Minimally invasive retropleural approach for central thoracic disc herniation.

BACKGROUND: The management of symptomatic thoracic disc herniation (TDH) has evolved tremendously ever since the first laminectomy was performed. The last decade has witnessed the evolution of minimally invasive approaches for TDH most of which have been posterior/posterolateral. Traditional anterior approaches involve a thoracotomy or more recently, thoracoscopic techniques. The authors describe a less invasive anterior retropleural surgical approach to address central thoracic disk herniations which is less extensive than a thoracotomy and allows better anterior access than posterior or posterolateral approaches. The retropleural approach allows the use of the operative microscope with a tubular retractor in the anterior thoracic spine. MATERIAL AND METHODS: 7 patients with central disc herniation who were managed with the minimally invasive lateral retropleural approach from 2007-2010 at our institution were included in the study. Surgical technique consisted of a lateral position followed by retro-pleural exposure through tubular retractor system without the need of intraoperative lung collapse. Clinical details including age, sex, clinical presentation, surgical details, complications and outcome at last follow-up were analyzed. RESULTS: Patients age ranged in age from 30 to 70 years (mean: 52 years). The duration of symptoms ranged from 4 days to 3 years. All patients presented with thoracic myleopathy on physical examination. The average length of stay in the hospital was 2.6 days (range: 1-4 days). Follow-up was available for all the patients. Myelopathy was assessed by the Nurick scale. On examination, 3 of 7 patients improved by one point on the Nurick scale. No patient deteriorated after surgery. There were no complications related to the approach. CONCLUSIONS: A minimally invasive retropleural approach using tubular retractor system for central thoracic disc herniation is feasible and may be a less invasive anterior alternative to a thoracotomy.

In-utero evaluation of the fetal umbilical-portal venous system: two- and three-dimensional ultrasonic study.

OBJECTIVES: To describe the normal anatomy of the fetal umbilical-portal venous system (UPVS) and to assess possible anatomical variants of the main portal vein (MPV) insertion into the portal sinus (PS). METHODS: This was a prospective cross-sectional study of low-risk patients between 14 and 36 weeks of gestation. Two- (2D) and three-dimensional (3D) ultrasound techniques combined with color and high-definition flow Doppler were used to evaluate the fetal UPVS. The standard transverse plane of the fetal upper abdomen, used for measuring the abdominal circumference, was taken in all cases as the point of reference. A longitudinal section was taken to identify the normal course of the umbilical vein and ductus venosus (DV). We performed offline analysis of all gray-scale and color Doppler 2D and 3D volume datasets. RESULTS: Two hundred and eight fetuses were included in the study. The umbilical vein was observed to course in a cephalad direction from its entry point into the fetal abdomen, joining the L-shaped PS, a confluence of vessels that is the main segment of the left portal vein (LPV). Three branches emerge from the LPV: two to the left, the inferior and superior branches, and one to the right, the medial branch. The main LPV then courses abruptly to the right. Following the emergence of the DV, the communication of the MPV with the LPV marks the point at which the vessel becomes the right portal vein (RPV), giving rise to its anterior and posterior branches. We were able to define three main variants of connection between the MPV and the PS. In 140 (67.3%) fetuses the MPV was connected to the LPV in an end-to-side T-shaped anastomosis, in 26 (12.5%) fetuses the MPV connected with a side-to-side X-shaped anastomosis and in 30 (14.4%) fetuses the two vessels ran in parallel with a short communicating segment, in an H-shaped anastomosis. In the remaining 12 (5.7%) cases classification into one of these three groups was not possible due to intermediate morphology. CONCLUSIONS: Knowing the normal anatomy of the UPVS and being aware of the possible variants of the connection between the MPV and the PS is a fundamental requirement for accurate prenatal diagnosis of the anomalies of the fetal UPVS.

Surface states and the charge of a dust particle in a plasma.

We investigate electron and ion surface states of a negatively charged dust particle in a gas discharge and identify the charge of the particle with the electron surface density bound in the polarization-induced short-range part of the particle potential. On that scale, ions do not affect the charge. They are trapped in the shallow states of the Coulomb tail of the potential and act only as screening charges. Using orbital-motion limited electron charging fluxes and the particle temperature as an adjustable parameter, we obtain excellent agreement with experimental data.

