Modifications of thermoregulation in patients with suprasellar pituitary adenomas

Alterations in diurnal rhythmicity in patients treated for nonfunctioning pituitary macroadenoma: a controlled study and literature review

OBJECTIVE

Patients treated for nonfunctioning pituitary macroadenomas (NFMAs) have fatigue and alterations in sleep characteristics and sleep-wake rhythmicity frequently. As NFMAs often compress the optic chiasm, these complaints might be related to dysfunction of the adjacent suprachiasmatic nucleus (SCN). We aimed to explore whether indirect indices of SCN functioning are altered in the long term after surgery for NFMAs.

METHODS

We studied 17 NFMA patients in long-term remission after transsphenoidal surgery, receiving adequate and stable hormone replacement for hypopituitarism, and 17 control subjects matched for age, gender, and BMI. Indirect indices of SCN function were assessed from 24-h ambulatory recordings of skin and core body temperatures, blood pressure, and salivary melatonin levels. Altered melatonin secretion was defined as an absence of evening rise, considerable irregularity, or daytime values >3 pg/ml. We additionally studied eight patients treated for craniopharyngioma.

RESULTS

Distal-proximal skin temperature gradient did not differ between NFMAs and control subjects, but proximal skin temperature was decreased during daytime (P=0.006). Core body temperature and non-dipping of blood pressure did not differ, whereas melatonin secretion was often altered in NFMAs (OR 5.3, 95% CI 0.9-30.6). One or more abnormal parameters (≥2.0 SDS of control subjects) were observed during nighttime in 12 NFMA patients and during daytime in seven NFMA patients. Similar patterns were observed in craniopharyngioma patients.

CONCLUSION

Heterogeneous patterns of altered diurnal rhythmicity in skin temperature and melatonin secretion parameters were observed in the majority of patients treated for NFMAs. On a group level, both NFMA and craniopharyngioma patients showed a lower daytime proximal skin temperature than control subjects, but other group averages were not significantly different. The observations suggest altered function of central (or peripheral) clock machinery, possibly by disturbed entrainment or damage of the hypothalamic SCN by the suprasellar macroadenoma or its treatment.

Comparison of propofol versus sevoflurane on thermoregulation in patients undergoing transsphenoidal pituitary surgery: A preliminary study

PURPOSE

General anesthesia causes inhibition of thermoregulatory mechanisms. Propofol has been reported to cause more temperature fall, but in case of deliberate mild hypothermia, both sevoflurane and propofol were comparable. Thermoregulation is found to be disturbed in cases of pituitary tumors. We aimed to investigate which of the two agents, sevoflurane or propofol, results in better preservation of thermoregulation in patients undergoing transsphenoidal excision of pituitary tumors.

METHODS

Twenty-six patients scheduled to undergo transsphenoidal removal of pituitary adenomas were randomly allocated to receive propofol or sevoflurane anesthesia. Baseline esophageal temperature was noted. Times for temperature to fall by 1°C or 35°C and to return to baseline were also comparable (P>0.05). After that warmer was started at 43°C and time to rise to baseline was noted. Duration of surgery, total blood loss, and total fluid intake were also noted. If any, side effects such as delayed arousal and recovery from muscle relaxant were noted.

RESULTS

The demographics of the patients were comparable. Duration of surgery and total blood loss were comparable in the two groups. The time for temperature to fall by 1°C or 35°C and time to return to baseline was also comparable (P>0.05). No side effects related to body temperature were noted.

CONCLUSION

Both propofol and sevoflurane show similar effects in maintaining thermal homeostasis in patients undergoing transsphenoidal pituitary surgery.

Altered sympathetic thermoregulation in patients with hypothalamic dysfunction following resection of suprasellar tumors

In patients with suprasellar tumors, both the tumor and its surgical resection may produce hypothalamic dysfunction including thermoregulatory disturbances. We quantitated skin sympathetic nerve activity using microneurography in eight patients with hypothalamic dysfunction following resection. Skin sympathetic nerve activity, skin blood flow (by laser Doppler flowmetry), sweating, blood pressure, and pulse rate were monitored during changes of core (tympanic) temperature in the patients and seven healthy controls. Core temperature was decreased by 0.3 degrees C and increased by 0.5 degrees C relative to baseline using a cooling/heating blanket. The increase in sympathetic nerve activity in response to cooling did not differ between controls and patients (41.0+/-13.1 vs. 38.1+/-7.7 bursts [min degrees C](-1)), but an increase upon heating in controls (45.1+/-5.4 bursts [min degrees C](-1)) was absent in the patients (-26.0+/-17.5 bursts [(min degrees C](-1)). Skin blood flow during heating increased significantly in controls but not in patients (35.6+/-14.6 vs. 15.8+/-5.8 ml [min 100 g tissue degrees C](-1)). The patients thus showed impaired heat loss during body temperature elevation. Microneurography proved to be a sensitive measure of hypothalamic autonomic function.

Early and longtime modifications of temperature regulation after severe head injury. Prognostic implications

In summary, despite almost normal body temperatures in thermoneutrality, thermoregulatory characteristics in posttrauma patients are evidently altered and modified. These changes make the patients more susceptible to variations of the ambient temperatures and reduce their ability to counteract heat loads. They are more in danger of suffering heat stroke under external thermal load and during work or sport activities. In certain cases this could mean an important reduction of the daily quality of life.

Temperature regulation as possible prognostic indicator in patients with acute intracranial lesions

24 patients, 16 after severe head injury and 8 after spontaneous intracranial haematoma, were investigated by external cold load in order to determine their thermoregulatory capabilities. Tympanic temperature, several skin temperatures and oxygen consumption were measured. The patients where examined for SSEP and AEP. The cold induced thermoregulatory threshold temperature was determined by calculating the mean body temperature and by determining mean body temperature at which oxygen consumption increased due to the external cold load. In all patients core temperature and mean body temperature were significantly elevated by 1 degree C compared to controls. There was no difference of the course of the various body temperatures during cold load in the patient groups. In the trauma group 8 patients were able to increase oxygen use (VO2) during cold exposure, the other 8 patients showed no physiological thermoregulatory reaction. The heatproduction threshold temperature was increased by 1 degree C in the patient groups compared to controls. There was no significant correlation of AEP and SSEP findings to a preserved or disturbed thermoregulatory reaction. In the trauma patients, who were able to respond to a cold load, the outcome was significantly better (GOS = 3-5), than in those patients, who did not show a physiological increase of VO2 due to the cold load (GOS = 1-2). In conclusion, measurement of body temperatures alone is not sufficient to determine termoregulatory capacities. An examination using thermophysiological methods however provides more information about the function and structure damaged after severe head injury. An intact thermoregulatory systems seems to be correlated with a better prognosis after head injury.

Comparison of thermoregulatory characteristics of patients with intra- and suprasellar pituitary adenomas

Thermoregulatory capabilities under physiologic cold and heat exposure of 37 patients with suprasellar pituitary adenomas (As) and 10 patients with intrasellar adenomas (Ai) were analyzed and compared to each other and to 13 controls (Ctr.) In Ai no shift of the thermoregulatory threshold temperatures was observed. In As the regulation was shifted to a 0.5 degrees C higher mean body temperature in 82% of the patients, indicating a "set-point" elevation. The accuracy of the regulation against thermal loads was maintained, the velocity was reduced. Postoperative examination of As revealed a normalisation of the "set-point". Modifications of the hypothalamic amine systems by the compressive effect of the suprasellar adenomas are discussed to be the most probable cause for the observed thermoregulatory alterations.