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Biomedical subjects

S Blaser

Publications and source records attributed to S Blaser.

52 records · Page 3Linked to original sources
PubMed1995

Absence of the greater sphenoid wing in neurofibromatosis type I: congenital or acquired: case report.

unilateral absence of the greater wing of the sphenoid bone is a distinctive but uncommon manifestation of Type I neurofibromatosis, which has until now been regarded as a developmental anomaly of mesodermal origin. A computed tomographic scan was obtained in a 4-week-old infant with an abnormal left eye. The scan demonstrated an intact ipsilateral sphenoid bone, except for minor expansion of the medial end of the left superior orbital fissure. Another computed tomographic scan was obtained 6 years later, when the child had café-au-lait patches, axillary freckling, Lisch nodules, and left phthisis bulbi. This later scan showed typical sphenoid dysplasia. Much of the greater wing was absent, and the anterior temporal pole was displaced anteriorly. In this article, we discuss the implications of this case in terms of the cause of this condition and the diagnosis of Type I neurofibromatosis.

Eye Abnormalities↗
PubMed1994

A case of unilateral congenitally enlarged extraocular muscles.

BACKGROUND: Enlargement of extraocular muscles is an uncommon finding in children. Little has been written in the literature about possible causes. METHODS: The authors present the clinical findings of a young girl who had unilateral congenitally enlarged extraocular muscles at 8 months of age. She underwent computed tomography (CT) and magnetic resonance imaging (MRI) scans, systemic assessment, and extraocular muscle biopsy to determine a cause for the enlarged muscles. RESULTS: The patient had a unilateral left esotropia and hypotropia at birth that was nonprogressive. High-resolution CT and MRI scans showed enlargement of the left inferior rectus, lateral rectus, and medial rectus muscles. Strabismus surgery undertaken at 2 years of age showed that the affected muscles were restricted on forced duction testing but were macroscopically normal in appearance. A biopsy specimen of the left lateral rectus muscle was processed for histologic, histochemical, and electron microscopic studies, but no abnormal pathologic findings were found. CONCLUSION: This patient's constellation of findings appears to be unique: it does not follow any previously reported pattern of disorders of extraocular muscle enlargement.

Biopsy↗
PubMed1993

Primary leptomeningeal melanoma: an unusually aggressive tumor in childhood.

Primary malignant melanoma of the leptomeninges of the central nervous system is a rare and aggressive tumor in children. We report our experience from 1964 to 1990 with this tumor in eight children. The mean age at diagnosis was 4.9 years (range, 1.3 to 13 yr). Five children presented with signs and symptoms of raised intracranial pressure from hydrocephalus secondary to tumoral obliteration of the basal cisterns, but the time from the initial symptomatology to diagnosis was frequently delayed. Three patients in this series had hairy nevi in association with their leptomeningeal melanoma. Cerebrospinal fluid (CSF) analysis typically showed raised opening pressures, decreased glucose, and increased protein concentrations. Malignant melanoma cells were found in the CSF in three patients. Confirmatory radiographic examinations included air encephalography, myelography, and computed tomographic and magnetic resonance scanning. Four patients were treated with lumboperitoneal shunts, and one patient was treated with a ventriculoperitoneal shunt for hydrocephalus. Two patients underwent craniotomies and subtotal excisions of their tumors. In seven patients, a definitive diagnosis of leptomeningeal melanoma was made by pathological examination of tissues sent at surgery or at post mortem. In one case, the diagnosis was established by a detailed cytological analysis of the CSF. Four children died of fulminant disease and tumor spread before treatment could be instituted. The four children who received treatment had a combination of radiation therapy and chemotherapy. One child received intrathecal methotrexate. The two children with the longest survivals (2 and 3 yr, respectively) received cisplatinum and dimethyltriazenoimidazole carboxamide in addition to craniospinal irradiation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Pediatric spinal neoplasms.

Magnetic resonance imaging (MRI) is an accurate and noninvasive tool in the evaluation of children with spinal neoplasm. Localization and definition of site and extent of disease for treatment planning, the most important goals of neuroimaging in spinal neoplastic disease, have become more precise with MRI, because all spinal compartments can be seen without the need for subarachnoid puncture. Epidural and contiguous soft tissue disease, and associated vertebral abnormalities such as marrow replacement by metastatic processes, are readily confirmed during the same examination. In children, as in adults, gadolinium-diethylenetriaminepentaacetic acid aids in separating intramedullary neoplasms from associated edema or syrinx, and is essential in the evaluation of intradural-extramedullary spread of neoplasm. MRI is also useful in the exclusion of compressive lesions in children with systemic neoplasms and cord infarction or treatment-related transverse myelopathy.

