Oscillopsia in Bilateral Vestibular Hypofunction: Not Only Gain But Saccades Too.

OBJECTIVES: Oscillopsia is a disabling condition for patients with bilateral vestibular hypofunction (BVH). When the vestibulo-ocular reflex is bilaterally impaired, its ability to compensate for rapid head movements must be supported by refixation saccades. The objective of this study is to assess the relationship between saccadic strategies and perceived oscillopsia. DESIGN: To avoid the possibility of bias due to remaining vestibular function, we classified patients into two groups according to their gain values in the video head impulse test. One group comprised patients with extremely low gain (0.2 or below) in both sides, and a control group contained BVH patients with gain between 0.2 and 0.6 bilaterally. Binary logistic regression (BLR) was used to determine the variables predicting oscillopsia. RESULTS: Twenty-nine patients were assigned to the extremely low gain group and 23 to the control group. The BLR model revealed the PR score (saccades synchrony measurement) to be the best predictor of oscillopsia. Receiver operating characteristic analysis determined that the most efficient cutoff point for the probabilities saved with the BLR was 0.518, yielding a sensitivity of 86.6% and specificity of 84.2%. CONCLUSIONS: BVH patients with higher PR values (nonsynchronized saccades) were more prone to oscillopsia independent of their gain values. We suggest that the PR score can be considered a useful measurement of compensation.

Relevance of Artifact Removal and Number of Stimuli for Video Head Impulse Test Examination.

OBJECTIVE: To evaluate the effect of artifacts on the impulse and response recordings with the video head impulse test (VHIT) and determine how many stimuli are necessary for obtaining acceptably efficient measurements. METHODS: One hundred fifty patients were examined using VHIT and their registries searched for artifacts. We compared several variations of the dataset. The first variation used only samples without artifacts, the second used all samples (with and without artifacts), and the rest used only samples with each type of artifact. We calculated the relative efficiency (RE) of evaluating an increasingly large number of samples (3 to 19 per side) when compared with the complete sample (20 impulses per side). RESULTS: Overshoot was associated with significantly higher speed (p = 0.005), higher duration (p < 0.001) and lower amplitude of the impulses (p = 0.002), and consequent higher saccades' latency (p = 0.035) and lower amplitude (p = 0.025). Loss of track was associated with lower gain (p = 0.035). Blink was associated with a higher number of saccades (p < 0.001), and wrong way was associated with lower saccade latency (p = 0.012). The coefficient of quartile deviation escalated as the number of artifacts of any type rose, indicating an increment of variability. Overshoot increased the probability of the impulse to lay on the outlier range for gain and peak speed. Blink did so for the number of saccades, and wrong way for the saccade amplitude and speed. RE reached a tolerable level of 1.1 at 7 to 10 impulses for all measurements except the PR score. CONCLUSIONS: Our results suggest the necessity of removing artifacts after collecting VHIT samples to improve the accuracy and precision of results. Ten impulses are sufficient for achieving acceptable RE for all measurements except the PR score.

Visual Performance and Perception as a Target of Saccadic Strategies in Patients With Unilateral Vestibular Loss.

OBJECTIVES: To evaluate the ability of saccadic strategies developed during vestibular compensation to reduce the effect of an impaired vestibulo-ocular reflex (VOR) on a retinal smear and image motion sensation. DESIGN: Twenty patients with unilateral vestibular loss were examined with a video head impulse test before and after vestibular rehabilitation (VR) with the use of gaze stabilization and refixation saccades training. Head and eye velocity functions were processed to infer the retinal eccentricity, and through its correlation with visual acuity (VA), several measurements are proposed to evaluate the influence of VR on saccades behavior and visual performance. To isolate the effect of saccades on the findings and avoid bias because of gain differences, only patients whose VOR gain values remained unchanged after VR were included. RESULTS: Improved contribution of covert saccades and reduction of overt saccades latency were measured after VR. We found significant differences when assessing both the interval less than 70% VA (50.25 ms), which is considered the limit of a moderate low vision, and less than 50% VA (39.515 ms), which is the limit for severe low vision. Time to recover a VA of 75% (near normal) was reduced in all the patients (median: 56.472 ms). CONCLUSION: Despite the absence of VOR gain improvement, patients with unilateral vestibular loss are able to develop saccadic strategies that allow the shortening of the interval of retinal smear and image motion. The proposed measurements might be of use to evaluate VR outcomes and visually induced impairment.

