Biomedical subjects

S Blaser

Publications and source records attributed to S Blaser.

At least 37 records · Page 2Linked to original sources

PubMed1998

Familial growth hormone deficiency associated with MRI abnormalities.

Idiopathic growth hormone deficiency is, in most cases, a sporadic condition. In a number of these patients magnetic resonance imaging (MRI) demonstrates a small anterior pituitary, small or absent pituitary stalk, and ectopically located posterior pituitary. These findings have been attributed to a developmental defect, trauma, or ischemia at birth. We report on a case of familial isolated growth hormone deficiency with mother and son demonstrating the MRI findings described above. The son also had a Chiari type I malformation and medial deviation of the carotid arteries secondary to a narrow skull base. Testing failed to identify a mutation in either the Pit-1 gene or GH gene cluster. This case appears to be an autosomal dominant defect in early development, lending support to the hypothesis that dysgenesis, rather than birth trauma, may cause a small anterior pituitary and ectopic posterior pituitary.

Child↗

PubMed1998

Cerebellar arteriovenous malformations in children.

We review the presentation, imaging findings and outcome in 18 children with cerebellar arteriovenous malformations (AVM). This group is of particular interest because of the reported poor outcome despite modern imaging and neurosurgical techniques. All children had CT and 15 underwent catheter angiography at presentation. Several of the children in the latter part of the study had MRI. Of the 18 children, 17 presented with a ruptured AVM producing intracranial haemorrhage. The remaining child presented with temporal lobe epilepsy and was shown to have temporal, vermian and cerebellar hemisphere AVM. This child had other stigmata of Osler-Weber-Rendu syndrome. Three other children had pre-existing abnormalities of possible relevance. One had a vascular malformation of the cheek and mandible, one a documented chromosomal abnormality and another a midline cleft upper lip and palate. Six of the 17 children with a ruptured cerebellar AVM died within 7 days of the ictus. Vascular pathology other than an AVM was found in 10 of the 14 children with a ruptured cerebellar AVM who had angiography: 4 intranidal aneurysms, 5 venous aneurysms and 2 cases of venous outflow obstruction (one child having both an aneurysm and obstruction). The severity of clinical presentation was directly related to the size of the acute haematoma, which was a reasonable predictor of outcome.

Adolescent↗

PubMed1998

Cerebellar involvement in metabolic disorders: a pattern-recognition approach.

Inborn errors of metabolism can affect the cerebellum during development, maturation and later during life. We have established criteria for pattern recognition of cerebellar abnormalities in metabolic disorders. The abnormalities can be divided into four major groups: cerebellar hypoplasia (CH), hyperplasia, cerebellar atrophy (CA), cerebellar white matter abnormalities (WMA) or swelling, and involvement of the dentate nuclei (DN) or cerebellar cortex. CH can be an isolated typical finding, as in adenylsuccinase deficiency, but is also occasionally seen in many other disorders. Differentiation from CH and CA is often difficult, as in carbohydrate deficient glycoprotein syndrome or 2-L-hydroxyglutaric acidaemia. In cases of atrophy the relationship of cerebellar to cerebral atrophy is important. WMA may be diffuse or patchy, frequently predominantly around the DN. Severe swelling of white matter is present during metabolic crisis in maple syrup urine disease. The DN can be affected by metabolite deposition, necrosis, calcification or demyelination. Involvement of cerebellar cortex is seen in infantile neuroaxonal dystrophy. Changes in DN and cerebellar cortex are rather typical and therefore most helpful; additional features should be sought as they are useful in narrowing down the differential diagnosis.

Adolescent↗

PubMed1998

Etiology of acute childhood encephalitis at The Hospital for Sick Children, Toronto, 1994-1995.

