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INTRODUCTION Opsoclonus myoclonus syndrome (OMS) is an inflammatory neurological disorder, which is characterized by chaotic uncontrolled movements of the eyes and involuntary jerk-like movements of the body caused by contractions of a group of muscles. It was described first by Marcel Kinsbourne in 1962. It is also known as “dancing eyes–dancing feet,” “Kinsbourne syndrome,” “myoclonic encephalopathy,” or “opsoclonic encephalopathy.” It is associated with ocular, motor, behavioral, sleep, and language disturbances. OMS may be associated with an occult body tumor or infections or it may be idiopathic in nature. We report a case of OMS along with dengue infection. Although dengue can present with some neurological manifestations such as meningoencephalitis, transverse myelitis, or along with Guillain–Barre syndrome (GBS), it is very rare to find OMS associated with dengue.

INTRODUCTION Opsoclonus myoclonus syndrome (OMS) is an inflammatory neurological disorder, which is characterized by chaotic uncontrolled movements of the eyes and involuntary jerk-like movements of the body caused by contractions of a group of muscles. It was described first by Marcel Kinsbourne in 1962. It is also known as “dancing eyes–dancing feet,” “Kinsbourne syndrome,” “myoclonic encephalopathy,” or “opsoclonic encephalopathy.” It is associated with ocular, motor, behavioral, sleep, and language disturbances. OMS may be associated with an occult body tumor or infections or it may be idiopathic in nature. We report a case of OMS along with dengue infection. Although dengue can present with some neurological manifestations such as meningoencephalitis, transverse myelitis, or along with Guillain–Barre syndrome (GBS), it is very rare to find OMS associated with dengue. CASE HISTORY A 14-year-old boy presented with high-grade fever accompanied with headache, arthralgia, and myalgia for 4 days. No associated shortness of breath, cough, urinary disturbance, or ear discharge was reported. On the 4th day, he started having abnormal movement in his eyes and arms, with imbalance while walking or sitting without support. On neurological exam, he was oriented to self, relatives, and place but disoriented to time. On extraocular eye movement examination, bilateral, involuntary, chaotic, multidirectional eye movements were noted. Rest of the cranial nerve examination was normal. His motor exam revealed appendicular as well as truncal myoclonus along with severe symmetric ataxia of trunk, gait, and limbs. Sensory exam and deep tendon reflexes were normal. He had neck rigidity and positive Kernig’s sign. His hemogram revealed thrombocytopenia with a platelet count of 50000/mm3 with normal values for all other blood cells. His renal functions, liver functions, electrolytes, urine analysis, peripheral smear for malaria, blood and urine culture, and X-ray chest were normal. IgG and IgM antibody for dengue virus and NS1 antigen specific for dengue infection were positive. In the presence of fever, thrombocytopenia, and positive dengue seromarkers, a diagnosis of dengue was made. However, as dengue is not commonly known to cause these neurologic abnormalities, further workup was carried out. Magnetic resonance imaging (MRI) of the brain with contrast was normal. Cerebrospinal fluid (CSF) examination revealed 25 cells with lymphocytic pleocytosis with 68mg/dL protein and normal glucose. Over the next 4–5 days, he was given supportive management with intravenous fluids and paracetamol. Subsequent hemogram showed gradually recovering thrombocytopenia. He became afebrile after 5 days of hospitalization and his platelets improved to 270,000/mm3. His opsoclonus, myoclonus and ataxia improved spontaneously and he did not require any immunomodulation or symptomatic treatment.

venous fluids and paracetamol. Subsequent hemogram showed gradually recovering thrombocytopenia. He became afebrile after 5 days of hospitalization and his platelets improved to 270,000/mm3. His opsoclonus, myoclonus and ataxia improved spontaneously and he did not require any immunomodulation or symptomatic treatment. DISCUSSION Dengue is a mosquito-borne viral disease caused by dengue virus, which belongs to Flaviviridae family, having four closely related but antigenically different serotypes: DENV1, DENV2, DENV3, and DENV4.[12] Serotypes commonly associated with neurological manifestations are DENV1 and DENV2[345]. DENV4 was also detected in the immunochemistry of CSF of a patient with encephalitis.[6] Dengue is endemic in almost all tropical and subtropical regions and is the second most common mosquito-borne disease globally.[1] Dengue can manifest itself in varied presentations including asymptomatic state, dengue fever, dengue hemorrhagic fever, and dengue shock syndrome; it may rarely cause neurological manifestations. Neurological manifestations associated with dengue include encephalitis, myelitis, meningitis, GBS, Miller Fisher syndrome, neuromyelitis optica, and optic neuritis.[7] In a study conducted in Lucknow, Uttar Pradesh, India, several neurological manifestations have been described in association with dengue infection. OMS was found in only two cases in that series of patients.

