Kazuhiko Hirata

Retropharyngeal hematoma after stellate ganglion block: Analysis of 27 patients reported in the literature.

Background:Retropharyngeal hematoma (RPH) is rare; however, it causes airway obstruction and can be fatal. Stellate ganglion block (SGB) can cause RPH. The authors analyzed reports of patients with RPH after SGB to clarify the initial symptoms and signs, and the urgency of airway management. Methods:MEDLINE and Japana Centra Revuo Medicina were searched for reports of RPH after SGB using the following terms and key words: stellate ganglion block, complication, hematoma, and retropharyngeal hematoma. Results:The authors found 27 patients with RPH after SGB in the past 40 yr. The initial symptoms included neck pain (n = 10), dyspnea (n = 10), neck swelling (n = 8), and hoarseness (n = 5). The symptoms occurred 2 h or more after SGB in 14 patients (52%). Emergency airway management was needed in 21 patients (78%) because of airway obstruction. Among the 21 patients, orotracheal intubation was attempted first in 17 patients; however, it was unsuccessful in 5 patients who immediately needed emergency tracheostomy. Tracheal intubation was impossible by distortion of the anatomy of the markedly edematous pharyngolarynx. Failed airway management caused one death. There were no statistically significant predictors of the initial symptoms or signs for later emergency airway management. Conclusions:RPH after SGB necessitates emergency airway management. Because airway obstruction cannot be predicted by the initial symptoms or signs, emergency airway management tools should be at hand, and the patency of the airway should be continuously evaluated after onset of RPH after SGB.

Computer-assisted infrared thermographic study of axon reflex induced by intradermal melittin

Abstract The aim of the present study was to investigate whether melittin, the principal toxin of the honeybee (Apis mellifera) venom, can be used as an algogenic agent in the study of pain in humans. Five micrograms of melittin in 0.5 ml of saline was intradermally injected into the volar aspect of the forearm. Resultant pain was scored by a visual analogue scale (VAS), and skin temperature change was analyzed by means of a computer‐assisted infrared thermography. Intradermal melittin temporarily produced severe pain, followed by a sustained increase in skin temperature. The skin temperature increase peaked in about 10 min and outlasted 1 h. Topical application of 10% lidocaine gel did not significantly suppress the melittin‐induced pain, but markedly suppressed both the increase in the peak temperature and the area of temperature increase. In conclusion, 5 &mgr;g of melittin is sufficient to produce pain in humans and 10% lidocaine gel differentially decreases the melittin‐induced axon reflex without any significant analgesic effect.

Severity of skin lesions of herpes zoster at the worst phase rather than age and involved region most influences the duration of acute herpetic pain

Abstract Duration of acute herpetic pain (AHP) in 1431 patients for whom treatment was begun within 14 days after the onset of herpes zoster (HZ) was analyzed with respect to age, involved region, and severity of skin lesions. All patients were treated with repeated sympathetic nerve blocks until their pain was almost nil. Severity of the skin lesions at the worst phase was defined as mild when they covered less than one‐quarter of the primary dermatome, as severe when they covered more than three‐quarters of the primary dermatome, and moderate if they were between mild and severe. Without taking into account the severity of skin lesions, the duration of AHP for those aged 60 years or over and for those with trigeminal involvement was significantly longer than for patients aged under 40 years (P<0.01 and P<0.001) and for patients with thoracic (P<0.001) and lumbosacral (P<0.01) involvement, respectively. However, duration of AHP was significantly longer with increase in the severity of skin lesions in all age groups (the mild group versus the moderate group, P<0.01 and P<0.001; the moderate group versus the severe group, P<0.01 and P<0.001). The mean duration of AHP for patients aged 60 years or over with mild skin lesions ranged from 17.4 to 22.9 days, while that for patients aged 30–59 years with severe skin lesions ranged from 37.2 to 50.1 days. In addition, duration of AHP was significantly longer with increase in the severity of skin lesions in all regions (the mild group versus the moderate group, P<0.01 and P<0.001; the moderate group versus the severe group, P<0.05 and P<0.001). The mean duration of AHP for those with trigeminal involvement with mild skin lesions was 19.5 days, while the range was from 51.3 to 55.0 days for patients with severe skin lesions involving regions other than the trigeminal area. The frequency of severe skin lesions was significantly higher (P<0.001) in patients aged 60 years or over and in those with trigeminal involvement. Multiple stepwise regression analysis revealed that the most important factors influencing the duration of AHP were the severity of skin lesions of HZ at the worst phase (r=0.412), age (r=0.277) and the involved region (r=‐0.101). Thus, AHP in the elderly and in cases of trigeminal involvement is longer because of higher frequencies of severe HZ in the elderly and in trigeminal involvement rather than ‘being aged’ and ‘trigeminal involvement’ itself. We propose that one needs to analyze the results of treatment of AHP with respect to the severity of skin lesions at the worst phase.