Of 145 patients admitted to our hospital because of encephalitis-like illness, 50 patients hospitalized for > or =72 hours underwent standardized microbiological investigations. A confirmed or probable etiologic agent was identified in 20 cases (40%), including Mycoplasma pneumoniae (9 cases). M. pneumoniae and enterovirus (2), herpes simplex virus (4), Epstein-Barr virus (1), human herpes-virus 6 (HHV-6) (1), HHV-6 and influenza virus type A (1), influenza virus type A (1), and Powassan virus (1). In 13 cases (26%), a possible pathogen was identified, including M. pneumoniae in nine cases. Presenting features included fever (80% of patients), seizures (78%), focal neurological findings (78%), and decreased consciousness (47%). The frequency of findings at the time of admission vs. later in hospitalization was as follows: pleocytosis, 59% vs. 63%; electroencephalogram abnormalities, 87% vs. 96%; and neuroimaging abnormalities, 37% vs. 69%, respectively. The outcomes at the time of discharge were as follows: normal results of physical examination, 32% (16) of the patients; death, 2% (1); motor difficulties, 26% (13); global neurological deficits, 16% (severe, 6; mild, 2); mental status changes, 14% (7); visual defects, 8% (4); and hearing impairment, 2% (1).

Acute Disease↗

PubMed1998

Fetal bilateral subdural haemorrhages. Prenatal diagnosis and spontaneous resolution by time of delivery.

We report a patient diagnosed prenatally on routine fetal ultrasound, at 30 weeks' gestation, with subdural haemorrhage. The mother had suffered a mild abdominal trauma and had Factor XI deficiency; however, both were felt to be aetiologically insignificant. Prenatal follow-up showed a complete resolution of the haematoma and no postnatal sequelae have been noted to date. The aetiologies and outcomes in the few previously reported cases are reviewed and compared with our case.

Adult↗

PubMed1998

MR imaging in idiopathic growth hormone deficiency.

BACKGROUND AND PURPOSE: MR imaging findings of one or more of the following has been suggested to be a sensitive and specific indicator of hypopituitarism: small anterior pituitary gland, attenuated or absent pituitary stalk, and ectopic posterior pituitary. We hypothesized that these MR findings would be common in our group of patients with idiopathic isolated growth hormone deficiency (GHD) or multiple pituitary hormone deficiencies (MPHD) and would be a good indicator of the severity of the hypopituitarism. METHODS: MR images were obtained for 35 patients with idiopathic GHD (20 with isolated GHD and 15 with MPHD; age range, 2 to 17 years) and analyzed to define one or more of the following triad of abnormalities: 1) small/absent anterior pituitary, 2) truncated/absent pituitary stalk, and 3) ectopic posterior pituitary, as well as for any other associated anomalies. The findings were correlated with the clinical and biochemical presentation. RESULTS: Pituitary abnormalities were common in both groups (80% with isolated GHD, 93% with MPHD). We found a high frequency of midline CNS malformations, including optic nerve hypoplasia (9%), Chiari type I malformations (20%), and medial deviation of the carotid arteries (37%). Breech delivery, neonatal hypoglycemia, jaundice, micropenis, or single central incisor occurred equally with both isolated GHD and MPHD. In patients whose peak growth hormone level was less than 3 microg/L (n = 19), 90% had the MR triad, compared with 390% of those with growth hormone levels 3 microg/L or greater or less than 8 microg/L (n = 13) (P <.01). Almost all (92%) of those with ectopic posterior pituitary had anterior pituitary heights less than -2 SD for age. CONCLUSION: MR abnormalities were common in children with both isolated GHD and MPHD and were closely associated with peak growth hormone levels less than 3 microg/L. The presence of other CNS and clinical findings (eg, single central incisor and micropenis) supports the theory of an embryologic defect as the cause of the pituitary abnormalities.

Adolescent↗

PubMed1997

Omphalocele in Miller-Dieker syndrome: expanding the phenotype.

We report on a patient prenatally diagnosed with omphalocele, mild cerebral ventriculomegaly, nuchal fold thickening, and cystic changes in the umbilical cord who was found postnatally to have lissencephaly type I. Prenatal chromosome analysis showed a normal male karyotype; however, postnatal high resolution banding and FISH analysis, using a probe for locus D17S379 in chromosome region 17p13.3, demonstrated a deletion at 17p13.3 consistent with Miller-Dieker syndrome (MDS). A review documented four more cases with MDS/isolated lissencephaly/17p-, with omphalocele. Because MDS is a contiguous gene disorder, we speculate that a gene or genes in this region have a major role in the closure of the lateral folds or the return of the midgut from the body stalk to the abdomen at 5-11 weeks of gestation. Prenatal diagnosis of omphalocele with mild ventriculomegaly should prompt FISH analysis for a deletion in 17p13.3.

