Biomedical subjects
Publications and source records attributed to D Brockmeyer.
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The diagnosis and management of occipital-atlantal and atlantoaxial instability in Down syndrome patients is a challenging problem in pediatric spine surgery. To date, no systematic review of this topic has been presented on this confusing and sometimes contentious issue. This topic review will focus on the biomechanical and radiographic foundations for which treatment recommendations in Down syndrome patients are made. In addition, otolaryngologic and anesthetic considerations in Down syndrome are also discussed, as well as advances in surgery that have made the operative fusion of these patients easier and safer.
Endoscopic third ventriculostomy (ETV) has gained widespread acceptance as an effective way to manage hydrocephalus in selected patients. To determine which patient groups have the highest chance of successful ETV, a retrospective case review was performed. From June 1992 to December 1996, 97 patients underwent a total of 98 ETVs at our institution. There were 59 males and 38 females with a mean age of 8.1 years (range 1 day to 29.5 years). Twenty-six of 98 procedures (26%) were abandoned due to either unfavorable anatomy, inability to perform a cisternostomy, or hemorrhage. Follow-up data was available in 92 patients for a mean of 24.2 months. The rate of successful ETV in 71 patients, with either complete shunt avoidance or removal, varied widely by diagnosis and patient age. The highest success rates were achieved in patients with aqueductal stenosis, tectal plate tumor, myelomeningocele and posterior fossa tumor. Complications included one transient herniation syndrome, one basilar artery perforation, 2 cases of ventriculitis, one transient decrease in level of consciousness, and one transient hemiparesis. We feel these results support the continued use of ETV in only carefully selected patients with hydrocephalus.
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We describe 3 cases of Ochrobactrum anthropi meningitis following the implantation of pericardial allograft tissue to cover dural defects following craniotomy. Following an extensive epidemiologic investigation, the tissue allograft was found to have been contaminated with this unusual organism during the harvesting and processing of the tissue in the tissue bank. This organism was only susceptible to imipenem, tetracycline, gentamicin, and ciprofloxacin. The clinical presentation of these patients was subacute. Two of the patients developed osteomyelitis of the bone flap; while another developed a relapse of infection along a former ventriculoperitoneal shunt track 6 months after the initial infection. Appropriate clinical outcome was only observed after removal of tissue allograft implants, debridement of devitalized tissue and bone, removal of shunt devices, and prolonged courses of antibiotics. No deaths were observed.
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From July 1986 to August 1993 we performed 24 pediatric cervical spine screw fixation procedures on 23 patients 16 years of age or less. The types of cervical instrumentation procedures performed were as follows: anterior cervical plates 12, posterior C1-2 screw fixations 8, posterior lateral mass plates 2, odontoid screw fixations 2. The mean age of all patients was 14.2 years (range 6-16). Indications for operation included traumatic instability in 20 cases, congenital instability in 1 case, 2 cases of postoperative swan neck deformity, and one reoperation for early graft and hardware failure. Six of the 23 patients had persistent instability following previous failed fusions (3 with 1 prior surgery, 2 with 2 prior surgeries, and 1 with 3 prior surgeries). Eight patients had improvement of their neurological status following operation and 15 remained at their preoperative level of neurological function. No patient was worse neurologically after their procedure. There were no long-term instrumentation, graft or fusion failures. Two complications occurred. One was the aforementioned graft and hardware failure requiring reoperation, the other was a superficial wound infection treated successfully with antibiotics. We feel that cervical spine fixation techniques have increased our ability to stabilize the pediatric cervical spine and have proven to be safe and effective.
The human brain tumor, astrocytoma, typically progresses through three histopathologically defined stages with the passage of time: one premalignant stage, low-grade astrocytoma; and two malignant stages, anaplastic astrocytoma and glioblastoma multiforme. We correlated the results of a sequence analysis of the tumor suppressor gene, p53, and a restriction fragment length polymorphism analysis of chromosomes 17 and 10 in 45 patients with cerebral astrocytomas at different stages. To detect p53 mutations in tumor DNA, we analyzed polymerase chain reaction products corresponding to every p53-coding exon for single-strand conformation polymorphisms and confirmed the mutations by sequencing. Loss of heterozygosity (LOH) was determined by Southern transfer analysis of somatic and tumor DNA from these same patients using polymorphic markers for various loci on chromosomes 10 and 17. p53 mutations were found in 7 of 25 glioblastomas (28%), in 5 of 14 anaplastic astrocytomas (36%) but in 0 of 6 low-grade astrocytomas. p53 mutations were found in 62% of patients with LOH on chromosome 17p. These results indicated that p53 inactivation is a common genetic event in astrocytoma progression that may signal the transition from benign to malignant tumor stages. LOH on chromosome 10 was found in 61% of glioblastomas, in 23% of anaplastic astrocytomas, but in 0% of low-grade astrocytomas. LOH on chromosome 10 and p53 mutation were found together only in patients with glioblastoma multiforme (22%), suggesting that these genetic changes may accumulate during astrocytoma progression.