Synaesthetic sensations and pain after amputation
Empathy and similar feelings can cause the feeling of phantom pain. I realize that I cringe and really suffer in situations that were no issue for me before the amputation. I am not bitter or frustrated at all - I physically suffer. I go through a bad time right then and right there. I suffer from seeing an ad with what looks like a prosthetic hand stating 'fake watches are for fake people'. I suffer when I watch the ridiculous amputation scenes in Peter Berg's Sony Pictures movie 'Hancock'. And it gives me a stab, or a jolt, when someone obsessed with ametolatistic paraphilia tells me my stump is to them just like a female breast to others. No offense meant - that physically hurts. I cringe, and I pain.
But I am not the only one.
Milly McKenzie lost her right arm to cancer. Watching a Jaws scene of a bloodied hand on a beach sent shocks of pain through the empty space where Milly McKenzie's right arm used to be.
Seeing the raw violence in Texas Chainsaw Massacre felt like a red hot poker being thrust into the hand and forearm she lost to cancer 28 years ago. Her phantom limb pain, a curious condition that affects as many as nine in 10 amputees, can be triggered by the cold or heat making her feel as if her lost limb is swelling in pain or is so bitterly cold she sticks her stump near a heater for relief.
But Victorian scientists have discovered phantom pain can also be triggered by watching or imagining pain in another either in real life or on screen. Australia's largest study of about 300 upper and lower-limb amputees, by Monash University with the Caulfield General Medical Centre, has found some amputees actually feel others' pain, rather than simple empathy.
Melita Giummarra, from the university's school of psychology, psychiatry and psychological medicine, said the discovery of pain "synaesthesia" in phantom limb sufferers could lead to new treatments for the perplexing condition. "We thought up to now one reason phantom pain was brought on was because seeing another person in pain is simply distressing. But now we think that when they see that person in pain they actually feel that pain," she said.
The brain's adaptive systems typically activate emotional responses to pain in others, or what is commonly described as empathy. But it is now thought those systems in phantom limb sufferers are disinhibited, causing them to not only "feel" someone's pain but to experience it. "Perhaps it is because they have had a traumatic, painful experience in losing a limb that their brain is more prone to feeling pain when they see another person in pain," Ms Giummarra said.
The discovery, to be published in an academic text, was found in a small proportion of the almost 300 amputees studied across Australia. More than 90% reported suffering from phantom pain, which is thought to result from crossed wires in the brain misinterpreting signals from one part of the body as those coming from the lost limb. Monash University researchers are planning further study of synaesthesia, including trials of new treatments for sufferers of phantom limb pain.
Dr Michael Chou, head of the amputee rehabilitation unit at Caulfield General Medical Centre, which treats up to 1500 patients a year, said the study's findings could spur new treatments for phantom limb pain. "It opens up the opportunity to include other groups of medications that might help, such as drugs psychiatrists use to calm people's moods," he said.
Bob Metter, 87, of Elsternwick, had doctors remove his left leg, which was already incapacitated from polio, after breaking it badly 12 years ago. His phantom pain can be triggered by violent scenes in films or from hearing about a painful experience.
"My son was here two days ago after being to the dentist to have two posts put in his jawbone. When he told me about them I started to feel the pain again and told him to stop. The pain ran through the leg like an electric shock," Mr Metter said. "I can be watching television and see some documentary where a little girl is about to have an inoculation, and when I see her wince I will feel pain."(Copyright (C) TheAge.Com.AU, text by Peter Munro, June 2008).
Personally, I get that as well. When I am watching a cruel scene in a movie, or when people are upset or nervous, my extremely empathic system immediately gets that, picks it up - and I feel it being boosted as a massive increase in a tight sting of my phantom sensation that will seamlessly roar into a full pain if I do not back away, back out or stay clear.
From Fitzgibbon BM et al. (2010) High incidence of synaesthesia for pain in amputees. Neuropsychologia 48:3675-3678:
Synaesthesia is a phenomenon in which an unusual perceptual experience occurs in response to sensory stimulation (Rich & Mattingley, 2002; Ward & Mattingley, 2006). Synaesthesia differs from most pathological conditions as it involves the elicitation of an event, i.e. a positive symptom, rather than the lack of a function. Further, it is different from other positive symptoms, such as hallucinations, as it does not occur within a psychiatric or neurological context. In this paper we provide the first attempt to determine the incidence and characteristics of the newly documented synaesthesia for pain:whenthe observation or imagination of pain in another results in the actual experience of pain in oneself (Fitzgibbon, Giummarra, Georgiou-Karistianis, Enticott, & Bradshaw, 2010). We believe that synaesthesia for pain is a phenomenon related to more well-known forms of synaesthesia as it not common to the general population, it seems to occur involuntarily, and the synaesthetic experience is similar to another perceptual experience (for synaesthesia criteria, see Ward & Mattingley, 2006).