[Clinical efficacy and polysomnography of adenotonsillectomy in the treatment of sleep-related respiratory disorders in children]. / Efectividad clínica y polisomnográfica de la adenamigdalectomía en el tratamiento de los trastornos respiratorios del sueño en los niños.

INTRODUCTION: If sleep-related breathing disorders in children are not treated quickly, they may be harmful to the child's future development. The best diagnostic test is polysomnography, since clinical assessments alone are not enough. Adenotonsillectomy is the most effective and widespread treatment for such disorders. OBJECTIVE: To assess clinical data on sleep-related breathing disorders, particularly in relation to behaviour and neurocognition, their long-term resolution with surgery and correlation with PSG data. METHOD: Prospective study with 73 children between 3 and 11 years of age, attending a special clinic for sleep-related breathing disorders. A medical history questionnaire was given to the parents, which included questions on the child's sleep patterns, respiratory disorders and behavioural and neurocognitive changes, and a polysomnography was carried out. Cases requiring surgery were monitored after 9 months by means of a further questionnaire and a follow-up polysomnography. RESULTS: Of the 73 children tested, 100 % snore, 87.5 % display objective apnoeas and 89 % suffer from nasal congestion. Drowsiness during the day was reported in only 28 %. Over 50 % of cases report aggressiveness or hyperactivity, while 41 % have concentration difficulties. In 61 of the 73 cases (83.6 %) given a pre-operative polysomnography, the mean apnoea-hypopnoea index was 6.44 (4.44). Postoperative follow-up is available for 44 cases, 29 of them with polysomnography. The resolution of clinical symptoms is highly satisfactory in these cases, but 5 patients (17.2 %) still have an apnoea-hypopnoea index of more than 3. CONCLUSIONS: Adenotonsillectomy is effective in curing the majority of sleep-related respiratory disorder symptoms in children. However, a significant percentage of cases display a persistent polysomnographic change. Long-term postoperative monitoring is recommended in such cases.

Vestibulo-ocular reflex gain values in the suppression head impulse test of healthy subjects.

OBJECTIVE: To assess whether there are differences in vestibulo-ocular reflex (VOR) gain for suppression head impulse (SHIMP) and head impulse (HIMP) video head impulse test paradigms, and if so, what are their causes. METHODS: Prospective multicenter observational double-blind nonrandomized clinical study was performed by collecting 80 healthy subjects from four reference hospitals. SHIMP data was postprocessed to eliminate impulses in which early SHIMP saccades were detected. Differences between HIMP and SHIMP VOR gain values were statistically evaluated. Head impulse maximum velocity, gender, age, direction of impulse, and hospital center were considered as possible influential factors. RESULTS: A small significant statistical difference between HIMP and SHIMP VOR gain values was found on repeated measures analysis of variance (-0.05 ± 0.006, P < 0.001). Optimized linear model showed a significant influence of age variable on the observed differences for HIMP and SHIMP gain values and did not find influence between gain values differences and maximum head impulse velocity. Both HIMP and SHIMP VOR gain values were significant lower (-0.09, P < 0.001) when the impulses were performed to the left side. CONCLUSION: We had observed a difference in SHIMP and HIMP gain values not adequately explained by known gain modification factors. The persistence of this slight but significant difference indicates that there are more factors causing lower SHIMP VOR gain values. This difference must to be considered in further studies as well as in the clinical SHIMP testing protocols. We hypothesized that VOR phasic response inhibition could be the underlying cause of this difference. LEVEL OF EVIDENCE: 2b. Laryngoscope, 128:2383-2389, 2018.

