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PubMed2002

The tentorial notch: anatomical variation, morphometric analysis, and classification in 100 human autopsy cases.

OBJECT: Variations in the structure of the tentorial notch may influence the degree of brainstem distortion in transtentorial herniation, concussion, and acceleration-deceleration injuries. The authors examined the anatomical relationships of the mesencephalon, cerebellum, and oculomotor nerves to the dimensions of the tentorial aperture. On the basis of numerical data collected from this study, the authors have developed the first classification system of the tentorial notch and present new neuroanatomical observations pertaining to the subarachnoid third cranial nerve and the brainstem. METHODS: The mesencephalon was sectioned at the level of the tentorial edge in 100 human autopsy cases (specimens from 23 female and 77 male cadavers with a mean age at time of death of 42.5 years [range 18-80 years]). The following measurements were determined: 1) anterior notch width, the width of the tentorial notch in the axial plane through the posterior aspect of the dorsum sellae; 2) maximum notch width (MNW), the maximum width of the notch in the axial plane; 3) notch length (NL), the length of the tentorial notch from the superoposterior edge of the dorsum sellae to the apex of the notch; 4) posterior tentorial length, the shortest distance between the apex of the notch and the most anterior part of the confluence of the sinuses; 5) interpedunculoclival (IC) distance, the distance from the interpeduncular fossa to the superoposterior edge of the dorsum sellae; 6) apicotectal (AT) distance, the distance from the tectum in the median plane to a perpendicular line dropped from the apex of the tentorial notch to the cerebellum; 7) cisternal third nerve distance, the distance covered by the cisternal portion of the third cranial nerve; and 8) inter-third nerve angle, the angle between the two third cranial nerves. The quartile distribution technique was applied to all measurements. Mean values are presented as the means +/- standard deviations. Quartile groups defined by NL (mean 57.7 +/- 5.6 mm) were labeled long, short, and midrange, and those defined by MNW (mean 29.6 +/- 3 mm) were labeled wide, narrow, and midrange. Combining these groups into a matrix formation resulted in the classification of the tentorial notch into the following eight types: 1) narrow (15% of specimens); 2) wide (12% of specimens); 3) short (8% of specimens); 4) long (15% of specimens); 5) typical (24% of specimens); 6) large (9% of specimens); 7) small (10% of specimens); and 8) mixed (7% of specimens). The IC distance (mean 20.4 +/- 3.2 mm) was used to characterize brainstem position as prefixed (28% of specimens), postfixed (36% of specimens), or midposition (36% of specimens). The IC distance was correlated with the left and right cisternal third nerve distances (means 26.7 +/- 2.9 mm and 26.1 +/- 3.2 mm, respectively) and the inter-third nerve angle (mean 57.3 +/- 7.3 degrees). The exposed cerebellar parenchyma within the notch, the relationship between the brainstem and tentorial edge, and the brainstem position varied considerably among individuals. The cisternal third nerve distance, its trajectory, and its anatomical relation to the skull base also varied widely. Two anatomically distinct segments of the subarachnoid third cranial nerves were characterized with respect to the skull base as suspended and supported segments. CONCLUSIONS: The authors present a new classification system for the tentorial aperture to help explain variations in herniation syndromes in patients with otherwise similar intracranial pathological conditions, and responses to concussive and acceleration-deceleration injuries. The authors present observations not previously described regarding the position of the brainstem within the tentorial aperture and the cisternal portion of the third cranial nerves. A significant statistical correlation was discovered among specific morphometric parameters of the tentorial notch, brainstem, and oculomotor nerves. These findings may have neurosurgical implications in clinical situations that cause brainstem distortion. Additionally, this analysis provides baseline data for interpreting magnetic resonance and computerized tomography images of the tentorial notch and its regional anatomy.

Adolescent↗

PubMed1995

Arterial embolism from anatomical variation at the thoracic outlet.

