Alterations in cerebrospinal fluid concentrations of somatostatin-like immunoreactivity in chronic pain patients.

Concentrations of somatostatin-like immunoreactivity in cerebrospinal fluid were significantly reduced in chronic pain patients compared to control patients without chronic pain. This difference was not influenced by demographic or clinical characteristics. Somatostatin has been shown to be a neurotransmitter in animal nociception; pharmacologic doses of this substance have moderated human pain. Our findings provide evidence that somatostatin may be involved in the pathogenesis of the chronic pain state.

CSF monoamine metabolites in chronic pain.

Metabolites of selected neurotransmitters (5-HIAA, HVA and DOPAC) and beta-endorphin were measured in the CSF of 39 chronic pain patients and compared to controls. Twelve of the pain patients also fulfilled criteria for major depression. The concentration of 5-HIAA was increased in female but not male pain patients; there was no significant difference in the CSF concentrations of HVA and DOPAC. The presence of depression did not influence the concentrations of neurotransmitters. No correlation was found between the concentrations of monoamine metabolites and beta-endorphin. However, there was a positive correlation between 5-HIAA and HVA in controls and chronic pain patients without depression but not in depressed patients. It is concluded: chronic pain states are associated with elevation of CSF 5-HIAA in female patients; depression abolishes a positive correlation between 5-HIAA and HVA.

Chronic pain and depression. IV. DST as a discriminator between chronic pain and depression.

In an attempt to clarify the relationship between chronic pain and depression, the authors studied the plasma cortisol response to dexamethasone in a group of 73 consecutive chronic low back pain patients admitted to a pain unit and 34 consecutive patients admitted to an affective disorders unit with the principal diagnosis of primary major depression. Patients with chronic pain were evaluated as to the presence or absence of major depression and patients with primary major depression were evaluated as to the presence or absence of pain complaints as part of their presenting symptomatology. Chronic pain patients with major depression differed significantly from chronic pain patients without major depression (3.4 +/- 3.33 micrograms/dl versus 1.6 +/- 0.9 micrograms/dl, P less than 0.05). Chronic pain patients with major depression also differed from patients with primary major depression with pain complaints (3.4 +/- 3.3 micrograms/dl versus 10.7 +/- 8 micrograms/dl, P less than 0.0005). The values given are post-dexamethasone plasma cortisol levels. Patients having primary major depression with pain complaints do not significantly differ from patients having primary major depression without pain complaints. The dexamethasone suppression test may be a useful method in discriminating those patients with chronic pain versus those with primary major depression, chronic pain patients with major depression versus those with primary major depression and chronic pain patients with major depression versus those with chronic pain and no depression.

Preliminary study of thyrotrophin releasing hormone stimulation test in chronic low back pain patients.

Chronic pain has been considered as a variant of depression or as a masked depression. In an attempt to unravel the complex relationship between chronic pain and depression, we administered the TRH stimulation test to a uniform group of chronic pain patients classified into those with and without major depression using DSM-III criteria. Eighteen percent showed blunting of TSH response to TRH. There was no significant difference between the two groups.

Chronic pain and depression. III. Family history study of depression and alcoholism in chronic low back pain patients.

In an attempt to unravel the relationship between chronic pain and depression, the authors studied the incidence of depression, alcoholism, and chronic pain in first degree relatives of 100 chronic pain patients with and without depression. A higher incidence of major depression was found in first degree relatives of those patients with depression than those without depression. Familial incidence of alcohol dependence was similar in both groups of patients. These findings confirm an earlier report and raise questions about the notion of considering chronic pain simply as a variant of depression and suggest the possibility that the occurrence of major depression in chronic back pain might be related to genetic vulnerability to depression in these patients.

Long-term use of narcotic/antidepressant medication in the management of phantom limb pain.

