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Biomedical subjects

R M Scott

Publications and source records attributed to R M Scott.

At least 91 records · Page 5Linked to original sources
PubMed1994

Doppler sensor placement during neurosurgical procedures for children in the prone position.

Precordial ultrasonic Doppler devices are effective monitors for detecting venous air emboli (VAE). However, placing an ultrasonic probe on the anterior part of the chest of a prone patient can lead to dislodgment or pressure sores and makes the probe inaccessible to the anesthesiologist. The purpose of this study was to compare placement of a Doppler probe on the patient's back with the traditional precordial site for the ability to detect VAE. We enrolled infants and children undergoing neurosurgical procedures in the prone position in the study. After establishment of general anesthesia and endotracheal intubation, we applied an ultrasonic Doppler probe to the right sternal border of the patient's chest. Anterior insonation was performed with the patient in the supine position. Saline was rapidly injected to verify the efficacy of the monitor (injection test). The patient was turned to the prone position and we placed the Doppler probe between the right scapula and spine. Posterior insonation with saline injection was performed with the patient in the prone position. We obtained positive tests in all patients from the anterior site. Positive tests were obtained from the posterior site in 23 of 24 (96%) children < 10 kilograms (group I), 28 of 39 (72%) children between 10 and 20 kg (group II), and 6 of 22 (27%) children > 20 kilograms (group III). This study demonstrates that a posterior Doppler probe can be effective for monitoring infants at risk of VAE. However, this method is not reliable in children weighting > 10 kg.

Back↗
PubMed1994

Seizures in children with supratentorial astroglial neoplasms.

We reviewed the records of 98 consecutive patients, 18 years of age or younger, with pathologically confirmed supratentorial astroglial neoplasms at the Children's Hospital, Boston, to evaluate the importance of seizures in their presentation and natural history. Tumors were diagnosed using the WHO criteria as pilocytic astrocytomas, astrocytomas, anaplastic astrocytomas, glioblastomas, giant cell glioblastomas, oligoastrocytomas and gangliogliomas. Our results were as follows. (1) Fifty percent of children had seizures as part of their presentation and 30% had seizures as their only presenting phenomenon. (2) The seizures varied in nature, but complex (55%) or simple (28%) partial seizures were by far the most common types, occurring in 77% of cases. (3) Preoperative electroencephalography (EEG) accurately lateralized to the tumor side in 88% of the cases and localized to the correct lobe in 56%. (4) Tumors involving cerebral cortex significantly correlated with seizures at presentation as compared to noncortical locations; 59% of patients with cortical tumors presented with seizures, and only 15% of patients with noncortical tumors experienced seizures. Lesions in the temporal and frontal lobes had the highest incidence of seizures. (5) Patients with gangliogliomas and oligoastrocytomas had the highest incidence of seizures, 88 and 86%, respectively, whereas patients with anaplastic astrocytoma had the lowest incidence, 21%. (6) Histopathologic calcification was associated with seizures at presentation approaching significance (p = 0.06). (7) Seizures at presentation were significantly associated with good prognosis (p = 0.02).

Adolescent↗
PubMed1994

Surgery, radiation, and combination therapy in the treatment of childhood craniopharyngioma--a 20-year experience.

The records of 61 children treated for primary craniopharyngioma at the Children's Hospital in Boston and The Joint Center for Radiation Therapy from 1970 to 1990 were reviewed to determine if any information could be obtained regarding the efficacy of surgery versus radiotherapy or a combination of these modalities for this tumor. A select group of 9 children treated without biopsy by radiation therapy alone were all alive without disease progression at follow-up. Although 9 of the 15 children who underwent surgery alone had tumor recurrence, 7 of the 37 children treated with radiotherapy following surgery have also recurred. Treatment morbidity occurred in all groups, but the 10-year actuarial survival for all patients was 91%. Early postoperative imaging and pre- and posttreatment endocrine and neuropsychologic evaluations need to be carried out in all prospective studies of the treatment of craniopharyngioma in children.

Adolescent↗
PubMed1994

Advances in radiation therapy for craniopharyngiomas.

