Reduction of total knee replacement wear with vitamin E blended highly cross-linked ultra-high molecular weight polyethylene.

Ultra-high molecular weight polyethylene (UHMWPE) is a common bearing component in total knee replacement (TKR) implants, and its susceptibility to wear continues to be the long-term limiting factor in the life of these implants. This study hypothesized that in TKR systems, a highly cross-linked (HXL) UHMWPE blended with vitamin E will result in reduced wear as compared to a direct compression-moulded (DCM) UHMWPE. A wear simulation study was conducted using an asymmetric lateral pivoting '3D Knee' design to compare the two inserts. The highly cross-linked UHMWPE was aged prior to the testing and force-controlled wear testing was carried out for 5 million cycles using a load-controlled ISO-14243 standard at a frequency of 1 Hz on both groups. Gravimetric measurements of DCM UHMWPE (4.4 +/- 3.0 mg/million cycles) and HXL UHMWPE with vitamin E (1.9 +/- 1.9 mg/million cycles) showed significant statistical differences (p < 0.01) between the wear rates. Wear modes and surface roughness for both groups revealed no significant dissimilarities.

Radioimmunodetection of human glioma xenografts by monoclonal antibody to epidermal growth factor receptor.

Murine IgG2a monoclonal antibody (MAb) 425 specifically detects epidermal growth factor receptor, which is expressed on human gliomas and tumors of other tissue origin but rarely on normal brain tissues, and not at all on bone marrow and peripheral blood cells. 131I-labeled F(ab')2 fragments of this MAb injected into nude mice grafted with U-87 MG glioma cells preferentially localized in tumor tissue compared to normal mouse tissues, as determined by differential tissue counting of radioactivity. The mean tumor-to-tissue ratios of radioactivity ranged between 8.2 (blood) and 55.8 (muscle) at 2 days after the injection of 15 muCi of 131I-425 F(ab')2/mouse. Radiolabeled fragments of an anti-hepatitis virus IgG2a MAb did not localize in tumors. The localization index derived from the ratios of specific antibody to indifferent antibody in tumor tissue relative to blood was 9.94 at 2 days following the MAb injection. The labeled MAb did not localize in a xenograft of colorectal cancer tumor, which does not express the epidermal growth factor receptor. Tumors could be located by whole-body gamma-scintigraphy without background subtraction following the injection of 100 muCi of radiolabeled MAb 425 F(ab')2 fragments. The data suggest that MAb 425 is a likely candidate for clinical diagnostic and radioimmunotherapy trials.

Brainstem gliomas of childhood: magnetic resonance imaging.

We compared magnetic resonance imaging (MRI) and CT on 16 children with brainstem gliomas. MRI demonstrated masses of decreased signal intensity, which enlarged and distorted brainstems in all patients with active disease and showed brainstem abnormalities in 21 of 23 studies (91%). In one-half of the patients, MRI showed more extensive disease than did CT. Exophytic portions of tumors were shown well on MRI. MRI was more sensitive than CT in demonstrating disease relapse.

Results of a pilot study of hyperfractionated radiation therapy for children with brain stem gliomas.

The majority of children with brain stem gliomas develop progressive disease within 18 months of diagnosis and treatment. Radiotherapy (RT) is of transient benefit in most patients and higher total doses of RT have been related to improved survival. The amount of RT which can be given is limited by the tolerance of the surrounding brain. Hyperfractionated RT theoretically allows higher doses of RT to be tolerated by the brain. Sixteen children with brain stem gliomas were treated on a hyperfractionated RT schedule, receiving 120 cGy of RT twice daily, to a total dose of 6480 cGy. All patients tolerated treatment well. Eleven of 15 (73%) evaluable patients had a response to treatment and two (13%) others had stable disease. One patient developed progressive disease during treatment. All patients were tapered off steroids by the completion of treatment. Thirteen of 16 (81%) patients developed progressive disease at a median of 7 months after diagnosis and three remain in remission 8, 12, and 15 months following diagnosis. These results were similar to those of historical controls. Two patients were surgically explored at time of relapse and 5 have had an autopsy. No acute or subacute neurologic toxicity was seen; but long-term detrimental effects on brain could not be assessed. The implications of this study are that escalations of the dose of hyperfractionated RT can be entertained for children with brain stem gliomas.

