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The aim of this note is to investigate the assumptions and the proofs of some results by F. Hahn, which have been stated in several other classics of Economic Theory. The results deal with the relations between the gross substitutability and the weak axiom of revealed preference, in a pure exchange economy, ruled by the Walras law.

Purpose: We report our experience with the use of US and CT in postoperative complications of inguinal hernioplasty using a prosthetic polypropylene mesh., Materials and Methods: This study was divided into two parts. In the first we evaluated the in-vitro sonographic and CT appearance of a fragment of prosthetic mesh. In the second, we retrospectively reviewed the imaging findings in 31 patients (aged 42 to 75 years) examined after inguinal hernia repair between December 2000 and December 2002. Seventeen hernias had been repaired with a laparoscopic approach, and the others with the anterior tension-free technique proposed by Lichtenstein (12 cases) and Trabucco (2 cases). Sonography was performed to assess suspected complications between the second and the fourth postoperative day. Both high-resolution 7.5-10 MHz linear transducers and a 3.5 MHz convex probe were employed to ensure complete evaluation of superficial and deep structures. Eight obese patients also underwent CT for confirmation of the US results., Results: At sonography the prosthetic mesh appeared as a linear hyperechoic image measuring about 2 mm in thickness, with posterior acoustic shadow and a finely irregular surface. Only one of the 17 patients examined after laparoscopic inguinal hernioplasty had a seroma; in the other 14 repaired with the anterior tension-free technique we identified 2 abscesses, 3 seromas, 2 "foldings" of the prosthetic mesh, and 2 mesh displacements with associated recurrence of hernia. CT confirmed the US results as to the presence of fluid collections, and visualised the prosthetic mesh in only 2/8 cases., Conclusions: Sonography is a useful means of assessing postoperative changes in laparoscopic and in anterior tension-free hernia repair. It can differentiate these complications from recurrences of hernia. Colour-Doppler US can also correctly detect normal blood flow of the testes. Sonography is the only technique that can easily demonstrate the prosthetic mesh in the abdominal wall.

Purpose: Metastatic recurrence in the abdominal wall surgical scar is not uncommon. Our aim was to evaluate the role of ultrasonography (US), computed tomography (CT) and percutaneous fine needle aspiration biopsy in the diagnosis of metastatic recurrence along the surgical scar., Materials and Methods: We evaluated 17 nodules in the surgical scar, either single (n=9 patients) or multiple (n=2 patients), in 11 patients operated on for known abdominal neoplasm confirmed by histology. The most common primary tumour was colonic carcinoma. All patients had undergone open surgery, and the lesions were detected at routine follow-up or at diagnostic examinations performed for clinical suspicion of recurrence. Ultrasonography (7.5-10/10-13 MHz) and fine needle biopsy were performed in all cases; contrast-enhanced CT was carried out in 10 patients. All lesions underwent histopathological examination., Results: The histological findings showed 16/17 metastatic nodules and one suture granuloma. Lesions had variable size (15-55 mm), roundish shape, ill-defined margins (60% cases) and hypoechoic solid echotexture. All were characterised by marked contrast medium uptake on CT examination. US-guided aspiration biopsy precisely defined the metastatic nature of the nodules in 16/17 cases. In the patient with suture granuloma, both CT and US findings suggested malignancy; however, cytology showed only scant fibrous material. The anterior abdominal wall was the most common site of metastatic disease (14 lesions)., Conclusions: US enables an accurate detection and diagnosis of metastatic nodules along the surgical scar. Fine needle aspiration biopsy represents, in our opinion, the most suitable procedure for providing an accurate diagnosis of this condition.

Purpose: To report the various US patterns of the diaphragmatic crura and the changes occurring during the different phases of respirations. The diaphragm has two US patterns: the central membranous part appears highly reflective while the posterior, upper and lateral muscular portions are hypoechoic and thick. The crura can sometimes appear quite bulky, which appearance is easy to misinterpret., Material and Methods: We carried out a three-stage work: first we reviewed the US examinations of 23 subjects with a nodular appearance of the posteromedial bundles and studied the changes in thickness during respiration. Second we studied the diaphragmatic crura in 30 subjects aged 18-71 years, 15 men and 15 women. We used a commercially available unit with sector and convex 3.5 MHz probes at baseline and during breath hold and acquired multiple parasagittal and transverse scans. The crura thickness was measured in all patients. Last, we studied the diaphragmatic regions of 10 patients with right pleural effusion and of 8 patients with associated ascites and pleural effusion using 2.0-5.0 MHz convex phased-array transducers., Results: We found focal thickening of the crura in 11 of 23 patients with US findings of diaphragmatic nodules, but only in deep inspiration. The thickening was 1.5-2.2 cm long and maximum thickness was 10 mm. In the other 12 subjects we found 9 small lobules in the right and 3 in the left crus. In the anatomic study, we observed a 3-band appearance of the diaphragmatic crura, probably referable to muscle bundles, in 30 subjects on sagittal images, in 12 on coronal images and in 28 on anterior transverse images. The diaphragmatic crura were identified in 26 subjects only. The left posterior crus was identified in 29 subjects on left coronal images and in 15 on anterior transverse images; it was demonstrated on anterior sagittal images in close proximity to the aorta in only 4 subjects. Right crus thickness, measured on sagittal scans, ranged 3-10 mm in deep inspiration and 1-4 mm in expiration while the left crus was 3-6 mm in inspiration and 1-2 mm in expiration. The length of the right crus, studied in the preaortic portion, ranged from 7 cm in deep inspiration to 9.7 cm in expiration while the left one was 6.5 to 8.8 cm. The right lateral diaphragmatic bundles were seen in 28 subjects only on repeated subcostal oblique scans and the the left ones in 11 subjects only. Finally the thin anterior bundles were shown on parasagittal images in 13 cases in the right side and in 2 in the left. A 2-band appearance of the diaphragm was seen in 10 patients with pleural effusion and in 8 patients with associated ascites. A single band was found only in the tendinous portion of the diaphragm., Discussion and Conclusions: US is presently considered the imaging method of choice in the assessment of changes in thickness and length of the diaphragmatic crura. These structures have different US patterns and can sometimes appear quite bulky and thus be easily mistaken for other anatomic or abnormal structures; orthogonal scans may be required for the differential diagnosis.

