[Pain therapy in addicted patients]

Each individual is entitled to an adequate and sufficient pain therapy. However, only a few studies have examined the peculiarities of pain management in drug-dependent or formerly addicted patients. Any addiction is disadvantageous for a successful pain therapy, since some of the prescribed drugs may themselves cause addiction. Drug-dependent patients are often tolerant to opioids. Additionally, there is a risk of iatrogenic pain becoming chronic due to disregard for already known risk factors and comorbidities. However, a history of addiction should not prevent sufficient pain therapy, especially since there is no risk of addiction when the pain therapy employed is adequate for the pathophysiology involved. There are adequate pain therapies for addicted patients. The best results are achieved by taking into account the physiological and psychological peculiarities of drug-dependent patients. Importantly, this should be combined with a variety of different, optimized, multimodal therapeutic regimes, as well as with an interdisciplinary approach.

Specific cue reactivity on computer game-related cues in excessive gamers

It has been posited that excessive computer game playing behavior, referred to as computer game addiction, meets criteria that have been internationally established to define drug addiction. Nevertheless, there have been no psychophysiological investigations of the underlying mechanisms available to support the characterization of excessive computer gaming as behavioral addiction. To investigate whether excessive computer gaming parallels learning processes in development and maintenance (which are assumed to underlie drug addiction), the authors obtained a psychophysiological assessment of the (learned) emotional processing of computer game-relevant and -irrelevant cues. For this purpose, electroencephalographic recordings in excessive and casual computer game players were conducted. Significant between-group differences in event-related potentials evoked by computer game related-cues were found at parietal regions and point to an increased emotional processing of these cues in excessive pathological players compared with casual players. These results are in concordance with the suggestion that addiction is characterized and maintained through sensitization of the mesolimbic dopaminergic system along with incentive salience of specific addiction-associated cues.

Verhaltenssucht

Until recently knowledge was limited with respect to clinically relevant excessive reward-seeking behaviour such as pathological gambling, excessive shopping, and excessive working which meet diagnostic criteria of dependent behaviour. To date there is no consistent concept for diagnosis or treatment of excessive reward-seeking behaviour, and its classification is uncertain. However, the high number of subjects seeking treatment emphasises the importance of a clear conceptualisation of the so-called behavioural addictions and their successful treatment. Excessive reward-seeking behaviour may be used to regulate negative emotions. We suggest that, comparable to drug addiction, excessive reward-seeking behaviour can alleviate negative mood states and may be used as an (inadequate) stress coping strategy at the expense of active coping strategies. In the course of a pathological development, behavioural addiction may become the only available behavioural resource to cope with challenging developmental steps or social stress factors such as loneliness or anxiety.

Excessive Computer Game Playing: Evidence for Addiction and Aggression?

Computer games have become an ever-increasing part of many adolescents' day-to-day lives. Coupled with this phenomenon, reports of excessive gaming (computer game playing) denominated as "computer/video game addiction" have been discussed in the popular press as well as in recent scientific research. The aim of the present study was the investigation of the addictive potential of gaming as well as the relationship between excessive gaming and aggressive attitudes and behavior. A sample comprising of 7069 gamers answered two questionnaires online. Data revealed that 11.9% of participants (840 gamers) fulfilled diagnostic criteria of addiction concerning their gaming behavior, while there is only weak evidence for the assumption that aggressive behavior is interrelated with excessive gaming in general. Results of this study contribute to the assumption that also playing games without monetary reward meets criteria of addiction. Hence, an addictive potential of gaming should be taken into consideration regarding prevention and intervention.

