Interaction of somatosensory evoked potentials within the same nerve and between the two different nerves: including high-frequency oscillation (HFO).
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Electric Stimulation↗
Biomedical subjects
Thoru Yamada
Publications and source records attributed to Thoru Yamada.
REM alpha rhythm: diagnostic for narcolepsy?
SUMMARY: A young man, in whom narcolepsy was subsequently diagnosed, had the simultaneous onset of quadriparesis and a rapid eye movement (REM)-sleep polysomnographic pattern. During this REM-sleep pattern, a waking alpha EEG rhythm, appearing when he was asked to close his eyes, immediately attenuated when he was instructed to open his eyes, after which the REM-sleep pattern persisted. The juxtaposition of REM sleep patterns and reactive alpha rhythms are likely unique to sleep paralysis and may prove valuable in diagnosing narcolepsy.
Adolescent↗
Experimental scoliosis in melatonin-deficient C57BL/6J mice without pinealectomy.
The etiology of idiopathic scoliosis is unknown. Scoliosis with many characteristics closely resembling those seen in idiopathic scoliosis has been produced in young chickens and bipedal rats after pinealectomy. In this study, we induced experimental scoliosis in C57BL/6J mice without pinealectomy and melatonin treatment suppressed the development of scoliosis. A total of 100 mice were divided into four groups: 20 quadrupedal mice served as controls; 30 mice underwent resection of two forelegs and tail at 3 wk of age (bipedal mice); the remaining 20 quadrupedal and 30 bipedal mice received intraperitoneal melatonin (8 mg/kg BW) at 19:00 hr daily. Before killing, blood samples were collected in the middle of dark cycle and melatonin levels were measured by radioimmunoassay. Spine X-ray and helical 3D-CT were examined after killing at 5 months of age. The bipedal mice without a tail were able to walk with standing posture, whereas the quadrupedal mice did not walk with standing posture. In C57BL/6J mice, the serum melatonin was reduced to nearly zero; however, the normal level was restored in both bipedal and quadrupedal mice after the injection of melatonin. Scoliosis with rib humps developed in 29 of 30 bipedal and in five quadrupedal mice. None of mice with melatonin treatment developed scoliosis. The results suggest that melatonin deficiency in bipedal mice appears to play crucial role for development of scoliosis. Also the restoration of melatonin levels prevents the development of scoliosis.
Animals↗
Rib length in experimental scoliosis induced by pinealectomy in chickens.
STUDY DESIGN: This study was designed to investigate the difference of rib length of idiopathic scoliosis using experimentally induced scoliosis by pinealectomy in chickens. OBJECTIVE: To find whether the difference of rib length may play a role for the development of scoliosis in pinealectomized chickens. SUMMARY OF BACKGROUND DATA: In experimental and clinical studies, asymmetric growth of the rib has been considered to be one of factors for the development of idiopathic scoliosis. Pinealectomy in chickens consistently produces scoliosis with lordosis, vertebral rotations, and rib humps, which have anatomic characteristics similar to those of human idiopathic scoliosis. METHODS: A total of 30 chickens were divided into two groups: pinealectomy in 15 chickens and sham operation in 15 chickens served as control. The surgeries were performed on the second day after hatching. The chickens in both groups were killed at 3 months of age. The spines were examined radiologically for the presence of a scoliotic curve. Also, the ribs at each level were measured and compared between left and right sides. RESULTS: All pinealectomized chickens that developed scoliosis showed rib humps. In contrast, none of chickens in a sham operation developed scoliosis. In both groups, there were no significant asymmetries in the rib length. CONCLUSION: Our results indicated that rib length was not related to the experimental scoliosis examined in this study. Further study is encouraged to investigate if the asymmetric rib length plays a role in causing or promoting other types of scoliosis, especially in primate or human idiopathic scoliosis.
Animals↗
Pathological mechanism of idiopathic scoliosis: experimental scoliosis in pinealectomized rats.
