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Biomedical subjects

H B Coakham

Publications and source records attributed to H B Coakham.

At least 37 records · Page 2Linked to original sources
PubMed1997

Second-look surgery for incompletely resected fourth ventricle ependymomas: technical case report.

OBJECTIVE AND IMPORTANCE: The prognosis for patients with ependymomas is related to the adequacy of surgical clearance. It is, however, often not possible to obtain a macroscopically complete resection of tumors arising in the posterior fossa. This may be because of the involvement of structures, the sacrifice of which would result in unacceptable morbidity, or because of metastatic lesions at diagnosis. For those patients in whom initial surgery was incomplete, elective second-look surgery may allow more complete clearance of tumor. INTERVENTION: We have performed second-look surgery for fourth ventricle ependymomas in five patients: two women, aged 26 and 27 years, and three male patients, aged 4 months, 19 months, and 18 years. The 19-month-old male patient underwent early second-look surgery without receiving any interim chemotherapy. Second-look surgery on the other four patients was performed after they had received chemotherapy. No additional major morbidity was associated with the subsequent surgery, which achieved macroscopically complete clearances in four of the five patients. Three of four patients who underwent macroscopically complete resections were well, without clinical or radiological evidence of recurrent tumor, at 23, 25, and 34 months after their second operations. The 10-month-old patient who underwent early second-look complete resection relapsed locally at 33 months after surgery. Complete resection was not possible in one patient who had progressive tumor 8 months after second-look surgery. CONCLUSION: For patients in whom complete excision of fourth ventricle ependymomas is not possible at initial surgery, second-look procedures may enable macroscopic clearance to be achieved with little morbidity. A larger study is needed to evaluate this approach to treatment.

Adolescent↗
PubMed1997

Teflon-induced granuloma following treatment of trigeminal neuralgia by microvascular decompression. Report of two cases.

The authors report two cases of Teflon-induced granuloma occurring as a result of microvascular decompression using Teflon wool for the treatment of trigeminal neuralgia (TN). Teflon, which is used to separate a compressing vessel from the root entry zone (REZ) of the trigeminal nerve at the brainstem, is presumed to be an inert material. In the two cases reported here, however, Teflon induced a foreign body reaction at the REZ, causing recurrence of TN. The patients' pain was cured by complete decompression or partial sensory rhizotomy of the trigeminal sensory root at reoperation. Teflon-induced granuloma has occurred in 1.3% of the authors' series of 155 patients with TN treated using microvascular decompression. Recommendations for avoiding this complication are offered.

Aged↗
PubMed1996

Intra-operative image guidance in otolaryngology--the use of the ISG viewing wand.

The ISG viewing wand is an intra-operative guidance system with a proprioceptive robotic-like jointed arm. It provides surgeons with almost instantaneously reconstructed computer-generated CT or MRI images in two or three dimensions and can correlate any point within the operative field to its corresponding locus on the reformatted scan images. In addition to having been used in over 400 neurosurgical patients in Bristol, 14 patients with skull-base, cerebello-pontine angle or temporal bone lesions have also undergone wand-guided resections. The wand has proved to be particularly useful in pre-operative planning, allowing minimally-invasive incisions, providing per-operative navigation, identifying the relationship and proximity of important anatomical structures and in assessing the extent of lesion resection. We illustrate the advantages of intra-operative image-guidance by discussing four cases. The potential applications of this form of imaging technology to other otolaryngological procedures are discussed.

Adult↗
PubMed1995

Congenital astroblastoma: an immunohistochemical study. Case report.

Astroblastoma is a rare type of glial tumor, usually occurring in older children and young adults. It has a distinctive histological appearance that is characterized by a radiating arrangement of tumor cells that form perivascular pseudorosettes. The authors report only the second case of astroblastoma presenting in congenital form. Following subtotal tumor resection, the infant received 10 courses of chemotherapy consisting of vincristine, etoposide, and carboplatinum. Evidence is presented for a tumor response to chemotherapy, a previously unreported observation. The child is alive 2.5 years after diagnosis with satisfactory functional status. Immunohistological and ultrastructural features of this tumor are presented. The discussion focuses on the biology, natural history, and management of this unusual neoplasm.

