scholarly journals Reassessing referred sensations following peripheral deafferentation and the role of cortical reorganisation

2021 ◽  
Author(s):  
Elena Amoruso ◽  
Devin B. Terhune ◽  
Maria Kromm ◽  
Stephen Kirker ◽  
Dollyane Muret ◽  
...  
Keyword(s):  
Upper Limb ◽  
Phantom Limb ◽  
Whole Body ◽  
Limb Amputation ◽  
Body Parts ◽  
Demand Characteristics ◽  
Wide Range ◽  
Cord Injury ◽  
Self Reports ◽  
The Face

ABSTRACTBackground and ObjectivesTactile sensations referred to body parts other than those stimulated have been repeatedly described across a wide range of deafferentation and neuropathic pain conditions, including amputation, complex regional pain syndrome, spinal cord injury, and brachial plexus avulsion. Common to all interpretations of referred sensations is the notion that they result from central nervous system (CNS) reorganisation. For example, in amputees, sensations referred to the phantom limb following touches on the face have been classically interpreted as the perceptual correlate of cortical remapping of the face into the neighbouring missing-hand territory in primary somatosensory cortex (S1). Here, using the prominent model of acquired upper-limb amputation, we investigated whether referred sensations reports are associated with cortical remapping or can instead be attributed to demand characteristics (e.g., compliance, expectation, and suggestion), which have been shown to greatly influence self-reports of bodily sensations and were uncontrolled in previous assessments.MethodsUnilateral upper-limb amputees (N=18), congenital one-handers (N=19), and two-handers (N=20) were repeatedly stimulated with PC-controlled vibrations on ten body-parts and asked to report on each trial the occurrence of any concurrent sensations on their hand(s). To further manipulate expectations, we gave participants the suggestion that some of these vibrations had a higher probability to evoke referred sensations. To evaluate remapping, we analysed fMRI data in S1 from two tasks involving movement of facial and whole-body parts, using univariate and multivariate approaches.ResultsThe frequency and distribution of reported referred sensations were similar across groups, with higher frequencies in the high expectancy condition. In amputees, referred sensations were evoked by stimulation of multiple body-parts and reported in both the intact and phantom hand. The group profiles for referred sensations reports were not consistent with the observed patterns of S1 remapping.DiscussionThese findings weaken the interpretation of referred sensations as a perceptual consequence of post-deafferentation CNS reorganisation and reveal the need to account for demand characteristics when evaluating self-reports of anomalous perceptual phenomena for both research and clinical assessments purposes.

Adult limb and breast amputees’ experience and descriptions of phantom phenomena—A qualitative study

2010 ◽  
Vol 1 (1) ◽  
pp. 43-49 ◽  
Author(s):  
Berit Björkman ◽  
Staffan Arnér ◽  
Iréne Lund ◽  
Lars-Christer Hydén
Keyword(s):  
Brain Imaging ◽  
Imaging Techniques ◽  
Functional Brain Imaging ◽  
Phantom Limb ◽  
Limb Amputation ◽  
Phantom Pain ◽  
Body Parts ◽  
Structured Interviews ◽  
Functional Brain ◽  
Wide Range

