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Biomedical subjects

G S Venables

Publications and source records attributed to G S Venables.

11 recordsLinked to original sources

The role of magnetic stimulation in the diagnosis of multiple sclerosis.

Magnetic stimulation was used to measure motor conduction time (MCT) between head and neck, and head and lumbar region, as well as amplitude of the motor evoked potential (MEP) in normal subjects and patients with multiple sclerosis (MS). Patients with definite MS had significantly longer MCTs and smaller amplitude MEPs than normal subjects when recording from arm and leg muscles. In a comparison with visual evoked potential (VEP) recordings, head to neck MCTs were abnormal less often than VEPs, and VEPs detected more silent lesions. Recording from leg as well as arm muscles significantly increased the yield of abnormal MCT measurements. The detection of silent lesions in the patients with definite MS was improved, but there was no improvement in the non-definite cases. Amplitude measurements provided very little extra diagnostic information over MCT measurements alone and did not improve the detection of silent lesions. Interside MCT differences yielded extra abnormalities when recording from the arms but not the legs. Interside MCT abnormalities increased the detection of silent lesions in both the definite and non-definite categories. It was concluded that the majority of useful diagnostic information in patients with MS should be obtainable from bilateral MCT (head to neck) measurements, together with estimation of interside MCT differences. However, VEP recording is a better diagnostic test for MS than MEP recording as more silent lesions are detected. This may be because MCT abnormalities tend to reflect the degree of pyramidal disability.

Adult

The role of magnetic stimulation as a quantifier of motor disability in patients with multiple sclerosis.

Magnetic stimulation was used to measure motor conduction time (MCT) between head and neck in a prospective longitudinal study of patients with multiple sclerosis (MS) and normal subjects. MCT measurements showed a high degree of reproducibility in normal subjects and patients with stable MS. In patients with definite MS, there was significant positive correlation between MCT and motor disability. In patients treated with steroids for relapse of MS, there was significant shortening of MCT following treatment in those who clinically improved, but not in those who were clinically unchanged. In a smaller group of patients followed for 3 months, MCT changes tended to mirror the clinical pattern. Magnetic stimulation should prove a useful tool for the quantification of motor disability, and monitoring the response to new treatments in MS.

Adrenal Cortex Hormones

Abnormalities of central motor conduction in Parkinson's disease.

The new technique of magnetic stimulation was used to measure amplitude of the motor evoked potential (MEP) recorded from abductor digiti minimi whilst stimulating at the head, and motor conduction time (MCT) between head and neck. Bilateral studies were made in 12 normal subjects and 56 patients with Parkinson's disease. The amplitudes of the MEPs were significantly larger (P less than 0.05) in the patients (mean 1.6 mV, SD 1.4) compared with the normal subjects (mean 0.9 mV, SE 0.6). MCTs were significantly shorter (P less than 0.001) in patients (mean 8.1 ms, SD 1.3) compared with the normal subjects (mean 9.4 ms, SD 1.2). Although the pathophysiological basis of these changes has not been determined, they provide objective measurements which may be clinically valuable in monitoring therapy.

Central Nervous System

A randomized double-blind controlled trial of naftidrofuryl in acute stroke.

There is evidence to support the use of naftidrofuryl in acute stroke with claims of increased recovery, reduced fatality and reduced bed occupancy in patients treated with either oral or intravenous preparations. One hundred patients presenting with acute hemisphere stroke (less than 72 hours) were randomized to receive either a new oral formulation of naftidrofuryl or placebo on a double-blind basis. Treatment was given for a total of 12 weeks and patients followed for 26 weeks with serial neurological and functional assessments by a single observer. Cumulative fatality and hospital-bed occupancy were determined at each assessment interval. No significant difference was demonstrated in cumulative fatality, hospital-bed occupancy or recovery of motor function in patients treated with either naftidrofuryl or placebo. There is no evidence from this study to support the use of oral naftidrofuryl in acute stroke.

Acute Disease

Recovery of visual fields in acute stroke: homonymous hemianopia associated with adverse prognosis.

In a prospective study of 157 patients (median age 73 years) admitted to hospital within 72 hours of acute cerebral hemisphere stroke, there was clinical evidence of homonymous hemianopia (HH) as assessed by confrontation in 99 (63%). Patients were followed with serial neurological examinations for 28 days. Complete recovery of visual fields occurred in 14 (17%) of the 81 patients with a complete HH on admission and in 13 (72%) of the 18 patients with a partial HH on admission. Cumulative fatality at 28 days was greater in patients with a complete HH (49%), compared with patients with a partial HH (11%). These two patterns of recovery and outcome probably reflect the differing extent of cerebral damage in the two groups.

Acute Disease

Increasing age, diabetes mellitus and recovery from stroke.

In a prospective study of 200 patients with acute stroke, blood glucose and glycated haemoglobin (HbA1) were measured within 72 hours of onset. Unrecognized hyperglycaemia as defined by a raised stable HbA1 more than two s.d. above the mean reference value and no previous history of diabetes was present in 27%. No correlation existed between patient age and admission blood glucose or HbA1 levels (r = 0.1). Cumulative mortality and recovery of limb function was assessed in the first 136 patients with carotid distribution events. Admission blood glucose greater than or equal to 8 mmol/l was shown to be associated with a significantly greater mortality at 4 and 12 weeks (P less than 0.05). Multivariate analysis with age, glucose, HbA1 as independent variables demonstrated that age was the only significant predictor for death at 4 weeks (P less than 0.05) but at 12 weeks both age and blood glucose were significant (P less than 0.05). In patients less than 65 years blood glucose was a significant predictor for death (P less than 0.05) but in patients less than or equal to 65 years HbA1 and not glucose was significantly (P less than 0.05). Patients greater than or equal to 65 years with HbA1 greater than or equal to 7.5% were significantly more likely to have a raised admission blood glucose. Hyperglycaemia on admission was not shown to influence recovery of limb function. Increasing age is of greatest importance in predicting mortality although blood glucose is of prognostic value especially in the young stroke patient.

Acute Disease

Colonic tuberculosis.

A case of tuberculosis of the colon is described. Attention is drawn to the similarity between this and other inflammatory diseases of the bowel. Colonic tuberculosis is now a rarity even where mycobacterial infection is endemic, and may mimic other inflammatory diseases of the bowel with important consequences for treatment and prognosis. Such a case is now described.

Adult

Hypothyroidism with true myotonia.

A patient with subclinical hypothyroidism who presented with true myotonia is described. There was no evidence that either he or members of his family had dystrophia myotonica or myotonia congenita. Treatment with thyroxine resolved his symptoms completely.

Adult