Central nervous pathways mediating angina pectoris

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Central nervous pathways mediating angina pectoris.

Rosen SD, Paulesu E, Frith CD, Frackowiak RSJ, Davies GJ, Jones T, Camici PG (1994)

Lancet. 344: 147-50

This paper has considerable potential importance for acupuncture. It describes a study of changes in brain flow in patients with angina.

Angina pectoris is an example of visceral pain, and we know that visceral pain stimuli are transmitted through sympathetic afferents and thence ultimately to the posterior thalamus, but what happens next is uncertain. Light has now been shed on the question by this study at the Hammersmith Hospital. Pain was precipitated by dobutamine infusion, and blood flow changes were measured with positron emission tomography.

A number of areas showing increased activity during angina were identified. An important finding was that thalamic but not frontal cortical activity persisted throughout the post-angina scan. This indicates that the thalamus continues to receive input from the heart after angina ceases to be felt, but the less intense signal does not reach the cortex and consequently there is no conscious perception of angina. Possibly the same mechanism explains silent myocardial ischaemia. There are important differences between these findings and those for somatic pain. Other kinds of visceral pain could be transmitted in the same way as angina.

Although this study may seem rather remote from clinical practice, it may have relevance to the use of acupuncture to treat visceral pain, including angina. Is it possible, for example, that acupuncture blocks the transmission of signals from the thalamus to the cortex? If so, it would provide a simple explanation for the apparent clinical effectiveness of acupuncture in visceral pain. Presumably it would be a fairly simple matter to test this hypotheses experimentally. If confirmed it would emphasise the desirability of acupuncture being practised under the direct supervision of doctors, since the decision whether or not to treat angina would require fine clinical judgement.

The British Medical Acupuncture Society.

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By Anthony Campbell

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