Sympathetic skin response: a new test to diagnose ejaculatory dysfunction

Sympathetic skin responses were elicited from the palm and sole (plantar) with electrical stimulation on the dorsal nerve of the penis in 24 individuals. The palmar and plantar sympathetic skin responses were obtained in 12 subjects with normal ejaculatory function. On the other hand, the plantar sympathetic skin response was absent in 11 of 12 patients who lacked ejaculation. Since the plantar sympathetic skin response is correlated closely to the mechanism of ejaculation, this test is expected to be helpful to diagnose sexual dysfunction and to monitor the effects of treatment.     

Changes in Skin Blood Flow and Temperature during Spinal Analgesia Evaluated by Laser Doppler Flowmetry and Infrared Thermography

Changes in skin blood flow and skin temperature during spinal analgesia and "sham" spinal analgesia were studied using laser Doppler flowmetry and skin temperature measurements on patients scheduled for transurethral resection. Infrared thermography was also used. During "sham" spinal analgesia skin blood flow decreased 17.7% +/- 37% (s.d.) and skin temperature fell 0.05 degrees C +/- 0.6 (s.d.) degree C. The height of the blockade was T10 or above in all cases. Using the laser Doppler technique with measuring points from the clavicle to T12, a tendency towards increased skin blood flow was seen in six cases out of 20 at T10 (significant elevations in 3/20) and in 14 cases out of 20 at T12 (significant elevations in 7/20). Skin temperature measurements and thermography showed a tendency towards cooling in the thoraco-abdominal region in the vast majority of the cases and a marked temperature elevation in the foot only. No differences between hyperbaric and glucose-free solutions for spinal analgesia were noticed. The conclusion of this study is that during spinal analgesia the extent of sympathetic blockade is less than the extent of analgesia.     

Effects of epidural anesthesia on sympathetic nerve discharge to the skin

Direct intraneural recordings of skin sympathetic activity (SSA) were performed to determine the magnitude of blockade of sympathetic fibers to the lower extremities during epidural anesthesia. Lumbar epidural catheters were inserted in nine volunteers. Multiunit postganglionic sympathetic activity was recorded in a skin fascicle of the peroneal nerve before and after injection of 4 ml of mepivacaine 2% epidurally, followed by an additional 12-16 ml after 5 min. Arousal stimuli such as sudden loud noises and noxious electrical skin stimulation were used to elicit transient sympathetic activation. Epidural anesthesia with upper level of sensory blockade at T4-T8 (n = 7) completely blocked spontaneous SSA and no detectable skin sympathetic activity could be provoked by arousal stimuli later than 14 min after the test dose. Sympathetic blockade was accompanied by marked increases in foot skin blood flow and loss of skin resistance responses to arousal. Epidural anesthesia with sensory blockade up to T10-11 (n = 2) only produced a partial sympathetic blockade. The result shows that epidural anesthesia with sensory blockade at T8 or above is equally as effective as injections of local anesthetics directly at postganglionic nerve fibers or ganglionic blockade in producing a complete sympathetic blockade of intraneurally recorded SSA. This neural blockade was paralleled by skin vasodilatation and a loss of sudomotor responses in the foot.     

Bladder neck incompetence in patients with spinal cord injury: significance of sympathetic skin response

PURPOSE: We investigated whether recording the perineal sympathetic skin response, which reflects the sympathetic function of the thoracolumbar spinal cord, represents a reliable and accurate diagnostic tool for assessing bladder neck competence and incompetence. MATERIALS AND METHODS: We compared the sympathetic skin response recorded from the hand, foot and perineal skin with urodynamic findings in 90 patients with neurogenic bladder dysfunction, including 66 with spinal cord injury and 24 with cauda equina lesions. RESULTS: Video urodynamics revealed an incompetent bladder neck in 11 of 32 patients (34%) with complete and 7 of 34 (21%) with incomplete spinal cord injury but in only 1 of 24 (4%) with the conus-cauda equina syndrome. This association significantly correlated with the lesion level at T10 to L2 in 12 of 26 cases (46%) as well as with the loss of perineal but preserved hand and foot sympathetic skin response in 13 of 18 (72%). CONCLUSIONS: Recording the perineal sympathetic skin response in addition to that of the hand and foot represents a sensitive diagnostic tool for assessing sympathetic nerve function within the thoracolumbar spinal cord. It is of diagnostic value for evaluating neurogenic bladder neck incompetence in spinal cord injured patients.     

