MR imaging of neonatal brain infections

Infections of the brain in the postnatal period differ from those in older children as a result of a combination of distinct epidemiologic factors in general, and immaturity of neonatal brain and immunologic host response in particular. It has been recognized that clinical and neurologic signs are often nonspecific, sometimes scarce, and seldom correlate with the extent of neuroimaging findings, thus warranting an early MR imaging examination in the course of the disease, enabling rapid therapy institution and better clinical outcome. This article reviews most of postnatal pathogen agents involved in neonatal brain infections, related physiopathology, and neuroimaging findings.

Aicardi syndrome mimicking intrauterine hydrocephalus

Congenital enlargement of the cerebral ventricles is now commonly recognized in utero due to the availability of high resolution prenatal ultrasonography. It is important to distinguish between congenital hydrocephalus and ventricular enlargement due to malformations, infections or other destructive processes because these disorders can have markedly different prognoses. We report an infant diagnosed with Aicardi syndrome in the newborn period based on brain MRI and ophthalmological findings after she was referred for evaluation of hydrocephalus seen on fetal ultrasound. Aicardi syndrome most commonly comes to medical attention because of seizures later in infancy.

Central nervous system infections in the pediatric population

Central nervous system infections and sequelae in the pediatric population may present differently depending on the patient's stage of development. Infections contracted from conception through the neonatal period may affect central nervous system formation, whereas infections acquired later tend to cause parenchymal destruction. This article discusses congenital, focal parenchymal, extra-axial, and diffuse parenchymal infections and their effect on the developing brain.

Activation of the innate immune system in murine congenital Toxoplasma encephalitis

A murine model of congenital Toxoplasma encephalitis (CTE) was established in NMRI mice following prenatal infection with a low dose of Toxoplasma gondii (DX strain). Histopathologically, the disease exhibited the key features of human CTE including foci of necrosis, intracerebral calcifications, and ventriculitis. The inflammatory response in the brain of infected animals was predominantly mediated by macrophages and granulocytes with additional participation of astrocytes. These findings indicate that the prenatal Toxoplasma infection closely parallels human CTE, but differs significantly from adult toxoplasmosis.

An unusual CT presentation of congenital cerebral toxoplasmosis in an 8 month-old boy with AIDS

We report on a 8-month-old boy with AIDS, born of an asymptomatic mother with positive HTLV-III serology. He was hospitalized in the Intensive Care Unit because of anemia, fever and hepatosplenomegaly. Chest X-ray showed pneumonia and subsequent blood cultures were positive for Candida albicans. After 3 days of Amphotericin B treatment, the patient was transferred to Infectious Disease Department. After 30 days of hospitalization, the patient developed a rapid neurological impairment evolving into coma. CT scan showed a round, ring-shaped low density lesion with hyperdense and enhancing haemorrhagic centre in the left basal ganglia and a smaller hypodense lesion on the right. There was also evidence of cortical atrophy and mild ventricular dilatation. Such lesions are more commonly described in children with AIDS and congenital cytomegalic inclusion virus (CMV) encephalitis. In this case toxoplasma cysts were shown microscopically reinforcing the contention that in patients with AIDS, toxoplasma gondii infection may occur with atypical manifestation.

Cytomegalovirus encephalopathy in an infant with congenital acquired immuno-deficiency syndrome

A female infant born pre-term to a HIV seropositive mother presented at birth with seropositivity for HIV and CMV viruria. At five months of age she developed an AIDS-related complex. Six months later she died from rapidly progressive diffuse encephalopathy. Post mortem examination revealed generalized CMV infection. Neuropathological examination showed a nodular encephalitis with occasional cytomegalic cells containing characteristic CMV inclusion bodies. There was no evidence of HIV encephalitis; immunostaining for HIV antigen (gp 41) was negative. Opportunistic infections in infants with congenital AIDS are the exception. To our knowledge, only one case of CMV encephalitis in an infant with congenital AIDS has been reported previously. In that case, as in the present one, a reactivation of a congenital CMV infection is likely.

Echogenic vasculature in the basal ganglia of neonates: a sonographic sign of vasculopathy

The vessels that supply the basal ganglia and thalami are not normally conspicuous on the cranial sonograms of neonates. Twelve neonates with abnormally echogenic or "bright" vessels on cranial sonograms were studied. Records of these 12 patients were reviewed and were correlated with the neuropathologic findings available in four. The clinical diagnoses were cytomegalovirus infection (five patients), rubella (two patients), congenital syphilis (one patient), and trisomy 13 syndrome (three patients). No diagnosis was made in one infant. At neuropathologic examination, perforating medium-sized arteries to the basal ganglia and thalami had thickened hypercellular walls, with deposits of amorphous basophilic material in three infants. Results of computed tomography and radiography of brain sections were normal in these areas. Sonography is helpful in detecting early noncalcific inflammation and mineralization in vasculitis. Although nonspecific, these findings should alert the physician to the possibility of congenital infection or chromosomal abnormality.

The evolution of neonatal herpes encephalitis as demonstrated by cranial ultrasound with CT correlation

Three neonates with herpes encephalitis had serial cranial ultrasound and CT studies performed during their hospitalization. Initially, subtle changes of diffuse brain edema were present but with no ventricular compression. A second phase revealed progressive brain edema with ventricular compression. A third phase with enlarging ventricles indicates developing encephalomalacia. Occasionally cyst formation may be noted within the cerebral white matter, a phenomenon initially more readily evident by ultrasound.