[Diagnosis of proximal gastro-oesophageal reflux in patients with rhonchopathy and sleep apnoea]. / Diagnóstico de reflujo gastroesofágico proximal en pacientes con trastornos respiratorios del sueño.

INTRODUCTION: The close relationship between gastro-oesophageal reflux disease and sleep-related breathing disorders allows the consideration of treatment with proton pump inhibitors as a feasible alternative for patients with snoring or mild to moderate sleep apnoea syndrome. Nevertheless, the presence of gastro-oesophageal reflux in the proximal oesophagus must be identified objectively with a double channel oesophageal pH-metry. OBJECTIVE: To identify clinical data allowing the selection of patients most likely to have proximal oesophageal reflux, and, therefore, candidates for oesophageal pH-metry. MATERIAL AND METHOD: Between January 2004 and September 2006, 121 patients were prospectively included. In these patients, a nocturnal polysomnography and a 24 hour double channel pH-metry were performed on the same day. We compared statistically the clinical data, endoscopic examination of the upper airway and the pH-metry results. RESULTS: A good correlation was observed between the presence of symptoms suggesting pharyngo-laryngeal acid reflux and endoscopic examination of this area (P< .009). However, the comparison between clinical data and pH-metry results was not statistically significant. CONCLUSIONS: Clinical symptoms and endoscopic examination alone are not good tools to determine the presence of gastro-oesophageal reflux in the pharynx, in this group of patients. Its presence must be ascertained by a double channel oesophageal pH-metry.

Vestibulo-Ocular Reflex Stabilization after Vestibular Schwannoma Surgery: A Story Told by Saccades.

OBJECTIVE: To evaluate vestibular compensation via measurement of the vestibulo-ocular reflex (VOR) following vestibular schwannoma surgery and its relationship with changes in saccades strategy after surgery. PATIENTS: Thirty-six consecutive patients with vestibular schwannomas, without brainstem compression, underwent surgical resection. Patients were recruited from University Hospital of Salamanca, Spain. METHODS: We assessed the age, sex, tumor size, degree of canalicular weakness, and preoperative video head impulse test (gain and saccade organization measured with PR score). Gain and saccade organization were compared with postoperative values at discharge and also at 1, 3, and 6 months. PR scores are a measure of the scatter of refixation saccades. RESULTS: Patients with normal preoperative caloric function had higher PR scores (saccades were scattered) following surgery compared to patients with significant preoperative canal paresis (p < 0.05). VOR gain and the presence of covert/overt saccades preoperatively did not influence the PR score (p > 0.05), but a group of patients with very low VOR gain (<0.45) and covert/overt saccades before surgery had lower PR scores after surgery. The differences after 6 months were not significant. CONCLUSION: Patients with more severe vestibular dysfunction before vestibular schwannoma surgery show significantly faster vestibular compensation following surgery, manifested by changes in VOR gain and PR score. The scatter of compensatory saccades (as measured by the PR score) may be a surrogate early marker of clinical recovery, given its relationship to the Dizziness Handicap Inventory.

A new method to improve the imbalance in chronic unilateral vestibular loss: the organization of refixation saccades.

CONCLUSION: VOR adaptation and organization of refixation saccades in a gathered pattern is a process that can be artificially induced in patients with unilateral vestibular loss who have not developed it naturally, improving imbalance and vestibular disability. OBJECTIVE: To test that temporary grouping of refixation saccades should be linked to better clinical status without gain recovery. METHODS: A training to induce the refixation saccades into gathered fashion is performed. The outcome measures are handicap level measured by the dizziness handicap index (DHI) and refixation saccades organization pattern measured by a numeric score called 'PR' given by a software developed by the authors. Analysis is done before the training and 1 and 3 months after ending, Non-parametric tests were used for statistical analysis. RESULTS: This study has included 10 healthy subjects (four males, six females), and 16 patients with chronic unsteadiness due to unilateral vestibular loss (nine vestibular neuritis, four post-surgical vestibular schwannoma, and three cases after intra-tympanic gentamycin in patients with Ménière's disease). The reduction in the DHI score was significant at 1 (p = 0.028) and 3 months (p = 0.042) post-treatment. Also, statistically significant differences were found between the PR score before and PR score 1 (p = 0.005) and 3 months after the treatment (p = 0.003).

