Infantile bilateral striatal necrosis: chronic and acute manifestations in a single case

Acute encephalopathy associated with influenza and other viral infections

Acute encephalopathy is the most serious complication of pediatric viral infections, such as influenza and exanthem subitum. It occurs worldwide, but is most prevalent in East Asia, and every year several hundreds of Japanese children are affected by influenza-associated encephalopathy. Mortality has recently declined, but is still high. Many survivors are left with motor and intellectual disabilities, and some with epilepsy. This article reviews various syndromes of acute encephalopathy by classifying them into three major categories. The first group caused by metabolic derangement consists of various inherited metabolic disorders and the classical Reye syndrome. Salicylate is a risk factor of the latter condition. The second group, characterized by a systemic cytokine storm and vasogenic brain edema, includes Reye-like syndrome, hemorrhagic shock and encephalopathy syndrome, and acute necrotizing encephalopathy. Non-steroidal anti-inflammatory drugs, such as diclofenac sodium and mephenamic acid, may aggravate these syndromes. Severe cases are complicated by multiple organ failure and disseminated intravascular coagulation. Mortality is high, although methylprednisolone pulse therapy may be beneficial in some cases. The third group, characterized by localized edema of the cerebral cortex, has recently been termed acute encephalopathy with febrile convulsive status epilepticus, and includes hemiconvulsion-hemiplegia syndrome and acute infantile encephalopathy predominantly affecting the frontal lobes. Theophylline is a risk factor of these syndromes. The pathogenesis is yet to be clarified, but an increasing body of evidence points to excitotoxicity and delayed neuronal death.

Transient seizure disappearance due to bilateral striatal necrosis in a patient with intractable epilepsy

An 8-year-old girl had suffered from intractable epilepsy due to cortical dysplasia. She developed mycoplasma pneumonia with massive pleural effusion. Fever continued for 3 weeks. Four weeks after the onset of this infection, she suddenly developed horizontal nystagmus, ataxia, choreoathetotic movements and confusion. CT disclosed swelling and low density of the heads of the caudate nuclei and putamina bilaterally. MRI revealed areas of symmetrical high intensity in the striatum on T2-weighted imaging. These lesions were thought to comprise bilateral striatal necrosis (BSN) mediated by the mycoplasma infection or Wernicke encephalopathy. Six months later, she had completely recovered clinically. During the 6 months after BSN, she did not have any epileptic seizures. Her epileptic seizures reappeared thereafter at a lower frequency. The striatum may be involved in the propagation pathway for epileptic seizure activity in this patient.

Acute necrotizing encephalopathy of childhood: a novel form of acute encephalopathy prevalent in Japan and Taiwan

The clinical, radiological and pathological features of acute necrotizing encephalopathy of childhood, a disease entity established recently, are described. This disease predominantly affects infants and young children living in Japan and Taiwan, and manifests itself as acute encephalopathy following viral infections. The hallmark of this encephalopathy is multifocal, symmetric brain lesions affecting the bilateral thalamus, brainstem tegmentum, cerebral periventricular white matter and cerebellar medulla, which can be visualized by computed tomography and magnetic resonance imaging. Both the gray and white matter are involved, with neuropathological evidence of local breakdown of the blood-brain barrier (dysoria). The prognosis was poor in the 1980s, but has improved recently. A characteristic combination of focal neurologic signs is often recognized as the sequelae. Its distinction from clinically similar conditions, such as the Reye syndrome, and from pathologically related conditions, such as the Leigh and Wernicke encephalopathies, is also discussed.

Movement disorders in childhood organic acidurias. Clinical, neuroimaging, and biochemical correlations

Over the last 5 years the Pediatric Neurology service at King Faisal Specialist Hospital and Research Centre (KFSH&RC) has seen 131 infants and children with movement disorders. Forty-nine (37%) had identifiable biochemical defects, 25 of which were organic acidemias. Nineteen of 29 patients with dystonia had organic acidemias, primarily glutaric aciduria type 1 (7 patients), bilateral striatal necrosis (4 patients), and 3-methyl glutaconic aciduria (3 patients). All patients with parkinsonian rigidity (n = 11) had organic acidemias; again, the greatest number accounted for by glutaric aciduria type 1 (7 patients), who had both parkinsonian rigidity combined with dystonia. Myoclonus occurred in only 1 of 25 and chorea in 7 of 25 patients with organic acidemias. At the least all patients had bilateral lesions of putamen and head of caudate, seen best in MRI brain scans as increased T2 signal intensities with normal volume, and later with volume loss.