Assessment of the neurogenic flare reaction in small-fiber neuropathies

To improve sensitivity of the analysis of axon reflex flare reaction, the authors used a laser Doppler scanner and analyzed flare intensity and size induced by histamine iontophoresis simultaneously at the foot and thigh in patients with small-fiber neuropathy (n = 10) and controls (n = 9). Flare size, but not laser Doppler flux, clearly distinguished patients from controls at both locations (p < 0.01) and may be useful for evaluation of small-fiber neuropathies.

Dermal microdialysis provides evidence for hypersensitivity to noradrenaline in patients with familial dysautonomia

OBJECTIVES

To use the technique of dermal microdialysis to examine sensitivity of skin vessels to noradrenaline (NA) in patients with familial dysautonomia (FD) and in healthy controls.

METHODS

In 14 patients with FD and 12 healthy controls, plasma extravasation, local laser Doppler blood flow, and skin blanching were observed before, during, and after application of 10(-6) M NA through a microdialysis membrane, located intradermally in the skin of the lower leg.

RESULTS

Maximum local vasoconstriction measured by laser Doppler blood flow did not differ between patients with FD and controls. In contrast, patients with FD had an earlier onset of vasoconstriction (p = 0.02). Moreover, reaction to NA was more prominent and prolonged in FD, shown by a larger zone of skin blanching around the microdialysis membrane (p < 0.001) and delayed reduction of the protein content in the dialysate after termination of NA application (p = 0.03).

CONCLUSION

These data support the hypothesis that peripheral blood vessels of patients with FD show a denervation hypersensitivity to catecholamines. This may be one mechanism contributing to the major hypertension that frequently occurs during "dysautonomic crises" in FD.

Power spectral analysis of heart rate variability during positive pressure pneumoperitoneum: the significance of increased cardiac sympathetic expression

BACKGROUND

Positive pressure pneumoperitoneum (PPP) effects on the autonomic nervous system (ANS) might be of clinical importance, as imbalance in the autonomic cardiac control might lead to serious consequences.

METHODS

Fifteen healthy patients undergoing elective laparoscopic cholecystectomy were analyzed for cardiac autonomic nervous activity by spectral heart rate variability, during awake state, before and after intubation, during CO2 PPP (14 mmHg), and after CO2 evacuation. The very low, low, high and very high frequency (VLF, LF, HF, VHF respectively) bands of the spectral density of the heart rate variability (HRV) and their normalized values, as well as the LF/HF ratio, were obtained from the power spectra of R-R intervals, using the fast-Fourier transformation algorithm.

RESULTS

Using Friedman's nonparametric test, only the difference between the power of LF during anesthesia (median 30.74) and the middle of PPP (median 195.66) was found to be significant (p<0.012). Such change was recorded in 14 patients (p = 0.001, sign test).

CONCLUSIONS

Increased LF power reflects sympathetic cardiac activation. As the LF range accounts for regulation of blood pressure and baroreflex, several mechanisms may explain this activation. This in turn may predispose patients who suffer from cardiac disease to higher risk of developing ventricular arrhythmias, besides the possible adverse hemodynamic consequences of PPP.

[Effects of recommendations and patient seminars on effectivity of outpatient treatment for headache]

BACKGROUND

Treatment of patients suffering from migraine and/or tension-type headache in primary care needs to be improved. To this purpose we tested two strategies for implementation of evidence-based recommendations for treatment of headaches: first, communication of recommendations to the primary care physicians and, second, standardized communication and discussion of these recommendations with patients in combination with exercising of progressive muscle relaxation during patient seminars.

METHODS

Patients with at least 2 migraine attacks/month or 8 days of tension-type headache/month were included in the study. Evidence-based pharmacological and non-pharmacological recommendations of the Medicines Committee of the German Medical Profession for treatment of migraine and tension-type headache have been offered to primary care physicians by printed material and during conferences. Patient seminars at 10 days for 2 hours were organized by the outpatient pain facility of the neurological department of the university of Erlangen. During seminars the patients were informed about these recommendations and learned progressive muscle relaxation. Agreed therapy between physician and patient was documented by physicians and patients during a 6 months treatment interval and compared with the recommended therapy. Effectivity of treatment was assessed by pre-post changes of days of headache/month, attack frequency/month, headache intensity (visual analogue scale), pain related impairment (German version of the Brief Pain Inventory), and health related quality of life (German Version of the SF-36). 51 patients were documented by 24 primary care physicians after communication of recommendations and 46 patients completed the patient seminar. Data of both groups were compared with those of 80 patients from primary care physicians before interventions.