AbstractBackgroundPhantom phenomena – pain or other sensations appearing to come from amputated body parts – are frequent consequences of amputation and can cause considerable suffering. Also, stump pain, located in the residual limb, is in the literature often related to the phantom phenomena. The condition is not specific to amputated limbs and has, to a lesser extent, been reported to be present after radical surgery in other body parts such as breast, rectum and teeth.Multi-causal theories are used when trying to understand these phenomena, which are recognized as the result of complex interaction among various parts of the central nervous system confirmed in studies using functional brain imaging techniques.Functional brain imaging has yielded important results, but without certainty being related to phantom pain as a subjective clinical experience.There is a wide range of treatment methods for the condition but no documented treatment of choice.AimsIn this study a qualitative, explorative and prospective design was selected, in the aim to understand the patients’ personal experience of phantom phenomena.The research questions focused at how patients affected by phantom pain and or phantom sensations describe, understand, and live with these phenomena in their daily life.This study expanded ‘phantom phenomena’ to also encompass phantom breast phenomenon. Since the latter phenomenon is not as well investigated as the phantom limb, there is clinical concern that this is an underestimated problem for women who have had breasts removed.MethodsThe present study forms the first part of a larger, longitudinal study. Only results associated with data from the first interviews with patients, one month after an amputation, are presented here. At this occasion, 28 patients who had undergone limb amputation (20) or mastectomy (8) were interviewed. The focused, semi-structured interviews were recorded, transcribed, and then analyzed using discourse-narrative analysis.ResultsThe interviewees had no conceptual problems in talking about the phenomena or distinguishing between various types of discomfort and discomfort episodes. Their experience originated from a vivid, functioning body that had lost one of its parts. Further, the interviewees reported the importance of rehabilitation and advances in prosthetic technology. Loss of mobility struck older amputees as loss of social functioning, which distressed them more than it did younger amputees. Phantom sensations, kinetic and kinesthetic perceptions, constituted a greater problem than phantom pain experienced from the amputated body parts. The descriptions by patients who had had mastectomies differed from those by patients who had lost limbs in that the phantom breast could be difficult to describe and position spatially.The clinical implication of this study is that when phantom phenomena are described as everyday experience, they become a psychosocial reality that supplements the definition of phantom phenomena in scientific literature and clinical documentation.ConclusionsThere is a need for clinical dialogues with patients, which besides, providing necessary information about the phenomena to the patients creates possibilities for health professionals to carefully listen to the patients’ own descriptions of which functional losses or life changes patients fear the most. There is a need for more qualitative studies in order to capture the extreme complexity of the pain–control system will be highlighted.

scholarly journals Successful application of burst spinal cord stimulation for refractory upper limb pain: a case series

2021 ◽  
Vol 49 (3) ◽  
pp. 030006052110040
Author(s):  
Kuen Su Lee ◽  
Yoo Kyung Jang ◽  
Gene Hyun Park ◽  
In Jae Jun ◽  
Jae Chul Koh
Keyword(s):  
Spinal Cord ◽  
Upper Limb ◽  
Spinal Cord Stimulation ◽  
Therapeutic Potential ◽  
Case Series ◽  
Limb Amputation ◽  
Intractable Pain ◽  
Limb Pain ◽  
Cord Injury ◽  
Upper Limb Pain

Spinal cord stimulation (SCS) has been used to treat sustained pain that is intractable despite various types of treatment. However, conventional tonic waveform SCS has not shown promising outcomes for spinal cord injury (SCI) or postamputation pain. The pain signal mechanisms of burst waveforms are different to those of conventional tonic waveforms, but few reports have presented the therapeutic potential of burst waveforms for the abovementioned indications. This current case report describes two patients with refractory upper limb pain after SCI and upper limb amputation that were treated with burst waveform SCS. While the patients could not obtain sufficient therapeutic effect with conventional tonic waveforms, the burst waveforms provided better pain reduction with less discomfort. However, further studies are necessary to better clarify the mechanisms and efficacy of burst waveform SCS in patients with intractable pain.

scholarly journals mTOR Signaling at the Crossroad between Metazoan Regeneration and Human Diseases

2020 ◽  
Vol 21 (8) ◽  
pp. 2718 ◽  
Author(s):  
Yasmine Lund-Ricard ◽  
Patrick Cormier ◽  
Julia Morales ◽  
Agnès Boutet
Keyword(s):  
Evolutionary Biology ◽  
Mammalian Target Of Rapamycin ◽  
Mtor Pathway ◽  
Mtor Signaling ◽  
Human Diseases ◽  
Whole Body ◽  
Body Parts ◽  
Animal Kingdom ◽  
Structure Damage ◽  
Wide Range

