Mechanisms of traumatic brain injury.

The authors describe the mechanisms of traumatic brain injury (TBI), examining in depth the characteristics of closed head, penetrating, and blast-related TBI. Events on a structural as well as cellular level are reviewed. Blast-related brain injury, in particular, affects military service members preferentially, but is also relevant in cases of industrial accidents as well as terrorist events.

Symptoms of PTSD Associated With Painful and Nonpainful Vicarious Reactivity Following Amputation.

Although the experience of vicarious sensations when observing another in pain have been described postamputation, the underlying mechanisms are unknown. We investigated whether vicarious sensations are related to posttraumatic stress disorder (PTSD) symptoms and chronic pain. In Study 1, 236 amputees completed questionnaires about phantom limb phenomena and vicarious sensations to both innocuous and painful sensory experiences of others. There was a 10.2% incidence of vicarious sensations, which was significantly more prevalent in amputees reporting PTSD-like experiences, particularly increased arousal and reexperiencing the event that led to amputation (φ = .16). In Study 2, 63 amputees completed the Empathy for Pain Scale and PTSD Checklist-Civilian Version. Cluster analyses revealed 3 groups: 1 group did not experience vicarious pain or PTSD symptoms, and 2 groups were vicarious pain responders, but only 1 had increased PTSD symptoms. Only the latter group showed increased chronic pain severity compared with the nonresponder group (p = .025) with a moderate effect size (r = .35). The findings from both studies implicated an overlap, but also divergence, between PTSD symptoms and vicarious pain reactivity postamputation. Maladaptive mechanisms implicated in severe chronic pain and physical reactivity posttrauma may increase the incidence of vicarious reactivity to the pain of others.

Observation of limb movements reduces phantom limb pain in bilateral amputees.

BACKGROUND: Mirror therapy has been demonstrated to reduce phantom limb pain (PLP) experienced by unilateral limb amputees. Research suggests that the visual feedback of observing a limb moving in the mirror is critical for therapeutic efficacy. OBJECTIVE: Since mirror therapy is not an option for bilateral lower limb amputees, the purpose of this study was to determine if direct observation of another person's limbs could be used to relieve PLP. METHODS: We randomly assigned 20 bilateral lower limb amputees with PLP to visual observation (n = 11) or mental visualization (n = 9) treatment. Treatment consisted of seven discrete movements which were mimicked by the amputee's phantom limbs moving while visually observing the experimenter's limbs moving, or closing the eyes while visualizing and attempting the movements with their phantom limbs, respectively. Participants performed movements for 20 min daily for 1 month. Response to therapy was measured using a 100-mm visual analog scale (VAS) and the McGill Short-Form Pain Questionnaire (SF-MPQ). RESULTS: Direct visual observation significantly reduced PLP in both legs (P < 0.05). Amputees assigned to the mental visualization condition did not show a significant reduction in PLP. INTERPRETATION: Direct visual observation therapy is an inexpensive and effective treatment for PLP that is accessible to bilateral lower limb amputees.