Biomedical subjects

Susan Blaser

Publications and source records attributed to Susan Blaser.

At least 19 recordsLinked to original sources

PubMed2006

The natural history of juvenile or subacute GM2 gangliosidosis: 21 new cases and literature review of 134 previously reported.

OBJECTIVE: Juvenile GM2 gangliosidosis is a group of inherited neurodegenerative diseases caused by deficiency of lysosomal beta-hexosaminidase resulting in GM2 ganglioside accumulation in brain. The purpose of this study was to delineate the natural history of the condition and identify genotype-phenotype correlations that might be helpful in predicting the course of the disease in individual patients. METHODS: A cohort of 21 patients with juvenile GM2 gangliosidosis, 15 with the Tay-Sachs variant and 6 with the Sandhoff variant, was studied prospectively in 2 centers. Our experience was compared with previously published reports on 134 patients. Information about clinical features, beta-hexosaminidase enzyme activity, and mutation analysis was collected. RESULTS: In our cohort of patients, the mean (+/-SD) age of onset of symptoms was 5.3 +/- 4.1 years, with a mean follow-up time of 8.4 years. The most common symptoms at onset were gait disturbances (66.7%), incoordination (52.4%), speech problems (28.6%), and developmental delay (28.6%). The age of onset of gait disturbances was 7.1 +/- 5.6 years. The mean time for progression to becoming wheelchair-bound was 6.2 +/- 5.5 years. The mean age of onset of speech problems was 7.0 +/- 5.6 years, with a mean time of progression to anarthria of 5.6 +/- 5.3 years. Muscle wasting (10.6 +/- 7.4 years), proximal weakness (11.1 +/- 7.7 years), and incontinence of sphincters (14.6 +/- 9.7 years) appeared later in the course of the disease. Psychiatric disturbances and neuropathy were more prevalent in patients with the Sandhoff variant than in those with the Tay-Sachs variant. However, dysphagia, sphincter incontinence, and sleep problems occurred earlier in those with the Tay-Sachs variant. Cerebellar atrophy was the most common finding on brain MRI (52.9%). The median survival time among the studied and reviewed patients was 14.5 years. The genotype-phenotype correlation revealed that in patients with the Tay-Sachs variant, the presence of R178H and R499H mutations was predictive of an early onset and rapidly progressive course. The presence of either G269S or W474C mutations was associated with a later onset of symptoms along with a more slowly progressive disease course. CONCLUSIONS: Juvenile GM2 gangliosidosis is clinically heterogeneous, not only in terms of age of onset and clinical features but also with regard to the course of the disease. In general, the earlier the onset of symptoms, the more rapidly the disease progresses. The Tay-Sachs and Sandhoff variants differed somewhat in the frequency of specific clinical characteristics. Speech deterioration progressed more rapidly than gait abnormalities in both the Tay-Sachs variant and Sandhoff variant groups. Among patients with the Tay-Sachs variant, the HEXA genotype showed a significant correlation with the clinical course.

Acute Disease↗

PubMed2006

Imaging of the brain in full-term neonates: does sonography still play a role?

To date the literature comparing the usefulness of US and MR examinations of the neonatal brain suggests that US is not as effective a modality as MR. However, available studies were done on older equipment and published descriptions of the abnormalities found in the term brain are often incomplete. The purpose of this article is to emphasize technical factors that may be useful to optimize US imaging of the term neonatal brain, to provide a description of the sonographic findings in the brain in full-term neonates with hypoxic-ischaemic injury and to provide some data regarding the accuracy of sonography. While MR imaging may reveal abnormalities of the brain more floridly than sonography, we believe that sonography remains an extremely useful modality for evaluation of the full-term neonatal brain and it is probably a more accurate modality in this age group than the current literature suggests. Further prospective studies comparing sonographic and MR imaging findings are required to document the accuracy of sonography better and to help us define the role of this modality better. Such studies may help us select which patients really require MR imaging.