Electron-impact ionization of silicon tetrachloride (SiCl4).

We measured absolute partial cross sections for the formation of various singly charged and doubly charged positive ions produced by electron impact on silicon tetrachloride (SiCl4) using two different experimental techniques, a time-of-flight mass spectrometer (TOF-MS) and a fast-neutral-beam apparatus. The energy range covered was from the threshold to 900 eV in the TOF-MS and to 200 eV in the fast-neutral-beam apparatus. The results obtained by the two different experimental techniques were found to agree very well (better than their combined margins of error). The SiCl3(+) fragment ion has the largest partial ionization cross section with a maximum value of slightly above 6x10(-20) m2 at about 100 eV. The cross sections for the formation of SiCl4(+), SiCl+, and Cl+ have maximum values around 4x10(-20) m2. Some of the cross-section curves exhibit an unusual energy dependence with a pronounced low-energy maximum at an energy around 30 eV followed by a broad second maximum at around 100 eV. This is similar to what has been observed by us earlier for another Cl-containing molecule, TiCl4 [R. Basner, M. Schmidt, V. Tamovsky, H. Deutsch, and K. Becker, Thin Solid Films 374 291 (2000)]. The maximum cross-section values for the formation of the doubly charged ions, with the exception of SiCl3(++), are 0.05x10(-20) m2 or less. The experimentally determined total single ionization cross section of SiCl4 is compared with the results of semiempirical calculations.

Prenatal manifestation of superior mesenteric artery syndrome.

Intestinal obstruction is not a rarity in the newborn. Its etiology is diverse. Superior mesenteric artery syndrome (SMAS) is a phenomenon in which the duodenum is obstructed by the SMA. This causes bowel obstruction accompanied by duodenal dilatation. It has previously been described in adults and children but rarely in infants. We report for the first time on an intrauterine manifestation of SMAS.

Endoscopic approach for carotid artery surgery.

BACKGROUND: Although recent advances in the treatment of carotid artery stenosis have included endovascular angioplasty and stent placement, carotid endarterectomy is still the approach of choice for carotid disease and is one of the most commonly performed operations today. Minimally invasive surgeries involving the neck have recently been performed for thyroid and parathyroid diseases. The purpose of this study was to evaluate the feasibility of an endoscopic approach for carotid artery surgery in a large animal model. METHODS: Eight 25- to 30-kg pigs were used. Animals underwent endoscopic carotid dissection with carbon dioxide insufflation at 10 mmHg. A 1.5- to 2-cm arteriotomy was made in the common carotid artery. Four animals underwent direct arteriotomy closure, and four animals underwent synthetic patch graft placement using intracorporeal suturing techniques. Open examination of the operative site and carotid angiograms were performed at the end of the procedure. Operative time was recorded in the last four cases. RESULTS: All animals tolerated the procedure well and carotid artery repair was successfully performed in all cases using a four-trocar technique. The entire extent of the cervical common and internal carotid arteries was exposed up to the cranial base. Cranial nerves and cervical structures were clearly visualized and preserved. No bleeding occurred at the end of the procedure. Carotid angiograms confirmed patent, nonstenotic vessels in all cases. CONCLUSION: Endoscopic approach for carotid surgery is technically feasible in the porcine model. This approach may represent a valuable option for surgery of the carotid artery since it offers the advantages of minimally invasive techniques while maintaining the benefits of surgical arterial repair.

Biochemical and behavioral characterization of novel methylphenidate analogs.

