Fatal Fever of Unknown Origin in Acute Cervical Spinal Cord Injury: Five Cases

Background/Objective: Patients with traumatic upper thoracic and cervical spinal cord injuries are at increased risk for the development of autonomic dysfunction, including thermodysregulation. Thermoregulation is identified as an autonomic function, although the exact mechanisms of thermodysregulation have not been completely recognized. Quad fever is a hyperthermic thermoregulatory disorder that occurs in people with acute cervical and upper thoracic spinal cord injuries. First described in 1982, it has not been widely discussed in the literature.

Methods: Case reports of 5 patients with cervical spinal cord injury (SCI).

Results: Five of 18 patients (28%) with acute cervical SCI who were admitted during a 1-year period had fatal complications caused by persistent hyperthermia of unknown origin.

Conclusions: Patients with acute traumatic cervical and upper thoracic SCI are at risk for thermoregulatory dysfunction. Changes in the hypothalamic axis may be implicated, especially in the light of modification in hypothalamic afferent nerves, but this hypothesis has not yet been explored. Thermodysregulation may be an early sign of autonomic dysfunction. A comprehensive guideline is needed for the management of elevated body temperature in critically ill patients with cervical SCI, because this condition may be fatal.     

Tattoos do not affect exercise-induced localised sweat rate or sodium concentration

ObjectivesSkin tattoos have been shown to reduce localised sweat rate and increase sweat sodium concentration ([Na⁺]) when sweating is artificially stimulated. This study investigated whether similar responses are observed with exercise-induced sweating.DesignUnblinded, within-participant control, single trial.MethodsTwenty-two healthy individuals (25.1 ± 4.8 y (Mean ± SD), 14 males) with a unilateral tattoo ≥11.4 cm² in size, ≥2 months in age, and shaded ≥50% participated in this investigation. Participants undertook 20 min of intermittent cycling (4 × 5 min intervals) on a stationary ergometer in a controlled environment (24.6 ± 1.1 °C; 64 ± 6% RH). Resultant sweat was collected into absorbent patches applied at two pairs of contralateral skin sites (pair 1: Tattoo vs. Non-Tattoo; pair 2: Control 1 vs. Control 2 (both non-tattooed)), for determination of sweat rate and sweat [Na⁺]. Paired samples t-tests were used to determine differences between contralateral sites.ResultsTattoo vs. Non-Tattoo: Neither sweat rate (Mean ± SD: 0.92 ± 0.37 vs. 0.94 ± 0.43 mg·cm⁻²·min⁻¹, respectively; p = 0.693) nor sweat [Na⁺] (Median(IQR): 37(32–52) vs. 37(31–45) mM·L⁻¹, respectively; p = 0.827) differed. Control 1 vs. Control 2: Neither sweat rate (Mean±SD: 1.19 ± 0.53 vs. 1.19 ± 0.53 mg·cm⁻²·min⁻¹, respectively; p = 0.917) nor sweat [Na⁺] (Median(IQR): 29(26–41) vs. 31(25–43) mM·L⁻¹, respectively; p = 0.147) differed. The non-significant differences for sweat rate and [Na⁺] between Tattoo vs. Non-Tattoo were inside the range of the within participant variability (sweat rate CVi = 5.4%; sweat [Na⁺] CVi = 4.4%).ConclusionsSkin tattoos do not appear to alter the rate or [Na⁺] of exercise-induced sweating. The influence of skin tattoos on localised sweat responses may have previously been over-estimated.     