A major challenge in medical research resides in controlling the molecular processes of tissue regeneration, as organ and structure damage are central to several human diseases. A survey of the literature reveals that mTOR (mechanistic/mammalian target of rapamycin) is involved in a wide range of regeneration mechanisms in the animal kingdom. More particularly, cellular processes such as growth, proliferation, and differentiation are controlled by mTOR. In addition, autophagy, stem cell maintenance or the newly described intermediate quiescence state, Galert, imply upstream monitoring by the mTOR pathway. In this review, we report the role of mTOR signaling in reparative regenerations in different tissues and body parts (e.g., axon, skeletal muscle, liver, epithelia, appendages, kidney, and whole-body), and highlight how the mTOR kinase can be viewed as a therapeutic target to boost organ repair. Studies in this area have focused on modulating the mTOR pathway in various animal models to elucidate its contribution to regeneration. The diversity of metazoan species used to identify the implication of this pathway might then serve applied medicine (in better understanding what is required for efficient treatments in human diseases) but also evolutionary biology. Indeed, species-specific differences in mTOR modulation can contain the keys to appreciate why certain regeneration processes have been lost or conserved in the animal kingdom.

scholarly journals Tactile innervation densities across the whole body

2020 ◽  
Author(s):  
Giulia Corniani ◽  
Hannes P. Saal
Keyword(s):  
Whole Body ◽  
Fiber Types ◽  
Body Parts ◽  
Tactile Information ◽  
Body Regions ◽  
Afferent Fibers ◽  
The Face ◽  
The Brain ◽  
Palmar Skin ◽  
Root Fiber

The skin is our largest sensory organ and innervated by afferent fibers carrying tactile information to the spinal cord and onto the brain. The density with which different classes of tactile afferents innervate the skin is not constant but varies considerably across different body regions. However, precise estimates of innervation density are only available for some body parts, such as the hands, and estimates of the total number of tactile afferent fibers are inconsistent and incomplete. Here we reconcile different estimates and provide plausible ranges and best estimates for the number of different tactile fiber types innervating different regions of the skin, using evidence from dorsal root fiber counts, microneurography, histology, and psychophysics. We estimate that the skin across the whole body is innervated by approximately 230,000 tactile afferent fibers (plausible range: 200,000-270,000). 15% innervate the palmar skin of both hands and 19% the region surrounding the face and lips. Around 60% of all tactile fibers are slowly-adapting, while the rest are fastadapting. Innervation density correlates well with psychophysical spatial acuity across different body regions, and additionally, on hairy skin, with hair follicle density. Innervation density is also weakly correlated with the size of the cortical somatotopic representation, but cannot fully account for the magnification of the hands and the face.

scholarly journals Tactile innervation densities across the whole body

2020 ◽  
Vol 124 (4) ◽  
pp. 1229-1240
Author(s):  
Giulia Corniani ◽  
Hannes P. Saal
Keyword(s):  
Whole Body ◽  
Fiber Types ◽  
Body Parts ◽  
Tactile Information ◽  
Body Regions ◽  
Afferent Fibers ◽  
The Face ◽  
The Brain ◽  
Palmar Skin ◽  
Root Fiber

The skin is our largest sensory organ and innervated by afferent fibers carrying tactile information to the spinal cord and onto the brain. The density with which different classes of tactile afferents innervate the skin is not constant but varies considerably across different body regions. However, precise estimates of innervation density are only available for some body parts, such as the hands, and estimates of the total number of tactile afferent fibers are inconsistent and incomplete. Here we reconcile different estimates and provide plausible ranges and best estimates for the number of different tactile fiber types innervating different regions of the skin, using evidence from dorsal root fiber counts, microneurography, histology, and psychophysics. We estimate that the skin across the whole body of young adults is innervated by ∼230,000 tactile afferent fibers (plausible range: 200,000–270,000), with a subsequent decrement of 5–8% every decade due to aging. Fifteen percent of fibers innervate the palmar skin of both hands and 19% the region surrounding the face and lips. Slowly and fast-adapting fibers are split roughly evenly, but this breakdown varies with skin region. Innervation density correlates well with psychophysical spatial acuity across different body regions, and, additionally, on hairy skin, with hair follicle density. Innervation density is also weakly correlated with the size of the cortical somatotopic representation but cannot fully account for the magnification of the hands and the face.

