Room tilt illusion. A central otolith dysfunction

BACKGROUND: We report a sudden 90 degrees room tilt illusion (RTI) following vestibular stimulation in 3 patients with persistent skew deviation caused by a brain stem lesion. Room tilt illusion is a transient tilt perception of the visual surrounding, on its side or even upside down, that is often reported with brain stem lesions. Although its pathophysiologic cause is not well known, the RTI suggests an impairment of otolith pathways, as reported in skew deviation. METHODS: The 3 patients with brain stem lesions were reexamined as part of a follow-up of patients with signs of otolith dysfunction. A registration of vestibular function was performed with a rotatory chair, including earth-vertical axis rotation for canal stimulation and off-vertical axis rotation (OVAR) for otolith stimulation. Measurement of the subjective visual vertical (SVV) was also performed. RESULTS: The otolith-ocular reflex registered by OVAR was impaired in the 3 patients with skew deviation and the SVV in 2 patients. After each direction of OVAR stimulation, the 3 patients reported an RTI as the room was illuminated. CONCLUSIONS: The coexistence of otolith oculomotor (skew deviation and impaired otolith-ocular reflex) and perceptual (tilt of SVV and RTI) disorders suggests a common otolith dysfunction. However, an RTI occurred specifically after vestibular stimulation and when the room was illuminated. We thus suggest that RTI reflects a dynamic visuo-otolith mismatch.     

Seesaw nystagmus associated with involuntary torsional head oscillations

OBJECTIVE: To assess the diagnostic value of eye-head coupling in seesaw nystagmus (SSN). BACKGROUND: SSN is a rare binocular disorder characterized by alternating skew deviation and conjugate ocular torsion. METHODS: We examined a patient with a congenital nystagmus that switched to a pendular SSN on near viewing and was associated with involuntary torsional head oscillations. RESULTS: The binocular torsional eye movements were in phase with the clinically visible head oscillations (i.e., head movements were not compensatory for the torsional eye movements). CONCLUSION: This finding suggests that torsional eye-head coupling in pendular SSN has a common pathologic origin. We suggest that alternating vertical disparity of both eyes in pendular SSN is compatible with an oscillating signal acting on an intact vestibular system. The absence of brainstem lesions on high-resolution MRI supports this assumption.     

Ocular tilt reaction associated with a sudden idiopathic unilateral peripheral cochleovestibular loss

We recently observed a female patient who was suffering from acute right peripheral cochleovestibular loss associated with a marked vertical diplopia. Otoneurological examination showed profound deafness, and absence of nystagmic response to caloric and pendular rotatory test in the right ear. Neuroophthalmological examination showed skew deviation with right hypotropia, excyclotorsion, and tilt of the static visual vertical directed to the right side. Immunological and serological examinations were normal. Neurological examination and extensive neuroradiological investigations failed to demonstrate any central nervous system involvement. In this patient, skew deviation and tilt of the static visual vertical were interpreted as signs of an acute unilateral otolithic dysfunction, due to a sudden idiopathic peripheral vestibular loss.     

Is visual experience necessary for the maturation of vestibular control of eye movement

The vestibular system contributes to the stabilisation of visual images on the retina by means of vestibulo-ocular compensatory reactions. The development of vestibular control of eye movements has been studied in twelve week old kittens, reared in total darkness, which have been compared with a control group of kittens reared in normal conditions. Post-rotatory nystagmus, nystagmus during sinusoidal oscillations, visual suppression of vestibular nystagmus by fixation, have been used as indicators of the functional state of the vestibulo-ocular control system. The results show that most of the essential features of this control are present in dark-reared kittens. However differences have been noted which possibly concern precise regulation of compensatory movements and head-eye coordination. The frequency of vestibular nystagmus is much smaller in dark-reared animals and the initial deviation of post rotatory nystagmus in the direction of the change of movement is absent in dark-reared kittens. Habituation also seems to operate differently in the two groups of kittens. Visual suppression of vestibular nystagmus is present.     