Adolescent↗
PubMed1992

Magnetic resonance imaging evaluation of delayed myelination in Down syndrome: a case report and review of the literature.

Magnetic resonance imaging has been found to be useful in assessing brain myelination and provides information on brain maturation. The normal pattern of brain myelination conforms to a fixed sequence, with good pathologic and MRI correlation. Neuropathologic analysis of myelination has shown delayed central myelination in Down syndrome. Delayed myelination on MRI in Down syndrome has not previously been reported. We report a case of Down syndrome with a significant delay in myelination as demonstrated on MRI. This 18-month-old infant had brain myelination equivalent to that expected for an 11-month-old infant. To determine the relative incidence, extent of delayed myelination, and time for recovery to full myelination in Down syndrome, more cases require examination and assessment. Magnetic resonance imaging has the advantage of serial assessment of myelination during brain maturation.

Brain↗
PubMedDate not supplied

Focal cortical dysplasia in children with localization-related epilepsy: EEG, MRI, and SPECT findings.

A retrospective analysis was conducted of 9 children with focal cortical dysplasia and localization-related epilepsy who underwent epilepsy surgery. Focal cortical dysplasia includes malformed lesions with extensive abnormalities of neuronal morphology, architecture, and lamination. The patients were examined by EEG and video EEG telemetry, CT, MRI, and SPECT using 99mTc-HmPAO. EEG disclosed interictal localized epileptiform activity in 8 patients and nonepileptiform activity with slow waves in 1. Ictal EEG telemetry demonstrated a predominantly localized seizure onset in 8 patients and MRI demonstrated an abnormal loss of gray and white matter distinction in 6. Decreased regional cerebral blood flow (rCBF) was detected in 4 patients by interictal SPECT, and increased rCBF in the same epileptogenic focus in 2 by postictal SPECT. Pathologic analysis found focal cortical dysplasia in 8 patients. One had extensive focal polymicrogyria, pachygyria, and extensive white matter heterotopias. It is concluded that MRI can detect focal cortical dysplasia, which corresponds to the epileptogenic focus on EEG, and SPECT may help to detect a functional abnormality in the same region.

Adolescent↗
PubMedDate not supplied

MR imaging with Gd-DTPA in leptomeningeal spread of lymphoma.

We describe the magnetic resonance (MR) plus Gd-diethylenetriamine pentaacetic acid (DTPA) findings in a patient with leptomeningeal spread of lymphoma. Gadolinium-DTPA aided in the diagnosis by offering additional information after noncontrast MR. Magnetic resonance with Gd-DTPA may well prove to be an important adjunct in the work-up of patients suspected of leptomeningeal spread of neoplasm.

Aged↗
PubMedDate not supplied

MR evaluation of the temporomandibular joint in juvenile rheumatoid arthritis.

Temporomandibular joint (TMJ) disease is uncommon in children but frequently occurs in juvenile rheumatoid arthritis (JRA). Involvement is often asymptomatic; however, it can lead to growth disturbances and facial deformity. Thirty TMJs in 15 children (11 girls and 4 boys aged 3.5-18 years) with JRA were evaluated clinically and by MRI. Plain films were reviewed when available. Magnetic resonance imaging parameters included T1-weighted and in some cases T2-weighted or gradient recall echo sequences. We assessed condylar configuration, glenoid fossa changes, presence of erosions, disk abnormality, range of motion, and presence of joint effusions or pannus. Abnormalities included cortical erosions (n = 19), disk thinning (n = 18), and perforation (n = 2). Reduction of joint movement (n = 20), joint locking (n = 3), and pannus/effusions (n = 5) were also found. Magnetic resonance imaging is a useful technique for the detection of TMJ involvement in JRA. Early detection and therapeutic intervention may lessen or prevent subsequent deformities.

Adolescent↗
PubMedDate not supplied

Pathology of chronic herpes infection associated with seizure disorder: a report of two cases with tissue detection of herpes simplex virus 1 by the polymerase chain reaction.

