Research in Review

Abstracts obtained from PubMed

Vasovagal Syncope Interrupting Sleep?

Heart. 2004 May;90(5):e25.

Krediet CT, Jardine DL, Cortelli P, Visman AG, Wieling W.

Department of Internal Medicine, Academic Medical Centre/University of Amsterdam, Amsterdam, The Netherlands.

Clinical data are reported for 13 patients who were referred with recurrent loss of consciousness at night interrupting their sleep. Most of the patients were women (10 of 13) with a mean age of 45 years (range 21-72 years). The histories were more consistent with vasovagal syncope than with epilepsy. This was supported by electroencephalographic and tilt test results. More polysomnographic monitoring data are required to confirm the diagnosis of vasovagal syncope interrupting sleep. This will be difficult because, although the condition may not be rare, the episodes are usually sporadic.

Editor's notes
by Michelle Sawicki

This study reported on thirteen people who had described loss of consciousness interrupting continuous sleep at night. There were ten women and three men, with a mean age of forty-five years. All patients filled the diagnostic criteria for vasovagal syncope with very high levels of certainty (>90%) based on an algorithm derived from a recent study that explored the historical criteria distinguishing syncope from seizures.

The authors state, "They all gave a history of waking up at night with nausea and urge to defecate. In some patients, syncope (fainting) occurred in bed; in others immediately after leaving the bed in an effort to get to the toilet. The syncope was of short duration and was often accompanied by profuse sweating. After regaining consciousness most patients felt very weak and could not remain upright, but were orientated. Bradycardia was documented in five patients. The frequency of attacks varied from weekly to annually and there was no relation to menstruation or alcohol. Three patients reported nightmares immediately before the episode. Some patients had learned to partially abort the episodes by remaining supine in bed. Nine patients also had daytime syncopal and presyncopal episodes associated with vasovagal symptoms."

The authors report that physicians, due to current teachings, are reluctant to diagnose vasovagal mechanisms when fainting occurs while lying down. They cite material showing that such reactions have been frequently observed during venesection, surgical procedures and cardiac catheterization. They also postulate several mechanisms that may account for syncope occurring while lying down. While the authors admit their findings are only preliminary and that their data is incomplete, they do think that patients who have nocturnal loss of consciousness with classical vasovagal prodromal symptoms may have true vasovagal syncope.

Relationships Between the Autonomic Nervous System and the Pancreas Including Regulation of Regeneration and Apoptosis: Recent Developments.

Pancreas. 2004 Aug;29(2):E51-E58.

Kiba T.

Third Department of Internal Medicine, Yokohama City University, School of Medicine, Yokohama, Japan.

Substantial new information has accumulated on the mechanisms of secretion, the development, and regulation of the gene expression, and the role of growth factors in the differentiation, growth, and regeneration of the pancreas. Many genes that are required for pancreas formation are active after birth and participate in endocrine and exocrine cell functions. Although the factors that normally regulate the proliferation of the pancreas largely remain elusive, several factors to influence the growth have been identified. It was also reported that the pancreas was sensitive to a number of apoptotic stimuli. The autonomic nervous system influences many of the functions of the body, including the pancreas. In fact, the parasympathetic nervous system and the sympathetic nervous system have opposing effects on insulin secretion from islet beta cells; feeding-induced parasympathetic neural activity to the pancreas stimulates insulin secretion, whereas stress-induced sympathetic neural activity to the pancreas inhibits insulin secretion. Moreover, it has been reported that the autonomic nervous system is one of the important factors that regulate pancreatic regeneration and stimulate the carcinogenesis. The present review focuses on the relationships between the autonomic nervous system and the pancreas, and furthermore, presents evidence of the autonomic nervous system-related pancreatic regeneration and carcinogenesis.

Sleep Disorders in Multiple System Atrophy

Neurologia. 2004 Jul;19(6):307-11.

Santamaria J, Iranzo A, Tolosa E.

Servicio de Neurologia. Hospital Clinic de Barcelona. Barcelona.

Sleep disorders are so common in multiple system atrophy that they should be considered an integral part of the disease. Sleep fragmentation occurs in more than half of the patients, with sleep onset and sleep maintenance insomnia. Periodic leg movements of sleep are also common, although they are generally asymptomatic. REM sleep behavior disorder, a parasomnia in which the patient presents vigorous movements associated with intense dreaming dreaming during REM sleep, is detected polysomnographically in almost all the patients with variable severity. Nocturnal stridor is produced by obstruction on the glottis level. The cause of stridor is unknown but two alternative explanations have been proposed: paralysis of the muscles opening the vocal chords and excessive contraction of the muscles that close them. A combination of both, however, is the most likely explanation. Nocturnal stridor is associated with decreased survival and its treatment is based on continuous positive air pressure (CPAP) when it occurs only during sleep or tracheostomy when it worsens and becomes also diurnal.

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