Gait instability caused by vestibular disorders - analysis by tactile sensor.

OBJECTIVE: To elucidate instability of gait performance in patients with vestibular lesions by the use of a tactile sensors placed under both feet. METHODS: Gait analysis was conducted by the use of tactile sensors in 92 patients who had various types of vestibular lesions including vestibular neuritis (VN), acoustic neuroma (AN), and spinocerebellar degeneration (SCD). 26 healthy adults served as a control. Variables were coefficient of variation of stance, swing, and double support durations. Morphological analysis of foot pressure progression during stance was also performed. In addition, differences in each foot's integrated foot pressure in a gait test were measured, especially in cases with unilateral vestibular lesions. All data was comparatively analyzed between each pathological group and control group. A comparative study between intact side foot and lesion side foot was performed in those unilateral vestibular disorder cases as well. RESULTS: Those gait phase related variables were significantly greater in the pathologic group than in the control group, especially under gait with eyes closed. Morphological irregularity of foot pressure progression during stance was shown in cases with VN and SCD and was greatest in SCD cases. As for integrated foot pressure, in most cases with VN, it has become greater in the lesion side foot, suggesting that body center of gravity could shift toward the lesion side during gait. CONCLUSIONS: Gait analysis by the use of tactile sensors could provide additional important information regarding vestibular patho-physiology in patients with vestibular system disorders. Accordingly, gait performance tests should also be taken into consideration as a vestibular function test for patients with vertigo.

A preliminary study on the influence of obstructive sleep apnea upon cumulative parasympathetic system activity.

OBJECTIVE: Although the autonomic nervous system plays a key role in mediating cardiovascular changes during obstructive sleep apnea (OSA), parasympathetic nervous system (PNS) activity during sleep apnea has not yet been sufficiently investigated. This study is to discuss the relationship between PNS activity and OSA. METHODS: Polysomnography recording was carried out in 76 patients (71 male and 5 female) with OSA. Cumulative PNS activity during sleep for each patient was derived from time series data of electrocardiogram (ECG) and analyzed by coarse graining spectral analysis of heart rate variability. The correlation between cumulative PNS activity and apnea-hypopnea index (AHI) was then discussed. RESULTS: Cumulative PNS activity and PNS peaks during sleep were lowly but significantly correlated with OSA severity (r=-0.344, p<0.005; and r=-0.266, p<0.05 respectively), and a linear regression equation could be established. Furthermore, significant correlation was also observed in the adult groups and in the moderate and severe groups, but not in the juvenile and the elderly and mild groups. CONCLUSION: These findings indicated that PNS function was obviously influenced by OSA during sleep. Cumulative PNS activity level might also serve as a useful parameter for the evaluation of OSA.

[N100m findings of auditory-evoked fields in patients with psychogenic hearing impairment].

We recorded the auditory-evoked fields in five patients with psychogenic hearing impairment and ten healthy controls. The maximum N100m peak amplitude and latency were measured under 1000 and 2000-Hz tone burst stimuli in each ear. The mean N100m amplitude in the patients was smaller than that in the controls. Especially, regardless of the side of stimulation, the mean amplitude in the left-hemisphere was significantly smaller in the patients than in the controls, except for the 2000-Hz stimulus condition in the left ear. There was no significant difference in the latency of the N100m peak between patients and controls. We attribute the findings of attenuation of the N100m amplitude to the peculiar auditory perception in patients with psychogenic hearing impairment. Concerning the cause of this finding, we suggest two possible mechanisms: inhibitory auditory processing and attention deficit.

A preliminary study on application of portable monitoring for diagnosis of obstructive sleep apnea.

Portable monitoring (PM) for diagnosis of obstructive sleep apnea has developed recently. Many studies were performed in the laboratory setting, with simultaneous polysomnographic recordings or required technical assistance in the home setting. And the data were automatically analyzed. In this study, we attempted to evaluate whether PM could be useful in fully unattended home setting, and whether the auto analysis of the data is reliable. Home setting examination by Stardust II, a novel PM device, was performed unattendedly on consecutive 62 patients who complained of snoring. The questionnaire survey on the difficulty of fitting and operation, and the discomfort was conducted by visual analog scale. Automatically and manually analyzed results were compared. The examination was successfully performed by all subjects. The difficulty of fitting and operation, and the discomfort were 2.9+/-1.9, 1.8+/-1.2 and 3.6+/-2.1, respectively. Auto analysis differed significantly from manual analysis not only in apnea/hypopnea index (AHI), but also in the construction of sleep disordered respiratory events. Although AHI in automatic and manual analysis had a good correlation (r=0.949; P<0.001), their agreement was poor, especially in mild and moderate cases. However, setting AHI=50 as a cut-off point in auto analysis, sensitivity and specificity could reach 100% and 92.5%, respectively. Accordingly, PM is useful to identify obstructive sleep apnea in an unattended home setting condition. Considering the significant difference between automatic and manual analysis, we suggest that the data analysis should be performed manually.

