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PubMedDate not supplied

Variability of the postauricular muscle complex: analysis of 40 hemicadaver dissections.

BACKGROUND: The postauricular area is often explored by reconstructive and otologic surgeons. We previously reported on the use of postauricular tissues as a graft for wrapping hydroxyapatite implants in orbital reconstruction. This procedure reduced the incidence of implant exposure, while achieving acceptable cosmetic results. Although much is known about the postauricular area, muscle and fascial relationships and potential variations in anatomy remain ill defined. OBJECTIVES: To identify and analyze variations in the patterns of the postauricular muscle complex (PMC) and to study the relationships of the fascial contributions from the components that make up the PMC. METHODS: Dissections were performed using 40 fresh specimens. Muscular and fascial components of the PMC were dissected, analyzed, and photographed. RESULTS: The PMC receives contributions from the occipitalis and trapezius muscles, the deep temporal and sternocleidomastoid fasciae, and the superior and posterior auricular and platysma muscles. Major contributors to the PMC were present in every specimen. Minor contributors were more variable in their presence and contributions. The posterior auricular muscle was identified as having several muscle bundles in 1 specimen and absent in 2 specimens (5%). The occipitalis fascia was seen to insert superior to the auricle and to blend with the deep temporal fascia in 3 cases (7%). The platysma muscle contributed to the PMC in 8 cases (20%). CONCLUSIONS: This study demonstrated important variations in the presence and contributions of 7 previously known muscular structures and their role in forming the PMC. Seven distinct patterns are identified, and the potential clinical implications of these anatomical variations are illustrated.

Cadaver↗
PubMed2004

Computational anatomy and neuropsychiatric disease: probabilistic assessment of variation and statistical inference of group difference, hemispheric asymmetry, and time-dependent change.

Three components of computational anatomy (CA) are reviewed in this paper: (i) the computation of large-deformation maps, that is, for any given coordinate system representations of two anatomies, computing the diffeomorphic transformation from one to the other; (ii) the computation of empirical probability laws of anatomical variation between anatomies; and (iii) the construction of inferences regarding neuropsychiatric disease states. CA utilizes spatial-temporal vector field information obtained from large-deformation maps to assess anatomical variabilities and facilitate the detection and quantification of abnormalities of brain structure in subjects with neuropsychiatric disorders. Neuroanatomical structures are divided into two types: subcortical structures-gray matter (GM) volumes enclosed by a single surface-and cortical mantle structures-anatomically distinct portions of the cerebral cortical mantle layered between the white matter (WM) and cerebrospinal fluid (CSF). Because of fundamental differences in the geometry of these two types of structures, image-based large-deformation high-dimensional brain mapping (HDBM-LD) and large-deformation diffeomorphic metric matching (LDDMM) were developed for the study of subcortical structures and labeled cortical mantle distance mapping (LCMDM) was developed for the study of cortical mantle structures. Studies of neuropsychiatric disorders using CA usually require the testing of hypothesized group differences with relatively small numbers of subjects per group. Approaches that increase the power for testing such hypotheses include methods to quantify the shapes of individual structures, relationships between the shapes of related structures (e.g., asymmetry), and changes of shapes over time. Promising preliminary studies employing these approaches to studies of subjects with schizophrenia and very mild to mild Alzheimer's disease (AD) are presented.

Algorithms↗
PubMed2006

[Anatomy, special features and angiographic assessment of the coronary sinus].

The endovenous approach for left ventricular lead implantation can be used in most patients. A complete angiography of the coronary vein will increase the success rate of lead implantation. From a technical point of view, attention should be focused on anatomical variation, which leads to a higher number of complications like dissection or perforation of the vessel. However, in a number of cases a left verticular lead must be implanted epimyocardial due to anatomical reasons.

Coronary Angiography↗
PubMed2002

Recurrent laryngeal nerve in thyroid surgery: a critical appraisal.

