Biomedical subjects
Publications and source records attributed to R H Lye.
Surgery may contribute significantly to the management of intracranial neoplasms. It helps establish the diagnosis and provides palliation or even cure in selected cases. This article evaluates the present role of surgery, details some of the techniques involved with their associated complications and gives the expected outcome for certain types of tumour.
Brain slices were prepared from rats which had previously sustained a focal cerebral ischaemic insult as a consequence of middle cerebral artery occlusion. Slices cut in the coronal plane at the level of the anterior commissure were equilibrated for 1 h at 35 degrees C in a submersion chamber perfused with oxygenated artificial cerebrospinal fluid. A 4M K acetate-filled glass microelectrode (15-30 M omega) was used to penetrate each slice at multiple sites in order to record spontaneous neuronal activity. Subsequently, the presence of an area of cerebral infarction in the slices was confirmed using tetrazolium salt stains. Spontaneous neuronal activity, mainly as spike discharges or depolarisation, was observed in slices prepared from lesioned (6), sham-operated (6) and control (6) animals. The bursts of discharges were more consistently obtained and of larger amplitude and duration in the slices with focal areas of ischaemia when compared with the shams and controls. These observations may be of relevance to the hypothesis that excitotoxic discharges of disinhibited neurones contribute to the pathophysiology of stroke.
The authors describe the case history of a patient who was stabbed in the back of his neck with a knife and who later presented with a Brown-Séquard syndrome attributable to cervical spinal cord damage. Myelography and CT revealed a compressive extradural lesion shown at exploratory operation to be a loculus of cerebrospinal fluid (CSF). The loculus had formed as a consequence of leakage of CSF through a dural tear caused by the knife. Evacuation of this loculus resulted in some neurological improvement. The necessity of obtaining a clear history and of performing a thorough clinical examination is explained. The need to admit patients in whom stab wounds of the neck have transgressed subcutaneous fat is reiterated. Early referral to a neurosurgeon is advised for those patients with neurological deficits.
Aneursymal subarachnoid haemorrhage is frequently complicated by non-haemorrhagic deterioration. HLA typing was studied in a group of 40 patients who had sustained an aneurysmal subarachnoid haemorrhage in order to assess its ability to identify those who are likely to experience non-haemorrhagic deterioration. The antigen HLA-B7 appeared to be associated with an increased likelihood of this event supervening. Conversely, the antigen HLA-DR3, seemed to exert a "protective" influence.
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Although intracranial obliteration or detachable balloon occlusion of the proximal artery has been recommended for treatment of unruptured aneurysms of the cavernous sinus, carotid artery ligation continues to be used by many neurosurgeons. This study compares the long term outcome after carotid ligation with that following conservative treatment. Nine of 13 patients treated by common carotid ligation improved, two were unchanged but two patients subsequently needed internal carotid ligation (mean FU 8.2 years). Ten patients were managed conservatively. Three improved, six were unchanged and one patient died following intracranial haemorrhage (mean FU 6.9 years). The authors conclude that carotid ligation remains an acceptable method for treating these difficult lesions.
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This study examined the effects of two stabilised analogues of TRH, RX 77368 and CG 3509, in a rat cerebral ischaemia model produced by unilateral occlusion of the middle cerebral artery. The analogues were given intraventricularly after artery occlusion. The extent of the cortical ischaemia was evaluated after 10 days by somatosensory evoked potential (SEP) recording, followed by tetrazolium staining of brain slices for NADH-diaphorase activity. RX 77368 (2 X 10 micrograms; 15 min, 24 h) significantly improved the survival rate, protected the SEP and reduced the area of infarct. In contrast, neither a smaller dose of RX 77368 (2 X 3 micrograms) nor a 4 h delay in the treatment had any significant beneficial effects. Although CG 3509 (2 X 10 micrograms) resulted in an apparent improvement in survival, its overall effects were not statistically significant. The findings indicate that stabilised TRH analogues may have beneficial effects when given to animals with focal cerebral ischaemia.
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Clivus meningioma is an uncommon tumour arising from the region of the synchrondrosis between the basal portions of the sphenoid and occipital bones. We report a case of a patient with a large meningioma of the clivus whose presenting symptom was auditory change. Alteration of hearing is a rare mode of presentation for such a tumour although it may present at a later stage in about 50 per cent of cases. The discrepancy between the size of the tumour and the paucity of physical findings, the value of a multiple test auditory screening strategy, and the surgical approach in this case are discussed.