Asphyxia Neonatorum↗

PubMed2006

Prenatal detection of microtia by MRI in a fetus with trisomy 22.

Trisomy 22 is a rare chromosomal abnormality infrequently detected prenatally. External ear abnormalities, in particular microtia, are often associated with trisomy 22, but prenatal detection of microtia has not been reported in association with trisomy 22. We report a fetus with trisomy 22, with fetal MRI findings of microtia, craniofacial dysmorphism, and polygyria. Fetal MRI is a useful tool for auricular assessment and might have utility in the prenatal detection of chromosomal abnormalities, especially among fetuses with structural anomalies.

Autopsy↗

PubMed2006

Diffusion tensor imaging of midline posterior fossa malformations.

BACKGROUND: Diffusion tensor imaging and tractography have been used to evaluate a variety of brain malformations. However, these studies have focused mainly on malformations involving the supratentorial compartments. There is a paucity of data on diffusion tensor imaging of posterior fossa malformations. OBJECTIVE: To describe the color vector maps and modified or abnormal tracts of midline posterior fossa malformations. MATERIALS AND METHODS: Diffusion tensor imaging was performed in one patient with rhombencephalosynapsis and two with Joubert syndrome. Color vector maps of fractional anisotropy were used to place a region of interest for seed point of fiber tracking. RESULTS: The vermis was severely hypoplastic or absent in rhombencephalosynapsis and Joubert syndrome. In rhombencephalosynapsis, vertically oriented fibers were visualized in the midportion of the cerebellum. The location of the deep cerebellar nuclei could be inferred from the amiculum and were medially located in rhombencephalosynapsis. In the two patients with Joubert syndrome, the horizontally arranged superior cerebellar peduncles were well demonstrated on the color vector maps. Failure of the superior cerebellar peduncles to decussate in the mesencephalon was also well demonstrated on both color vector maps and tractography. The deep cerebellar nuclei were more laterally located in Joubert syndrome. CONCLUSION: The use of tractography in midline posterior fossa malformations expands our understanding of these malformations.

Abnormalities, Multiple↗

PubMed2006

Basal ganglia germinoma in children with associated ipsilateral cerebral and brain stem hemiatrophy.

BACKGROUND: Germinoma is the most common and least-malignant intracranial germ cell tumor, usually found in the midline. Germinoma that arises in the basal ganglia, called ectopic germinoma, is a rare and well-documented entity representing 5% to 10% of all intracranial germinomas. The association of cerebral and/or brain stem atrophy with basal ganglia germinoma on CT and MRI is found in 33% of the cases. OBJECTIVE: To review the literature and describe the CT and MRI findings of basal ganglia germinoma in children, known as ectopic germinoma, with associated ipsilateral cerebral and brain stem hemiatrophy. MATERIALS AND METHODS: Three brain CT and six brain MRI studies performed in four children at two institutions were retrospectively reviewed. All patients were male (case 1, 14 years; case 2, 13 years; case 3, 9 years; case 4, 13 years), with pathologically proved germinoma arising in the basal ganglia, and associated ipsilateral cerebral and/or brain stem hemiatrophy on the first imaging study. It is important to note that three of these children presented with cognitive decline, psychosis and slowly progressive hemiparesis as their indication for imaging. RESULTS: Imaging results on initial scans were varied. In all patients, the initial study showed ipsilateral cerebral and/or brain stem hemiatrophy, representing Wallerian degeneration. All patients who underwent CT imaging presented with a hyperdense or calcified lesion in the basal ganglia on unenhanced scans. Only one of these lesions had a mass effect on the surrounding structures. In one of these patients a large, complex, heterogeneous mass appeared 15 months later. Initial MR showed focal or diffusely increased T2 signal in two cases and heterogeneous signal in the other two. CONCLUSION: The association of a focal lesion in the basal ganglia of children with progressive hemiparesis, neuropsychiatric symptoms and ipsilateral cerebral and/or brain stem hemiatrophy should prompt the diagnosis of ectopic germinoma, avoiding delay in the diagnosis and further irreversible clinical deterioration, in a malignancy with an otherwise favorable prognosis. In these patients, hemiatrophy preceding or accompanying the imaging depiction of a basal ganglia mass lesion is thought to be caused by a paraneoplastic process.

