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Biomedical subjects

N M Murray

Publications and source records attributed to N M Murray.

67 records · Page 4Linked to original sources
PubMed1984

Plasma exchange and immunosuppressive drug treatment in the Lambert-Eaton myasthenic syndrome.

We undertook serial clinical and electromyographic muscle action potential (MAP) amplitude assessments in nine patients with the Lambert-Eaton myasthenic syndrome (LEMS) over 0.5 to 2.5 years who received plasma exchange (PE; 5 to 15 exchanges over 4 to 19 days) and immunosuppressive drug (IS) treatment (prednisolone 60 to 100 mg on alternate days, azathioprine 2.5 mg/kg for 0.5 to 2.5 years), and who had no signs of carcinoma at entry. Eight patients responded to PE. The peak MAP response occurred 10 to 15 days post-PE, representing a 2.5-fold mean increase and was significant (p less than 0.01). Two of three patients who developed carcinoma responded initially to IS. Three of six noncarcinoma patients developed sustained clinical and MAP remission after 0.5 to 1 year; the three others, of whom two were intolerant of azathioprine, improved. IS and PE may benefit LEMS patients, but caution is required when carcinoma risk is high.

Action Potentials↗
PubMed1983

Chronic asymmetrical spinal muscular atrophy.

The clinical and neurophysiological features of 18 cases of chronic asymmetrical spinal muscular atrophy are described. These were patients presenting with asymmetrical neurogenic atrophy involving one or more limbs who had no evidence of pyramidal tract dysfunction after 3 or more years of symptoms. There were twice as many males as females and the mean age of onset of the disorder was about 32 years. None of the patients had bulbar involvement. The tendon reflexes tended to be depressed. The distribution of muscle weakness in the limbs was very variable, and only slowly progressive. In 5 cases symptoms and signs were confined to the hands and forearms. Motor nerve conduction velocities to wasted muscles were slightly reduced but there was no evidence of generalised neuropathy. A diagnosis of chronic asymmetrical spinal muscular atrophy, as opposed to that of classical motor neurone disease, is favoured by an age of onset under 40 years, an absence of pyramidal signs or bulbar involvement after 3 years or more of symptoms, and depressed or absent tendon reflexes. The 2 conditions appear to be clinically distinct and prognosis is considerably better in chronic asymmetrical spinal muscular atrophy. The aetiology of this condition in unknown; it may be of relevance that 2 patients in this series had close relatives with Werdnig-Hoffmann disease.

Adult↗
PubMed1981

Alterations in the number and affinity of junctional acetylcholine receptors in a myopathy with tubular aggregates. A newly recognized receptor defect.

This paper reports the findings in a 32-year-old man who presented in adult life with a myasthenic syndrome characterized by dysphagia, dysphonia, fluctuating ptosis, episodic diplopia and a variable weakness of the limbs and trunk. Electromyography showed a small decremental response, increased neuromuscular jitter and blocking of some components. Histochemical and electron microscopic studies revealed changes in end-plate morphology and prominent tubular aggregations within the muscle fibres. Radiochemical investigations using di-iodinated 125I-alpha-bungarotoxin demonstrated a reduction in the number of AChR and alterations in receptor affinity which suggested an abnormality of the AChR macromolecule.

Adult↗
PubMed1981

Stimulus-sensitive spinal myoclonus.

Two cases of spinal myoclonus are described; in both patients myoclonus was responsive to stimuli and absent during sleep. The first patient was considered to have viral neuronitis and the condition resolved spontaneously. The second patient had spinal cord ischaemia; there was electro-physiological evidence of abnormal alpha motor neurone activity and histological study of the spinal cord revealed a severe reduction in small and intermediate neurones. This supports the theory that spinal myoclonus may result from abnormal activity of alpha motor neurones released from control by spinal internuncial neurones.

Adult↗
PubMed1981

Treatment with oral 4-aminopyridine in disorders of neuromuscular transmission.

Four patients with Eaton-Lambert syndrome, four patients with congenital myasthenia, and one patient with myasthenia gravis were treated with oral 4-aminopyridine for periods of up to 10 months, doses varying from 40 to 200 mg per day. Clinical and electrophysiologic assessment confirmed the effectiveness of the drug when given alone or in conjunction with anticholinesterases. At therapeutically effective doses, central side effects were frequent and unpredictable. Three patients had a generalized fit and one patient developed a confusional state. Adverse side effects must severely limit the place of 4-aminopyridine in the treatment of patients with these conditions.

