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Biomedical subjects

B K Willis

Publications and source records attributed to B K Willis.

27 records · Page 2Linked to original sources
PubMed1991

Neurenteric cysts of the posterior fossa: recognition, management, and embryogenesis.

Neurenteric cysts are endothelium-lined structures most commonly encountered in the lower cervical or upper thoracic spinal cord. The occurrence of neurenteric cysts within the cranial vault is unusual. We present three patients with neurenteric cysts located within the posterior fossa: one near the jugular foramen deforming the 4th ventricle, a second in the cerebellopontine angle, and a third in the prepontine cistern. Several different theories have been advanced to explain the embryogenesis of neurenteric cysts. We review these theories and conclude that cranial neurenteric cysts may arise from a disturbance of early gastrulation, shortly after the onset of primitive streak regression.

Adult↗
PubMed1988

Stereotactic interstitial brachytherapy of malignant astrocytomas with remarks on postimplantation computed tomographic appearance.

Seventeen patients were treated with stereotactically implanted high activity iodine-125 seeds, 12 patients for recurrent malignant astrocytomas (Protocol I) and 5 patients for newly diagnosed glioblastomas (Protocol II). Total radiation dosage to the recurrent tumors in Protocol I, including prior external beam irradiation, averaged 13,500 cGy. In the follow-up period of 6 to 50 months, the survival rate was 93% at 6 months, 60% at 12 months, 50% at 18 months, and 38% at 24 months after implantation. In Protocol II, brachytherapy was used as an interstitial radiation boost to the conventional treatment of newly diagnosed glioblastomas. External beam therapy and interstitial brachytherapy provided 11,000 cGy to these tumors. In the follow-up period of 15 to 27 months, there was a 100% survival at 12 months, 75% at 18 months, and 25% at 24 months after implantation. Eight of our 17 patients required reoperation for persistent or recurrent mass lesions at 6 to 15 months postimplantation; 7 were found to harbor masses of radionecrosis containing nests of anaplastic astrocytes; 1 had frank tumor recurrence. Median survival in this group of patients requiring reoperation was 18.7 months postimplantation. In a review of postimplantation computed tomographic scans, significant mass effect and crossover of hypodensity or enhancement into the corpus callosum or opposite hemisphere were found to have prognostic significance; persistent areas of contrast enhancement and excessive peritumoral hypodensity did not.

Adolescent↗
PubMed1987

Management of a large skull defect utilizing a vascularized free omental transfer.

A patient who underwent prior cranial surgery and radiation therapy and had the loss of his bone and skin flaps is presented. Basal cell carcinoma of a skin graft, placed on the dura mater and osteomyelitis of the surrounding cranium subsequently occurred. This problem of infection, neoplasia, cerebral protection, coverage, and cosmesis was managed successfully with a complex repair. The repair utilized autogenous fascia lata for the replacement of dura mater, rib and iliac crest bone for an autogenous cranioplasty, a free vascularized omental transfer for soft tissue bulk overlying the cranioplasty, and an autogenous split thickness skin graft over the omentum for coverage. Subsequent partial resorption of the autogenous cranioplasty necessitated the placement of a methyl methacrylate cranioplasty.

Adult↗
PubMed1986

The influence of trauma to the spleen on postoperative complications and mortality.

Although splenectomy has been associated with an increased risk of late sepsis, it is not clear whether splenectomy for trauma increases the incidence of acute infectious complications or deaths during the initial hospital stay. We reviewed the charts of 175 trauma patients who had exploratory laparotomy between July 1977 and June 1983. Eighty patients underwent total splenectomy and 15 patients had splenic salvage operations performed. A group of 80 patients with no splenic trauma (N.S.T.) who had laparotomy for trauma, served as a control group. These N.S.T. patients had injury severity scores (ISS) similar to the patients who had splenectomy. The incidence and types of postoperative complications, mortality rates, and length of hospitalization were similar for both groups, indicating that splenectomy was not associated with an increased risk of postoperative complications or mortality.

Adult↗
PubMed1986

Enchondroma of the cervical spine.

Enchondroma is a benign cartilaginous tumor rarely found in the vertebral column. The authors report a case of a 24-year-old woman with upper extremity paresthesias and weakness secondary to bony destruction of multiple vertebral bodies by an enchondroma. The tumor was treated by block excision of the involved vertebral bodies followed by placement of a bone graft.

Adult↗
PubMedDate not supplied

Mechanical extension of human hair and the movement of the cuticle.

Goniophotometry has enabled measurement of the angle that the surface of the cuticle (the scales) of a human hair fiber makes with the axis of the hair shaft. This measuring technique has been used to obtain the change of this scale angle with extension of a hair fiber under fixed conditions of temperature and relative humidity. Based on a simple model of overlapping scales of the hair cuticle, analysis shows that, for hair fibers extended to strains above 10% at 35% relative humidity and at 35 degrees C, overlapping scales become progressively detached from each other. This scale detachment has been suggested to result from the mechanical failure of the endocuticle layer in the scale structure. This endocuticle layer is low in disulfide cross-linking, which would result in a lowered stiffness and greater extensibility, as indicated by the higher swelling of the layer in water as against the highly cross-linked exocuticle layers. The greater extensibility of the endocuticle would also explain the greater distortion of this layer under stress, but it would not follow that endocuticular failure under stress should result. An alternative mechanism of failure of adhesion between overlapping scales in the cuticle is suggested, based on the involvement of the hydrophobic upper-beta-layer with its surface of 18-methyleicosanoic acid (18-MEA), which may provide mobility and a reduction in adhesion between scales. This potential failure of the cementing of the overlapping scale structure due to the 18-MEA is discussed, with particular reference to the standard permanent setting procedure of human hair.

Hair↗
PubMedDate not supplied

Treatment in patients with glioblastoma multiforme and poor performance status: is it worthwhile?

It has not been ascertained that treatment of glioblastoma multiforme of the brain (GMB) favorably alters the prognosis in patients with poor pretreatment performance status (PPS). We report on 52 patients with GMB and PPS. The mean survival of 43 treated persons was 19 +/- 12 months (95% confidence interval) and of nine untreated individuals, 2 +/- 1 months (p > 0.50); the corresponding survival rates at 1 year were 39 +/- 16% and 0% (p > 0.05) and at 2 years, 15 +/- 12% and 0% (p > 0.40). We recommend active treatment of patients with GMB even when they present with poor functional status.

Aged↗