Surgical anatomy of the temporal bone: an atlas.

This atlas demonstrates the usefulness of reconstructed high-resolution CT for planning temporal bone surgery. The first part focuses on a sagittal plane, the second on a rotated longitudinal plane, and the third on a rotated transverse plane. We believe knowledge of temporal bone anatomy in these planes facilitates surgical planning by showing anatomic relationships and providing a customized map for each patient. This decreases the likelihood of surgical mishap and improves teaching.

Sectional imaging anatomy: pelvic ring ligaments.

The purpose of this article is to describe the complex anatomy of the pelvic ligaments. It uses schematics to display 10 color-coded ligaments in relation to the bony architecture. This atlas and the accompanying summary of the classification of pelvic ligamentous injuries is designed to encourage the use of magnetic resonance imaging in cases of pelvic ring trauma.

Sectional neuroanatomy of the lower limb II: leg and foot.

The authors have produced a pair of articles that can be used to rapidly identify back, hip, and lower limb muscles and their innervation(s). This article presents the motor and sensory innervation of the lower limb by color-coding structures to match their peripheral nerves. It provides a companion summary table that allows prediction of unique patterns of denervation from 12 lesions sites.

Sectional neuroanatomy of the lower limb I: lower back and hip.

This series of two articles is structured to provide anatomically accurate functional schematics of the motor and sensory innervation of the lower back, hip, and lower limb. This first paper provides radiographically oriented schematic axial sections of the lower back and hip in which the muscles are appropriately color-coded to match the peripheral nerves. A companion color-coded summary table allows prediction of unique patterns of denervation from 25 lesion sites. These are divided into three categories (roots T12 to S4, four plexal quadrants, and 11 sectional levels). Correlation between an imaging abnormality at one of these lesion sites and the predicted denervation pattern ensures the lesion is, in fact, clinically significant. The next article will continue this color-coded approach into the lower limb.

Cost-effectiveness of universal cystoscopy to identify ureteral injury at hysterectomy.

OBJECTIVE: To evaluate the cost-effectiveness of routine cystoscopy at the time of abdominal, vaginal, and laparoscopically assisted vaginal hysterectomy in terms of cost per ureteral injury identified and treated. METHODS: Using a hospital-based perspective, a decision-analysis model was constructed to estimate the outcomes and costs of cystoscopy or no cystoscopy at the time of abdominal hysterectomy. A similar model was constructed for vaginal and laparoscopically assisted vaginal hysterectomy to account for the cost of conversion to laparotomy. Cost estimates were based on estimated costs of Duke University Medical Center and from average Medicare reimbursements for similar Diagnostic Related Groups from the Health Care Financing Administration. The incidence of ureteral injury was obtained from a review of the literature. Sensitivity analyses were performed for the following variables: ureteral injury rate, silent ureteral injury rate, cost of cystoscopy, and cost of therapeutic interventions. We assumed a silent renal death rate of 0%. RESULTS: Routine cystoscopy at abdominal hysterectomy was cost-saving above a threshold ureteral injury rate of 1.5%. At a ureteral injury rate of 0.2%, the marginal increase in the cost of routine intraoperative cystoscopy was $108 per abdominal hysterectomy, with an associated cost of $54,000 per ureteral injury identified. In comparison, at a ureteral injury rate of 2%, routine cystoscopy gave a marginal cost savings of $44 per hysterectomy, with a cost savings of $2200 per ureteral injury identified intraoperatively. At the baseline ureteral injury rate of 0.5%, routine cystoscopy had a marginally increased cost of $83 per hysterectomy, with an incremental cost-effectiveness of $16,600 spent per ureteral injury identified. The model constructed for vaginal hysterectomy and laparoscopically assisted vaginal hysterectomy yielded a threshold ureteral injury rate of 2%, above which routine cystoscopy was cost-saving. In both models, the incidence of ureteral injury and the cost of readmission were the two variables with the greatest influence on cost-effectiveness. CONCLUSION: The cost-effectiveness of routine intraoperative cystoscopy depends on the rate of ureteral injury independent of the route of hysterectomy. If that rate exceeds 1.5% for abdominal hysterectomy and 2% for vaginal or laparoscopically assisted vaginal hysterectomy, then routine cystoscopy is cost-effective.

Reconciliation of the anatomic, surgical, and radiographic classifications of the mediastinum.

The mediastinum is a complex region that is variously subdivided by radiologists, surgeons and anatomists. This paper describes the most popular of these classifications and color-codes the radiologic and surgical divisions on 22 labeled axial sections of the chest. This allows the reader to quickly name the appropriate location of a lesion on any section.

Sectional neuroanatomy of the upper limb III: forearm and hand.

This paper is the last of three articles that describe the functional anatomy of the upper limb. It extends the series by presenting the axial anatomy of the forearm and hand. In addition, it provides a table that defines the patterns of muscle denervation specific to six representative sites. This set of articles is clinically useful because it can be used to rapidly identify and describe the innervation of the muscles and skin of the upper limb.

