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Biomedical subjects

L Symon

Publications and source records attributed to L Symon.

At least 181 records · Page 10Linked to original sources
PubMed1982

Conduction of sensory action potentials across the posterior fossa in infratentorial space-occupying lesions in man.

Central conduction time following median nerve stimulation has been recorded in 28 patients with infratentorial space occupying lesions. Fourteen of these (50%) showed a prolonged central conduction time, which invariably involved that segment of the conduction time between the dorsal column nuclei generators and the generation site for P15, which we believe to be the upper brain stem or thalamus. Three other cases showed prolongation of the N14-P15 segments though total central conduction time was within normal limits. One case with marked hydrocephalus showed prolongation both before and after the P15 wave. The possible pathophysiology of prolongation of central conduction time in these cases and the possible neural generation site of P15 are discussed.

Brain Neoplasms↗
PubMed1982

Recurrence of pituitary adenomas after transcranial operation.

A series of 289 pituitary adenomas operated upon transcranially have been assessed for the frequency of recurrence. Ten patients died in the postoperative period, and nine patients have been lost to follow up. Follow up data is therefore available in a series of 270 cases for a period extending up to 30 years after the initial operation. There have been 13 histologically verified recurrences (4.8%), and a further six cases are known from CT scan or air study evidence to have residual or recurrent tumour which has not necessitated re-exploration. The total recurrence or residual tumour rate could therefore be regarded as 7.4%. The large majority (77%) of recurrences have been within 10 years of the first operation, and the rest between 10 and 20 years. Histologically, all were chromophobe adenomas, and the average age of their initial presentation was lower than the peak incidence of pituitary adenoma as a whole. Two patients showed frank malignant change in the second biopsy. In recurrent tumours, most had had only subtotal excision with some macroscopic evidence of invasion or degeneration, such as cystic change, haemorrhage or necrosis. Microscopic evidence of aggressive growth and capsular invasion by tumour cells also was relatively frequent. Postoperative radiotherapy decreased and delayed recurrence, although the vast majority of cases in the series received radiotherapy. Surgery for recurrence appeared an effective method of treatment, and no patient died following repeated operation. Initial transcranial excision in more recent years using the operating microscope followed by uniform radiotherapy, appears to have considerably reduced the already small recurrence rate of pituitary adenoma.

Adenoma, Chromophobe↗
PubMed1981

Spinal haemangioblastoma associated with syringomyelia and multiple lung lesions.

Haemangioblastomas involving the spinal cord are uncommon but by no means unknown. It is well established that haemangioblastomas of the central nervous system are commonly associated with lesions in the retinae and in various abdominal organs. The simultaneous occurrence of similar tumours in the lung is less common and not well recognized. The case of a man with a haemangioblastoma of the spinal cord with many small haemangioblastomas of the lung is reported here.

Hemangiosarcoma↗
PubMed1981

Changes in extracellular calcium activity in cerebral ischaemia.

Changes in extracellular ion activities were measured during partial ischaemia of the cerebral cortex of primates anaesthetized with alpha-chloralose. Triple-barrelled, double-ion-sensitive microelectrodes were used to measure the extracellular potassium (Kc) and calcium (Cac) activity at the same point simultaneously. The ion changes were related to local cerebral blood flow, and it was shown that at a blood flow of approximately 10 ml 100 g-1 min-1, there is a threshold below which ion homeostasis is disturbed. This is associated with a dramatic rise in Ke and fall in Cae. Cae falls from a normal value of 1.31 +/- 0.1 mM to approximately 0.28 mM in densely ischaemic tissue. In ischaemia, Ke reaches 13.4 +/- 3.8 mM before Cae begins to fall. The fall in Cae, although related to reduced blood flow, is closely associated with and follows the rise in Ke. The change in Cae is probably due to an increase in membrane permeability, as a result of either depolarisation or a critical lowering of cellular energy reserves.

Animals↗
PubMed1981

Clinical features, investigation and treatment of post-traumatic syringomyelia.

Thirteen patients who sustained spinal cord trauma causing persisting disability, developed new symptoms, the chief one of which was severe pain unrelieved by analgesics. The clinical diagnosis of post traumatic syringomyelia was confirmed in each case by means of myelography, as well as endomyelography in seven patients. In every case exploration of the spinal cord syrinx was performed. Ten patients were troubled by severe pain while three patients were mainly subject to altered sensation in the upper limbs. Of the six patients who had initially sustained complete cord transections, three were treated by cord transection and three were treated by syringostomy. The seven patients who sustained incomplete cord lesions were all treated by syringostomy. The patients who initially sustained incomplete sensory motor spinal cord damage had a better symptomatic response to surgery than hose who had sustained a complete spinal cord lesion. The ten patients whose main symptom was severe pain were completely relieved of their symptoms by surgery.