Normative data on angular vestibulo-ocular responses in the yaw axis measured using the video head impulse test.

OBJECTIVE: To analyze vestibulo-ocular responses using the video head impulse test in the yaw axis. STUDY DESIGN: Prospective. SETTING: Tertiary and university hospital. PATIENTS: Two hundred twelve healthy subjects with no history of vestibular or neurologic impairment. INTERVENTION: Video head impulse test in the lateral semicircular canal plane. MAIN OUTCOME MEASURES: Vestibulo-ocular reflex (VOR) gain and appearance of refixation saccades (RSs) considering sex, age, and head impulse velocity and direction. RESULTS: Mean gain was 1.06 ± 0.07, and there were no differences between sexes. For all the impulses (n = 9,654; 4,947 rightward and 4,707 leftward), VOR gain decreased as head impulse velocity increased. When gain was evaluated by age and head velocity, it was steady until age 70 years for higher-velocity impulses and until age 90 years for lower-velocity head impulses. RSs were detected in 52 subjects, occurring after impulses to both sides of the head in 22 of these subjects. The number of subjects with RSs was significantly higher after age 71 years, and velocity was correlated, not with age, but with head impulse velocity. CONCLUSION: VOR gain was stable until age 90 years and thereafter dropped. However, this decrease occurred progressively in younger subjects as head impulse velocity increased, with VOR gain for faster head impulses decreasing significantly in subjects older than 70 years. This finding, in addition to the appearance of RSs, can be explained by the effect of aging on the deterioration of the vestibular system in the semicircular canals.

[Long-term persistence of obstructive sleep apnoea-hypopnoea syndrome in children treated with adenotonsillectomy. Analysis of prognostic factors]. / Persistencia a largo plazo del síndrome de la apnea-hipopnea obstructiva del sueño infantil tratada con adenoamigdalectomía. Análisis de factores pronósticos.

INTRODUCTION: Treatment of obstructive sleep apnoea-hypopnoea syndrome in children with adenotonsillectomy is effective but has a moderate rate of persistent disease. OBJECTIVES: To analyse the rate of persistence of sleep apnoea-hypopnoea syndrome in a group of adenotonsillectomy-treated paediatric patients and to assess the possible prognostic factors. METHODS: Prospective study of 80 patients aged between 2 and 13 years who had obstructive sleep apnoea-hypopnoea syndrome, treated with adenotonsillectomy. All patients had been followed up clinically and by polysomnography for 1 year after surgery. We analysed the epidemiological and clinical factors that could negatively affect the outcome of surgery. RESULTS: The median age was 5.25 ± 2.05 years and the mean apnoea-hypopnoea index (AHI) was 8.13 ± 6.06. One year after surgery, all clinical parameters improved significantly and the mean AHI was 2.50. Persistent disease (AHI≥3) was present in 21 of the patients (26.3%). The comparative analysis of clinical and epidemiological factors between the group of non-persistence and persistence did not obtain statistically-significant differences in age, sex, tonsillar size, Friedman degree or severity of preoperative disease. The only significant factor was that patients without persistence were more obese. CONCLUSION: The results of our study about the persistence of obstructive sleep apnoea-hypopnoea syndrome after adenotonsillectomy are significant enough to recommend follow-up with polysomnography, especially in high-risk groups. In the series presented here, we were not able to demonstrate these risk factors. Our results are probably conditioned by the characteristics of the population studied: Low age, low obesity rate and less severe levels of apnoea-hypopnoea index.

