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Biomedical subjects

P D Lees

Publications and source records attributed to P D Lees.

At least 19 recordsLinked to original sources
PubMed2002

Inflammatory hypophysitis - the spectrum of disease.

BACKGROUND: Inflammatory conditions of the pituitary are rare and consequently there are a number of single case reports of this condition but few reports of series. The condition is often divided into lymphocytic and granulomatous hypophysitis and it has been suggested that these two conditions represent the ends of a spectrum of disease. METHOD: We present our experience with 14 cases of this condition, correlating the presenting symptoms with the neuroradiology, surgical findings and subsequent histology. FINDINGS: The subjects (11 female 3 male) ranged in age from 13 to 64 years. Final histopathological diagnoses included 5 cases of lymphocytic hypophysitis, 4 cases of Rathke's pouch cyst with granulomatous response, 2 cases of granulomatous hypophysitis and 1 case with an inflammatory process that did not fit the current classification. Two subjects did not undergo surgery. Headache was a presenting feature in 11 of 14 cases and fever in 3 of 14 cases. Length of symptoms prior to presentation varied from acute onset to 9 years. One case of lymphocytic hypophysitis was associated with pregnancy. Evidence of hypopituitarism was present in 9 of 10 subjects assessed preoperatively. Preoperative radiology showed three patterns of disease: A cystic appearance was common with low signal content on MRI T1 weighting with an enhancing ring and a thickened enhancing stalk (5 patients). 4 patients showed a solid enhancing mass. A third group (2 patients) showed cysts with high signal content on T1 weighting - both of these were Rathke's cysts on histology. INTERPRETATION: Overall there were no striking features in the clinical presentation to distinguish pituitary inflammation from pituitary adenoma. The prognosis was generally good.

Adenoma↗
PubMed2001

Chromosomal aberrations in sporadic pituitary tumors.

Pituitary adenomas are common intracranial neoplasms that may be hormone-secreting or nonfunctional. Genetic defects associated with some pituitary tumors have been identified, although our understanding of the underlying molecular mechanisms remains incomplete. We have studied 75 sporadic pituitary tumors, representing the major clinical subtypes, by comparative genomic hybridization (CGH) with the aim of assessing for DNA copy number changes. CGH revealed chromosomal imbalances in 34 adenomas (45.3%), whereby gains were 4.9 times more frequently observed than losses. Most of the genetic alterations detected by CGH affected entire chromosomes (108/131, 82.4%). Gain of genetic material was observed predominantly on chromosomes X (24/75, 32%), 19 (12/75, 16%), 12 (6/75, 6.7%), 7 and 9 (5/75, 6.7%), whereas loss of DNA sequences most frequently affected chromosomes 11 (4/75, 5.3%), 13 and 10 (3/75, 4%). There were no significant differences in the CGH results for the individual clinical subtypes of pituitary tumors. These results reveal a nonrandom pattern of chromosomal alterations in pituitary tumors, in particular gains of entire chromosomes, and this may contribute to the development of such neoplasms.

Adenoma↗
PubMed1997

A nationwide study to investigate current opinion amongst maxillo-facial and neurological surgeons with regard to access surgery for neurosurgical procedures.

Over the past two decades there has been much interest in the use of craniofacial disassembly techniques to improve difficult access to some neurosurgical lesions, However, it is not known to what extent these techniques have been adopted throughout the UK. The aim of this study was to establish how many maxillofacial surgeons and neurosurgeons are currently involved in this type of collaborative surgery and to determine current opinion regarding the use of these procedures. A self-completion questionnaire was sent to all consultant maxillofacial surgeons and neurosurgeons within the UK. The results of the questionnaire suggest that there is a high level of interest in this type of collaborative surgery within the UK. It has demonstrated some interesting differences of emphasis regarding possible advantages and disadvantages of these procedures, and the areas to which access can be particularly improved. In addition, the future of this type of collaborative surgery and some of the difficulties involved in its organization were highlighted.

Attitude of Health Personnel↗
PubMed1996

The orbitozygomatic infratemporal fossa approach: a quantitative anatomical study.

Using detailed cadaveric dissections this study has demonstrated and quantified the increase in exposure and additional access gained by using the orbitozygomatic infratemporal fossa approach for neurosurgical access. The surgical window of exposure can be increased by up to 300% when this technique is utilised to facilitate access via either a subtemporal (to access the P2 segment of the posterior cerebral artery) or transsylvian (to access the basilar bifurcation) approach. In addition the distance between the surgeon and the operative field can be decreased by approximately 2-3 cm. The orbitozygomatic infratemporal fossa approach is a relatively simple technique which can readily increase neurosurgical exposure of the skull base. It also provides simultaneous access to the infratemporal fossa, pterygopalatine fossa and the orbit.

Craniotomy↗
PubMed1995

The transzygomatic approach: a long-term clinical review.

The transzygomatic approach has been utilised to improve access to the skull base, infratemporal fossa and orbit for a number of years. It provides a low anterolateral approach to the skull base, along the floor of the middle fossa. It allows both a transsylvian and subtemporal approach with a reduction in brain retraction and better exposure of adjacent neurovasculature structures. A long term review of 53 patients is presented highlighting outcome at two years post surgery and morbidity of the approach. It is concluded that the technique is versatile and can be used to improve exposure of a variety of anatomical locations. There is minimal long term morbidity attributable to the surgery of access and the majority of patients have had good outcomes.

