J Neurol (2011) 258:1098–1104 Fig. 3 47-year-old man who was treated 5 years previously for a left c parietal oligodendrolioma with chemo- and radiation therapy, now presenting with right hemianopia and mild paresis of his right arm and leg. T2 weighted FLAIR MR images a showing gyral swelling and signal increase in the temporal lobe. b After gadolinium administra- tion, diffuse gyral enhancement is seen in the occipital, temporal and insular lobe. Proton density (c) and T1 post gadolinium (d) MR imaging 8 days later showing normalization of signal intensity in the temporal lobe and marked reduction in abnormal gyral enhancement. After 3 years, the patient presented again with right sided paresis. MR imaging again shows signal increase in the temporal lobe on PD weighted images (e) while on T1 post gadolinium imaging (f) abnor- mal gyral enhancement is again visible. Like after the previous episode, the MR abnormalities disappeared (g, h) astrocytoma. The tumour was resected and he subsequently had focal brain radiation (50 Gy in 20 fractions). In the following 5 years he had infrequent focal seizures of the left arm but no tumour recurrence was observed on repe- ated MRI. Five years after initial treatment, however, he developed a progressive clumsy left hand, left-sided facial paresis and dysarthria in combination with an increase of focal seizures. An EEG showed nearly continuous epileptic discharges diffusely over the right hemisphere. He was treated with intravenous clonazepam and valproate. The MRI demonstrated no tumour recurrence but a gyriform enhancement and swelling of the right parieto-temporal cortex (Fig. 4a–f). CSF examination was, besides a slightly elevated protein level, completely normal (Table 1). Over the following weeks the focal seizures disappeared and the left sided weakness improved. The patient was discharged from hos- pital on valproate and nearly complete resolution of the clinical picture. The abnormalities on MRI did partially resolve (Fig. 4g, h). Three months later, a new MRI was suggestive for recurrent tumour in the right temporal lobe, showing several nodular enhancements. A biopsy conﬁrmed recurrent high-grade glioma, for which he was treated with temozolomide. Following chemotherapy treatment, the abnormal gyral and leptomeningeal enhancement tempo- rarily disappeared, but recurred for which PCV chemo- therapy was started. Again, a complete response ensued. Ten years after the initial diagnosis of anaplastic astrocytoma he developed left hemianopia and a clumsy left hand, but had no seizures. On MRI a right occipital contrast enhancing tumour was found, suggestive for recurrent tumour. Resec- tion was planned, but pre-operative imaging showed the lesion to be smaller and an open biopsy did not conﬁrm active tumour growth. Postoperatively he suffered from very frequent focal seizures of the left side of his face and a clumsy left hand, which did not subside until he was put into a propofol induced coma. He completely recovered within several weeks. Follow-up MRI demonstrated the occipital contrast-enhancing to have disappeared completely (Fig. 4i–l). The patient died a year later from tumour recurrence, 11 years after the initial diagnosis. 1101 Discussion All four patients had (partly) reversible neurological symptoms as well as reversible imaging ﬁndings several years after radiation therapy for their brain tumours. The 123