The caloric vestibular examination: a simplified technique and its normal values (author's transl)

A simple modification of caloric vestibular stimulation and its documentation is described to improve the coordination of vestibular investigation in clinics and practice. A volume of 50 cc. 30 degrees and 44 degrees C water is used to irrigate the ear and is administered within a 10 s period. The patient is then evaluated for the rate and duration of nystagmus, using Frenzel lenses. 1182 patients were investigated in this manner and their results were computerized. It was then shown that irrigation with 30 degrees C water was followed by a greater nystagmus reaction (including vertigo and vegetative signs) than with the 44 degrees water.     

Editorial: A pediatrician''s view

A pattern of eye movement similar to vestibular nystagmus associated with blink is characterized. This artifact can be seen in asymptomatic, otologically normal subjects and is considered to have different meaning than lateral conjugate deviation of the eyes on forced closure of the lids (Cogan sign). Since this nystagmus artifact is most evident during electronystagmographic testing for spontaneous and semispontaneous nystagmus, its importance can be overestimated. Simultaneous monitoring of horizontal and vertical eye movement presently provides a definitive means of identification.     

Reversible malabsorption of folic acid in the elderly with nutritional folate deficiency

The question of the point of impact of the electric current in the galvanic vestibular test is not solved. An important feature is that, after destruction of both the vestibular end organs, a galvanic nystagmus can still be provoked. The effect of a direct current on the spontaneous nystagmus following partial or total destruction of the vestibular end organs was investigated. The frequency of the spontaneous nystagmus diminishes when the electric stimulus causes an eye movement in the same direction as the fast phase of the nystagmus, the frequency increases when the polarity of the electric stimulation is reversed. Simultaneous application of torsion-swing and electric stimulation causes a summation of the separate effects. Our findings confirm the conculsions drawn by Ledoux (4, 5) from his findings in frogs.     

Three-dimensional modeling of static vestibulo-ocular brain stem syndromes

Static vestibulo-ocular brain stem syndromes characterized by skew deviation, a vertical disconjugacy of the eyes, and ocular torsion are the result of a vestibular tone imbalance in the frontal (roll) plane. Similar physiological changes in static eye position, ocular counter-roll and conjugated deviations of vertical eye position, are caused by the influence of gravity mediated by the utricles. These observations prompted our approach with the model described here: based on the known deviations of static eye position, we devised a three-dimensional mathematical model of otolith-ocular function including detailed brain stem anatomy. This model is able to explain and predict the differential effects of unilateral and bilateral peripheral or central vestibular lesions on static eye position in roll, pitch, and yaw planes.     

Deficits in vertical and torsional eye movements after uni- and bilateral muscimol inactivation of the interstitial nucleus of Cajal of the alert monkey