Thoracic outlet syndrome (TOS) represents a constellation of symptoms arising from the compression of the neurovascular bundle as it exits the thorax. We report a unique case of multiple rare anatomical anomalies resulting in TOS manifested by distal arterial embolism. These anomalies include the combination of: (1) a unilateral right cervical rib, Gruber's type II (Gruber 1869), (2) nonunion of the first thoracic rib, (3) abnormal fibrous insertions of the anterior scalene muscle onto the epineurium of the brachial plexus and adventitia of the subclavian artery, (4) anterior position of the brachial plexus in relation to the third portion of the subclavian artery, and (5) the bifurcation of a single root of the phrenic nerve at the level of the anterior scalene muscle. This series of findings suggest an underlying developmental abnormality with a delayed onset of symptomatology consisting of the thoracic outlet syndrome.

Abnormalities, Multiple↗

PubMed2006

Pelvicaliceal anatomical variation between stone bearing and normal contralateral kidneys--does it have an impact on stone formation in pediatric patients with a solitary lower caliceal stone?

PURPOSE: We aimed to investigate the probable effect of pelvicaliceal anatomical differences between stone bearing and normal contralateral kidneys on the etiology of stone formation in children with a solitary lower pole caliceal stone. MATERIALS AND METHODS: We reviewed the clinical records of 25 pediatric patients who underwent SWL for a solitary lower caliceal stone and 15 healthy pediatric patients who served as controls. Lower pole IPA, IL and IW, together with other caliceal variables obtained from the pelvicaliceal anatomy of the stone bearing and contralateral normal kidneys of patients with urolithiasis, and both kidneys of the control group were measured based on excretory urography. Also, total pelvicaliceal volume for both kidneys was calculated. RESULTS: Mean LIPAs of stone bearing kidneys compared to the normal contralateral kidneys was more acute, equal and wider in 52%, 16% and 32% of the patients, respectively. Mean pelvicaliceal volumes of the stone forming and normal kidneys were 1,553.8 mm(3) (range 242 to 7,107) and 581.0 mm(3) (90 to 2,662), respectively, and there was statistical significance only in pelvicaliceal volumes between the stone bearing and contralateral normal kidneys (p <0.001). CONCLUSIONS: Our results reveal that IPA, IL and IW of calices do not have an effect on stone formation in pediatric patients. However, large pelvicaliceal volume seems to be a significant risk factor for stone formation in the lower calix, probably because it creates abnormal urodynamic and morphological features, especially when accompanied by other metabolic abnormalities.

Child↗

PubMed2001

Anatomical variation of the sphenomandibular ligament.

The sphenomandibular ligament, which is derived from the sheath of Meckel's cartilage, is a fibrous structure that passes between the spine of the sphenoid bone and the lingula of the mandible. Although anatomical texts provide basic descriptions of this structure, there are few published reports of the extent of its variability or its possible clinical implications. The aim of this study was to provide a detailed description of the nature and extent of anatomical variability in the sphenomandibular ligament of seven human cadavers. Dissections of sagittally sectioned heads were performed using a medial approach that involved displacement of the tongue and mucosal tissues in the oral cavity and oropharynx, then reflection of the medial pterygoid muscle. The ligaments ranged in shape from thin bands that descended for a short distance from the spine of the sphenoid to broad bi-concave ligaments with prominent insertions. The mylohyoid nerve was seen to pass behind the ligament in all specimens, emerging from the postero-inferior border of the mandibular attachment before running into the mylohyoid groove on the medial surface of the ramus. Lying in the pterygomandibular space, the ligament was surrounded by fascia, both structures presenting potential barriers to the diffusion of local anaesthetic solution if injected medially. The appearance of the lingula also varied, and did not seem to reflect the size of attachment of the ligament, suggesting an alternative explanation of lingula morphology, perhaps related to a continuation of the mylohyoid ridge and anterior border of the mylohyoid groove.

Humans↗

PubMed2004

[Anatomic variations of the cystic duct and its junction with the common hepatic duct].

The ductus cysticus is variable in the length, position and the site where it enters the ductus hepaticus communis--the cystohepatic junction. The investigations were carried out on 100 livers (50 anatomical preparations and 50 patients) adults of both sexes, randomized trial. Main methods of the research were: anatomical macrodissection and analysis of the clinical radiograms. The ductus cysticus were present as: flat--down course in 70%, flat--horizontal course in 2%, flat--ascendant course in 4%, curved in the shape "J" in 10%, curved in the shape "S" in 12% and curved in the shape "U" in 2%. The cystohepatic junction shows variations in topographic zones.

