Nutritional follow-up of patients with head and neck cancer

Head and neck (H&N) cancer constitutes approximately 5.1% of all cancers worldwide and 2.2% in Sweden. It is a heterogeneous group of malignant tumours with differences in natural history and prognosis. The treatment is often multiple, where the main treatment modalities are external beam radiotherapy (RT) and surgery. For many patients with H&N cancer, nutritional problems are an immense and complex range of challenges. If the patient cannot swallow and the gastrointestinal tract is functioning normally, nutritional support is mainly given with enteral nutrition. The most common way to administer enteral feeding is via a polyurethane nasogastric feeding tube (NGT) or via a percutaneous endoscopic gastrostomy (PEG) tube. In this thesis different cohorts of patients with H&N cancer have been studied with the ultimate goal to identify patients in need of nutritional support and to improve nutritional surveillance. Study I The predictive value of systematic inflammatory and metabolic markers was prospectively studied in 27 patients with H&N cancer undergoing RT. All patients lost body weight with the greatest loss at the end of RT. Highly sensitive C-reactive protein (hsCRP) increased during RT. None of the systemic inflammatory and metabolic markers was significantly associated with body weight loss. Study II A retrospective study of consecutive patients who received a PEG tube is presented. Of the 171 patients planned for PEG, 156 were successfully carried out, while the attempt failed in 15 patients. The duration of PEG tube usage varied considerably. Complications were seen in 42% (n=65) of the patients. Seven patients (5%) had fatal complications related directly or indirectly to the PEG tube placement, 33 patients (21%) had severe complications and 25 patients (16%) had minor complications. Study III Consecutive patients (n=157) with H&N cancer who were seen for nutritional control at a nurse-led outpatient clinic were evaluated for factors known to contribute to body weight loss. Nadir of body weight was observed at 6 months after RT. In total, 92 patients (59%) with no evidence of residual tumour after treatment received enteral nutrition. Patients that maintained oral feeding did not lose as much body weight as patients who received enteral nutrition. Tumour stage was the only independent predictive factor of maximum body weight loss. Body weight loss was not found to be associated with post-operative infections or mortality. Study IV Using a descriptive, prospective design, semi-structured interviews about what in life is influenced by disease and feeding (oral feeding, NGT or PEG) were conducted in 41 patients with H&N cancer. More than 50% of the patients manifested eating-related problems. No significant differences in life areas (e.g., fatigue, pain, nutrition and social and family life) influenced by disease were observed over time between oral feeding and enteral nutrition. Furthermore, no differences were noted between patients having NGT or PEG, except that patients with NGT expressed negative views regarding social limitations and patients with PEG felt confined by the tube. The conclusions of this thesis are that body weight and CRP are valuable variables to follow-up. The risk for complications because of PEG ought to be considered when deciding on an enteral nutrition method of feeding. NGT should be regarded as the first choice of enteral nutrition in patients with an expected limited time of tube feeding, whereas in patients in which prolonged treatment is needed PEG could be the choice for most patients. The extended body weight loss after treatment indicates that a nutritional surveillance programme (e.g. managed by a nurse-led outpatient clinic) is important before, during but not in the least after treatment

Experimental Induction of a Perceived “Telescoped” Limb Using a Full-Body Illusion

Phantom limbs refer to the sensation that an amputated or missing limb is still attached to the body. Phantom limbs may be perceived as continuous with the stump so as to resemble a normal limb, or as “telescoped” with the more distal portion of the phantom being perceived as having withdrawn within the stump. Telescoping tends to be related to increased levels of phantom pain, making it a clinically relevant phenomenon to investigate. In the current study we show that a full-body illusion can be used to induce the sensation of a telescoped limb in healthy individuals. For the induction of the full-body illusion, participants saw the body of a mannequin from a first person perspective while being subjected to synchronized visuo-tactile stimulation through stroking. Crucially, the mannequin was missing its left hand so as to resemble an amputee. By manipulating the positioning of the strokes applied to the mannequin's stump with respect to the participants’ hand we were able to evoke the sensation of the participants’ hand being located either below the stump or, more crucially, “inside” the stump, i.e., telescoped. In three separate experiments these effects were supported by complementary subjective data from questionnaires, verbally reported perceived location of the hand, and manual pointing movements indicating hand position (proprioceptive drift). Taken together our results show that healthy individuals can experience the body of an upper limb amputee as their own, and that this can be associated with telescoping sensations. This is a theoretically important observation as it shows that ownership of an entire body can be evoked in the context of gross anatomical incongruence for a single limb, and that telescoping sensations occur as a consequence of the body representation system trying to reduce this incongruence. Furthermore, the present study might provide a new platform for future studies of the relationship between telescoping and phantom pain in amputees

Moving a Rubber Hand that Feels Like Your Own: A Dissociation of Ownership and Agency