Reizinduziertes Alkoholverlangen

If there is no further intervention, relapse rates in detoxified alcoholics are high, up to 85%, even after complete remission of bodily withdrawal symptoms. It has been suggested that one relevant mechanism contributing to the relapse risk is the exposure to stimuli (cues) that have regularly been associated with alcohol intake. Such stimuli can become conditioned cues that elicit alcohol craving and intake as conditioned responses. Current brain imaging studies indicate that dysfunction of dopaminergic, glutamatergic, and opioidergic neurotransmission in the brain reward system (ventral striatum including the nucleus accumbens) is associated with alcohol craving and brain activation elicited by alcohol-associated pictures. These findings point to specific indications for psychotherapeutic and additive pharmacological treatment options.

[Pathological gambling. An empirical study of the desire for addictive substances]

Drug craving, the irresistible urge for drug intake, is being discussed as a central construct for the explanation of addictive behaviour and for relapses so far only in substance-related addiction. Based on learning models for the maintenance of addiction, in this study, cue-induced craving and psychological variables that influence craving were investigated in subjects with excessive rewarding behaviour such as pathological gambling. Based on the cue-reactivity paradigm, pathological gamblers and healthy controls were exposed to gambling and other cues. Emotional processing of the gambling cues, cue-induced craving, and the influence on craving of depression, anxiety, and stress-coping strategies were investigated. The results demonstrate disorder-specific processing of cues in pathological gamblers, even after abstinence for more than a year. In addition, craving is influenced by psychological disabilities. Data are discussed with respect to comparable data in studies about substance-related addicts.

[Phantom limb pain: aspects of neuroplasticity and intervention]

Phantom-limb pain is a common sequel of amputation, occurring in up to 80 % of the amputee population. It must be differentiated from non-painful phantom phenomena, residual-limb pain, and non-painful residual-limb phenomena. A comprehensive model of phantom-limb pain is presented that assigns a major role to pain occurring before the amputation and to central as well as peripheral changes related to it. Special emphasis is put on the role of cortical reorganization in the development of phantom limb pain. Finally, new approaches to the prevention and treatment of phantom limb pain are presented that have a positive influence on phantom limb pain by preventing or reversing cortical reorganization.

Remote activation of referred phantom sensation and cortical reorganization in human upper extremity amputees

Phantom limb sensation, whether painful or not, frequently occurs after peripheral nerve lesions. It can be elicited by stimulating body parts adjacent to the amputation site (referred to as phantom sensation) and it is often similar in quality to the stimulation at the remote site. The present study induced referred phantom sensations in two upper limb amputees. Neuroelectric source imaging (ESI) as well as functional magnetic resonance imaging (fMRI) was used to assess reorganization in primary somatosensory cortex (SI). Whereas recent studies found mislocalization of sensation related to stimulation mainly in regions adjacent and ipsilateral to the amputation site, we report here the elicitation of phantom sensation in the arm by stimulation in the lower body part both ipsi- and contralateral to the amputation in two arm amputees. The fMRI evaluation of one patient showed no shift in the location of the foot whereas ESI revealed major reorganization of the mouth region in primary somatosensory cortex in both patients. These data suggest that cortical structures other than SI might be contributing to the phenomenon of referred sensation. Candidate structures are the thalamus, secondary somatosensory cortex, posterior parietal cortex and prefrontal cortex.

Development of alcohol-associated cues and cue-induced brain activation in alcoholics

The objective of this study was to develop new standardized alcohol-associated cues and assess their effects on brain activation with functional magnetic resonance imaging (fMRI). Pictures of alcoholic and neutral beverages and affectively neutral pictures were presented to 44 abstinent alcoholics and 37 age-matched healthy control subjects. We assessed the skin conductance response, and the elicited arousal and valence. Alcoholics and control subjects did not differ in arousal, valence or skin conductance response evoked by alcohol-associated and affectively neutral stimuli, while nonalcoholic beverages were rated as more unpleasant and arousing by alcoholics compared with control subjects. In the fMRI pilot study, alcohol and abstract pictures were presented to six abstinent alcoholics and induced a significant activation of brain areas associated with visual emotional processes such as the fusiform gyrus, parts of the brain reward system (basal ganglia and orbitofrontal gyrus) and further brain regions in the frontal and parietal cortices associated with the attention network. These observations suggest that standardized pictures of alcoholic beverages can be used to assess brain circuits involved in the processing and evaluation of alcohol cues.

