Imagined movements in spinal cord injury pain patients improves pain and restores cortical activation patterns to normal

A recent study (reported at IASP 2010 in Montreal) enrolled 13 patients with pain below the level of spinal cord injury into a 6-week training program employing 30 mins of imagined movements and sensation in painful limbs every day. Participants kept daily pain diaries and functional MRI (fMRI) scanning was performed both before and after the training program. Healthy controls were also scanned at baseline for comparison purposes.

The fMRI scan below shows activity in normal subjects in response to executed movement of the right hand. Activity is primarily in the primary motor and somatosensory cortices and supplementary motor area.

This next image shows brain activity in response to the same movement in spinal cord injury patients before imagery training. Notice that activity in motor circuits is considerably lower compared to normals.

This final image shows brain activity in the same spinal cord injury patients after the 6-wk mental imagery program. The activation maps look very similar to the healthy controls, with activity in the motor pathways.

Imagining pain can make it so

Perhaps one of the ways in which chronic pain reinforces itself is because people are exposed to the pain either constantly or repeatedly (in the case of recurring pain conditions) and so become exceedingly familiar with how it feels. This familiarity can fuel more complete and vivid imagining of the pain experience, which may very well exacerbate the pain. Indeed, it may very well that it is not fear per se that is the problem when people anticipate pain, but rather than they are imagining what the pain will feel like and it is the mental “picture” of the pain in advance of any actual pain, which evokes fear.

Evidence now exists that simply imagining pain can actually activate much of the same pain circuits in the brain that are typically involved during the experiencing of painful stimuli.

Allodynia is a condition in which normally innocuous or even pleasurable tactile sensations are perceived as painful. Kramer et al (2008) showed that by imagining touch as painful (imagined allodynia) activates the same neural structures as actual allodynia. They divided healthy participants into two groups. The first group had previously been exposed to experimentally induced allodynia within the past 6 months. The second group had no experience with allodynia and so did not know what touch-evoked pain is like. Both groups received tactile stimulation on hand and then the other, but they were asked to imagine that the sensation on the right hand was painful. Non-painful tactile stimulation activated contralateral S1 and S2 (see top panel of figure below). During imagination of allodynic pain in the right hand, there was activation in the ACC and Insula and medial frontal cortex in addition to contralateral S1 and bilateral S2 (see lower panel of figure below).

Thus, people who have had prior experience with allodynia are able to conjure up the experience in their imaginations and when they do, the brain regions normally associated with painful touch sensations become activated. Those with more allodynia experience showed more pronounced activation in the contralateral S1, mid insula, inferior frontal cortices, ACC and ipsilateral amygdala (see figure below):

Preamputation Mirror Therapy May Prevent Development of Phantom Limb Pain

Mirror therapy has been effectively employed to treat majority of the 72 % of amputees with  phantom limb syndrome, suffering from  both  non-painful and painful sensations. Mirror therapy involves patients placing their intact limb into one side of a box divided by a mirror. This mirror is placed in a way that when viewed slightly off center, allows patients to perceive themselves as having 2 intact limbs. Having this perception, patients perform a series of movement exercises with the intact arm. Then, as unscientific as it may sound, the pain vanishes. The question remained that,  if mirror therapy can treat phantom limb pain, couldn’t it be used to prevent it from occurring before hand? They conducted a 4 case study involving 4 male patients in their early to late twenties who  had previously experienced various traumatic injuries that rendered their limbs inoperative. To test this connection in possibly preventing  phantom limb pain, all patients underwent 14 sessions of mirror therapy before their amputations. The follow ups of 1 month after each patient’s surgery revealed moderate to no phantom limb pain. Those who experienced moderate phantom limb pain expressed that they were tolerable and did not hamper their quality of life. Noticing the varied outcomes, the researchers reflected that the length of the mirror therapy sessions should be prolonged according to patients and their conditions. The mechanism behind the effects of mirror therapy on phantom limb pain is  still a mystery in the field of psychology. However, with up coming studies, even a small contribution of knowledge in the ability to prevent phantom limb pain can have a dramatic impact on the public, the amputees themselves, and future research.

Hanling, Steven R. MD; Wallace, Scott C. MD; Hollenbeck, Kerry J. MD; Belnap, Brian D. DO; Tulis, Matthew R. MD. Anesthesia & Analgesia (February 2010), 110(2),pg 611-614

Illusory walking eases phantom pain in paraplegics

Pain after spinal cord injury occurs in about 65% of cases and many of these report that it is this pain, rather than paralysis that prevents them from functioning at work and other activities (Moseley, 2007). Moseley (2007) had 5 paraplegic men sit in front of a vertical screen with legs hidden by a horizontal board (see Figure below).

Participants experience three 10-min conditions undertaken on separate days. In the first,  virtual walking, a video of an actor walking is projected onto the vertical screen. A mirror placed at the top of the screen reflects an image of the top part of the participant’s body. Patients were instructed to move their upper body so that it is synchronized to the walking legs seen on the bottom of the screen. As seen in the figure above, this setup creates the illusion that the participant is walking. To control for distraction, participants also engaged in a guided imagery condition, and were lead through a scenario in which they performing pleasurable activities and were pain free. In the comedy film condition, participants simply watched an animated comedy film. Pain intensity was reported every 30 seconds from prior to and throughout each condition (except the guided imagery condition).