Magnetic resonance imaging (MRI) was performed in 20 patients with evidence on computed tomography (CT) of 21 acoustic neuromas before and after intravenous administration (0.1-0.2 mmol/kg body weight) of gadolinium-diethylene-triamine-pentaacetic acid (Gd-DTPA). Multi-section spin-echo (SE) sequences of varying repetition (TR) and echo (TE) times were performed in the transverse and coronal planes with a section thickness of 10 mm. All acoustic neuromas displayed marked enhancement on the T1-weighted (short TR/TE) SE sequence post-Gd-DTPA. The intrameatal component was particularly well demonstrated compared with non-enhanced magnetic resonance (MR) images and contrast-enhanced CT. Identification of intrameatal tumour was difficult on T2-weighted SE images and one tumour was not identified on the T1-weighted SE sequence prior to Gd-DTPA. Four of five intrameatal tumours measuring less than 8 mm could only be demonstrated on CT by using CT air meatography. Extrameatal tumour extension was demonstrated on contrast-enhanced CT, although the assessment of brain-stem involvement and displacement was not as clearly seen as on coronal MR images. In two patients with large acoustic neuromas and a cyst, the true relationship of the cyst to the tumour could only be identified on the post-Gd-DTPA scan. Magnetic resonance imaging with gadolinium-DTPA is a relatively quick, safe, well tolerated and effective method for the diagnosis of acoustic neuroma.
Computerised axial tomography (CT) and magnetic resonance imaging (MRI) should make detection of small trigeminal Schwannomas easier. Review of histories of five patients with trigeminal Schwannomas suggests that CT (and in one patient MRI) does not appear to lead to earlier detection of these tumours. Despite the availability of CT, three patients presented with large Schwannomas. A high index of clinical suspicion remains crucial to the diagnosis. Recent advances in diagnostic radiology have, however, considerably facilitated the logical planning of the operative approach. In that respect, it may be anticipated that the prognosis for these rare tumors will be improved.
The authors describe the case history of a patient who suffered a subarachnoid haemorrhage originating from an ependymoma of the fourth ventricle. The unusual nature of this presentation is emphasised in their review of a series of 22 patients with ependymomas of the craniocervical junction.
A method for quantitative assessment of severity of movement disorders using video recordings and computer analysis is presented. It allows quantified comparison of pre- and post-treatment conditions.
Bradykinin (BK) initially produced concentration-related relaxations of human basilar artery in vitro. Concentration-effect curves constructed at 2 h intervals to BK over an 8 h period were reproducible. The rank order of potency of three kinins on the human basilar artery was found to be BK greater than methionyl-lysyl-BK greater than des-Arg9-BK. The B2-receptor antagonist Thi5,8, D-Phe7-BK but not the B1-receptor antagonist des-Arg9-Leu8-BK selectively blocked BK-induced relaxations of the human basilar artery. The relaxant effects of bradykinin and acetylcholine but not papaverine were attenuated after removal of the endothelium or treating the tissues with BW755C. Indomethacin was without effect. Concentration-effect curves to angiotensin I were markedly attenuated by captopril at a concentration which had no effect on BK, angiotensin II or 5-hydroxytryptamine responses. It is concluded that BK induced relaxations of the human basilar artery are mediated via activation of a B2 receptor and the response is dependent upon the release of a factor present in the endothelium. Angiotensin converting enzyme is present in the human basilar artery and is important for the conversion of angiotensin I to angiotensin II but apparently not for the degradation of BK. It is likely that other kininases are present and active in the tissue.
There is a need for objective evaluation of the effectiveness of treatment of spasmodic torticollis so that comparisons can be made between different therapies. Video tape recordings of patients undergoing surgery for spasmodic torticollis were digitized and the movement of a reference marker was tracked by computer. A graphic presentation of oscillation of the marker around a mean position was obtained. Comparison of preoperative and postoperative recordings enabled assessment of the effectiveness of surgery. The results can be tabulated, facilitating accurate documentation of large series of results in publication. This should enable easier comparison of the effectiveness of different therapies.
This study examined the effects of permanent, unilateral cerebral artery occlusion on the somatosensory evoked potential (SEP) recorded from the ipsilateral cortex in the anaesthetised rat. Ten days after artery occlusion the SEP was absent in the majority of rats tested and in the remainder the wave amplitude was reduced compared to the potential recorded from the normal hemisphere but latency was unaffected. Histochemical staining with Tetrazolium for infarct size has shown that loss of the SEP correlated with ischaemic damage to the cortex. SEP recording can be used to assess the extent of cortical ischaemia in this small animal model.
Intravenous digital subtraction angiography was undertaken in 121 patients with known intracranial aneurysms. Its role in the management of these patients and its diagnostic accuracy have been assessed.