RESULTS

Communication of recommendations for headache therapy to primary care physicians did not improve conformity of the agreed therapy with the recommended. Contrary conformity of the agreed therapy for pharmacological treatment of migraine attacks and interval therapy of migraine by progressive muscle relaxation with the recommended therapy improved significantly. However, interventions did not significantly improve the outcome quality of outpatient treatment as compared to the therapy of primary care physicians before interventions.

CONCLUSION

Effectivity of headache treatment in primary health care could not be improved by communication of evidence-based recommended therapy to primary care physicians nor by direct information of patients about these recommendations in combination with provided availability to learn progressive muscle relaxation.

The laparoscopic approach to abdominal hydatid cysts: a prospective nonselective study using the isolated hypobaric technique

HYPOTHESIS

The laparoscopic isolated hypobaric technique that we developed and use is safe and feasible for almost all kinds of hepatic and extrahepatic abdominal hydatid cysts.

DESIGN

A case series.

PATIENTS

Between August 1992 and December 1999, 31 patients with no selection criteria underwent 32 consecutive laparoscopic operations for 52 symptomatic hydatid cysts located in the liver (49), spleen (1), and pelvis (2). Eleven patients underwent surgery for between 2 to 5 cysts.

INTERVENTIONS

The main surgical maneuvers (puncture, parasite neutralization, and complete evacuation) were performed through an assembled transparent cannula, in which a vacuum was created, while its tip adhered firmly to the cyst wall. Following evacuation of the cyst contents, we attempted to perform partial pericystectomy, omentoplasty, and closed-suction drainage.

MAIN OUTCOME MEASURES

Surgical complications and postoperative disease recurrence.

RESULTS

Mean cyst diameter was 8.4 cm (range, 3.5-25 cm). Seven cysts were subdiaphragmatic, and 6 were on the posterior (hidden) aspect of the liver. Mean postoperative follow-up was 49 months. Forty-one cysts contained live parasites, and 11 were secondarily infected. Twenty-four cysts were complex. Perioperative complications occurred in 5 patients, including 1 patient who died 1 month after surgery owing to Candida sepsis. Mean hospital stay was 6 days. No evidence of recurrence was recorded during follow-up.

CONCLUSIONS

The isolated hypobaric laparoscopic technique described provides a safe and efficacious approach to almost all types of abdominal hydatid cysts and takes advantage of the recognized benefits of the laparoscopic approach.

Central and peripheral adverse hemodynamic changes during laparoscopic surgery and their reversal with a novel intermittent sequential pneumatic compression device

OBJECTIVE

To study the influence of a novel intermittent sequential pneumatic compression device (Lympha-press) on the adverse cardiac and peripheral hemodynamic changes induced by positive-pressure pneumoperitoneum (PPPn) in laparoscopic surgery.

SUMMARY BACKGROUND DATA

Creation of PPPn is known to cause adverse central and peripheral hemodynamic changes. An intrasubject observational study was undertaken to quantitate these adverse changes and to assess the influence of an intermittent sequential pneumatic compression system on these adverse hemodynamic changes during laparoscopic surgery with PPPn.

METHODS

The study involved 16 consecutive patients undergoing laparoscopic surgery with PPPn of 12 mmHg and 30 degrees head-up tilt position. The following peripheral hemodynamic recordings were made using Doppler ultrasound: peak systolic velocity (PSV), end diastolic velocity (EDV), and cross-sectional area of the femoral vein. Central monitoring included cardiac output and stroke volume by transesophageal Doppler, blood pressure, and pulse. The hemodynamic state based on these parameters was assessed before induction of PPPn with the anesthetized patient in the supine position, after induction of PPPn and head-up tilt position with Lympha-press off, and during PPPn and head-up tilt position with Lympha-press on, and after desufflation with the patient in the supine position under general anesthesia.