Adult↗
PubMedDate not supplied

Congenital myasthenia: further evidence of disease heterogeneity.

The findings in two cases of congenital myasthenia investigated by intercostal muscle biopsy are presented. The first case, a 16-year-old boy, showed reduced miniature endplate potential amplitude and normal 125I-alpha-bungarotoxin binding to postsynaptic acetylcholine receptors. Muscle biopsy and endplate ultrastructure were normal. Tubocurarine affinity, ion channel properties, and passive membrane properties were normal. Limited data showed reduced effectiveness of applied acetylcholine in opening ion channels. The second case was an 18-year-old girl with consanguineous parents. Type 2 muscle fiber atrophy was seen in both limb and intercostal muscle. Intercostal endplates were elongated, although ultrastructure was normal. Negligible postsynaptic alpha-bungarotoxin binding suggested an abnormality of the acetylcholine receptor macromolecule.

Adenosine Triphosphatases↗
PubMedDate not supplied

Central motor conduction studies in motor neurone disease using magnetic brain stimulation.

Central motor conduction (CMC) to abductor digiti minimi (ADM) was evaluated in 22 patients with motor neurone disease (MND) using magnetic stimulation of the motor cortex and electrical stimulation at the C7/T1 interspace. CMC was abnormal in 14 patients; prolonged CMC time and absence of response to brain stimulation were more frequent abnormalities than low amplitude responses without prolonged CMC time. The technique can reveal subclinical upper motor neurone involvement and document central motor pathway dysfunction in MND. The patterns of abnormality are not specific to MND; all may occur in other neurological disorders including multiple sclerosis.

Adult↗
PubMedDate not supplied

F responses and central motor conduction in multiple sclerosis.

Two electrophysiological investigations were used to study 18 patients with multiple sclerosis--F wave characteristics including amplitude, persistence and frequency, which can provide a measure of motoneurone excitability, and magnetic stimulation of the cortex, which enables measurement of conduction along central motor pathways. There was an increase in the mean amplitude and persistence of the F response in patients with abnormal central motor conduction (CMC), although no correlation between the degree of abnormality of CMC and increase in F response amplitude was found. Increase in mean amplitude and persistence of the F response were also found in patients with normal CMC but clinical evidence of a UMN disorder (spasticity and/or weakness); there was no correlation, however, between any single F response characteristic and any particular clinical sign. CMC appears to be the preferred test for detecting subclinical motor lesions in MS: of the patient sides with normal clinical examination, 36% showed abnormal CMC, whereas 23% showed abnormal F responses.

Adult↗
PubMedDate not supplied

Latent cochlear damage in personal stereo users: a study based on click-evoked otoacoustic emissions.

OBJECTIVE: To assess the effects of use of personal stereo systems (PS) on hearing by means of the objective measure of transient-evoked otoacoustic emissions. PARTICIPANTS AND SETTING: People aged between 10 and 59 years who had otoacoustic emissions recorded by the National Acoustic Laboratories between 1989 and 1997 were eligible for inclusion. Recordings from participants with hereditary disorders or any form of aural disease (e.g., otitis media, otosclerosis, fluctuant hearing loss, Meniere's syndrome, or exposure to ototoxic substances) were excluded. METHODS: Transient-evoked otoacoustic emission (TEOAE) records were obtained with a standard 260 repetitions of an 80 dB train of clicks used for recording outer hair cell activity. The measure of otoacoustic emission strength was the Otodynamics ILO88 variable Waverepro%. For each participant, all the key factors relating to their hearing history were assessed from patient referral information or from demographic information obtained in writing at the time of recording either in the form of a detailed questionnaire or verbal assessment. Otoacoustic emission data were analysed according to age, industrial noise exposure and personal stereo use. RESULTS: Usable otoacoustic emission records were obtained from 1724 people (1066 males and 658 females). Otoacoustic emission strength declined with age, and was significantly lower in males than females, lower in people exposed to industrial noise than those not exposed, and significantly lower in users of personal stereo systems than non-users. People with both kinds of noise exposure had values which were significantly lower again, indicating an additive effect. CONCLUSIONS: As only 39 people with PS exposure admitted any hearing problems, decline in otoacoustic emission strength forewarns premature hearing loss in personal stereo users.

Acoustic Stimulation↗