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The negative autopsy: sudden cardiac death or other?

One of the most frustrating challenges faced by the forensic pathologist is the inability to determine the cause of death in a young person previously thought healthy. The four steps in the investigation of a sudden death include obtaining the history and scene information, performing a gross and microscopic autopsy, performing appropriate laboratory tests, and making the diagnosis. When examining the heart grossly it is important to preserve the anatomic landmarks, section the coronary arteries closely, and recognize lethal abnormalities such as anomalous origin of the coronary arteries. Specimens useful for toxicologic analysis include whole blood, serum, vitreous humor, gastric contents, bile, urine a purple top tube of blood, and frozen myocardium and spleen. Lethal cardiac diseases with minimal or no anatomic findings include Brugada and Garg's syndromes, the long QT syndrome, and Wolff-Parkinson-White (WPW) syndrome. Consultation with other experts, including cardiac pathologists, cardiologists, electrophysiologists, and molecular biologists, may be helpful in determining a cause of death.

Autopsy↗

Conservative management of large avulsions of the lip and local landmarks.

Large lip avulsion injuries that involve significant tissue loss to the lip vermilion and other local landmarks can often pose a surgical dilemma for the reconstructive surgeon. Immediate reconstruction of these injuries are frequently performed using local flaps and adjacent tissue transfer to close the defect, but these repairs frequently suffer from the unfortunate consequence of increased associated scarring and further permanent distortion of the local anatomy. We present 2 patients sustaining dog bite injuries associated with extensive traumatic tissue loss to the lip vermilion and other local landmarks. These patients were treated conservatively with excellent functional and cosmetic results. A single minor surgical revision of 1 patient's cupid's bow was performed 1 year after injury. In cases of significant traumatic avulsion involving the lip vermilion and the perioral composite soft tissue, even with injuries including delicate anatomic landmarks, healing by secondary intention can be instituted as the initial treatment of choice in younger patients, often providing optimal results.

Administration, Topical↗

Magnetic resonance imaging--a method of studying the size and asymmetry of the planum temporale.

The planum temporale is a triangular region on the upper surface of the temporal lobe. This area of the brain is important for language processing and shows a left-right asymmetry of size in most brains. Particular interest has been focused on the size and asymmetry of the planum temporale in brains of individuals with developmental dyslexia. Magnetic resonance imaging (MRI) is a method that produces excellent morphological details of organic structures. We have developed an MRI method of studying the size and asymmetry of the planum temporale in human brains. Because of considerable variation of anatomical landmarks in this cortical region of the brain, an evaluation of asymmetry is not possible in all brains. Furthermore, our experience with this method indicates that any indirect imaging technique of studying asymmetry of the planum temporale must be evaluated with caution. With this in mind, however, MRI may give valuable anatomical information about the planum temporale in individuals with anomalous language function.

Humans↗

[Internal mammary lymph nodes identification from isolated sternum of human cadaver].

PURPOSE: To identify the lymph nodes positioned along the internal mammary vessels in isolated sternum of human cadaver and to standardize the surgical approach to those nodes, in order to establish anatomical landmarks to be used with the current techniques of mammary gland sentinel lymph node detection. METHODS: Ten sternum plates removed from unclaimed cadavers were used in this study. Sternal plates were removed using bilateral incisions of the ribs at the midclavicular lines. The characterization of the internal mammary vessels and the anatomical integrity of the parietal pleura were indispensable requirements during the procedure. RESULTS: A total of 29 lymph nodes were removed from the 2nd (13) and the 3rd (16) intercostals spaces. Almost 50% of all nodes collected were located medially to the vessels. CONCLUSION: The approach used is a reliable surgical technique for removing lymph node from sternal plates. The model is therefore valuable for breast surgeons training in sentinel node biopsy, an important procedure for breast cancer patients.

Cadaver↗

Assessment of the knowledge of graduating American dental students about the panoramic image.

The objective of this study was to assess the capability of graduating dental students to identify the causes of undiagnostic panoramic images and to interpret anatomic landmarks on panoramic films. Seventeen dental schools were represented by 311 students. A radiology faculty member at each institution completed a questionnaire that addressed lecture time and experience provided to students in panoramic radiography. The faculty member administered a test instrument comprised of several panoramic radiographs that demonstrated one or more labeled anatomic structures, technical errors, or projection artifacts and multiple choice questions that addressed each entity. The mean percentage correct for the tested population on the entire test instrument was 72.9%. The mean percentage correct for questions addressing anatomy, error and artifact recognition, and error correction was 84.0%, 61.4% and 45.2%, respectively. Factors that significantly (p < 0.05) affected student performance were the number of lecture hours provided, whether or not students took panoramic radiographs of patients, and the method of student selection as participants. Laboratory or self-study projects and the number of panoramic radiographs (> or = 1) taken of patients did not significantly affect student performance on the test instrument.