Management of the newborn with myelomeningocele: time for a decision-making process.

The relationship between time of surgical intervention and eventual outcome was examined in 110 newborns with myelomeningocele. Numerous earlier reports have cited a significant increase in mortality and morbidity associated with delay of surgery beyond 48 hours. Within the study population of infants, 52 infants (47%) had "early" surgery within the first 48 hours of life, 32 infants (29%) had "delayed" surgery between 3 and 7 days of age, 12 infants (11%) had "late" surgery between 1 week and 10 months of age, and 14 infants (13%) never had surgery by parental decision. Survival rates were similar between those with early, delayed, or late surgery as 92%, 94%, and 100%, respectively, were alive at age 10 months. Also, no significant association existed between time of surgery and development of ventriculitis, developmental delay, or worsening of paralysis. From these observations, it is concluded that there is no urgency in surgical intervention for the initial management of newborns with myelomeningocele. Rather, there is time for comprehensive discussions, counseling, and emotional support for those parents in need of a decision-making process before establishing consent for or against surgical management of their newborn.

Magnetic resonance imaging of lesions of the posterior fossa and upper cervical cord in childhood.

Magnetic resonance imaging (MRI) promises to be an effective, noninvasive means of visualizing intracranial pathology. It should be especially useful in the evaluation of posterior fossa and cervical spinal cord disease of childhood; computed tomographic (CT) evaluation is frequently suboptimal in this region. MRI results are reported for 46 consecutively seen children with posterior fossa and/or cervical spinal cord disease (28 had brain malignancies; seven had congenital anomalies; three had cerebrovascular accidents). MRI was performed primarily by the partial saturation on a .12 Tesla resistive proton unit. All patients underwent concurrent CT evaluation. MRI demonstrated abnormalities in 96% of scans in patients with structural CNS disease (48 of 50). CNS malignancies were visualized in 100% (28 of 28) of children studied. MRI was especially useful in demonstrating the full extent of infiltrating gliomas and the anatomic location of other mass lesions. MRI frequently demonstrated disease to be more extensive than seen on CT. MRI was more sensitive than CT in documenting response to treatment and disease relapse in patients with infiltrating tumors. Cystic regions within tumors were poorly seen on MRI. Congenital anomalies were demonstrated in all patients evaluated and were better delineated using MRI than CT. MRI is sensitive in the evaluation of posterior fossa and cervical spinal cord disease of childhood and it has obvious advantages over CT; however, its specificity in such evaluations has yet to be proven.

Magnetic resonance imaging of spinal cord disease of childhood.

Correct diagnosis of spinal cord disease in childhood is often delayed, resulting in irreversible neurologic deficits. A major reason for this delay is the lack of a reliable means to noninvasively visualize the spinal cord. Magnetic resonance imaging (MRI) should be useful in the evaluation of diseases of the spinal cord. A 1.5 Tesla MRI unit with a surface coil was used to study 41 children, including eight patients with intrinsic spinal cord lesions, eight patients with masses compressing the cord, 12 patients with congenital anomalies of the cord or surrounding bony structures, three patients with syrinxes, and three patients with vertebral body abnormalities. Intrinsic lesions of the cord were well seen in all cases as intrinsic irregularly widened, abnormally intense cord regions. MRI was helpful in following the course of disease in patients with primary spinal cord tumors. Areas of tumor were separable from syrinx cavities. Extrinsic lesions compressing the cord and vertebral body disease were also well visualized. Congenital anomalies of the spinal cord, including tethering and lipomatous tissue, were better seen on MRI than by any other radiographic technique. MRI is an excellent noninvasive "screening" technique for children with suspected spinal cord disease and may be the only study needed in many patients with congenital spinal cord anomalies. It is also an excellent means to diagnose and follow patients with other forms of intra- and extraspinal pathology.

