Skip Metastases in Papillary Thyroid Cancer

Papillary thyroid carcinoma (PTC) is the most common malignant thyroid disease characterized by a high rate of cervical metastases (30–80%), especially due to paratracheal lymph node involvement. »Skip metastasis« are defined as a lateral lymph node metastasis without central lymph node involvement. The aim of this prospective study was to establish the lateral nodal metastasis pattern according to neck level, general occurrence and significance of skip metastasis in PTC. Forty-two previously untreated patients who presented between 2007 and 2011 with concomitant diagnosis of papillary thyroid cancer and metastatic disease of the lateral neck, underwent total thyroidectomy and central and lateral neck dissection. Skip metastases were encountered in 8(19.5%) patients, four female and four male, with a mean age of 43.3 years. In all patients with lateral skip metastasis, level III nodes were most frequently involved (75%) followed by level IV(50%), while no metastatic disease was found in level IIb. Based on our research, skip metastasis are not uncommon (a lateral lymph node metastasis without central lymph node involvement) and present in approximately 1/5 of PTC patients with cervical lymph node metastasis

Audio-visual interactions in manual and saccadic responses

Chapter 1 introduces the notions of multisensory integration (the binding of information coming from different modalities into a unitary percept) and multisensory response enhancement (the improvement of the response to multisensory stimuli, relative to the response to the most efficient unisensory stimulus), as well as the general goal of the present thesis, which is to investigate different aspects of the multisensory integration of auditory and visual stimuli in manual and saccadic responses. The subsequent chapters report experimental evidence of different factors affecting the multisensory response: spatial discrepancy, stimulus salience, congruency between cross-modal attributes, and the inhibitory influence of concurring distractors. Chapter 2 reports three experiments on the role of the superior colliculus (SC) in multisensory integration. In order to achieve this, the absence of S-cone input to the SC has been exploited, following the method introduced by Sumner, Adamjee, and Mollon (2002). I found evidence that the spatial rule of multisensory integration (Meredith & Stein, 1983) applies only to SC-effective (luminance-channel) stimuli, and does not apply to SC-ineffective (S-cone) stimuli. The same results were obtained with an alternative method for the creation of S-cone stimuli: the tritanopic technique (Cavanagh, MacLeod, & Anstis, 1987; Stiles, 1959; Wald, 1966). In both cases significant multisensory response enhancements were obtained using a focused attention paradigm, in which the participants had to focus their attention on the visual modality and to inhibit responses to auditory stimuli. Chapter 3 reports two experiments showing the influence of shape congruency between auditory and visual stimuli on multisensory integration; i.e. the correspondence between structural aspects of visual and auditory stimuli (e.g., spiky shape and “spiky” sounds). Detection of audio-visual events was faster for congruent than incongruent pairs, and this congruency effect occurred also in a focused attention task, where participants were required to respond only to visual targets and could ignore irrelevant auditory stimuli. This particular type of cross-modal congruency was been evaluated in relation to the inverse effectiveness rule of multisensory integration (Meredith & Stein, 1983). In Chapter 4, the locus of the cross-modal shape congruency was evaluated applying the race model analysis (Miller, 1982). The results showed that the violation of the model is stronger for some congruent pairings in comparison to incongruent pairings. Evidence of multisensory depression was found for some pairs of incongruent stimuli. These data imply a perceptual locus for the cross-modal shape congruency effect. Moreover, it is evident that multisensoriality does not always induce an enhancement, and in some cases, when the attributes of the stimuli are particularly incompatible, a unisensory response may be more effective that the multisensory one. Chapter 5 reports experiments centred on saccadic generation mechanisms. Specifically, the multisensoriality of the saccadic inhibition (SI; Reingold&Stampe, 2002) phenomenon is investigated. Saccadic inhibition refers to a characteristic inhibitory dip in saccadic frequency beginning 60-70 ms after onset of a distractor. The very short latency of SI suggests that the distractor interferes directly with subcortical target selection processes in the SC. The impact of multisensory stimulation on SI was studied in four experiments. In Experiments 7 and 8, a visual target was presented with a concurrent audio, visual or audio-visual distractor. Multisensory audio-visual distractors induced stronger SI than did unisensory distractors, but there was no evidence of multisensory integration (as assessed by a race model analysis). In Experiments 9 and 10, visual, auditory or audio-visual targets were accompanied by a visual distractor. When there was no distractor, multisensory integration was observed for multisensory targets. However, this multisensory integration effect disappeared in the presence of a visual distractor. As a general conclusion, the results from Chapter 5 results indicate that multisensory integration occurs for target stimuli, but not for distracting stimuli, and that the process of audio-visual integration is itself sensitive to disruption by distractors