Abnormalities, Multiple↗

PubMed1997

99mTechnetium HMPAO imaging in children with the Sturge-Weber syndrome: a study of nine cases with CT and MRI correlation.

Demonstration of the full extent of abnormality in patients with the Struge-Weber syndrome (SWS) is important for prognosis and in planning surgery to remove the seizure focus. We compared single-photon emission computed tomography (SPECT), MRI and CT in nine children under the age of 4 years with seizures as part of SWS, in an attempt to determine the optimal method of imaging in different clinical settings. Seven unilateral and two bilateral cases were studied by interictal 99mtechnetium hexamethylpropyleneamineoxime (HMPAO) SPECT, and contrast-enhanced CT and MRI, giving information on 11 abnormal hemispheres. All imaging modalities showed abnormalities in every child. Perfusion imaging showed focal regions of decreased uptake in 9 of 11 (82%) abnormal hemispheres and demonstrated a widespread decrease but no focal defect in 2; it also revealed crossed cerebellar diaschisis in 2 cases. CT demonstrated typical gyriform calcification in 9 of 11 (82%) affected hemispheres. Contrast-enhanced MRI showed more extensive involvement than contrast-enhanced CT in 5 of 11 (45%) cases. The area of hypoperfusion shown by SPECT was smaller than the area of contrast enhancement on MRI in 6 of 11 cases (55%), comparable in 3 (27%) and larger in 2 cases (18%). CT is sufficient to confirm the clinical diagnosis of SWS, but MRI frequently shows more extensive abnormal areas. 99mTc HMPAO imaging is a useful addition when it is important to know the full extent of the disease, for example prior to surgery. It is likely to detect areas of hypoperfusion, representing ischaemic regions, which may act as an epileptogenic focus and may not be shown by CT or MRI.

Adolescent↗

PubMed1997

Coexistence of hemimegalencephaly and chronic encephalitis. Detection of cytomegalovirus by the polymerase chain reaction.

We report the extraordinary association of hemimegalencephaly with chronic encephalitis and cytomegalovirus (CMV) positivity in a 5-month-old infant with intractable seizures and a left hemisphere resection. Microscopy revealed a severe neuronal migration disorder (NMD) with fusion of gyri, marked disarray of neuronal lamination, neuronal gigantism and extensive neuronal heterotopias. Also widespread were microglial nodules, gliosis and nodular calcifications and some foci of frank necrosis with calcification. Occasional perivascular and leptomentingeal lymphocytic infiltrates were present. No viral inclusions were identifiable. Polymerase chain reaction on multiple specimens showed unequivocal CMV positivity. In intrauterine CMV infection. NMDs such as polymicrogyria are well recognized, but the association of hemimegalencephaly with CMV infection has not previously been described. Our finding of chronic encephalitis with CMV positivity and hemimegalencephaly in the same patient raises questions about the role of CMV in the etiopathogenesis of the NMD.

Brain↗

PubMed1997

Intracranial and spinal metastases from a ganglioglioma with unusual cytogenetic abnormalities in a patient with complex partial seizures.

We describe an unusual clinical presentation of a ganglioglioma in a patient with complex partial seizures. The patient underwent a right temporal lobectomy with subtotal tumor resection at age 15 years, followed by a complete resection 1 year later. Follow-up MRI scan a year later documented recurrence and leptomeningeal dissemination. Another biopsy was performed. Pathological examination revealed similar histology in all three resections, with a ganglioglioma showing no evidence of anaplasia. The tumor exhibited a number of karyotypic abnormalities, notably, a paracentric inversion of chromosome 7. In summary, despite lacking anaplastic features by conventional histological criteria, this ganglioglioma showed an unsusual karyotype and demonstrated radiological evidence of widespread dissemination.

Adolescent↗

PubMed1997

Positive epileptiform discharges in children with neuronal migration disorders.