Cystic Duct↗

PubMed2000

Anatomical variations in the human paranasal sinus region studied by CT.

A precise knowledge of the anatomy of the paranasal sinuses is essential for the clinician. Conventional radiology does not permit a detailed study of the nasal cavity and paranasal sinuses, and has now largely been replaced by computerised tomographic (CT) imaging. This gives an applied anatomical view of the region and the anatomical variants that are very often found. The detection of these variants to prevent potential hazards is essential for the use of current of endoscopic surgery on the sinuses. In the present work, we have studied the anatomical variants observed in the nasal fossae and paranasal sinuses in 110 Spanish subjects, using CT in the coronal plane, complemented by horizontal views. We have concentrated on the variants of the nasal septum, middle nasal concha, ethmoid unciform process and ethmoid bulla, together with others of lesser frequency. The population studied showed great anatomical variability, and a high percentage (67%) presented one or more anatomical variants. Discounting agger nasi air cells and asymmetry of both cavities of the sphenoidal sinus, which were present in all our cases, the variations most often observed were, in order, deviation of the nasal septum, the presence of a concha bullosa, bony spurs of the nasal septum and Onodi air cells.

Adult↗

PubMed1998

Anatomical variations in pressures generated by pressure garments.

Pressure therapy is the predominant means for prophylaxis and treatment of hypertrophic scar. Despite this, there is little scientific evidence to support its use. This study examines the pressures generated by pressure garments in four subjects at 36 different anatomical sites chosen to represent the varying body geometry. Direct subdermal pressures were measured by an established method, though novel for this application. Pressure garments create a mean increase in subdermal pressures of 22.2 mmHg (range -10 to 102 mmHg). A significant objective difference exists in pressures generated at different anatomical sites. These differences correlate to local tissue compliance and to known areas of good clinical response and inversely correlate to the radius of anatomic curvature. The data suggest that pressures around 15 mmHg are required to effect a positive scar response and that close experienced monitoring of garments be performed.

Cicatrix↗

PubMed2005

The main hepatic anatomic variations for the purpose of split-liver transplantation.

BACKGROUND/AIMS: Variant hepatic anatomy must be recognized and appropriately managed during split-liver transplantation to ensure complete vascular and biliary supply to both grafts. The aim of this study was to demonstrate the importance of an assessment of the hepatic anatomical structures for the purpose of split-liver transplantation. MATERIAL AND METHODS: Human cadaveric livers (n = 60) were obtained during routine autopsies. The cadavers and the livers had to comply with the following requirements: (1) minimum age 18 years, (2) no liver pathology expected from medical history, and (3) no liver pathology noted at autopsy. Resections were carried out en bloc with liver, celiac trunk, left gastric artery, lesser omentum, superior mesenteric artery, and head of the pancreas. The main anatomical structures of the liver as hepatic artery, portal vein, biliary tree, and hepatic veins were dissected and correlated hepatic segments for the application of liver splitting. RESULTS: The right the median, and the left hepatic veins were unique, with in 59 (98.3%), 53 (88.3%) and 46 (76.3%) cases, respectively. The portal vein trunk divided into right and left branches in 59 (98.3%) cases. A median branch appeared in 9 (15.2%) cases and no bifurcation of the portal vein occurred in 1 (1.6%) case. The right and left hepatic ducts were multiple in 47 (78.3%) and 57 (95%) cases, respectively, however, the median, hepatic duct was unique in 16 (26.6%) cases. Examining the intrahepatic distribution of the right hepatic duct, we found 4 branches in 28 (59%) cases (segments V, VI, VII, and VIII) 2 branches in 11 (23%) cases, (segments V and VI) and 2 branches in 8 (17%) cases (segments VII and VIII). Fifty-seven cadavers had multiple left hepatic ducts. The intrahepatic dissection showed that the distribution of the major branches were toward hepatic segments II and III. Three separate branches of the left hepatic duct were found in 11 (19%) cases (segments II, III, and IV). Two intrahepatic ducts coming from hepatic segments V and VI drained separately into the left intrahepatic biliary tree in 1 (2%) case. The arterial supply of the liver was by right and left hepatic artery with only 9 (15%) cases there being median hepatic artery. The right hepatic artery, coming from the superior mesenteric artery, was present in 15 (25%) cases and a left hepatic artery originating from the left gastric artery in only 2 (3.3%) cases. The left hepatic artery had 2 exceptional origins, in 1 (1.6%) case coming directly from the abdominal aorta and in the other from the superior mesenteric artery. The right and left hepatic artery was accessory, in 11 (18.3%) and 2 (3.3%) cases, respectively. The right hepatic artery was dominant in 4 (6.6%) cases. The median hepatic artery was directed to segment IV in 6 (10%) cases and to segment II and III in 3 (4.9%) cases. CONCLUSION: The study showed that the technique of controlled liver splitting for transplantation in 2 recipients is an acceptable method to increase the number of liver allografts. The anatomical and technical details of the splitting procedure are critical for the success of this technique. Good graft function and avoidance of complications depend on each graft having an intact arterial and portal blood supply as well as biliary and venous drainage from all retained liver segments. The absence of a bifurcation of the portal vein is a rare anomaly and would certainly contraindicate a partition.

