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Biomedical subjects

M C Morriss

Publications and source records attributed to M C Morriss.

9 recordsLinked to original sources
PubMed2003

Neuroimaging of central nervous system infections.

During the past decade, advances have been made in the technology used to image the pediatric central nervous system. Although computed tomography (CT) remains the first line of imaging for the sick child admitted to the emergency room with fever and altered mental status, magnetic resonance imaging (MRI) offers superior soft tissue imaging of central nervous system (CNS) infections and advanced techniques. MRI also is the standard of care for imaging spinal infections. CT remains superior for the detection of calcification and bony detail. With the advent of new MRI sequences such as T2-weighted fluid attenuated inversion recovery (FLAIR), diffusion-weighted imaging (DWI), and magnetic resonance spectroscopy (MRS), we are able to detect early and subtle abnormalities such as the vasculitis accompanying a meningitis and to identify patterns of signal alteration that can help us be more specific about the diagnosis in lesions with similar appearances.

Central Nervous System↗
PubMed1999

Changes in brain water diffusion during childhood.

We studied the changes in brain water diffusion in childhood as seen on diffusion-weighted MRI in 30 children from 1 day of life to 17 years to provide a data base and to investigate the correlation of diffusion changes with known patterns of white matter maturation. The apparent diffusion coefficient (ADC) and apparent anisotropy (AA) were calculated in numerous regions of the brain to include major white matter tracts and gray matter. ADC and AA values were directly related to the structural maturity and compactness of the white matter tracts and changed with aging in a way that predated early myelination markers such as signal change on T1- or T2-weighted images. Diffusion of water is sensitive to structural changes in the brain such as white matter maturation and may be useful in investigating white matter disorders.

Adolescent↗
PubMed1998

Advances in pediatric neuroimaging.

Magnetic resonance evaluation of the pediatric central nervous system is rapidly improving in a number of ways: (1) anatomically with higher resolution; (2) with greater sensitivity to pathological processes characterized by increased water content utilizing fluid attenuated inversion recovery imaging (FLAIR); (3) with greater speed of acquisition with ultrafast (1 s/image) and echo planar imaging techniques (50 ms/image); (4) with measurement of cerebral blood flow as perfusion; (5) with measurement of water proton dispersion (e.g. diffusion imaging); (6) with measurement of biochemical components within tissues with proton spectroscopy; and (7) with evaluation of cortical activation with functional magnetic resonance imaging.

Central Nervous System Diseases↗
PubMed1997

Progressive multifocal leukoencephalopathy in an HIV-infected child.

A child with perinatally acquired HIV infection presented with acute neurologic deterioration. A cerebellar white matter lesion seen on CT and MRI later proved to be progressive multifocal leukoencephalopathy (PML) by histology. Although a recognized disease of HIV-infected adults, PML is certain to be seen with more frequency in HIV-infected children who are surviving longer as a result of improved medical care. Recognition of the clinical and radiographic manifestations is important because of the dismal prognosis.

AIDS Dementia Complex↗
PubMed1997

Cerebral blood flow and cranial magnetic resonance imaging in eclampsia and severe preeclampsia.

OBJECTIVE: To measure cerebral blood flow in women with eclampsia and severe preeclampsia using phase-contrast magnetic resonance imaging (MRI). METHODS: Women with eclampsia and severe preeclampsia were studied and compared with normotensive cohorts. Magnetic resonance imaging studies were performed initially in hypertensive women after seizure treatment or prophylaxis was given. Magnetic resonance imaging flow measurements were made using a phase contrast velocity imaging technique in each middle and posterior cerebral artery. Conventional brain MRI and magnetic resonance angiography of the circle of Willis were performed at the time of flow measurement. Women with preeclampsia and eclampsia served as their own controls and were matched with normotensive cohorts. All of the hypertensive women were studied again 4-5 weeks postpartum. Paired t test analysis and an analysis of variance were performed. Considering a 20% minimum detectable difference in flow, the power was 0.80, 0.92, 0.86, and 0.96 for the left and right middle cerebral arteries and the left and right posterior cerebral arteries, respectively. RESULTS: All 28 women enrolled were studied initially within 24 hours of delivery or of their most recent seizure. There were no significant differences in blood flow in either the posterior or middle cerebral arteries in women with eclampsia or severe preeclampsia between the initial studies and those 4-5 weeks postpartum, or compared with their normal counterparts. No findings of vasospasm were seen. T2-weighted brain images were markedly abnormal in all eight women with eclampsia, mildly abnormal in two of ten with severe preeclampsia, and normal in all ten controls. CONCLUSIONS: No flow changes were seen in the posterior or middle cerebral arteries of women with eclampsia and severe preeclampsia despite the presence of remarkable brain lesions in all women with eclampsia. These findings question the role of vasospasm and cerebral hypoperfusion, although a vasodilatory effect of magnesium could not be excluded.

Cerebral Angiography↗
PubMed1994

The role of early MR in the evaluation of the term infant with seizures.

PURPOSE: To define the role of MR in evaluating term neonates with seizures the most common clinical manifestation of cerebral injury in neonates. METHODS: Fifteen term infants with seizures underwent MR imaging. The presence and pattern of MR findings were compared with clinical markers of perinatal distress, cause of cerebral injury, and short-term neurologic outcome. RESULTS: Seizures were caused by hypoxic-ischemic encephalopathy in three patients, bacterial meningitis in three, and prenatal cocaine exposure in one. Nine patients had no identifiable risk factors. By MR, five patients had focal ischemic injury of the cerebral hemispheres and/or basal ganglia and brain stem. Six patients had diffuse cerebral edema: of these, five had basal ganglia edema; one had brain stem edema. One patient had superior sagittal sinus thrombosis with venous infarcts. Three patients had normal MR studies. There was no correlation between markers of perinatal distress, risk factors for seizures, and presence or pattern of MR findings. There was some correlation between MR findings of diffuse cerebral injury and neurologic outcome, and between MR findings of basal ganglia and brain stem abnormalities and neurologic outcome; these findings correlated with spasticity and hemiplegia at 6 to 24 months follow-up. CONCLUSION: The presence or pattern of MR findings does not appear to correlate with with clinical signs of perinatal distress or presumed causes of perinatal cerebral injury. Further investigation is needed to identify prospectively neonates with seizures who are at risk for significant neurologic morbidity.

Asphyxia Neonatorum↗
PubMed1993

Prevalence and clinical significance of dilated Virchow-Robin spaces in childhood.

PURPOSE: To determine the prevalence and clinical significance of dilated Virchow-Robin spaces in pediatric patients. MATERIALS AND METHODS: Cranial magnetic resonance (MR) studies of 1,250 children who underwent imaging during 12 consecutive months were prospectively evaluated. RESULTS: Thirty-seven patients had prominent Virchow-Robin spaces. The most common indications for imaging in these patients were headache (n = 10), developmental delay (n = 8), and psychiatric problems (n = 7). Medical records revealed that 12 of the 37 patients had severe headaches, 17 had moderate or severe delay in development, and 18 had serious behavioral or psychiatric problems. An association was found between presence or absence of dilated Virchow-Robin spaces and presence or absence of developmental delay (odds ratio = 4.9; 95% confidence interval [CI] = 2.1, 11.1; P < .001), psychiatric problems (odds ratio = 12.6; 95% CI = 5.0, 31.8; P < .001), and headaches (odds ratio = 37; 95% CI = 14.7, 93.2; P < .001). CONCLUSION: There appears to be a correlation between functional neuropsychiatric disorders in children and the presence of Virchow-Robin spaces in the cerebral hemispheres at MR imaging.

Adolescent↗