During voluntary hand movement, we sense that we generate the movement and that the hand is a part of our body. These feelings of control over bodily actions, or the sense of agency, and the ownership of body parts are two fundamental aspects of the way we consciously experience our bodies. However, little is known about how these processes are functionally linked. Here, we introduce a version of the rubber hand illusion in which participants control the movements of the index finger of a model hand, which is in full view, by moving their own right index finger. We demonstrated that voluntary finger movements elicit a robust illusion of owning the rubber hand and that the senses of ownership and agency over the model hand can be dissociated. We systematically varied the relative timing of the finger movements (synchronous versus asynchronous), the mode of movement (active versus passive), and the position of the model hand (anatomically congruent versus incongruent positions). Importantly, asynchrony eliminated both ownership and agency, passive movements abolished the sense of agency but left ownership intact, and incongruent positioning of the model hand diminished ownership but did not eliminate agency. These findings provide evidence for a double dissociation of ownership and agency, suggesting that they represent distinct cognitive processes. Interestingly, we also noted that the sense of agency was stronger when the hand was perceived to be a part of the body, and only in this condition did we observe a significant correlation between the subjects’ ratings of agency and ownership. We discuss this in the context of possible differences between agency over owned body parts and agency over actions that involve interactions with external objects. In summary, the results obtained in this study using a simple moving rubber hand illusion paradigm extend previous findings on the experience of ownership and agency and shed new light on their relationship

Visuo-thermal congruency modulates the sense of body ownership

Thermosensation has been redefined as an interoceptive modality that provides information about the homeostatic state of the body. However, the contribution of thermosensory signals to the sense of body ownership remains unclear. Across two rubber hand illusion (RHI) experiments (N = 73), we manipulated the visuo-thermal congruency between the felt and seen temperature, on the real and rubber hand respectively. We measured the subjectively experienced RHI, the perceived hand location and temperature of touch, and monitored skin temperature. We found that visuo-thermal incongruencies between the seen and felt touch reduced the subjective and behavioural RHI experience (Experiment 1). Visuo-thermal incongruencies also gave rise to a visuo-thermal illusion effect, but only when the rubber hand was placed in a plausible position (Experiment 2) and when considering individual differences in interoceptive sensibility. Thus, thermosensation contributes to the sense of body ownership by a mechanism of dynamic integration of visual and thermosensory signals.Göran Gustafsson FoundationSwedish Research CouncilEuropean Research Council under the European Union’s horizon 2020 research and innovation programme (SELF-UNITY)Marie Skłodowska-Curie Intra-European Individual Fellowship (HOMEOTHERMIC SELF)Accepte

The role of the skin in interoception : a neglected organ?

In the past two decades, interoception has received increasing attention in the fields of psychology and cognitive science, as well as neuroscience and physiology. A plethora of studies adopted the perception of cardiac signals as a proxy for interoception. However, recent findings have cast doubt to the methodological and intrinsic validity of the tasks used thus far. Therefore, there is an ongoing effort to improve the existing cardiac interoceptive tasks and to identify novel channels to target the perception of the physiological state of the body. Amid such scientific abundancy, one could question whether the field has been partially neglecting one of our widest organs in terms of dimensions and functions, the skin. According to some views grounded on anatomical and physiological evidence, skin-mediated signals such as affective touch, pain, and temperature have been re-defined as interoceptive. Nevertheless, there is no agreement at this regard. Here, we discuss some of the anatomical, physiological, and experimental arguments supporting the scientific study of interoception by means of skin-mediated signals. We argue that more attention should be paid to the skin as a sensory organ that monitors the bodily physiological state, and further propose thermosensation as a particularly attractive model of skin-mediated interoception.European Research Council under the European Union’s horizon 2020 research and innovation programme (SELF-UNITY)Marie Skłodowska-Curie Intra-European Individual Fellowship (HOMEOTHERMIC SELF)Accepte

Mental Imagery Induces Cross-Modal Sensory Plasticity and Changes Future Auditory Perception

Can what we imagine in our minds change how we perceive the world in the future? A continuous process of multisensory integration and recalibration is responsible for maintaining a correspondence between the senses (e.g., vision, touch, audition) and, ultimately, a stable and coherent perception of our environment. This process depends on the plasticity of our sensory systems. The so-called ventriloquism aftereffect—a shift in the perceived localization of sounds presented alone after repeated exposure to spatially mismatched auditory and visual stimuli—is a clear example of this type of plasticity in the audiovisual domain. In a series of six studies with 24 participants each, we investigated an imagery-induced ventriloquism aftereffect in which imagining a visual stimulus elicits the same frequency-specific auditory aftereffect as actually seeing one. These results demonstrate that mental imagery can recalibrate the senses and induce the same cross-modal sensory plasticity as real sensory stimuli

