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Biomedical subjects

J G McComb

Publications and source records attributed to J G McComb.

At least 109 records · Page 6Linked to original sources
PubMed1986

Intracranial arterial aneurysms in childhood: more recent considerations.

Nineteen children with congenital, mycotic, traumatic and tumoral arterial aneurysms were studied neuroradiologically. The important role of computed tomography (CT) was shown in two traumatic aneurysm cases where bleeding was clinically inapparent. Among the unique cases described was a boy with a pituitary tumor in whom an aneurysm was discovered incidentally; coexistence of these lesions in childhood has not been documented previously. Nor has a tumoral aneurysm been mentioned (the case reported had a surrounding primary anaplastic sarcoma). Rare cases included a cavernous carotid mycotic aneurysm and infants with hemorrhage from congenital distal middle cerebral artery aneurysms. Marked cellular responses within the aneurysm walls, believed to be a reaction to hemorrhage, were noted in both infants.

Adolescent↗
PubMed1986

Ultrastructural morphology of the olfactory pathway for cerebrospinal fluid drainage in the rabbit.

Previous physiological studies indicate that the olfactory region serves as a major pathway for cerebrospinal fluid (CSF) drainage into the lymphatic system. The present study was undertaken to determine the ultrastructural characteristics of this egress route. New Zealand White rabbits received a single bolus injection of the tracer ferritin (MW 400,000) into both lateral ventricles in such a manner as not to raise the intraventricular pressure above the normal level. The animals were sacrificed via intracardiac perfusion of fixative between less than 12 minutes and 4 hours following injection. The cribriform region was removed en bloc, decalcified, sectioned coronally, and prepared for light and electron microscopic examination. The arachnoid, dura, and periosteum surrounding the fila olfactoria passing through the cribriform plate merge together and form the perineurium, which consists of multiple layers of loosely overlapping cells with widely separated junctions and few vesicles. The perineurium surrounding the olfactory filaments at the superficial submucosal level is only one cell thick. The subarachnoid space freely communicates with the perineural space surrounding each filament. No morphological barrier between the perineural space and the loose submucosal connective tissue was identified. Whether or not the perineurium was multi- or single-layered, ferritin was noted in abundance between the loosely overlapping perineural cells and in the submucosal connective tissue. The distribution of ferritin at 12 minutes was similar to that at 4 hours; however, the quantity of ferritin was increased at 4 hours. These results indicate that no significant barrier to CSF drainage is present at the rabbit cribriform region and that CSF reaches the submucosal region rapidly via open pathways.

Animals↗
PubMed1985

Intraorbital cerebrospinal fluid outflow and the posterior uveal compartment of the hamster eye.

An ultrastructural and tracer study was undertaken to determine normal outflow pathways of cerebrospinal fluid (CSF) at the terminal subarachnoid space (SAS) of the optic nerve. In the morphological studies, the optic nerve dura and arachnoid were found to be continuous with the sclera of the eye beyond the optic nerve SAS. The pia mater is continuous with the inner sclera and the lamina fusca of the eye. Montages and serial sections demonstrated that the distal SAS is divided into numerous tortuous channels to form an "arachnoidal trabecular meshwork". Spaces of this meshwork continue into "microcanals" which bypass the outer arachnoid barrier layers of the optic nerve meninges to reach the sclera and posterior intraorbital connective tissue. Ferritin infused into the cisterna magna entered the optic nerve SAS within 1 min and reached arachnoidal trabecular meshwork channels and the microcanals within 8 min. It then passed into intraorbital connective tissue spaces at the posterior pole of the eye. Ferritin appeared to be blocked by the lamina fusca and a newly discovered "posterior compact zone" which together prevented its entrance into the choroidal interstitium. These observations suggest that a "subarachnoidal-scleral-orbital outflow pathway" provides a route for CSF drainage from the optic nerve SAS to intraorbital connective tissue. The previously described "posterior uveal compartment" in the hamster eye (Kelly et al. 1983) appears to be relatively isolated from this subarachnoidal-scleral-orbital CSF outflow.

Animals↗
PubMed1985

Neuropsychological outcome after severe pediatric near-drowning.

Between April 1979 and August 1983, 49 nearly drowned children in serious condition were admitted to Childrens Hospital of Los Angeles (CHLA) with Glasgow coma scores of 3, 4, or 5 and underwent intracranial pressure monitoring and brain resuscitative therapy. Of the 49 patients, 29 (59%) died in the hospital 1 day to 3 months after admission, 13 (27%) were discharged in vegetative states, and 7 (14%) made good recoveries. No patient made a partial neurological recovery. The sustained mean highest intracranial pressure was significantly higher and the sustained lowest cerebral perfusion pressure was significantly lower for those who died than for survivors (P less than 0.05), but these data did not significantly distinguish between intact and vegetative survivors. Pupillary reactivity noted on arrival at CHLA also significantly discriminated survivors and fatalities (P less than 0.05), but not between intact and vegetative survivors. The presence of any motor activity after arrival at CHLA, even posturing or twitching, indicated a significant chance for intact survival (P less than 0.05), although such activity did not discriminate between death and vegetative survival. Extensive neuropsychological testing indicated that the apparently intact recovered patients generally showed nearly average levels of cognitive functioning, with mild residual gross motor and coordination deficits.