Alterations in amygdala-prefrontal functional connectivity account for excessive worry and autonomic dysregulation in generalized anxiety disorder

Background: Generalized anxiety disorder (GAD) is characterized by the core symptom of uncontrollable worry. Functional magnetic resonance imaging studies link this symptom to aberrant functional connectivity between the amygdala and prefrontal cortex. Patients with GAD also display a characteristic pattern of autonomic dysregulation. Although frontolimbic circuitry is implicated in the regulation of autonomic arousal, no previous study to our knowledge combined functional magnetic resonance imaging with peripheral physiologic monitoring in these patients to test the hypothesis that core symptoms of worry and autonomic dysregulation in GAD arise from a shared underlying neural mechanism. Methods: We used resting-state functional magnetic resonance imaging and the measurement of parasympathetic autonomic function (heart rate variability) in 19 patients with GAD and 21 control subjects to define neural correlates of autonomic and cognitive responses before and after induction of perseverative cognition. Seed-based analyses were conducted to quantify brain changes in functional connectivity with the right and left amygdala. Results: Before induction, patients showed relatively lower connectivity between the right amygdala and right superior frontal gyrus, right paracingulate/anterior cingulate cortex, and right supramarginal gyrus than control subjects. After induction, such connectivity patterns increased in patients with GAD and decreased in control subjects, and these changes tracked increases in state perseverative cognition. Moreover, decreases in functional connectivity between the left amygdala and subgenual cingulate cortex and between the right amygdala and caudate nucleus predicted the magnitude of reduction in heart rate variability after induction. Conclusions: Our results link functional brain mechanisms underlying worry and rumination to autonomic dyscontrol, highlighting overlapping neural substrates associated with cognitive and autonomic responses to the induction of perseverative cognitions in patients with GAD

Network abnormalities in generalized anxiety pervade beyond the amygdala-prefrontal cortex circuit: insights from graph theory

Generalized anxiety (GAD) has excessive anxiety and uncontrollable worry as core symptoms. Abnormal cerebral functioning underpins the expression and perhaps pathogenesis of GAD: Studies implicate impaired communication between the amygdala and the pre-frontal cortex (PFC). Our aim was to longitudinally investigate whether such network abnormalities are spatially restricted to this circuit or if the integrity of functional brain networks is globally disrupted in GAD. We acquired resting-state functional magnetic resonance imaging data from 16 GAD patients and 16 matched controls at baseline and after 1 year. Using network modelling and graph-theory, whole-brain connectivity was characterized from local and global perspectives. Overall lower global efficiency, indicating sub-optimal brain-wide organization and integration, was present in patients with GAD compared to controls. The amygdala and midline cortices showed higher betweenness centrality, reflecting functional dominance of these brain structures. Third, lower betweenness centrality and lower degree emerged for PFC, suggesting weakened inhibitory control. Overall, network organization showed impairments consistent with neurobiological models of GAD (involving amygdala, PFC, and cingulate cortex) and further pointed to an involvement of temporal regions. Such impairments tended to progress over time and predict anxiety symptoms. A graph-analytic approach represents a powerful approach to deepen our understanding of GAD

Sustained perturbation in functional connectivity induced by cold pain.

BACKGROUND: Functional connectivity (FC) perturbations have been reported in multiple chronic pain phenotypes, but the nature of reported changes varies between cohorts and may relate to the consequences of living with chronic-pain related comorbidities, such as anxiety and depression. Healthy volunteer studies provide opportunities to study the effects of tonic noxious stimulation independently of these sequelae. Connectivity changes in task negative and positive networks, for example, the default mode and salience networks (DMN/SN), respectively, have been described, but how these and other connectivity networks, for example, those governing descending pain control are affected by the presence of tonic, noxious stimulation in healthy, pain-free individuals, remains unknown. METHOD: In 20 healthy volunteers, we assessed FC prior to, during, and following tonic cold painful stimulation in the ventromedial prefrontal cortex (vmPFC), rostral anterior insula (rAI), subgenual anterior cingulate cortex (ACC) and periaqueductal grey (PAG). We also recorded subjectively reported pain using a computerised visual analogue scale. RESULTS: We saw DMN FC changes during painful stimulation and that inter-network connectivity between the rAI with the vmPFC increased during pain, whereas PAG-precuneus FC decreased. Pain-induced FC alterations persisted following noxious stimulation. FC changes related to the magnitude of individuals' subjectively reported pain. CONCLUSIONS: We demonstrate FC changes during and following tonic cold-pain in healthy participants. Similarities between our findings and reports of patients with chronic pain suggest that some FC changes observed in these patients may relate to the presence of an ongoing afferent nociceptive drive. SIGNIFICANCE: How pain-related resting state networks are affected by tonic cold-pain remains unknown. We investigated functional connectivity alterations during and following tonic cold pain in healthy volunteers. Cold pain perturbed the functional connectivity of the ventro-medial prefrontal cortex, anterior insula, and the periacquaductal grey area. These connectivity changes were associated with the magnitude of individuals' reported pain. We suggest that some connectivity changes described in chronic pain patients may be due to an ongoing afferent peripheral drive.This work was funded by a Medical Research Council Experimental Medicine Challenge Grant (MR/N026969/1). MAH, SM, OO and SW are also supported by the NIHR Biomedical Research Centre for Mental Health at the South London and Maudsley NHS Trust. JOM is supported by a Sir Henry Dale Fellowship jointly funded by the Welcome Trust and the Royal Society (grant number 206675/Z/17/Z) and a Medical Research Council (MRC) Centre grant (MR/N026063/1)

