A Rare Event: Pituitary Apoplexy 6 Weeks After Gamma Knife Radiosurgery for a Non-Functioning Pituitary Macroadenoma

Abstract

Abstract Background: Pituitary apoplexy is a very uncommon side effect of gamma-knife radiosurgery, with only one other case to our knowledge. We report an acute presentation of pituitary apoplexy within 6 weeks of single fraction gamma-knife stereotactic radiosurgery for a non-functioning pituitary macroadenoma. Clinical Case: An 84-year-old male presented initially to his GP with lethargy. He was found to have a non-functioning pituitary macroadenoma 23Tx17APx12CC mm, with right cavernous sinus invasion causing cranial nerve IV palsy and panhypopituitarism. He declined transsphenoidal surgery. He was managed with pituitary hormone replacement therapy, including full anterior hormone replacement. Approximately 6 months after his initial diagnosis, he underwent single fraction stereotactic gamma knife radiosurgery aimed at local control. One month after single fraction gamma knife radiosurgery the patient presented to another hospital with a new two-day history of nausea, vomiting and persistent bilateral retro-orbital headache. On examination, he was afebrile and alert, with a new third nerve palsy of the right eye. The initial diagnosis was presumed steroid-underdosing by the non-treating team. An MRI of the brain and pituitary gland was performed. Review by the patient’s usual multidisciplinary pituitary care team confirmed acute pituitary apoplexy, with new haemorrhage on imaging in the gland post-gamma knife radiosurgery, with the additional clinical relevant development of a right cranial nerve III palsy. Review of the biochemistry showed to the patient to have a cortisol of <28nmol/L (despite Cortate ingestion), TSH <0.005mIU/L (RI: 0.40-5.00), T4 10.6 pmol/L (RI: 10.0-20.0) and T3 4.1 pmol/L (RI: 2.3-5.7). The patient was commenced on dexamethasone to aid reduction of swelling in the pituitary fossa, and there was resolution of the third nerve palsy. Pituitary apoplexy usually occurs spontaneously without any known precipitant. It has been reported to occur in association with other conditions including fractionated radiotherapy, head trauma, estrogen, anticoagulants1. Gamma knife radiosurgery is a form of stereotactic radiosurgery for intracerebral lesions, with lower overall dose and usually complications. Conclusion: To our knowledge, this is the second case of gamma-knife associated pituitary apoplexy. It raises the importance of recognising an acute clinical deterioration in our patients. References: 1. Briet C, Salenave S, Bonneville JF, Laws ER, Chanson P. Pituitary apoplexy. Endocrine reviews. 2015 Dec 1;36(6):622-45.