The mesencephalic interstitial nucleus of Cajal (iC) is considered the neural integrator for vertical and torsional eye movements and has also been proposed to be involved in saccade generation. The aim of this study was to elucidate the function of iC in neural integration of different types of eye movements and to distinguish eye movement deficits due to iC impairment from that of the immediately adjacent rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF). We addressed the following questions: (1) According to the neural integrator hypothesis, all eye movements including the saccadic system and the vestibulo-ocular reflex (VOR) share a common neural integrator. Do iC lesions impair gaze-holding function for vertical and torsional eye positions and the torsional and vertical VOR gain to a similar degree? (2) What are the dynamic properties of vertical and torsional eye movements deficits after iC lesions, e.g., the specificity of torsional and vertical nystagmus? (3) Is iC involved in saccade generation? We performed 13 uni- and three bilateral iC inactivations by muscimol microinjections in four alert monkeys. Three-dimensional eye movements were studied under head-stationary conditions during vertical and torsional VOR. Under static conditions, unilateral iC injections evoked a shift of Listing's plane to the contralesional side (up to 20 degrees), which increased (ipsilesional ear down) or decreased (ipsilesional ear up) by additional static vestibular stimulation in the roll plane, i.e., ocular counterroll was preserved. The monkeys showed a spontaneous torsional nystagmus with a profound downbeat component. The fast phases of torsional nystagmus always beat toward the lesion side (ipsilesional). Pronounced gaze-holding deficit for torsional and vertical eye positions (neural integrator failure) was reflected by the reduction of time constants of the exponential decay of the slow phase to 330-370 ms. Whereas the vertical oculomotor range was profoundly decreased (up to 50%) and vertical saccades were reduced in amplitude, saccade velocity remained normal and horizontal eye movements were not affected. Bilateral iC injections reduced the shift of Listing's plane caused by unilateral injections, i.e., back toward the plane of zero torsion. Torsional nystagmus reversed its direction and ceased, whereas vertical nystagmus persisted. In contrast to unilateral injection, there was additional upbeating nystagmus. Time constants of the position integrator of the gaze-holding system did not differ between unilateral and bilateral injections. The range of stable vertical eye positions and saccade amplitude was smaller when compared with unilateral injections, but the main sequence remained normal. Dynamic vestibular stimulation after unilateral iC injections had virtually no effect on torsional and vertical VOR gain and phase at the same time when time constants already indicated severe integrator failure. Torsional VOR elicited a constant slow-phase velocity offset up to 30 degrees toward the contralesional side, i.e., in the opposite direction to spontaneous torsional nystagmus. Likewise, vertical VOR showed a velocity offset in an upward direction, i.e., opposite to the spontaneous downbeat nystagmus. Contralesional torsional and upward vertical quick phases were missing or severely reduced in amplitude but showed normal velocity. In contrast, bilateral iC injections reduced the gain of the torsional and vertical VOR by 50% and caused a phase lead of 10-20 degrees (eye compared with head velocity). We propose that the slow-phase velocity offset during torsional and vertical VOR reflects a vestibular imbalance. It therefore appears likely that the vertical and torsional nystagmus after iC lesions is not only caused by a neural integrator failure but also by a vestibular imbalance. Unilateral iC injections have clearly differential effects on the VOR and the gaze-holding function. (ABSTRACT TRUNCATED)     

A proposal for introducing a modified vestibular index in neurotology. The classification of vestibular neuronitis

The parameters for vestibular dysfunction were modified after our own studies. This index includes the degree of vertigo present, spontaneous nystagmus, dysfunction of the vestibulospinal reflexes and caloric and postrotatory side differences. The index is applicable for defining the extent of a lesion, follow-up, defining its stage and the results of therapy. Introduction of the modified vestibular index is proposed for use in clinical diagnosis. Classification of vestibular neuronitis into groups A, B and C is suggested on the basis of the reversibility of spontaneous nystagmus after caloric stimulation.     

Contribution of vestibular commissural pathways to spatial orientation of the angular vestibuloocular reflex

During nystagmus induced by the angular vestibuloocular reflex (aVOR), the axis of eye velocity tends to align with the direction of gravito-inertial acceleration (GIA), a process we term "spatial orientation of the aVOR." We studied spatial orientation of the aVOR in rhesus and cynomolgus monkeys before and after midline section of the rostral medulla abolished all oculomotor functions related to velocity storage, leaving the direct optokinetic and vestibular pathways intact. Optokinetic afternystagmus and the bias component of off-vertical-axis rotation were lost, and the aVOR time constant was reduced to a value commensurate with the time constants of primary semicircular canal afferents. Spatial orientation of the aVOR, induced either during optokinetic or vestibular stimulation, was also lost. Vertical and roll aVOR time constants could no longer be lengthened in side-down or supine/prone positions, and static and dynamic tilts of the GIA no longer produced cross-coupling from the yaw to pitch and yaw to roll axes. Consequently, the induced nystagmus remained entirely in head coordinates after the lesion, regardless of the direction of the resultant GIA vector. Gains of the aVOR and of optokinetic nystagmus to steps of velocity were unaffected or slightly increased. These results are consistent with a model in which the direct aVOR pathways are organized in semicircular canal coordinates and spatial orientation is restricted to the indirect (velocity storage) pathways.     

