Failure Of Fixation Suppression Research Articles

Rotational and Collic Vestibular-Evoked Myogenic Potential Testing in Normal Developing Children and Children With Combined Attention Deficit/Hyperactivity Disorder.

Vestibular dysfunction in childhood can have a major effect on a child's developmental process. Balance function has been reported to be poorer in children with attention deficit and hyperactivity disorder (ADHD) than in their typically developing peers. Due to contradictory available evidence and the paucity of research on vestibular function specifically in children with combined ADHD (cADHD), we designed this aged-matched study to assess vestibular function in children with cADHD. We enrolled 30 typically developing children (15 boys and 15 girls; mean age, 9 years 6 months; range, 7 to 12 years) and 33 children (19 boys and 14 girls; mean age, 9 years 0 months; range, 7 to 12 years) with cADHD diagnosed by our research psychiatrist. Typically developing controls were used to obtain normative data on vestibular testing and to examine the impact of age on the vestibular response parameters, and these results were compared with those of the cADHD group. All children underwent the sinusoidal harmonic acceleration subtype of the rotary chair test (0.01, 0.02, 0.08, 0.16, and 0.32 Hz) and the cervical vestibular-evoked myogenic potential (cVEMP) test. At all five frequencies in the sinusoidal harmonic acceleration test, there was no significant correlation between age and any of the following rotary chair response parameters in typically developing children: vestibulo-ocular reflex (VOR) gain, phase, asymmetry, and fixation index. Furthermore, there was no significant correlation between age and any of the following cVEMP parameters for the right and left ears of control group: p1 and n1 latency, amplitude, threshold, and amplitude ratio. Significantly higher VOR gains were observed for children with cADHD at frequencies of 0.01 (p = 0.001), 0.08 (p < 0.001), 0.16 (p = 0.001), and 0.32 (p = 0.003) Hz, when compared with the control group. Furthermore, fixation abilities were significantly lower in the cADHD group than in the control group at 0.16 (p < 0.001) and 0.32 (p < 0.001) Hz. cVEMP parameters showed no significant differences between the two groups. Our results showed higher VOR gains and poorer fixation abilities in children with cADHD compared with typically developing children. Cerebellar dysfunction in patients with ADHD has been well documented in the literature, and our findings of cVEMP and rotary chair tests for these children showed impaired vestibular function in these children, based on increased VOR gain values and decreased fixation capabilities. Because VOR gain is mediated through the inferior olive and controlled by the cerebellum, our results suggest that central inhibition of vestibular function may be deficient in children with cADHD, resulting in higher VOR gains. Also, there is general agreement that failure of fixation suppression indicates a central lesion. The lesion can originate from the parietal-occipital cortex, the pons, or the cerebellum. However, failure of fixation suppression is most prominent in lesions involving the midline cerebellum that could be counted for children with cADHD. We believe that this contribution is theoretically and practically relevant as high VOR gains and decreased suppression capabilities may result in symptoms of reading and writing difficulties, learning disabilities, vertigo, and motion sickness in these children. Therefore, assessment of vestibular function in children with cADHD at a young age must be considered when developing rehabilitation protocols for these children.

Auditory and vestibular findings in patients with vestibular migraine

AbstractObjective: We aimed to report audiological and vestibular test results in patients with vestibular migraine (VM). We used a retrospective analysis study design in the setting of a tertiary referral neuro-otology center. Patients and methods: Data from 55 patients with the diagnosis of vestibular migraine were enrolled into the study. Comprehensive audiometry, electronystagmography (ENG) and vestibular myogenic evoked potentials (VEMP) were the interventions and main outcome measures were the degree and profile of hearing loss, speech discrimination, oculomotor gaze, saccades and pursuit abnormalities, as well as the presence of spontaneous, post head-shake and positional nystagmus. We also measured the caloric response peak slow phase velocity, asymmetry, failure of fixation suppression, and VEMP p12-n23 latency response. Results: Sensorineural hearing loss was present in 71% (39/55) of patients; 53% (29/55) had bilateral symmetrical loss, 9% (5/55) had bilateral asymmetrical loss and 9% (5/55) ha...