Astrocytoma↗
PubMed1995

Functional outcome in patients after excision of extracanalicular acoustic neuromas using the suboccipital approach.

An audit of surgery for acoustic neuroma was carried out to determine the frequency and nature of postoperative symptoms and their impact upon the patient's quality of life and vocation. Fifty-six patients were interviewed between 6 months and 5 years (mean 26 months) after surgical excision of an acoustic neuroma. The objective surgical results in these patients are good, with normal or near normal functional preservation rates of 80% for the facial nerve (House-Brackmann grade I/II), and 27.3% for a previously functioning acoustic nerve. Despite this there was no significant overall reduction in the reported occurrence of balance problems, tinnitus, headache and other neurological sequelae of the tumour after surgical excision. In 20% of the patients persistent symptoms, including deafness and facial weakness, had prevented the resumption of former social activities. As a result of these symptoms 8.6% of the patients were certified medically unfit for work, but of those employed preoperatively over 70% had returned to their jobs. The success of neuro-otological surgical management of acoustic neuroma is offset by some degree of chronic morbidity. Our patients expressed the need to know whether their symptoms would resolve, but were often too afraid to ask. Patients can be reassured that the majority resume their former social and vocational activities, but should be advised that some symptoms can persist or occur de novo after surgery. Our data suggest that early intervention would reduce the incidence of these troublesome sequelae.

Adult↗
PubMed1994

Decline in incidence of medulloblastoma in children.

BACKGROUND: Medulloblastoma is one of the most common intracranial tumors in children. The perception that the incidence of this tumor has declined is reinforced by a decline in enrollment to international trials for the disease. METHODS: A retrospective population-based study of children younger than 15 years whose brain tumors were reviewed histopathologically was performed in the county of Avon, in the southwest region of England from 1976 to 1991. Then, the incidence of medulloblastoma was studied in the noncontiguous southwest and northern regions of England, with a combined childhood population base of 20.0 million child years for the period 1976-1991. RESULTS: In Avon, 16 children with medulloblastoma presented in the period 1976-1984 and 2 in the period 1985-1991, representing a decrease in incidence from 9.6 per million per year to 1.7 per million per year. The incidence of medulloblastoma in the combined southwest and northern regions showed a significant (P = 0.006) decline from 5.5 per million per year in the period 1976-1984 to 2.8 in the period 1985-1991. Considered individually, the decline in the southwest (from 6.2 per million per year to 2.8 per million per year) was significant but that in the Northern region (from 4.7 to 2.7) was not. CONCLUSIONS: In this report, a decline in the incidence of medulloblastoma was shown. In a recent case control study, a protective effect of maternal folate, iron, and multivitamin supplementation against primitive neuroectodermal tumors, including medulloblastoma was found. The introduction of periconceptional multivitamin supplementation in the 1980s may have caused this significant decline in the incidence of medulloblastoma.

Adolescent↗
PubMed1994

Pathological findings associated with trigeminal neuralgia caused by vascular compression.

Vascular compression of the trigeminal nerve root accounts for more than 80% of intractable cases of trigeminal neuralgia, but the pathogenesis is still debated. The authors report the ultrastructural changes in the trigeminal nerve root of a patient with trigeminal neuralgia, at the point of compression by a large, medially placed petrosal vein, and compare these with the findings in six cases of trigeminal neuralgia not related to vascular compression. Vascular compression of the trigeminal nerve root was associated with focal loss of myelin and close apposition of the demyelinated axons with few intervening astrocytic processes. No inflammatory cells were present. Immunoelectron microscopy for glial fibrillary acid protein confirmed that astrocyte processes were largely confined to the periphery of the lesion. Of the other six rhizotomy specimens, only one, from a patient with multiple sclerosis, showed demyelination with intervening astrocyte processes, perivascular lymphocytes, and lipid-laden macrophages. These findings support the hypothesis that ephaptic transmission plays a role in the pathogenesis of trigeminal neuralgia related to vascular compression.

Adult↗
PubMed1994

Advances in image-directed neurosurgery: preliminary experience with the ISG Viewing Wand compared with the Leksell G frame.