Gait instability in patients with acoustic neuroma.

OBJECTIVE: To investigate pathological gait in patients with unilateral acoustic neuroma using tactile sensors placed under both feet. MATERIAL AND METHODS: Forty-three patients were enrolled in the study. They were categorized into two groups: the small tumor group had tumors < 2 cm from the porus acousticus without any brainstem compression and the large tumor group had tumors > 2 cm from the porus acousticus with brainstem compression. Eighteen healthy subjects served as controls. Subjects were asked to walk freely with eyes open or closed for a distance of nearly 8 m. The coefficients of variation (CVs) of stance, swing and double support were calculated. The stability of the trajectories of the center of force and the foot pressure difference were also studied. RESULTS: The CVs of stance, swing and double support were significantly greater with eyes closed and, with the exception of double support, these differences were greater in the tumor groups. The instability of the trajectories of the center of force was significantly greater in the tumor group, and in the large tumor group the horizontal component of sway movement of the trajectories of the center of force of the foot on the same side as the lesion was greater than that on the intact side with eyes closed. Regarding foot pressure differences between the two feet, the large tumor group had a greater foot pressure for the foot on the same side as the lesion than for the foot on the intact side, especially with eyes closed. No significant difference was found in the small tumor group. CONCLUSION: The presence of acoustic neuroma may cause unstable gait, and steady gait is considerably dependent on visual input. Larger tumors may produce shifts in the body's center of gravity to the lesioned side during gait, especially under conditions of visual deprivation. These abnormalities may reflect some influences on gait control systems such as phase and muscular tonus control systems.

Using an air-pad sensor for the diagnosis of sleep apnea: a trial study.

An air-pad sensor (APS) was developed to record respiratory effort non-invasively. The APS is placed under the subjects' bodies and acoustic signals received by the pad are analysed. Nine patients with obstructive sleep apnea (OSA) and two healthy subjects were examined using an APS and daytime polysomnography, including intraesophageal pressure (Peso), simultaneously. The agreement ratio in terms of the central apnea time between the APS and the Peso was 93.4%, although the ratio between the Peso and an abdominal strain gauge was 40.7%. The agreement ratio in terms of respiratory rate among the Peso, APS, and abdominal strain gauge in patients with OSA was high; but the agreement ratio was low (74.4%) between the Peso and the strain gauge in mixed apnea.

Facial pattern categories of sleep breathing-disordered children using Ricketts analysis.

The facial patterns of 29 children under the age of 15 years with tonsil and/or adenoid and sleep disorder problems was analysed. The lateral-cephalograms of these patients was digitized in a zero-based computer program using Ricketts analysis to examine facial patterns. Results of the analysis were compared with the mean of the control group, n = 41 (9-year-old Japanese children). There were significant differences (P < 0.01-0.001) between the patient group and the control group when comparing the facial axis, lower facial height, mandibular arc, total facial height, and McNamara-Pogonion. The facial pattern of children with sleep breathing disorders was discovered to be the dolico facial pattern.

Effectiveness of a tongue-retaining device.

The effectiveness of a tongue-retaining device (TRD) was examined at the baseline without any TRD [TRD(-)] and then with a TRD [TRD(+)] in eight patients with obstructive sleep apnea (OSA). In terms of the 3+ % oxygen desaturation index (ODI3), lowest percutaneous oxygen saturation (SpO2), and time spent SpO2 < 90%, there were significant differences (P < 0.01-0.05) between the findings for TRD(-) and TRD(+). The ODI3 dropped below the baseline by more than 50% in five patients (63%) and dropped to fewer than 10 events/ h in six patients (75%). The results indicate that oral appliances help patients with mild to moderate OSA; however, patients with more severe OSA may also be treated effectively with a TRD.