Seeing the Phantom: A Functional Magnetic Resonance Imaging Study of a Supernumerary Phantom Limb

Laboratory of Experimental Neuropsychology, Geneva University Hospitals and Faculty of Medicine, Geneva, Switzerland.
Annals of Neurology (Impact Factor: 9.98). 06/2009; 65(6):698-705. DOI: 10.1002/ana.21647
Source: PubMed


Supernumerary phantom limb (SPL) is a rare neurological manifestation where patients with a severe stroke-induced sensorimotor deficit experience the illusory presence of an extra limb that duplicates a real one. The illusion is most often experienced as a somesthetic phantom, but rarer SPLs may be intentionally triggered or seen. Here, we report the case of a left visual, tactile, and intentional SPL caused by right subcortical damage in a nondeluded woman.
Using functional magnetic resonance imaging, we investigated the multimodal nature of this phantom, which the patient claimed to be able see, use, and move intentionally. The patient participated in a series of sensorimotor and motor imagery tasks involving the right, the left plegic, and the SPL's hand.
Right premotor and motor regions were engaged when she imagined that she was scratching her left cheek with her left plegic hand, whereas when she performed the same task with the SPL, additional left middle occipital areas were recruited. Moreover, comparison of responses induced by left cheek (subjectively feasible) versus right cheek scratching (reportedly unfeasible movement) with the SPL demonstrated significant activation in right somesthetic areas.
These findings demonstrate that intentional movements of a seen and felt SPL activate premotor and motor areas together with visual and sensory cortex, confirming its multimodal dimension and the reliability of the patient's verbal reports. This observation, interpreted for cortical deafferentation/disconnection caused by subcortical brain damage, constitutes a new but theoretically predictable entity among disorders of bodily awareness.

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    • "SPLs and phantom limb sensations are thought to be a disruption of such normal bodily perceptions. SPLs are not infrequently reported after brain pathology and the main postulation is thought to be due to reorganization of the primary somatosensory cortex and subsequent deterioration of normal body schema [9]. "
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    ABSTRACT: Supernumerary phantom limb (SPL) resulting from spinal cord lesions are very rare, with only sporadic and brief descriptions in the literature. Furthermore, the reported cases of SPL typically occurred in neurologically incomplete spinal cord patients. Here, we report a rare case of SPL with phantom limb pain that occurred after traumatic spinal cord injury in a neurologically complete patient. After a traffic accident, a 43-year-old man suffered a complete spinal cord injury with a C6 neurologic level of injury. SPL and associated phantom limb pain occurred 6 days after trauma onset. The patient felt the presence of an additional pair of legs that originated at the hip joints and extended medially, at equal lengths to the paralyzed legs. The intensity of SPL and associated phantom limb pain subsequently decreased after visual-tactile stimulation treatment, in which the patient visually identified the paralyzed limbs and then gently tapped them with a wooden stick. This improvement continued over the 2 months of inpatient treatment at our hospital and the presence of the SPLs was reduced to 20% of the real paralyzed legs. This is the first comprehensive report on SPLs of the lower extremities after neurologically complete spinal cord injury.
    Annals of Rehabilitation Medicine 12/2013; 37(6):901-6. DOI:10.5535/arm.2013.37.6.901
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    • "N. Bolognini et al. / Neuroscience and Biobehavioral Reviews 37 (2013) 269–278 275 Khateb et al. (2009) described a post-stroke supernumerary phantom limb characterized by the presence of motor, tactile, and visual components caused by right subcortical capsulolenticular damage. Using fMRI, the authors showed that intentional movements of a seen and felt supernumerary phantom limb activated premotor and motor areas together with visual and somatosensory cortices (Khateb et al., 2009). The emergence of supernumerary phantoms has been linked to a failure to correctly integrate multisensory and motor information to generate a normal experience of self-body parts; a mechanism functionally akin to that at the basis of the autoscopic phenomena (Brugger, 2006). "
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    ABSTRACT: Current neuropsychological evidence demonstrates that damage to sensory-specific and heteromodal areas of the brain not only disrupt the ability of combining sensory information from multiple sources, but can also cause altered multisensory experiences. On the other hand, there is also evidence of behavioural benefits induced by spared multisensory mechanisms. Thus, crossmodal plasticity can be viewed in both an adaptive and maladaptive context. The emerging view is that different crossmodal plastic changes can result following damage to sensory-specific and heteromodal areas, with post-injury crossmodal plasticity representing an attempt of a multisensory system to reconnect the various senses and by-pass injured areas. Changes can be considered adaptive when there is compensation for the lesion-induced sensory impairment. Conversely, it may prove maladaptive when atypical or even illusory multisensory experiences are generated as a result of re-arranged multisensory networks. This theoretical framework posits new intriguing questions for neuropsychological research and places greater emphasis on the study of multisensory phenomena within the context of damage to large-scale brain networks, rather than just focal damage alone.
    Neuroscience & Biobehavioral Reviews 12/2012; 37(3). DOI:10.1016/j.neubiorev.2012.12.006 · 8.80 Impact Factor
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    • "This distinct symptomatology has not been reported before. Usually PL are either static or show intentional or unintentional motor functions (Staub et al., 2006; Khateb et al., 2009; Antoniello et al., 2010) or as reported in the case of a patient with a ruptured aneurysm, mirror the movements of the healthy limb with some delay (Hari et al., 1998). "
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    ABSTRACT: Supernumerary phantom limbs, that is, the awareness of an illusory extra limb is a fascinating neurologic symptom that has been described in a number of neurologic diseases including stroke, spinal injury, and epilepsy. Herein we report a case of a 70-year-old male patient with new-onset focal seizures with left-sided supernumerary phantom arm and leg as the only seizure manifestation. Ictal single-photon emission computed tomography (SPECT) revealed a hyperperfusion in the right temporoparietal junction and allowed localization of the seizure-onset zone. This report is accompanied by a discussion of phenomenology and terminology in the context of existing literature.
    Epilepsia 08/2011; 52(8):e97-e100. DOI:10.1111/j.1528-1167.2011.03156.x · 4.57 Impact Factor
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