Enhanced long-latency somatosensory potentials in major depressive disorder.

Bodily misperceptions are a frequent symptom in major depressive disorder. A reduced ability to deflect attention from somatosensory stimuli may contribute to the generation of unpleasant bodily sensations and co-occur with altered habituation of the brain electric reactions to somatosensory stimuli. The aim of the present study was to explore whether attention-related components of somatosensory evoked potentials (SSEP) and the habituation of these components are altered in major depression. Fifteen patients with major depressive disorder were compared to an age- and gender-matched group of 15 healthy controls. A series of identical, intrusive but not painful electric stimuli were applied to the left index finger for 48 min. Averaged SSEP were computed from multichannel EEG recordings for consecutive recording blocks of the experiment, each block containing 162 stimuli. Based on these data the habituation process of late components of the SSEP was analysed in two latency intervals (50-150, 170-370 ms). Patients showed significantly enhanced reactions throughout the entire experiment. The persistence of enhanced SSEP components throughout the habituation process may be caused by a deficit in reducing the activity of attention-related brain processes concerned with intrusive, yet behaviourally irrelevant, continued stimulation in the state of major depression.

[A rare cause of carpal tunnel syndrome: leprosy. Latency period of decades is possible]. / Seltene Ursache eines Karpaltunnelsyndroms: Lepra. Jahrzehntelange Latenzzeit möglich.

In a 63-year-old German woman with no apparent exposure to leprosy, clinical and histological evidence of tuberculoid leprosy was found. A noteworthy feature of this case is either the very long incubation time of 45 years, or the mode of infection involving an only short encounter in an endemic region. In the event of unclear lesions--on white skin not, typically, hypopigmented, but reddish--accompanied by disordered sensation, we in Europe must also give consideration to the possibility of a sporadic case of leprosy. A particular characteristic of this case was leprous neuritis involving the median nerve which was diagnosed clinically as carpal tunnel syndrome, and scheduled for surgical treatment. Under treatment with dapsone and rifampicin, however, the condition cleared up completely.

Orienting response and frontal midline theta activity: a somatosensory spectral perturbation study.

OBJECTIVE: Brain electric activity in the theta frequency band has been associated with the encoding of new, and the retrieving of previously stored, information. We studied the time course of stimulus-to-stimulus changes of theta activity under repetitive somatosensory stimulation. MATERIALS AND METHODS: Twelve healthy subjects participated in the study. Repetitive electric stimuli, grouped into 48 stimulus trains, were applied to the left index finger. The stimulus trains contained 27 stimuli (0.9 Hz, 2.5 times sensory threshold). Each stimulus train of 30 s was followed by a stimulus-free break of 30 s. This stimulation paradigm allowed the separate estimation of effects for each position of the stimulus in the train and an analysis of stimulus-to-stimulus changes. Multichannel EEG recordings allowed a topographic analysis of the event-related spectral perturbation effects in the theta frequency band. The brain electric novelty response triggered by the stimulus train onset was analyzed by 3 methods: (1) event-related potentials; (2) event-related power spectra for the investigation of spectral perturbation effects on theta activity; and (3) an approach to break down the stimulus-induced theta activity into phase-locked activity and effects on the spontaneous, ongoing theta activity using digital filtering. RESULTS: The main findings are a frontal midline activation in the theta band with the beginning of the stimulus train, which habituates during the subsequent stimulation cycles, as well as evidence that distinct effects of the first stimulus on the ongoing, non-phase-locked, theta activity exist.

Topography and morphology of heart action-related EEG potentials.

Joint ECG and EEG measurements were performed in 22 healthy subjects under standardized laboratory conditions. Averaged EEG potentials were computed using the R-peaks in the ECG as reference events. Spatio-temporal potential patterns of heart action-related EEG activity were obtained from 26 scalp channels. A heart action-related positive potential was found, peaking over the parietal scalp regions. Its independence from the cardiac electrical field, the source of an EEG artifact that may be confounded with heart action-related brain potentials, is demonstrated. The potential reaches its maximum amplitude of about 0.5 microV at a latency of about 500 ms after the R-peak. Its topography, with peak amplitudes at the parietal electrode locations, is different from the topography of potentials observed in the few comparable experimental studies published so far. This suggests the presence of somatosensory-evoked components in heart action-related potentials and indicates that a renewed discussion of the underlying neuronal processes is necessary.