Analysis of Variance↗

Craniofacial measurements based on 3D-CT volume rendering: implications for clinical applications.

OBJECTIVES: This study was designed to determine the precision and accuracy of anthropometric measurements using three-dimensional computed tomography (3D-CT) volume rendering by computer systems for craniofacial clinical applications, and to compare the craniometric landmarks using bone and soft tissue protocols. METHODS: The study population consisted of 13 cadaver heads that were examined with spiral CT. The archived CT data were transferred to a workstation, and 3D-CT volume rendered images were generated using computer graphics tools. Linear measurements (n = 10), based upon conventional craniometric anatomical landmarks (n = 08), were identified in 2D-CT and in 3D-CT images by two radiologists twice each independently, and then performed by 3D-CT imaging using a computer graphics systems using bone and soft tissue protocols. In total, 520 imaging measurements were made. The soft tissues were subsequently removed from the cadaver heads and the measurements were repeated using an electromagnetic 3 Space trade mark digitizer. RESULTS: The results demonstrated no statistically significant difference between interobserver and intraobserver measurements or between imaging and physical measurements in both 3D-CT protocols. The standard error was found to be between 0.45% and 1.44% for all the measurements in both protocols, indicating a high level of precision. Furthermore, there was no statistically significant difference between imaging and physical measurements (P > 0.01). The error between the mean actual and mean 3D-based linear measurements was 0.83% for bone and 1.78% for soft tissue measurements, demonstrating high accuracy of both 3D-CT protocols. CONCLUSIONS: 3D-CT volume rendering images using craniometric measurements can be used for anthropological studies involving craniofacial applications.

Aged↗

A unified method for calculating the center of pressure during wheelchair propulsion.

The measurement of the center of pressure (COP) has been and continues to be a successful tool for gait analysis. The definition of a similar COP for wheelchair propulsion. however, is not straightforward. Previously, a COP definition similar to that used in force plate analysis had been proposed. Unfortunately, this solution has the disadvantage of requiring a separate COP definition for each plane of analysis. A definition of the generalized center of pressure (GCOP) which is consistent in all planes of analysis is derived here. This definition is based on the placement of a force-moment system, equivalent to the force-moment system at the hub, on a line in space where the moment vector (wrench moment) is parallel to the force vector. The parallel force-moment system is then intersected with three planes defined by anatomical landmarks on the hand. Data were collected using eight subjects at propulsion speeds of 1.34 m/s and 2.24 m/s (1.34 m/s only for subject 1, 0.894 m/s and 1.79 m/s for subject 8). Each subject propelled a wheelchair instrumented with a SMARTwheel. A PEAK 5 video system was used to determine the position of anatomical markers attached to each subject's upper extremity. The GCOP in the transverse plane of the wrist formed clusters for all subject's except subject 2 at 1.34 m/s. The clustering of the GCOP indicates that the line of action for the force applied by the hand is approximately perpendicular to the transverse plane through the wrist. When comparing the magnitude of the moment vector part of the wrench with the moment of the force vector of the wrench about the hub, the wrench moment is approximately an order of magnitude smaller. This indicates that the role of the wrist for wheelchair propulsion is primarily to stabilize the force applied by the arm and shoulder.

Biomechanical Phenomena↗

Three-dimensional Bolton-Brush Growth Study landmark data: ontogeny and sexual dimorphism of the Bolton standards cohort.

OBJECTIVE: The treatment of craniofacial reconstructive surgery patients may benefit from comparison to average referent three-dimensional landmark data. These data may be useful for diagnosis, treatment planning, prosthetic design, or outcomes assessment. With regard to subadult patients, we hypothesize that the pattern of ontogenetic shape change of same sex, same ethnicity, referent populations will show gross uniformity. We present a preliminary shape analysis of 50 three-dimensional landmarks derived from 317 Bolton-Brush Growth Study biorthogonal image pairs. We determine which landmarks can be collected from scanned radiographs reliably by four operators for the precisely locatable points, ontogenetic trends in landmark configuration shape change, and patterns of sexual dimorphism. PARTICIPANTS: Participants were Bolton standards individuals (16 male and 16 female) who contributed biplane cephalograms seven or more times with annual or greater spacing between ages 3 and 18 years. DESIGN: After removing outliers, we searched for ontogenetic heterogeneity, including sexual dimorphism and within sex-specific Procrustes coordinate shape spaces. RESULTS: A cut-off of 4.3-mm interoperator error left 32 landmarks in our analysis. Three different approaches (principal component analysis, age-trend analysis, and principal components of age residuals) all found no patterns of individual variation around sex-specific average trends of shape change. Male shape change peaks at age 15, a correlate of the growth spurt. CONCLUSIONS: Simultaneous frontal and lateral anatomic landmark identification improves three-dimensional localization reliability. Three-dimensional craniodental shape change from ages 8 to 18 within the Bolton standards presents little heterogeneity. Considerations of ethnicity aside, these may be initial grounds for use of these data as a normative referent.

