Bilateral paramedian thalamic syndrome after infection.

BACKGROUND: Although bilateral paramedian thalamic infarctions occur more frequently in adults than in children, they are rare entities at any age. The syndrome is thought to result from occlusion of the artery of Percheron, which arises as a common trunk from one of the posterior cerebral arteries to supply both paramedian thalamic regions. We describe two children with acute ischemic infarction involving both paramedian thalami developing after infection. PATIENTS: The first patient developed mutism with ataxia after chicken pox infection. The second child developed headache, somnolence, agitation, and speech dysfunction following an upper respiratory tract infection. Bilateral thalamic lesions were documented on magnetic resonance imaging of both children. CONCLUSION: Bilateral infarctions of the paramedian thalamus may result in severe illness and impairment. Common clinical manifestations include disorientation, confusion, hypersomnolence, deep coma and "coma vigil," or akinetic mutism (awake unresponsiveness), as well as severe memory impairment.

Dengue fever with unusual thalamic involvement.

Dengue is the most important mosquito-borne viral disease in the world and is caused by four distinct viruses (type 1 to 4) that are closely related antigenically. Infection by dengue virus may be asymptomatic or may lead to undifferentiated fever, dengue fever or dengue haemorrhagic fever. Recent observations indicate that the clinical profile of dengue is changing and the neurological complications are being reported more frequently. The neurological features includeheadache, seizures, neck stiffness, depressed sensorium, behavioural disorders, delirium, paralysis and cranial nerve palsies. Such neurological symptoms in dengue fever wereattributed to cerebral oedema, haemorrhage, haemoconcentration due to increasing vascular permeability, coagulopathy and release of toxic substances. Cerebral oedema, encephalitis-like changes (oedema and scattered focal lesions), intracranial haemorrhages as well as selective involvement of bilateral hippocampus in dengue infection have been reported previously on selective neuro-imaging but thalamic involvement is rare. We here report a case of a typical presentation of encephalopathy with left sided complete hemiplegia due to thalamic involvement in dengue infection.

Influenza A-associated encephalopathy with bilateral thalamic necrosis in Japan.

Two cases of acute encephalopathy in young children clearly showed evidence of influenza A virus infection and bilateral thalamic lesions. Influenza-associated encephalopathy with bilateral thalamic lesions has mostly been reported in Japan; it differs from Reye's syndrome in several respects. Other factors in addition to influenza virus infection may have contributed to the etiology of encephalopathy in our case patients.