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mise à jour du 24 février 2002
Appl Neuropysiol
cas cliniques
 Post lesion yawning and thalamotomy site
MF Jurko and OJ Andy
Department of neurosurgery, University of Mississipi, Jackson


Yawning and stroke

Abstract. Yawning during hyperventilation occurred in certain patients post-thalamotomy. It was found that all of the lesions which elicited yawning (during the routine recording of electroencephalograms) were localized te, the medial portion of the center-median nucleus. Yawning was noted to persist up to 31/2 years postsurgery. Another group of patients who yawned when hyperventilated were patients with a history of a recent head injury whe showed post-traumatic behavioral changes. Patients in both groups were young. There was no direct relationship between yawning and EEG abnormality. It was suggested that yawning during hyperventilation may serve as a sign of brain damage, especially at the brain stem level, in young patients.

Following surgery certain patients who had stereotaxic lesions placed in the thalamus were observed to yawn while hyper-ventilating. During the routine recording of electroencephalograms it was discovered that these patients began to yawn during hyperventilation and they stopped yawning when hyperventilation was terminated. It was found that all of the lesions which elicited this yawning were located in the medial portion of the center-median nucleus and that all of the patients were young. Another group of patients who yawned when hyperventilated provided a provocative comparison with the lesion patients. These were patients with a history of a recent head injury who showed post-traumatic behavioral changes. It is considered significant that all of these patients were also young.

Six patients undergoing thalamotomy for seizure and behavioral disorders were observed to yawn when hyperventilated post-surgery. Three of the patients were 21-23 years old, 2 patients were 15 years old and 1 patient was age 11 years. Examination of the scattergram reveals that all of the yawners had lesions 8 mm or less laterally from the midline. A comparison of the number of patients who yawned with lesion placements within 8 mm from the midline to those lesions beyond 8 mm was highly significant by Fisher's exact probability test (p=0.003). Further examination of the scattergram shows that all of the yawners had lesions in the centermedian lesions was also, significant (p=0.014). This leads one to conmedian lesions was also significant (p=0.014). This leads one to conclude that lesions in the medial part of the center-median nucleus are more likely to, result in yawning than lesions in the lateral center-median or other areas of the thalamus. Moreover, lesions in the young are more 'A' student, but afterwards he barely passed. The patient's memory was impaired; he did not remember what he was told. He had altered reaction to pain consisting of decreased awareness of pain. For example, he sustained second- and third-degree burns on his calf unaware that he was too close to a radiant heater. After the accident, when spanked, he laughed rather than crying or screaming. Two EEGs taken 24 days apart, 1 year after injury, revealed a mildly abnormal 7- to 10-eps background frequency with the slower frequencies predominating. Yawning was precipitated by hyperventilation during both EEG recordings. In figure 2 the three episodes of yawning which occurred during hyperventilation in the second EEG are illustrated. Note the first yawn at 18 sec, the second at 65 sec, and the third at 107 sec.

Yawning and EEG Abnormality : All of the surgery patients had abnormal presurgery EEGs. Three of the patients had spike-wave discharges in their EEGs, 2 patients showed generalized (theta range) slowing, and 1 patient had focal delta left frontal. For the trauma patients, 5 patients had a slow background frequency (4 with biocciptal sharp waves and 1 with 14 sec positive spikes), 1 patient had generalized spike-wave discharges, 1 patient showed focal spikewave left frontal, and 1 patient had a normal EEG. Although 13 of the 14 yawners had abnormal EEGs, there was no direct relationship between yawning and the severity of the EEG abnormality.

Yawning and Persistence in Time : The surgery patients were seen 5 days postoperative and at 2- to 6-month intervals. Yawning was elicited during hyperventilation in all of these patients at the fifth postoperative day. Three of the patients continued to show yawning 2-31/2 years following surgery; 3 patients still yawned 1 year postoperatively, and 1 patient yawned at 2 months but did not yawn when seen 6 months later. Six of the 8 trauma patients were followed 1-3 years after the initial examination. The number of EEGs obtained ranged from 2 to 8 EEGs and yawning occurred in at least two thirds of the EEGs. In 2 cases which were followed for 2 months there was yawning in 2 out of 3 EEGs in the first case, and yawning in 1 of the 2 EEGs in the second case. It should be noted that in one of the patients yawning did not occur until 18 months after the initial examination (26 months after injury) and then was present in all of the 3 EEGs done within the next year. It appears that for both surgery and trauma patients there is a persistence of yawning following its first appearance. The mean number of yawns per 3-min hyperventilation was 3.0 for the surgery patients and 4.3 for the trauma patients.

Discussion : Yawning is a well-established response in the emotional pattern of sub-human primates and rnan. It may occur in human beings in such mild conflict states as boredom and embarrassment and is even simulated in nonverbal communication. Although primates as the chimpanzee and the gorilla may yawn in response to disturbance, yawning is so prominently displayed in the baboon that it may be regarded as a stereotyped response. Both threat yawns and tension yawns have been described. This increased frequency of yawning in the less highly developed baboon is of interest when contrasted with our finding that yawning in hyperventilation was confined to the young brain-injured patient. These maturational aspects are further highlighted in the descriptions of yawning in young chimpanzees which typically occurred when they were unable to take bananas in the presence of their superiors.

The findîng that surgical lesions in the medial part of the center-median nucleus produced yawning, whereas lateral lesions did not, is compatible with other evidence for functional specificity in the center-median nucleus. For Necker cube reversal rates it was found that lesions placed medially in the center-median nucleus increased reversal rate in contrast to laterally placed lesions which decreased the rate of reversal. Another study indicated that the lesion site within the center-median nucleus was related to the degree of improvement for specifie behavioral categories. For aggression maximum improvement occurred for medially placed lesions, whereas there were no differences in degree of improvement for hyperkinesia and patho-affect relative to medially or laterally placed lesions.

Yawning was elicited by bilateral stimulation of the cingulurn in two 17-year-old brain-damaged patients. Motor and behavioral responses such as restlessness and screaming also occurred. The authors suggest that they were chiefly stimulating the fibers that connect the cingulurn to the temporal lobe and other structures of the limbic system. They emphasized that the two patients were significantly brain-darnaged and their behavior, as a rule, was destructive and aggressive. Their report is compatible with cour observations and lends support to the speculation that young patients who yawn while hyperventilating, particularly those with behavioral symptorns, may well have brain damage involving subcortical structures, especially at the brain stem level. If this is the case then having the patients hyperventilated and observing yawning might be a simple, though useful, diagnostic tool.