Consistent with previous research on PLP (e.g., Ehde et al., 2000; Ephraim, Wegener, MacKenzie, Dillingham, & Pezzin, 2005), our sample reported a high rate of phantom pain: 76% experienced PLP in the preceding week. Of the overall sample, synaesthetic pain was triggered in 16.2% of participants (see Table 1 for clinical characteristics). There were no significant differences between those who reported pain synaesthesia (n = 12) and those who did not (n = 62), apart from age (F(1, 72) = 4.10, p < .05): pain synaesthetes were older (M: 62.5, SD: 13.7) than those who did not report pain synaesthesia (M: 55.18, SD: 10.98). Although one obvious hypothesis is that this difference is due to time since amputation, there was no between-group difference in time since amputation, and no correlation between age and time since amputation (r = .08, p > .05). Of the 12 pain synaesthetes, 83.3% reported their synaesthetic pain was triggered in response to the sight of another person in pain, and for 66.7% synaesthetic pain was triggered in response to imagining another person in pain (data overlapping). Only 16.7% indicated that imagining another person in pain was the sole trigger. This suggests a potential hierarchy whereby the direct observation of another person in pain is more likely to trigger synaesthetic pain than imagining pain in another. Synaesthetic pain was most commonly triggered in response to any pain observed or imagined (90.9%) rather than to pain that is (a) similar to the pain associated with the individuals amputation (e.g., cause of amputation), or (b) located in a limb corresponding to the amputated limb. Further, synaesthetic pain was most commonly experienced in response to anyone in pain (63.6%), rather than just loved ones or others similar in race or gender. This suggests that the actual identity of the observed/imagined sufferer is irrelevant. This is inconsistent with literature describing empathy for pain where it is suggested that, for example, neural response is decreased when observing racial out-group members in pain compared to racial ingroups members (Avenanti, Sirigu, & Aglioti, 2010; Xu, Zuo, Wang, & Han, 2009). For the majority of participants with synaesthesia for pain (75%), synaesthetic pain was experienced in their phantom while in addition to, or exclusively, 41.7% experienced it in their residual limb, and 8.3% in the same body part (and on the same side) as the location of pain in the other person. When asked if the synaesthetic experience is similar to or different to spontaneous PLP, 57.1% stated that there was no difference, 14.3% reported it to be more intense, and 28.6% selected other. Finally, 41.7% of this group reported experiencing other types of synaesthetic-like experiences (e.g., letters, numbers and/or words having consistent colours), and 75% had symptoms of PTSD (e.g., re-experiencing the event that led to amputation).
Our findings suggest experiencing pain when observing or imagining pain in another is not uncommon among amputees. The high rate of this synaesthesia for pain (16.2%) is consistent with reports of synaesthesia for touch (see Banissy, Cohen Kadosh, Maus, Walsh, & Ward, 2009). In a large sample (n = 567) of undergraduate students, Banissy et al. found 10.8% of the sample reported experiencing touch when observing touch to another. Further investigation into these students validated that 1.6% of the cases were mirror-touch synaesthetes, placing mirror-touch synaesthesia as one of the most common forms of synaesthesia. It is possible our high rate of synaesthesia for pain (and other types of synaesthesia-like experiences) in amputees may also be reduced upon further investigation due to the likely incidence of false positives, as observed by Banissy et al. in their initial collection of self-report data. On the other hand, it is also possible that our high rate is reflective of the fact that we have explored a specific group of interest (amputees) whose history of trauma or chronic pain make synaesthesia for pain more frequent than other forms of synaesthesia found in the general population.
As all reports of synaesthesia for pain in amputees have followed a painful and/or traumatic experience (i.e., amputation), this prior pain may be the cause of such disinhibition, perhaps as a byproduct of hypervigiliance to pain cues. There is some evidence that mirror systems can be modulated by sensorimotor learning (Catmur, Walsh, & Heyes, 2007), consistent with the idea that the mirror system can be affected by experience. This explanation, however, does not encompass a common mechanism for synaesthetic pain in non-amputee populations (see Derbyshire & Osborn, 2010). It may be that disinhibition of mirror-systems can be produced via traumatic events or occur naturally in some people, perhaps through a genetic predisposition as is thought to happen for other forms of synaesthesia (Rich & Mattingley, 2002).
The results clearly show that when a person who has had a limb amputated watches the corresponding intact limb of another person being touched, the former person experiences it in his or her phantom limb. The referral was organized topographically, especially with Patient 4, although with poor resolution between the third and fourth digits. The other 3 patients also demonstrated topography but were not tested systematically for this purpose. Stroking along the length of the index finger, however, produced a sensation of being stroked on the phantom index finger in all 4 patients.