Dorsal Midbrain Syndrome following Installation of Brachytherapy for Craniopharyngioma

Abstract

Objectives: To report an iatrogenic neuro-ophthalmologic complication of brachytherapy for craniopharyngioma. Methods: A case is described in which the injection of yttrium-90 into a suprasellar cyst resulted in permanent ocular motility disturbances. Results: A 39-year-old woman presented with headache, symptoms of hypophyseal dysfunction, and relative bitemporal hemianopia. Cerebral magnetic resonance imaging (MRI) disclosed a partially cystic suprasellar lesion. Removal of the solid mass and drainage of the cyst was performed, with pathologic confirmation of craniopharyngioma. The visual field defect resolved, but reappeared over three months due to enlargement of the cyst. An intracavitary stereotactic injection of yttrium-90 was then performed. After the procedure, the patient experienced headache with visual disturbances and the bitemporal hemianopic defect became absolute. Paralysis of conjugate upward saccades, convergence nystagmus, bilateral superior eyelid retraction, and loss of pupillary light reflexes (dorsal midbrain syndrome) also developed. MRI at this time showed contrast enhancement at the subependymal level of the aqueduct and at the inferior half of the fourth ventricle, suggesting a toxic-inflammatory process. After steroid treatment, her visual field improved, but the ocular motor disturbance remained unchanged. Over the next four months, an additional bilateral IVth nerve palsy ensued. Conclusions: Dorsal midbrain syndrome is a rare, but possible, side effect after intracavitary brachytherapy for craniopharyngiomas.