Weakening the subjective sensation of own hand ownership does not interfere with rapid finger movements

When we perform a movement we generally have a clear distinction between which parts of the world constitute our body and which parts do not. However, how the sense of ownership over our body supports movement is not yet fully understood. We aimed to see whether a sense of ownership over the hand supports the performance of rapid hand movements. In three experiments (n = 48, n = 30, n = 24), we presented participants with congruent and incongruent visuotactile and visuoproprioceptive information regarding their own hand. In keeping with previous experiments, multisensory disintegration resulted in a reduction in the subjective sensation of ownership over the hand, as reflected in questionnaire responses. Following sensory stimulation, participants were required to rapidly abduct their index finger whilst the movement was tracked. We examined the hypothesis that, should a sense of ownership over the limb be necessary for generating rapid movements with that limb, reaction time would increase when hand ownership was reduced, whilst the acceleration and velocity of the movement would decrease. We observed that reductions in own hand ownership did not interfere with rapid index finger abduction, suggesting that the motor system may not be reliant on a subjective sense of ownership over the body in order to generate movement

An Investigation of the Effects of Different Pulse Patterns of Transcutaneous Electrical Nerve Stimulation (TENS) on Perceptual Embodiment of a Rubber Hand in Healthy Human Participants With Intact Limbs.

OBJECTIVE: The aim of this study was to investigate the strength of perceptual embodiment achieved during an adapted version of the rubber hand illusion (RHI) in response to a series of modified transcutaneous electrical nerve stimulation (TENS) pulse patterns with dynamic temporal and spatial characteristics which are more akin to the mechanical brush stroke in the original RHI. MATERIALS AND METHODS: A repeated-measures counterbalanced experimental study was conducted where each participant was exposed to four TENS interventions: continuous pattern TENS; burst pattern TENS (fixed frequency of 2 bursts per second of 100 pulses per second); amplitude-modulated pattern TENS (intensity increasing from zero to a preset level, then back to zero again in a cyclical fashion); and sham (no current) TENS. Participants rated the intensity of the RHI using a three-item numerical rating scale (each item was ranked from 0 to 10). Friedman's analysis of ranks (one-factor repeated measure) was used to test the differences in perceptual embodiment between TENS innervations; alpha was set at p ≤ 0.05. RESULTS: There were statistically significant differences in the intensity of misattribution and perceptual embodiment between sham and active TENS interventions, but no significant differences between the three active TENS conditions (amplitude-modulated TENS, burst TENS, and continuous TENS). Amplitude-modulated and burst TENS produced significantly higher intensity scores for misattribution sensation and perceptual embodiment compared with sham (no current) TENS, whereas continuous TENS did not. CONCLUSION: The findings provide tentative, but not definitive, evidence that TENS parameters with dynamic spatial and temporal characteristics may produce more intense misattribution sensations and intense perceptual embodiment than parameters with static characteristics (e.g., continuous pulse patterns)

Limits of cross-modal plasticity? Short-term visual deprivation does not enhance cardiac interoception, thermosensation, or tactile spatial acuity

In the present study, we investigated the effect of short-term visual deprivation on discriminative touch, cardiac interoception, and thermosensation by asking 64 healthy volunteers to perform four behavioral tasks. The experimental group contained 32 subjects who were blindfolded and kept in complete darkness for 110 minutes, while the control group consisted of 32 volunteers who were not blindfolded but were otherwise kept under identical experimental conditions. Both groups performed the required tasks three times: before and directly after deprivation (or control) and after an additional washout period of 40 minutes, in which all participants were exposed to normal light conditions. Our results showed that short- term visual deprivation had no effect on any of the senses tested. This finding suggests that short-term visual deprivation does not modulate basic bodily senses and extends this principle beyond tactile processing to the interoceptive modalities of cardiac and thermal sensations.Swedish Research Council, 2017-03135Marie Skłodowska-Curie Intra-European Individual Fellowship, 891175Accepte

Illusory obesity triggers body dissatisfaction responses in the insula and anterior cingulate cortex

In today’s Western society, concerns regarding body size and negative feelings towards one’s body are all too common. However, little is known about the neural mechanisms underlying negative feelings towards the body and how they relate to body perception and eating-disorder pathology. Here, we used multisensory illusions to elicit illusory ownership of obese and slim bodies during functional magnetic resonance imaging. The results implicate the anterior insula and the anterior cingulate cortex in the development of negative feelings towards the body through functional interactions with the posterior parietal cortex, which mediates perceived obesity. Moreover, cingulate neural responses were modulated by non-clinical eating-disorder psychopathology and were attenuated in females. These results reveal how perceptual and affective body representations interact in the human brain and may help explain the neurobiological underpinnings of eating-disorder vulnerability in women