BACKGROUND: Identification and preservation of the recurrent laryngeal nerve (RLN) is of major concern in surgery of the thyroid gland. The purpose of this study was to review the surgical anatomy of the nerve and to describe its relationship to other important structures. METHODS: A total of 325 patients were accrued in this prospective non-randomized study from January 1999 to December 2000. All patients who had total, subtotal and hemithyroidectomies were included in this study. Each side of the thyroid gland was considered as a separate unit in the analysis of the results. RESULTS: Two hundred and seventy-six patients had thyroidectomies as their primary operation, while 49 patients had them as a reoperative procedure. There were 276 women and 46 men (6:1 female to male ratio) with a mean age of 43.1 years (range: 10-84 years). The total number of dissections was 502. The RLN was clearly identified in 491 (97.8%) dissections: single trunk in 323 dissections (65.8%), two extralaryngeal branches in 164 dissections (33.4%), and three extralaryngeal branches in three dissections (0.6%). One non-recurrent laryngeal nerve was encountered (0.2%) in the series. The proximity of the RLN to the inferior thyroid artery (ITA) was noted in 444 (90.4%) dissections: 372 (83.8%) nerves were described to be posterior and intertwined between the branches of the ITA, and in 72 (16.2%) RLNs, they were observed to be anterior to the ITA. The close association of RLN to an enlarged tubercle of Zuckerkandl was documented in 381 dissections (73.7%). A total of 231 RLNs (60.8%) was seen in the tracheoesophageal groove, 18 (4.9%) nerves were observed to be lateral to the trachea, and in 109 (28.3%), they were posterior in location. Of concern in 23 (6.0%) dissections the RLN was on the anterior surface of the thyroid gland, which is at highest risk of injury before curving down to pass behind the tubercle of Zuckerkandl. It appears that the anterior course of the RLN was seen more often in the reoperative procedures to the thyroid gland (20%). CONCLUSIONS: Although various methods of localizing the RLN have been described, surgeons should be aware of the variations and have a thorough knowledge of normal anatomy in order to achieve a high standard of care. This will ensure the integrity and safety of the RLN in thyroid surgery. The anatomical variation may be minor in degree, but is of great importance as it may affect the outcome of the surgery and the patient's quality of life.

Adolescent↗
PubMed1984

Head position for transcranial temporomandibular joint radiographs.

Proper angulation is important for clear transcranial TMJ radiographs. Because of individual anatomic variations, it is essential that a variable head positioner device be used. Variations in the vertical and horizontal angulation of the x-ray beam will affect the relative position of the TMJ, the petrous line, and the posterior clinoid process (Fig. 11). If other anatomic structures are superimposed on the condyle and fossa, interpretation of normal or pathologic anatomy may not be possible.

Head↗
PubMed1989

Variations of the flexor digitorum superficialis of the small finger.

Normal functional variations of the flexor digitorum superficialis were clinically determined by use of the standard and modified superficialis flexion tests in 50 normal subjects. Forty hands of 20 cadavers were dissected to correlate the anatomic variations with the clinical findings. A flexor digitorum superficialis-independent pattern was found 58% of the time. A flexor digitorum superficialis-common pattern was found 21% of the time. A flexor digitorum superficialis-absent pattern was found 21% of the time. The right and left hands were asymmetric 26% of the time. All cadaver hands had a flexor digitorum superficialis tendon present in the palm and finger. The variability in flexor digitorum superficialis function may be explained by interconnections between the flexor digitorum superficialis of the small finger and either the flexor digitorum superficialis of the ring finger or the flexor digitorum profundus of the small finger.

Fingers↗
PubMed2006

Persistent left superior vena cava with absent right superior vena cava: morphological CT features and clinical implications.

