Neck flexion may play a role in the pathogenesis of Hirayama disease. Upper limb somatosensory evoked potentials were recorded in five patients with Hirayama disease, six patients with ALS, and 14 healthy subjects. Neck flexion caused a significant amplitude decrease of the N13 cervical response only in patients with Hirayama disease. Direct cord compression or microvascular changes can in theory account for this position-related dysfunction.
Cluster headache (CH) is a primary headache with a close relation to sleep. CH presents a circa-annual rhythmicity; attacks occur preferably during the night, in rapid eye movement (REM) sleep, and they are associated with autonomic and neuroendocrine modifications. The posterior hypothalamus is the key structure for the biological phenomenon of CH. Our aim is to describe a 55-year-old man presenting a typical episodic CH, in whom we performed a prolonged sleep study, consisting of a 9-week actigraphic recording and repeated polysomnography, with evaluation of both sleep macrostructure and microstructure. During the acute bout of the cluster we observed an irregular sleep-wake pattern and abnormalities of REM sleep. After the cluster phase these alterations remitted. We conclude that CH was associated, in this patient, with sleep dysregulation involving the biological clock and the arousal mechanisms, particularly in REM. All these abnormalities are consistent with posterior hypothalamic dysfunction.
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