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Opsoclonus is a rare but distinctive disorder of ocular motility, characterised by irregular, continual, and conjugated chaotic saccades of the eyes. It is increased with eye closure and with fixation, and it persists during sleep. When accompanied by other symptoms of CNS involvement, such as head and appendicular myoclonus and truncal ataxia, it constitutes a striking clinical picture, known as opsoclonus-myoclonus syndrome. Opsoclonus is relatively frequent in children, but it is rare in adults. In adults, the most common aetiology is idiopathic, accounting for about 50% of cases; usually these patients are younger than 40 and have a good prognosis. The second most common cause is paraneoplastic, responsible for 20% of cases. All paraneoplastic cases reported in the literature occurred in patients over 40. The most common tumours, which give rise to 70% of described cases, are breast and lung cancers (small cell lung cancer and adenocarcinoma). Because of the nature of the underlying lesion, the great majority of these patients die in a few months.1 Whereas successful treatment of the malignancy results in a significant improvement in most children, the responses obtained in adults are rare.2 Up to now, only one patient with a kidney tumour—namely, a papillary tumour—and opsoclonus-myoclonus has been reported in the literature, and he did not benefit from removal of the tumour.3 We report a case of opsoclonus-myoclonus syndrome in a young adult patient with a renal cell tumour (RCC), who did not respond to medical therapy, but who dramatically improved after removal of the tumour.
He was a previously healthy 37 year old man who abruptly developed severe vertigo and gait unsteadiness. Subsequently, he developed chaotic eye movements, so severe that he could not open his eyes without vomiting. He could not even move his head without severe worsening of vertigo, eye movements, and nausea. He could neither stand nor walk because of ataxia and he complained of nervousness and emotional lability. Neurological examination disclosed coarse eye movements identifiable as opsoclonus. These movements, of variable amplitude, were present in a horizontal and, less often, in a vertical plane, without pauses between saccades, and greatly increased when attempting visual fixation in any direction. They persisted with eye closure and during sleep. At this acute stage opsoclonus was uninterrupted. Head and appendicular myoclonic jerks were induced by any attempt at truncal movements.
Laboratory tests, including complete blood count, routine chemistry, erythrocyte sedimentation rate, urinalysis, thyroid function and immunorheumatological tests were normal. His CSF was normal except for proteins, which were mildly increased (0.97 g/l); isoelectric focusing did not detect oligoclonal bands. Serum and CSF serological tests were negative for bacteria and different viruses (HIV 1–2; HVZ, CMV, HSV1+2: VCA, EBNA; adenovirus; parvovirus 19; Borrelia; Listeria). Brain MRI with and without gadolinium was normal. His EEG was diffusely slow. Thoracic CT was normal whereas abdominal ultrasound showed a 3.5 cm solid lesion, confirmed by abdominal MRI as a finely unhomogeneous mass, enhancing after gadolinium injection. Typical anti-onconeural antigen antibodies (anti-Hu, anti-Ri, and anti-Yo) were absent. A search for atypical antibodies was also performed by immunohistochemistry on rat brain serial cryostatic sections fixed by perfusion with 4% paraformaldehyde. The study was focused on the pons (paramedian pontine reticular formation and inferior olivary nuclei) and cerebellum (Purkinje cells and dentate nucleus), which are theoretically involved and that seem to be pathologically involved in inflammatory and degenerative processes in this eye movement disorder4; however no significant staining was found.
At the beginning of the symptomatology, treatment with clonazepam, thiamine, piracetam, and valproate, was started in an attempt to reduce neurological symptoms, without any benefit. Immunomodulators—namely, intravenous immunoglobulin (IVIg) (0.4 g/kg/day for 5 days) and prednisolone (50 mg/day)—were introduced after the diagnosis of the renal lesion and after the interruption of all previous drugs, but symptoms did not significantly improve. Ablation of the renal tumour was performed about 3 weeks after the beginning of the symptomatology. The cancer was a well differentiated RCC with a papillary differentiation (T1G1Nx); therefore the prognosis was excellent. In fact, tumour recurrence or diffusion at this stage of disease is very low, with a 5 year disease free survival rate of 100%.5The patient's serum did not stain cryostatic sections of his unfixed tumour. Just after removal of the tumour a slow but progressive improvement in the neurological symptoms started, beginning with an amelioration of opsoclonus, vertigo, and nausea. Eye movements became less frequent with pauses between each saccade becoming longer and longer, to disappear completely after 3 months. Some days after the intervention the patient began to eat and to spend a large part of the day with his eyes open. This progress allowed him to start physiotherapy. Six months after surgery the patient was completely normal and attending to his usual tasks.
This is the first report of an association between opsoclonus-myoclonus and renal cell tumour. We suggest that the presence of a kidney tumour must be taken into consideration every time an opsoclonus-myoclonus syndrome is seen, even in a young adult. This is essential as the early detection of such a tumour permits the removal of the mass in a very early phase, giving rise to a cure. Moreover, in our patient the surgical treatment resulted in the disappearance of the neurological symptoms, which had neither responded to strong immunosuppressive nor to any symptomatic medical therapy.
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