Sensory function after traumatic upper extremity amputation in the human
By: by Judith Patricia Hunter.
Published: 2006
Language: eng
Number of pages: 245
ISBN-13: 9780494158760
Description: Awareness of a phantom limb (PLA) as an integral part of the body is experienced by almost every individual after amputation. This awareness can be accompanied by specific qualities of sensation (PLS) and/or pain (PLP) in the missing limb. The neural mechanisms underlying these phenomena are not known. Previous hypotheses focused on PLP and were primarily based on data obtained in subjects evaluated several years after their amputation. Furthermore, these studies were potentially confounded by age effects and/or coexisting injuries or disease. The present thesis tested the main hypothesis that phantom awareness is a distinct phantom phenomenon reflecting an altered interaction of multiple sensory inputs and does not reflect cutaneous sensory thresholds. Prospective evaluations (interviews, quantitative sensory testing) were conducted in an unselected cohort of otherwise healthy individuals early (&lt;6 months) after unilateral traumatic upper limb amputation. A subset of subjects was followed longitudinally (&sim;two years). Prevalence and longitudinal data indicated that spontaneous PLA (mostly a stiff, flexed phantom hand) is the most common and stable phantom experience, suggesting that these perceptions reflect conscious body awareness. Spontaneous PLP, PLS, stump pain and evoked PLS/PLA were less prevalent and varied individually over the time period examined. Furthermore, despite a common injury, there was no consistent pattern of abnormalities in tactile or thermal sensory function in the stump. Sensory thresholds did not reflect the quality of the subjective phantom limb experience. These data indicate that (1) the relative contribution of specific mechanisms can vary between individuals and over time and, (2) PLS and PLA are not related in any simple way to cutaneous sensory function. Furthermore, a mirror box illusion was used to examine the interaction and effects of vision and sensorimotor inputs on perceived PLA. Real and illusory visual information about limb position that produced subtle changes in congruence of visual, tactile, and sensorimotor information enhanced spontaneous PLA and dampened evoked PLA. In conclusion, PLA reflect an altered interaction of sensory inputs that normally maintain body awareness and not a specific cutaneous sensory deficit. Spontaneous PLA could arise from a mismatch between expected and actual sensory signals concerning body location.
Notes: Source: Dissertation Abstracts International, Volume: 67-07, Section: B, page: 3694.

Thesis (Ph.D.)--University of Toronto, 2006.

Includes bibliographic references.

Electronic version licensed for access by U. of T. users.