Patterns of surface temperatures in two mole-rats (Bathyergidae) with different social systems as revealed by IR-thermography

Furred subterranean mammals face the problem of dissipating heat to the environment because high humidity and absence of air flow in sealed belowground tunnels constrain heat loss from body by convection and evaporation. In order to detect body areas responsible for heat loss, surface temperatures in two species of African mole-rats were measured at different ambient air temperatures by infrared thermography. Fur characteristics were also evaluated. Thinner pelage of the ventrum, its moderate temperature and large size suggest that ventral side of the body is the main thermal avenue for heat loss in both species. Interspecific differences could be explained by different fur characteristics connected with social thermoregulation. Compared to the social Fukomys mechowii, the solitary Heliophobius argenteocinereus has denser and longer fur on most of its body; its surface temperature was thus lower than in F. mechowii at lowered ambient temperatures. On the other hand, the denser and longer hair cover in H. argenteocinereus impedes heat dissipation at highest ambient temperatures (and probably also during digging activity) resulting in increase of core body temperature. H. argenteocinereus seems to be more sensitive to overheating than F. mechowii. At lower air temperatures, the social species may uses huddling to combat hypothermia.     

Exercise-induced hyperthermia in childhood: a case report and pilot study

Hyperthermia is characterized by an increase of body core temperature due to exogenous heat exposure and/or endogenous heat production. Contrary to fever the hypothalamic-controlled temperature set point remains unchanged.
Aim: To demonstrate that exercise-induced hyperthermia is a common phenomenon in childhood.
Case: We describe a 5-year-old boy, who attended our outpatient clinic with a 6-month observation period of exercise-induced hyperthermia with rectal temperatures up to 39.0°C. Characteristically temperature dropped to normal values after cessation of exercise.
Method: In eight children aged 5–8, tympanic and rectal temperatures were measured before and after exercise.
Results: The rectal temperature increases frequently after exercise (p < 0.001), whereas tympanic temperature did not (p = 0.2).
Conclusion:  Benign hyperthermia should be considered in children with increased body temperature of unknown sources. The site of temperature measurement might be critical in the identification of this condition.     

Effects of alcohol on autonomic responses and thermal sensation during cold exposure in humans

We investigated the effects of alcohol on thermoregulatory responses and thermal sensations during cold exposure in humans. Eight healthy men (mean age 22.3 ± 0.7 year) participated in this study. Experiments were conducted twice for each subject at a room temperature of 18°C. After a 30-min resting period, the subject drank either 15% alcohol at a dose of 0.36 g/kg body weight (alcohol session) or an equal volume of distilled water (control session), and remained in a sitting position for another 60 min. Mean skin temperature continued to decrease and was similar in control and alcohol sessions. Metabolic rate was lower in the alcohol session, but the difference did not affect core temperature, which decreased in a similar manner in both alcohol and control sessions (from 36.9 ± 0.1°C to 36.6 ± 0.1°C). Whole body sensations of cold and thermal discomfort became successively stronger in the control session, whereas these sensations were both greatly diminished after drinking alcohol. In a previous study we performed in the heat, using a similar protocol, alcohol produced a definite, coordinated effect on all autonomic and sentient heat loss effectors. In the current study in the cold, as compared to responses in the heat, alcohol intake was followed by lesser alterations in autonomic effector responses, but increased changes in sensations of temperature and thermal discomfort. Overall, our results indicate that although alcohol influences thermoregulation in the cold as well as in the heat, detailed aspects of the influence are quite different.     

Fos expression induced by warming the preoptic area in rats

The preoptic area (POA) occupies a crucial position among the structures participating in thermoregulation, but we know little about its efferent projections for controlling various effector responses. In this study, we used an immunohistochemical analysis of Fos expression during local warming of the preoptic area. To avoid the effects of anesthesia or stress, which are known to elicit Fos induction in various brain regions, we used a novel thermode specifically designed for chronic warming of discrete brain structures in freely moving rats. At an ambient temperature of 22 degrees C, local POA warming increased Fos immunoreactivity in the supraoptic nucleus (SON) and the periaqueductal gray matter (PAG). Exposure of animals to an ambient temperature of 5 degrees C induced Fos immunoreactivity in the magnocellular paraventricular nucleus (mPVN) and the dorsomedial region of the hypothalamus (DMH). Concurrent warming of the POA suppressed Fos expression in these areas. These findings suggest that thermal information from the preoptic area sends excitatory signals to the SON and the PAG, and inhibitory signals to the mPVN and the DMH.     