The overall survival for patients with craniopharyngioma is excellent. However, conventional treatments that include aggressive surgery and standard irradiation have been associated with significant morbidity. Focal radiation treatment with stereotactic radiosurgery has a role in selected cases, but may also be damaging to sensitive normal tissues such as the optic chiasm. Stereotactic radiotherapy (SRT) is a technique that allows for conventionally fractionated radiation under stereotactic guidance. Thus, highly focal and precise radiotherapy is now coupled with fractionation, enabling the treatment of selected tumors with a potentially improved therapeutic index. Dose optimization with SRT for focally discrete tumors should result in equivalent local control and survival compared to patients treated with conventional irradiation. We anticipate a significant decrease in late effects, especially neuropsychological and neuroendocrine sequelae.

Child↗
PubMed1993

20-year experience in childhood craniopharyngioma.

PURPOSE: The management of craniopharyngioma is controversial, and surgery alone is frequently advocated. The purpose of this study was to assess the long-term impact of various treatments in childhood craniopharyngioma. METHODS AND MATERIALS: Sixty-one children < or = 21 years of age at diagnosis were treated for craniopharyngioma at Children's Hospital and the Joint Center for Radiation Therapy in Boston from 1970 to 1990. The median age was 7.5 years (range 10 months-21 years). There were 33 females and 28 males. The median follow-up was 10 years (range 2-20.5 years). Neuroimaging was available for detailed review in 53. Nine children were treated with radiotherapy alone, 15 were treated with surgery alone, and 37 were treated with both surgery and radiotherapy. All patients in the radiotherapy and surgery plus radiotherapy groups were treated with megavoltage radiation with a median dose of 5464 cGy. RESULTS: All nine of the children treated with radiation therapy alone are alive; none have recurred. Nine of the 15 children treated with surgery alone have recurred (p = 0.007 Fisher exact test). Two are alive with disease, and seven are alive without disease after treatment at relapse with radiation therapy, surgery, or both. Seven of the 37 patients treated with surgery plus radiotherapy have recurred. Three of the seven patients are dead of disease, three patients are alive with disease, and one patient is alive without disease after further treatment. The 10-year actuarial overall survival was 91% for all patients. The 10-year actuarial freedom from progression for the surgery group was 31% compared with 100% for patients treated with radiation therapy only (log rank p = 0.01), and 86% for patients treated with surgery plus radiotherapy at diagnosis (p = 0.001). There were two treatment related deaths, both in the surgery plus radiotherapy group. A higher incidence of visual loss and diabetes insipidus was associated with the use of aggressive surgery. The size of the tumor at presentation correlated with an increased risk of recurrence; 5 of 6 patients with tumors > or = 5 cm experienced recurrences while only 6 of 30 recurred when the tumor was < 5 cm. CONCLUSIONS: Overall survival in childhood craniopharyngioma is excellent. However, patients treated with surgery alone have a significantly worse freedom from progression when compared to patients treated with surgery and radiation therapy or radiation therapy alone.

Actuarial Analysis↗
PubMed1993

The neurosurgical implications of continuous neurourological surveillance of children with myelodysplasia.

Between 1979 and 1990, 148 newborns with myelodysplasia were followed with serial urodynamic studies and neurological assessment. Of the patients 59 (40%) exhibited changes in neurological status by age 5 years, of whom 28 (19%) showed signs of deterioration. Most changes occurred before age 2 years. A total of 22 children underwent repeat neurosurgical exploration because of a change in urethral sphincter innervation (17), deterioration of function of the lower extremities (3), or changes on computerized tomography or magnetic resonance imaging (2). Postoperative urodynamic evaluation demonstrated improvement in 11 children, stabilization in 9 and further deterioration in 2. The earlier that a change was detected and secondary surgery was performed, the better the outcome. These findings indicate that the neurological lesion in myelodysplasia is a dynamic disease process requiring continuous neurological, orthopedic and urodynamic surveillance. Early identification and prompt neurosurgical reexploration seem to arrest and even reverse the neurological deterioration that takes place in a substantial number of these children.

Child, Preschool↗
PubMed1993

Epidural hematomas in children.