Pineal region tumors of childhood.

The incidence, response to treatment, and outcome of children with pineal region neoplasms is poorly characterized. Since 1975, in one institution, 25 consecutive patients with pineal tumors have undergone biopsy prior to further treatment. This constituted 11% (25/234) of all brain neoplasms seen over this time period. Specific tumors diagnosed included pineal parenchymal tumors ( pineoblastomas , pineocytomas ) in eight patients (32%); germ cell tumors (embryonal cell carcinomas, teratomas, germinomas) in eight patients (32%); glial tumors (astrocytoma, ganglioglioma ) in eight patients (32%); and ganglioneuroblastoma in one patient (4%). Clinical parameters, computed tomographic findings and CSF markers (alphafetoprotein and human chorionic gonadotropin) were unreliable in discriminating between specific tumor types. Response to treatment and patterns of disease relapse were dependent on the type of tumor present. Five of eight children with pineal parenchymal tumors had disease recurrence, and in all leptomeningeal dissemination occurred prior to or concurrent with local relapse. Three of eight children with germ cell tumors and two of eight patients with glial tumors suffered a relapse; in all five children recurrence was initially local. Findings suggest that pineal region neoplasms are not infrequent in childhood; that these tumors vary greatly in histologic type; that contrary to other reports germinomas do not constitute the majority of pineal tumors; and that histologic confirmation is necessary prior to treatment for appropriate management.

Global rostral midbrain dysfunction secondary to shunt malfunction in hydrocephalus.

Two cases of congenital hydrocephalus with shunt malfunction are described. Both patients presented with clinical syndromes suggestive of global rostral mesencephalic dysfunction, including the sylvian aqueduct syndrome, a parkinsonian-like state, and quadriparesis. Each had computed tomographic findings that showed marked dilatation of the lateral and 3rd ventricles, and both improved with revision of their shunts. The anatomical substrates of the clinical findings are reviewed. A discussion of the probable mechanism proposes that dilatation of the 3rd ventricle and rostral aqueduct sufficiently explains the entire syndrome. (Neurosurgery, 7: 322-325, 1980).

Hydranencephaly versus maximal hydrocephalus: an important clinical distinction.

To define better the syndromes of hydranencephaly and maximal hydrocephalus, we followed 10 neonates demonstrating (by computerized tomography) virtual absence of the cerebral substance with serial computerized tomographic (CT) scans, electroencephalograms (EEGs), and developmental evaluations. The follow-up period ranged from 4 to 23 months. Two well-defined syndromes emerged. Five patients showed absence of cortical activity on EEG and a CT picture of minimal occipital brain parenchyma connected by a thin bridge of tissue to intact basal ganglia. These patients were shunted and showed no improvement with time, either neurologically or radiologically. Five patients showed minimal frontal cerebral mantle on CT and the presence of electrical activity on EEG. These patients required bilateral shunts to control head size and showed remarkable progress with time. Serial CT scans demonstrated the appearance of considerable brain substance, and neurological development was either normal or slightly delayed. We believe that the former pattern of only minimal occipital brain and absent EEG activity defines true hydranencephaly, whereas the presence of small amounts of frontal brain tissue associated with EEG activity seems to represent maximal hydrocephalus. The differences in CT pattern, EEG, and clinical progress all suggest a different pathophysiology for these two conditions. (Neurosurgery, 6: 35--38, 1980).

Single stage composite resection and reconstruction of malignant anterior skull base tumors.