Adolescent↗

PubMed2006

A case series of pediatric primary central nervous system lymphoma: favorable outcome without cranial irradiation.

PURPOSE: To describe the outcome of childhood primary central nervous system lymphoma (PCNSL) treated with chemotherapy alone or with chemotherapy plus cranial radiotherapy (CRT). METHODS: Retrospective chart review of children with PCNSL at six tertiary care pediatric centers. RESULTS: Eight immunocompetent and four immunocompromised children were included. Ten children received chemotherapy alone without CRT, with most receiving high-dose methotrexate and high-dose cytarabine. Five year event-free survival (EFS) in this group was 70.0 +/- 14.5%. Two children received chemotherapy plus CRT; one relapsed and died while the other is alive in remission. Three children died, including two from relapsed disease. The other child with human immunodeficiency virus infection died of an opportunistic infection while in remission following chemotherapy alone. CONCLUSIONS: Most children with PCNSL can achieve long-term remissions with chemotherapy alone without CRT. Multi-center prospective studies are needed to confirm or refute these results in a larger number of patients.

Adolescent↗

PubMed2006

Duodenal and biliary atresia associated with facial, thyroid and auditory apparatus abnormalities: a new mandibulofacial dysostosis syndrome?

We report a female child born at 36 weeks of gestation with multiple abnormalities including dysmorphic and coarse facial features with features of mandibulofacial dysostosis that include bilateral microtia with the absence of external auditory meati and Mondini dysplasia as well as, duodenal atresia, intestinal malrotation, anterior displacement of the anus, left hemiaplasia of the thyroid and biliary atresia in sibs. The associations of duodenal atresia with intrahepatic and extrahepatic biliary atresia in sibs have been reported, suggesting an autosomal recessive syndrome. However, the associated external, middle and internal ear anomalies and the thyroid malformation, however, have not been reported in this condition. To the best of our knowledge, this is a hitherto new syndrome with an unknown inheritance.

Abnormalities, Multiple↗

PubMed2006

Temporal bone imaging in GJB2 deafness.

OBJECTIVE: To describe temporal bone findings on computed tomography (CT) imaging in GJB2-related hearing loss (HL). We asked whether evaluation of the temporal bone is required in individuals with biallelic GJB2 mutations. STUDY DESIGN: Randomized, blinded, controlled, prospective measurement. METHODS: Blood from 264 pediatric cochlear implant users was analyzed for mutations in the GJB2 gene. Thirty-six aspects of the temporal bone on CT imaging were evaluated in 53 individuals (106 ears) with biallelic disease causing GJB2 mutations. A subset of patients was age matched and compared with normally hearing individuals. Subjects with biallelic GJB2 mutations were tested for mutations in the SLC26A4 gene to rule out Pendred syndrome as a confounding cause of large vestibular aqueduct syndrome. RESULTS: Approximately 53% of ears of subjects (72% of subjects) with biallelic GJB2 mutations had at least one temporal bone anomaly. The most common findings were 1) dilated endolymphatic fossa (28%); 2) hypoplastic modiolus (25%); 3) large vestibular aqueduct (8%); 4) hypoplastic horizontal semicircular canal (8%); 5) hypoplastic cochlea (4%). Compared with normally hearing individuals, the GJB2 group had hypoplasia of the cochlear nerve canal, lateral semicircular canal vestibule, internal auditory canal (t tests, P < .001), and were 11 times more likely to have a hypoplastic modiolus. Dilated endolymphatic fossae were 1.4 times more common in the GJB2 group, and large vestibular aqueducts were 3 times more common in the GJB2 group, as compared with normally hearing controls. CONCLUSIONS: Temporal bone anomalies are common in GJB2-related HL, and imaging of the temporal bone should be included in routine evaluation of these individuals.