Adolescent↗

Distinction between paraclinoid and cavernous sinus aneurysms with computed tomographic angiography.

OBJECTIVE: To examine the reliability of using the optic strut as a landmark in computed tomographic (CT) angiography, to differentiate between intradural and extradural (cavernous sinus) aneurysms involving the paraclinoid segment of the internal carotid artery (ICA). METHODS: Microanatomic dissections were performed with five cadaveric heads (10 sides), to establish the relationships of the optic strut to the cavernous sinus and the ICA. Results from these anatomic studies were compared with intraoperative and CT angiographic findings for four patients with nine intracranial aneurysms involving the paraclinoid segment of the ICA. RESULTS: The inferior boundary of the optic strut accurately localized the point at which the ICA pierced the oculomotor membrane (proximal dural ring) and exited the cavernous sinus. The optic strut and its relationship to the ICA could be well observed on CT angiograms. During surgery, six of six aneurysms that arose distal to the optic strut were identified intradurally and were successfully clipped. Conversely, all aneurysms that arose proximal to the optic strut were observed to lie within the cavernous sinus. An aneurysm at the optic strut was within the clinoid segment or interdural, between the proximal and distal rings. CONCLUSION: The optic strut, as identified with CT angiography, provided a reliable anatomic landmark for accurate discrimination between intradural and extradural (cavernous sinus) aneurysms.

Adult↗

The role of the medial wall and its anatomical variations for bimanual antiphase and in-phase movements.

The medial wall of the frontal cortex is thought to play an important role for bimanual coordination. However, there is uncertainty regarding the exact neuroanatomical regions involved. We compared the activation patterns related to bimanual movements using functional magnetic resonance imaging in 12 healthy right-handed subjects, paying special attention to the anatomical variability of the frontal medial wall. The subjects performed unimanual right and left and bimanual antiphase and in-phase flexion and extension movements of the index finger. Activation of the right supplementary motor area (SMA) proper, right and left caudal cingulate motor area (CMA), and right and left premotor cortices was significantly stronger during bimanual antiphase than bimanual in-phase movements, indicating an important function of these areas with bimanual coordination. A frequent anatomical variation is the presence of the paracingulate sulcus (PCS), which might be an anatomical landmark to determine the location of activated areas. Seven subjects had a bilateral, three a unilateral right, and two a unilateral left PCS. Because the area around the PCS is functionally closer coupled to the CMA than to the SMA, activation found in the area around the PCS should be attributed to the CMA. With anatomical variations such as the presence of a PCS or a vertical branch of the cingulate sulcus, normalization and determination of the activation with the help of stereotaxic coordinates can cause an incorrect shift of CMA activation to the SMA. This might explain some of the discrepancies found in previous studies.

Adult↗

Accuracy of spinal navigation for magerl screws.

The influence of a protocol of preoperative computed tomography scanning and a special registration technique was assessed on the accuracy of navigation for implanting Magerl C1-C2-screws. The use of navigation systems for implanting Magerl screws could help to decrease the risk of complications and to reduce the required skin incision. Two parameters conceivably affecting the accuracy are the protocol of preoperative computed tomography scanning and the registration technique. Four cervical spine segments of human cadavers were scanned with two computed tomography protocols. Registration was done based on anatomic landmarks or using a specially designed percutaneous registration device. For the accuracy check, the pointer tip was placed exactly on the markers. The displayed distance on the monitor was referred as an estimate of accuracy. Varying the computed tomography protocol did not significantly affect the accuracy. The mean accuracy was improved from 3 mm after anatomic pair-point matching to 1.5 mm after matching using the percutaneous registration device. The accuracy obtainable seems to be sufficient for implanting Magerl screws by using frameless stereotactic navigation. Three-millimeter slice thickness and 2-mm table increment is a proper protocol for preoperative computed tomography scanning. Fiducial markers improve the accuracy significantly.

Arthritis, Rheumatoid↗

Resurfacing elbow prosthesis: shape and sizing of the humeral component.

