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Biomedical subjects

G D Parker

Publications and source records attributed to G D Parker.

16 recordsLinked to original sources
PubMed2003

Influence of bone invasion and extent of mandibular resection on local control of cancers of the oral cavity and oropharynx.

The aim of this paper was to evaluate the influence of bone invasion on treatment outcome among patients with cancers of the oral cavity and oropharynx and to determine whether or not outcome was influenced by the extent of mandibular resection. A review of 127 prospectively documented patients who were treated with marginal or segmental resection for oral (n = 110) and oropharyngeal (n = 17) cancers was undertaken. There were 97 males and 30 females with a median age of 61 years. Clinical T stages were: T1 17 patients, T2 33, T3 22, T4 55. Median followup was 4 years. A total of 94 patients underwent marginal resections and 33 underwent segmental resections. Histological bone invasion was present in 17 patients (16%) in the marginal resection group and 21 patients (64%) in the segmental group (P<0.05). Soft tissue surgical margins were positive in 11 patients (12%) in the marginal group and in seven patients (21%) in the segmental group (P=not significant). Local control did not correlate significantly with T stage, the extent of mandibular resection or the presence of histological bone invasion, but was significantly influenced by positive soft tissue margins (P<0.01). Among patients with bone invasion, the local control rate was higher following segmental resection when compared to marginal resections (87% vs 75%) but this was not statistically significant. Survival was significantly influenced by positive soft tissue margins but not bone invasion or the type of resection. We conclude that bone invasion alone did not predict for local control or survival rates among patients with oral and oropharyngeal cancers. Involved soft tissue margins were highly predictive of local recurrence and decreased survival. Conservative resection of the mandible is safe as long as marginal mandibulectomy does not lead to compromise of soft tissue margins. Segmental resection should be reserved for patients extensive bone invasion or those with limited invasion in a thin atrophic mandible.

Adult↗
PubMed1997

Vestibular abnormalities in charge association.

We report the vestibular abnormalities in 5 patients with the CHARGE association (Coloboma, Heart disease, Atresia of choanae, Retarded growth and development and/or central nervous system anomalies, Genital hypoplasia, and Ear anomalies). All patients had absent vestibular function as indicated by absent vestibulo-ocular reflexes and severe imbalance on simultaneous deprivation of proprioception and vision, as well as delayed motor development. All 6 semicircular canals were aplastic in each of the patients. While cochlear function was severely reduced in 6 of the 10 ears, it was absent only in 3 ears and was actually intact below 3 kHz in 1 ear. All 10 bony cochleas were present on computed tomography, and although 7 appeared abnormal, 3 appeared normal. This study confirms that absence of the bony semicircular canals in the presence of a bony cochlea is a characteristic finding in CHARGE association. It also demonstrates that these disproportionate structural abnormalities are reflected in the functional abnormalities: absent vestibular function with preservation of some cochlear function.

Adolescent↗
PubMed1996

Disturbance of central vision after carbon monoxide poisoning.

BACKGROUND: Cerebral achromatopsia is a disturbance of colour perception which may be complete or partial. CLINICAL RECORD: A 28-year-old male patient presented five months after carbon monoxide poisoning with achromatopsia. The achromatopsia was unaccompanied by an inability to recognise faces (prosopagnosia) nor was there any disorder of form or depth perception. RESULTS: Magnetic resonance imaging showed bilateral sharply defied areas of haemorrhagic infarction in the globus pallidus with extensive infarction involving temporal and occipital lobes and with apparent partial sparing of the visual cortex, presumably due to arterial insufficiency. The disturbance of central colour vision resolved spontaneously after a further period of 6 months. CONCLUSION: The symptom of achromatopsia is analysed with particular reference to the recent work of Professor Zeki on disturbance of central colour vision following CO poisoning and the unusual MRI findings.

Adult↗
PubMed1995

Vertebral artery dissection diagnosed with CT.

Vertebral artery dissection after neck manipulation has been well described. A case of bilateral vertebral artery dissection diagnosed with dynamic CT scanning of the neck is reported. The CT appearances and correlative angiographic and MR findings are presented.

Adult↗
PubMed1992

Investigation of the blood pressure levels of workers occupationally exposed to salt.

Publicity surrounding the salt and hypertension debate evoked fear in workers at a Salt Mine that their working conditions may lead to high blood pressure. A cross-sectional study was carried out to investigate the blood pressure levels of these workers. The blood pressure levels were found not to be raised in comparison with those of a similar group of workers not occupationally exposed to salt.

Adult↗
PubMed1991

Clinical-radiologic issues in perineural tumor spread of malignant diseases of the extracranial head and neck.