Child↗

PubMed2006

Inner ear dysplasia is common in children with Down syndrome (trisomy 21).

OBJECTIVES/HYPOTHESIS: Middle and external ear anomalies are well recognized in Down syndrome (DS, trisomy 21). Inner ear anomalies are much less frequently described. This study reviews inner ear morphology on imaging to determine the prevalence of cochlear and vestibular anomalies in children with DS. STUDY DESIGN: The authors conducted a retrospective review of imaging features of (DS) inner ear structures. METHODS: Fifty-nine sequential patients with DS with imaging of the inner ear were identified by a radiology report text search program. Quantitative biometric assessment of the inner ear was performed on patients with high-resolution computed tomography or magnetic resonance images of the petrous bone. Petrous imaging was performed for evaluation of inflammatory disease or hearing loss. Spinal imaging, which included petrous views, was performed in most cases to exclude C1 to 2 dislocation, a potential complication of DS. Measurements were compared with normative data. RESULTS: Inner ear dysplasia is much more common in DS than previously reported. Inner ear structures are universally hypoplastic. Vestibular malformations are particularly common and a small bony island of the lateral semicircular canal (<3 mm in diameter) appears highly typical. Additional findings in some patients were persistent lateral semicircular anlage with fusion of the lateral semicircular canal and vestibule into a single cavity, vestibular aqueduct and endolymphatic sac fossa enlargement, cochlear nerve canal hypoplasia, and stenosis or duplication of the internal auditory canal. Stenosis of the external meatus, poor mastoid pneumatization, middle ear and mastoid opacification, and cholesteatoma were common, as expected.

Adolescent↗

PubMed2006

Molar tooth sign in fetal brain magnetic resonance imaging leading to the prenatal diagnosis of Joubert syndrome and related disorders.

Joubert syndrome is a rare autosomal recessive disorder characterized by ataxia, developmental delay, and oculomotor and respiratory abnormalities in relation to cerebellar vermian and midbrain dysgenesis. The midbrain dysgenesis is responsible for the molar tooth sign on axial magnetic resonance imaging (MRI). This classic hallmark of Joubert syndrome has been identified in other disorders sharing overlapping clinical and radiologic features with Joubert syndrome. Recent identification of two different genes points to genetic heterogeneity in this group of disorders, now entitled Joubert syndrome and related disorders, making a genetic prenatal diagnosis not readily available. In addition, fetal ultrasonography lacks sensitivity in regard to posterior fossa malformation. Fetal MRI is now acknowledged as the method of choice to delineate posterior fossa malformation in a fetus. The identification of a molar tooth sign has, however, rarely been documented by a fetal brain MRI. We report a case of Joubert syndrome diagnosed prenatally using fetal MRI. We also discuss the etiology of Joubert syndrome in view of the recent genetic advances and murine models of cerebellar dysgenesis.

Abnormalities, Multiple↗

PubMed2006

Weight gain in craniopharyngioma--a model for hypothalamic obesity.

OBJECTIVES: To evaluate (1) the pattern of post-operative weight gain and (2) the risk factors associated with the development of post-operative weight gain and obesity in children treated for craniopharyngioma. STUDY DESIGN: The records of 43 children who had primary craniopharyngioma resection were reviewed. Neurological, endocrine, anthropometric and radiological risk factors for the development of obesity and for post-operative increase in BMI SDS were analyzed. RESULTS: Twenty-five patients (58%) became obese post-operatively. Obesity was significantly associated with higher BMI SDS at presentation and pre-operative hydrocephalus (p < 0.05). Increased BMI SDS from 0-12 months was significantly associated with post-operative MRI evidenced hypothalamic damage and higher BMI at presentation (p < 0.05). CONCLUSIONS: Children who developed hypothalamic obesity had a significant, rapid BMI increase over the first 6 months, followed by stabilization, with no regression of BMI SDS.

