paroxysmal torsional nystagmus with a down-beating component that increased when the patients gaze was directed towards the affected ear. The most provoking head movement for the vertigo nystagmus was Dix-Hallpikes maneuver with the affected ear lowermost.

Subjective Visual Horizontal During Follow-up After Unilateral Vestibular Deafferentation with Gentamicin

The subjective visual horizontal (SVH) was measured by means of a small, rotatable, luminous line in darkness in the upright head and body position and at 10, 20 and 30 degrees of tilt to the right and left before, and repeatedly during a follow-up period of 1 year after intratympanic gentamicin instillations in 12 patients with recurrent vertigo attacks. This treatment caused a loss of the bithermal caloric responses on the diseased side. Shortly after treatment there was a significant tilt of SVH towards the treated side (group mean = 10.6 degrees). Repeated testing made it possible to characterize mathematically the changes with time for SVH. For the group of patients as a whole this otolithic component of vestibular compensation was best described by a power function, SVH = 8.65t(-0.16) degrees, where t is time in days after maximum tilt of SVH. After 1 year, SVH was still significantly tilted towards the treated side (group mean = 3.16 degrees). Gentamicin treatment also caused a significant reduction in the perception of head and body tilt towards the deafferented side, while the perception of tilt towards the healthy side did not show any significant changes. During follow-up there was a gradual improvement in the perception of tilt towards the treated side. However, a significant asymmetry in roll-tilt perception was still present 1 year after deafferentation. There was no correlation between SVH in the upright position and roll-tilt perception, suggesting that these parameters are to some extent dependent on different afferent input from the vestibular organ. They were also found to be complementary for the detection of vestibular disturbance.

AUDIO-VESTIBULAR FINDINGS IN PATIENTS WITH VESTIBULAR NEURITIS

19 patients with the clinical diagnosis vestibular neuritis, i.e., cases with unilaterally ENG verified abolished or reduced caloric reactions but without symptoms of central nervous involvement or hearing impairment, participated in the study. In addition to ENG examinations and Békésy audiometry all patients were submitted to stapedius reflex tests and auditory brainstem response examinations (ABR) for signs of subclinical auditory nerve engagement. In all but one of the 19 patients the caloric reactions improved; 8 of the 13 patients available for tests after one year recovered completely. The ABR was normal in all cases but the stapedius reflex thresholds were pathologically elevated and remained so in about half of the subjects throughout the observation time; reflex decay was not present in anyone. Cases with pathologically elevated stapedius reflex thresholds showed a tendency to slower recovery of the vestibular function than the group with the normal reflexes. The results were interpreted to indicate lack of eighth nerve or CNS engagement. The possibility that subjects with reflex threshold elevation may constitute a group with constitutional weakness of the audio-vestibular apparatus disposed for vestibular disease is discussed.

Nystagmus Findings in Healthy Subjects Examined with Infrared Videonystagmoscopy

The increased use of videosystems for the detection of nystagmus is a new diagnostic tool in the diagnosis of patients with vestibular disorders. Small video cameras mounted in a light sealed mask visualize the eyes which are illuminated with infrared light. Compared to the well-established use of Frenzel glasses the patient has no visual references at all. This new technique requires standards for normal limits. Thirty subjects between 20 and 78 years of age with no history of vestibular disorders were examined with infrared video-oculoscopy with the gaze in primary position, after head-shake and in supine position with head torsion and Dix-Hallpike positions backward and forward according to a standardized procedure at our department. Two subjects had spontaneous nystagmus, but nystagmus after head-shake was not found in any. No subject had torsional nystagmus in the Dix-Hallpike positions. In the elderly subjects horizontal nystagmus in head hanging position was a frequent finding.

The Subjective Visual Horizontal for Different Body Tilts in the Roll Plane: Characterization of Normal Subjects

In order to establish a method for estimation of the perceptual horizontal as a test of otolith function in diagnosis of atypical vertigo, in a first study we have standardized a test procedure and characterized a body of normal material consisting of 72 healthy subjects, 24 of them examined with tests followed by retests. The perceptual visual horizontal in darkness was estimated in the upright body position and at body tilts of 10, 20, and 30 degrees to the right and to the left by means of a narrow luminous bar. The deviation of the perceptual horizontal relative to the gravitational horizontal is expressed as a function of body tilt. In the upright body position, 95% had a perceptual horizontal within the range of +/- 2.5 degrees. In the tilted positions, there was a tendency to set the light bar tilted oppositely with respect to the body tilt. The results suggest that roll tilt to the right and to the left is sensed by two independent functional units. Furthermore, the results imply that some other factor might be of importance and that the perceptual horizontal in the upright position and tilt perception are complementary in reflecting vestibular function. Differences between individuals were great in comparison with intraindividual variability and the test-retest variability. The results are discussed against the background of the extensive literature.

The Subjective Visual Horizontal after Stapedotomy: Evidence for an Increased Resting Activity in Otolithic Afferents

The subjective visual horizontal (SVH) was measured by means of a small rotatable luminous line in darkness in the upright body position and at 10, 20 and 30 degrees of body tilt to the right and left prior to, and during a follow-up period after, stapedotomy in 12 patients with otosclerosis. In the acute stage after surgery, SVH in the upright body position was significantly tilted away from the operated side. In addition, the perception of roll tilt towards the operated side (Kop) was significantly increased after stapedotomy, while the perception of roll tilt towards the healthy side (Khe) showed a slight but not significant reduction. After exclusion of two outliers, a statistically significant correlation was found between changes in Kop and in Khe. The slope of the regression line was 1.8:1, probably corresponding to a preference of the utricle for ipsilateral as opposed to contralateral head tilt. In four patients there was a weak ( < 1 degrees/s) spontaneous nystagmus, not systematically related to the side of surgery, while in most cases there were no nystagmus or subjective vertigo symptoms. These specific changes in the subjective horizontal show that the otolithic effects on perception can be dissociated from canal effects. Further, the results are opposite to those for patients with unilateral loss of vestibular function. The tilt of SVH after stapedotomy indicates an increase in resting activity of utricular afferents. In addition, based on recent theories on otolith function, we suggest that an increased activity in saccular afferents is of major importance for the changes in roll-tilt perception because of its interaction with the utricle on the central nervous level.

Saccade Abnormalities in Patients with Ocular Flutter

In a group of 8 patients with opsoclonus or ocular flutter, the eye movements were recorded by electro-oculography (EOG). The spontaneous eye movement pattern and the amplitude and peak velocity of the refixation saccade were analysed. The EOG recording demonstrated frequent bursts of horizontally and vertically directed saccades elicited without any intersaccadic interval. Three patients also demonstrated an increased frequency of square waves. In 6 of the 8 patients the peak velocity of the voluntary saccades was increased; in 5 patients this condition was found for saccades in both directions. Over-shooting oscillations or slightly hypermetric voluntary saccades occurred in 5 patients. It is proposed that the ocular flutter and the increased saccadic velocities found in the present series of patients is caused by a disorder of the burst cells in the brain stem saccadic control system.