The relation between skin temperature increase and sensory block height in spinal anaesthesia using infrared thermography

Background and objectives: To evaluate the feasibility of determining the extent of sympathetic blockade by skin temperature measurement with infrared thermography and relate the cranial extent of the temperature increase to that of the sensory block after spinal anaesthesia. Methods: Before and 5, 10 and 20 min after the administration of spinal anaesthesia, skin temperatures were measured with infrared thermography at the dermatomes T2–L3, in 12 male patients scheduled for lower limb surgery. The most cephalad dermatome at which sensory blockade occurred was related to the dermatome at which the largest temperature jump (corrected for baseline temperature) occurred. Results: The baseline temperatures showed considerable variation across the dermatomes, being lower below T12 than at the thoracic dermatomes. The mean difference between the level of the cephalad skin temperature elevation front (mean 1.03 °C, SD 0.8 °C) and cranial sensory block height was 0.10 dermatomes (SD 1.16), correlation coefficient (0.88, P<0.001). Conclusion: The varying baseline temperatures across the trunk, the limited sympathetic block‐induced increase in skin temperature at the trunk and the difficult control of influences from the surroundings partly obscured the extent of the skin temperature increase and its correlation to sensory block height. These factors have to be controlled to improve the use of infrared cameras as an easy bedside tool for predicting the cranial extent of (sympathetic blockade during) spinal anaesthesia.     

The Value of Sympathetic Skin Response Recordings in the Assessment of the Vesicourethral Autonomic Nervous Dysfunction in Spinal Cord Injured Patients

Purpose

We assessed the degree of sparing of the descending sympathetic spinal tract and correlated these findings with bladder neck function in spinal cord injured patients.

Materials and Methods

Sympathetic skin responses of the right hand and foot were recorded and compared to the urodynamic findings in 27 spinal cord injured patients.

Results

All tetraplegic and paraplegic patients with a lesion above the T6 level who presented with bladder neck dyssynergia associated with autonomic hyperreflexia had abnormal sympathetic skin responses in the right hand and foot. All patients with a lesion below the T6 and above the T12 levels with an abnormal sympathetic skin response in the right foot also had bladder neck dyssynergia.

Conclusions

Evidence is presented that the integrity of the descending sympathetic spinal tract is necessary for a synergic function of the vesicourethral complex and that sympathetic skin responses are of value in the diagnosis of bladder neck dyssynergia. For lesions below the T12 level other investigative methods to exclude bladder neck dyssynergia are necessary.     

A new approach in the management of chronic nonhealing leg ulcers.

Chronic leg ulcers are a major cause of mortality and morbidity. The efficacy of hyperbaric oxygen treatment is being evaluated in the management of nonhealing leg ulcers to improve skin graft survival. Twenty-seven patients with 36 chronic leg ulcers were examined. Each wound received 12 preoperative hyperbaric oxygen treatments, split-thickness skin grafting, followed by 12 postoperative hyperbaric oxygen treatments. Wound transcutaneous oxygen tension measurements (TCOM) were taken. The graft take was evaluated. At 18 months follow-up, 18 skin grafts (50%) showed complete take, 15 (41.7%) demonstrated partial take, and 3 (8.3%) failed. Hyperbaric oxygen treatment is an effective adjunct in the management of chronic leg ulcers, and its use resulted in increased graft take and survival.     

Uniform distribution of skin-temperature increase after different regional-anesthesia techniques of the lower extremity