Although uncommon, the association of chronic encephalitis with epilepsy is well recognized. While a viral etiology has been suspected based on the morphology, to date no virus has been successfully cultured from the brain in patients with Rasmussen's encephalitis. We describe the pathologic findings and report the detection of herpes simplex virus 1 (HSV1) in the brain in two patients who presented primarily with intractable seizures. In the first patient, an intrauterine infection was suspected as the underlying basis for the seizure disorder and the extensive cerebral calcification and gliosis. The second patient (with presumed HSV1 encephalitis at age 7 months) underwent a temporal lobectomy for medically refractory seizures at the age of 3 years and pathologic examination revealed a chronic encephalitis. While immunohistochemical, ultrastructural, and culture studies were negative for viral pathogens, molecular analysis by the polymerase chain reaction (PCR) revealed HSV1 DNA sequences in both cases. Thus our cases represent two examples of chronic encephalitis associated with a seizure disorder, where a definitive viral etiology was documented by PCR.

Calcinosis↗
PubMedDate not supplied

Optic pathway glioma: correlation of imaging findings with the presence of neurofibromatosis.

BACKGROUND AND PURPOSE: Despite the benign histology of optic pathway glioma (OPG) (low-grade astrocytoma), its biological behavior is unpredictable, and it is unclear whether specific morphologic or anatomic patterns may be predictive of prognosis. It is also unclear whether OPG associated with neurofibromatosis (NF) is a distinct entity from non-NF-OPG. Our purpose was to describe the MR imaging features of OPG, compare the findings between patients with and those without NF, and identify prognostic imaging signs. METHODS: MR examinations of 91 patients with OPG (47 with NF and 44 without) were reviewed at presentation and during follow-up. The images were evaluated for size and extension of tumor, and imaging parameters. Statistical bivariate analysis was used to compare the patients with and those without NF, and Pearson correlation was used to evaluate the correlation between the different imaging parameters and prognosis. Kappa values were calculated to determine intraobserver and interobserver variability. RESULTS: The most common site of involvement in the NF group was the orbital nerve (66%), followed by the chiasm (62%). In the non-NF group, the chiasm was the most common site of involvement (91%); the orbital nerves were involved in only 32%. Extension beyond the optic pathway at diagnosis was uncommon in the NF group (2%) but frequent in the non-NF group (68%). In the NF group, the tumor was smaller and the original shape of the optic pathways was preserved (91% vs. 27% in the non-NF group). The presence of cystic components was significantly more common in the non-NF patients (66% vs. 9% in the NF group). During follow-up, half the NF patients remained stable, in contrast to 5% of the non-NF group. No statistical correlation was found between imaging features and biological behavior of the tumor. CONCLUSION: NF-OPG is a separate entity from non-NF-OPG, with different imaging features and prognosis, thereby warranting a specific diagnostic, clinical, and therapeutic approach.

Adolescent↗
PubMedDate not supplied

Gd-DTPA enhancement of posterior epidural scar: an experimental model.

Because of the tremendous clinical and physiological importance of anterior epidural scar, an easily produced and reproducible model to assess potential pathways for lessening its formation is a necessity. We speculated whether posterior epidural scar (produced by the less complex surgery of laminectomy alone) could be considered equivalent to anterior scar from an imaging standpoint; that is, enhancement following Gd-DTPA irrespective of scar age. Posterior epidural scar in dogs showed the highest degree of enhancement 1 month after surgery, with a rapid decline thereafter out to 4 months postsurgery to a level equivalent to that of paraspinal muscle. Gd-153-DTPA time/activity curves paralleled the Gd-DTPA findings. Light microscopy showed granulation tissue after 1 month, and mature scar with large amounts of collagen 4 months after surgery. Electron microscopy showed tight capillary endothelial junctions. An appropriate model for epidural scar, which has imaging characteristics similar to human anterior scar, necessitates an extensive lumbar laminectomy with anterior epidural dissection. A simple laminectomy, while easily performed, does not provide a physiologically correct time course of enhancement.

Animals↗
PubMedDate not supplied

Spontaneous regression of a tectal mass in neurofibromatosis 1.

MR images showed an enhancing, enlarging mass in the tectum of the midbrain in a child with neurofibromatosis type 1. The mass was presumed to be a tectal glioma, which initially enlarged then regressed in size over a 3-year period and ceased to enhance. Although a tissue diagnosis was not available, we believe the temporal evolution of this lesion is strong presumptive evidence of a hamartoma. This case argues for the conservative management of patients with neurofibromatosis type 1 when possible.

Adolescent↗