Torticollis due to disinhibition of the vestibulo-collic reflex in a patient with Steele-Richardson-Olszewski syndrome

A patient with the clinical picture of Steele-Richardson-Olszewski syndrome and an unusual intermittent neck twisting is reported. He had virtually no voluntary ocular movements and only very slow, low-amplitude voluntary head movements. However, in response to optokinetic or vestibular stimulation, he developed full eye deviations in the direction of the slow phase of the expected nystagmus. No quick phases were observed, and the deviation outlasted the duration of the vestibular stimuli because of defective saccades. The head also turned fully during these stimuli, quicker than on attempted voluntary movements, and remained deviated similarly to the eyes. This suggests that the neck deviations in this patient were due to a disinhibited vestibulo-collic reflex and a disturbed head position resetting mechanism. Neck electromyographic responses in response to whole-body rotation indicated that the vestibulocollic reflex responsible for the torticollis in this patient had a short latency of approximately 30 ms.     

Topical retinoic acid (tretinoin) for photoaging: conceptions and misperceptions

Sinusoidal rotation and rotational stimulation tests were used to examine vestibular function in guinea pigs. The results showed that there was no statistically significant difference in the mean number of nystagmus of semi-cycle sinusoidal rotation test and the duration of nystagmus of rotational stimulation test for both the control and test groups before treatment in albinos and pigmented guinea pigs. Meantime, daily subcutaneous injection of gentamicin 125 mg/kg body weight for 12 days in albinos and pigmented guinea pigs showed no significant change in vestibular function until the 7th day of treatment. Significant impairment of vestibular function was noticed on the 10th treatment day. At 5 days after treatment vestibular impairment reached its maximum and minimal recovery was seen at 14 days after treatment. No Further improvement of vestibular function was noticed three months after treatment. The methods are feasible and reliable.     

Hallucinations, sleep fragmentation, and altered dream phenomena in Parkinson''s disease

Middle ear effusion has been considered the most common cause of vestibular disturbance in children. However, there have been only a few studies on vestibular disturbance in children with otitis media with effusion. We studied the vestibular systems of 30 children with otitis media with effusion aged 8 to 13 years and compared the results with 15 age- and sex-matched controls. A questionnaire relating to vestibular disturbance was given to patients and their parents. Spontaneous nystagmus and positional nystagmus were recorded by electronystagmography as diagnostic tests of the vestibular system. Romberg's and past-pointing tests were performed on children with otitis media with effusion and controls. After vestibular tests were completed, myringotomy was performed, and a ventilation tube was inserted. The questionnaire and the vestibular tests were repeated after the operation and during the first month after surgery. Our study showed that there was a history of vestibular disturbance in 33% of children with otitis media with effusion. Electronystagmography and Romberg's test findings demonstrated that 33% of the children had vestibular dysfunction (p < 0.05). After myringotomy with ventilation tube insertion, vestibular test results returned to normal, and symptoms related to vestibular disturbance improved. These findings confirm the assumption that middle ear effusion may affect the vestibular system, which can be resolved after myringotomy with ventilation tube insertion.     

Presentation and treatment of stapes dislocation and subluxation (author's transl)]

The symptomatology, especially vestibular, and the surgical findings in traumatic dislocation of the stapes into the oval window are described in 2 patients, one of whom seen 1 3/4 h after the accident and the other after 12 days. The main indication for exploratory tympanotomy was change of the spontaneous nystagmus from an irritative to a paretic type. Special attention should be given to positional nystagmus, which increases on turning onto the affected side, the mechanism for which is apparently similar to the positional vertigo of labyrinthine fistulae. Hearing was preserved in both patients. In one patient, vestibular function recovered considerably whilst in the other, there remained considerable impaired function.     