The sizing and dimensioning of a new unconstrained elbow prosthesis makes use of a geometric axis for humeral articulating surface definition, an axis which is precisely positioned with respect to extra-articular anatomical landmarks. The geometry of the joint was determined by a slicing and digitization technique. It was found that for the humerus an axisymmetric surface is evident and that there exists a centroidal axis which is mostly linear except for a portion at the posterior lateral flange of the trochlea. Sizing studies were carried out on dry bone anatomical specimens and, using a standardized X-ray technique, on the elbows of volunteer subjects. Seven dimensions were chosen for statistical analysis of the joint. A multi-variate normal distribution model, using only the first principal component was found to account for 70% of the variance; components 2 and 3 explained a further 19%. From this analysis, one series of three and five sizes of prosthetic dimensions were established for 95% overall coverage of population.

Biomedical Engineering↗

The anterior layer of Denonvilliers' fascia: a common misconception in the laparoscopic prostatectomy literature.

PURPOSE: Incision of the anterior layer of Denonvilliers' fascia is commonly cited as a key step in successful dissection of the vasa deferentia and seminal vesicles from the posterior bladder neck during laparoscopic radical prostatectomy. However, anatomical descriptions do not support the presence of Denonvilliers' fascia anterior to the seminal vesicles. To address this inconsistency we performed a detailed anatomical study of tissue planes encountered during laparoscopic dissection of the posterior bladder neck. MATERIALS AND METHODS: To grossly characterize the tissue planes encountered during laparoscopic posterior bladder neck dissection, ex vivo dissections were performed on 4 separate cystoprostatectomy specimens. Biopsies of the representative areas were obtained from 20 consecutive laparoscopic radical prostatectomy specimens by 2 dedicated uropathologists. RESULTS: Following incision into the posterior bladder neck mucosa, longitudinally oriented fibers were readily visualized, extending from bladder neck to prostate base. Histologically this anatomical landmark represents the fusion of 2 separate tissue layers, that is an inner lamella composed of longitudinally disposed smooth muscle fibers in continuation with the longitudinal fascia of the bladder detrusor (medial fascicle of the detrusor running in between the ureters) and an outer lamella composed of fibroadipose tissue in continuation with the bladder adventitia. CONCLUSIONS: Our anatomical and histological analysis refutes the prevailing belief in the laparoscopic literature that the longitudinal muscle fibers identified during dissection of the posterior bladder neck represent the anterior layer of Denonvilliers' fascia. They correspond to the posterior longitudinal fascia of the detrusor muscle that is externally upholstered by the bladder adventitia.

Fascia↗

Ultrasound-guided cannulation versus the landmark-guided technique for acute haemodialysis access.

BACKGROUND: The correct placement of large-bore venous catheters plays an important role in the management of haemodialysis patients. Whilst the procedure for landmark-based placement of these catheters is well known, the technique is not without significant morbidity and mortality. Complications include arterial puncture, haematoma, and pneumothorax. The procedure may be further complicated in these patients by venous thrombosis and abnormal vein position from multiple previous attempts at venous access. METHODS: Data on the use of ultrasound guidance versus anatomical landmarks for the placement of internal jugular vein (n = 69) and femoral vein (n = 30) dialysis access was retrospectively analysed over a 13-month period. Data collected included age, sex, duration on dialysis, number of vein cannulation sets required, number of attempts for successful cannulation, salvage of failed cannulation using landmark-based technique by ultrasound guidance, and the complication rate. RESULTS: Internal jugular vein cannulation using ultrasound was ultimately successful in 96.7% compared to 82% in the landmark group. The vein was entered on the first attempt in 83.3% of patients with ultrasound compared to 35.9% of the landmark group (P < 0.0001). Seven patients in whom the landmark technique was unsuccessful had access placed under ultrasound guidance. There were fewer carotid artery punctures in the ultrasound group (7.7 versus 0%, P = n.s.). In the femoral vein group, the vein was entered on the first attempt in 85.7% of patients with ultrasound compared to 56.25% of the landmark group (P = n.s.). CONCLUSIONS: The use of ultrasound guidance is associated with fewer complications and is more likely to lead to cannulation of the vein at the first attempt in haemodialysis patients.

Carotid Artery Injuries↗

Pilot study of dynamic cine CT angiography for the evaluation of abdominal aortic aneurysms: implications for endograft treatment.