Here we report a rare case of the persisting left superior vena cava with simultaneous absence of the right superior vena cava. This central venous variation has been identified during a routine chest CT scan as follow-up after colonic cancer in an asymptomatic patient with no previous history of heart diseases. Morphological features of this variation are illustrated on axial CT images and 3D image reconstructions. This anomaly occurs in 0.1% of the general population. In presence with the right superior vena cava it is the most common anatomical variation in the central venous system with a reported occurrence of 0.2-8%. Such condition can be associated with additional congenital cardiovascular malformations and heart diseases or rhythm abnormalities. Diagnosis can be difficult and is often achieved incidentally since hemodynamics in these patients can be normal and clinical symptoms are mostly absent. Important clinical implications include difficulties in central venous access or cardiac pacemaker placement as well as management consequences in cardiothoracic surgery. In conclusion clinicians should be aware of this anomaly and their clinical relevance to avoid possible complications.

Aged↗
PubMed1999

How easily do topical antibiotics pass through tympanostomy tubes?--an in vitro study.

BACKGROUND: Despite potential ototoxicity, eardrops containing aminoglycosides remain in widespread use in the presence of indwelling tympanostomy tubes (grommets). It is unclear how readily they pass into the middle ear during administration, nor whether this is affected by middle ear secretions. MATERIALS AND METHODS: The trans-tympanic pressure required to force antibiotic solutions through a tympanostomy tube in an artificial middle ear model was investigated with six ototopical preparations and two sizes of tube. To assess the effect of middle ear secretions, tympanostomy tubes removed from patients ears were investigated in addition to new tubes. The intra-canal pressure generated during tragal massage was also measured. RESULTS: Pressures required for leakage of solutions differed significantly between solutions (P=0.001) and tube sizes, smaller lumen tubes requiring higher trans-tympanic pressure for leakage to occur. The presence of middle ear secretions reduced the pressure required for leakage of solution. Tragal massage generated pressures of over 20 cm of H20 which would be enough to force solution into the middle ear in all tube/solution combinations. DISCUSSION: Some antibiotic solution is likely to leak into the middle ear during most applications of antibiotic solution. Although the risk is small, this suggests the possibility of ototoxicity, previously demonstrated in animal experiments. The relatively low incidence of this occurrence in clinical practice is thought to be related to inter-species anatomical variations.

Administration, Topical↗
PubMed1989

Behavioral responses to novelty and structural variation of the hippocampus in mice. II. Multivariate genetic analysis.

On the basis of results from lesion studies in rodents, covariations are expected to exist between naturally-occurring heritable variations in hippocampal morphology and exploratory behavior elicited by novel surroundings. For this reason, we set up a full diallel cross between five inbred mouse strains and analyzed the behavioral and the hippocampal anatomical variation in male animals from this cross. Employing a bivariate extension of the diallel-cross analysis, estimates were obtained for the phenotypical, environmental, and genetical correlations between the phenotypes studied. A factor analysis performed on the matrix of additive-genetic correlations revealed that variations in the size of the intra- and infrapyramidal mossy fiber terminal fields (iip-MF) are negatively related to open-field exploration and novelty-induced fear. These results indicate that having larger iip-MF projections promotes the collection and processing of information about a novel environment, entailing lower levels of exploration and fear.

Animals↗
PubMed2002

Evolution of virtual CT laparoscopy for preoperative imaging in laparoscopic cholecystectomy.

The purpose of this study was to determine the feasibility of virtual endoscopy, named as "virtual CT laparoscopy", in the hepatobiliary system prior to laparoscopic cholecystectomy. We applied this technique to 28 patients suspected of having biliary disease. These images were compared and analyzed qualitatively based on visualization of the structures critical to operative cholangiography and surgical findings. Twenty-four patients, who underwent laparoscopic cholecystectomy, were evaluated as follows: the common bile duct and the hepatic duct were adequately visualized in 23 (96%) of the 24 patients, the cystic duct in 21 (88%), the gallbladder opacification in 20 (83%), the liver inferior surface in 20 (83%). Four patients had anatomic variations detected virtual CT laparoscopy and were proven by operative cholangiography and surgical findings. We emphasize that our new technique may contribute to the laparoscopy during surgery as the aid of understanding of anatomical structures in these organs.