The radiologic and clinical records of 52 patients with radiologically documented perineural tumor were reviewed to assess the spectrum of tumors responsible, the nerves most commonly involved, and the optimal methods for imaging perineural tumor infiltration. Perineural tumor infiltration was most commonly seen with head and neck squamous cell carcinoma, followed by adenoid cystic carcinoma and several others, such as non-Hodgkin lymphoma, malignant schwannoma, minor salivary gland malignancy, and other sarcomas. The second and third divisions of the trigeminal nerve and the facial nerve were most commonly involved with perineural tumor. Both antegrade and retrograde perineural tumor spread were seen, although retrograde spread was significantly more common. Both high-resolution direct coronal computed tomography and magnetic resonance (MR) imaging clearly showed perineural tumor below the skull base. MR imaging best depicted skull base, cisternal, and brain stem perineural tumor infiltration. T1-weighted MR imaging before and after administration of gadopentetate dimeglumine is the study of choice in investigation of perineural tumor.

Cranial Nerve Neoplasms↗
PubMed1991

Radiologic evaluation of the normal and diseased posterior cervical space.

The posterior cervical space seen on cross-sectional imaging of the neck constitutes most of the posterior triangle seen on clinical examination. Although triangular anatomy relates best to the surface perspective of the clinician, a spatial approach to anatomy works better for the radiologist viewing axial images. The posterior cervical space is defined as the area in the posterolateral portion of the neck from the skull base to the clavicles deep to the sternomastoid and trapezius muscles but superficial to the prevertebral space. Its principal contents are fat, the spinal accessory nerve, and lymph nodes. We analyzed CT and MR images and clinical records of 63 patients known or suspected to have disease of the posterior cervical space to determine the imaging features that mark a lesion as originating in the posterior cervical space and the spectrum of diseases that arise there. Of the 63 patients in the study, four had clinical pseudomasses, nine had congenital lesions, 10 had inflammatory disease, six had benign tumors, and 34 had malignant tumors. A typical mass lesion of the posterior cervical space was centered within the fat of the space, between the deep and superficial layers of the deep cervical fascia. Characteristic displacements caused by a mass in the posterior cervical space included anteromedial displacement of the carotid space and posteromedial displacement of the prevertebral space. Our study shows that the differential diagnosis of lesions of the posterior cervical space reflects the normal contents of the space, and that diagnosis can thereby be predicted from knowledge of the normal anatomy and contents of the space.

Carcinoma, Squamous Cell↗
PubMed1991

Mortality of employees in plants manufacturing 4,4'-bipyridyl.

A historical-prospective cohort study was conducted of 729 male employees of plants manufacturing 4,4'-bipyridyl. The cohort was studied because employment in some of the plants had been linked to malignant and nonmalignant skin lesions attributed to exposure to tarry by-products. The overall mortality experience of the cohort did not show any statistically significant findings. More-detailed analysis of subdivision of the cohort gave results that justified further inquiry into lung cancer incidence. A nested case-referent study did not indicate that any occupational factor other than employment in a bipyridyl plant was related to the incidence of lung cancer. The epidemiologic, toxicologic, and industrial hygiene information was assessed, and it was concluded that there was no evidence of a plausible occupational hazard of lung cancer to the bipyridyl workers, but that a follow-up of the cohort after an interval of five years should be undertaken.

Cohort Studies↗
PubMed1990

Cervical myelopathy in C.P.P.D. deposition disease.

Cervical Myelopathy is a rare manifestation of calcium pyrophosphate dihydrate (C.P.P.D.) deposition disease. A case is presented where radiographically noncalcified extradural masses containing C.P.P.D. crystals were present at the C7 level, producing cord compression and neurological symptoms. These masses are thought to represent para-articular deposits related to the adjacent facet joints.

Aged↗
PubMedDate not supplied

CT and MR imaging of fourth ventricular meningiomas.

True fourth ventricular meningiomas are rare. We report two cases, one with typical CT, angiographic, and magnetic resonance (MR) appearances and one with atypical features of central cyst formation on CT and MR. The utility of MR in demonstrating intraventricular location in three imaging planes is illustrated. Given the rarity of these tumors, atypical features may preclude accurate preoperative diagnosis, even with MR.

Adult↗
PubMedDate not supplied

Deflation of detachable balloons in the cavernous sinus by percutaneous puncture.

The authors show that percutaneous puncture of balloons within the cavernous sinus is technically feasible and allows further access to the cavernous sinus after balloon detachment. Complete closure of a large carotid cavernous fistula was achieved in the 37-year-old trauma victim they treated using this technique.

Adult↗