Adult↗
PubMed1981

Aspergillus granuloma of the trigeminal ganglion.

A patient is described with aspergillus flavus granuloma of the trigeminal ganglion. The patient was effectively treated by surgical excision of most of the infected tissue followed by intensive chemotherapy with amphotericin B and flucytosine.

Adult↗
PubMed1980

Effect of high haematocrit on alertness.

Patients with high-normal or above-normal haematocrit were found to have impaired alertness when compared with a control group matched for age and occupation. On retesting the controls had improved alertness scores attributable to a practice effect; but the patients, when retested after reduction of haematocrit by venesection, had improved significantly more than the controls. Improvement in alertness correlated very well with the increase in cerebral blood flow which followed venesection. Levels of venous haematocrit that are generally accepted as normal may not necessarily be optimum.

Adult↗
PubMed1980

Primary plasmocytomas of the cranial vault.

Primary intracranial plasmocytomas are rare in neurosurgical practice. The accessible literature indicates that they fall into two groups: 1. Extramedullary plasmocytoma originating from the dura and 2. Plasmocytoma originating from the cranial vault. Four patients with primary lesions of the cranial vault were surgically treated and common characteristic clinical and radiological features discussed. Although the immediate outcome of treatment was excellent in all cases, the dissemination of disease occurred in two patients within the period of one year. It is therefore essential that the patients with so called solitary cranial plasmacytoma were rescreened for systemic myelomatosis at regular intervals.

Cerebral Angiography↗
PubMed1980

Viscosity, cerebral blood flow and haematocrit in patients with paraproteinaemia.

It has been suggested that blood viscosity is involved in the control of cerebral blood flow (CBF) (Thomas et al. 1977a, b, Humphrey et al. 1979). CBF, using the intravenous Xenon133 technique, blood viscosity and haematocrit were measured in 21 patients with elevated viscosity due to paraproteinaemia and found to be the same as in normal subjects. However, the paraproteinaemic patients were anaemic with a mean haematocrit of 0.342. This degree of anaemia would normally be associated with a high CBF. The paraproteinaemic patients were then compared with a group of 10 anaemic patients with matched haematocrits but without paraprotein bands. The whole blood and plasma viscosities were significantly higher in the paraproteinaemic patients and the CBF was significantly lower. The haematocrit, and therefore oxygen carriage, was similar in the two groups. It is likely that in the anaemia of paraproteinaemia the expected increase in CBF did not occur because of the limiting factor of increased viscosity. This suggests that in this instance viscosity rather than oxygen carriage is a major determinant in the control of CBF. This is further emphasized by the better correlation between CBF and blood viscosity than between CBF and haematocrit. It seems likely that viscosity and oxygen carriage are independent variables in the control of CBF.

Aged↗
PubMed1980

Cerebral blood flow, haematocrit and viscosity in subjects with a high oxygen affinity haemoglobin variant.

The cerebral blood flow is low in primary polycythaemia, and it has been suggested that this is due to the increase in viscosity which accompanies the elevated haematocrit. In the present study cerebral blood flow has been measured by a non-invasive 133Xenon technique in six subjects with an elevated haematocrit secondary to a haemoglobin variant with increased oxygen affinity. Flow was significantly higher than normal and 81% higher than in 11 subjects of comparable age, matched for haematocrit and viscosity, but without the haemoglobin variant. In patients with this unusual type of polycythaemia, cerebral blood flow is high despite the elevated blood viscosity and the implications of these results are discussed.

Adult↗
PubMed1980

Cerebral blood flow after surgery for recent subarachnoid haemorrhage.

243 measurements of cerebral blood flow by a noninvasive (133)Xe clearance technique have been made in 45 patients undergoing surgery for a recently ruptured cerebral aneurysm. Two groups of patients have been defined by the presence or absence of a postoperative rise in cerebral blood flow which showed a significant correlation with level of consciousness after operation.

Adolescent↗
PubMed1980

Computed tomography in aneurysmal subarachnoid haemorrhage.

The initial CT scans of 76 patients with aneurysmal subarachnoid haemorrhage were reviewed, and the amount of blood visible in the basal CSF cisterns was quantified. The outcome of surgery was found to correlate significantly with the quantity of blood seen on the scan, as did the pre-operative grade of the patient, a history of pre-existing hypertension, and the presence of angiographic vasospasm.

Adolescent↗