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Biomedical subjects

J W Lance

Publications and source records attributed to J W Lance.

At least 109 records · Page 6Linked to original sources
PubMed1981

Extracranial vascular reactivity in migraine and tension headache.

The amplitude of temporal artery pulsation was monitored at rest, after standing from the sitting position and after exercise in 23 normal controls, 10 patients subject to chronic tension headache and 107 migrainous patients. The pulses of migrainous patients did not differ from normal at rest or on standing. On exercise, the temporal artery on the habitually affected side of migrainous patients dilated more than the headache-free-side, while exercise-induced changes in tension headache patients were less than those in normal controls. The responses were not influenced by previous or current medication.

Adult↗
PubMed1981

Disordered muscle tone and movement.

The author's interest in the motor system is traced over a period of 30 years. Early studies on the cat pyramidal tract proved to be of relevance to later work on the control of muscle tone by brain stem and cortical mechanisms. Application of physiological methods disclosed fundamental differences between the increased tone of Parkinson's disease, spasticity and decerebrate rigidity. These differences depend upon the extent to which dynamic and static stretch reflexes are released, and whether the control effects of flexor reflex afferents remain under the control of the brain stem (as in Parkinson's disease), are released (as in spasticity) or even reversed (as in decerebrate rigidity).

Animals↗
PubMed1980

Effects of low doses of clonidine in the monkey cranial circulation.

Migraine therapy using low doses of clonidine has been based on the proposal that clonidine directly inhibits vascular smooth muscle reactivity. In anaesthetized monkeys in which internal and external carotid vascular resistances were measured, the only significant effects of clonidine administered acutely (0.5 and 2 microgram x kg-1 i.v.) or chronically (2 microgram x kg-1 i.m. daily for 7 days) on cranial vascular responses to the constrictors noradrenaline and 5-hydroxytryptamine, and the dilators histamine, prostaglandin E1 and bradykinin, were small potentiations of some of the responses. Acute clonidine initially increased blood pressure and constricted the cranial vasculature, then induced hypotension without involvement of the cranial circulation. It also decreased the external carotid vasoconstrictor response to low frequency cervical sympathetic nerve stimulation. The low chronic dose of clonidine had no hypotensive effect. The pressor response to common carotid occlusion was inhibited by both acute and chronic clonidine. These experiments thus provide no evidence that clonidine inhibits cranial vascular reactivity at doses equivalent to those used in migraine.

Animals↗
PubMed1980

Neck-tongue syndrome on sudden turning of the head.

A syndrome of unilateral upper nuchal or occipital pain, with or without numbness in these areas, accompanied by simultaneous ipsilateral numbness of the tongue is explicable by compression of the second cervical root in the atlantoaxial space on sharp rotation of the neck. Afferents fibres from the lingual nerve travelling via the hypoglossal nerve to the second cervical root provide a plausible anatomical explanation for compression of that root causing numbness of half the tongue.

Adolescent↗
PubMed1979

Hyperexcitability of motor and sensory neurons in neuromyotonia.

Two members of a family with a neuropathy resembling Charcot-Marie-Tooth disease were unable to relax their muscles after voluntary contraction. Muscle spasm often outlasted voluntary contraction by 30 seconds or more before subsiding into myokymia and fasciculations. The posture of the hand during muscle spasm resembled that of tetany, and Trousseau's and Chvostek's signs were present although no abnormality of calcium or magnesium metabolism could be demonstrated. Muscle spasms ceased during medication with carbamazepine, 600 mg daily. Nerve stimulation, electromyography, and regional neuromuscular blockade with curare indicated that the condition originated in peripheral nerve, while microneurographic recordings showed that sensory as well as motor fibers were hyperexcitable. Sural nerve biopsy revealed axonal degeneration involving myelinated and unmyelinated fibers. It was concluded that the neural hyperexcitability is caused by a membrane defect resulting in a low threshold for excitation throughout the length of the axon.

Adult↗
PubMed1979

Neuromyotonia in the spinal form of Charcot-Marie-Tooth disease.

The term neuromyotonia has been applied to spontaneous activity of peripheral motor nerves which gives rise to pseudomyotonia, muscular fasciculations and myokymia. A family is described in which 8 members of 3 generations suffer from the spinal form of Charcto-Marie-Tooth disease (distal type of chronic spinal atrophy). 5 of the 8 members were examined and found to have myokymia, accentuated by voluntary muscle contraction. Pseudomyotonia was present in 2 patients and, in the 1 patient treated, was abolished by carbamazepine. The association between neuromyotonia and charcto-Marie-Tooth disease has been reported in only 7 patients before but may be more common than previously thought because muscle cramps are reported to be a feature of this disorder.