RESULTS

Positive-pressure pneumoperitoneum and the head-up tilt position resulted in a 33% reduction in PSV, a 21% reduction in EDV, and a 29% increase in cross-sectional area of the femoral vein. This was associated with a 20% reduction in cardiac output and an 18% reduction in stroke volume. Activation of Lympha-press during PPPn and the head-up tilt position resulted in a 129% increase in PSV and a 55% increase in EDV by 55%. It also increased the cardiac output by 27% and stroke volume by 16%, with no effect on cross-sectional area. Compared with the pre-PPPn stage, there was no difference in cardiac output or stroke volume, but the PSV was higher by 78% and the EDV by 32%. After abdominal desufflation in the supine position, the cardiac output and stroke volume were restored to the pre-PPPn level, but persistent and significant elevations were observed during the period of study in PSV, EDV, and cross-sectional area.

CONCLUSIONS

Significant and individually variable central and peripheral hemodynamic changes are encountered during laparoscopic surgery with PPPn and the head-up tilt position. These are reversed by intermittent sequential pneumatic compression using Lympha-press.

[Outcome-quality of treatment for headache on primary care conditions]

BACKGROUND

Little is known about the outcome-quality of treatment for headache on primary care conditions in Germany.

METHODS

All physicians (2100) of middle franconia, a bavarian greater district with 1,6 Mio. inhabitants, involved in outpatient management were asked to include consecutively patients in the study which suffer from migraine (at least 2 attacks/month) and/or tension type headache (at least 8 days/month) of at least 4 weeks duration. Before and after a 6 months interval patients documented the following outcome data in a questionnaire: pain intensity during the last attack (numeric rating scale), pain dependent disability (Brief Pain Inventory, German version), health related quality of life (SF-36, German version) and depressivity (Allgemeine Depressionsskala). The pain chronification state (Mainz Pain Staging System) has been assessed by the physician. Therapy was not standardized and included the natural spectrum of medicamental and non-medicamental therapy of headache. Agreement of therapy with recommendations of the "Arzneimittelkommission der Deutschen Aerzteschaft" has been assessed.

RESULTS

24 physicians participated in the study. Pre-post-data of 80 patients (46+/-14 y) could be analysed. Initially 67% were classified in pain chronification state I, 27% in state II and 6% in state III. Medicamental therapy agreed with recommendations in approximately 50% of patients, non-medicamental therapy has been used rarely. The pain intensity, pain dependent disability, depression and quality of life improved significantly. 45% and 55% of patients improved in at least 2 of 6 outcome-parameters by 30% of baseline value or by half standard deviation of the corresponding pre-post-differences, respectively. The latter outcome-measure reflects a medium effect size.

CONCLUSIONS

On primary care conditions about 50% of patients suffering from migraine and/or tension type headache (predominantly low chronification stae) perceive a therapy effect that corresponds to a medium effect size.

Density of sympathetic axons in sural nerve biopsies of neuropathy patients is related to painfulness

In this study, differences of unmyelinated nerve fiber density in sural nerve biopsy material from patients suffering from neuropathies of unknown origin with (n=14) or without pain (n=13) were analyzed. Immunocytochemistry was applied to differentiate afferent sensory and efferent sympathetic nerve fibers. All patients were evaluated for deficits of small fiber function with thermotesting, quantitative sudomotor-axon reflex-testing and testing of painfulness of mechanical stimuli before performing the biopsy. No difference was found between patients with and without pain concerning clinical deficits or results in any of the neurophysiological examinations. There were also no histopathological differences concerning the density of afferent C-fibers. However, absolute and relative density of efferent sympathetic nerve fibers was significantly higher in patients with painful neuropathy (P<0.001), although none of the patients demonstrated clinical sympathetic abnormalities. We conclude that an imbalance between afferent and sympathetic nerve fiber density in the periphery may contribute to neuropathic pain even in those patients without obvious clinical autonomic disturbances.