The pathological mechanism of curve progression in idiopathic scoliosis is still obscure. In this study we investigated the pathological mechanism of idiopathic scoliosis in experimentally induced scoliosis in rats. A total 30 rats were divided into three groups: ten bipedal rats with a sham operation, which served as the control; ten quadrupedal rats with pinealectomy; and ten bipedal rats with pinealectomy. Scoliosis developed only in pinealectomized bipedal rats and not in pinealectomized quadrupedal rats. Cervicothoracic lordosis developed in bipedal rats with or without pinealectomy. These deformities of lordoscoliosis in pinealectomized bipedal rats were similar to human idiopathic scoliosis. Lordosis or lordotic tendency was sufficient to cause the spine to rotate to the side. Rotational instability of the spine with rotation of lordotic segment appears to produce a characteristic scoliotic deformity as a secondary phenomenon. Our findings suggest that lordosis may develop in bipedal rats, but pinealectomy is required for the development of lordoscoliosis. Balanced muscle tone controlled by the postural reflex is important to maintain normal posture with a straight spine in the bipedal condition. The disturbance of equilibrium and other postural mechanisms secondary to a deficiency of melatonin after pinealectomy may promote development of lordoscoliosis with vertebral rotation especially in the bipedal posture.
Animals↗
Narcolepsy and disorders of excessive somnolence.
Recent studies provide valid criteria that help differentiate idiopathic narcolepsy from other disorders of excessive daytime somnolence [3]. Research to date suggests that idiopathic narcolepsy might properly be considered a disorder of excessive sleepiness with dysfunctional REM-sleep mechanisms, clinically evidenced as cataplexy and electrophysiologically recognized as SOREMPs. Given these criteria, a diagnosis can generally be made using a combination of history, PSG, and MSLT. Traditionally, the medical treatment of idiopathic narcolepsy has centered on a two-drug regimen (stimulants for sleepiness and TCAs for cataplexy and auxiliary symptoms). Some newer medications are proving efficacious for sleepiness with minimal adverse effects, whereas others may provide a single-drug regimen that simultaneously addresses sleepiness and cataplexy [18]. New research has allowed some experts to hypothesize that idiopathic narcolepsy may be the result of a genetic predisposition to autoimmune disease [176]. It is possible that aberrant genetic coding of elements in the hypocretin/orexin systems allows a sensitivity to inducible and possibly virally mediated changes, which leave cells in the lateral hypothalamus susceptible to autoimmune attack [96]. As such, genetic screening of high-risk individuals might eventually rationalize the prophylactic use of immunosuppressants in some instances. In the future, for atypical cases(poorly responsive to therapy), genetic, CSF, and brain imaging studies, and possibly even neuronal transplantation may prove beneficial in the assessment and treatment of idiopathic narcolepsy.
Cataplexy↗
Obstructive sleep apnea associated with cerebral hypoxemia and death.
An increase in the arousal threshold may predispose critically ill patients with obstructive sleep apnea (OSA) to prolonged apneas and death during sleep. We report two cases in whom polysomnographically documented OSA resulted in EEG changes compatible with cerebral hypoxemia with subsequent respective transient encephalopathy in one instance and death in the other.
Adenocarcinoma↗
Fundamental principles of somatosensory evoked potentials.
Studies of SSEP provide unique opportunities for investigating physioanatomic substrates of sensory pathway and cognitive functions of the sensory system. Progress of clinical investigation and application of SSEP have been stalled in more recent years, although SSEP still remain a useful tool for diagnosis of various neurologic disorders and for the monitoring of spinal cord function during surgery. Reflecting complex sensory system in human, scalp-recorded SSEP consists of multiple waves, having different distribution, amplitude, and latencies among different electrodes. The physioanatomic significance of these multiple waves, especially the late components, is largely unknown. These should be explored further, especially in relation to cognitive function.
Electric Stimulation↗
Transient obstructive sleep apnea and asystole in association with presumed viral encephalopathy.
Evidence suggests that untreated obstructive sleep apnea (OSA) can lead to hypertension, cardiovascular disease, and stroke. Conversely, the systemic effects of a wide variety of critical illnesses can lead to CNS dysfunction, which can precipitate respiratory failure. Reported is a patient in whom an acute encephalopathy may have been responsible for transient OSA.
Adult↗