[The phantom and stump phenomena interview (PSPI)]

RESEARCH QUESTION

A structured German-language interview was developed for the assessment of painful and non-painful phantom and stump phenomena after amputation. The aim was a thorough assessment of the quality, quantity and time course of these phenomena, which is of scientific as well as therapeutic relevance.

METHODS

Each phenomenon was assessed using visual analogue scales as well as qualitative descriptors adapted from the McGill Pain Inventory and from literature reports. The factor structure and psychometric properties of the interview were evaluated in a sample of 139 upper and lower limb amputees. Test-retest coefficients were obtained in a subset of 20 amputees.

RESULTS

As expected, all pain-related scales showed a two-dimensional internal structure with the factors "affective pain" and "sensory pain". For the non-painful phantom sensations, three factors "general/kinesthetic phantom sensations", "phantom movements" and "paresthesias" were obtained, while for non-painful stump sensations only one general factor emerged. The internal consistency was high with respect to the pain-related scales and was still satisfying for the scales that cover nonpainful phantom and stump phenomena. All scales have sufficient validity. Test-retest coefficients suggest a satisfactory stability of all scales that assess present phenomena, while the stability of the retrospective scales is markedly lower and in some cases insufficient.

CONCLUSIONS

The phantom and stump phenomena interview is a highly reliable and valid instrument to assess present perceptual phenomena after amputation. Only the included retrospective scales apparently show low stability scores over time. This raises the more general question of the validity of retrospective pain reports.

The relationship of perceptual phenomena and cortical reorganization in upper extremity amputees

In this study 16 unilateral upper extremity amputees participated in a comprehensive psychophysiological examination that included the assessment of painful and non-painful phantom and stump sensations, thermal and electric perception as well as two-point discrimination thresholds, the detailed analysis of referred sensation and the measurement of reorganizational changes in primary somatosensory cortex using neuroelectric source imaging. Reorganization of the primary somatosensory cortex was associated with increased habitual phantom limb pain, telescoping, non-painful stump sensations and painful referred sensation induced by painful stimulation. It was unrelated to non-painful phantom sensations, non-painful referred sensation elicited by painful or non-painful stimulation, painful referred sensation elicited by non-painful stimulation, perception thresholds and stump pain. These data substantiate the hypothesis that painful and non-painful phantom phenomena are mediated by different neural substrates.

Perceptual phenomena after unilateral arm amputation: a pre-post-surgical comparison

Painful and non-painful phantom phenomena occur frequently after amputations but are rarely investigated in the perioperative stage. The goal of the present study was the assessment of phantom phenomena, pain and changes in primary somatosensory cortex prior to and after upper limb amputation. Two patients who suffered from metastatic carcinoma were examined 2 days prior to and 7 days after the amputation of an arm using comprehensive psychometric assessments and neuroelectric source imaging. Both patients reported phantom limb pain that was similar to their pre-amputation pain. In one patient, reorganization of the mouth area into the deafferented hand area took place immediately after the amputation. In the other patient reorganization had occurred prior to the amputation possibly related to non-use of the arm several years prior to the amputation.

Standardized stimuli to assess drug craving and drug memory in addicts

Due to conditioning processes, originally neutral stimuli become drug-associated cues and can initiate drug craving. Standardized stimuli are required to assess stimulus-induced activation of drug memory and craving in brain imaging and neurophysiology studies. We developed substance-specific visual and olfactory stimuli for alcohol, tobacco, opiate and cannabis abuse and tested them in subjects with the respective addiction and in healthy volunteers. Stimulus-related drug craving differed significantly between the diagnostic groups and indicated that the stimuli are suitable for craving studies.