Adolescent↗

PubMed2005

Petrified ears in a patient with Keutel syndrome: temporal bone CT findings.

We present unusual imaging findings of petrified ears in a 9-year-old girl with Keutel syndrome. The patient presented for a temporal bone study for hearing loss. CT scan showed middle and inner ear abnormalities along with extensive and unsuspected calcification of the external ears and ossicular ligaments. On further investigation, the patient was found to have diffuse cartilage calcification in the larynx and tracheobronchial tree, brachytelephalangism and peripheral pulmonary stenosis suggestive of Keutel syndrome. Confirmation was obtained by mutation analysis.

Abnormalities, Multiple↗

PubMed2005

Cavum veli interpositi: prenatal diagnosis and postnatal outcome.

We describe the finding of cavum veli interpositi (CVI) on fetal ultrasound and MRI and the postnatal MRI and developmental follow-up in two cases. The first case was diagnosed on fetal ultrasound at 33 weeks' gestation and confirmed on fetal MRI. No abnormalities were detected on postnatal examinations and the brain MRI at 1 year of age showed no changes. At 4 years of age, his growth and development were normal.The second case was diagnosed with CVI on fetal ultrasound and MRI at 33.5 weeks' gestation. Postnatal examination showed no abnormalities, and brain MRI at 8 months of age revealed that the CVI was unchanged, but there was a dilated cavum septum pellucidum and cavum vergae. Her growth and development during the first 4 years of life were normal. CVI is a rare fetal ultrasound finding, which seems to be benign. However, further neurodevelopmental follow-up is needed to confirm this observation.

Adult↗

PubMed2005

Retropharyngeal and parapharyngeal infections in children: the Toronto experience.

OBJECTIVE: To review the Hospital of Sick Children, Toronto's experience of the diagnosis and management of retropharyngeal and parapharyngeal infections with particular emphasis on the role of computed tomography (CT) imaging in diagnosing the presence of an abscess. METHODS: A retrospective analysis of all patients diagnosed with retropharyngeal and parapharyngeal infections from 1987 to 1999 was performed. Demographic data, presenting symptoms, season of presentation, management and complications were reviewed. The CT scans of 27 patients who underwent surgical treatment were retrospectively examined by two neuroradiologists who were blinded to the patient's history and outcome. The sensitivity, specificity and predictive values for the specific features and overall assessment were calculated. RESULTS: Fifty-four children were identified. There were 46 retropharyngeal infections, 6 parapharyngeal infections and 2 patients had both retropharyngeal and parapharyngeal infections. All patients were treated with parenteral antibiotics. Thirty-seven patients underwent surgical drainage and in 27 there was a positive finding of pus. The retrospectively assessed CT scans of the 21 patients who underwent surgery were found to have a sensitivity of 81% in detecting an abscess by CT scan but the specificity was 57%. There were four complications including mediastinitis, aspiration pneumonia, internal jugular vein thrombosis and common carotid artery aneurysm. All patients recovered but abscess recurred in five patients. CONCLUSION: Not all patients with retropharyngeal and parapharyngeal abscesses require surgery. Whilst CT scans are helpful in diagnosing and assessing the extent of these infections they are not always accurate in detecting an abscess. A decision to drain an abscess should therefore not be made based solely on the CT findings.

Abscess↗

PubMed2005

Neurological complications of kernicterus.