Adolescent↗
PubMed1983

Chronic spinal epidural hematoma in hemophilia A in a child.

A case of chronic spinal epidural hematoma in a thirteen-year-old male, subsequently found to have hemophilia A is reported. Following myelography, surgery was undertaken with clotting factor replacement with relief of cord compression. The patient made an uneventful recovery.

Adolescent↗
PubMed1983

Computed tomography of posterior fossa ependymomas in childhood.

In reviewing 10 children with surgically proven posterior fossa ependymomas, various computed tomographic representations were seen. Calcification, seen in 50% of the cases, was the single most important finding suggesting the diagnosis of ependymoma. The appearance of two of our ependymomas mimicked the "typical" appearance of medulloblastomas. A case of calcified brainstem ependymoma is presented, to our knowledge, the first such case studied with computed tomography.

Adolescent↗
PubMed1983

Brief clinical communication: neurogenic perineal prolapse in neonates.

Disturbed innervation of the pelvic muscular diaphragm from lumbosacral myelodysplasia and other osseous dysplasias results in flaccid paralysis of the perineum. This permits excessive downward herniation, most noticeable in neonates, of the lower abdominal and pelvic organs. The radiographic changes occurring with organ descensus may be transitory and diverse, and recognition of these various findings is important to avoid misdiagnosis and unnecessary further investigations. Several examples of the radiographic changes are presented.

Bone Diseases, Developmental↗
PubMed1983

Management of hydrocephalus secondary to intraventricular hemorrhage in the preterm infant with a subcutaneous ventricular catheter reservoir.

To control hydrocephalus resulting from massive intraventricular hemorrhage in premature neonates with respiratory distress syndrome, we inserted a specially designed low profile subcutaneous ventricular catheter reservoir (reservoir) by the 12th day of life (average; range, 3 to 30 days) in 20 neonates whose mean birth weight was 1110 +/- 270 g (28.7 +/- 1.6 weeks of gestation). The reservoir was repeatedly aspirated over 10 to 48 days. No cerebrospinal fluid infection, reservoir obstruction, or breakdown of the skin overlying the reservoir occurred. Serial computed tomographic scans documented control of the hydrocephalus and an increase in the thickness of the cortical mantle of the survivors. No mortality was associated with placement of the reservoir or its subsequent conversion, if necessary, to a ventriculoperitoneal shunt. However, only 7 of the 20 infants survived. On follow-up 3 to 5 years later, 2 of the 7 have normal intellectual and motor development. Two infants are normal intellectually, but have a motor deficit. The remaining 3 patients have both significant intellectual and motor developmental delay. The use of the reservoir is offered as a safe and effective alternative to repeated ventricular punctures, external ventricular drainage, or initial shunting. Aggressive management of hydrocephalus secondary to intraventricular hemorrhage may improve neurological function in some surviving neonates.

Brain↗
PubMed1982

Computed tomographic observations pertinent to intracranial venous thrombotic and occlusive disease in childhood. State of the art, some new data, and hypotheses.

Selected topics are discussed and new observations recorded regarding computed tomographic (CT) evaluation of intracranial venous thrombotic and occlusive disease in childhood. High density of the vein of Galen and adjacent venous sinuses (relative to brain) can be seen normally in children. A number of potential pitfalls in the diagnosis of superior sagittal sinus thrombosis are also disclosed. A case of cavernous sinus thrombosis with abnormal CT changes in included. In addition, the normal CT appearance of the cavernous sinus is described. In some cases, filling defects occur which appear to correlate with normal cranial nerves. An unusual case of venous sinus occlusion by neoplasm (sarcoma) is presented. Finally, new findings in the Sturge-Weber syndrome are analyzed. Enhancement of the brain in this condition may have its basis in altered circulation resulting from fundamental venous abnormalities.

Adolescent↗
PubMed1982

Cerebrospinal fluid drainage as influenced by ventricular pressure in the rabbit.

Artificial cerebrospinal fluid (CSF) containing radioisotope iodinated (125I) serum albumin (RISA) and either blue dextran or indigo carmine was given to white New Zealand rabbits over 4 hours. In one group it was given by ventriculocisternal perfusion, in one by ventricular infusion, and in one by cisterna magna infusion. Blood was sampled continuously from the superior sagittal sinus (SSS) or intermittently from the systemic arterial circulation. Removal of CSF from the cisterna magna during the ventriculocisternal perfusion kept the intracranial pressure (ICP) at 0 to 5 torr, whereas ventricular or cisterna magna infusion raised the ICP to 20 to 30 torr and 15 to 20 torr, respectively. In the two groups with raised ICP, an increased concentration of RISA was present in the optic nerves, olfactory bulbs, episcleral tissue, and deep cervical lymph nodes; but this was not found in the group with normal ICP. In all three groups, the concentration of RISA in the SSS blood was the same as in the systemic arterial blood. The concentration gradient of RISA across the cerebral cortex was similar in both the ventriculocisternal perfusion and the ventricular infusion groups. With cisterna magna infusion, the concentration of RISA was the same on the cortical surface and less in the ventricles compared with the ventricular infusion. It is concluded that, with elevated ICP, CSF drained via pathways that are less evident under normal pressure. Drainage of CSF was similar irrespective of whether the infusion site was the ventricles or cisterna magna. It did not appear that acute dilatation of the ventricles during ventricular infusion compromised the subarachnoid space over the surface of the hemisphere, as the concentration of RISA on the convexities and in the SSS blood did not significantly differ between the groups. Transcortical bulk transfer of CSF was not evident with raised ICP.