Background: The use of percutaneous ultrasound-directed radiofrequency is a recent technique in non-surgical therapy of some neoplastic liver lesions. Purpose of this study is to demonstrate that the use of a narcosis-free analgesia allows to perform this procedure, which is generally painful and badly by the patient., Methods: We treated 51 patients for a total of 126 procedures; the first 17 patients underwent a mono- or multipolar technique with uncooled electrodes, while the remaining 34 patients have been treated with double perfusion lumen electrodes with the chance of tipcooling. We used diidrobenzoperydol and fentanyl with a mean dose for each session of 209 micrograms for the first 17 patients and 109 micrograms for the other 34., Results: Using VAS, we obtained a painless procedure in 42 patients and mild-pain sensations in 9 patients, while one hour after the procedure painless or light-pain sensation were observed in 49 patients and mild-pain in 2 patients, which required the use of FANS i.v. At discharge, all patients were pain-free or with very light pain sensation. We reduced the intra-hospital observation of patients from 5 to 3 hours, once the technique has been modified. 4 patients complained about nausea and 1 of these emesis. We did not observe any cardiovascular, respiratory and/or neurological complications., Conclusions: The use of neuroleptanalgesia allowed us to perform the described procedure with a good feeling by the patients.

One-hundred-eighty patients underwent emergency minimally invasive procedures (laparo and thoracoscopy) in the last two years. In twelve postoperative drawbacks another surgical procedure was performed. Laparoscopic or thoracoscopic exploration was undertaken in 8 cases while open surgery was done in 4. Complications and surgical overtiming rate was higher after endoscopic than open surgery. This approach allows us to correct very few and selected disease when a skilled surgical team is available especially during reoperations.

In the last three years (1992-1995) 130 stab (114) and gunshot (16) wounds were observed at and admitted to the Emergency Surgical Department of Fatebenefratelli Hospital of Milan. We observed a high incidence of non-EEC patients (62%). Imaging devices (US and CT scan) and surgical minimally invasive procedures have reduced open surgery rate with a remarkable reduction in drawbacks and mortality.

To assess the efficacy of a new US contrast agent [SH U 508 A (Levovist), Schering] in evaluating hepatocellular carcinoma (HCC) vascularization, 38 patients with 43 lesions were submitted to color Doppler US before and after i.v. contrast medium administration. Four patients were studied after arterial chemoembolization. The patients had been selected on the basis of suboptimal color Doppler signals on baseline images. Each patient received two to four injections of Levovist in standard doses. Tumor vascularization was qualitatively graded on a 0-3 scale. Twelve tumors (27.9%) appeared avascular at baseline examinations, while 31 (72.1%) exhibited low to moderate flow signals. After contrast agent administration, color Doppler signals were markedly enhanced in 35/43 lesions (81.4%), lasting 40 to 240 seconds. The lack of enhancement was related to tumor hypovascularity (necrosis at CT), portal vein thrombosis, deep location and successful chemoembolization. The detection of flow signals in chemoembolized tumors was explained by the persistence of viable tumor tissue. After Levovist administration, flow signals were detectable in 97.6% of the HCCs. Therefore, Levovist proved to be an effective tool for color Doppler evaluation of HCC vascularization.

It is well known that artifacts can be observed during US examinations; the same is true also for Doppler and color-Doppler images of blood flow. Recognizing these artifacts is important to avoid image misinterpretations and, when possible, to overcome them by modifying either techniques or unit settings, or both. This work was aimed at presenting the several artifacts which can be observed during Doppler investigations, at classifying them, and trying to understand the physical and/or technical principles underlying their origin. Doppler and color-Doppler artifacts can be divided into four large groups: 1) artifacts regarding evaluation of the presence of flow; 2) artifacts regarding evaluation of the direction of flow; 3) artifacts regarding determination of the velocity of flow; 4) artifacts affecting spatial location, on the screen, of the examined vessel. Each of the above can cause severe diagnostic misinterpretations, if not correctly recognized and interpreted. It must be kept in mind that an accurate analysis of unit settings during scanning, and the meticulous evaluation of the obtained color images are of the utmost importance for the proper use of this valuable but difficult diagnostic technique.

