In a double-blind, placebo-controlled trial, the effect of 75 mg of a slow-release formulation of amitriptyline on the clinical severity of chronic tension-type headache and on headache-associated neurophysiological parameters (EMG activity, exteroceptive suppression of temporal muscle activity, contingent negative variation (CNV) and experimental pain sensitivity) was investigated. All of the patients treated had a history of headaches of many years' standing and many of them had failed attempts at treatment. In the amitriptyline group, a significant reduction in daily headache duration was already found in the 3rd week of treatment, while in the placebo group no significant changes in headache duration were to be seen. In week 6 the amitriptyline group had a significantly shorter daily duration of headache than did the placebo group. Treatment did not result in any significant effects on EMG recordings of pericranial muscle activity either during relaxation or contraction, on exteroceptive suppression of the temporal muscle and on CNV. The sensitivity to suprathreshold experimental pain, however, was significantly reduced. The data show a statistically relevant reduction of daily headache duration. However, they also show that amitriptyline can only partly alleviate chronic headaches but cannot cure them.

In the present study the question was addressed whether sensitivity to experimental pain stimuli differs between families, which are previously characterized by the degree of cold tolerance (very insensitive or very sensitive) of one family member. A total of 232 healthy medical students were screened for cold pain tolerance employing a cold pressor test. Subsequently 50 of them were investigated in detail under laboratory conditions. The water temperature was 1 degrees C, the maximum time in water 3 min, cold pain was rated on a 101 step numerical rating scale every 10s. Two of the most cold pain sensitive (shortest time in ice water) and insensitive (lowest ratings) students were selected and as many as possible of their family members were recruited. In all of them cold pressor test, pinprick pain threshold, pressure pain threshold, skin temperature, hospital anxiety and depression scale and COMT val158met polymorphism (with the exception of three individuals) were assessed. Analysis (ANOVA) revealed that the cold pressor results of the students predicted the mean ratings (p<0.04) and the time in ice water (p<0.03) of their own families. Furthermore, pinprick pain threshold (p<0.002) and to a lesser extent pressure pain thresholds (p<0.03) were significantly related to cold pain tolerance. The other variables, including the COMT polymorphism, were not related to cold pain tolerance in our study. In conclusion our results suggest that cold pain tolerance may be at least partially inherited. Genetic or environmental factors might explain family clustering of cold pain sensitivity.

Analgesic tolerance to opioids has been described in both experimental and clinical conditions and may limit the clinical utility of these drugs. We have previously shown that systemic gabapentin (GBP), a non-opioid drug, prevents and reverses tolerance to systemic morphine in the rat. In this study, we investigated the effect of intrathecal GBP on spinal morphine tolerance. Studied rats were given 7 days of intrathecal injections with saline (10 microL), GBP (300 microg), morphine (15 microg), or a GBP-morphine combination, and analgesic testing using tail-flick and paw-pressure tests was conducted before and 30 min after the drug injection. On Day 8, an antinociceptive dose-response curve was constructed and the 50% effective dose (ED(50)) values for morphine (given alone) were calculated for each study group. Coinjection of GBP with morphine blocked the development of tolerance, as shown by the preservation of morphine analgesia over 7 days as well as by a concomitant decrease in ED(50) values on Day 8, as compared with the morphine-alone group. Although additive analgesia over Days 1-7 cannot be ruled out, ED(50) reductions in the GBP-morphine combination group indeed suggest some suppression of tolerance. These data support previous evidence that GBP prevents opioid tolerance and, more specifically, indicate that intrathecal GBP prevents the development of spinal opioid tolerance. Future studies are required to examine the respective roles of supraspinal and peripheral sites of GBP-morphine interaction and to investigate the mechanisms underlying the action of GBP on opioid tolerance.

Background It is well known that low platelet count on admission to intensive care units (ICU) is associated with increased mortality. However, it is unknown whether prothrombin time (PT‐INR) and activated partial thromboplastin time (APTT) on admission correlate with mortality and organ failure. Therefore, the aim of this study was to investigate whether PT‐INR and APTT at admission can predict outcome in the critically ill patient after adjusting for severity of illness measured with Simplified Acute Physiology Score 3 (SAPS 3). Materials and Methods Data were retrospectively collected. APTT and PT‐INR taken on admission and SAPS 3 score were independent variables in all regression analyses. Survival analysis was done with Cox regression. Organ failure was reported as days alive and free (DAF) of vasopressors and invasive ventilation, need of continuous renal replacement therapy (CRRT) and Acute Kidney Injury Network creatinine score (AKIN‐crea). Results A total of 3585 ICU patients were included. Prolonged APTT correlated with mortality with 95% confidence interval (CI) of hazard ratio 1.001‐1.010. Prolonged APTT also correlated with DAF vasopressor, CRRT and AKIN‐crea with 95% CI of odds ratio (OR) 1.009‐1.034, 1.016‐1.037 and 1.009‐1.028, respectively. Increased PT‐INR correlated with DAF vasopressor and DAF ventilator with 95% CI of OR 1.112‐2.014 and 1.135‐1.847, respectively. Conclusions Activated partial thromboplastin time prolongation was associated with mortality and all morbidity outcomes except the DAF ventilator. PT‐INR increase at admission was associated with DAF vasopressor and DAF ventilator. APTT and PT‐INR at admission correlate with morbidity, which is not accounted for in the SAPS 3 model.