Most epileptiform abnormalities show a negative polarity on EEG. Focal positive spike waves have rarely been identified in seizure disorders and are generally associated with physiological and neurological impairment. Results of EEG, computed tomography, MRI, and pathologic studies of 15 children with focal neuronal migration disorders who underwent surgery for refractory localization-related epilepsy were compared to examine the association between positive discharges and other findings. Subjects were studied both ictally and interictally by scalp EEG with the International 10-20 system and zygomatic or sphenoidal electrodes, and video EEG telemetry. The 5 children with positive discharges were significantly more likely to develop hemiparesis during the preoperative period (P < or = .025). Correlations were observed between positive discharges and lesions apparent on MRI situated around the rolandic fissure (P < or = .025). Children with positive discharges had a significantly less favorable outcome after surgical treatment (P < or = .025). Positive epilepti-form discharges in children with neuronal migration disorders may signal a more dysfunctional cortex leading to a focal neurological deficit or a more extended lesion than is detected on MRI. This would explain the less favorable outcome of seizures after surgery, since the epileptogenic areas and neuronal migration lesions cannot be completely resected.

Brain↗

PubMed1997

Evaluation of the role of routine serial cranial computed tomography in the management of children with human immunodeficiency virus infection.

OBJECTIVE: To review the impact of routine follow-up cranial computed tomography (CT) scans on the management of children with human immunodeficiency virus (HIV) infection. DESIGN: Longitudinal data collected from 58 HIV-infected children followed in one center for mean of 3.8 +/- 1.8 years. SETTING: HIV/AIDS pediatric program following over 90% of the identified HIV-infected children in one region in Canada. RESULTS: The baseline CT scans showed intracranial abnormalities in 35 of 58 children (60%). In five children with basal ganglia calcifications (BGC) without cerebral atrophy, there has not been progressive encephalopathy. For the 43 children who had serial CT scans for routine follow-up, 34 (79%) had changes in the scans that were concordant with the clinical assessment. In all but five children with progressive ventricular and sulcal dilatation on CT scan, there was simultaneous clinical evidence of encephalopathy. Those five children were already on antiretroviral therapy, and therapy was not changed in response to the CT scan findings. CONCLUSION: Baseline CT scans provide useful diagnostic and prognostic information. Further research is needed to evaluate the role of cranial CT imaging in the management of pediatric HIV encephalopathy.

AIDS Dementia Complex↗

PubMed1996

Abnormal ocular enhancement in Sturge-Weber syndrome: correlation of ocular MR and CT findings with clinical and intracranial imaging findings.

PURPOSE: To estimate the prevalence of abnormal ocular enhancement in children with Sturge-Weber syndrome as detected with MR imaging and CT and to correlate this with the clinical, fundoscopic, and intracranial imaging findings. METHODS: Fifteen children, 4 years old or younger, with Sturge-Weber syndrome were examined with enhanced CT and MR imaging. Eleven children had unilateral intracranial involvement and 4 had bilateral involvement, for a total of 19 abnormal hemispheres and related orbits. The presence of ocular enhancement was compared with the fundoscopic findings independently. Ocular enhancement was correlated with the extent of leptomeningeal disease, the severity of the cutaneous lesion, and the presence of glaucoma by the calculation of likelihood ratios and 95% confidence limits. RESULTS: Seven of the 15 patients had abnormal ocular enhancement, which was present in 10 (53%) of the eyes associated with the 19 abnormal hemispheres. MR imaging showed choroidal hemangioma in 7 of 8 patients in whom hemangiomas were shown at fundoscopy. The likelihood of ocular enhancement was increased with the presence of bilateral disease, extensive facial nevi, and glaucoma; there was no significant correlation with the extent of hemispheric involvement. CONCLUSION: Both enhanced MR imaging and CT can show diffuse choroidal hemangioma in patients with Sturge-Weber syndrome. However, MR imaging is more sensitive and is recommended to aid in the detection of abnormalities with preventable late complications.

Brain↗

PubMed1996

Choroid plexus size in young children with Sturge-Weber syndrome.

PURPOSE: To assess the size of the choroid plexus in young children with unilateral and bilateral Sturge-Weber syndrome. METHODS: Subjects included 15 children 4 years old or younger with Sturge-Weber syndrome. Eleven cases were unilateral and four were bilateral. Unilateral or bilateral involvement was determined by the distribution of abnormal leptomeningeal enhancement on MR images. The diameters of the choroid plexus were measured on contrast-enhanced axial MR images. The choroid plexus of the affected and unaffected sides in these cases were compared with those of 15 age-matched children without Sturge-Weber syndrome who were being examined for seizures. RESULTS: Our results show a wide variation in the size of the choroid plexus in children with Sturge-Weber syndrome; however, plexus associated with a hemisphere affected by Sturge-Weber syndrome were significantly larger than those on the unaffected side and in the age-matched control group. The size of the choroid plexus was positively correlated with the extent of leptomeningeal involvement as demonstrated by abnormal contrast enhancement. CONCLUSION: The choroid plexus is enlarged early in the course of Sturge-Weber syndrome in both unilateral and bilateral cases. There is a positive correlation between choroid plexus size and extent of leptomeningeal involvement in children with Sturge-Weber syndrome.