BACKGROUND AND OBJECTIVES: Skin-temperature increase is a reliable but late indicator of success during regional-anesthesia techniques. The goal of this study is to determine the distribution of skin-temperature changes during different regional techniques. Does skin temperature increase in the whole area innervated by the blocked neural structures or only in certain regions within this area with the capability to react preferentially to sympathetic block (i.e., vessel-rich skin)? Although onset time may vary between different regional-anesthetic techniques, we hypothesized that the distribution of skin warming is equal. METHODS: Skin temperature was assessed continuously by infrared thermography in 24 patients who received either combined femoral-nerve and sciatic-nerve block, epidural anesthesia, or spinal anesthesia. RESULTS: Apart from differences in time of onset, no differential spatial distribution of skin-temperature changes could be detected. The earliest and greatest rise of skin temperature occurred at the great toe (10.6 degrees C +/- 0.4 degrees C), became smaller proximally, and was negligible above the ankles, irrespective of the type and extent of block. Video-thermography revealed that cold blood flows through subcutaneous veins immediately after onset of sympathetic block and initially decreases skin temperature (0.6 degrees C +/- 0.3 degrees C) during onset of spinal anesthesia. CONCLUSION: Irrespective of the applied regional-anesthetic technique, skin-temperature changes are more pronounced distally. Thermography prevents false measurements of skin temperature above subcutaneous veins and displays flow of cold blood as the mechanism of initial skin-temperature drop after regional anesthesia. Measurements of skin-temperature increase cannot be used to evaluate the extent of analgesia or sympathetic block.     

Intraneural recording of muscle sympathetic activity during epidural anesthesia in humans

The extent and magnitude of sympathetic blockade during epidural anesthesia have previously been assessed only by indirect methods. In this study, direct intraneural recordings of muscle sympathetic activity (MSA) in the peroneal nerve was performed to determine the profundity of blockade of sympathetic fibers to the lower extremities during epidural anesthesia. Lumbar epidural catheters were inserted in nine volunteers. Multiunit postganglionic sympathetic activity was recorded in a muscle fascicle of the peroneal nerve before and after epidural injection of 4 mL of 2% mepivacaine followed by an additional 12-16 mL after 5 min. Apnea (30-60 s) was used to elicit transient sympathetic activation. The upper level of sensory blockade was T-3 to T-10. Muscle sympathetic activity decreased after epidural blockade with no spontaneous or apnea-induced sympathetic bursts observed later than 11 min after injection of the initial test dose. Sympathetic blockade was accompanied by increase in foot skin blood flow as well as loss of skin resistance responses to arousal. Results show that epidural anesthesia with sensory blockade above T-10 to T-11 blocks spontaneous peroneal MSA as well as the marked sympathetic activation induced by apnea.     

Skin conductance as a means to predict hypotension following spinal anaesthesia

Background and objective: Hypotension following spinal anaesthesia (SA) is common, especially in the elderly. Elevated sympathetic tone has been shown to correlate with severe hypotension after SA. The aim of this prospective trial was to investigate skin conductance (SC), as a measure of sympathetic tone, to predict hypotension after SA. Methods: After ethical approval and written informed consent, 30 patients undergoing SA were included. Baseline measurements of SC [number of fluctuations per second (reflecting the firing rate of skin sympathetic nerves), area under the curve (AUC) A and B (reflecting the magnitude of the sympathetic impulse)], blood pressure and heart rate were recorded. After administration of SA, all parameters were assessed every 2.5 min for a total of 15 min. Baseline readings of SC were compared with the lowest blood pressure within the study period. Results: Data from 30 subjects [73 (8) years] were analysed. After SA, the mean arterial blood pressure declined an average of 21.3 (11.3) mmHg. A cut‐off value of 0.35 μSs for baseline AUC B allowed prediction of more than mild hypotension (>15% from baseline) after SA with a sensitivity of 72.5% and a specificity of 77.5%. Conclusions: AUC B, as a parameter of SC, may predict severe arterial hypotension after SA in the elderly.     

Assessment of sympathectomy--the skin potential response

Objective assessment of the results of surgical sympathectomy and sympathetic block (both temporary and permanent) are not widely practised. This article comments briefly on the available methods, and describes the use of the abolition of the skin potential response (formerly known as the psychogalvanic reflex) to assess the abolition of sympathetic function. This method of assessment has proved useful in clinical practice.     

Blood flow, sympathetic activity and pain relief following lumbar sympathetic blockade or surgical sympathectomy

The physiological effects of local anaesthetic (bupivacaine), neurolytic (phenol) blockade and surgical ablation of the lumbar sympathetic chain were assessed in patients with peripheral vascular disease or sympathetic dystrophy. Local anaesthetic blockade in 49 patients resulted in significant decrease in pain, plantar sweating and in the vasoconstrictor ice response of the foot, as well as a significant increase in skin temperature and foot blood flow. Subsequent neurolytic blockade in 31 of these patients achieved an effective denervation as assessed by the same physiological measurements. The magnitude of changes in blood flow and sympathetic activity were similar for local anaesthetic and neurolytic blockade as well as in six patients who underwent surgical sympathectomy.     

