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Palatal myoclonus in postinfectious opsoclonus myoclonus syndrome : a case report.
Correspondence Address:
An adult male presenting with acute onset opsoclonus, myoclonus and cerebellar ataxia is being reported. Patient had myoclonus involving limbs and palate. There are only a few reported cases associated with palatal myoclonus. Patient showed gradual spontaneous recovery. Possibility of underlying malignancy was excluded by detailed investigations.
A clinically benign syndrome of opsoclonus myoclonus presumably of postviral infectious nature has been well described.[1],[2] This disorder occurs after a prodromal illness including gastrointestinal tract symptoms (56%), upper respiratory tract symptoms (18%) and fever (26%).[3] Most of the patients recover within a few months. A second setting in which opsoclonus myoclonus occurs in adults is a paraneoplastic process. Generally there is no prodromal illness. As one might expect, because of nature of underlying disease, survival is shorter. Although there are many reported cases of opsoclonus myoclonus in children, there is no large series of cases in adults.
A 58 years old male had mild febrile illness of five days duration with loose motions. Three days later he developed sudden onset tremulousness of body and chaotic eye movements which persisted even during sleep. Patient had history of anorexia and weight loss of about 25% as compared to his premorbid status. He was non smoker. Neurological examination revealed a conscious and well oriented person. Speech was normal. Chaotic burst of conjugate eye movements were present in all meridians, increasing on eye movements and attempt to fix gaze. There were myoclonic jerks involving limbs. Palatal myoclonus was also noticed. He could not stand or sit unsupported because of truncal ataxia and titubation. Mild dysmetria, dyssynergia, dysdiadochokinesia were present. Motor system examination showed cogwheel rigidity and brisk reflexes. Plantars were flexor. There was no sensory involvement. Palmomental reflex was positive bilaterally. Investigations including haemogram, platelet count, reticulocyte count, peripheral blood film, packed cell volume examination were normal. ESR was 40 mm in 1 hr. Urine examination was normal. Biochemistry including serum electrolytes, renal function tests, liver function tests, blood sugar, alkaline phosphatase were normal. CSF showed no cells, proteins 20 mg%, sugar 48mg% (corresponding blood sugar : 108mg%). CSF flow- cytometry showed few lymphocytes, but no malignant cells. Microscopic examination and culture of stool were normal. MRI brain did not reveal any abnormality [Figure 1]. Further investigations were done to exclude malignancy. X-Ray chest was normal. CT chest [Figure 2] and abdomen were normal except one benign cyst in liver and one in right Kidney.
Opsoclonus, a disorder of saccadic stability, consists of involuntary arrhythmic multidirectional high amplitude conjugate saccades. Opsoclonus is often associated with diffuse or focal myoclonus and truncal titubation with or without other cerebellar signs. It occurs primarily in children, as a self limited illness and probably the result of viral infection of brainstem. This disorder also occurs as a paraneoplastic syndrome in as many as 2% of children suffering from neuroblastoma. Anderson et al reviewed 19 adult cases, out of which 9 had undifferentiated or small cell lung carcinoma.[4] The other underlying tumours were adenocarcinoma of the lung, epidermoid carcinoma of the lung, tumours of breast, uterus, bladder, thyroid, bone and fallopian tube. Neurological symptoms preceded diagnosis of tumour by up to 1 year in 12 patients and in many of these, recognition of neurological disorder led to detection of tumour. Opsoclonus myoclonus also occurs in association with intracranial tumours, hydrocephalus, thalamic haemorrhage and multiple sclerosis. Digre reviewed 58 cases of opsoclonus in adults.[3] It was reported most frequently as a sequelae to a presumed viral infection. There were 34 patients with a constellation known as myoclonic encephalopathy. Infection was documented only in 8 cases. These included psittacosis, rikettsia, coxsackie virus B3 and B2. Twenty eight (82%) of 34 cases resolved without sequelae in about eight weeks. In the group suspected of having infectious origin, only 6 out of 38 had definite proof of coxsackie B3 infection.[5] Pauranik et al described six cases of acute onset opsoclonus myoclonus following a febrile episode.[6] Four out of six patients showed evidence of rubella infection. Bhatt et al described an acute syndrome of ocular oscillations and truncal myoclonus, following recent infection in a 25 years old male.[7] Post infectious opsoclonus with palatal myoclonus has been reported in one and half year girl by Sridharan et al.[8] The present case presented with history of fever and loose motions (probably viral in origin) developed opsoclonus myoclonus and ataxia. In addition he had cogwheel rigidity and brisk reflexes. Possibility of postinfectious aetiology was considered in view of the preceding fever and diarrhoeal illness and negative work up for malignancy. However, there are only few cases mentioned in the literature who had associated palatal myoclonus. Cooper reported 4 cases of eye movements associated with myoclonus.[9] Out of four, three were associated with palatal myoclonus. Boddie reported one case of opsoclonus, ocular bobbing with palatal myoclonus.[10] In both reports aetiology was vascular. The case under discussion had postinfectious palatal myoclonus, thus having a rare presentation. Anatomical localisation of opsoclonus myoclonus is not clear. Autopsy data has suggested loss of Purkinje cells, or dentate demyelination. Brainstem and cerebellum together have also been implicated. Three different premotor neurons, burst, tonic and pause cells, located in pontine reticular formation ultimately control the eye movements. Tonic cells hold the eye in new position. Burst cells initiate in involvement of saccades and pause cells inhibit burst cells. Disease of burst cells produces abnormal saccades. Disease of pause cells produce abnormal oscillation like flutter or opsoclonus. Lesion in dentatorubral pathway may be responsible for opsoclonus and myoclonus of limbs and palate. Immune mechanisms have been suspected with evidence of inflammatory cells in perivascular areas, quantitative abnormalities of IgG and abnormal lymphocyte proliferation. It is hoped that discovery of anti-purkinje cell antibodies in opsoclonus will supply additional localisation and pathophysiology of opsoclonus. Takamichi et al demonstrated positive lesion in opsoclonus myoclonus syndrome by MRI.[11] Treatment for opsoclonus myoclonus, due to any cause, has not been uniformly successful. Many authors recommended ACTH or steroid. Others suggest no treatment in cases associated with presumed viral illness, since symptoms abate in 6-8 weeks without therapy. There are reports of baclofen, clonazepam, propanolol, thiamine, thyrotropin releasing hormone, 5HT, chloramphenicol and valproic acid reducing eye movements. However, there is no single agreement on treatment. The underlying cause needs to be treated (e.g. tumour, stroke etc.). Our patient improved by 50% within 2" months, although for symptomatic benefit, he was treated with tab. clonazepam 0.5mg three times a day. In cases of post infectious opsoclonus myoclonus syndrome patient should be thoroughly investigated for detection of cause and to exclude paraneoplastic process. Recovery occurs in most of the cases without any sequelae.
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