Adolescent↗
PubMed1995

A good wife, but never a mother....

Prolactinomas are the commonest pituitary tumour. They are more frequent in women and account for up to 15% of patients with amenorrhoea (through secondary gonadotrophin suppression). Here we present two patients with previously unrecognized giant prolactinomas, one of whom is probably unique in having radiological evidence of progression from micro to macro prolactinoma in the absence of treatment. Both were being considered for hormone replacement therapy. These tumours are known to be oestrogen sensitive and potentially life threatening. Both had been investigated for amenorrhoea prior to the availability of prolactin assays; no other cause had been found. Amenorrhoeic patients investigated prior to the early 1970s should be reviewed with this in mind. Patients with untreated microprolactinomas should probably be monitored indefinitely.

Amenorrhea↗
PubMed1994

A modified frontal approach for anterior circle of Willis aneurysms.

A new approach to anterior circulation aneurysms is described in which the position of the surgeon is radically different from usual, allowing an enhanced view along the plane of the parent artery with minimal retraction and proximal control. The position of the surgeon and assistant are comfortable, and the scrub nurse's access to the surgeon's hands is greatly enhanced.

Carotid Artery, Internal↗
PubMed1994

Intrasellar pituitary tissue pressure, tumour size and endocrine status--an international comparison in 107 patients.

In a two-centre study, intrasellar pituitary tissue pressure was measured at transsphenoidal surgery in 107 patients with pituitary adenomas or intrasellar cysts. 'Normal' ISP in patients under anaesthesia with small microadenomas (< 5 mm diameter) or a partial empty sella was 12 +/- 3 mmHg. Raised ISP (> 15 mmHg) was found in 75% of cases. The highest pressures were recorded in tumours with parasellar invasion (30 +/- 2; p < 0.01) irrespective of size and extension in other directions. In non-invasive lesions there was no correlation between the level of raised ISP and tumour size. Hypopituitarism and stalk compression syndrome were both associated with higher ISP than patients with normal pituitary function.

Adenoma↗
PubMed1992

Blood flow in portal systems with special reference to the rat pituitary gland.

Regional pituitary blood flow has been studied in adult female Fischer 344 rats by [14C]iodoantipyrine autoradiography. A general mathematical solution has been derived to allow the calculation of blood flow in the second compartment of a portal system and the proportion of blood "shunted" through the first compartment without exposure to tissue uptake from a knowledge of (a) the volume ratios of the two compartments, (b) the tissue tracer uptakes of the two compartments, and (c) the arterial tracer concentration with respect to time of a freely diffusible tracer. Significant diffusion limitation and/or arteriovenous shunting has been demonstrated in the neurohypophysis, suggesting that the majority of incoming blood is "shunted" unchanged to the adenohypophysis. The mean value of the shunt is 89% (range of 84-93%) for the median eminence and lies between 72% (range of 52-82%) and 73% (range of 59-81%) for the posterior pituitary. Neurohypophysial flow rates of 1.20 (range of 0.99-1.55) ml g-1 min-1 for the median eminence and 1.68 (range of 0.83-3.53) ml g-1 min-1 for the posterior pituitary were measured. These values represent "tissue-available" (nonshunted) flow; estimated mean total (shunted plus nonshunted) neurohypophysial flow rates were 11.7 (range of 9.5-17.5) ml g-1 min-1 for the median eminence and 6.1 (range of 3.1-8.9) ml g-1 min-1 (minimum) for the posterior pituitary. Adenohypophysial blood flow is heterogeneous. In the long portal territory, the flow rate was 1.18 (range of 0.95-1.75) ml g-1 min-1 but short portal territory flow calculation is complicated by an unquantifiable nonportal venous drainage; using the natural limits of zero and 100% gives a minimum adenohypophysial flow rate of 1.42 (range of 0.76-2.07) ml g-1 min-1 and a maximum value of 1.97 (range of 1.03-2.82) ml g-1 min-1.

Algorithms↗
PubMed1992

The zygomatico-temporal approach to the skull base: a critical review of 11 patients.

The zygomatico-temporal approach to the base of the skull is a relatively new but established surgical technique. The approach involves the removal of the zygomatic bone to provide access to the skull base, middle cranial fossa, parasellar region and interpeduncular cistern with minimal brain retraction. An excellent view of the bifurcation of the basilar artery and suprasellar region is provided. The outcome of 11 patients undergoing this procedure is reported with particular reference to the post-operative morbidity and the cosmetic result.

Adenoma↗
PubMed1987

Subdural empyema: a rational management plan. The case against craniotomy.

A review of the management of 34 patients with subdural empyema treated at the Derbyshire Royal Infirmary has been undertaken. It is concluded that craniotomy has little part to play in the management of patients with this condition. With modern, improved antimicrobials and prompt burr hole lavage complete recovery should be obtained in the majority of cases. The treatment of the severely ill patient is discussed.

Adolescent↗