Double lumen endobronchial tube intubation: lessons learned from anatomy.

BACKGROUND: Double lumen endobronchial tubes (DLTs) are frequently used to employ single lung ventilation strategies during thoracic surgical procedures. Placement of these tubes can be challenging even for experienced clinicians. We hypothesized that airway anatomy, particularly of the glottis and proximal trachea, significantly impacts the ease or difficulty in placement of these tubes. METHODS: Images from 24 randomly selected Positron Emission Tomography - Computed Tomography (PET-CT) scans were evaluated for several anatomic aspects of the upper airway, including size and angulation of the glottis and proximal tracheal using calibrated CT measurements and an online digital protractor. The anatomic issues identified were confirmed in cadaveric anatomic models. RESULTS: Proximal tracheal diameter measurements in PET-CT scans demonstrated a mean ± standard deviation of 20.4 ± 2.5 mm in 12 males and 15.5 ± 0.98 mm in 12 females (p < 0.001), and both were large enough to accommodate 39 French and 37 French DLTs in males and females, respectively. Subsequent measurements of the posterior angulation of the proximal trachea revealed a mean angle of 40.8 ± 5.7 degrees with no sex differences. By combining the 24 individual posterior tracheal angles with the 16 angled distal tip measurements DLTs (mean angle 24.9 ± 2.1 degrees), we created a series of 384 patient intubation angle scenarios. This data clearly showed that DLT rotation to a full 180 degrees decreased the mean intubation angle between the DLT and the proximal trachea from a mean of 66.6 ± 5.9 to only 15.8 ± 5.9 degrees. CONCLUSIONS: Rotation of DLTs a full 180 instead of the recommended 90 degrees facilitates DLT intubations.

Sympathetic innervation of the supraclavicular brown adipose tissue: A detailed anatomical study.

BACKGROUND: The supraclavicular fossa is the dominant location for human brown adipose tissue (BAT). Activation of BAT promotes non-shivering thermogenesis by utilization of glucose and free fatty acids and has been the focus of pharmacological and non-pharmacological approaches for modulation in order to improve body weight and glucose homeostasis. Sympathetic neural control of supraclavicular BAT has received much attention, but its innervation has not been extensively investigated in humans. METHODS: Dissection of the cervical region in human cadavers was performed to find the distribution of sympathetic nerve branches to supraclavicular fat pad. Furthermore, proximal segments of the 4th cervical nerve were evaluated histologically to assess its sympathetic components. RESULTS: Nerve branches terminating in supraclavicular fat pad were identified in all dissections, including those from the 3rd and 4th cervical nerves and from the cervical sympathetic plexus. Histology of the proximal segments of the 4th cervical nerves confirmed tyrosine hydroxylase positive thin nerve fibers in all fascicles with either a scattered or clustered distribution pattern. The scattered pattern was more predominant than the clustered pattern (80% vs. 20%) across cadavers. These sympathetic nerve fibers occupied only 2.48% of the nerve cross sectional area on average. CONCLUSIONS: Human sympathetic nerves use multiple pathways to innervate the supraclavicular fat pad. The present finding serves as a framework for future clinical approaches to activate human BAT in the supraclavicular region.

Endoscope-Assisted Pedicled Maxillary Artery to Middle Cerebral Artery Bypass: An Anatomic Feasibility Study.

BACKGROUND: Extracranial to intracranial bypass is used to augment and/or replace the intracranial circulation for various pathologies. The superficial temporal artery is the mainstay donor for pedicled bypasses to the anterior circulation but can be limited by its variable size, low native flow rates, and potential scalp complications. Interposition grafts such as the radial artery or greater saphenous vein are alternatives but are sometimes limited by size mismatch, length needed to reach the extracranial circulation, and loss of inherent vascular elasticity. Interposition grafts between the maxillary artery (IMA) and middle cerebral artery (MCA) address these limitations. OBJECTIVE: To explore the feasibility of harvesting the IMA through an endoscopic transnasal, transmaxillary approach to perform a direct IMA to MCA bypass. METHODS: Combined transcranial and endoscopic endonasal dissections were performed in embalmed human cadavers to harvest the IMAs for intracranial transposition and direct anastomosis to the MCA. Donor and recipient vessel calibers were measured and recorded. RESULTS: A total of 8 procedures were performed using the largest and distal-most branches of the IMA (the sphenopalatine branch and the descending palatine branch) as pedicled conduits to second division of middle cerebral artery (M2) recipients. The mean diameter of the IMA donors was 1.89 mm (SD ± 0.42 mm), and the mean diameter of the recipient M2 vessels was 1.90 mm (SD ± 0.46 mm). CONCLUSION: Endoscopic harvest of the IMA using a transnasal, transmaxillary approach is a technically feasible option offering an excellent size match to the M2 divisions of the MCA and the advantages of a relatively short, pedicled donor vessel.

