Biomedical subjects

D S Knierim

Publications and source records attributed to D S Knierim.

5 recordsLinked to original sources

PubMed2000

Predictive value of proton magnetic resonance spectroscopy in pediatric closed head injury.

We studied 26 infants (1-18 months old) and 27 children (18 months or older) with acute nonaccidental (n = 21) or other forms (n = 32) of traumatic brain injury using clinical rating scales, a 15-point MRI scoring system, and occipital gray matter short-echo proton MRS. We compared the differences between the acutely determined variables (metabolite ratios and the presence of lactate) and 6- to 12-month outcomes. The metabolite ratios were abnormal (lower NAA/Cre or NAA/Cho; higher Cho/Cre) in patients with a poor outcome. Lactate was evident in 91% of infants and 80% of children with poor outcomes; none of the patients with a good outcome had lactate. At best, the clinical variables alone predicted the outcome in 77% of infants and 86% of children, and lactate alone predicted the outcome in 96% of infants and 96% of children. No further improvement in outcome prediction was observed when the lactate variable was combined with MRI ratios or clinical variables. The findings of spectral sampling in areas of brain not directly injured reflected the effects of global metabolic changes. Proton MRS provides objective data early after traumatic brain injury that can improve the ability to predict long-term neurologic outcome.

Aspartic Acid↗

PubMed1990

Direct approach to arteriovenous malformations in functional areas of the cerebral hemisphere.

The natural history of patients with arteriovenous malformations (AVM's) suggests that serious morbidity associated with AVM's in functional areas is likely to be much greater than in silent areas. Various modes of treatment of AVM's in functional areas, including direct surgical intervention, embolization, and irradiation, have been considered to carry high risks. The authors advocate direct surgical intervention to these AVM's via a microsurgical technique based on knowledge of the hemodynamic anatomy of AVM's. The technique is designed to circumscribe the AVM without removing any surrounding cortical tissue or white matter and to preserve microcirculation in the functional area. Controlled hypotension (mean arterial blood pressure 40 to 60 mm Hg) is appropriate to enhance the safety of surgical procedures without causing metabolic and electrophysiological dysfunction. Another means to prevent neurological complications is multi-staged resection of larger AVM's, which permits obliteration compartment by compartment. This technique has the advantage of maintaining circulatory sufficiency in the functional area. There was no mortality among 56 patients who underwent the surgical procedure described. Of those, 55 patients resumed their preoperative occupation and one patient became self-sufficient.

Adolescent↗

PubMed1989

Pediatric choroid plexus neoplasms: MR, CT, and pathologic correlation.

Choroid plexus papillomas are rare, constituting approximately 0.5% of all intracranial neoplasms. Four benign choroid plexus papillomas and one choroid plexus carcinoma were retrospectively reviewed in patients aged 4-20 months who had been examined with magnetic resonance (MR) imaging with a field strength of 0.5 T or 1.0 T and with computed tomography (CT) before and after the administration of contrast material. In general, the tumors were of intermediate signal intensity on T1-weighted images and of either intermediate or increased signal intensity (T2 lengthening) with T2 weighting. All demonstrated variable areas of internal signal void interpreted as signifying regional blood flow, calcification, or old hemorrhage. CT findings included relatively uniform contrast enhancement. Microscopic pathologic changes of the benign lesions mimicked the appearance of normal choroid plexus and confirmed the highly vascular nature of these tumors. MR imaging, with its high-resolution multiplanar techniques, offers direct visualization of these lesions in relation to normal anatomy and better discrimination and confirmation of their intraventricular location, facilitating surgery and postoperative follow-up.

Carcinoma↗

PubMed1987

Lumbosacral intramedullary myolipoma. Case report.

Intradural myolipoma is an unusual tumor. A case is described in which extramedullary and intramedullary striated muscle fibers caused gross contraction of a lipomatous tumor as well as of the spinal cord during electrical stimulation.

Humans↗

PubMedDate not supplied

Choroid plexus tumors in infants.

Choroid plexus tumors continue to be a challenge in their diagnosis, treatment, and associated conditions that occur in perioperative management. Improved radiographic techniques have recently aided surgical planning, and recent developments in operating room technology are having an impact on the favorable outcome of these patients. Cerebrospinal fluid dynamics often add to the complexity of the perioperative management.

Carcinoma↗