Optimum pain relief with continuous epidural infusion of local anesthetics shortens the duration of zoster-associated pain.

Objective:To investigate effects of continuous epidural infusion (CEI) of 0.5% bupivacaine added to intermittent epidural boluses (IEB) on the duration of zoster-associated pain (ZAP), as compared with continuous infusion of normal saline placebo added to IEB. Design:A prospective, double-blind, randomized, placebo-controlled study. Setting:A university hospital and an affiliated clinic in Japan from 1996 through 1999. Patients:56 immunocompetent herpes zoster (HZ) patients, 50 years or older, within 10 days of rash onset and with severe pain and eruption. Interventions:Patients were hospitalized and randomly allocated into 2 groups. CEI group given CEI of 0.5% bupivacaine (0.5–1.0 mL/h) plus IEB of 0.5% bupivacaine 4 times daily (n = 29). IEB group given normal saline infusion plus IEB of 0.5% bupivacaine 4 times daily (n = 27). All patients received oral acyclovir 800 mg, 5 times daily, for 7 days. Outcome Measures:The number of days required for complete cessation of ZAP and the proportion of subjects with allodynia beyond 30 days. Results:The median time to cessation of ZAP was significantly shorter in the CEI group than in the IEB group (29 days vs. 40 days, P = 0.002). The number of patients whose allodynia persisted beyond 30 days of treatment was significantly lower in the CEI group than in the IEB group (10% vs. 37%, P = 0.027). Conclusions:CEI of 0.5% bupivacaine plus IEB was associated with a shorter duration of ZAP and fewer patients with allodynia beyond 30 days, compared with IEB plus normal saline infusion. Patients at high risk for developing postherpetic neuralgia (PHN) can be managed with intensive therapies at the early stage of disease, such as CEI, which maintains effective analgesia and may reduce the burden of PHN.

Biphasic vasomotor reflex responses of the hand skin following intradermal injection of melittin into the forearm skin

Melittin is the main toxin of honeybee venom. Previously, we have reported that intradermal injection of melittin into the volar aspect of forearm in humans produces a temporary pain and a subsequent sustained increase in the skin temperature due to axon reflex. To clarify the interaction between nociceptive inputs and vascular changes, we studied the influence of noxious stimulation by intradermal melittin on the vasomotor control of the distal extremities in human volunteers. Temperature changes of the bilateral palmar surface were recorded by means of a computer‐assisted infrared thermography. Unexpectedly, we found a biphasic response of skin temperature. The skin temperature of both fingers and hands decreased immediately after the melittin injection and then increased well above the control level, prior to the injection. There was a considerable individual variation in the baseline skin temperature, prior to melittin. The skin temperature in a finger/hand with lower preinjection value increased more markedly in the second phase. Consequently, the individual variation in the peak temperature of the second phase was less pronounced. The initial decrease was interpreted as sympathetic vasoconstrictor reflex induced by noxious stimulation and the later increase as release of sympathetic vasomotor tone.

High thoracic epidural block relieves acute herpetic pain involving the trigeminal and cervical regions: comparison with effects of stellate ganglion block.

Background and Objectives. Stellate ganglion block can promptly relieve acute herpetic pain (AHP) involving the trigeminal and cervical regions. However, repeated blocks are needed to maintain pain relief in most patients with severe AHP. Because continuous epidural block is easily performed using an indwelling catheter, we compared the effect of high thoracic epidural block with that of stellate ganglion block to relieve moderate‐to‐severe AHP involving these regions. Methods. Six patients received stellate ganglion blocks and seven patients received high thoracic epidural blocks. Six milliliters 1% of mepivacaine was given to each patient. Acute herpetic pain was evaluated before and up to 60 minutes after the blocks, using a visual analog scale (VAS) of pain. Results. There was no significant difference in VAS pain scores before the blocks between the groups, but there were significant (P < .05) decreases in VAS pain scores for both groups between 10 and 60 minutes after the blocks. There were no significant differences in VAS pain scores between the groups after the blocks. Conclusions. High thoracic epidural block was as effective as stellate ganglion block in relieving moderate‐to‐severe AHP involving the trigeminal and cervical regions.