Usefulness of galvanic skin reflex monitor in CT-guided thoracic sympathetic blockade for palmar hyperhidrosis

Computed tomography (CT)-guided thoracic sympathetic blockade with ethanol was performed while monitoring sympathetic nerve activity, with an alternating current (AC) galvanic skin reflex (GSR) monitor, in a patient with palmar hyperhidrosis in whom endoscopic thoracic sympathectomy was impossible because of pleural adhesion. Sweating was suppressed after the thoracic sympathetic blockade, and the monitor showed a significant increase in skin resistance. The effect of sympathetic blockade could be evaluated directly and in real time using a GSR monitor.     

Sympathetic blockade increases tactile sensitivity

To determine whether tactile sensitivity of the normal skin is altered by suppression of sympathetic efferent activity, the effect of stellate ganglion block and epidural sympathetic block on touch threshold was studied. The study was performed on ten individuals with various chronic pain syndromes. Tactile sensitivity was measured in the normal skin area with the use of von Frey filaments and a two-alternative forced-choice procedure with a staircase presentation of touch stimuli. With stellate ganglion block, touch threshold decreased on the side of the block by 48.8 +/- 8.% (P = 0.002) without any significant change in the threshold on the healthy, nonblocked side (P = 0.003 for the difference between the sides). With epidural sympathetic block, touch threshold decreased to the same extent on the diseased and healthy sides, which were both affected by the block (46.2 +/- 11.4%, P = 0.027 and 47.7 +/- 12.5%, P = 0.032, respectively). The results show that sympathetic blockade increases tactile sensitivity. They also suggest that sympathetic efferent activity modulates the function of tactile receptors. It is hypothesized that the sympathetic modulation makes tactile receptors less sensitive to touch, less specific, and probably more prone to code tactile stimuli in such a way that the brain recognizes this code as pain.     

A single-injection, multi-segmental paravertebral block-extension of somatosensory and sympathetic block in volunteers

BACKGROUND: It is our experience that a deposition of an anesthetic solution in the ventral area of the paravertebral space near the parietal pleura and the sympathetic trunk produces extended unilateral block. Because sympathetic block effects in this extended paravertebral block are not reported yet, we undertook this singly blinded, controlled study on the sympathetic change in volunteers. METHODS: A total of 22 ml 1% lidocaine was injected at the T11 level into the ventral area of the right-sided paravertebral space in 16 volunteers. The distribution of analgesia, heart rate, blood pressure and body temperature (measured by 12 skin sensors) was monitored. On a later occasion the volunteers underwent a control injection of saline. RESULTS: Unilateral analgesia (with no contralateral element) was induced in every subject injected with lidocaine, contrasted with no block induction with saline. Loss of pin-prick sensation was observed within 10 min after injection and involved a mean of 12 (range 8-13) dermatomes. A sympathetic block was indicated by cutaneous temperature increase within at least 6 dermatomes. Increase of arterial blood pressure was obtained in all volunteers with no change in pulse rate. No side effects or complications occurred. Epidural spread of the local anesthetic was unlikely because of the absence of contralateral cutaneous analgesia and temperature increase. CONCLUSION: One-sided extended analgesia (sensory loss) follows the paravertebral injection of lidocaine. A large ipsilateral sympathetic block is observed without change in pulse rate and with no hypotension. These are all characteristics of an optimal regional block.     

Anatomy of the spinal nerves and dermatomes

There are 31 pairs of spinal nerves: eight cervical, 12 thoracic, five lumbar, five sacral and one coccygeal. They form by fusion of a posterior sensory spinal root (bearing its posterior root ganglion) with an anterior motor root. These join at each intervertebral foramen. Typically, the nerve then divides into a posterior and an anterior primary ramus. The former supplies the vertebral muscles and dorsal skin. The anterior primary ramus in the thoracic region bears a white ramus communicans to the sympathetic ganglion. Each spinal nerve receives a grey ramus from the sympathetic chain. The nerves T2–T12 supply the skin and muscles of the trunk sequentially. The other nerves are arranged into the cervical, brachial, lumbar and sacral plexuses. The cervical plexus supplies the skin and anterior muscles of the neck and forms the phrenic nerve (C3–C5), while the brachial plexus supplies the skin and muscles of the upper limb, and the lumbar and sacral plexuses supply the skin of the lower limb and perineum and the muscles of the posterior abdominal wall, pelvis, perineum and lower limb. The segmental nerves are arranged to supply the skin (dermatomes), while the segmental supply to the limb muscles, the myotomes, is more complex.     