As part of a project to develop treatment agents for cocaine abuse, (+/-)-threo-methylphenidate (TMP) and 11 analogs were characterized biochemically and behaviorally to assess their potential as anti-cocaine medications. The compounds contained aryl and/or nitrogen substitutions, and/or replacement of the ester function by an alcohol or ether. All of the analogs, except for the N-methyl-substituted compounds, showed increased inhibitory potency against (3)H-(-)-2-beta-carbomethoxy-3-beta-(4-fluorophenyl)tropane 1,5-naphthalenedisulfonate ([(3)H]WIN 35,428) ([(3)H]WIN) binding to the dopamine transporter, compared with TMP. In general, parallel results were obtained for inhibition of [(3)H]dopamine ([(3)H]DA) uptake. Although compounds with N-substitutions were proportionally less potent at blocking DA uptake than WIN binding (compared with the unsubstituted compounds), one such compound that was 6-fold more potent against [(3)H]WIN binding than [(3)H]DA uptake did not attenuate inhibition by cocaine of synaptosomal [(3)H]DA transport. The compounds were significantly less potent in displacing [(3)H]citalopram binding from the serotonin transporter. In cocaine discrimination studies in rats, all but two of the analogs (both N-substituted) completely generalized with the cocaine stimulus. Robust positive correlations were observed between potency in the drug discrimination assay and activity at the dopamine transporter, but not the serotonin transporter. When tested for their ability to alter cocaine discrimination, four of the analogs (three of which had N-substitutions and shallow dose-response curves as cocaine substitutes) actually enhanced cocaine discrimination, often at combined doses of cocaine and test compound that were inactive when given separately. Taken together, the results suggest that TMP analogs may have potential as substitution therapies for the treatment of cocaine abuse.

Pediatric intramedullary spinal cavernous malformations.

STUDY DESIGN: A retrospective analysis of a large single institution pediatric intramedullary tumor database. The database was searched for all pediatric intramedullary cavernous malformations. OBJECTIVES: To review the authors' experience with three pediatric intramedullary cavernous malformations, review the previous literature, and discuss the surgical management for these rare lesions. SUMMARY OF BACKGROUND DATA: Cavernous malformations can occur throughout the central nervous system; however, the intramedullary spinal cord is a rare location. More recent estimates indicate that cavernous malformations constitute 5% of all vascular malformations. There is no series that reports the management of pediatric intramedullary cavernous malformations. METHODS: There were 181 pediatric intramedullary lesions in the tumor database. A review revealed three children with a mean age of 13.3 years (range, 8-19 years) with intramedullary cavernous malformations. All these children presented with an acute motor deficit that prompted radiographic imaging and diagnosis. All the children underwent laminectomy and gross total removal of the lesion. All the malformations abutted the dorsal pial surface and created a blue discoloration, which was evident after opening the dura. RESULTS: Approximately 10% of all intramedullary cavernous malformations present in the pediatric population. Pediatric lesions, unlike those in adults, have an acute presentation, and the lesions are typically found in the cervical region. The surgical removal of these malformations results in a good functional outcome. The entire neuraxis should be screened because there is a high incidence of multiple lesions. CONCLUSIONS: The surgical removal of these malformations results in a good functional outcome. The entire neuraxis should be screened because there is a high incidence of multiple lesions.

[Transcatheter closure of atrial septal defects in adults. Practicality and safety of four different closure systems used in 102 patients]. / Katheterinterventioneller Verschluss von Vorhofseptumdefekten im Erwachsenenalter. Durchführbarkeit und Sicherheit bei 102 Patienten unter Verwendung vier verschiedener Verschlusssysteme.

BACKGROUND AND OBJECTIVE: Surgical closure of secundum atrial septal defect (ASD) or patent foramen ovale (PFO) is a procedure with few complications. But this surgical intervention can nowadays be avoided by transcatheter insertion of occluding devices. Such interventional methods must be judged against the results of surgical procedures. This report from one center presents the practicability and safety of different transcatheter occluder systems. PATIENTS AND METHODS: Transcatheter occlusion was undertaken in 102 patients (40 females, 62 males, aged between 17 and 76 years [median age 45]) with either an ASD (41pts.) or a PFO (60 pts.) or with both, in one patient. Four different systems were used: ASDOS (for ASD and PFO), PFO-STAR (for PFO), Amplatzer Septal Occluder (for ASD) or Amplatzer PFO Occluder (for PFO). Follow-up, including transoesophageal echocardiography took place 48 hours, 4 weeks, 6 months and 1 year after the interventional occluder placement. RESULTS: An occluder was successfully placed in the ASD or PFO in 99 of the 102 patients. In three patients the occluder ( ASDOS ASD) could not be correctly ancchored in the defect. In two other patients the same device was subsequently removed surgically because of mispositioning or a large resiudal shunt. Occluder-associated problems were: mild (41%) or extensive (11%) thrombus formation on the occluder without early embolization, residual shunt at one year (ASD 16%, PFO 29%); minor displacement (10%) or broken umbrella strut (6%) of no clinical relevance. One patient required emergency surgical intervention on the day of the transcatheter placement (PFO-STAR) because of pricardial tamponade. Primary complete occlusion was achieved in 71%. There was no case of cerebral emboli. CONCLUSION: Transcatheter occlusion of ASD and/or PFO is a reliable and safe procedure. Regarding peri- and/or postinterventional complications, primary results and practicability, the Amplatzer septal occluder and Amplatzer PFO occluder are particularly advantageous.

