Magnetic resonance elastography with guided pressure waves

Magnetic resonance elastography aims to non-invasively and remotely characterize the mechanical properties of living tissues. To quantitatively and regionally map the shear viscoelastic moduli in vivo, the technique must achieve proper mechanical excitation throughout the targeted tissues. Although it is straightforward, ante manibus, in close organs such as the liver or the breast, which practitioners clinically palpate already, it is somewhat fortunately highly challenging to trick the natural protective barriers of remote organs such as the brain. So far, mechanical waves have been induced in the latter by shaking the surrounding cranial bones. Here, the skull was circumvented by guiding pressure waves inside the subject's buccal cavity so mechanical waves could propagate from within through the brainstem up to the brain. Repeatable, reproducible and robust displacement fields were recorded in phantoms and in vivo by magnetic resonance elastography with guided pressure waves such that quantitative mechanical outcomes were extracted in the human brain.     

PDT in clinics: indications, results, and markets.

Photodynamic therapy (PDT) is based on the selective light activation of an exogenously given drug to patients. PDT acts mainly on cell membranes either of neovascular endothelial cells or of cancer cells leading to cancer cell death. Six drugs are now marketed based on clinical assays in various indications, which showed a clear cost efficiency as compared to other classical procedures. PDT is easy to handle and can be performed in medical installations fitting the conditions of health care in developing countries. Its cost effectiveness could represent an appropriate solution to the increasing number of cancers of various origin. However despite all the clinical results now available, PDT development remains slow. The reasons for this situation include cost of development, intellectual property, and competition between pharmaceutical companies.     

Predictive factors of stroke in patients undergoing coronary bypass grafting: statins are protective.

BACKGROUND: Despite major improvement in surgical techniques and intensive care management, stroke remains one of the most devastating complications of coronary artery bypass grafting (CABG). We aimed to determine factors predicting the occurrence of stroke during CABG. A special interest was focused on preoperative therapies. METHODS: We prospectively enrolled 810 consecutive candidates for CABG alone in a specific database, including all pre- and perioperative data (history, clinical, therapeutic, cardiac catheterization, surgical and intensive care data). Univariate tests and then multiple logistic regression analysis were used to determine independent predictive factors. RESULTS: During the first postoperative month, stroke occurred in 11 cases and transient ischemic attack (TIA) in 4 additive cases (cumulative rate: 1.85%). After the multivariate analysis, the following factors remained significant (p<0.05) in the predictive model, with corresponding odds ratios between brackets: redo cardiac surgery (7.45), unstable cardiac status (4.74), past history of cerebrovascular disease (4.14), past history of peripheral arterial disease (3.55), whereas the presence of preoperative statins was protective (0.24, 95% IC: 0.07-0.78). The addition of perioperative data (aortic calcification, postoperative arrhythmia, on/off-pump surgery) did not change the final predictive model. CONCLUSION: To our knowledge, this is the first real-world observational report highlighting the interest of statins for the prevention of stroke in the very special situation of CABG. Even though according to randomized trials coronary patients have a benefit from these drugs, a special level of interest should be directed towards those presenting the above-mentioned risk factors.     

Working memory after severe traumatic brain injury.

The aim of the present study was to assess the functioning of the different subsystems of working memory after severe traumatic brain injury (TBI). A total of 30 patients with severe chronic TBI and 28 controls received a comprehensive assessment of working memory addressing the phonological loop (forward and backward digit span; word length and phonological similarity effects), the visuospatial sketchpad (forward and backward visual spans), and the central executive (tasks requiring simultaneous storage and processing of information, dual-task processing, working memory updating). Results showed that there were only marginal group differences regarding the functioning of the two slave systems, whereas patients with severe TBI performed significantly poorer than controls on most central executive tasks, particularly on those requiring a high level of controlled processing. These results suggest that severe TBI is associated with an impairment of executive aspects of working memory. The anatomic substrate of this impairment remains to be elucidated. It might be related to a defective activation of a distributed network, including the dorsolateral prefrontal cortex.     

What is the place of electroneuromyographic studies in the diagnosis and management of pudendal neuralgia related to entrapment syndrome?

Entrapment of the pudendal nerve may be at the origin of chronic perineal pain. This syndrome must be diagnosed because this can result in the indication of surgical decompression of the entrapped nerve for pain relief. Electroneuromyographic (ENMG) investigation is often performed in this context, based on needle electromyography and the study of sacral reflex and pudendal nerve motor latencies. The limits of ENMG investigation, owing to various pathophysiological and technical considerations, should be known. The employed techniques do not assess directly the pathophysiological mechanisms of pain but rather correlate to structural alterations of the pudendal nerve (demyelination or axonal loss). In addition, only direct or reflex motor innervation is investigated, whereas sensory nerve conduction studies should be more sensitive to detect nerve compression. Finally, ENMG cannot differentiate entrapment from other causes of pudendal nerve lesion (stretch induced by surgical procedures, obstetrical damage, chronic constipation...). Thus, perineal ENMG has a limited sensitivity and specificity in the diagnosis of pudendal nerve entrapment syndrome and does not give direct information about pain mechanisms. Pudendal neuralgia related to nerve entrapment is mainly suspected on specific clinical features and perineal ENMG examination provides additional, but no definitive clues, for the diagnosis or the localization of the site of compression. In fact, the main value of ENMG is to assess objectively pudendal motor innervation when a surgical decompression is considered. Perineal ENMG might predict the outcome of surgery but is of no value for intraoperative monitoring.     