Sectional neuroanatomy of the upper limb II: shoulder and upper arm.

This article is the second in a series of three that presents an anatomic functional guide to the peripheral innervation of the shoulder and upper limb. It illustrates the axial anatomy of the shoulder and upper arm. The next article continues this format for the lower arm and hand. Together, all three papers can be used to rapidly identify each upper limb muscle and its innervation(s). They can also be used to locate the peripheral nerve trunks, and correlate lesions with the classic pattern(s) of muscle denervation and altered sensation.

Use of reconstructed sagittal computed tomography images to plan middle cranial fossa surgery.

OBJECTIVE: To facilitate planning in temporal bone surgery for the middle cranial fossa approach by using sagittal reconstructed temporal bone computed tomography images. STUDY DESIGN: Comparison of anatomic measurements on random high-resolution, reformatted computed tomography scans of the temporal bone. METHODS: High-resolution computed tomography of 10 normal temporal bones in the axial and coronal planes was obtained, and two-dimensional sagittal reconstructions were performed using a commercial software program. Eight anatomical relationships between neural and/or vascular structures were measured. Representative images were inverted to recreate the plane of the middle cranial fossa approach. RESULTS: Anatomical relationships among the vestibule, superior semicircular canal, internal auditory canal, internal carotid artery, and middle cranial fossa exhibited a high SD in the 10 subjects. The sample size and the large range for the eight anatomical relationships precluded the detection of a significant difference between right and left temporal bones or sex and age of the patient. CONCLUSION: The present report presents a novel, practical measurement protocol for rapidly evaluating important individual anatomical differences in patients before middle cranial fossa surgery. Inverted sagittal reconstructions facilitate presurgical planning for the middle cranial fossa approach by 1) assessing critical anatomical relationships before surgery and 2) providing customized measurements between vital landmarks and the first in vivo measurements. This decreases the likelihood of surgical mishaps and improves teaching by providing the first in vivo measurements of practical anatomical relationships in the sagittal plane.

Sectional neuroanatomy of the upper limb I: brachial plexus.

This series of three articles is structured to provide anatomically accurate functional schematics of the motor and sensory innervation of the shoulder and upper limb. This first paper provides radiographically oriented sagittal sections through the brachial plexus to assist in directly identifying a plexal lesion. A coronal schematic of the brachial plexus and summary table allows prediction of unique patterns of denervation from 19 lesion sites. Correlation between the lesion and the denervation pattern ensures the lesion is, in fact, clinically significant. The next two articles will present a color-coded atlas that allows the radiologist to quickly assess patterns of denervated muscles and thereby indirectly localize the lesion site. Thus, the three articles can be used together to predict the clinical picture for a given nerve lesion or extrapolate lesion location when a constellation of denervated muscles are seen on an upper limb magnetic resonance imaging or electromyographic study.

The nomenclature and sectional imaging anatomy III: capsular membranes and minor spinal ligaments.

This paper is the third in a series of three that organizes the complex anatomy of the cervical, thoracic, and lumbar spinal ligaments. It describes and color-codes the anatomy and nomenclature of the capsular membranes and minor spinal ligaments. The first two articles describe the dorsal and ventral ligaments, respectively.

In vivo measurements of temporal bone on reconstructed clinical high-resolution computed tomography scans.

PURPOSE: To retrospectively assess the accuracy of measurements of temporal bone anatomy made from reconstructed clinical high-resolution computed tomography (HRCT) scans. METHODS: Nine HRCT scans were performed on unselected clinical cases in which the subjects had a temporal bone study judged to be normal. The orbitomeatal line was prescribed for the direct axial sections. Variations in head position (rotation at the neck and lateral bending of the neck) were corrected by using the software supplied by the manufacturer. All measurements were done on standard 1-mm axial sections and axial reconstructions obtained from 1-mm coronal slices. The images were viewed at 4000 Hounsfield units (HU) window width and 1000 HU window level. Measurements (n = 3) made on 1-mm direct axial HRCT scans were compared with the measurements made on reconstructed axial HRCT images from the same nine patients. These values were also compared with published cadaver data. RESULTS: The measurements obtained from axial reconstructed and direct HRCT series approximated each other in each of the nine individual studies and also fell within the range of published cadaver values. They demonstrated the expected normal temporal bone variability between individuals. CONCLUSION: Useful anatomic approximations can be measured in vivo from reconstructed clinical HRCT images. Pitfalls are improper window settings, head tilt, and rotation. This protocol is widely available and can be implemented retrospectively from clinical HRCT scans.

The nomenclature and sectional imaging anatomy II: ventral spinal ligaments.

This paper is the second in a series of three that organizes the complex anatomy of the cervical, thoracic, and lumbar spinal ligaments. It describes and colorcodes the anatomy and nomenclature of the ventral ligaments. A prior article has described the dorsal ligaments, and a future article will illustrate the capsular joints and minor spinal ligaments.