Xanthogranulomatous appendicitis--an incidental finding of localized pathology

The clinical, histopathological, and electron microscopic features of an unusual case of xanthogranulomatous appendicitis are reported. The patient, a 37-year-old female, presented with typical signs of acute appendicitis and the appendix appeared slightly dilated at laparatomy. The histopathological sections showed numerous xanthoma cells mixed with inspissated fecaliths. Electron microscopy disclosed the presence of xanthoma cells filled with electron-lucent lipid droplets of variable size. The ultrastructural characteristics of these cells enabled the distinction of two types of lipid-laden histiocytes, in relationship to the size of the lipid droplets. Since the lipid droplets were seen also in cells other than histiocytes, it appears that these changes are secondary to a common mechanism, comprising factors such as obstruction, hemorrhage, inflammation, and local hypoxia.

The impact of patient delay and physician delay on the outcome of laparoscopic cholecystectomy for acute cholecystitis

BACKGROUND

Laparoscopic cholecystectomy is now used in the management of acute cholecystitis. Under these circumstances unfavorable conditions may result in conversion and complications. Information about these conditions may help in planning the laparoscopic approach or in proceeding directly to open cholecystectomy. This study was initiated to evaluate perioperative factors associated with conversion and complications of laparoscopic cholecystectomy in acute cholecystitis. Special attention was paid to the duration of complaints until surgery, to the delay on the part of the patient, and to the delay on the part of the physician.

METHODS

Between January 1994 and December 1997, we attempted to perform laparoscopic cholecystectomy on 348 patients with acute cholecystitis. All perioperative data were collected on standardized forms.

RESULTS

There were 182 cases (52%) of acute uncomplicated cholecystitis, 90 (26%) of gangrenous cholecystitis, 33 of hydrops (9.5%), and 43 of empyema of the gallbladder (12.5%). Seventy six patients (22%) needed conversion to open cholecystectomy and complications occurred in 57 cases. Advanced cholecystitis was associated with significant patient delay (P = 0.01), and it had a significantly higher conversion rate (39%) compared with early cholecystitis (14.5%); (P <0.00001). Conversion rates were also associated with male gender (P = 0.0017), a history of biliary disease (P = 0.0085), and a patient delay of >48 hours (P = 0.028). The total and infectious complication rates were associated with an age older than 60 years (P = 0.023 and 0.007, respectively) and male gender (P = 0.026 and 0.014, respectively).

CONCLUSIONS

In acute cholecystitis, patient delay is associated with a high conversion rate. Early timing of laparoscopic cholecystectomy tends to reduce the conversion rate, as well as the total and the infectious complication rates. Male gender, a history of biliary disease, and advanced cholecystitis are associated with conversion. Male and older patients are associated with a high total and infectious complication rates.

Laparoscopic splenopexy of a wandering spleen

A laparoscopic technique for splenopexy of a wandering spleen using an absorbable mesh in an adult woman is described for the first time. This patient was referred to surgery because of recurrent biliary colic secondary to cholecystolithiasis. The wandering spleen had been diagnosed at least 4 years earlier, but a conservative approach had been adopted for a symptomless patient. Laparoscopic cholecystectomy was performed concomitantly with splenopexy. Laparoscopic splenopexy seems a feasible and safe procedure, especially when performed by experienced laparoscopic surgeons.

Laparoscopic repair of paracolostomy hernia

Paracolostomy hernia is a common complication of stoma creation. Operative repair is indicated in about 15% of cases, through several surgical approaches. We describe a laparoscopic technique used to repair a large symptomatic paracolostomy hernia in a 69-year-old woman almost 20 years after abdominoperineal resection. The laparoscopic approach to such a hernia is feasible, safe, and logical, as it combines the advantages of mesh reinforcement with those of endoscopic repair.

Neuropeptide content of peripheral nerve in relation to nerve function in neuropathy

OBJECTIVE

In this study an APAAP (alcalic-phophatase-anti-alcalic-phosphatase) technique was used to distinguish afferent (calcitonin-gene-related-peptide (CGRP) or substance-P-(SP) positive) and autonomic (tyrosin-hydroxylase (TH), neuropeptide Y (NPY) or vasoactive-intestinal-polypeptide- (VIP) positive) nerve fibers in sural nerve biopsy material from patients with moderate sensory neuropathy. A panneuronal marker against protein-gene-product 9.5 (PGP 9.5) was used for detection of the total amount of nerve fibers. Second aim was to analyze possible correlations between the impairment in tests for the function of unmyelinated fibers (i.e. thermal threshold testings, sensitivity to painful mechanical stimulation, axon reflex-mediated flare reaction and sudomotor activity) and nerve pathology.

