496 



HANDBOOK OF PHYSIOLOGY 



NEUROPHYSIOLOGY I 



Remtton to Pain 



The complexities of the cerebral mechanisms re- 

 sponsible finalK for normal appreciation of and reac- 

 tion to pain are at present lara;ely beyond our 

 knowledge. 



Using the radiant heat method of Hardy et ai 

 (115), Chapman (39) studied thresholds to 'pain 

 perception,' i.e. the subjective end point signalled by 

 the patient; and to 'pain reaction,' the first objective 

 evidence of withdrawal, such as wincing, seen by the 

 examiner. He found that a group of psychoneurotic 

 patients, while presenting abnormal pain perception, 

 showed an abnormally low threshold for pain reaction. 



INDIFFERENCE TO p.AiN. The Contrary state, indif- 

 ference to pain, has been seen temporarily in periods 

 of severe emotional stress or in hypnosis, or over longer 

 periods of time in hysteria, psychosis and posten- 

 cephalitic states, and in mental defectives. In the 

 latter two groups no eflTort has been made to correlate 

 any particular lesions of the brain with this s\ mptom. 

 An extraordinary and rare phenomenon, described 

 as 'a congenital insensiti\ity to pain' of many types, 

 may occur in people otherwise apparently nearly 

 normal. A detailed perusal of the case reports is re- 

 quired to appreciate the severity and \ariety of the 

 injuries and noxious stimuli which such indi\iduals 

 have repeatedly sustained without pain (32, 51, 59, 

 81, 136, 148, 224, 236). Seven other case reports 

 are cited by Madonick (182), although his own case, 

 I think, belongs in the mental defective group men- 

 tioned above. A feature common to nearlv all of these 

 indi\iduals has been their ability to distinguish with 

 fair or great accuracy between the point and head of 

 a pin or between slight differences of temperature. 

 Yet they are indifferent to violent jaijs and extremes 

 of temperature and their utter lack of suffering is 

 their striking characteristic. Boyd & Nie's (32) phrase 

 "congenital universal indifference to pain" more 

 clearly indicates the person's beha\ior and that 

 the abnormality is central rather than peripheral. A 

 number of them do experience discomfort upon cu- 

 taneous electrical stimulation at high levels, morbid 

 distension of viscera, or other extreme noxa. The 

 brain of no such person has yet been studied histo- 

 logically, but the occurrence of various types of 

 seizures or minor mental defect in several of them 

 intimate that an organic lesion is present. 



PAIN ASYMBOLIA. A State with slight similarity to the 

 foregoing has been described by Schilder & Stengel 



(239) as 'pain asymbolia,' the situation in which there 

 is "no analgesia in the common sen.se, but the psvchic 

 reaction to the sensation is absent." They (240) have 

 observed this symptom in 10 patients with acquired 

 organic cerebral disease and ha\e implicated the 

 anterior part of the lower part of the dominant 

 parietal lobe. Autopsies on three of the patients 

 showed \'arious lesions of which the\- thought the 

 common denominator was involvement of the supra- 

 marginal gyrus. However in these patients there was 

 a concomitant sensory aphasia which made appraisal 

 difficult, and at least in soine of them there was a 

 "dulling of the appreciation of pain" as well as an 

 insufficient pain reaction. Moreover this dullness ex- 

 tended to a lack of concern over threatening gestures 

 made toward the patient, intimating a general dis- 

 turbance of the capacity to appreciate danger. 



Rubins & Friedman (230) have contrif)uted four 

 more patients in whom this general clinical picture 

 was present and in two of whom operati\e findings 

 placed the lesion mainly in the dominant inferior 

 parietal region. Although these patients recognized 

 a pin as sharp, they did not withdraw from either 

 painful stimuli or threatening gestures. But thev also 

 showed mild perceptive and more se\ere amnestic 

 aphasia, right-left disorientation, inaljility to repro- 

 duce postural attitudes in space, Gerstmann's svn- 

 dromc and idiokinetic apraxia. Hence, the 'asymbolia 

 for pain' is b\- no means the isolated phenomenon 

 seen in the syndrome of congenital indifference 

 to pain. Hecaen & de Ajuriaguerra ('''3). adding a 

 case report, note that in a number of other recorded 

 patients as well as theirs the lesion extended into the 

 posterior inferior part of the frontal lobe. 



.\n e\-en greater variety of locus of lesion was seen 

 by VVeinstein et al. (290) in 15 patients with pain 

 asymbolia who did not have any aphasia. Such a 

 group was .selected for a special study of personalit\-, 

 and many of the patients had lesions in the non- 

 dominant hemisphere. Their heedlessness of noxious 

 stimulation was often accompanied b\ inattention to 

 disabled parts, by muteness, by hypokinesia or by 

 depression. The authors considered all of these symp- 

 toms as to some extent an implicit denial of illness, 

 perhaps related to actual \erbal denial of illness or 

 anosognosia. They considered such behavior related 

 more to the personality background of the patient 

 than to any specific lesion in the brain, and thought 

 the premorbid personality of patients with 'pain 

 asymbolia' was characterized by the habitual use of 

 withdrawal and axoidance in stressful situations. It 

 is apparent that the attribution of a depres.sed reac- 