Moseley (2007) found that during virtual walking pain decreased by about 65% from the period 3 mins before the exercise. Pain decreased by about 30% in the guided imagery condition and less than 10% while watching the comedy film. It also took substantially longer for patients to return to pre-activity pain after virtual walking (35 mins) compared to 14 mins after guided imagery and 16 mins after the film. They also perceived decreased foreignness, and less heaviness during virtual walking.

For more info:

Moseley, L. (2007). Using visual illusion to reduce at-level neuropathic pain in paraplegia. Pain, vol. 130 (3) pp. 294-298

The magical mirror: How a simple mirror can rewire the brain and ease pain

Phantom limb pain (PLP) is a common sequela to amputation. The majority of amputees report pain, often very severe, which seems to emanate from the missing limb. A growing body of evidence suggests that PLP is associated with maladaptive neuroplastic changes in the sensorimotor cortices. When cortical tissue that used to represent the missing limb ceases receiving input from that limb, the tissue from neighboring cortical areas, which represent other body regions, migrate into the area that previously represented the missing limb. Since the face is represented in cortical areas adjacent to the hands and arms, cortical representation of the face migrates into the area that previously represented the amputated limb.

But why should this cortical reorganization lead to pain? One leading hypothesis is that with deaffertation there is a mismatch between motor output and sensory input. The brain sends signals out to the muscles but does not receive the expected feedback. There is a mismatch between motor output and sensory feedback.

What would seem to be needed, then, is some way by which alternative feedback could be presented to convince the brain that he or she can control the limb and that it is responding normally. The problem, of course, is that the patient has no limb to move. That’s where the mirror box comes in.

The mirror box has two parallel compartments with a vertical barrier between the compartments. A mirror surface lines one side of the vertical barrier. The PLP patient places the intact hand on the reflective side of the mirror such that viewing the intact hand in the mirror lends the impression that the missing limb has been “resurrected”.

Ramachandran and Rogers-Ramachandran (1996) reported that most of the 10 patients reported that they could actually feel movements in the phantom limb, which gave them the impression that they could actually change the position of their phantom limb, and hence ease spasms and cramping pain.

Arm crossing in achievement contexts increases persistence and cognitive performance

Researchers at the University of Rochester asked college undergraduates to complete a series of anagrams (rearranging letters to make words). Some participants did so while keeping their arms were crossed the majority of the time, uncrossing them only to type their answers at the computer keyboard, and other participants did so while  keeping their arms down by their thighs. Following the task they rated their mood as well as the degree to which they felt tense/relaxed. They found that participants in the arms-crossed condition continued working on the anagram task longer than did those in the arms-on-thigh condition. Not only that, participants with crossed arms also performed significantly better, coming up with a greater number of correct solutions than those who kept their arms by their thighs.

While previous research had shown that proprioceptive cues can influence affect, attitudes, evaluations and cognitive processing, this study was the first to demonstrate that proprioceptive cues can influence actual behaviors. Specifically, they found that within an achievement context, arm-crossing can lead to considerably enhanced persistence and performance at a cognitive task.

Friedman, R., & Elliot, A. J. (2008). The effect of arm crossing on persistence and performance. European Journal of Social Psychology, 38(3).

Image: photostock / FreeDigitalPhotos.net

Reclining alters the way our brains respond to anger

More than a dozen studies employing electroencephalography (EEG) and repetitive transcranial magnetic stimulation (rTMS) methods have found that the left prefrontal cortex is activated to a greater degree than the right prefrontal cortex during the experience anger, especially when the anger was accompanied by approach inclinations. By contrast, several fMRI studies failed to corroborate these findings. Curious about these divergent findings, Eddie Harmon-Jones and Carly Peterson at Texas A & M university cleverly noted that EEG and rTMS studies are done with the participant in the upright position whereas fMRI studies are performed with participants lying down. They hypothesized that activity in the left prefrontal cortex reflects not just anger but the approach orientation associated with anger and that approach motivations may be diminished while laying down and this might account for the absence of heightened activity in the left prefrontal cortex in the fMRI studies.

To test this hypothesis, they asked college undergrads to spend 10 mins writing an essay supporting their position on a topic such as smoking in public and that these essays would then be evaluated by another participant. They were hooked up to EEG sensors and some were reclined while others remained upright. Then the experimenter took the essay into an adjacent room where the participants essay would supposedly be evaluated by another participant. All reclined overheard negative comments about their essay and personality while half of the participants in the upright condition heard mildly positive comments. Immediately following the feedback, 2 mins of EEG were recorded.

The researchers indeed found that the insult-upright condition produced greater relative left frontal activity than the insult-reclined condition.

It is important to note that body position had no impact on self-reports of anger.  Insults make people feel anger whether reclined or upright but the response of the brain and the impact on our body appears to be quite different. It would be very interesting indeed if future studies measured physiological indicators and compared these between participants in supine or upright positions. Perhaps insulted people in the reclined position feel anger but don’t suffer the deleterious effects of hostility to the same extent as insulted people in an upright, ready-to-fight posture.

Harmon-Jones, E., & Peterson, C. K. (2009). Supine body position reduces neural response to anger evocation. Psychol Sci. EPub

Image: Ambro / FreeDigitalPhotos.net