RESULTS

A high correlation between CGRP and SP (p < 0.00003) and between TH and NPY, respectively, (p < 0.004) was found, but not between afferent and autonomic markers or between specific markers and PGP 9.5. While no correlations between sensory neuropeptides (CGRP and SP) and specific testings of afferent fiber function or between neuropeptide content and clinical data could be demonstrated, there was a significant correlation between the TH content of the sural nerve and the sweat output, stimulated by acetylcholine iontophoresis at the level of the foot (p = 0.019) and upper leg (p = 0.011).

CONCLUSION

This study demonstrates the possibility of visualizing subgroups of unmyelinated nerve fibers in sural nerve biopsies selectively with this technique. The density of TH-positive sympathetic nerve fibers, but not the density of afferent c-fibers, is correlated with corresponding results in specific tests of c-fiber function.

Use of endoscopic trocar-cannula for chest drain insertion in trauma patients and others

BACKGROUND

The insertion of a chest drain into the pleural space is a common procedure used for treatment in various intrathoracic abnormalities. Recently, a new technique for chest-tube insertion for pleural cavity drainage, using the disposable endoscopic trocar-cannula, was described for the treatment of some pathologic conditions.

METHODS

In a prospective study, we used this technique in the treatment of patients with chest trauma, spontaneous and iatrogenic pneumothorax, and various kinds of pleural effusion.

RESULTS

One hundred twelve patients were treated by using the endoscopic trocar-cannula for tube insertion into the pleural cavity. Among them, 39 patients were treated after blunt and penetrating chest trauma. Most cannulae were of 10 to 11 mm in diameter, which enabled the insertion of large-bore drain tubes. In five trauma patients, chest-tube insertion was done successfully without antecedent chest x-ray films. The complication rate was 0.89% for intrapulmonary positioning of a chest tube in a patient who had previous ipsilateral thoracic surgery.

CONCLUSION

The use of endoscopic trocar-cannulae for chest-tube insertion is a safe, simple, and effective technique for management of trauma and other diverse intrathoracic abnormalities. Its use outside the hospital should be further studied.

Low-grade B cell lymphoma of mucosa-associated lymphoid tissue (MALT) arising in the gallbladder

Mucosa-associated lymphoid tissue (MALT) lymphomas arise in most cases in the gastrointestinal tract, and are usually of low-grade B cell origin. MALT lymphomas may rarely occur in organs where lymphoid tissue is sparse, especially following inflammatory conditions. Primary lymphomas of the gallbladder are extremely rare, and MALT lymphoma has been reported only twice. We herein describe the third case of low-grade MALT lymphoma of the gallbladder, which exhibits an unusual clinical behavior. The exceptionally advanced stage of the disease stresses the importance of early operation when cholecystectomy is indicated.

A simplified laparoscopic technique for mesh placement in ventral hernia repair

The use of a large synthetic mesh for laparoscopic repair of significant ventral abdominal wall defects may be accompanied by technical difficulties resulting from improper orientation and positioning of the mesh over the defect. We suggest a technique based on initial fixation of the mesh center to the central point of the defect, and subsequent centrifugal attachment of the mesh to the abdominal wall. This technique is advantageous because it leads to precise orientation and positioning of the synthetic patch and to significant reduction of the time needed for its reinforcement over and around the defect.

[Structure quality in outpatient care of chronic pain patients]

BACKGROUND

Outcome quality of medical treatment depends on structure quality of the treatment facility. In the present study we tried evaluate structural parameters of outpatient treatment facilities relating to management of headache, low back pain and cancer pain.

METHODS

109 outpatient treatment facilities (104 offices, 3 outpatient departments of hospitals, 2 pain ambulances of hospitals) in middle franconia, one of the larger Bavarian administrative division (population: 1,6 Mio.), have been evaluated by questionnaires. Questions examined certain structural conditions of the treatment facility as compared to german guidelines for outpatient treatment of pain patients ("Schmerztherapievereinbarung").