Living Anatomy of the Pericardial Space: A Guide for Imaging and Interventions.

The pericardium of the human heart has received increased attention in recent times due to interest in the epicardial approach for cardiac interventions to treat cardiac arrhythmias refractory to conventional endocardial approaches. To support further clinical application of this technique, it is fundamental to appreciate the living anatomy of the pericardial space, as well as its relationships to the surrounding structures. The anatomy of the pericardial space, however, is extremely difficult regions to visualize. This is due to its complex 3-dimensionality, and the "potential" nature of the space, which becomes obvious only when there is collection of pericardial fluid. This potential space, which is bounded by the epicardium and pericardium, can now be visualized by special techniques as we now report, permitting appreciation of its living morphology. Current sources of knowledge are limited to the dissection images, surgical images, and/or illustrations, which are not necessarily precise or sufficient to provide relevant comprehensive anatomical knowledge to those undertaking the epicardial approach. The authors demonstrate, for the first time to their knowledge, the 3-dimensional living anatomy of the pericardial space relative to its surrounding structures. They also provide correlative anatomy of the left sternocostal triangle as a common site for subxiphoid access. The authors anticipate their report serving as a tool for education of imaging and interventional specialists.

Mixed-Method Evaluation of a Cadaver Dissection Course for General Surgery Interns: An Innovative Approach for Filling the Gap Between Gross Anatomy and the Operating Room.

OBJECTIVE: To evaluate an innovative whole cadaver dissection curriculum designed to focus on teaching procedure-relevant anatomy and surgical skills to surgery interns. DESIGN: A mixed methods explanatory sequential design incorporating both quantitative and qualitative evaluations was used to evaluate the cadaver dissection course. Quantitative data were prospectively collected and retrospectively reviewed in order to compare anatomy knowledge and operative skills before and after the course. In the qualitative phase, open-ended telephone interviews were conducted in order to explore the major strengths and weaknesses of the course and gain a more in-depth understanding of resident perceptions and attitudes toward the course. SETTING: All UCLA categorical surgery interns who have undergone the cadaver dissection curriculum between the years 2010 to 2016 were recruited for evaluation and interview. PARTICIPANTS: From 2010 to 2016, 6 to 7 categorical surgery interns were enrolled in the cadaver dissection course each year. RESULTS: Anatomy practical examination scores increased following implementation of the course from 50.5% to 83.5% (p < 0.01). Faculty ratings of operative skills improved as well (average Likert scale rating for technical skills improved from 4.1 ± 0.4 to 4.4 ± 0.3, p = 0.06). Almost all interviewees (96%) reported that the course improved their knowledge of anatomy, and 78% of respondents believed the course was conducive to improving technical skills. CONCLUSIONS: We believe that cadaver dissection courses offer a superior educational model for teaching clinically relevant anatomy as well as surgical skills. We found improvements in anatomy knowledge and technical skills, and trainees expressed strongly favorable views of the program.

A novel cadaver-based educational program in general surgery training.

OBJECTIVE: To describe the development of a cadaver-based educational program and report our residents' assessment of the new program. DESIGN: An anatomy-based educational program was developed using fresh frozen cadavers to teach surgical anatomy and operative skills to general surgery (GS) trainees. Residents were asked to complete a voluntary, anonymous survey evaluating perceptions of the program (6 questions formulated on a 5-point Likert scale) and comparing cadaver sessions to other types of learning (4 rank order questions). SETTING: Large university teaching hospital. PARTICIPANTS: Medical students, residents, and faculty members were participants in the cadaver programs. Only GS residents were asked to complete the survey. RESULTS: Since its implementation, 150 residents of all levels participated in 13 sessions. A total of 40 surveys were returned for a response rate of 89%. Overall, respondents held a positive view of the cadaver sessions and believed them to be useful for learning anatomy (94% agree or strongly agree), learning the steps of an operation (76% agree or strongly agree), and increasing confidence in doing an operation (53% agree or strongly agree). Trainees wanted to have more sessions (87% agree or strongly agree), and believed they would spend free time in the cadaver laboratory (58% agree or strongly agree). Compared with other learning modalities, cadaver sessions were ranked first for learning surgical anatomy, followed by textbooks, simulators, web sites, animate laboratories, and lectures. Respondents also ranked cadaver sessions first for increasing confidence in performing a procedure and for learning the steps of an operation. Cost of cadavers represented the major expense of the program. CONCLUSIONS: Fresh cadaver dissections represent a solution to the challenges of efficient, safe, and effective general surgery education. Residents have a positive attitude toward these teaching sessions and found them to be more effective than other learning modalities.