STUDY OBJECTIVE: To describe the presentation, management, and outcome of children with traumatic epidural hematoma. DESIGN: Retrospective chart review. TYPE OF PARTICIPANTS: Fifty-three children diagnosed with traumatic epidural hematoma on computed tomography scan who were treated at Children's Hospital in Boston between 1980 and 1990. MAIN RESULTS: Twenty-four of 53 children developed an epidural hematoma after a fall of less than 5 ft. At the time of diagnosis, 51 of 53 children had one or more symptoms of vomiting, headache, or lethargy. Twenty-six patients were alert, 21 were responsive to verbal or painful stimuli, and five were unresponsive or posturing. Twenty-one (40%) had acute neurologic deterioration before surgery; however, 20 (38%) were alert with normal vital signs and neurologic examinations at diagnosis. All patients survived, and at the time of discharge 45 had normal examinations and eight had neurologic abnormalities; at follow-up only four of these eight had persistent (although mild) abnormalities. CONCLUSIONS: Although often dramatic in presentation, epidural hematoma may occur after relatively minor head trauma and in alert children with nonfocal neurologic examinations. In our study, incidence of neurologic sequelae increased if abnormal neurologic examination or depressed mental status was present at diagnosis. The outcome of children in this study is improved from that of previous studies, perhaps due to increased use of computed tomography and higher incidence of low- or moderate-impact trauma in this series.

Adolescent↗
PubMed1993

Tethered spinal cord in patients with anorectal and urogenital malformations.

We reviewed 26 patients with anorectal or urogenital malformations managed by the neurosurgical service at The Children's Hospital for tethered spinal cord as diagnosed by spinal MRI. There were 13 patients with cloacal exstrophy, 5 with the Vater association, 3 with imperforate anus, and 5 with other complex anomalies. Tethering spinal cord lesions included myelocystocele, lipomyelomeningocele, and filum lipoma. We review the clinical course, management, correlation of MRI and intraoperative findings, and outcome of the patients, as well as the embryology which underlies the association of these malformations.

Adolescent↗
PubMed1993

Prognostic factors in medulloblastoma, including DNA ploidy.

PURPOSE: DNA ploidy status, completeness of surgical resection, use of chemotherapy, adequacy of radiation therapy, metastatic stage, sex, and age at diagnosis were evaluated as predictors of relapse in 58 patients with cerebellar medulloblastoma. METHODS: Flow cytometry (FCM) and/or image analysis (IA) were used to characterize tumor DNA ploidy. Twelve tumors (21%) were found to be aneuploid, 11 (19%) tetraploid, and 35 (60%) diploid. RESULTS: The most significant predictors of relapse in univariate analyses were the adequacy of radiation (> or = 50 Gy) (P = .02), metastatic staging (P = .05), completeness of resection (P = .085), and DNA ploidy status (diploid/tetraploid v aneuploid; P = .11). When the 52 patients who received > or = 50 Gy were included in a multivariate Cox model analysis, those with diploid/tetraploid tumors had fewer recurrences than those with aneuploid tumors (relative risk, 0.33; 95% confidence interval, 0.12 to 0.89; P = .03). Patients with complete resections (P = .07), or with stage M0 disease (P = .06) had fewer recurrences than other patients, but these factors were not independent predictors of outcome. DNA ploidy status was correlated with age; 10 of the 12 aneuploid tumors were found in children ages 3 to 10 years. Age, sex, and the use of chemotherapy were not prognostically significant in these analyses. CONCLUSION: The adequacy of radiation dose and DNA ploidy were the most important prognostic factors in this series. Contrary to previous reports, when corrected for adequacy of treatment, DNA aneuploidy was associated with a poor outcome. By multivariate analyses, DNA ploidy was an independent variable, even when controlling for extent of surgical resection and metastatic stage.

Aneuploidy↗
PubMed1993

Thallium-201 versus technetium-99m-MIBI SPECT in evaluation of childhood brain tumors: a within-subject comparison.

We previously found that 201TI SPECT is a highly specific agent for detection of metabolic activity of childhood brain tumors. To compare the relative diagnostic accuracy of 201TI and a technetium-based tumor-avid agent, we have obtained SPECT in 19 children using 201TI (37-111 MBq) followed immediately by 99mTc-methoxyisobutylisonitrile (MIBI) (370-740 MBq) intravenously. Moderate to intense focal uptake of both tracers characterized true positive cases (n = 6). Lesion boundaries were better defined by MIBI. Uptake of MIBI by choroid plexus occurred despite pretreatment with potassium perchlorate (6 mg/kg) and complicated interpretation of deep/paraventricular lesions. Preliminary assessment indicated sensitivity approximately 67% (TI and MIBI); specificity approximately 91% (TI); approximately 100% (MIBI). Two tumors (medulloblastoma, dysgerminoma) were TI/MIBI nonavid. Semi-quantitative assessment of tracer uptake was made using a ratio of radioactivity in tumor-containing areas compared to uninvolved brain. Ratio values were (mean +/- s.d.) 7.88 +/- 7.70 (TI) and 27.1 +/- 36.41 (MIBI). The spectrum of tumor avidity is similar for TI and MIBI. Clearer identification of boundaries by MIBI may be an advantage in applications, e.g., radiotherapy port planning.

