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Biomedical subjects

D G McLone

Publications and source records attributed to D G McLone.

At least 19 recordsLinked to original sources
PubMed1992

Anatomical progression of the Chiari II malformation.

To evaluate whether anatomic change of the relationship of the Chiari II malformation and the cranial base was occurring, 22 children with meningomyelocele had serial MRI scans reviewed. A ratio (B/A) was established between the distance from the foramen magnum to the caudalmost portion of herniated cerebellum (B) and the diameter of the foramen magnum (A) and this ratio was compared on serial MRI scans. Eighteen children had an increase in the B/A ratio, two children had a decrease, and two had no change. This indicates that continuous anatomic change of the Chiari II malformation and the skull base is occurring. Clinical deterioration in the older child may be explained by a combination of compressive and traction forces due to this change.

Arnold-Chiari Malformation↗
PubMed1991

Ultrastructural alterations in the aqueous outflow pathway of adult buphthalmic rabbits.

The aqueous outflow pathway of adult rabbit eyes with congenital glaucoma (buphthalmos) was examined by light microscopy and by scanning and transmission electron microscopy. The morphology of the buphthalmic rabbit aqueous outflow pathway was markedly abnormal when examined at 6 months, 1 yr, and 2 yr displaying apparent loss and/or compression of the iris pillars, dilation of the intertrabecular spaces, loss of endothelial cell-to-cell association and disorganization of trabecular lamellae, and posterior displacement of the aqueous plexus. In addition, the trabecular meshwork lamellae were observed only adjacent to the sclera and the inner portion of the trabecular meshwork was limited to swirls of collagen with scattered cells. These morphological findings suggest that the disease process in the rabbit principally involves an alteration in the differentiation and maintenance of the structural integrity of the trabecular meshwork. The loss of structural support of the buphthalmic trabecular meshwork may be a factor in the wide variation in intraocular pressure and may allow for compression of the trabecular meshwork against the aqueous plexus.

Animals↗
PubMed1991

Occipital meningoceles in patients with the Dandy-Walker syndrome.

Occipital cephaloceles in the Dandy-Walker syndrome are not rare. To date, 28 cases have been reported. We report on 8 cases of associated occipital meningocele, totalling 16% of all patients with the Dandy-Walker syndrome in our series. In all patients, communication existed between the posterior fossa cyst and the occipital meningocele. In 2 patients, the occipital meningocele disappeared after cerebrospinal fluid shunting and never required surgical repair. It appears that the cranial defect had ossified and resulted in self-closure. Poor intellectual development in persons with the Dandy-Walker syndrome is associated with the presence of other central nervous system and systemic abnormalities and not with occipital meningoceles alone.

Cerebrospinal Fluid Shunts↗
PubMed1991

Developmental disorders of the pediatric spine.

Developmental disorders of the pediatric spine are a group of congenital malformations commonly referred to as spinal dysraphism. These malformations are characterized by incomplete or absent fusion of midline mesenchymal, bony, and neural structures. They can be classified according to the presence or absence of an associated back mass. A detailed analysis of the embryology, clinical findings, and radiologic characteristics of the common forms of spinal dysraphism is outlined.

Humans↗
PubMed1990

Medulloblastomas in childhood: postsurgical evaluation with myelography and cerebrospinal fluid cytology.

Thirty-one children with medulloblastoma treated at the Children's Memorial Hospital have been evaluated with both postoperative myelography and cerebrospinal fluid (CSF) cytological studies. Computed tomography of the spine following myelography was used in an attempt to increase sensitivity. Each study was done 30 days after radical resection of the posterior fossa tumor, and just prior to the spinal irradiation. Only 3 (9.6%) showed positive results for spinal subarachnoid seeding by both myelography and CSF cytology. In 2 of these patients, preoperative head CT showed evidence of intracranial subarachnoid seedings. The incidence of positive myelographic finding in our series is lower than reported ones, and neoplastic cells are detected in the CSF only when the myelography shows visible disease.

Adolescent↗
PubMed1990

Intelligence and achievement in children with myelomeningocele.

Intelligence and achievement test scores for 89 children with myelomeningocele (MM), ages 4 to 14 years, were obtained from medical records. These children scored below the population average but within the normal range on most tests. The greatest deficits occurred on Performance IQ, arithmetic achievement, and visual-motor integration (copying geometric designs). With increasing age, these children fell further behind age-peers on tests of arithmetic and visual-motor performance while keeping pace on reading and spelling tests. We speculate that these findings may reflect a developmental difference between MM children and nonhandicapped children in a visual-perceptual-organizational cognitive function such as Rourke (1987) has proposed.

