PubMed1995
The preceding describes some of the confusion which abounds in practically all areas of clinical medicine and particularly in occupational injuries. In essence, this confusion devolves to a primary failure on our part as clinicians; the failure to differentiate fact from fantasy. In the clinical arena, this is the failure to differentiate between that which is clinical pathology in the peripheral neuromusculoskeletal system and that which is no less real for the patient, a fantasy arising from image-driven, adaptively-initiated activation of specific neuronal groups in the somatosensory or somatomotor cortex, descriptively referred to as "hysterical" or "psychogenic." A common experience of neurologists and other clinicians conducting a sensory examination of the extremities is the presence of nondermatomal or glovelike sensory changes of the feet or hands. Nondermatomal sensory changes are known to engage any part of the body surface. These have often been referred to as hysterical; however, in the clinical sensory examination for touch, vibration, and pinprick, the patient has no control over the area or boundaries of the activated receptive fields in the somatosensory cortex. Fantasies of the patient, provoked by the context of examination, initiate an adaptive response which can expand or contract the boundaries of the somatosensory receptive fields. These sensory changes are unconscious and represent alteration of receptive fields in the somatosensory cortex. The brain is re-entrantly connected. Activation in one area promotes activation in adjacent and associated areas remote from the primary receptive field. The brain organizes its own activity. "Perception thus is not imposed on the brain; rather the brain selects the perceptual mode.... stimulus energy, according to numerous studies from brain-activation, is only a weak determinant of the magnitude of response in primary sensory areas. . . ." The most intense brain activation in the somatosensory cortex is provoked, not by peripheral stimulation, but by adaptive preparation referred to as somatotopical tuning, probably due to an increase in excitatory post-synaptic potentials (EPSPs). Many patients present to neurologists and other clinicians with complaints of numbness and tingling in the fingers, hands, arms, or face and occasionally, as in one of my patients, the entire body.(ABSTRACT TRUNCATED AT 400 WORDS)