RESULTS

Only one treatment facility worked within an interdisciplinary setting. Less than 25% (median) of total patients of an outpatient treatment facility suffered from acute or chronic headache, low back pain or cancer pain. 38% of physicians participated regularly on pain conferences. Established methods for diagnosis and documentation of patients suffering from chronic headache, chronic back pain and cancer pain were regularly used by 16%, 12% and 10% of physicians, respectively. Regular interdisciplinary cooperation in the management of patients with chronic headache, chronic back pain and cancer pain was indicated by 28%, 24% and 41% of physicians, respectively. However, personal discussion of patient related problems took place in less than 5% of physicians. Although a considerable number of different therapies (included as standard therapy for outpatient management of chronic pain in the "Schmerztherapievereinbarung") can be applied in each outpatient treatment facility (median:5), psychological therapy for management of chronic headache, chronic back pain and cancer pain was used regularly by 5%, 2% and 7% of physicians, respectively. Scoring of all examined structural parameters provides a measure for the quality of the parameters of a certain outpatient treatment facility as compared to that of an optimal outpatient facility for pain treatment (quality score=100%). However, 75% of examined outpatient treatment facilities reached quality scores only up to 43%.

CONCLUSIONS

There are considerable structural deficits in outpatient treatment facilities involved in management of patients suffering from chronic headache, chronic back pain and cancer pain. Realisation of standards according to the "Schmerztherapievereinbarung" needs organisation of an interdisciplinary network between the different specialties necessary for pain management. Interdisciplinary cooperation should be supported by the official organization of the medical self-government in Germany--the Kassenärztliche Vereinigung--which has to assure optimal conditions for outpatient treatments.

Laparoscopic approach to hydatid liver cysts. Is it logical? Physical, experimental, and practical aspects

BACKGROUND

In recent years attempts have been made to treat hydatid liver cysts laparoscopically. The purpose of this study was to evaluate different aspects of this approach and to examine whether a reasonable model could be developed.

METHODS

Three different subjects were analyzed. In the first, physical aspects related to transmembrane pressures were analyzed to demonstrate that evacuation of the cyst under pneumoperitoneum does not carry increased risk of spillage, and may even offer an advantage when the proper technique is used. In the second subject, an isolated liver model of a goat was used to study several techniques for evacuating hydatid cysts without spillage. This was tested qualitatively by demonstrating scolices in the fluid medium around the isolated liver after surgical manipulations. In the third subject, the implication of the technique was evaluated in human patients.

RESULTS

According to basic physical assumptions, the following conclusions were reached: (1) The increase in intracystic pressure is equal to or less than the increase in intraperitoneal pressure after pneumoperitoneum. (2) Aspiration of parasitic cysts by laparoscopic needle through a large cannula under "vacuum" or by sealing the cannula and adhering it to the liver by cyanoacrylate or fibrin glue was found to be very safe. Simple needle aspiration failed to prevent spillage. (3) A new transparent cannula 18 mm in diameter with a beveled tip was designed that enables good accessibility to liver cysts and safe evacuation even of huge and complex cysts.

CONCLUSIONS

The novel technique to manage hydatid liver cysts, described in the study, is feasible, sensible, and safe. The isolated goat liver containing hydatid cysts can be used as a reliable animal model to test new techniques in the future.

Effects of antihyperalgesic drugs on experimentally induced hyperalgesia in man

In a double-blind, cross-over study, ibuprofen (600 mg), a peripherally-acting selective kappa-opioid receptor agonist (7.5 mg), or placebo were given orally in experiments on healthy volunteers 1 h before assessment of pain thresholds to radiant heat and of pain ratings to controlled mechanical impact stimuli. Mechanical and thermal hyperalgesia had been induced 24 h before by irradiating skin patches on the ventral side of the upper leg. UVB irradiation induced mechanical and thermal hyperalgesia at radiation dosages of three times the minimal erythema dose. UVA irradiation resulted in an immediate erythema and a delayed tanning of the skin, however, no hyperalgesia was observed. For comparison another model of mechanical hyperalgesia was applied in the same experiments which has been previously proven sensitive to non-steroidal anti-inflammatory drugs (NSAIDs). In this model hyperalgesia was assessed, which develops during repetitive pinching of skin folds (pinch model). Ibuprofen significantly diminished heat and mechanical hyperalgesia induced by UVB, but had no effect on pain responses obtained from untreated skin. It also had an antihyperalgesic effect in the pinch stimulus paradigm. In contrast, the kappa-agonist showed no antihyperalgesic efficacy in the chosen models. It is concluded that the UVB model, as the pinch model, is suitable for establishing antihyperalgesic effects of NSAIDs, but probably not of kappa-receptor agonists, in healthy human volunteers. Compared to the pinch stimulus model, the UVB model offers additional advantages: (a) drugs may be tested after induction of the skin trauma by UV and this situation is more similar to the clinical use of antihyperalgesic drugs. (b) Since mechanical and thermal hyperalgesia is induced by UVB, drug effects can be tested upon both forms of hyperalgesia.

