Delayed radiation encephalopathy after radiotherapy for nasopharyngeal cancer: a CT study of 45 cases

Neurosurgery and prognosis in patients with radiation-induced brain injury after nasopharyngeal carcinoma radiotherapy: a follow-up study

Background

Radiotherapy is the standard radical treatment for nasopharyngeal carcinoma (NPC) and may cause radiation-induced brain injury (RI). Treatment for RI remains a challenge. We conducted this study to investigate the indications of neurosurgery, operation time and prognosis of patients with RI after NPC radiotherapy who underwent neurosurgical management.

Methods

This was a follow-up study between January 2005 and July 2011. Fifteen NPC cases of RI who underwent neurosurgery were collected. Brain Magnetic resonance imaging (MRI), surgery and histology were studied. The outcome was assessed by LENT/SOMA scales and modified Rankin scale.

Results

Brain lesion resection (86.7%) was more common than decompressive craniotomy (13.3%). According to LENT/SOMA scale before and six months after surgery, 13 of 15, 12 of 15, 14 of 15, and 14 of 15 cases showed improvement at subjective, objective, management and analytic domains, respectively. 12 of 15 patients showed improvement of modified Rankin scale after surgery. Three patients who underwent emergency surgery showed significant improvement (average score increment of 2, 2.7, 2.7, 3 and 2 at LENT/SOMA scale subjective, objective, management, analytic, and modified Rankin scale, respectively), as compared with 12 cases underwent elective surgery (average score increment of 1, 1, 1.4, 1.8 and 1 at LENT SOMA scale subjective, objective, management, analytic, and modified Rankin scale, respectively).

Conclusions

Neurosurgery, including brain necrotic tissue resection and decompressive craniotomy, improves the prognosis for RI patients, especially for those with indications of emergency surgery.

Radiation-induced necrosis deteriorating neurological symptoms and mimicking progression of brain metastasis after stereotactic-guided radiotherapy

PURPOSE

Although radiation-induced necrosis (RIN) is not a tumor in itself, the lesion progressively enlarges with mass effects and diffuse peritumoral edema in a way that resembles neoplasm. To identify the RIN that mimics progression of brain metastasis, we performed surgical resections of symptomatic RIN lesions.

MATERIALS AND METHODS

From June 2003 to December 2005, 7 patients received stereotactic-guided radiotherapy (SRT) for metastatic brain tumor, and they later underwent craniotomy and tumor resection due to the progressive mass effects and the peritumoral edema that caused focal neurological deficit. On MR imaging, a ring-like enhanced single lesion with massive peritumoral edema could not be distinguished from progression of brain metastasis.

RESULTS

Four patients had non-small cell lung cancer, 2 patients had colorectal cancer and 1 patient had renal cell carcinoma. The mean tumor volume was 8.7 ml (range: 3.0 approximately 20.7 ml). The prescribed dose of SRT was 30 Gy with 4 fractions for one patient, 18 Gy for two patients and 20 Gy for the other four patients. The four patients who received SRT with a dose of 20 Gy had RIN with or without microscopic residual tumor cells.

CONCLUSIONS

Early detection of recurrent disease after radiotherapy and identifying radiation-induced tissue damage are important for delivering adequate treatment. Therefore, specific diagnostic tools that can distinguish RIN from progression of metastatic brain tumor need to be developed.

Cerebral radionecrosis in patients with nasopharyngeal carcinoma

This study involved seven patients with cerebral radionecrosis following radiation therapy for nasopharyngeal carcinoma (NPC). Their charts were reviewed and the relationship of extracranial malignancies to cerebral radionecrosis was investigated. The radiation dose ranged from 70 to 135 Gy, and the latency was from 6 to 39 months. Two of seven patients died of NPC-related complications during follow-up. The crude incidence of cerebral radionecrosis in patients with NPC was 0.93% in our series. Improvement of symptoms could be achieved by corticosteroid therapy, with or without surgery. In a review of the literature, there were 306 cases of cerebral radionecrosis in extracranial malignancies. The nasopharynx is the most common primary site in cerebral radionecrosis of extracranial malignancies, followed by the scalp and sinonasal tract. The 3-year overall survival rate in our series was 68.57%, as provided by the Kaplan-Meier product limited method. Cerebral radionecrosis in NPC patients should be differentiated from tumor recurrence, in order to apply the appropriate treatment.

