33 - The Thalamus Regulates the Sleep-Wake Cycle and Autonomic and Endocrine Functions

Abstract

This chapter presents the findings obtained by monitoring several patients with fatal familial insomnia (FFI) and discusses their physiological implications. FFI starts between 35 and 61 years of life, and leads to death after 13 to 36 months after onset. It is inherited as an autosomal dominant trait. The cardinal features of FFI are insomnia, dysautonomia, and neurological motor disturbances. The principal neurophysiological finding is the virtually complete inability to generate electroencephalographic patterns of sleep. In some cases that are monitored by means of 24-hour polysomnography, sleep is completely absent some months before death; only brief repeated episodes of muscle tone loss persisted, associated with bursts of rapid eye movements. It is believed that the inability to generate sleep patterns and the loss of circadian vegetative and endocrine oscillations in FFI can be because of the massive damage to the anterior ventral (AV) and dorso-medial (DM) thalamic nuclei. This conclusion is supported by the fact that clinical features are remarkably similar in the cases where the lesion is confined to the AV and DM nuclei and in those with involvement of other thalamic and extrathalamic structures.