Laparoscopic cholecystectomy for acute cholecystitis performed by residents in surgery: a risk factor for conversion to open laparotomy?

Recent observations point to a seemingly high conversion rate to laparotomy in cases of laparoscopic operations for acute cholecystitis that are performed by surgical residents. The purpose of the study is to evaluate those observations. In a retrospective nonrandomized study, conducted between February 1992 and December 1997, 285 laparoscopic operations for acute cholecystitis were analyzed. Those performed by attending surgeons were compared with those performed by residents assisted by attending surgeons. Of 123 laparoscopic operations performed by laparoscopic surgeons between February 1992 and September 1995, 20.3% were converted to laparotomy, compared with 41.3% of the 29 operations performed by the residents (p < 0.017), with no increase in complication rate. Factors like male sex, duration of upper abdominal pain, and severity of the inflammatory process were not significantly different in both groups. The residents' seniority did not influence the conversion rate. A constant and significant decrease in conversion rate to laparotomy was observed over the course of time, as the study proceeded to December 31, 1997 (p < 0.01). We conclude that the performance of difficult laparoscopic cholecystectomy by residents with the assistance of attending surgeons is feasible, but carries a higher conversion rate to laparotomy for reasons that are not entirely clear. The possibility of a learning curve of the residents is suggested.

Innervation territories of single sympathetic C fibers in human skin

Microneurography techniques were used to record action potentials from unmyelinated nerve fibers (C fibers) in the cutaneous fascicles of the peroneal nerve in healthy volunteers. C units were identified by their long latency responses to electrical stimulation of their terminals in the skin. Their responsiveness to mechanical or heat stimuli applied to the skin or to sympathetic reflex provocation tests was determined by transient slowing of conduction velocity following activation (marking technique). In a sample of 381 C units, 59 were unresponsive to mechanical and thermal stimulation of their endings, but responded to sympathetic reflex provocation tests, e.g., arousal or deep inspiration. They were classified as sympathetic efferent units. On average, conduction velocities of sympathetic units were lower (0.78 +/- 0.12 m/s, mean +/- SD) than those of mechano-heat (CMH) or mechanoresponsive (CM) afferent C units (0.91 +/- 0.14 m/s). Endings of most of the sympathetic units were located in the skin of toes or in the foot dorsum. Innervation territories of 16 sympathetic units were mapped by means of conditioning transcutaneous electrical stimuli. Twelve units had one continuous skin territory, whereas two units had two and two other units had three and five separate territories, respectively. The mean innervated area was 128 mm2 (range: 24-350 mm2). Innervation territories of sympathetic units were of approximately the same size in different skin regions on the lower leg, foot, or toes. Based on responses to whole body cooling and warming, two units were tentatively classified as vasoconstrictor and sudomotor units, respectively. Eleven units were tested for responsiveness to iontophoresis of acetylcholine in their innervation territories. In five of them, activity was induced that was not due to central reflex activity but instead due to antidromic activation from the peripheral terminals. Iontophoresis of saline or histamine was ineffective. These findings confirm the existence of excitatory cholinergic receptors in the terminal membrane of some sympathetic units, possibly sudomotors.

Laparoscopic management of lumbar hernia

We describe (for the first time) a laparoscopic approach to repair an acquired superior triangle lumbar hernia in a morbidly obese woman by using prosthetic mesh. Such a technique provides an excellent anatomic view, thus avoiding injury to structures in proximity to the hernia during repair; eventually the well-known advantages of such approach result.