Operative morbidity, including osteomyelitis and meningeal and cerebral sepsis, remains high among patients undergoing the composite (bony and overlying soft tissue) resection of malignant skull base tumors. This is in part because of the poor wound healing afforded by free skin grafts and the poorly vascularized pericranial flaps routinely used to resurface the operative defect. In an effort to reduce the operative morbidity, single stage resection and reconstruction with distant vascularized flap tissue was performed in five consecutive patients who presented with malignant skull base tumors. We think that immediate flap reconstruction will allow skull base lesions previously considered unresectable or associated with a prohibitive complication rate to be safely resected. Case presentations illustrate operative techniques. The potential disadvantage of masking a tumor recurrence with immediate flap coverage is discussed.

Effects of hydrocephalus and increased intracranial pressure on auditory and somatosensory evoked responses.

Recent studies in human and animal subjects have suggested a relationship between intracranial pressure (ICP) and ventricular dilatation and multimodality evoked responses which, if substantiated, would be of value to clinical practice as a noninvasive way of assessing the need for shunting in selected patients in whom computed tomography (CT) is not definitive. In an attempt to better define these changes, auditory evoked response (BAER) and somatosensory evoked response (SER) were performed on 16 cats as a base line, after which they were made hydrocephalic by the cisternal injection of kaolin. Nine cats survived, and CT or magnetic resonance scans were performed on them 4 to 6 weeks later. In those animals in which ventricular dilatation was noted, repeat evoked responses were recorded. In the 6 hydrocephalic cats, the ventricle was punctured to measure ICP, which in all cases was less then 5 mm Hg. The lumbar spinal dural sac was then ligated, which resulted in periodic plateau waves up to 75 to 100 mm Hg after 4 to 6 hours, lasting up to 10 minutes. In neither group of cats was any change in either BAER or SER observed until preterminally, when ICP was in the range of 75 to 100 mm HG and cerebral perfusion pressure was compromised. This suggests that the BAER and SER are not sensitive to either ventricular dilatation or intracranial hypertension.

Cerebral gangliogliomas during childhood.

We have reviewed our experience with gangliogliomas treated in the post-computed tomography (CT) era at the Children's Hospital of Philadelphia. Of 234 newly histologically verified neoplasms seen at our institution since 1975, 10 (4.3%) were gangliogliomas of the cerebral hemispheres. The presenting complaint was seizures in 9 of 10 patients, and in 8 the seizures were poorly controlled despite increasing doses of anticonvulsant medication. At the time of diagnosis, only 2 patients had a focal neurological deficit and none had signs or symptoms of increased intracranial pressure. Learning disability and behavioral disturbances were common in this group of children. The CT appearance of these lesions was characteristic: most appeared as a cerebrospinal fluid density area that was located peripherally and often indented the skull. There was little contrast enhancement, and a few were diagnosed initially as arachnoid or porencephalic cysts. Despite the CT appearance, all but 2 of the lesions were found to be solid at operation. In one patient, the lesion appeared as an enhancing lesion of the thalamus, and this patient died. Operation resulted in symptomatic improvement. Eight of 9 children are alive, with a follow-up of 1 to 80 months (median, 19.5 months), and are free of progressive disease. Five are seizure-free while receiving anticonvulsant therapy and an additional 3 have improved seizure control as a result of operation. Two of the 3 children with intellectual difficulties preoperatively have shown improvement on testing after operation, probably the result of improved seizure control. One patient developed a disseminating malignancy and died. It is concluded that worsening seizures in the pediatric age group should warrant CT examination and that ganglioglioma should be included in the differential diagnosis of low density areas on CT.

Discrepancy between computed tomography and magnetic resonance imaging in a case of medulloblastoma.

In a 2-year-old girl with signs and symptoms of a posterior fossa tumor, the computed tomographic scan showed what appeared to be a brain stem glioma. However, magnetic resonance imaging (MRI) demonstrated the lesion to be extrinsic to the brain stem. Posterior fossa exploration disclosed a medulloblastoma filling the 4th ventricle. This discrepancy in imaging techniques points out the usefulness of MRI in the evaluation and treatment of posterior fossa lesions.