Liquefactive necrosis in Coxsackie B encephalitis

Coxsackieviruses may cause serious illness in infants and children, specifically myocarditis and meningoencephalitis. Central nervous system lesions have been characterized as inflammatory in nature with mononuclear cell infiltration, neuronophagia, and glial nodule formation largely confined to the brain stem and spinal cord. We present two infants with documented Coxsackie B virus infection who also had widespread multifocal areas of liquefaction necrosis unassociated with inflammation. Such areas of bland necrosis, especially in the cerebrum, are unusual in Coxsackie B virus infection, and may provide the morphological substratum of permanent neurologic impairment in children who survive.

Herpes zoster in a 2-week-old premature infant with possible congenital varicella encephalitis

This report concerns a case of neonatal herpes zoster associated with maternal gestational varicella. The child developed skin lesions at 18 days of age virologically confirmed to be varicella-zoster. The baby also had encephalitis and aspiration probably due to bulbar paralysis. Multiple small necrotic areas were found in the thalamus at post-mortem examination.

Herpes simplex encephalitis

This is an acute necrotizing encephalitis with a high mortality rate. It is thought to occur by the reactivation of herpes simplex virus type 1 from latently infected trigeminal ganglia, with subsequent centripetal spread and fulminant growth in tissue of the central nervous system. Prompt diagnosis and antiviral therapy are required because of the rapidly progressive nature and severe consequences of this disease. The physician must understand the pathophysiology to fully appreciate the need for early diagnosis and the gravity of mismanagement.

Rubella virus and its effects on the central nervous system

Rubella virus appears to have few rivals in the variety of its pathologic expressions in man. The authors explore some of these, address the virus's ability to establish persistent infections, discuss the introduction of an effective vaccine for rubella, and touch on future research into rubella virus.

Neonatal herpes simplex infection in the absence of mucocutaneous lesions

Six infants with disseminated HSV had no mucocutaneous lesions at any time during the course of the illness. These infants presented with lethargy, poor feeding, apnea, acidosis, and hepatomegaly. The diagnosis of HSV was made by culturing the infant's oropharynx and blood, and the maternal cervix. Eight infants with HSV encephalitis had no skin, eye, or mucous membrane lesions. These infants presented with lethargy and low-grade fever, followed within 24 hours by the onset of focal partial motor seizures. The seizures were refractory to anticonvulsant therapy. The mean CSF white cell count was 131 cells/mm3;the glucose and protein concentrations were in the normal range. Brain biopsy was required for the early diagnosis of HSV encephalitis. These 14 cases presented 70% (14/20) of all infants with neonatal HSV diagnosed during the study period. HSV infection should be considered in infants with no mucocutaneous lesions who have signs usually associated with bacterial sepsis or who develop focal seizures during the first three weeks of life.

[Congenital german measles encephalitis (author's transl)]

German measles is an infections exanthematous disease, long regarded as completely harmless. The clinical symptoms are banal and often go unnoticed. In complete contrast is the severe malformation of the embryo after infection early on in pregnancy, first discovered by Gregg in 1941. The virus infects the embryo via the placenta and either causes death or impairs the differentiation of embryonic tissues, causing malformation. What is understood today under the congenital German measles syndrome is considerably more extensive and includes, in addition to malformation, growth retardation, premature birth as well as possible disease of organs or organ systems continuing well after the postnatal period. We were recently able to study a case of congenital encephalitis caused by the German measles virus and here too able to demonstrate histopathologically the persistence of the infection.

Encephalitis congenita symptomatica toxica in experimental conditions

The object of the study was the cerebral cortex of newborn rat. Tissue samples for examination were collected from the 2nd to the 8th hour after birth. Experimental material was the tissue of control animals and newborns whose mothers had been treated with both ethanol and pyrazole throughout gestation, and also with either ethanol or pyrazole alone. Ethanol and pyrazole were administered by gastric tube, ethanol at doses of 8.0 g/kg body weight, pyrazole at doses of 36 mg/kg body weight. The results indicate that ethanol ingested by the mother during gestation inhibits cell maturation in the cerebral cortex, whereas the combined administration of ethanol and pyrazole produces a highly toxic action. Its morphological exponent are symptoms which support the diagnosis of encephalitis congenita symptomatica toxica.

The longitudinal course of congenital rubella encephalitis in nonretarded children

The neurologic course of congenital rubella syndrome was traced in 29 nonretarded children to 9 to 12 years. During the first two years, manifestations involved abnormal tone and reflexes (69%), motor delays (66%), feeding difficulties (48%), and abnormal clinical behavior (45%). Hearing loss was documented in 76%. From three to seven years, poor balance, motor incoordination (69%), and behavioral disturbances (66%) predominated. Hearing losses increased to 86%. Currently, at 9 to 12 years, 25 have residua which include learning deficits (52%), behavioral disturbances (48%), poor balance (61%), muscle weakness (54%), and deficits in tactile perception (41%). Two additional children now have hearing loss. The encephalitic manifestations of congenital rubella syndrome are diverse. Overriding problems differ at each phase of childhood. Current deficits influence progress in educational and home environments. For these children, adequate intelligence alone does not guarantee academic success.

Congenital herpes simplex virus, type 2, bilateral endophthalmitis

A set of dizygotic twins, both born prematurely, developed herpes simplex encephalitis shortly after birth. The second twin had unilateral keratoconjunctivitis and bilateral endophthalmitis and subsequently died from disseminated herpes infection. Herpes simplex, type 2, was isolated from conjunctiva of both eyes, cerebrospinal fluid, nasopharynx and trachea. Histologic examination of the eyes reveaed bilateral endophthalmitis with a necrotizing retinitis. Intranuclear inclusion bodies were demonstrated by light microscopy in the retina, choroid and iris, and virus particles were demonstrated by electron microscopy in the retina. The other twin recovered from a much milder disseminate herpes simplex infection without apparent ocular involvement. During pregnancy, the mother had vaginitis which was suspected, but not documented, as being herpetic in origin. The father was diagnosed as having a penile infection caused by herpes simplex.