An update on peritoneal dialysis and hemodialysis in the pediatric population

Drugs acting as agonists (SKF38393 and quinpirol) or antagonists (SCH23390 and sulpiride) on dopamine receptors were administered at various doses (1, 2 or 4 mg kg-1 day-1) to aged male rats of the Sprague-Dawley strain subjected to labyrinth unilateral lesion. The time course of vestibular compensation was evaluated by recording spontaneous eye nystagmus and by scoring ambulation and rearing with the open field test and motor ability and coordination with the rotorod test. Treatment started 3 days prior to surgery and continued until day 7 after surgery. The vestibular compensation of untreated young male rats was also studied with the same methods. The decline of spontaneous nystagmus in aged animals was slower than that of young rats and was facilitated by the large doses of quinpirol (D2 receptor agonist) and inhibited by sulpiride (D2 receptor antagonist) 4 mg kg-1 day-1, while the other drugs did not affect this parameter. After operation, ambulation and rearing of aged rats increased more slowly as compared to that of young animals. Moreover, motor performance and coordination in aged rats improved less rapidly than those of young controls. Dopamine receptor agonists increased ambulation and improved motor performance and coordination in aged rats, while dopamine receptor antagonists exerted opposite effects. Rearing was not affected by any kind of drug treatment. These results suggest that dopamine neurotransmission plays a role in vestibular compensation process following unilateral labyrinthectomy in aged animals, and this may have clinical relevance in vestibular pathologies of peripheral origin that are associated to brain ageing.     

Surgical treatment for congenital motive defect nystagmus by the parks (5, 6, 7, 8mm) procedure or the augmented Parks procedure

PURPOSE: The purpose of the surgical treatment for patients with congenital motive detect nystagmus was to correct deviation of the eye and the head tilt, to improve vision and eliminate nystagmus. METHODS: 19 patients underwent the Parks (5, 6, 7, 8mm) or the augmented Parks procedure from 1987 to 1994. For patients with abnormal head turn > or = 30 degrees, We used a 40-60% augmented Parks procedure. RESULTS: A follow up of 19 patients ofr an average of 22 months revealed a marked improvemtnts. After operation, the head turn was decreased form 30.5 degrees to 4.9 degrees, the intensity of nystagmus was decreased from 36.0 to 9.7, 21 eyes (55.3%) of 19 patients improved by two or more lines of Snellen visual acuity. CONCLUSIONS: The Parks (5, 6, 7, 8mm) and the augmented Parks (5, 6, 7, 8mm) procedure produce a marked correction for congenital motive defect nystagmus.     

Vestibular compensation in a patient with a cerebellar infarction

We report the case of a 67-year-old man who suffered a traumatic unilateral peripheral vestibular injury subsequent to an unrelated prior cerebellar infarction that occurred at least 2 years earlier. The patient's clinical course was marked by poor compensation for his peripheral vestibular loss. Four months after his vestibular injury, his symptoms of dizziness had not resolved. He had a spontaneous vestibular nystagmus, and laboratory testing indicated an asymmetric semicircular canal-ocular reflex. The otolith-ocular reflex, tested using off-vertical axis rotation, also was asymmetric but had a preserved modulation component. Visual-vestibular interaction and semicircular canal-otolith interaction were normal. An MRI indicated preservation of the flocculo-nodular lobe but infarction of the pyramis and uvula. Taken together, the findings in this case suggest that despite structural and functional preservation of the flocculo-nodular lobe, an anatomic region often labeled the "vestibulo-cerebellum", a lesion of the cerebellum that can impair CNS compensation for a unilateral peripheral lesion in humans.     

Subjective and physiologic effects of morphine, pentobarbital, and meprobamate

These studies extend previous observations on the effects of pentobarbital on subjective states and postrotational nystagmus in postaddict subjects. Pentobarbital (150 mg) induced a degree of liking and an elevation of the morphine-benzedrine group (MBG) scale score equivalent to 24 mg of morphine. The effects of pentobarbital and meprobamate on postrotational nystagmus were studied using electro-oculography. Both drugs increased the frequency and prolonged the duration of postrotational nystagmus in a dose-related manner. Meprobamate was about 1/15 as potent as pentobarbital in enhancing postrotational nystagmus and producing signs of sedation.