The effects of clonidine and tizanidine on responses of nociceptive neurons in nucleus ventralis posterolateralis of the cat thalamus.

The effects of intravenous clonidine and tizanidine on nociceptive neurons in the nucleus ventralis posterolateralis (VPL) of the thalamus, a key station in the lateral system of ascending pain pathways, were evaluated in urethane-chloralose anesthetized cats. Intravenous clonidine and tizanidine produced a dose-dependent (5 and 10 micro gram/kg, and 25 and 50 micro gram/kg, respectively) suppression of responses of nociceptive specific (NS) and wide dynamic range (WDR) neurons in the VPL to high threshold splanchnic input. In contrast, the responses of both NS and WDR units to electrical stimulation of spinothalamic tract fibers in the ventrolateral funiculus (VLF) were little affected. We conclude that a site of suppressive action of the alpha2-adrenoceptor agonists, as observed in nociceptive VPL neurons, is at the level of the spinal dorsal horn rather than in the VPL itself. (Anesth Analg 1995;81:259-64)

Mexiletine-induced severe skin eruption, fever, eosinophilia, atypical lymphocytosis, and liver dysfunction

A 64-year-old man developed a severe generalized pruritic morbilliform skin eruption, fever, eosinophilia, atypical lymphocytosis, and liver dysfunction 30 days after ingestion of mexiletine, a sodium channel blocker, prescribed to treat postherpetic neuralgia. Following intravenous dexamethasone, body temperature normalized the next day. However, the skin eruption did not disappear completely for 4 weeks. The patch test was positive for mexiletine. Clinical features and the result of patch test indicated that the patient developed hypersensitivity syndrome, a severe adverse cutaneous drug reaction, caused by mexiletine. We propose that mexiletine be added to the list of drugs that can cause severe adverse cutaneous drug reactions and that patients receiving mexiletine be warned to stop taking the drug immediately if a skin eruption occurs.

Splanchnic neurolysis using carbon dioxide as the contrast agent.

Background and Objective Iodinated contrast agents are usually used to verify correct spread of injectate during splanchnic neurolysis. We performed a splanchnic neurolysis by using carbon dioxide as the contrast agent in a patient who was allergic to iodinated contrast agents. Case Report A 49-year-old man had severe upper abdominal and back pain due to chronic pancreatitis. Because slow-release morphine 360 mg a day and epidural fentanyl 500 μg a day did not relieve the pain, a splanchnic neurolysis was performed by the posterior approach. The needle tip was placed into the retrocrural space under fluoroscopic guidance. Fifteen milliliters of carbon dioxide was injected as the contrast agent. It gave a less clear image than that obtained by iodinated contrast agents; however, the correct spread of the gas was easily visible under continuous fluoroscopy. Six percent aqueous phenol 8 mL was injected after confirming relief of the pain with a local anesthetic. The dose of slow-release morphine was gradually decreased after the procedure. His abdominal and back pain was controlled with slow-release morphine 120 mg a day. Conclusion Carbon dioxide was useful as the contrast agent to perform splanchnic neurolysis. Reg Anesth Pain Med 2003;28:68-69.

Risk Vessels of Retropharyngeal Hematoma During Stellate Ganglion Block

Background and Objective Bleeding into the retropharyngeal space is a potential complication in stellate ganglion block (SGB). Retropharyngeal hematoma formation is considered to be due to damage of small arteries in the region, although only scanty details of the region are available. The aim of this study was to map the risk blood vessels in the retropharyngeal space to avoid accidental damage during SGB. Methods Contrast-enhanced 3-dimensional computed tomography images performed on 80 patients were reanalyzed retrospectively to construct detailed map of cervical blood vessels that are prone to damage and bleeding during SGB. Results Of the 160 bilateral necks, 6 (3.8%) and 82 (51.3%) small arteries were identified in the medial portions of the ventral surface of the transverse processes of the sixth and seventh cervical vertebrae, respectively. In particular, 5 of the 6 small arteries detected in the medial portion of the ventral surface of the transverse process of the sixth cervical vertebra were the inferior thyroid artery (ITA). Of the 160 vertebral arteries, 2 arteries were missing, 4 (2.5%) entered the transverse foramen of the fifth cervical vertebra, whereas 1 artery (0.6%) entered the transverse foramen of the fourth cervical vertebra. Conclusions Three-dimensional computed tomography identified the ITA in the medial portion of the ventral surface of the transverse process of the sixth cervical vertebra. The risk vessels of retropharyngeal hematoma during SGB could include the ITA.