Functional status of patients with cerebral palsy according to the International Classification of Functioning, Disability and Health model: a 20-year follow-up study after selective dorsal rhizotomy.

OBJECTIVE: To determine functional status of patients with cerebral palsy 20 years after they received selective dorsal rhizotomy (SDR). DESIGN: A prospective 20-year follow-up study. SETTING: Red Cross Children's Hospital (SDR operation and 1-year follow-up assessment) and at institutional or private locations nearby patients' homes (20-year follow-up assessment). PARTICIPANTS: Referred sample of 14 patients with spastic diplegia (6 women, 8 men; mean age, 27y; range, 22-33y) who were preoperatively ambulant and fulfilled strict selection criteria for SDR operation in 1985. INTERVENTIONS: Patients were assessed before and 1 and 20 years after SDR. MAIN OUTCOME MEASURES: Standardized assessments of function according to 2 dimensions of the International Classification of Functioning, Disability and Health (ICF) model: (1) body structure and function (muscle tone, joint stiffness, voluntary movement) and (2) activity (rolling, sitting, kneeling, crawling, standing, walking, transitions) were obtained. In addition, based on assessments and questionnaires, Gross Motor Function Classification System (GMFCS) levels were determined before and at 1 year after SDR retrospectively and currently at 20 years after SDR. RESULTS: One year after SDR, functional outcomes based on the 2 dimensions of the ICF model improved significantly, and these improvements were maintained at 20 years after surgery. Patients showed a shift in their GMFCS levels 1 and 20 years after SDR. CONCLUSIONS: In line with our 20-year follow-up study with gait parameters as outcome measures, patients with spastic diplegia still show improvements in their functional status 20 years after SDR. We acknowledge the presence of possible confounding factors and a small sample size, but we argue that the improvements found in this study were caused mainly by SDR. Finally, changes in GMFCS levels suggest a possible role for this tool to detect changes after an intervention.

A prospective gait analysis study in patients with diplegic cerebral palsy 20 years after selective dorsal rhizotomy.

OBJECTIVES: Selective dorsal rhizotomy (SDR) has been widely performed for the reduction of spasticity in patients with cerebral palsy during the past 2 decades. The objective of this study was to determine whether the surgery has yielded long-term functional benefits for these patients. METHODS: The authors present results from a prospective 20-year follow-up study of locomotor function in 13 patients who underwent an SDR in 1985. For comparison, we also present gait data for 48 age-matched healthy controls (12 at each of 4 time points). Patients were studied preoperatively and then at 1, 3, 10, and 20 years after surgery. Study participants were recorded in the sagittal plane while walking using a digital video camera, and 6 standard gait parameters were measured. RESULTS: In this group of patients 20 years after surgery, knee range of motion (ROM) was on average 12 degrees greater than preoperative values (p < 0.001). Hip ROM before surgery was no different from that in the healthy control group. This parameter increased markedly immediately after surgery (p < 0.001) but had returned to normal after 20 years. The knee and hip midrange values-a measure of the degree of "collapse" due to muscle weakness after surgery-had returned to preoperative levels after 20 years, although they were respectively 11 and 8 degrees greater than those in healthy controls. Both temporal-distance parameters (dimensionless cadence and dimensionless step length) were significantly greater at 20 years than preoperative values (cadence, p = 0.003; step length, p = 0.02), leading to improved walking speed. CONCLUSIONS: Twenty years after undergoing SDR, our patients showed improved locomotor function compared with their preoperative status.

Selective dorsal rhizotomy: long-term experience from Cape Town.

INTRODUCTION: Given the large number of cerebral palsy patients who have undergone selective dorsal rhizotomy in the past two decades, it is clearly imperative that the clinical community be provided with objective and compelling evidence of the long-term sequelae of the procedure. MATERIALS AND METHODS: In the early 1980s, Peacock in Cape Town shifted the site of the rhizotomy from the conus medullaris to the cauda equina, and in the past 25 years, more than 200 children have been operated on. We have studied the incidence of spinal deformities after multiple-level laminectomy and recorded a 20% incidence of isthmic spondylolysis or grade-I spondylolisthesis. We have also conducted a long-term prospective gait analysis study on a cohort of 14 ambulatory patients who were operated on in 1985. RESULTS: Ten years after surgery, our patients had increased ranges of motion that were within normal limits. Step length was significantly improved, although cadence was unchanged postoperatively and was significantly less than normal age-matched control subjects. DISCUSSION: We have recently tracked down all 14 patients from the original cohort and are currently completing a 20-year prospective follow-up analysis of their neuromuscular function and gait. Our preliminary data suggest that selective dorsal rhizotomy is not only an effective method for alleviating spasticity but it also leads to long-term functional benefits.