e encephalitis, myelitis, meningitis, GBS, Miller Fisher syndrome, neuromyelitis optica, and optic neuritis.[7] In a study conducted in Lucknow, Uttar Pradesh, India, several neurological manifestations have been described in association with dengue infection. OMS was found in only two cases in that series of patients. Our case was a child with confirmed dengue infection who developed opsoclonus–myoclonus–ataxia. We had ruled out other causes for opsoclonus–myoclonus–ataxia by performing an MRI, which was unrevealing, and no history of malignancy was reported with his opsoclonus–myoclonic movements, which resolved spontaneously over a week. Although his opsoclonus and myoclonic movements occurred a few days after the onset of his fever suggesting a postinfectious immune injury, CSF pleocytosis may suggest dengue encephalitis.

aling, and no history of malignancy was reported with his opsoclonus–myoclonic movements, which resolved spontaneously over a week. Although his opsoclonus and myoclonic movements occurred a few days after the onset of his fever suggesting a postinfectious immune injury, CSF pleocytosis may suggest dengue encephalitis. Neurological complications in dengue infection have been hypothesized through three pathogenic mechanisms: neurotropism, systemic complications, or postinfectious immune-mediated mechanism or antibody-dependent enhancement. It is likely that the OMS could be secondary to both encephalitis and postinfectious immune injury. Once a host is infected with dengue infection, the infection provides lifelong immunity to the same subtype but no protection against the other three subtypes. This phenomenon is called antibody-dependent enhancement. The antibodies form complexes with the virus and infect mononuclear phagocytes, which consequently result in the infection of higher number of host cells, thus improving viral replication and worsening clinical signs, which may lead to neurological manifestations of dengue infection.

led antibody-dependent enhancement. The antibodies form complexes with the virus and infect mononuclear phagocytes, which consequently result in the infection of higher number of host cells, thus improving viral replication and worsening clinical signs, which may lead to neurological manifestations of dengue infection. OMS is usually recognized as a manifestation of neuroblastoma in children[8] and paraneoplastic syndrome in adults.[9] Increasing evidence that OMS can occur as a manifestation of bacterial or viral infections such as coxsackievirus, Epstein–Barr virus, adenovirus, herpes virus, influenza virus, human immunodeficiency virus (HIV), as well as post-streptococcal or mycoplasma infection is available.[10] OMS is rarely seen as a manifestation of dengue. Table 1[21] enlists cases in medical literature describing OMS in parainfectious settings. To the best of our knowledge, OMS has only been reported in three cases with dengue infection (two adults and a child).[511] Of the two adults, presence of NS1 or IgG seroconversion was not determined in one of the cases, whereas in the child, MRI and CSF were not performed to exclude other causes. Table 1 List of patients described in current medical literature to have developed OMS

OMS is usually recognized as a manifestation of neuroblastoma in children[8] and paraneoplastic syndrome in adults.[9] Increasing evidence that OMS can occur as a manifestation of bacterial or viral infections such as coxsackievirus, Epstein–Barr virus, adenovirus, herpes virus, influenza virus, human immunodeficiency virus (HIV), as well as post-streptococcal or mycoplasma infection is available.[10] OMS is rarely seen as a manifestation of dengue. Table 1[21] enlists cases in medical literature describing OMS in parainfectious settings. To the best of our knowledge, OMS has only been reported in three cases with dengue infection (two adults and a child).[511] Of the two adults, presence of NS1 or IgG seroconversion was not determined in one of the cases, whereas in the child, MRI and CSF were not performed to exclude other causes. Table 1 List of patients described in current medical literature to have developed OMS Sr. no. Child/adult Infection Treatment Prognosis/result Reference 1. Adult Streptococcal infection Oral steroids Streptococcal infection with OMS Dassan et al. [12] 2. Adult Lyme disease Antibiotics Lyme disease with OMS Peter et al.[13] 3. Child Parainfluenza type 3 Parainfluenza type 3 with OMS McCarthy et al.[14] 4. Child Coxsackie B3 infection Spontaneously Coxsackie B3 infection with OMS Kuban et al.[15] 5. Child Adenovirus Adenovirus with OMS Syrbe et al.[16] 6. Child Herpesvirus 6 Herpesvirus 6 with OMS Naselli et al.[17] 7. Adult Mumps virus Intravenous immunoglobulin Mumps virus with OMS Kang and Kim[18] 8. Adult West Nile virus West Nile virus with OMS Bîrluţiu and Bîrluţiu[19] 9. Adult Influenza A Intravenous immunoglobulin and corticosteroids Influenza A with OMS Morita et al.[20] 10. Child Hepatitis C Hepatitis C with OMS Ertekin and Tan[21] Different modalities of treatment have been described in medical literature to treat OMS. In patients with OMS in the setting of infection, along with treatment of infection, immunomodulatory treatment with either steroids or intravenous immunoglobulin has been considered. Symptomatic treatment with clonazepam has also been advocated. However, the treatment in most cases is empiric and no evidence-based guideline or consensus is available currently. In our case, OMS with dengue resolved spontaneously without any other form of treatment and by simply giving medication for the symptoms of dengue.

atic treatment with clonazepam has also been advocated. However, the treatment in most cases is empiric and no evidence-based guideline or consensus is available currently. In our case, OMS with dengue resolved spontaneously without any other form of treatment and by simply giving medication for the symptoms of dengue. Our case is unique in that it has features of both direct neurotropic and immune-mediated damage, and it improved spontaneously without any immunomodulatory treatment. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.