Animals↗
PubMed1981

Lipomas of the corpus callosum associated with frontal dysraphism.

Using computed tomography (CT), we have been able to identify the combined occurrence of lipoma of the corpus callosum and dysraphic lesions associated with frontal bone defects in two cases. In one case, there was a true encephalocele, and in the other case a lipoma with cartilaginous tissue was present. Such combinations are very rare; thus, the impetus to report these cases. The disorganization of the central nervous system was extensive in the first infant and was associated with profound developmental delay, while the second infant had much less anatomical abnormality, and development to date is normal. Bony defects (on skull films), typical appearances of lipoma of the corpus callosum, and characteristics of the dysraphic lesions (on CT) were seen. Angiography was obtained in the infant with a true encephalocele.

Abnormalities, Multiple↗
PubMed1981

Cortical damage from Zenker's solution applied to the dura mater.

An experimental and clinical study was undertaken to determine whether Zenker's solution without glacial acetic acid (modified Zenker's solution) applied to the external surface of the dura mater can penetrate to injure the underlying cortex. Adult cats and dogs, the dura of which had an average thickness of 0.2 and 0.25 mm, respectively, were given intravenous Evans blue dye as an indicator of blood-brain barrier breakdown. This was followed by the application of modified Zenker's solution to the dura in a manner identical to the clinical practice. When the animals were killed 1 or 2 hours later, the cortex beneath the dura painted with modified Zenker's solution was stained massively. The thickness of human dura was measured; it varied from 0.22 to 0.28 mm in infants of 3 months or less, 0.27 to 0.42mm in infants 4 months to 12 months of age, and 0.32 to 0.45 mm in children to 1 to 18 years of age. Modified Zenker's solution applied to fresh dura for 3 minutes at autopsy gave visual evidence 1 hour later of penetration to the cortex beneath. In operative procedures for craniosynostosis, 69 patients were treated with modified Zenker's solution; of these, 7 developed seizures in the immediate postoperative period. No seizures occurred among the 39 patients on whom modified Zenker's solution was not used. It is concluded that modified Zenker's solution applied to the dura can damage the cortex beneath.

Acetates↗
PubMed1981

Extraneural metastatic medulloblastoma during childhood.

From 1960 to 1977, 59 patients with histologically confirmed medulloblastoma were initially treated at Childrens Hospital of Los Angeles. Of this group, 49 have died and, of these, 34 were autopsied. Among the autopsied cases, 2 infants had neck masses that proved to be medulloblastoma that had spread from the cerebellar vermis before any surgical intervention. Four additional patients who had undergone a posterior fossa craniectomy without either the pre- or postoperative placement of a cerebrospinal fluid-diverting shunt were found to have extraneural metastatic medulloblastoma at autopsy. The extraneural metastatic medulloblastoma rate in the autopsied cases was 17.6% (6 of 34). Our series shows that the incidence of the extraneural spread of medulloblastoma is associated with being young, being male, and having diffuse tumor involvement of the subarachnoid space.

Age Factors↗
PubMed1981

Intracranial pressure monitoring in severe pediatric near-drowning.

Between April 1979 and April 1981, 20 near-drowned children admitted to Childrens Hospital of Los Angeles with a Glasgow coma score of 3 underwent intracranial pressure (ICP) monitoring and brain resuscitative therapy. By the 3rd hospital day, 14 patients had developed ICP elevation above 20 torr, and 11 of these had sustained intracranial hypertension above 30 torr. Ten of these children died, and 4 remain in a persistent vegetative state. Of 6 patients whose ICP never exceeded 20 torr, 3 recovered completely, 1 died, and 2 remain without any cognitive function. The salvage rate for patients with normal ICP after near-drowning accidents is significantly better than that for patients in whom the ICP is elevated (P = 0.017). Intracranial hypertension is associated with a uniformly bad outcome and is frequent in patients who die or suffer permanent, severe central nervous system damage after near-drowning.

Child↗
PubMed1980

Medulloblastoma presenting as neck tumors in 2 infants.

Extension of neuroepithelial neoplasms outside the neuraxis, though uncommon, is well known and usually follows surgical intervention. More unusual is the brain tumor that appears beyond the bounds of the central nervous system prior to operative manipulation. Two infants presented with soft tissue masses in the neck that proved to be medulloblastomas. Autopsy examination in both infants showed primary medulloblastoma of the cerebellar vermis with extensive spread through the subarachnoid spaces. The neck masses may have been direct extensions from the central nervous system tumors, though this was not proved in either case.

Cerebellar Neoplasms↗