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Biomedical subjects

H A Wilkinson

Publications and source records attributed to H A Wilkinson.

At least 19 recordsLinked to original sources
PubMed1992

Intrathecal Depo-Medrol: a literature review.

Intrathecal methylprednisolone acetate (IT-MPA) treatments have been reported to be beneficial and safe for the treatment of low back problems and especially "failed back" problems, which include adhesive arachnoiditis. Other reports, however, have stressed the potential dangers of this treatment and have advised against its use. Many of these papers implicate the propylene glycol included in the methyl-prednisolone as being potentially harmful. Since the literature is rather extensive and clearly conflicting, it is difficult for those who treat patients with "failed back" problems to ascertain the risk/benefit ratio of this form of treatment, so a literature review and analysis has been undertaken. Published literature clearly attests to the usefulness and general safety of IT-MPA when used within certain limits. Although several studies implicate IT-MPA as a potential cause of arachnoiditis or other neurologic injury, most of the evidence is circumstantial and most complications followed multiple, large-dose, or frequent injections.

Animals↗
PubMed1989

Erroneous measurement of intracranial pressure caused by simultaneous ventricular drainage: a hydrodynamic model study.

Intracranial pressure (ICP) is often measured from intraventricular catheters, a technique that allows therapeutic drainage of ventricular cerebrospinal fluid (CSF) as an aid in controlling ICP and circumventing obstruction. Drainage of CSF simultaneously with ongoing ICP measurement has been advocated as safe and efficient, and devices are commercially available to permit this practice; however, this concept has been seriously challenged, based on clinical observations. The inaccuracy induced by simultaneous CSF drainage and ICP monitoring is quantitated in this report in a mechanical brain model using a standard ventricular catheter. The following conclusions have been confirmed: 1) rapid CSF drainage induces a severe artifactual reduction in measured ICP, more extreme at higher pressures; 2) calibrated slower rates of CSF drainage produce a severe, although less immediate, reduction in measured ICP; 3) severe artifact appears even in the presence of continuous CSF outflow, so a system that measures ICP only in the presence of CSF flow does not prevent artifact; 4) with simultaneous CSF drainage, measured ICP is determined more by the outflow pressure setting than by actual brain pressure; 5) Since ICP elevation of 25 to 30 mm Hg blocks CSF production, even slow fluid drainage at high pressures should ultimately lead to ventricular collapse and severe artifact.

Brain↗
PubMed1989

Medulloblastoma with cartilaginous differentiation.

We describe the histologic, immunocytochemical, and electron microscopic features of a medulloblastoma containing cartilage that occurred in the left cerebellar hemisphere of a 57-year-old man. By light microscopy, highly cellular areas of the tumor typical of medulloblastoma showed evidence of both glial and neuroblastic differentiation. The tumor also contained foci of mature and immature cartilage. Transitions were observed between the cartilaginous foci and the more densely cellular regions of the tumor. No frankly teratomatous features or mesenchymal components other than cartilage were present. We postulate that the production of cartilage within this neoplasm most likely resulted from the metaplastic transformation of preexisting mesenchymal elements within the tumor or from multipotential neural crest-derived ectomesenchymal cells. Alternatively, the cartilage could have been produced directly by the neuroectodermal cells themselves, possibly related to a capacity for the latter to produce a chondroid ground substance.

Cartilage↗
PubMed1988

Safety and efficacy of chymopapain (Discase) in the treatment of sciatica due to a herniated nucleus pulposus. Results of a randomized, double-blind study.

A prospective, multiinstitutional, double-blind trial comparing the effect of chymopapain (Discase) vs. placebo (cysteine-edetate-iothalamate: CEI) for lumbar intervertebral disc rupture with sciatica was carried out on 173 patients, the largest such study reported to date. Patients were matched with respect to age, sex, physical habitus, and level of injection. The procedure was carried out under local anaesthesia. The success rate was superior in the chymopapain group regardless of the method used to assess outcome or the time over the first 6 months at which the two groups were compared: 71% vs. 45% if code breaks were analyzed at 6 months, and 67% vs. 44% if code breaks were defined as lost to follow-up. A single case of anaphylaxis and one case of septic discitis were the only serious complications noted. This study supports the role of chymopapain in the treatment of lumbar disc rupture with sciatica.