The association between pain-induced autonomic reactivity and descending pain control is mediated by the periaqueductal grey.

There is a strict interaction between the autonomic nervous system (ANS) and pain, which might involve descending pain modulatory mechanisms. The periaqueductal grey (PAG) is involved both in descending pain modulation and ANS, but its role in mediating this relationship has not yet been explored. Here, we sought to determine brain regions mediating ANS and descending pain control associations. Thirty participants underwent conditioned pain modulation (CPM) assessments, in which they rated painful pressure stimuli applied to their thumbnail, either alone or with a painful cold contralateral stimulation. Differences in pain ratings between ‘pressure-only’ and ‘pressure + cold’ stimuli provided a measure of descending pain control. In 18 of the 30 participants, structural scans and two functional MRI assessments, one pain-free and one during cold-pain were acquired. Heart rate variability (HRV) was simultaneously recorded. Normalised low-frequency HRV (LF-HRVnu) and the CPM score were negatively correlated; individuals with higher LF-HRVnu during pain reported reductions in pain during CPM. PAG-ventro-medial prefrontal cortex (vmPFC) and PAG-rostral ventromedial medulla (RVM) functional connectivity correlated negatively with the CPM. Importantly, PAG-vmPFC functional connectivity mediated the strength of the LF-HRVnu-CPM association. CPM response magnitude was also negatively correlated with vmPFC GM volume. Our multi-modal approach, using behavioural, physiological and MRI measures, provides important new evidence of interactions between ANS and descending pain mechanisms. ANS dysregulation and dysfunctional descending pain modulation are characteristics of chronic pain. We suggest that further investigation of body-brain interactions in chronic pain patients may catalyse the development of new treatments

Linking Pain Sensation to the Autonomic Nervous System: The Role of the Anterior Cingulate and Periaqueductal Gray Resting-State Networks.

There are bi-directional interactions between the autonomic nervous system (ANS) and pain. This is likely underpinned by a substantial overlap between brain areas of the central autonomic network and areas involved in pain processing and modulation. To date, however, relatively little is known about the neuronal substrates of the ANS-pain association. Here, we acquired resting state fMRI scans in 21 healthy subjects at rest and during tonic noxious cold stimulation. As indicators of autonomic function, we examined how heart rate variability (HRV) frequency measures were influenced by tonic noxious stimulation and how these variables related to participants' pain perception and to brain functional connectivity in regions known to play a role in both ANS regulation and pain perception, namely the right dorsal anterior cingulate cortex (dACC) and periaqueductal gray (PAG). Our findings support a role of the cardiac ANS in brain connectivity during pain, linking functional connections of the dACC and PAG with measurements of low frequency (LF)-HRV. In particular, we identified a three-way relationship between the ANS, cortical brain networks known to underpin pain processing, and participants' subjectively reported pain experiences. LF-HRV both at rest and during pain correlated with functional connectivity between the seed regions and other cortical areas including the right dorsolateral prefrontal cortex (dlPFC), left anterior insula (AI), and the precuneus. Our findings link cardiovascular autonomic parameters to brain activity changes involved in the elaboration of nociceptive information, thus beginning to elucidate underlying brain mechanisms associated with the reciprocal relationship between autonomic and pain-related systems

Goal directed worry rules are associated with distinct patterns of amygdala functional connectivity and vagal modulation during perseverative cognition