It is well known that angiotensin antagonists cause increase of renal blood flow. We have examined, using duplex Doppler sonography, the changes of renal blood flow velocity induced by oral administration of 50 mg. of Captopril. We examined 19 kidneys in 17 subjects without hypertension. Both peak systolic and diastolic velocities were measured at renal hilum and at arcuate arteries, and the resistive index (RI) was calculated. In conclusion duplex Doppler sonography shows significant increase of blood flow velocities both at the hilum and at the arcuate arteries, without variation of the RI, thus showing that changes affect the whole Doppler wave, both in systole and diastole.

The Authors describe their reconstruction technique after a "step" gastric resection for peptic or neoplastic pathology. The use of staplers such as TA 30 or GIA for the duodenum is reported. After skeletonizing the lesser curve up to the cardias by sectioning the left gastric artery at its origin and up to the penultimate short vessel on the greater curve, the stomach is resected distally to this two points using a TA90 staplers. So it is possible to remove the greater part of the acid-secreting area in order to avoid ulcers of the anastomosis or of the gastric stump, and also to achieve a complete lymphadenectomy in case of neoplasm. Then a Roux-en-Y gastro-jejunal anastomosis is performed using an EEA28 circular stapler. The jejunal stump is closed with a TA30. Finally, a manual jejuno-jejunal anastomosis is made at least at 50 cm from the previous one. From November 1987 to January 1989, 13 patients were operated: 9 for peptic ulcer and 4 for antrum neoplasms. There were no complications during and after the operations. Mortality was 0%. The patient, usually starts eating on the 6th or 7th day after operation, and is discharged on the 10th day. After 6 months an EGD scopy is required: the 8 performed till now have demonstrated excellent anastomosis and no peptic lesions. Scintigraphic evaluations and pH monitoring are still in course to define the gastric stump acid secretion and the absence of biliary reflux.

Prompted by several cases of barium peritonitis of their own observation, the authors review the literature on the subject and outline the more common etiopathogenetic factors involved and gross and histological aspects of the disorders. After describing their own four cases of barium peritonitis, the authors outline some basic principles for the prevention and treatment of this rare complication.

Ten cases of abdominal internal hernia observed at the Niguarda Hospital Emergency Surgery Division, Milan, during the period 1969-1978 are described. Even though it is extremely uncommon, this form must be kept in mind in the course of differential diagnosis when the picture includes: typical and striking symptoms of ileal strangulation, radiographical evidence of marked distension of the ileal loops with hydro-air levels, and a negative history of abdominal surgery.

Some observations have been made on inferior olive specimens in the adult cat, with aldehydes fixation techniques through vascular perfusion suitable for electron microscropy. The results made it possible to recognise five types of vesicular structures present in different nerve endings (differences either in type or in number). A possible topographic organization of synaptic connections, between the afferent endings and the dendritic structures of the inferior olive has been considered and it seems that on every large dendrite, nearer the cell body, there is a development of numerous connection. As such connections give a great deal of information to the dendrites with much much interaction it seems possible that there is modulation in the activation of the postsynaptic element. On the other hand, in the periphery of the dendritic branch, many thin branches seem to make contact with few and large endings; this leads us to believe that the regulations of the information is not based only on the afferences but mainly on distribution, origin and number of the postsynaptic elements. A study of the interdendritic connections and of tubulo-vesicular structures showed that their diameter and dense content have a similar morphology with the big granulated vesicles, visible in the terminals, or along the fibres or, frequently, in the Golgi apparatus.

The authors describe a truly uncommon case of internal abdominal hernia attributable to malformation of the falciform ligament. The patient, a man aged 26, had complained in the past of cramping pain in the epigastric region, usually occurring after meals and sometimes ending with vomiting of ingested food; but all diagnostic methods and procedures had consistently ruled out any extant pathology of the stomach, duodenum, biliary tract, or pancreas. Present hospitalization was justified by a clinical picture suggesting peritonitis from perforated gastric or duodenal ulcer. At operation the authors found a strangulated loop of small intestine following left-to-right migration through a hole in the falciform ligament of the liver. In the authors' interpretation the background cause of the trouble was incomplete development of the falciform ligament, and the immediate cause of the acute episode was abnormal motility and exaggerated peristalsis of the ileum, possibly due to the presence of a diverticulum; the latter two conditions are invoked as a possible explanation for the repeated episodes of abdominal pain in the patient's history.

Twenty-five patients suffering from chronic renal insufficiency and who had been undergoing dialysis for a long time were tested on the Wechsler-Bellevue Intelligence Scale with a control of twenty-five subjects of the same age with a comparable educational and social background. The results of the statistical analysis of the difference between the two groups demonstrates a significant psychological deterioration in the group of uremic patients which was particularly noticeable in the performance test. The rate of deterioration was not significantly related to the duration of the dialysis. At the same time electromyography (motor conduction velocity of the S.P.E. nerve) show in 40% of the uremic patients evidence of neuropathy.