Brain Neoplasms↗
PubMed1993

Chiari malformations, syringomyelia, and intramedullary spinal cord tumors.

Optimal management of congenital and acquired spinal cord lesions, such as Chiari malformations, syringomyelia, and intramedullary spinal cord tumors, depends on an understanding of the pathogenesis and natural history of these lesions. Magnetic resonance imaging and detailed physiologic investigations are shedding new light on these difficult-to-diagnose entities, and new surgical techniques are aiding in their management.

Arnold-Chiari Malformation↗
PubMed1992

Bladder functional changes resulting from lipomyelomeningocele repair.

From 1986 to 1991, 12 boys and 23 girls underwent surgery for lipomyelomeningocele removal. Of these patients 29 were 15 months old or younger (average age 3 months), while 6 were 4.5 to 19 years old (average age 10 years). Preoperative and postoperative urodynamic studies, including external urethral sphincter electromyography, were done on everyone. All 29 infants had a cutaneous lesion overlying the lower back and 14 had an abnormal neurological examination. Preoperative urodynamic studies were abnormal in 11 patients, consisting of an upper motor neuron lesion in 6, and a mixed upper and lower motor neuron lesion in 5. Postoperatively, 10 of 14 children with an abnormal neurological examination improved, while 9 of 11 with abnormal lower urinary tract function normalized. In 1 of 18 children (6%) with normal preoperative urodynamic studies detrusor-sphincter dyssynergia developed postoperatively. In all 6 older children urinary incontinence developed, and this led to the diagnosis. Everyone had an abnormal neurological examination and abnormal preoperative urodynamic studies. One child had a lower motor neuron lesion, and 5 had a mixed upper and lower motor neuron lesion. Postoperatively, the neurological examination improved in only 1 patient (16%), and the urological symptoms and urodynamic findings improved in another child. Lipomyelomeningocele has a progressive effect on lower spinal cord function because infants tend to present with fewer urinary manifestations and physical findings than older children. Individuals who escape early detection tend to have a more subtle cutaneous abnormality. As a result, older children are more likely to present with urological and neurological complaints. Surgical correction in infancy provides a degree of reversibility not seen in older children. It is imperative that early identification, evaluation and treatment be undertaken to prevent this progression and permanency of neurological changes and urinary dysfunction.

Adolescent↗
PubMed1992

Fibrous dust release from asbestos substitutes in friction products.

A small-scale study was carried out on friction and reinforcing materials containing Kevlar and glass fibres. Kevlar, an aramid fibre, and synthetic silicate fibres are being increasingly used in brake pads and shoes for cars and trucks. The fibre levels given out under abrasion in the laboratory were low. As a comparison, a brake pad containing asbestos was also tested and gave high levels of airborne fibres.

Asbestos↗
PubMed1992

Cavernous angiomas of the central nervous system in children.

A surgical series of 19 patients under the age of 18 years with pathologically verified cavernous angioma is presented. Most lesions were located in the cerebral hemispheres, but four were in the pons or midbrain, two in the diencephalon, and one in the spinal cord. Fourteen patients presented with an acute or progressing neurological deficit, three with seizures, one infant with irritability, and one with headache alone. Five patients had family histories of vascular malformations of the central nervous system, and five had multiple lesions. Surgery for small or deep lesions was aided considerably by intraoperative ultrasonographic or stereotactic localization techniques. Pathological examination of the resected malformations revealed a complex histology containing not only typical closely approximated cavernous vessels, but also areas of marked proliferation of granulation tissue and partially re-endothelialized hemorrhage, suggesting a mechanism for the apparent growth of certain cavernous angiomas. The postoperative results were good, with only one patient suffering a permanent worsening of neurological status after surgery. Incomplete resection was initially carried out in five patients, two of whom rebled within 1 year after operation. Long-term follow-up findings in these patients have emphasized the unusual history of certain of these malformations.

Adolescent↗