Adolescent↗
PubMed1987

Growth of 9-L and RT-9 gliosarcoma in female rats.

Published studies of 9-L and RT-9 gliosarcoma have been done only in male rats and it is widely assumed that these tumors do not grow in female rats. In this study 9-L and RT-9 gliosarcoma was inoculated into the brains of male and female Fisher CD rats. The tumors grew with essentially the same incidence and survival time in both sexes, confirming that female rats can be used as well as male rats in experiments using RT-9 and 9-L gliosarcomas.

Animals↗
PubMed1987

T2 and T3 sympathetic ganglia in the adult human: a cadaver and clinical-radiographic study and its clinical application.

The technique of percutaneous radiofrequency (RF) upper thoracic sympathectomy mandates an exact knowledge of the anatomical location of the sympathetic ganglia. Because conflicting descriptions are given in anatomy texts, we examined the T2 and T3 sympathetic ganglia in 48 sympathetic chains in adult cadavers to measure the exact location of the ganglia. Measurements were made relative to their distances (a) dorsal to the ventral surface of the vertebral body and (b) rostral or caudal to the midpoint of the vertebral body. Median locations of T2 and T3 ganglia were 17 to 20 mm dorsal to the ventral surface of the vertebral body and 2 mm rostral to the T1-T2 and T2-T3 vertebral bodies. The sympathetic chains lay lateral to and between the heads of the ribs at these levels. A clinical-radiographic correlation study of the sympatholytic effectiveness of various needle electrode placement sites during sympathectomy confirmed these findings. These data have been used to modify the technique of percutaneous RF sympathectomy.

Female↗
PubMed1986

Intracranial hypertension and cerebrospinal fluid production in dogs: effects of furosemide.

A method using chronically prepared, anesthetized dogs was devised for studying the effects of treatments of intracranial hypertension induced by applying a reversible extradural mass lesion while simultaneously measuring production of cerebrospinal fluid. This was measured with a ventricular-cisternal perfusion technique in which the rate of cisternal outflow could be controlled by a pump and matched to the inflow, allowing intracranial pressure to fluctuate despite simultaneous measurement of cerebrospinal fluid formation. Elevations of intracranial pressure to the range 20 to 35 Torr were induced and maintained during perfusion, but elevations above 35 Torr would not permit continued perfusion. At normal intracranial pressure, 10 Torr or less, rates of cerebrospinal fluid formation were the same whether the outflow controlling pump or free outflow was used. Formation of cerebrospinal fluid decreased progressively as intracranial pressure increased above 20 Torr. It also decreased with time after the start of perfusion during the course of 5 h, but returned to the initial range during the control phase of subsequent experiments in the same animal. Furosemide, 3 mg kg-1, i.v., had no significant effect on rate of formation but did induce a small decrease in ICP in time-controlled experiments in which i.v. fluid replacement limited net fluid losses to 20 ml kg-1 with no change in mean arterial or central venous pressures.

Animals↗
PubMed1986

Synergistic effect of methotrexate and radiation on gliosarcoma in tissue culture and in rats.

In vitro and in vivo studies were performed on rat gliosarcoma cells (RT-9) to investigate the synergistic effect of methotrexate and radiation against malignant brain tumors. For in vitro study, RT-9 cells were cultured on microtiter plates and treated with methotrexate, radiation, or both. For in vivo study, the cells were implanted into the cerebrums of CD-Fischer rats, and intraperitoneal methotrexate, whole brain radiation, or both were given. Although synergistic suppression of cell growth with combined therapy was observed in the in vitro study, synergism was less clearly demonstrated in tumor-bearing rats because of systemic toxicity of the therapy.

Animals↗