Laparoscopic adrenalectomy: lessons learned from 100 consecutive procedures.

One hundred consecutive laparoscopic adrenal procedures for a variety of endocrine disorders were reviewed. There was no mortality, morbidity was 12%, and conversions was 3%. During follow-up, none had recurrence of hormonal excess. Laparoscopic adrenalectomy is the procedure of choice for adrenal removal except in carcinoma or masses > 15 cm. OBJECTIVE: The authors evaluate the effectiveness of laparoscopic adrenalectomy for a variety of endocrine disorders. SUMMARY BACKGROUND DATA: Since the first laparoscopic adrenalectomy was performed in 1992, this approach quickly has been adopted, and increasing numbers are being reported. However, the follow-up period has been too short to evaluate the completeness of these operations. METHODS: One hundred consecutive laparoscopic adrenal procedures from January 1992 until November 1996 were reviewed and followed for adequacy of resection. RESULTS: Eighty-eight patients underwent 97 adrenalectomies and biopsies. The mean age was 46 years (range, 17-84 years). Indications were pheochromocytomas (n = 25), aldosterone-producing adenomas (n = 21), nonfunctional adenomas (n = 20), cortisol-producing adenomas (n = 13), Cushing's disease (n = 8), and others (n = 13). Fifty-five patients had previous abdominal surgery. Mean operative time was 123 minutes (range, 80-360 minutes), and estimated blood loss was 70 mL (range, 20-1300 mL). There was no mortality, and morbidity was encountered in 12% of patients, including three patients in whom venous thrombosis developed with two sustaining pulmonary emboli. During pheochromocytoma removal, hypertension occurred in 56% of patients and hypotension in 52%. There were three conversions to open surgery. The average length of stay has decreased from 3 days (range, 2-19 days) in the first 3 years to 2.4 days (range, 1-6 days) over the past 16 months. During follow-up (range, 1-44 months), two patients had renovascular hypertension and none had recurrence of hormonal excess. CONCLUSION: Laparoscopic adrenalectomy is safe, effective, and decreases hospital stay and wound complications. Prior abdominal surgery is not a contraindication. Pheochromocytomas can be resected safely laparoscopically despite blood pressure variations. Venous thrombosis prophylaxis is mandatory. The laparoscopic approach is the procedure of choice for adrenalectomy except in the case of invasive carcinoma or masses > 15 cm.     

Major vascular injuries during gynecologic laparoscopy

Background:This study was undertaken to report our experience with major vascular injuries in gynecologic laparoscopy in order to specify the circumstances under which they occurred, the means of diagnosis, the risk factors, and the means for prevention.Study Design:Retrospective case review study.Results:Seventeen patients with 21 major vascular injuries were identified. The average age of the patients was 33.8 ± 11.6 years, and the mean body index mass was 21.6 ± 3.08 kg/m². Three of four of the accidents occurred during the set-up phase of laparoscopy (13 cases; 76.5%), and in 4 cases (23.5%) the accident occurred during the laparoscopic surgery procedure. Eleven (84.6%) of the complications occurring during the set-up phase were secondary to insertion of the umbilical trocar and 2 (15.4%) to insertion of the needle used to create the pneumoperitoneum (P-needle). Half (6 cases; 54.5%) of the major vascular injuries secondary to insertion of the umbilical trocar were observed when reusable trocars were used. In every case, the diagnosis was made during the operation. Two patients died, and two others presented a serious complication (phlebitis; acute ischemia requiring reoperation).Conclusions:Major vascular injuries are rare but serious complications of laparoscopic surgery. Prevention of these accidents relies on the surgeon’s experience and scrupulous respect of the safety rules. In the vast majority of cases, it is necessary to convert to laparotomy immediately, calling in a vascular surgeon.     

Synthesis and cytotoxic activity of new alkyl[3-(2-chloroethyl)ureido]benzene derivatives

Several alkyl[3-(2-chloroethyl)ureido] (CEU) benzene derivatives were prepared as potential anticancer agents. These new compounds were readily prepared in good yields by addition of anilines to 2-chloroethylisocyanate. Their cytotoxic activity was evaluated on human breast cancer (MDA-MB-231), human colon adenocarcinoma (LoVo) and mouse lymphocytic leukemia (P388D₁) tumor cell lines. Several new CEUs were significantly more cytotoxic than the nitrogen mustard chlorambucil. The biological activity of these aromatic urea derivatives seems to be related to the nature and position of the alkyl substituents on the aromatic ring. Substitution by branched alkyl groups on position 4 of the aromatic ring led to cytotoxic molecules which are up to 5 times more potent than the standard chlorambucil.