OBJECTIVE AND BACKGROUND: Prevention of bilirubin encephalopathy relies on the detection of newborns who are at risk of developing serious hyperbilirubinemia. The objective of this study was to reassess the clinical syndrome of kernicterus as neurodiagnostic studies have become more readily available and can be used to evaluate these infants. METHODS: The study population was neonates born at term or near term admitted to The Hospital for Sick Children in Toronto, Ontario, Canada, between January 1990 and May 2000. During the study period, there were 9776 admissions (average number of admissions per year--888 infants). The inclusion criteria were that patients had total serum bilirubin levels of >400 micromol/L at the time of diagnosis and no evidence of hypoxic ischemic encephalopathy. Records were reviewed to establish neurodevelopment outcomes. RESULTS: Twelve neonates (nine males) were identified. Bilirubin levels at the time of diagnosis ranged from 405 to 825 micromol/L. Causes of these elevated levels included glucose-6-phosphate dehydrogenase deficiency (seven patients), dehydration (three patients), sepsis (one patient), and was undetermined in one patient. Abnormal visual evoked potentials were found in three of nine patients and abnormal brainstem auditory evoked potentials in seven of ten patients. Abnormal electroencephalograms were documented in five patients studied. Brain magnetic resonance imaging results were abnormal in three of four patients. CONCLUSIONS: Magnetic resonance imaging typically showed an increased signal in the posteromedial aspect of the globus pallidus and was, therefore, useful in the assessment of the structural changes of chronic bilirubin encephalopathy after kernicterus.

Behavior↗

PubMed2005

Temporal bone findings on computed tomography imaging in branchio-oto-renal syndrome.

OBJECTIVES/HYPOTHESIS: To describe temporal bone findings using visual inspection and direct measurement on computerized tomography (CT) in individuals with branchio-oto-renal syndrome (BOR). We ask if it is possible for the untrained observer to use a battery of CT observations as a tool in the overall evaluation of the BOR phenotype. STUDY DESIGN: Retrospective evaluation of CT findings in individuals with a clinical diagnosis of BOR based on criteria derived from genotype-phenotype analyses. METHODS: Prospective measurement of temporal bone CT imaging in 21 individuals (42 ears) with BOR and 21 normally hearing controls (21 ears) was performed. Thirty-nine aspects of each temporal bone were evaluated: 17 by direct measurement, 5 computed from direct measurement, and 17 by visual inspection. Thirty-eight recordings from each ear were made on axial section and 1 was made on coronal section. RESULTS: Statistically significant differences were found between BOR and control groups in 30 of 39 categories (76.9%). The most common and easily identifiable characteristics of BOR by visual inspection were 1) hypoplastic apical turn of the cochlea, 2) facial nerve deviated to the medial side of the cochlea, 3) funnel-shaped internal auditory canal, and 4) patulous eustachian tube. The embryological origin of temporal bone anomalies in BOR are described. CONCLUSIONS: CT evaluation of the temporal bone, when properly investigated, should be used as an important tool in the overall evaluation of the BOR phenotype.

Adolescent↗

PubMed2004

Intracranial involvement in extramedullary hematopoiesis: case report and review of the literature.

Intracranial involvement in extramedullary hematopoiesis (EMH) is rare, but it should be suspected in patients with myelofibrosis presenting with chronic severe headache. We present a 9-year-old girl with known myelofibrosis whose headaches were unresponsive to routine treatment. CT and MRI studies of the brain showed diffuse pachymeningeal thickening. CT examinations of the chest and abdomen had demonstrated bilateral thoracic paraspinal masses caused by EMH, suggesting the possibility that the intracranial involvement might also be related to EMH. The diagnosis was confirmed by sulfur colloid isotope scan.

Brain Diseases↗

PubMed2004

Morning glory disc anomaly, midline cranial defects and abnormal carotid circulation: an association worth looking for.

We report on a 4-year-old boy who presented to the ophthalmology department for assessment of convergent strabismus. Ophthalmic examination showed a left morning glory optic disc anomaly and retinal detachment. Plain films obtained for investigation of short stature prior to ophthalmic examination revealed delayed bone age. Ophthalmological findings prompted CT and MRI imaging and angiographic investigations. Midline cranial defects and abnormal carotid circulation were identified. These findings may be associated with morning glory optic disc anomaly, and their association is often under-recognized. It is important that clinicians and radiologists be aware of this spectrum of disorders, as the vascular abnormalities may predispose the patient to transient ischemic attacks and strokes. Growth delay may result from hypopituitarism.

Bone Development↗