Autonomic reactivity and hormonal secretion in lactate-induced panic attacks.

To compare autonomic and neuroendocrine responses during lactate-induced panic attacks, heart rate variability and cortisol and atrial natriuretic hormone (ANH) levels were measured in patients with panic attacks and in healthy control subjects. In a randomized double-blind design, all subjects received either 10 ml/kg body weight of 0.5 M racemic sodium lactate or normal saline from 1100 to 1120. Spectral analysis of the R-R interval of analog electrocardiograms was performed, and total (0.001-0.45 Hz), low-frequency (0.01-0.05 Hz), midfrequency (0.05-0.15 Hz), and high-frequency power (0.15-0.45 Hz) were computed. Cortisol was measured 12 times in the period from 0900 to 1300, and ANH was measured at 1100, 1120, and 1200 by radioimmunoassay. In both panickers (n = 6) and nonpanickers (n = 8), an infusion of lactate resulted in an acceleration of heart rate, a reduction in total spectral power, and a decrease in the high- and low-frequency components of spectral power. Panickers showed a significant enhancement of the high-frequency power, whereas in nonpanickers, a shift from the mid- and high-frequency toward the low-frequency power emerged. ANH plasma concentrations during lactate infusion in panickers showed a significant increase (115 and 131% at 1120 and 1200, respectively, over concentrations at 1100) in contrast to nonpanickers (20 and 74%, respectively). No group or treatment effects on cortisol secretion emerged, which is in line with former reports. Our study supports preliminary observations that lactate-induced panic attacks enhance the release of ANH, a vasodilatator and inhibitor of sympathetic activity. Hence this hormone not only could inhibit the secretion of the stress hormone cortisol but, in parallel, could also attenuate the sympathetic stimulation to the heart. These inhibitory effects of ANH could explain the so-far-unresolved dissociation between psychopathological alterations and autonomic and endocrine responses of panic attacks.

Cardiac field effects on the EEG.

The electrical field of the heart propagates throughout the entire body and causes changes in the surface potentials on the scalp that are superimposed on brain electric signals. When heart cycle-related EEG averaging is performed, e.g. in order to measure heart cycle-related brain potentials, the effects of the cardiac electrical field result in a high-amplitude artifact in the surface potentials. The topographic and temporal distributions of the cardiac field artifact were measured in 9 normal subjects. In addition, the effects of head-turning on the field were investigated. The electrocardiac artifact is most prominent during the QRS complex and during the T wave of the heart cycle. In both cases it is distinctly asymmetrical in relation to the hemispheres. A comparison of the scalp potentials and a computed vector ECG showed the 3-dimensional nature of the artifact. Non-computational strategies for the handling of the ECG artifact are discussed. A proper separation of the effects of the cardiac electrical field from heart cycle-related brain potentials is a prerequisite for the study of heart cycle-coordinated brain potentials.

[The pathophysiology of anxiety disorders]. / Zur Pathophysiologie von Angstzuständen.

Often anxiety is based upon real or imagined threats and followed by insufficient coping strategies. Some anxiety states are exclusively caused by organic brain diseases, especially by primary tumours of the mesiotemporal lobe. The type of anxiety-disorders depends on the underlying psychodynamic and neurobiological mechanisms. Posttraumatic stress disorder may be regarded as a paradigm, how extraordinary stressful events build up an "engramme of molecular anxiety". Chronification of anxiety states as well as problems in treatment could be understood using this paradigm.

Assessing daily problems with diabetes: a subject-oriented approach to compliance.

The reliability, construct validity, and discriminant validity of a new self-report questionnaire, the Questionnaire on Stress in Diabetic Patients, were assessed in a sample of 617 patients with insulin-dependent diabetes mellitus and non-insulin-dependent diabetes mellitus. The 90-item inventory is designed to assess psychosocial stress associated with problems in daily living with diabetes. One of the intended uses is to identify psychosocial factors hampering patient compliance with the necessary treatment regimen. Values of Cronbach alpha ranged from 0.63 to 0.88. The results provide initial evidence for the reliability and validity of the instrument.

Tonic pain evoked by pulsating heat: temporal summation mechanisms and perceptual qualities.