Adult↗
PubMed1978

A double-blind trial of bromocriptine in Parkinson's disease.

Twenty-two patients entered a double-blind trial to test the efficacy of bromocriptine therapy in patients with Parkinson's disease who were already stabilized on conventional L-Dopa therapy. Of these, three patients who were receiving placebo withdrew when no improvement occurred and control became complicated. Another four patients taking active drug withdrew because of side effects, but only in one case was the symptom (nausea and vomiting) thought to be a true effect of the drug. Of the 15 patients who completed the trial, nine were taking active drug and six took placebo. Although more than half the patients in each group were subjectively improved, measurement scales of functional disability and physical examination revealed no significant change in either group. Side effects encountered included nausea, dyskinesia, and hallucinations. It was concluded that bromocriptine does not offer any additional benefit to patients with Parkinson's disease who are stabilized on L-Dopa therapy, but may have a place in those patients who encounter side effects due to fluctuations in serum and tissue levels of L-Dopa.

Bromocriptine↗
PubMed1978

Effects of methysergide, pizotifen and ergotamine in the monkey cranial circulation.

Internal and external carotid vascular resistances were measured, in anaesthetized monkeys, to asses the direct cranial vascular effects of i.v. methysergide, pizotifen and ergotamine, and their effects on the cranial vascular responses to the constrictors 5-hydroxytryptamine and noradrenaline and the dilators histamine, prostaglandin E1 and bradykinin. Methysergide reduced responses to 5-HT, and tended to potentiate the external carotid responses to noradrenaline. Pizotifen blocked responses to histamine; it tended to reduce internal carotid responses to 5-HT, but it potentiated external carotid 5-HT responses. Ergotamine reduced responses to 5-HT and noradrenaline, but this was probably related to its cranial vasoconstrictor effects, especially in the external carotid circulation. Methysergide induced weak transient cranial vasoconstriction and pizotifen had no direct effects. These findings may be relevant to the therapeutic actions of these drugs in migraine, since the doses used approximated to those used clinically.

Animals↗
PubMed1978

Internal and external carotid vascular responses to vasoactive agents in the monkey.

Internal and external carotid blood flows in anesthetized monkeys were measured simultaneously using electromagnetic flowmeters. Complete dose-response relationships were established for the effects of intracarotid infusion of several humoral agents implicated in migraine. Both the internal and external carotid vasculatures were constricted by serotonin and prostaglandin F2alpha and dilated by bradykinin, histamine, and acetylcholine. Noradrenalin and adrenaline constricted the external carotid vasculature but had little direct effect in the internal carotid territory. Prostaglandin E1 dilated the external carotid vasculature. Low doses of prostaglandin E1 produced dilation in the internal carotid circulation, but with higher doses there was a paradoxical abolition of this effect.

Acetylcholine↗
PubMed1978

A physiological approach to motor disorders.

Spasticity in man is presented as a disinhibition of spinal cord mechanisms, the responses to stretch depending on the interaction of the reflex effects of group Ia with those of group II afferent fibres. The reflex responses to muscle stretch and shortening in Parkinson's disease do not depend on an abnormality of spinal reflex mechanisms. The superimposition of physiological tremor or alternating tremor in rigidity produces the classical cog-wheel sensation. The phase lead of the action tonic stretch reflex was found to be reduced in patients with athetosis and cerebellar disease, thus diminishing damping of unwanted movements. The more complex transmission characteristics of the action tonic stretch reflex of normal man are absent in patients with spasticity and cerebellar lesions, presumably due to interference with long-loop pathways. In normal subjects gain of the reflex loop increases with voluntary contraction but in spasticity gain remains high irrespective of contraction level.

Athetosis↗
PubMed1978

An evaluation of bromocriptine in the treatment of Parkinson's disease.

22 patients entered a double-blind trial to test the efficacy of bromocriptine therapy in patients with Parkinson's disease already established on conventional levodopa therapy. 3 patients on placebo withdrew when no improvement occurred and control became complicated. 4 patients on active drug withdrew because of various symptoms, but in only 1 case were these (nausea and vomiting) thought to be a real drug effect. Of the 15 patients who completed the trial, 9 were on active drug and 6 were on placebo. Although more than half the patients in each group were subjectively improved, measurement scales of functional disability and physical examination revealed no significant change in either group. Side effects encountered included nausea, dyskinesiae and hallucinations. It is concluded that bromocriptine does not offer any additional benefit in most patients with Parkinson's disease who are well stabilised on levodopa therapy, but may have a place in those patients who encounter side effects due to fluctuations in serum and tissue levels of levodopa.

Aged↗
PubMed1978

Headache.

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Acute Disease↗