The successful management of 5 consecutive patients with intractable phantom limb pain is described. The main therapy is a combination of a narcotic and antidepressant. Medication remained effective during the average observation time of 22 months. There were no signs of habituation or addiction. We conclude that narcotics can be safely and successfully utilized for long-term management of phantom limb pain.

Chronic pain and depression. I. Classification of depression in chronic low back pain patients.

An association between chronic pain and depression has been recognized for a long time. However, the exact nature of this relationship remains unclear. The authors studied 71 patients for affective disorders and schizophrenia-lifetime version (SADS-L). Based on the interviews, we were able to identify 31 patients with major depression, 8 patients with minor depression and 18 with intermittent depressive disorder as defined by Research Diagnostic Criteria. Item analysis using the Hamilton Depression Rating Scale and the Montgomery-Asberg Depression Rating Scale showed that the items did not discriminate in patients with major depression the presence of organic findings. However, most of the items significantly discriminated between the various types of depression and patients without depression. The occurrence of clearly defined depression points to several avenues of research aimed at clarifying the incidence etiology and treatment of depression in these patients.

Chronic pain and depression. II. Symptoms of anxiety in chronic low back pain patients and their relationship to subtypes of depression.

The relationship between anxiety and chronic pain has been poorly studied. The authors studied the occurrence of symptoms of anxiety in chronic low back pain patients. Anxious mood and other symptoms of anxiety were commonly seen in patients with chronic low back pain. Symptoms of anxiety were more common in patients with depression, especially those with major depression. Anxious mood, tension and general somatic symptoms of the sensory type were more common than any other type of anxiety symptoms. The authors discuss the potential role of anxiety in chronic pain patients.

The dexamethasone suppression test as a biologic marker of depression in chronic pain.

The relationship between chronic pain and depression has become enmeshed in the literature. In an attempt to unravel the relationship between chronic pain and depression, the authors studied a uniform group of 80 chronic back pain patients with and without depression using the dexamethasone suppression test (DST). The DST examines the hypothalamic response to an exogenously administered steroid (dexamethasone) challenge. In normal subjects and patients without major depression, the dexamethasone suppresses the release of cortisol from the adrenal glands. In 40% of patients with major depression, there is an early escape of cortisol from dexamethasone suppression. We found that 40% of patients with a DSM-III major depression (dysphoric mood, appetite and sleep changes, loss of energy and interest, decreased concentration, suicidal ideation, and feelings of self-reproach) were non-suppressors and none of the patients without major depression showed this abnormality. These findings suggest that the concept of chronic pain as a variant of depression might be an oversimplification.

A study of psychophysical scaling in chronic pain patients.

Chronic pain patients were asked to psychophysically scale two sets of word descriptors (intensity and unpleasantness) using a crossmodality matching procedure with line length and numerical estimates. In 22 patients (group I) descriptor scaling was performed once, in another 20 patients (group II) the procedure was repeated 3 times. 72.7% of patients in group I obtained a correlation of 0.9 or higher when scaling intensity descriptors, but only 18.2% obtained this correlation when scaling unpleasantness words. In group II, an average of 85% of patients reliably scaled intensity words, but only 50% could do so for the unpleasantness descriptors. Patients who reliably judged unpleasantness descriptors generally exhibited a higher level of psychological distress (SCL-90 R). Numerical estimates assigned by patients to individual word descriptors showed a smaller range than obtained from experimental pain studies. There was unequal spacing of values of adjacent descriptors with clustering of words in the low and high ends of the continuum and large gaps in midrange. Results indicate that chronic pain patients in general show a higher incidence of impairment in rendering proportional judgments than a healthy population. In addition, they are more likely to judge pain reliably on an intensity than on an unpleasantness dimension. The difference in performance between scales persists in spite of training and could not be explained by medical history, drug intake, or demographic characteristics. Patients who are unable to render reliable judgments are easily identified. For optimal clinical use words clustering close together should be combined and additional words should be added describing midrange intensities. Conversely, psychophysical scaling techniques may be used to calibrate category or analogue scales of pain.