Synthesis and pharmacology of site specific cocaine abuse treatment agents: a new synthetic methodology for methylphenidate analogs based on the Blaise reaction.

In order to make new analogs of the dopamine (DA) uptake inhibitor methylphenidate, a synthetic methodology based on the Blaise reaction was developed. The reaction between alpha-bromophenylacetic acid esters, zinc and alpha-cyano-omega-mesylates gave stable primary enamines. After reduction of the enamines with cyanoborohydride, the amines could be cyclized to methylphenidate analogs in which the amine ring size and aromatic ring were varied. These compounds were tested for inhibitory potency against [(3)H]WIN 35,428 binding to the cocaine recognition site and [(3)H]DA uptake using rat striatal tissue. When the heterocyclic ring size was varied, the six-membered ring of methylphenidate appeared to be the optimum ring size. When the aryl ring was varied the 4-trifluoromethylphenyl analog was less potent than methylphenidate, the beta-naphthyl congener was considerably more potent, whereas the alpha-naphthyl congener was less potent. Most of the compounds tested had ratios of uptake to binding inhibition (discrimination ratio) that were similar to cocaine and were therefore not lead compounds for the development of cocaine antagonists.

Adjunctive use of endoscopy during posterior fossa surgery to treat cranial neuropathies.

OBJECTIVE: The objective of this study was to determine the utility and safety of rigid endoscopy as an adjunct during posterior fossa surgery to treat cranial neuropathies. METHODS: A suboccipital craniotomy was performed for 19 patients with non-neoplastic processes involving the Vth, VIIth, and/or VIIIth cranial nerves. Ten patients with trigeminal neuralgia (n = 8), hemifacial spasm (n = 1), or intractable tinnitus (n = 1) underwent primarily microvascular decompression procedures. One patient with geniculate neuralgia underwent nervus intermedius sectioning combined with microvascular decompression. Eight patients underwent unilateral vestibular nerve neurectomies for treatment of Meniere's disease. A 0- or 30-degree rigid endoscope was used in conjunction with the standard microscopic approach for all procedures. RESULTS: All patients experienced resolution or significant improvement of their preoperative symptoms after posterior fossa surgery. The endoscope allowed improved definition of anatomic neurovascular relationships without the need for significant cerebellar or brainstem retraction. Cleavage planes between the cochlear and vestibular nerves entering the internal auditory canal and sites of vascular compression could not be microscopically observed for several patients; however, endoscopic identification was possible for all patients. There were no complications related to the use of the endoscope. CONCLUSION: The rigid endoscope can be used safely during posterior fossa surgery to treat cranial neuropathies, and it allows improved observation of the cranial nerves, nerve cleavage planes, and vascular anatomic features without significant cerebellar or brainstem retraction.

Infrasellar craniopharyngiomas: case report and review of the literature.

Although craniopharyngiomas account for a large percentage of pediatric intracranial tumors, there is a bimodal age distribution. Most of these neoplasms are suprasellar or sellar in location. In this report we describe an unusual case of an infrasellar craniopharyngioma in a child. Only four previous cases of infrasellar craniopharyngiomas with no sellar involvement have been described. Infrasellar craniopharyngiomas are part of the continuum representing intracranial craniopharyngiomas and ameloblastomas of the jaw. A transnasal endoscopic biopsy was performed with a preliminary diagnosis of craniopharyngioma. The patient then underwent a radical resection of the infrasellar tumor via a subfrontal transbasal approach. This case illustrates a rare and unusual location for a craniopharyngioma. Craniopharyngiomas should be considered in the differential diagnosis of infrasellar neoplasms. Infrasellar craniopharyngiomas compromise part of the spectrum of tumors originating from enamel-forming neural crest cells.