Because of the limited application of frame-based stereotaxy to general neurosurgical procedures, we have carried out a preliminary evaluation of the ISG Viewing Wand, a frameless image-directed surgical system that is based on the rapid reformat and accurate three-dimensional reconstruction capability of parallel processor-based computer technology. We have compared the first 36 cases carried out with the system in the Frenchay Neurosurgery Department with a retrospective analysis of the previous 36 cases carried out using the Leksell G frame. The stereotactic cases were completed over a period of 15 months, representing 2.8% of intracranial procedures. The wand cases were completed in 3 months, 13% of the intracranial practice during that time. The wand was used for 28 supratentorial craniotomies (76%), four infratentorial procedures (11%) and five biopsy procedures (13%). Conventional stereotaxy was not used for posterior fossa or skull base procedures. Supratentorial craniotomy was carried out in nine cases (25%), while the remaining 27 cases involved point source localization within the cranium (75%). The mean preparation time prior to surgery was 65 min for the stereotactic cases and 37 min for the wand cases. We therefore conclude that the indications for frame-based stereotaxy and Viewing Wand use are mutually exclusive. Leksell stereotaxy remains the method of choice for point source localization deep within the cranium. All other procedures requiring an image-directed minimally invasive surgical approach are more appropriately carried out using the Viewing Wand. The system has potential immediate application in supratentorial, skull base and infratentorial tumour surgery, vascular surgery, epilepsy surgery and upper cervical spine surgery.

Brain Mapping↗
PubMed1993

Giant aneurysm of internal carotid artery in a four-year-old child: a case report.

A case of giant saccular aneurysm in early childhood is reported. An internal carotid aneurysm presenting with episodic headache was successfully clipped with complete relief of symptoms. The patient was also investigated for a possible collagen deficiency which proved negative. Clinical features and pathogenesis of this rare lesion are discussed.

Carotid Artery Diseases↗
PubMed1993

Treatment of recurrent and cystic malignant gliomas by a single intracavity injection of 131I monoclonal antibody: feasibility, pharmacokinetics and dosimetry.

A pilot study was undertaken to determine the feasibility of infusing 131I labelled monoclonal antibodies (MoAbs) into either the cavity remaining after resection of malignant glioma or into glioma cysts. Of the seven patients recruited into the study, two had cystic lesions and five resection cavities. Six of the seven were treated after relapse from primary therapy. All patients apart from one, were given a single injection of 131I conjugated to a MoAb (ERIC-1) recognising the human neural cell adhesion molecule (NCAM). One patient received a further injection of 131I-MoAb after regrowth of their disease. Pharmacokinetic studies revealed that the MoAb remained predominantly in the tumour cavity with little leakage into the systemic compartment. This resulted in a high calculated dose of radiation being delivered to the tumour cells either lining or within close proximity to the cavity/cyst wall. In such a small study, it is not possible to determine accurately response rates, but individual patient responses were observed. This, along with the low toxicity noted, demonstrates the feasibility of using 131I-MoAbs in this way. With 131I, radiation dose is deposited in tissue to a depth of 1 mm from the source. The possibility of applying isotopes such as 90Yttrium which will irradiate tumour/tissue to a greater depth (6 mm) is discussed in context with the biology of glioma infiltration into normal brain parenchyma.

Adolescent↗
PubMed1992

The cytotoxic action of lymphokine activated killer cells upon the human glioma cell line U251 is stimulated by bispecific monoclonal antibody (MoAb) constructs.

The ability of IL-2 stimulated mononuclear cells to kill the human glioblastoma cell line U251 has been investigated. Highest cytotoxic activity was generated in low cell density cultures incubated for 15 days with 250-1000 U/ml IL-2. Sub-optimal killing was noted, with cells only exposed to IL-2 for three days. Under the latter conditions, bispecific monoclonal antibodies (MoAbs) of either anti-CD3 or anti-CD16 and an anti-NCAM MoAb stimulated LAK cell activity markedly. Anti-CD16 conjugates were found more effective than anti-CD3 and (Fab')2 constructs more efficacious than those made with whole Ig molecules. Maximal stimulation of LAK cell activity was noted with bispecific MoAbs. Little effect was observed with either single or mixtures of monomeric MoAbs. Furthermore, no effect of bispecific MoAbs was observed when target cells lacked expression of NCAM. These results could be of clinical importance as it is not always feasible to screen LAK cells for optimal activity before administration to patients. Whilst bispecific MoAbs have no effect on optimally stimulated LAK cells, they are not inhibitory and can stimulate killing under sub-optimal IL-2 stimulation.