EFFECTS OF SEGMENTAL THORACIC EXTRADURAL ANALGESIA ON SYMPATHETIC BLOCK IN CONSCIOUS DOGS

To test the hypothesis that segmental thoracic extradural blockcauses sympathetic denervation caudally beyond dermatomes renderedanalgesic, we have measured regional skin temperatures in sixconscious dogs after upper thoracic, mid thoracic, and lumbarextradural injection of 0.5% bupivacaine 0.5, 1 and 2 ml cumulatively(total dose: 3.5 ml) given at 45-min intervals. Dogs were studiedat constant ambient and rectal temperatures. Upper thoracicextradural injections resulted in a significant increase inskin temperatures on both the front (+ 1.4 (SEM 0.2) °C)and hind paw (+ 1.4 (0.3) °C), while the area of analgesiawas confined to the upper trunk. With lumbar extradural injection,skin temperatures increased significantly (+2.0 (0.5) °C)on the lower extremities only. Mid thoracic injection significantlyincreased both front (+2.4 (0.9) °C) and hind paw (+2.2(0.6) °C) skin temperatures, but decreased temperatureson the thorax (–0.9 (0.2) °C) and abdomen (–1.0(0.2) °C), reversing the normal temperature gradient alongthe body axis. Irrespective of the injection site, skin temperatureson the trunk failed to increase or even decreased significantly.These data suggest that small doses of local anaesthetics appliedto the extradural space of conscious dogs cause increased lowerextremity skin temperatures caudal to areas unresponsive topinprick stimulation when injected at a high thoracic level,and decreased trunk skin temperature even in analgesic areas,so that skin temperature measurements are unlikely to reflectpurely sympathetic efferent activity on the trunk. Upper thoracicsegmental extradural analgesia induced a decrease in sympathetictone distal to the area of analgesia.     

Can galvanic skin response be used as a quantitative estimate of sympathetic nerve activity in regional anesthesia?

To study the relationship between skin sympathetic nerve activity and changes in skin resistance (galvanic skin response--GSR), efferent sympathetic and sensory nerves to the hand were blocked by an axillary nerve blockade in 15 healthy subjects. Subsequently, intraneural electrical stimuli in the median nerve distal to the axillary nerve block were used to evoke changes in skin resistance and in water vapor partial pressure in the sensory and sympathetically denervated hand. With increasing frequency of stimulation, skin resistance decreased and water vapor partial pressure increased until stimuli exceeded 10 Hz. When an additional burst of impulses was added to the background stimulation, GSR amplitude varied in a nonlinear fashion with the background frequency. Stimulation-induced GSR was completely abolished in a dose-dependent manner by systemically (intravenously) administered atropine. The results indicate that GSR depends on the preceding level of nerve traffic in the sympathetic sudomotor nerve fibers. Consequently, skin resistance recordings cannot be used to quantify sympathetic nerve traffic and thus do not express the completeness of sympathetic blockade in regional anesthesia.     

Percutaneous lumbar sympathectomy: a comparison of radiofrequency denervation versus phenol neurolysis

A new percutaneous approach to sympathectomy using radiofrequency denervation has seemed to offer longer duration and less incidence of postsympathetic neuralgia as compared to phenol sympathetic blocks. To compare these techniques, 17 patients underwent either phenol lumbar sympathetic blocks (n = 9) or radiofrequency denervation (n = 8). Duration of sympathetic block was followed by a sweat test and temperature measurements. Results indicate that 89% of patients in the phenol group showed signs of sympathetic blockade after 8 weeks, as compared to 12% in the radiofrequency group (P less than 0.05). Although the incidence of post sympathetic neuralgia appears to be less with radiofrequency denervation, further refinement of needle placement to ensure complete lesioning of the sympathetic chain will be required before the technique can offer advantages over current phenol techniques.