Identification of hemodynamically significant restenosis after percutaneous transluminal coronary angioplasty in acute myocardial infarction by transesophageal dobutamine stress echocardiography and comparison with myocardial single photon emission computed tomography.

BACKGROUND: Beside thrombolysis, percutaneous transluminal coronary angioplasty (PTCA) has become a well-established treatment for acute myocardial infarction. However, restenosis occurs in approximately 15%-40% of patients. Despite a frequently occurring infarct-related regional systolic dysfunction at rest, the identification of hemodynamically relevant restenosis seems important in terms of risk stratification, adequate treatment, and possible improvement of prognosis in these patients. This study was designed to assess the role of transesophageal dobutamine stress echocardiography and myocardial scintigraphy for identification of hemodynamically significant restenosis after PTCA for acute myocardial infarction. METHODS: Multiplane transesophageal stress echocardiography (dobutamine 5, 10, 20, 30, and 40 micrograms/kg per min) studies and myocardial single photon emission computed tomography (SPECT) studies were performed in 40 patients, all of whom underwent PTCA in the setting of acute myocardial infarction > or = 4 months prior to the test. Repeated coronary angiography was performed in all study patients who showed stress-induced perfusion defects or wall-motion abnormalities, or both. RESULTS: Significant restenosis (> or = 50%) was angiographically found in 15 (37.5%) of 40 patients. Of these 15 patients, transesophageal dobutamine stress echocardiography identified restenosis in 12 (80%) and myocardial SPECT in 14 (93%), yielding diagnostic agreement in 70% of patients. Echocardiographic detection of restenosis was based mainly on a biphasic response to increasing doses of dobutamine. Sensitivity and specificity for identification of hemodynamically relevant restenosis in individual patients was 80% and 92%, respectively for dobutamine stress echocardiography versus 93% and 68% for myocardial SPECT. CONCLUSIONS: Both transesophageal dobutamine stress echocardiography and myocardial SPECT were highly sensitive in identifying significant restenosis after PTCA for acute myocardial infarction. Therefore, either test, as a single diagnostic tool or especially if performed together, are clinically valuable alternatives to coronary angiography for the detection of restenosis after PTCA for acute myocardial infarction.

Endoscopic endocrine neck surgery with carbon dioxide insufflation: the effect on intracranial pressure in a large animal model.

BACKGROUND: Endoscopic endocrine neck surgery requires insufflation with carbon dioxide (CO(2)) at 10 to 15 mm Hg, which may decrease the cerebral venous return and increase intracranial pressure. This study evaluated the effect of CO(2) neck insufflation on intracranial pressure (ICP) and hemodynamic parameters. METHODS: Fifteen pigs underwent endoscopic thyroid dissection. Insufflation was performed with CO(2) at 0 (sham), 10, 15, and 20 mm Hg and with helium at 20 mm Hg with 3 pigs in each group. ICP, mean arterial pressure, central venous pressure (CVP), cardiac output, and blood gas were measured at baseline, 30, 60, and 120 minutes. RESULTS: There were no differences in mean ICP between the sham group and CO(2) insufflation at 10 mm Hg. Mean ICP increased significantly with CO(2) at 15 and 20 mm Hg and with helium at 20 mm Hg. A significant increase in CVP occurred in pigs operated with CO(2) at 20 mm Hg. We observed jugular vein collapse under all insufflation pressures; however, pigs operated at 10 mm Hg were able to maintain an intermittent blood flow. CONCLUSIONS: A severe increase in ICP occurs with insufflation pressures higher than 15 mm Hg, possibly as a result of decreased cervical venous blood flow. Carbon dioxide insufflation up to 10 mm Hg does not alter ICP and is recommended for clinical application in endoscopic neck surgery.

Long-term follow-up of 82 patients with chronic disease of the thoracic aorta using spin-echo and cine gradient magnetic resonance imaging.