Improved relapse-free survival in medulloblastoma utilizing modern techniques.

Between 1969 and 1979, 22 patients with medulloblastoma were treated by the same surgical group and radiation therapy group. The patients were divided into two groups because of the clinical availability in December 1974 of the computed tomographic (CT) scanner and of the operating microscope used in the initial surgical procedure. There were 11 patients in each group. The percentage of patients with a relapse-free survival in the group treated between 1969 and 1974 (Group 1) was 38% at 4 years. The survival in the 11 patients treated between 1974 and 1979 (Group 2) was 84% at 4 years. This improvement is statistically significant (P less than or equal to 0.001). All patients received the same dose of radiation. Efforts to minimize the tumor burden by total surgical resection did not increase postoperative morbidity or mortality. These results are discussed, along with the relative impact of the CT scan, total resection at operation, and increased focus for radiation therapy on the improved outcome.

Localized primary intracranial Ewing's sarcoma of the orbital roof. Case report.

A rare case of a primary Ewing's sarcoma arising from the intracranial portion of the right orbital roof is presented. Clinical presentation was that of a rapidly growing tender exostosis, associated with headaches. History indicated that the tumor may have been present for more than 1 year. Skull x-rays showed marked diastasis of the coronal suture and a "mottled" appearance on the right frontal bone suggestive of a sarcoma. Bone scan further confirmed the presence of a malignant bone tumor. Computerized tomography scan showed the intracranial extension of the tumor and a follow-up scan allowed us to see the response of the tumor to therapy. Only two other cases with details as to intracranial localization were found in the literature.

The effects of cold-induced brain edema and white-matter ischemia on the somatosensory evoked response.

The electrophysiological effects of cold-lesion edema and white-matter ischemia were studied in cats by reference to the short-latency somatosensory evoked response. The primary cortical waves were found to be considerably delayed following a period of white-matter ischemia; hosever, cold-lesion edema appeared to have no significant effect on the evoked response. The authors conclude that vasogenic edema does not interfere with axonal functioning by an ischemic mechanism.

Bioenergetics of acute vasogenic edema.

The bioenergetic mechanisms of vasogenic edema were studied by measuring concentrations of adenosine triphosphate (ATP), phosphocreatine (CrP), and lactate in rapidly frozen edematous white matter in cats. When edema was produced using a cold lesion, it was found that both ATP and CrP were reduced to one-half of control values, and that lactate was elevated. When a correction was applied for dilution, however, it was found that high-energy phosphates were equal to control values, and that lactate was even more significantly elevated. This pattern contrasted with that seen in white-matter ischemia, in which CrP is depressed out of proportion to ATP. Finally, it was found that the white-matter lactate-concentration in the plasma infusion model of edema was increased. It is concluded that vasogenic edema induces an increase in lactate, but does not deplete high-energy phosphate compounds in affected white matter.

Vertebrobasilar spasm: a significant cause of neurological deficit in head injury.

Cerebral vasospasm in the anterior circulation has been recognized as a significant factor in the sequelae of head injury; however, vertebrobasilar spasm resulting from trauma has received much less attention. In the past year we have observed six patients where spasm in the major vessels of the posterior circulation was primarily or in part responsible for the neurological deficit. In such cases, the neurological examination may suggest a supratentorial mass with herniation and, in three of our cases, burr holes or carotid angiography were performed first. However, in every instance neurological signs present on admission indicated primary brain-stem dysfunction. In each of the six cases vertebral angiography demonstrated significant spasm in either the vertebral or basilar arteries. Intracranial pressure was monitored in each of the six patients and did not exceed 25 mm Hg in any. In cases of head injury where the neurological examination indicates brain-stem dysfunction inconsistent with or after a supratentorial mass has been excluded, vertebral angiography may aid in the diagnosis and subsequent management of such patients.