Pre-symptomatic local brain activity and functional connectivity alterations in nasopharyngeal carcinoma patients who developed radiation encephalopathy following radiotherapy

Radiation encephalopathy (RE) is a common complication in patients with nasopharyngeal carcinoma (NPC) who have received radiotherapy (RT), and recent neuroimaging studies have shown brain alterations in Post-RT patients prior to RE. However, whether there are functional alterations between those Post-RT patients who are proved to have RE in follow-up and those who do not develop it remains largely unknown. Here, we used resting state functional MRI to explore regional homogeneity (ReHo) and functional connectivity (FC) alterations in Post-RT patients with (Post-RT _{RE proved}; n = 18) or without (Post-RT _non-RE; n = 22) RE at follow-up, also making comparisons with a Pre-RT group (n = 23). Compared with the Pre-RT group, patients in Post-RT _non-RE and Post-RT _{RE proved} groups showed concurrent increased and decreased ReHo values in different brain regions inside and/or outside the radiation field, with the alterations in ReHo tending to increase if RE occurred. Seed-based FC analysis showed that compared with the Post-RT _non-RE group, patients in the Post-RT _{RE proved} group had different changing patterns of FC between a region of interest (ROI) in the right temporal lobe and distant brain regions (mainly in the sensorimotor system and default mode network). Receiver operating characteristic (ROC) curve analysis showed that the altered ReHo value in the ROI had excellent diagnostic performance for differentiating NPC patients who developed RE in follow-up from those who did not, with an area under the curve (AUC) value of 0.94. These ReHo and FC findings may provide new insights into the early diagnosis of RE.

Long-term recurrence and brain metastasis of nasopharyngeal carcinoma mimicking cystic radiation encephalopathy relapse: a case report

BACKGROUND

During medical imaging, cystic radiation encephalopathy and brain metastasis are difficult to differentiate, and hence they are easily misdiagnosed. To our knowledge, a nasopharyngeal carcinoma recurrence after more than seven years with cerebral metastasis that mimicked cystic radiation encephalopathy has not been reported.

CASE PRESENTATION

A 52-year-old man was admitted to the hospital owing to weakness of the right limb for one month, which increased in intensity for three days. He had been diagnosed with nasopharyngeal carcinoma in 2011, which was treated by radiotherapy. The patient successively developed cystic radiation encephalopathy and brain metastasis from the nasopharyngeal carcinoma, which mimicked cystic radiation encephalopathy relapse. Left frontotemporal craniotomy, surgical resection of brain metastasis, and repair of the skull base and dura were performed. Postoperative computed tomography showed that midline deviation recovered, and brain edema was reduced.

CONCLUSIONS

This report is significant because brain metastasis from nasopharyngeal carcinoma can masquerade as a benign entity and cause fatal consequences. In patients presenting with cystic radiation encephalopathy, brain metastasis should be considered as a differential diagnosis.