The properties of a newly developed tonic heat pain model (THPM), which makes use of pulsating contact heat, were investigated in 18 young men. The most important feature of this model is that repetitive heat pulses with an intensity of 1 degree C above the individual pain threshold are employed. This approach was used to tailor the tonic pain stimulation to the individual pain sensitivity. In the first of two experiments, the effects of pulse frequencies ranging from 5 to 30 pulses per minute (ppm) on ratings of pain intensity and pain unpleasantness (visual analogue scales) were examined. At all frequencies, both ratings increased steadily over the 5-min test period. Frequencies of 15 ppm or more appeared to enhance pain intensity throughout the test period compared to the lower frequencies, but did not appear to alter pain unpleasantness. This suggests that only pain intensity is influenced by slow temporal summation and that a sort of frequency threshold exists for this kind of summation. In the second experiment, the THPM was compared to a well-established form of tonic pain stimulation, the cold-pressor test (CPT); visual analogue scales were again used, and in addition the McGill Pain Questionnaire was employed. The CPT appeared to produce stronger tonic pain than the THPM. However, as is typical with tonic pain, both tonic pain models induced relatively higher values on the affective pain dimension than on the sensory pain dimension. The time course of pain was dynamic in the CPT, with an increase followed by a plateau phase, at least in those subjects who could tolerate the CPT for more than 60 sec. In contrast, as in the first experiment, the pain ratings in the THPM were characterized by a slow and steady increase over time. Moreover, there was absolutely no indication of a dichotomy between "pain-sensitive" and "pain-tolerant" individuals in the THPM, although such a dichotomy was evident in the CPT. This implies that the distinction between pain-sensitive and pain-tolerant individuals can be made only with the CPT, and that this distinction represents individual differences in peripheral vascular reactions to cold rather than in pain perception. In conclusion, the THPM appears to produce a stable and predictable temporal pattern of tonic pain with a predominant affective component, and to be suitable for application in the majority of individuals without causing undue discomfort.

Coping with fear of long-term complications in diabetes mellitus: a model clinical program.

Preliminary results are reported on the efficacy of a behaviorally oriented group therapy (n = 17) intended to improve coping with fear of long-term complications in patients with diabetes mellitus. Treatment consisted of exposure in imagination, relaxation training and analysis of dysfunctional health beliefs. Pre-, posttreatment and 3-month follow-up measure showed significant improvements regarding fear, acceptance of chronic disease and work. The usefulness of such a treatment program and the necessarity for further research is discussed.

Pain sensitivity in recovered anorexics, restrained and unrestrained eaters.

The heat pain threshold and local skin temperature were assessed in 23 former anorexic in-patients with an 'intermediate' (N = 9) or 'good' outcome (N = 14) and in 21 restrained and 20 unrestrained eaters. All subjects were female. The group means of the pain thresholds did not differ significantly from each other, suggesting that the homogeneous increase in pain thresholds we had previously observed in acutely ill eating disorder patients is state dependent. However, a sizeable percentage of the restrained eaters (29%) had pain thresholds clearly above the normal range. Thus it may well be that restrained eating carries a risk of reducing pain sensitivity. Pain threshold and skin temperature correlated significantly (r = -0.63) only in the group of patients with an intermediate outcome, a finding resembling that obtained in acute anorexics. This suggests that peripheral thermoregulation and pain sensitivity are linked in the acute and moderately improved phases of anorexia nervosa.

Theoretical and empirical considerations on the relation between 'body image', body scheme and somatosensation.

The authors first discuss possible interactions between the hitherto neglected neurophysiological and neuropsychological factors and the traditionally accepted cognitive and affective factors in 'body image' formation. They then report on a study of the relation between body size perception (video distortion technique, image marking procedure, kinaesthetic size estimation apparatus) and somatosensation (thermal, pain and vibration thresholds) in young women. Included in the study were questionnaires on eating behaviour and motivation, body attitude or body satisfaction, and depressive mood and thoughts. Neither the somatosensory nor the questionnaire variables explained the difference between 'overestimators' and 'underestimators' of body size. However, these variables did explain the difference between 'good perceivers' and 'poor perceivers' (degree of deviation from actual body size) in the video distortion technique, with a somewhat larger contribution by the somatosensory variables. The latter finding, although clearly preliminary, should stimulate further investigations of the relationship between somatosensory variables and body size perception.

The role of body size in somatosensory testing.