Child, Preschool↗

PubMed1995

Prenatal diagnosis of retinal nonattachment in the Walker-Warburg syndrome.

We report on the prenatal ultrasonographic diagnosis of Walker-Warburg syndrome based on cerebral and ocular findings. The ultrasound study done at 37 weeks gestation documented hydrocephalus and retinal nonattachment consistent with this syndrome. The ability to detect retinal nonattachment prenatally may have implications for the prenatal diagnosis of other conditions which have early retinal nonattachment as one of their findings. However, it is uncertain how early in pregnancy this defect can be detected.

Abnormalities, Multiple↗

PubMed1995

Central precocious puberty: evaluation by neuroimaging.

To evaluate the incidence of abnormal intracranial findings in children with central precocious puberty, 62 children (51 girls, 11 boys) were examined by computerized tomography and/or magnetic resonance imaging (MRI) of the brain. Forty-four had normal examinations; 18 (11 girls, 7 boys) showed intracranial pathologies, including hamartoma of the tuber cinereum (8 cases), parenchymal loss (3 cases), hypothalamic-chiasmatic lesions (2 cases), lesions of the corpus callosum (2 cases), suprasellar cyst (1 case), and pineal cyst and mesiotemporal sclerosis (1 case each). Based on the correlation between the clinical and the imaging results of this series, the authors recommend MRI as the imaging method of choice in the investigation of precocious puberty.

Brain Diseases↗

PubMed1995

Cerebral vein thrombosis in childhood systemic lupus erythematosus.

We describe three cases of cerebral vein thrombosis (CVT) in girls with systemic lupus erythematosus. Severe, persistent, unremitting headache was a common manifestation. In the first patient, although the clinical features were suggestive of CVT, the diagnosis was delayed and she had a significant cerebral infarct. In the other two patients the diagnosis was made earlier and led to more rapid treatment; the institution of early therapy may have prevented further sequelae. The CVT was diagnosed in all patients with a combination of computed tomography and magnetic resonance imaging studies without the need for angiography. All patients were treated for their underlying systemic lupus erythematosus and with anticoagulation. All are receiving long-term low doses of warfarin and have not had any recurrences.

Adolescent↗

PubMed1995

Ornithine transcarbamylase deficiency in females: an often overlooked cause of treatable encephalopathy.

Ornithine transcarbamylase deficiency is an X-linked recessive disorder of urea biosynthesis characterized by recurrent, often fatal, hyperammonemic encephalopathy in affected males; carrier females are usually asymptomatic. We report here the clinical and laboratory findings in five symptomatic heterozygous females with ornithine transcarbamylase deficiency. In each case, the onset of symptoms occurred in the 1st year of life, but diagnosis was delayed by up to 15 years. Symptoms included recurrent vomiting with lethargy (five patients), dietary protein intolerance (five), irritability (four), severe acute encephalopathy (three), ataxia (three), and acute hemiparesis (two). All eventually showed evidence of developmental delay or learning difficulties. Two of the three who experienced severe, acute, hyperammonemic encephalopathy suffered serious, permanent neurologic sequelae. Three of the patients showed decreased ornithine transcarbamylase activity in liver obtained by needle biopsy, and the other two had marked orotic aciduria associated with hyperammonemia. Neuroimaging studies demonstrated persistent abnormal lobar attenuation and abnormal signal on computed tomographic scan and magnetic resonance imaging. All patients showed marked symptomatic improvement on treatment with dietary protein restriction supplemented by pharmacologic measures to increase nonprotein nitrogen excretion. Ornithine transcarbamylase deficiency should be considered in the differential diagnosis of acute or chronic encephalopathy in females at any age.

Adolescent↗