脊髄小脳変性症の神経耳科学的検討 （第二報） 自律神経検査からの検討

The Schellong test and ECG R-R interval test were performed along with other otoneurological examinations in 33 patients with spinocerebellar degeneration and five with Shy-Drager syndrome.Of the 33 patients 21 (63.3 %) had a positive Schellong test, 8 (44.4%) a positive static R-R interval test and 15 (83.3%) a positive dynamic R-R interval test. In our series abnormalities were observed in patients not only with OPCA, which is supposed to have a pathological relationship to Shy-Drager syndrome, but also in those with LCCA or miscellaneous type. There was a higher incidence of blood pressure and heart rate dysautonomia than difficulty in micturition. Patients with Shy-Drager syndrome had severe dysautonomia in each evaluation.There was no significant relationship between the results of dysautonomia and smooth pursuit and FFS (failure of fixation suppression) which showed great variations of degeneration of neural systems in each case. Only a few patients with dysautonomia complained of dizziness and black-out sensation. This is supposed to be one of the characteristics differences from Shy-Drager syndrome.The Schellong test and the computer-analyzed ECG R-R interval test are of great importance in evaluating the clinical features.

頭頸部外傷例の神経耳科学的特徴について

Neuro-otological studies were made in 84 patients with vertigo or dizziness after head and neck injuries. Patients were classified as traumatic cervical syndrome, simple head injuries, and head injuries with brain stem disorder according to suspected localization.In patients having head injuries with brain stem lesions, equilibrium examination showed the central nervous system disorders, such as gaze-directional gaze nystagmus, failure of fixation suppression, ataxic or saccadic pursuit, diminution of OKN, and abnormal VVOR gain. Nystagmus provocated by neck torsion was frequently observed in patients with traumatic cervical syndrome. So abnormal results in neuro-otological examinations well reflected the condition of the patients with vertigo or dizziness after head and neck injuries. According to our follow-up studies on patients having head injuries with suspected brain stem disorders, there were dizziness and disequilibrium persisted with poor prognosis. However, in the other patients without brain stem disorder the results of equilibrium examinations improved generally.

Computer analysis of fixation-suppression of caloric nystagmus.

Effects of the ocular fixation upon caloric nystagmus were quantitatively analyzed and compared between normal subjects and patients by using a PDP 11/40 computer. The slow-phase velocity was the best parameter to separate normal from abnormal visual fixation. An analysis of caloric nystagmus with failure of fixation-suppression (FFS) made it possible to classify patterns of FFS into three types. The combination of FFS with impairment of the optokinetic responses provides a useful diagnostic tool with respect to lesions located between the brain stem and the cerebellum.

Fixation-suppression of caloric nystagmus in normal subjects

Effects of ocular fixation upon caloric nystagmus have been used as a routine test. Percentage reduction in slow-phase velocity of caloric nystagmus induced by ocular fixation, however, varies depending upon the test condition employed.In the present experiment, we standardized the effects of ocular fixation upon caloric nystagmus in 58 normal individuals. The electronystagmographic test was performed in total darkness. The caloric stimulus was 50ml water, most often 30°C or 44°C, sometimes 20°C, for an irrigation period of 20 sec, with about 7-minute intervals. Subjects were requested to fix their gaze upon a spot on the ceiling about 3m away during the maximum intensity of slow-phase velocity for 10 sec. The amount of reduction of slow-phase velocity induced by ocular fixation was obtained during the first half of the 10-sec period and compared with the control period. The percentage reduction in slow-phase velocity induced by ocular fixation did not depend upon the temperature of the water applied as a caloric stimulus. The mean percentage reduction in slow-phase velocity induced was about 82±12%. On the basis of these results, fixation-suppression of caloric nystagmus was studied in 669 consecutive cases. An analysis of caloric nystagmus with failure of fixation-suppression (FFS) made it possible to classify patterns of FFS into three types. Together with the recent anatomical and physiological data, the underlying neuroanatomical substrates responsible for the FFS was discussed.

Caloric Pattern Test with Special Reference to Failure of Fixation-Suppression

Fixation-suppression of caloric nystagmus was studied in 1230 consecutive cases. An analysis of caloric nystagmus with failure of fixation-suppression (FFS) made it possible to classify patterns of FFS into three types: Type I: FFS was observed bilaterally in caloric nystagmus; Type II: FFS was recognized unilaterally on either side; Type III: FFS was seen in either direction of nystagmus. On the basis of these three types, the underlying neuroanatomical substrate responsible for FFS is discussed.