Urapidil zur Therapie von postanästhetischem Shivering nach Allgemeinanästhesie Eine placebokontrollierte Pilotstudie

Objective. Postanaesthetic shivering is common during recovery from general anaesthesia. Therefore we studied whether urapidil suppresses postanaesthetic shivering. Methods. With written informed consent and approval of the local ethics committee, patients (ASA I–II) recovering from general anaesthesia were monitored for 1 h. Patients with continuous shivering for a period of 5 min were randomly treated either with 5 ml placebo (isotonic saline) or 25 mg urapidil in a double-blind trial. This treatment procedure was repeated if shivering did not stop. A complete suppression of shivering was appraised as a sufficient treatment. Results. Shivering occurred in 20 of the patients studied and urapidil stopped shivering in 7 out of the 10 treated patients, whereas the placebo stopped shivering in only 2 out of 10 patients (P<0.05). Conclusion. In a placebo controlled trial, it was demonstrated that postanaesthetic shivering can be successfully treated by urapidil in 70% of the patients.     

Drug induced hypothermia in adult and senescent rats

Temperature regulation was evaluated in senescent (34-40 month old) and adult (8-9 month old) female Iva:WIWU and Emd:Wi-AF/Han rats. Injection of 1.5 mg/kg BW apomorphine HCl or 1.0 mg/kg BW oxotremorine sesquifumarate produced comparable maximal hypothermic responses in adult and senescent rats. However, the latency to reach maximal hypothermia after oxotremorine (but not apomorphine) was longer in senescent than in adult rats of both strains.     

Inheritance of amphetamine-induced thermoregulatory responses in inbred mice

Two inbred strains of mice, DBA/2 and C57BL/6, differ in their responses to d-amphetamine-induced alteration of core temperature. At low doses of amphetamine (e.g., 2 mg/kg IP), both strains become markedly hypothermic within 10-20 minutes. High doses (e.g., 20 mg/kg IP) induce significant hyperthermia (+1.8 degrees C) in DBA/2 mice but have only a slight hyperthermic effect (+0.2-0.3 degrees C) effect on C57BL/6 mice. The phenotype of the F1 hybrid strain derived by crossing C57BL/6 by DBA/2 is indistinguishable from its C57BL/6 parent at a dose of 20 mg/kg IP, i.e., reduced responsiveness to amphetamine-induced hyperthermia is dominant. Analysis of the thermoregulatory responses of recombinant inbred derivatives (lines BXD-9, 11, 15, 19, 20, 21, 23, 27, 28, 30) suggest that the relative responses to amphetamine-induced hyperthermia is inherited in a simple Mendelian fashion. These results differ from other pairs of inbred mouse strains which have been compared. These findings identify yet another neuropharmacological difference between mouse strains C57BL/6 and DBA/2 and are reviewed in terms of neuroregulatory mechanisms effecting thermoregulation.     

Potentiation of morphine hyperthermia in cats by pimozide and fluoxetine hydrochloride

Administration of morphine sulfate (1--4 mg/kg i.v.) to cats produces changes in body temperature, with hyperthermia appearing with larger doses. Since the central neurotransmitters dopamine and serotonin have been implicated in thermoregulation, studies were done to determine whether morphine's action could be mediated via these transmitters. Temperature responses were measured in freely moving cats by means of rectal thermometer probes. Either pimozide, 0.5 mg/kg i.p., a specific DA receptor blocker, or fluoxetine HCl, 10 mg/kg i.p., a specific inhibitor of 5-HT uptake, was administered 2--3 h prior to morphine injection. Temperatures were monitored for 3.5 h after morphine administration. Both agents were found to enhance the hyperthermic response to morphine with the maximum morphine effect occurring in most cases by 2 h. The results indicate that a balance in the ratio of 5-HT : DA may be involved in cat thermoregulation and that the hyperthermic response in the cat to morphine may be effected by shifting this 5-HT : DA ratio.