To try to replicate our earlier findings of body size influences in somatosensory testing we measured thresholds of heat pain, warmth, cold and vibration in 66 young, normal-weight women. Our assumption was that true body measure effects have to be demonstrable even in a sample limited with regard to age and sex and without extreme body size variation (which may be linked to pathology). In the present sample, body size (a linear combination of height and weight) did not have a very strong relation with any of the somatosensory thresholds (slightly stronger for the warmth and cold thresholds than for the heat pain and vibration thresholds). Hence, we could not fully replicate our earlier findings of marked body size effects on warmth and cold thresholds obtained in a sample without such limits. A measure of the body fat content seemed to have some explanatory power, but only for the vibration thresholds. We conclude that body measures, age and sex may be confounded in a way that cannot always be sorted out by a posteriori analyses and should therefore be treated a priori as independent variables for purposes such as establishing normal values in somatosensory testing.

Body size perception and body satisfaction in restrained and unrestrained eaters.

In 21 restrained and 20 unrestrained eaters body size perception was measured using the video distortion technique (VDT), the image marking procedure (IMP) and the kinesthetic size estimating apparatus (KSEA). Body satisfaction was assessed by questionnaires (Body Shape Questionnaire, Dieting scale of the Eating Attitudes Test). Restrained eaters showed no systematic over- or underestimation of the body size but less perceptual accuracy (in VDT and KSEA). Furthermore, they were clearly more dissatisfied with their bodies than unrestrained eaters. Both findings were unrelated to each other. In both groups depressive mood or thoughts seemed to be associated with body dissatisfaction but not with body size misperception. Objective body measures (body mass index, body fat content) were not related to either body size perception or body satisfaction. The findings suggest that a perceptual uncertainty in regard to body size (either for visual or for somatosensory aspects) has already developed in restrained eaters, which may constitute a predisposition for more overt forms of body size misperception as found in eating disorder patients.

Disturbances of C-fibre-mediated sensibility in lumbosacral disc disease.

In nine patients with chronic lumbosacral disc disease and radicular symptoms clearly restricted to one leg, C-fibre-mediated sensibility was measured by determination of the thresholds for heat pain and warmth on the foot, ipsi- and contralaterally to the nerve root compression. The thresholds were compared with the values for 19 healthy subjects. In the patients the warmth threshold was increased in the ipsilateral dermatome and normal in the contralateral dermatome. In contrast, the heat pain threshold was near normal ipsilaterally but was clearly decreased contralaterally. These findings are discussed with respect to a possible pain sensitisation resulting from nerve root compression.

[Compliance problems in type I diabetic patients]. / Complianceprobleme bei Typ-I-Diabetikern.

Using a newly developed interview concept, 49 type I diabetics were questions about "obstacles to compliance". The patients were asked to identify, in nine different areas of life, any common concrete obstacles to compliance with self-treatment in terms of dietary measures, injections and self monitoring. Emotional barriers and the structuring of everyday activities proved to be of particular importance for compliance with dietary measures, and aspects of the doctor-patient relationship for insulin injection. The results obtained indicate a need both for abandoning the classical term of compliance, and for the use of psychological measures to support the instruction of diabetics.

[Cardiovascular factors of cardiac phobia--a field study]. / Kardiovaskuläre Faktoren der Herzphobie--Eine Felduntersuchung.

The interaction between psychological and physiological factors was studied with a field approach in 28 patients with cardiac phobia and 20 healthy controls. A 24-hour ambulatory ECG was recorded, and the subjects were instructed to report their activities and any cardiac perception during this period. Additionally, psychological tests assessing well-being (Bf-S), bodily complaints (B-L), and state and trait anxiety (Stai-S and Stai-T) were administered. The groups did not differ in the mean cardiovascular parameters, however patients with cardiac phobia and healthy controls showed clear differences in the strength and direction of correlations between psychological and physiological variables. The incidence of cardiac perceptions was about the same in both groups, but only patients with cardiac phobia attributed the perceptions to an internal stimulus and associated the perceptions with anxiety. Depending on the anxiety elicited by the cardiac perceptions, the patients with cardiac phobia showed heart rate accelerations, which did not occur in healthy controls. This study confirms a psychosomatic process between psychological and physiological variables, which seems to be able to explain the development and maintenance of cardiac phobia.