The acute onset of nausea and vomiting following stereotactic radiosurgery: correlation with total dose to area postrema.

From 1986 to 1988, 44 patients have been treated for tumors or vascular lesions with stereotactic radiosurgery using a modified standard linear accelerator. In seven patients, nausea and vomiting occurred within 6 hours after the completion of radiosurgery. One of these patients with nausea and occasional vomiting pretreatment had exacerbation several hours after treatment, in spite of droperidol and prochlorperazine prophylaxis. Nausea and vomiting in the other six patients was self-limited and was completely resolved by 12 hours from onset. None of these six patients suffered from nausea and vomiting before treatment. This was directly correlated with the total dose to the vomiting center in the floor of the fourth ventricle (area postrema). The median dose to the vomiting center in the seven patients was 618 cGy (range 275-1257). The final patient in the series received 1088 cGy to the area postrema after droperidol and dexamethasone prophylaxis without developing nausea or vomiting. In the remaining 36 patients who received from less than 5 to 184 cGy to area postrema, nausea and vomiting did not occur. We recommend that patients treated with large fractions of radiation by radiosurgery in this area be premedicated appropriately.