Metaiodobenzylguanidine total-body scintigraphy required for revealing occult neuroblastoma in opsoclonus-myoclonus syndrome

A girl aged 13 months presented with clinical features of subacute progressive ataxia leading to abasia, astasia, loss of unsupported sitting and apraxia. In addition, an opsoclonus, myoclonia and introvert behaviour developed. MRI of the brain, EEG, extensive tests of blood, urine and CSF showed no abnormalities. Based on clinical symptoms only, the diagnosis of opsoclonus-myoclonus syndrome (OMS) could be made. Under the suspicion of a neuroblastoma, further investigations were performed: a lateral and antero-posterior X-ray examination of the chest showed no tumour; neither did ultrasound of the abdomen. Concentrations of catecholamines and their metabolites in 24 h urine were normal and none of five tested anti-neuronal antibodies were found. However, a total-body scintigraphy with [I¹²³] metaiodobenzylguanidine (MIBG) revealed a paravertebral hot spot on the left side compatible with a neural crest tumour. A MRI scan of the abdomen confirmed the supraphrenic lesion. [I¹²³]MIBG uptake was sufficient for [I¹³¹]MIBG therapy. The response of the tumour to this therapy was favourable. The neurological symptoms of the patient slightly improved under steroid treatment. Conclusion: Opsoclonus-myoclonus syndrome is a serious disease in infants, sometimes associated with occult neuroblastoma for which a full oncological work-up, including metaiodobenzylguanidine total-body scintigraphy is required.