Achievement↗
PubMed1989

Spina bifida today: problems adults face.

Late deterioration is common in patients with a myelodysplasia. Most, possibly all, of this deterioration is preventable or correctable. It is not simply the natural history of the disease. Only through close follow-up by trained observers can these problems be anticipated and discovered early. Regularly scheduled evaluations of intellectual, musculoskeletal, and urinary systems are essential. When the clinician is familiar with the signs and symptoms of the various causes of deterioration and armed with ultrasound, myelography, CT, and MRI, the most likely cause can be identified and a treatment plan outlined.

Adult↗
PubMed1989

The cause of Chiari II malformation: a unified theory.

The cause of the Chiari II hindbrain deformity in children born with a myelomeningocele can be explained by the lack of distention of the embryonic ventricular system. Defective occlusion and an open neural tube precludes the accumulation of fluid and pressure within the cranial vesicles. This distention is critical to normal brain development. The small posterior fossa, cerebral disorganization, and lückenschädel are the result.

Animals↗
PubMed1989

Paraplegia resulting from thoracolumbar stenosis in a seven-month-old achondroplastic dwarf.

In young achondroplastic children, neurological manifestations have been found to include macrocephaly, hydrocephalus or ventriculomegaly and cervicomedullary compression. Occasionally in the second decade, lumbar radiculopathy or paraparesis resulting from severe thoracolumbar kyphosis develops. In this paper, we report the unique case of an achondroplastic dwarf who developed paraplegia due to thoracolumbar spinal cord compression at the age of 7 months. Compromise of the spinal canal was found to be due not to bony stenosis, but to a second layer of fibrous tissue, histologically identical to the dura. Treatment consisting of decompressive laminectomy and resection of the constricting tissue allowed the child to recover completely. Clinical, radiographic and pathological findings are discussed.

Achondroplasia↗
PubMed1989

Prognostic importance of DNA ploidy in medulloblastoma of childhood.

The deoxyribonucleic acid (DNA) content of 53 medulloblastomas was analyzed by means of flow cytometry and compared with the clinical and histological findings in the host patients. Analysis of DNA showed that about half of the tumors were diploid and the other half were aneuploid. More diploid tumors were found among patients of a young age, but the difference was without statistical significance. Cellular differentiation of the tumor did not correlate with DNA ploidy. No correlation was found between Chang's T staging system and the DNA ploidy, whereas the M staging correlated with the ploidy; diploid medulloblastomas had a greater tendency to metastasize than aneuploid medulloblastomas (p = 0.0003). Four-year survival was compared with the extent of resection and DNA ploidy. The patients with total resection and aneuploid medulloblastoma had a better prognosis than those with subtotal resection and diploid tumor (p = 0.001). There was only one survivor among eight patients with subtotally resected diploid medulloblastomas, while all of the seven patients with totally resected aneuploid medulloblastomas survived. Comparison of the G0/G1 phase fraction and S phase fraction in the surviving group and the deceased group offered no significant information.

Adolescent↗
PubMed1989

The perinatal management of central nervous system anomalies.

The diagnosis, proper evaluation, and treatment of a CNS anomaly requires the participation of many subspecialists and support personnel. The outcome can be favorably modified through the choice of elective termination, aggressive or passive perinatal intervention, and the 24-hour availability of neurosurgical expertise. At the conclusion of the pregnancy, accurate and informative counseling also should be provided. Although these discussions need not take place immediately, review of the final diagnosis, its risk of recurrence, and the appropriate screening for subsequent pregnancy should be included.

Central Nervous System↗
PubMed1988

Flow cytometric DNA analysis of medulloblastoma. Prognostic implication of aneuploidy.

Paraffin-embedded surgical specimens from 26 infants and children with medulloblastomas treated between 1972 and 1981 were examined for DNA ploidy by flow cytometry (FCM). All patients received a standard treatment (a combination of maximum debulking of medulloblastoma and postoperative craniospinal irradiation with a posterior fossa boost of 5000 rad or more). They were studied to correlate the results of the findings of FCM DNA analysis with their final outcome, DNA ploidy, and extent of tumor resection. All seven patients with totally resected aneuploid medulloblastoma are alive, whereas only one of six patients with subtotally resected diploid medulloblastoma is alive (P = 0.0047). The current study suggests both DNA ploidy and extent of surgical resection are the most important determinant of patients' prognosis. Patients in selected group, particularly those with subtotally resected diploid tumor, are advised to undergo aggressive adjuvant chemotherapy.

