mise à jour du
1 novembre 2001
J Neurology
1999; 246; 621-622
cas cliniques
 Pathological yawning (chasm) associated with periodic leg movements in sleep: cure by levodopa
Martin Leonhardt, Michael Abele, Thomas Klockgether, Johannes Dichgans, Michael Weller
Department of neurology, University of Tübingen, Medical School - Hoppe Seyler Strasse3 D72076 Tübingen, Germany
Yawning is a complex arousal defense reflex generated in the reticular brainstem that has a peripheral and central arc and is thought to counteract brain hypoxemia Excessive or pathological yawning, "chasm", is defined as a compulsive, repetitive action which is not trigered by "physiological" stimuli such as fatigue or boredom.

A 44 year-old Irish woman was admitted because of sudden onset of pathological yawning. Her excessive pathological yawning caused her to be socially extremely handicapped. She reported sleeping well but felt tired again 2 h after awakening and had several naps befor evening. Snoring and apnea were denied; there was no evidence of restless leg syndrome. There was a history of hypertension for 5 years, which had been treated with nifedipine. She neither drank alcohol nor smoked. Physical examination showed a mild left central hemiparesis, which had escape the patient's notice, and moderate obesity. The patient suffered excessive repetitive, compulsive yawning that she was unable to control for longer than 1 mn. Routine blood tetst, EEG, and CSF findings were normal. Cranial magnetic resonanceimaging showed some small, presumbly ischemic lesions in the frontal periventricular region on both sides. There were no brainstem lesions.

All night polysomnography revealed disturbed sleep structure with awakenings, poor cyclic structure, and borderline fragmentation of sleep. There were no apneas or hypoxemias. Mainly in the first third of the night, periodic leg movements appeared during sleep stages 1 or 2, with typical arousals including K-complexes and alpha activation. During the rest of the night there was frequent rhythmic activity of the facial muscles, determined by chin muscle activity measured by sub-mandibular electrodes (bruxism). Altogether, 116 movements were enregistred during 8 h of sleep, most of them associated with arousals. The movements of face and legs were not synchronous. A diagnosis of periodoc leg movements in sleep (PLMS) was made according to criteria of the American Sleep Disorders Association. The patient was put on long action levodopa (100mg) at night.

Yawning disapperead promptly, and the patient felt more alert and active during the day. The effects of the treatment on yawning were assessed by video-recording. After discharge the patient increased the levodopa dose to 200 mg. At follow up 4 weeks later, she was virtually free of yawning and hypersomnia. However, the were side effects from the levodopa, including depreesed mood, nightmares, and sligt periods of disorientation during awakenings in the night. Polysomnographic findings were rather normal now, with 55 movements registered and more considered normal. A drug holyday precipited a relapse of chasm and fatigue within a few days. Polysomnography was not performed on that occasion. After restitution of levodopa 100mg the patient was almost free of symptoms and without serious side effects. Another follow-up after 4 weeks showed the patient in stable condition. Six months later the patient discontinued the medication and has suffered no relaps since.

This is the first case of PLMS associated with pathological yawning. Known causes of pathological yawning include encephalitis, seizures, tumors of the fourth ventricule region, multiple sclerosis, progressive supranuclear palsy, electroconvulsive therapy and neuroleptic withdrawal. Valproate overdose, dopamine agonists, imipramine, withdrawal from morphine and estrogen substitution may also induce pathological yawning.

Neuropharmacological experimental studies show that dopaminergic, cholinergic, ACTHergic and oxytocinergic systems are part of the complex behavioral response of yawning. Studies in man have stressed the importance of the dopaminergic system in the generation of yawning. Apomorphine in low doses induces yawning (and penil erection) in man and rats. This is probably due to a stimulation of presynaptic D2 autoreceptors, which results in a net reduction in dopamine releases. Dopamine agonists at higher doses do not produce yawning in rats, suggesting that reduced rather than enhanced dopaminergic stimulation mediates yawning reponse.

PLMS has also been linked to alterations in dopaminergic neurotransmission. The therapy of choice is levodopa or dopamine agonists. Here, we treated pathological yawning and PMLS successfully with levodopa. Since chasm was much more prominent than the day-time hypersomnia, we doubt that the remission of yawningwith levodopa therapy simply resulted from the reduction of hypersomnia after improvement in night sleep. Thus the present case study raises the possibility that chasm and PLMS reflect a common disturbance of dopaminergic neurotransmission. Transient withdrawal of levodopa precipited the relapse of pathological yawning and thus confirmed its therapeutic efficacy. Sudden onset and delayed resolution of the symptom favor a circumscribed ischemic lesion as a likely cause of both PLMS and chasm in our patient. We conclude that a therapeutic trial of levodopa is justified in patients with pathological yawning.