A previously normal 6-month-old girl was seen for neuro-ophthalmic consultation for abnormal eye movements.
Torticollis to the right started 2 weeks previously, then head nodding began. Eye blinking then started, and the eyes were noticed to move side to side. Right foot and arm twitching were observed when she was sleeping. On examination, she fixed and followed with both eyes together. Ductions were full, but she had arrhythmic, chaotic, multidirectional random conjugate saccades. In addition, she had episodic blinking and head movements. There were no arm or leg movements.
Anterior segment was normal (pen light). The dilated fundus examination revealed normal discs and retinas.
What is your diagnosis and workup?
The abnormal eye movements were most consistent with opsoclonus. They were too irregular for nystagmus or spasmus nutans. The blinking and head movements were consistent with myoclonus. In half the cases of opsoclonus-myoclonus in children, the cause is either idiopathic or post-viral (cerebellitis). However, half may harbor an underlying neuroblastoma. In these cases the opsoclonusmyoclonus is caused by a remote, or paraneoplastic, effect of the cancer. Therefore, in suspected cases we recommend imaging of the head/neck/chest/abdomen/pelvis, urine vanillylmandelic acid (VMA), and homovanillic acid (HVA), as well as an metaiodobenzylguanidine (MIBG) scan.
The CT scan of the 6-month-old’s chest/abdomen/pelvis showed a soft tissue mass in the right paramedian aortocaval region which encased the right renal artery and caused mass effect on the inferior vena cava. The mass appeared distinct from the adrenal gland and was in the region of the parasympathetic chain.
MIBG scan confirmed the soft tissue mass in the region of the right adrenal gland. Spot urine HMA/VMA was unremarkable (the urine tests are sometimes normal when the neuroblastoma is relatively small).
The patient had an exploratory laparotomy for resection of the retroperitoneal mass. The tumor was located posterior and medial to the vena cava and behind the aorta. The histology showed poorly differentiated neuroblastoma with a low mitosis-karyorrhexis index, at this age consistent with International Neuroblastoma Pathology Classification favorable histology. Bone marrow biopsy, done for staging of possible metastatic disease, was negative.
The opsoclonus continued post-operatively, and therefore cycles of intravenous gammaglobulin (IVIG) and corticosteroid infusions were initiated. At her last exam six months post-operatively, there was no opsoclonus or myoclonus.
She will have surveillance scanning every six months until she is 5 years old.
In conclusion, this child had opsoclonus-myoclonus syndrome as a paraneoplastic effect of neuroblastoma.
Liu GT, Volpe NJ, Galetta SL. Neuro-ophthalmology: Diagnosis and Management. Second Edition. London, Elsevier, 2010.