Excessive and uncontrollable worry is a defining feature of Generalized Anxiety Disorder (GAD). An important endeavour in the treatment of pathological worry is to understand why some people are unable to stop worrying once they have started. Worry perseveration is associated with a tendency to deploy goal-directed worry rules (known as “as many as can” worry rules; AMA). These require attention to the goal of the worry task and continuation of worry until the aims of the “worry bout” are achieved. This study examined the association between the tendency to use AMA worry rules and neural and autonomic responses to a perseverative cognition induction. To differentiate processes underlying the AMA worry rule use from trait worry, we also examined the relationship between scores on the Penn State Worry Questionnaire (PSWQ) and neural and autonomic responses following the same induction. We used resting-state functional magnetic resonance brain imaging (fMRI) while measuring emotional bodily arousal from heart rate variability (where decreased HRV indicates stress-related parasympathetic withdrawal) in 19 patients with GAD and 21 control participants. Seed-based analyses were conducted to quantify brain changes in functional connectivity (FC) with the amygdala. The tendency to adopt an AMA worry rule was associated with validated measures of worry, anxiety, depression and rumination. AMA worry rule endorsement predicted a stronger decrease in HRV and was positively associated with increased connectivity between right amygdala and locus coeruleus (LC), a brainstem noradrenergic projection nucleus. Higher AMA scores were also associated with increased connectivity between amygdala and rostral superior frontal gyrus. Higher PSWQ scores amplified decreases in FC between right amygdala and subcallosal cortex, bilateral inferior frontal gyrus, middle frontal gyrus, and areas of parietal cortex. Our results identify neural mechanisms underlying the deployment of AMA worry rules. We propose that the relationship between AMA worry rules and increased connectivity between the amygdala and prefrontal cortex (PFC) represents attempts by high worriers to maintain arousal and distress levels in order to feel prepared for future threats. Furthermore, we suggest that neural mechanisms associated with the PSWQ represent effortful inhibitory control during worry. These findings provide unique information about the neurobiological processes that underpin worry perseveration

Neurobiological substrates of cognitive rigidity and autonomic inflexibility in generalized anxiety disorder

Generalized anxiety disorder (GAD) is characterized by difficulties in inhibiting both perseverative thoughts (worry and rumination) and autonomic arousal. We investigated the neurobiological substrates of such abnormal inhibitory processes, hypothesizing aberrant functional coupling within ‘default mode’ (DMN) and autonomic brain networks. Functional imaging and heart rate variability (HRV) data were acquired from GAD patients and controls during performance of three tracking tasks interspersed with a perseverative cognition (PC) induction. After detection of infrequent target stimuli, activity within putative DMN hubs was suppressed, consistent with a redirection of attentional resources from internal to external focus. This magnitude of activity change was attenuated in patients and individuals with higher trait PC, but was predicted by individual differences in HRV. Following the induction of PC in controls, this pattern of neural reactivity became closer to that of GAD patients. Results support, at a neural level, the association between cognitive inflexibility and autonomic rigidity

Effect of parasympathetic stimulation on brain activity during appraisal of fearful expressions

Autonomic nervous system activity is an important component of human emotion. Mental processes influence bodily physiology, which in turn feeds back to influence thoughts and feelings. Afferent cardiovascular signals from arterial baroreceptors in the carotid sinuses are processed within the brain and contribute to this two-way communication with the body. These carotid baroreceptors can be stimulated non-invasively by externally applying focal negative pressure bilaterally to the neck. In an experiment combining functional neuroimaging (fMRI) with carotid stimulation in healthy participants, we tested the hypothesis that manipulating afferent cardiovascular signals alters the central processing of emotional information (fearful and neutral facial expressions). Carotid stimulation, compared with sham stimulation, broadly attenuated activity across cortical and brainstem regions. Modulation of emotional processing was apparent as a significant expression-by-stimulation interaction within left amygdala, where responses during appraisal of fearful faces were selectively reduced by carotid stimulation. Moreover, activity reductions within insula, amygdala, and hippocampus correlated with the degree of stimulation-evoked change in the explicit emotional ratings of fearful faces. Across participants, individual differences in autonomic state (heart rate variability, a proxy measure of autonomic balance toward parasympathetic activity) predicted the extent to which carotid stimulation influenced neural (amygdala) responses during appraisal and subjective rating of fearful faces. Together our results provide mechanistic insight into the visceral component of emotion by identifying the neural substrates mediating cardiovascular influences on the processing of fear signals, potentially implicating central baroreflex mechanisms for anxiolytic treatment targets