Antibodies, Monoclonal↗
PubMed1992

Epithelial differentiation in gliomas, meningiomas and choroid plexus papillomas.

The immunohistological findings using antibodies to different intermediate filaments (glial fibrillary acidic protein, vimentin and two types of cytokeratin) and epithelial membrane antigen are described in 89 gliomas, 19 meningiomas and 8 choroid plexus papillomas (CPPs) from adult patients. All the patients had total or subtotal surgical excision of their tumours with clinical follow up for between 3 and 7 years. The immunohistological results were correlated with the histological features and patient survival. Tumours other than low grade astrocytomas, oligodendrogliomas and anaplastic ependymomas expressed one or more epithelial markers. This immunohistological evidence of epithelial differentiation in the absence of histological epithelial features in gliomas confirms that the two are not necessarily correlated. It is concluded that the expression of epithelial markers in some intradural tumours may reflect aberrant differentiation related to the degree of anaplasia in poorly differentiated astrocytomas and glioblastomas. All the patients with anaplastic epithelial marker-positive gliomas died within 1 year, whereas only 68% of patients with marker-negative tumours died within the follow-up period. In ependymomas and meningiomas, the expression of epithelial markers may reflect their histogenesis, while in malignant CPPs such expression could denote either their aberrant differentiation or histogenetic derivation.

Adolescent↗
PubMed1991

HLA-Dr expression by tumor cells compared with survival in high grade astrocytomas.

Frozen samples from 78 high grade astrocytomas were reacted with a monoclonal antibody directed against HLA-Dr invariant chain. Survival data was obtained for all 78 cases. HLA-Dr was expressed by a proportion of tumor cells in 65/78 (83%). Comparison of the survival of positive and negative cases showed that the difference was not statistically significant (p = 0.4). The relevance of the finding is discussed in the context of the immunoreaction to brain tumors.

Antigens, Neoplasm↗
PubMed1991

The monocyte/macrophage infiltrate in 35 medulloblastomas: a paraffin-wax study.

We have studied formalin fixed, paraffin-wax embedded tissue from 35 medulloblastomas, collected over 23 years (27 non-desmoplastic and 8 desmoplastic) with KP1 and Mac387 two monoclonal anti-monocytes/macrophage (M/Ms) antibodies recommended for use on paraffin wax embedded tissue. In non-desmoplastic medulloblastomas, outside areas of necrosis, M/Ms were detected in 50% of cases with KP1 and 52% with Mac387. M/Ms were seen in 100% of desmoplastic medulloblastomas with both antibodies. Semiquantitative assessment revealed that, on average, desmoplastic tumors had at least three times as many infiltrating M/Ms as non-desmoplastic tumors. There was no significant difference in the findings with the two antibodies or, between recently embedded and "older" tumors. The findings may be indicative of the presence of a host M/Ms immune response in medulloblastoma, which may be more accentuated in desmoplastic medulloblastomas. Furthermore, we conclude that these antibodies are quite suitable for the study of infiltrating M/Ms, thus lessening (but not obviating) the need for frozen tissue for immunohistological studies.

Antibodies, Monoclonal↗
PubMed1991

Characterization of the mononuclear cell infiltrate and HLA-Dr expression in 19 oligodendrogliomas.

We have studied frozen tissue from 19 oligodendrogliomas with a panel of antibodies to lymphocytes and their subsets, macrophages, natural killer cells, and HLA-Dr antigens. Macrophages were detected in moderate numbers in 60%-100% of tumors depending on the antibody used. T lymphocytes were fewer in number than macrophages and were present in 62% of cases. Most of the T lymphocytes were of the CD8 phenotype. CD4 lymphocytes were very few in number and present in only 18%. B cells and natural killer cells were absent from all cases. HLA-Dr antigens were expressed by macrophages in all cases but never on tumor cells. The implications of these findings are that macrophages and, to a lesser extent, CD8 lymphocytes are the predominant cells infiltrating oligodendrogliomas and that they may exert cellular immune functions.

Antibodies, Monoclonal↗