Adult↗
PubMed2006

Variations of the course of the upper trunk of the brachial plexus and their clinical significance for the thoracic outlet syndrome: a study on 93 cadavers.

The aim of this study is the recording of the variations of the course of the upper trunk (UT) of the brachial plexus (BP) and their clinical significance for the thoracic outlet syndrome (TOS) and the anesthetic blockade of the BP. Five different anatomical variations of the course of the UT of the BP, in relation to the anterior scalene muscle (ASM), were observed in 24 out of the 186 sides of the 93 cadavers we studied (12.9%). The C5 root was passing anteriorly to the ASM in six cases. The UT was located anteriorly to the ASM in four cases and was perforating the ASM's belly in 12 cases. In one cadaver, the ASM was double and the UT was passing between the two bellies of the double ASM. Finally, in another cadaver, the C5 root was found to be anterior to the anterior scalene muscle, while the C6 root was perforating the ASM's belly. These variations are predisposing factors for the TOS; they cause specific symptomatology and require a different surgical approach in comparison with other causes of the syndrome. Moreover, knowledge of these is important during the performance of the anesthetic blockade of the BP.

Adult↗
PubMed1987

Microsurgical anatomy of the pituitary gland and the sellar region. 2. The bony structures.

Measurements of the sella turcica (depth, length, width, volume, thickness of the floor, intraclinoid distance, length of tuberculum sellae) were made in cadaver sphenoid blocks, skulls, and in patients undergoing transsphenoidal surgery. Variations in the sphenoidal septae, sinuses and bulging of surrounding structures (carotid arteries and optic nerves) were studied. Results were compared with observations made during surgery and with data reported in the literature. Anatomic variations of the sella turcica and sphenoid sinus may complicate surgical intervention in the region of the sella turcica. However, these variations were never, in our experience, the cause for interruption of transsphenoidal surgery.

Cadaver↗
PubMed1995

[The anatomy of the maxillary ostium and the middle meatus antrostomy].

Serial cadaver dissections were performed and the anatomy of the natural ostium of the maxillary sinus and its adjacent structures observed. The results showed obvious anatomic variations. In most cases, the maxillary ostium was located in the infundibulum, directly under the orbit. The average distance was 1.1 cm from the maxillary ostium to the anterior maxillary wall, showing the anatomic relationship of the maxillary ostium with the nasolacrimal duct. The close anatomic relationship between the antronasal channel and orbit was demonstrated by radiography. A retrospective review of 70 middle meatal antrostomies was conducted and discussed. The anatomy of the antronasal channel should be well understood by an endoscope sinus surgeon in order to perform the middle meatal antrostomy without injuring the orbit and nasolacrimal duct.

Endoscopy↗
PubMed2003

Dual responses of tissue partial pressure of oxygen after functional stimulation in rat somatosensory cortex.

To compare the spatial heterogeneity of brain tissue partial pressure of oxygen (pO(2)) among local brain regions, we focused on functional and anatomical variations in rat somatosensory cortex. Tissue pO(2) was measured by using an oxygen microelectrode with high spatio-temporal resolution, and investigated in three somatosensory areas including hindlimb (HL), forelimb (FL), and trunk region (Tr). Their anatomical structures were determined with histological techniques (Nissl stain). In addition to the measurement of baseline tissue pO(2), we examined temporal shifts in tissue pO(2) distribution elicited by functional stimulation using the brushing stimulation to the hindlimb, forelimb, and trunk regions of the body. We observed that average tissue pO(2) in the Tr (14+/-10 Torr) was significantly lower than those in the HL (25+/-13 Torr) and FL (24+/-13 Torr). Such regional differences in tissue pO(2) were closely related to the cytoarchitectonic variations among these three areas. In addition, the functional stimulation enlarged the regional differences in the pO(2) depending on each somatosensory area; the pO(2) in the HL increased by 3.6+/-2.9% after the stimulation to hindlimb, whereas that in the Tr decreased by -2.9+/-2.5% after the stimulation to trunk region. Such dual responses of tissue pO(2) (i.e. increase or decrease) after the functional stimulation to the corresponding body regions may provide a criterion to clinically predict regions susceptible to tissue hypoxia, because considerable decrease in tissue pO(2) occurred in the Tr showing the lowest baseline pO(2).