Potential usefulness of Tl-201 SPECT for differentiating radionecrosis in an irradiated nasopharyngeal carcinoma patient

Differentiation between cerebral radionecrosis and intracranial relapse in irradiated nasopharyngeal carcinoma (NPC) patients challenges the clinicians, especially when clinical manifestation and MRI findings are inconclusive. A 63-year-old NPC patient had intermittent dizziness and unsteady gait 3 years after irradiation. An ice water caloric test revealed absent response on the right ear, which was compatible with an enhanced lesion at the right temporal lobe on MRI scan. Furthermore, abnormal focally increased uptake over the anteriomedial aspect of the right temporal lobe was disclosed on 18-fluoro-2-deoxyglucose (FDG) positron emission tomography (PET), which suggested intracranial relapse. Conversely, serological study for Epstein-Barr viral titer was within normal limits, arguing against either recurrent or metastatic NPC. Hence, thallium (Tl)-201 single photon emission computed tomography (SPECT) was subsequently conducted, which failed to demonstrate abnormal thallium accumulation in the corresponding area. Accordingly, radiation necrosis of the temporal lobe rather than intracranial relapse is considered. The patient was rather well without locoregional recurrence or distant metastasis 2 years after presentation.

Postirradiation vertigo in nasopharyngeal carcinoma survivors

OBJECTIVE

Vertigo rarely manifested as an initial symptom of nasopharyngeal carcinoma or an early symptom after irradiation; however, increasing numbers of long-term nasopharyngeal carcinoma survivors experienced it. The purpose of this study was to investigate the causes of vertigo in irradiated nasopharyngeal carcinoma survivors.

SETTING

University hospital.

PATIENTS

From January 1992 to December 2001, a total of 113 nasopharyngeal carcinoma patients (67 men and 46 women) with postirradiation vertigo consecutively visited our vertigo clinic. The mean interval from completion of irradiation to the occurrence of vertigo was 10 years. Each patient underwent otoscopic examination and a battery of audiovestibular function tests. Then, correlation between the vertigo and the radiation effect was explored.

RESULTS

Postirradiation vertigo was mainly attributable to peripheral labyrinthine disorder (69%), followed by central vestibular lesions (31%). The vertiginous and associated symptoms including severity, nausea/vomiting, oscillopsia, or imbalance in cases of peripheral labyrinthine disorder were milder than those in central vestibular lesion. Meanwhile, the former had less life impact and better response to therapy compared with the latter. The mean radiation dosage in both groups was 73 +/- 6 Gy and 74 +/- 5 Gy, respectively, without a significant difference. Of these 113 patients, 85 patients (75%) had radiation otitis media in one or both ears, and 28 patients disclosed bilateral intact eardrums. The prevalence of radiation otitis media in patients with postirradiated vertigo was 53% versus 73% for those with radiation dosage less than or more than 71 Gy, respectively, exhibiting a significant difference. However, the prevalence of radiation otitis media is unrelated to radiation interval. In comparison with absent caloric responses in radiation otitis media ears, 32% versus 57% in those of less than or more than 71 Gy, respectively, indicates a significant difference.

CONCLUSIONS

Vertigo is a late complication in irradiated nasopharyngeal carcinoma survivors, which is mainly caused by the sequela of radiation otitis media. Because the latter is correlated with the radiation dosage, 70 Gy is recommended as the maximum dosage for nasopharyngeal carcinoma. Eradicating radiation otitis media in nasopharyngeal carcinoma survivors may subsequently prevent the postirradiation vertigo.

Late radiation necrosis of the brain: case report

We report a case of radiation necrosis occurring 47 years after resection and radiotherapy for a juvenile pilocystic cerebellar astrocytoma, the longest yet reported. The patient presented with progressive lower cranial nerve dysfunction, and eventually died from cardiopulmonary arrest secondary to aspiration. The presentation, diagnosis, pathological features, and management of radiation necrosis are discussed.