AN ANATOMICAL BASIS FOR ALTERATIONS IN QUALITY OF PAIN SENSIBILITY

Abstract

Biopsies were taken, after sensory testing of the areas concerned, from a series of patients with either cutaneous scars or areas of partially denervated skin. In every case where pain of an unpleasant quality could be elicited by means of a needle-prick, the underlying nerve nets and terminals subserving pain were isolated from their neighbors. Conversely, in no case where this isolation was not found microscopically could pain of unpleasant quality be produced. Alterations in the quality of pain sensibility were not correlated with the presence of morphologically abnormal pain endings. Such endings were however, associated with disturbances of the threshold of pain sensibility. Further evidence concerning the association of pain of unpleasant quality with a reduction in the normal peripheral pattern of innervation was obtained from a number of compression expts. on the normal arm. It is considered that this association is a significant one, and that the occurrence of "over- reaction" to painful stimuli in various clinical conditions is caused by a reduction in the normal pattern of impulses presented to consciousness. The suggestions put forward by previous workers have been discussed in the light of this hypothesis.