[Dentofacial development abnormalities in paediatric sleep-related breathing disorders]. / Alteraciones del desarrollo dentofacial en los trastornos respiratorios del sueño infantil.

INTRODUCTION: The recent interest in sleep-related breathing disorders has re-opened the old debate as to whether there is a causal relationship between upper respiratory obstruction and abnormalities in dentofacial development. OBJECTIVE: To establish the impact of dentofacial development on sleep-related breathing disorders in children. METHOD: This is a prospective study in which the dentofacial studies of 30 children, diagnosed with a sleep-related breathing disorder using polysomnography, were compared with a control group of 30 healthy children. The ages of both groups were between 3 and 13 years. RESULTS: The statistical analysis showed significant differences between the groups in the proportion of children with a narrow palate (83% of the problem group and 57% in the control; P=0.024) and cross bite (40% and 13%; P=0.020). On comparing the angles measured, the only statistically-significant difference was the skull base-mandibular plane angle: The problem children group had a mean of 37.59±5.56 and the control group, a mean of 34.41±4.62 (P=0.023). CONCLUSION: Children with sleep-related breathing disorders have abnormalities in facial and dental development caused by upper respiratory obstruction. These anomalies, vertical growth of the face, narrow palate and dental occlusion changes should be taken into account when assessing the indication for a adenotonsillectomy.

[Mandibular advancement devices for the treatment of adult sleep respiratory disorders]. / Dispositivos de avance mandibular para el tratamiento de los trastornos respiratorios del sueño del adulto.

INTRODUCTION: Mandibular advancement devices are being shown to be increasingly useful in the treatment of adult respiratory sleep disorders. A prospective study was started in April 2008 to apply 40 devices free of charge, with the aim of assessing their usefulness in our patients. MATERIAL AND METHODS: The device was applied to 40 patients with an apnoea-hypopnoea index of less than 40. All the cases snored, with 52.5% observed apnoeas and 47.5% diurnal sleepiness. RESULTS: With a minimum follow-up of six months, the cases that snored decreased to 59%, most with a significantly lower intensity; 8.8% of cases had observed apnoeas and 14.7% mentioned diurnal sleepiness. There was an overall clinical improvement in 31 (91.2%) patients. The mean apnoea-hypopnoea index fell to 8.4+/-9.6 and polysomnographic improvement could be seen in 25 (75%) cases. An overall positive result, showing subjective as well as objective improvement, was obtained in 23 (69.7%) patients. Two patients stopped using the device in the first few days and another patient after six months. Complications were relatively common, but always slight. Compliance levels were satisfactory: a mean of 6.5+/-1.1 nights per week and 7.4+/-1.09 days per week. CONCLUSION: Mandibular advancement devices are an effective therapeutic option for the treatment of respiratory sleep disorders. Compliance levels can be satisfactory if working with an expert odontology team.

[Clinical diagnosis and physical examination]. / Diagnóstico clínico y exploración física.

In children, medical history and meticulous examination are essential to the diagnosis and future treatment of all the alterations contributing to sleep breathing disorders. Examination of the oropharynx aids assessment of hypertrophy of the palatine tonsils, while fiberoptic endoscopy assists in the diagnosis of adenoid hypertrophy. Among radiological examinations, only cephalometry has proved to be useful in the study of the facial skeleton. Lateral radiography of the nasopharynx to study adenoid vegetations has been surpassed by fiberoptic endoscopy in terms of diagnostic performance. All examinations facilitate an etiological and topographical diagnosis of patients with sleep breathing disorders. The diagnosis of respiratory problems that affect children's dentofacial development can begin at a very early age, since early detection is essential to preventing the effects of these alterations on orofacial morphology and function. This article reviews the basic and additional dental examinations that should be conducted in children with upper airway obstruction and a medical history of sleep breathing disorders.