Education And Debate

For Debate: Reflex responses do not necessarily signify pain

BMJ 1996; 313 doi: https://doi.org/10.1136/bmj.313.7060.797 (Published 28 September 1996) Cite this as: BMJ 1996;313:797
  1. Adrian R Lloyd-Thomas, consultant in paediatric anaesthesia and pain managementa,
  2. Maria Fitzgerald, professorb
  1. a Department of Anaesthesia, Great Ormond Street Hospital for Children NHS Trust, London WC1N 3JH
  2. b Department of Anatomy and Developmental Biology, University College London, London WC1E 6BT
  1. Correspondence to: Dr Lloyd-Thomas.

    Can a fetus feel pain? This question is appropriate, as medical interventions during pregnancy,1 fetal surgery,2 and possibly termination of pregnancy expose the fetus to noxious stimuli. To answer the question we need definitions of “feeling” and “pain.” The International Association for the Study of Pain defines pain as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage” and goes on to emphasise the importance of experience related to past injury. To feel something is defined as “to have the emotions excited, to experience a sensation.” These definitions imply that the brain must achieve a certain level of neural functioning, as well as having prior experience, before pain can be understood.

    Neural maturation of any brain region includes so many stages and events that it is inadequate to use the presence or absence of any one event as evidence of functioning, but a critical factor must be the arrival of thalamocortical connections. These first penetrate the frontal cortical plate at 22-34 weeks,3 and their arrival correlates well with evoked potential studies, which show that the distinct component signalling the arrival of sensory impulses at a cortical level cannot be detected before 29 weeks.4

    Role of sensory processing at lower levels

    But is it appropriate in …

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