The objective of this study to examine the clinical impact of magnetic resonance imaging in long-term follow-up of patients (pts) with chronic disease of the thoracic aorta such as coarctation of the aorta, chronic aortic dissection and true aortic aneurysm. A total of 322 magnetic resonance examinations obtained in 82 pts with chronic disease of the thoracic aorta (31 pts with coarctation of the aorta (CoA), 29 pts with chronic aortic dissection and 22 pts with true aneurysm) over a period of 0.25 to 13.5 (mean +/- SD: 6.5 +/- 3.4) years were retrospectively reviewed. Diameters of the thoracic aorta were measured at predefined levels and morphological and functional parameters of special interest were analysed in each patient group. Pts were classified as having constant or progressive disease and clinical end-points were defined as (re-)operation or death. 43 pts (52%) (CoA 15 pts, chronic dissection 16 pts, true aneurysm 12 pts) had constant findings. None of them underwent (re-)operation and seven patients (16%) died, three of them from their aortic disease more than five years later after their last magnetic resonance examination, one from an arrhythmogenic event, and in the remaining 3 pts the cause of death could not be definitely established. 39 pts (48%) (CoA 16 pts, chronic dissection 13 pts, true aneurysm 10 pts) had progressive disease as demonstrated by repetitive magnetic resonance imaging. Of these 39 pts 24 pts underwent (re-)operation, in 15 pts operation was postponed. Four pts died from their aortic disease. Repetitive magnetic resonance imaging is a clinically feasible technique for long-term follow-up of pts with chronic disease of the thoracic aorta because it can detect progressive disease in a large subset of pts requiring elective surgery. The results of magnetic resonance imaging provided the rationale for either (re-)operation or conservative management, thus guiding patient management.

Isolation and properties of human alpha-fetoprotein from HepG2 cell cultures.

A relatively rapid 3-step fractionation method has been developed for the isolation of human alpha-fetoprotein from culture fluids of HepG2 cells applicable to large volumes. The protein exists as a complex with lipids or lipoproteins but an ethanol precipitation step is effective in separating it. Yields of 50-60% can be obtained from culture fluid containing 30-40 microg/ml. A minor fraction that appears to be a proteolytic product of the AFP is present in the final product.

Head to head comparison of dobutamine-transoesophageal echocardiography and dobutamine-magnetic resonance imaging for the prediction of left ventricular functional recovery in patients with chronic coronary artery disease.

AIMS: A substantial number of patients with dysfunctional but potentially viable myocardium cannot be accurately evaluated by transthoracic echocardiography due to a poor acoustic window. This study compares the diagnostic value of alternative functional imaging techniques, such as dobutamine-transoesophageal echocardiography (dobutamine-TEE) and dobutamine magnetic resonance imaging (dobutamine-MRI) for the detection of viable myocardium and the prediction of left ventricular functional recovery in patients with chronic coronary artery disease following successful revascularization procedures. METHODS AND RESULTS: Rest and low-dose (5, 10 microg dobutamine x min(-1) x kg(-1)) multiplane dobutamine-TEE and ultrafast cine-MRI studies were performed in 103 patients. Contractile recovery of an infarct region was predicted if a dobutamine contraction reserve could be assessed visually by TEE or MRI in > or =50% of infarct-related a- or dyskinetic segments. Revascularization of the infarct-related vessel was successful in 88 patients, and 4.9 +/- 0.7 months later 52 patients still had an angiographically controlled open target vessel. These patients underwent another rest MRI study to assess left ventricular functional recovery. A dobutamine contraction reserve was observed in 27/52 (52%) patients by TEE and in 26/52 (50%) patients by MRI. Functional improvement of the infarct region was diagnosed in 28/52 (54%) patients. The positive and negative predictive accuracy of dobutamine-TEE and dobutamine-MRI for the prediction of left ventricular functional recovery was not significantly different (85% vs 92%, ns and 80% vs 85%, ns). Diagnosis of a predominantly viable infarct region by TEE and MRI predicted a significant increase in left ventricular ejection fraction (TEE: 12 +/- 8% vs 2 +/- 7% P<0.001, MRI: 13 +/- 7% vs 2 +/- 7%, P<0.001) compared to infarct regions graded as scar. CONCLUSION: A qualitative visual analysis of TEE and MRI viability studies is highly accurate for the prediction of left ventricular functional recovery in patients with dysfunctional myocardium and proved to be a clinically valuable alternative if transthoracic dobutamine-echocardiography is unsuitable. To date, TEE is cardiologists' preferred choice for the assessment of myocardial viability but MRI may become significantly more attractive with increasing local availability and experience.