Reorganization of cortical blood flow and transcranial magnetic stimulation maps in human subjects after upper limb amputation

1994 ◽  
Vol 72 (5) ◽  
pp. 2517-2524 ◽  
Author(s):  
J. J. Kew ◽  
M. C. Ridding ◽  
J. C. Rothwell ◽  
R. E. Passingham ◽  
P. N. Leigh ◽  
...  
Keyword(s):  
Blood Flow ◽  
Transcranial Magnetic Stimulation ◽  
Upper Limb ◽  
Magnetic Stimulation ◽  
Human Subjects ◽  
Phantom Limb ◽  
Limb Amputation ◽  
Cortical Function ◽  
Positron Emission ◽  
Group 5

1. Two complimentary techniques were used to study cortical function in six human upper limb amputees: positron emission tomographic (PET) measurements of regional cerebral blood flow (rCBF) were made in subjects during limb movements to study activation of the primary motor (M1), primary somatosensory (S1), and association cortices; and electromyographic responses to transcranial magnetic stimulation (TMS) were measured in proximal upper limb muscles to assess the excitability of corticospinal neurons in subjects at rest. 2. To explore possible cortical mechanisms governing the phantom limb phenomenon, PET and TMS findings were compared between subjects with acquired, traumatic upper limb amputations (n = 3), in whom phantom limb symptoms were prominent, and congenital upper limb amputees (n = 3) without phantom limbs. 3. Paced shoulder movements were associated with significant blood flow increases in the contralateral M1/S1 cortex of both groups of amputees. In traumatic amputees, these increases were present over a wider area and were of significantly greater magnitude in the partially deafferented cortex contralateral to the amputation. In congenital amputees blood flow increases were also present over a wider area in the partially deafferented M1/S1 cortex, but their magnitude was not significantly different from that in the normally afferented M1/S1 cortex. 4. Abnormal blood flow increases also were present in the partially deafferented M1/S1 cortex of traumatic amputees during movement of the ipsilateral, intact arm. Abnormal ipsilateral M1/S1 responses were not present during movement of the intact arm in the congenital group. 5. TMS studies showed that the abnormal blood flow increases in the partially deafferented M1 cortex of traumatic amputees were associated with increased corticospinal excitability.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Characterising phantom limb phenomena in upper limb amputees

2001 ◽  
Vol 25 (3) ◽  
pp. 235-242 ◽  
Author(s):  
C. M. Fraser ◽  
P. W. Halligan ◽  
I. H. Robertson ◽  
S. G. B. Kirker
Keyword(s):  
Upper Limb ◽  
Trigger Points ◽  
Phantom Limb ◽  
Limb Amputation ◽  
Upper Limb Amputation ◽  
Significant Relationships ◽  
Stump Pain ◽  
Descriptive Survey ◽  
Clinic Population ◽  
Cortical Reorganisation

A systematic descriptive survey was carried out on a clinic population with acquired upper limb amputation in which clear distinctions were made between phantom experiences, pre-amputation pain and stump pain. It was found that of 76 participants 96% reported phantom experiences and 84% were currently experiencing phantom limb phenomena (PLP). Sixty-nine percent (69%) of those currently experiencing phantom phenomena stated that the phantoms were painful. Significant relationships were found between frequency of phantom experiences and side and level of amputation. In addition, the presence of ‘trigger’ points reported by a sub group of participants was found to be associated with the frequency of phantoms and painful phantoms. This finding could provide support for cortical reorganisation post amputation. It is suggested that detailed individual ‘profiling’ of phantom experiences is important and would have the following implications: it would contribute to existing knowledge and provide new insights into the central nervous system's reorganisation post-amputation; it would provide an accurate way of representing amputees’ anomalous perceptions; it would alert health professionals to the presence, variety and extent of PLP following amputation.

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