Adolescent↗
PubMed1988

Cerebral primitive neuroectodermal tumors in childhood.

A series of 17 infants and children with cerebral primitive neuroectodermal tumors (PNETs) detected by computed tomography is presented. The pertinent literature is reviewed. Because of ongoing nosological difficulty, we include in this series only those tumors which are located in the cerebral hemisphere, and are composed of predominantly undifferentiated neuroepithelial tumor with or without glial or neuronal differentiation. The prognosis of the patients with cerebral PNETs remains poor despite treatment including surgical resection, radiation therapy and/or chemotherapy. Only two patients had a long term survival more than 4 years in this series. The histological features and the extent of surgical resection did not influence the patients survival. Nevertheless, visible total resection afforded better control of local disease of the primary site, but remote metastases along the cerebrospinal fluid pathway were frequent at relapse. The patients with cerebral PNETs appear to be best treated with radical gross total resection, postoperative radiation therapy including irradiation to the neuraxis and aggressive chemotherapy.

Adolescent↗
PubMed1988

Head injuries in children under 36 months of age. Demography and outcome.

Head injuries in children under the age of 3 years have not been extensively studied, due in part to the lack of an objective tool for neurological assessment. We have developed a Children's Coma Scale (CCS) by modifying the verbal response subscore of the Glasgow Coma Scale (GCS) to overcome this limitation. When applied prospectively to children under 3 years of age, we found the CCS to be useful in predicting outcome. During the 5-year study period from 1981 to 1985, there were 738 patients with head injuries (0-16 years) admitted to the Children's Memorial Hospital in Chicago, including 318 (43.1%) less than 3 years of age. Initial data demonstrated the following observations. The most common mechanism of injury was a fall (75.5%). Although a brief loss of consciousness (LOC) was reported in three-fourths of the patients, prolonged LOC of more than 6 h was uncommon (16/318, 5.0%). The classically described "lucid interval" was seen in only 7 children (2.2%) and was not a reliable indicator of epidural hematoma. Post-traumatic seizures developed more commonly in children under 2 years of age (15.7%) than in older children (11.6% under 3 years of age, 9.6%, entire group), (P less than 0.001). Oculovestibular reflex and bilateral fixed dilated pupils had the most reliable correlation with outcome. Other brain-stem reflexes were less useful.(ABSTRACT TRUNCATED AT 250 WORDS)

Cause of Death↗
PubMed1988

Anorectal malformations: evaluation of associated spinal dysraphic syndromes.

The early recognition and treatment of correctable lesions of the terminal spinal cord in patients with anorectal malformations may preserve important neurologic function. Tethered cord and intraspinal masses are detectable with the use of high-resolution ultrasonography in the neonate. Fourteen infants and children with anorectal malformations and associated spinal dysraphism have been identified in our institution over the past 7 years. Six patients had cloacal exstrophy, and eight had imperforate anus (four high and four low lesions). The spinal lesions caused symptoms in only seven children; progressive neurologic deficit in five, and urinary incontinence or retention in two others. Five asymptomatic patients with cutaneous abnormalities on the back were studied and two were discovered during scoliosis evaluation. Imaging techniques included high-resolution ultrasonography, computed tomography with and without metrizamide myelography, and magnetic resonance imaging. Spinal sonography was highly accurate in the neonatal period. The application of ultrasonography can be of great advantage in early screening of patients with anorectal malformations and, in some cases, may eliminate the need for invasive imaging techniques.

Anus, Imperforate↗
PubMed1988

The urological manifestations of the tethered spinal cord.

The tethered spinal cord is an entity with potentially grave neurourological implications. Presenting urological symptoms include incontinence, symptomatic urinary tract infections and stool soiling. These symptoms may be the first to herald a tethered cord. The patients with previously repaired myelodysplastic defects are particularly prone to development of this lesion. We correlated urological history with preoperative and postoperative cystometry in 20 myelodysplastic children. In this study we noted that clinical symptomatology and urodynamic parameters improved in 60 per cent of those children who underwent cord untethering. A better result was evident in children whose condition was repaired promptly.

Fecal Incontinence↗