In utero repair of myelomeningocele: experimental pathophysiology, initial clinical experience, and outcomes.

HYPOTHESIS: Experimental work raises the possibility that in utero repair of myelomeningocele (MMC) may improve lower extremity, bladder, and bowel function, ameliorate the Arnold-Chiari malformation, and decrease the need for postnatal shunting. DESIGN: We previously developed fetal lamb models to create and reverse lower extremity damage and the Arnold-Chiari malformation in utero. We then applied our extensive experience with fetal surgery, including fetal endoscopic (fetoscopic) surgical manipulation, to develop techniques for MMC repair. SETTING: A tertiary referral center. PATIENTS: All patients treated between 1998 and 2002 for a prenatally diagnosed MMC. INTERVENTIONS: Either fetoscopic MMC repair, fetoscopic patch repair, or limited maternal hysterotomy and microsurgical 3-layered fetal MMC repair was performed. MAIN OUTCOME MEASURES: Gestational age at delivery, survival, neurologic outcome, and need for ventricular shunting at 1 year. RESULTS: Complete fetoscopic repair was accomplished in 1 fetus. Two other fetuses underwent partial fetoscopic procedures. The remaining 10 patients underwent limited maternal hysterotomy and microsurgical 3-layered fetal MMC repair. Four of 13 patients died, and the mean gestational age at delivery of 11 fetuses born alive was 31 weeks. Five of 9 required ventricular shunting by age 1 year. In 2 patients, lower extremity function improved by more than 2 vertebral levels compared with prenatal ultrasonography. Five of 10 patients who lived longer than 3 weeks required postnatal wound revision within 7 days after birth. CONCLUSIONS: Fetoscopic repair, although feasible, does not yet yield optimal surgical results. Open surgical repair before 22 weeks' gestation is physiologically sound and technically feasible. One third of patients appear to be spared the need for a shunt at age 1 year, but improvement in distal neurologic function is less clear. Additionally, fetal mortality is associated with this procedure. Our results complement the data published by groups at Children's Hospital of Philadelphia, in Pennsylvania, and Vanderbilt University, Nashville, Tenn. A National Institutes of Health-sponsored prospective randomized trial is now underway at these 3 centers to compare fetal repair with postnatal repair.

Clinical outcome in children undergoing tethered cord release utilizing intraoperative neurophysiological monitoring.

Release of tethered spinal cord by sectioning of the filum terminale carries a risk of injuring neighboring motor and sensory nerve roots involved in bowel and bladder control. Therefore, intraoperative neurophysiological monitoring techniques have been developed to prevent neurological complications postoperatively. We performed a retrospective chart review of 63 patients who had undergone tethered cord release. We excluded adult patients, those lost to follow-up and patients with either a myelomeningocele and/or lipoma. This limited our study to 25 pediatric patients, aged 4 months to 12 years, who underwent tethered cord release for either a thickened filum terminale and/or a low-lying conus. For intraoperative monitoring, we utilized electrical stimulation of the filum terminale, lumbosacral nerve roots and electromyography recordings. Ventral nerve roots were identified and their electrical thresholds obtained. The mean was 0.32 V, the mode 0.1 V and the range 0.05-1.0 V. These values were compared to electrical thresholds obtained by stimulation of the filum terminale. The mean was 26.1 V, the mode 20.0 V and the range 8-100 V. In over 70% of patients, muscle activation via the filum required 100 times the voltage needed to activate a motor root. This motor root to filum threshold of 1:100 was useful in identifying the filum. Clinical outcome showed no significant worsening with respect to bowel and bladder control or pain and motor indices. Significant bowel and bladder improvement was seen in 4 out of 25 patients, motor improvement in 9 out of 25 patients and improvement of pain in 4 out of 25 patients. Three patients developed postoperative urinary tract infections, but no cerebrospinal fluid leaks or pseudomeningoceles were encountered. These results suggest that patients with a thickened filum or low-lying conus can safely undergo tethered cord release. Intraoperative neurophysiological monitoring provides a helpful adjunct to distinguish nerve roots from the filum. A ratio, rather than an absolute number, is beneficial in distinguishing motor roots from the filum and eliminates variability due to patients' individual differences in electrical thresholds.