Animals↗
PubMed2001

Heterogeneous control of blood flow amongst different vascular beds.

The control and maintenance of vascular tone is due to a balance between vasoconstrictor and vasodilator pathways. Vasomotor responses to neural, metabolic and physical factors vary between vessels in different vascular beds, as well as along the same bed, particularly as vessels become smaller. These differences result from variation in the composition of neurotransmitters released by perivascular nerves, variation in the array and activation of receptor subtypes expressed in different vascular beds and variation in the signal transduction pathways activated in either the vascular smooth muscle or endothelial cells. As the study of vasomotor responses often requires pre-existing tone, some of the reported heterogeneity in the relative contributions of different vasodilator mechanisms may be compounded by different experimental conditions. Biochemical variations, such as the expression of ion channels, connexin subtypes and other important components of second messenger cascades, have been documented in the smooth muscle and endothelial cells in different parts of the body. Anatomical variations, in the presence and prevalence of gap junctions between smooth muscle cells, between endothelial cells and at myoendothelial gap junctions, between the two cell layers, have also been described. These factors will contribute further to the heterogeneity in local and conducted responses.

Animals↗
PubMed2006

Basilar expansion of the human sphenoidal sinus: an integrated anatomical and computerized tomography study.

Basilar expansion of the sphenoidal sinus (BESS) was studied in order to demonstrate its critical relevance in endoscopic or microscopic endonasal surgical interventions, including access to the sphenoidal sinus itself or in transsphenoidal pituitary approaches. Direct evaluation of anatomical specimens (25 dry skulls and 25 formalin-fixed hemi heads) and the use of computerized tomography (CT) (50 dry skulls and 750 patients) showed a high BESS frequency (69%). The authors considered BESS to be critical when the posterior wall of the clivus was 2-mm thick and found a high incidence of this important anatomical variation (44%). This study also evaluated the relationship between the sinonasal septa, the clivus, and the internal carotid arteries, and a considerable regularity in the location of these structures was seen. The septa were anatomically related to the internal carotid arteries in 55% and to the clivus in 33% of the cases. In conclusion, the high frequency of critical BESS here described is relevant to endoscopic or microscopic endonasal surgical interventions, including access to the sphenoidal sinus itself or in transsphenoidal pituitary approaches.

Cranial Fossa, Posterior↗
PubMed2005

Duplex evaluation of venous insufficiency.

Duplex ultrasound is the most useful examination for the evaluation of venous valvular incompetence. Multi-frequency 4 to 7-MHz linear array transducers are typically used for this assessment of superficial and deep reflux. The examination is done with the patient standing and manual compression maneuvers are used to initiate reflux. Automatic rapid inflation and deflation cuffs may be used when a standard stimulus is needed. Cutoff values for reflux have been defined. Perforating veins must be identified and flow direction during compression recorded. When ulcers are present, duplex ultrasound is used to investigate veins of the ulcerated legs. Venous outflow obstruction is also studied by duplex ultrasound and chronic changes in deep and superficial veins following deep venous thrombosis noted. The main drawback in evaluation of chronic obstruction is inability to quantify hemodynamic significance. Anatomic variations in superficial and deep veins are common and their identification is necessary. Reporting results of duplex ultrasound studies must take into consideration the proper classification of venous disease as well as the new anatomic terms that have been accepted.

Humans↗