PURPOSE: To utilize 40-slice electrocardiographically (ECG)-gated cine computed tomographic angiography (CTA) to characterize normal aortic motion during the cardiac cycle at relevant anatomical landmarks in preoperative abdominal aortic aneurysm (AAA) patients. METHODS: In 10 consecutive preoperative AAA patients (10 men; mean age 78.8 years, range 69-86), an ECG-gated CTA dataset was acquired on a 40-slice CT scanner using a standard radiation dose. CTA quality was graded and scan time was measured. Pulsatility measurements at multiple relevant anatomical levels were performed in the axial plane. Changes in aortic circumference were determined for both the aortic wall and the luminal diameter. RESULTS: All 10 CT scans were of good quality. All patients could be scanned in 14 to 33 seconds (mean 21). At each anatomical level measured, there was a 2.2- to 3.4-mm increase in the aortic wall circumference per cardiac cycle. A similar increase was observed in luminal circumference, with a 2.4- to 3.6-mm increase per cycle. CONCLUSION: This study introduces the concept of dynamic cine CTA imaging of aortic motion, providing insight into the pathophysiology of abdominal aortic and iliac pulsations. Patients with AAAs selected for EVAR demonstrate changes in aortic circumference with each cardiac cycle that may have consequences for endograft sizing and future design. The potential for graft migration, intermittent type I endoleak, and poor patient outcome following EVAR can be anticipated. Complex aortic dynamics deserve increased scrutiny in an effort to prevent potential complications.

Aged↗

Accuracy of stereolithographic models of human anatomy.

A study was undertaken to determine the dimensional accuracy of anatomical replicas derived from X-ray 3D computed tomography (CT) images and produced using the rapid prototyping technique of stereolithography (SLA). A dry bone skull and geometric phantom were scanned, and replicas were produced. Distance measurements were obtained to compare the original objects and the resulting replicas. Repeated measurements between anatomical landmarks were used for comparison of the original skull and replica. Results for the geometric phantom demonstrate a mean difference of +0.47 mm, representing an accuracy of 97.7-99.12%. Measurements of the skull produced a range of absolute differences (maximum +4.62 mm, minimum +0.1 mm, mean +0.85 mm). These results support the use of SLA models of human anatomical structures in such areas as pre-operative planning of complex surgical procedures. For applications where higher accuracy is required, improvements can be expected by utilizing smaller pixel resolution in the CT images. Stereolithographic models can now be confidently employed as accurate, three-dimensional replicas of complex, anatomical structures.

Humans↗

Subfascial and submuscular methods of temporal muscle dissection and their relationship to the frontal branch of the facial nerve. Technical note.

The microsurgical anatomy of the temporal and zygomatic branches of the facial nerve are presented along with related local vasculature (frontal and parietal branches of the superficial temporal artery [STA]) as encountered when using subfascial and submuscular temporal muscle dissection techniques for anterolateral craniotomies. Twenty sides were studied in 10 cadaveric specimens that had been previously injected with latex. The rami of the temporal and zygomatic branches of the facial nerve and branches of the STA were dissected out through pterional and orbitozygomatic approaches by using a submuscular or subfascial temporal muscle dissection technique. The three rami of the temporal branch of the facial nerve (the auricularis, frontalis, and orbicularis) were found to run within the galeal plane of the scalp. The zygomatic branch of the facial nerve was found to course deeper than the most caudal extension of the galea, known as the superficial musculoaponeurotic layer. The frontal branch of the STA served as an important landmark for the subfascial or submuscular dissections because excessive reflection of the scalp flap inferior to the level of this vessel would inadvertently injure the frontalis branch of the facial nerve. Subfascial and submuscular dissections of the temporal muscle offer an alternative to the interfascial technique during anterolateral craniotomies. Scalp and temporal dissection performed with careful attention to anatomical landmarks (frontal branch of the STA and the suprafascial fat pad) provides a safe and expeditious alternative to the traditional interfascial technique.

Adipose Tissue↗

Precision, repeatability, and validation of the localization of cranial landmarks using computed tomography scans.

Computed tomography (CT) has brought to the craniofacial surgeon a three-dimensional representation of internal structures. CT scans provide visualization of anatomy for preoperative planning and postoperative evaluation. Beyond visualization, however, a CT scan enables assessment of measurements useful to clinicians and basic scientists. All measurement systems used with CT require the ability to accurately locate regions of interest on the image (i.e., areas, volumes, outlines, curves, surfaces, points). This study evaluates the precision and repeatability of locating anatomic landmarks in three dimensions on CT slice images, and validates these locations using an established measurement system. The average error of landmark position is always less than 0.5 mm and for some landmarks error is negligible. Repeatability studies show that less than 2% of the total variance in our data is due to measurement inaccuracy. Although data collected from CT scans are internally consistent, validation results caution the use of CT data in combination with data collected using calipers or other direct means of measurement.

Adult↗