Adult↗

PubMed2000

Anatomical variations of landmarks for implantation at the cochlear nucleus.

A knowledge of the microanatomy of the cochlear nucleus complex and its variations is essential for successful implantation and for the design of stimulation devices. One hundred cerebellopontine angle specimens were dissected under surgical conditions using the Zeiss NC31 surgical microscope. The topographical anatomy of the exit of the vestibulocochlear nerve, the cochlear nucleus and the surface of the medulla and their relation to the surrounding structures was recorded and measured. The mean distances between the exits of the VIIth and VIIIth cranial nerves were 4.7 +/- 0.9 mm, between the VIIth and IXth 6.3 +/- 1.2 mm and between the VIIIth and IXth 5.5 +/- 1.0 mm. The visible area of the cochlear nucleus covered a square of 10.0 +/- 2.9 by 3.3 +/- 1.0 mm. A major AICA-loop had to be re-routed in 17 per cent of specimens. The taenia of the choroid plexus was present in 92 per cent and had to be cut in 51 per cent in order to enter the foramen of Luschka, that had a mean size of 3.5 by 2.0 mm. It was wide open in 24 per cent, open only after incision of the arachnoid in 53 per cent, functionally closed but opened by extensive dissection in 18 per cent and anatomically occluded in five per cent of the specimens. The typical straight vein at the cochlear nucleus leading to the entrance of the foramen of Luschka was found in 76 per cent of specimens. Constant anatomical landmarks are very helpful for finding the cochlear nucleus, but variations may endanger dissection and implantation in a remarkable number of cases.

Brain Stem↗

PubMed2002

Anatomic variations related to decompression of the common peroneal nerve at the fibular head.

Peroneal nerve decompression at the fibular head may be anticipated to be performed more often because lower extremity peripheral nerve surgery is used to restore sensation to the feet of diabetic patients. Although the basic concept of releasing the fascia of the peroneus longus is well-known, anatomic variants related to the peroneus muscle have been identified that must be included in the technique for decompression of this nerve. A comparison of these anatomic variants was done between a random selection of 29 cadavers (bilateral) and 65 patients who underwent unilateral peroneal decompression to treat symptoms of that compression. A fibrous band on the undersurface of the superficial head of the peroneus longus was found in 30% of the cadavers and it was found in 78.5% of the patients. The mean width of the band in cadavers was 9.1 mm and in patients it was 10.1 mm. A fibrous band on the superficial surface of the deep head of the peroneus longus was found in 43% of cadavers, and it was found in 20% of the patients. The soleus muscle origin was joined to the peroneus muscle origin in 9% of cadavers and it was noted in 6% of the patients. It is suggested that during surgical decompression of the common peroneal nerve at the fibular head, the surgeon be aware of these anatomic variants so that they may be released appropriately.

Decompression, Surgical↗

PubMed1990

Anatomical variation in mast cell nerve associations in the rat small intestine, heart, lung, and skin. Similarities of distances between neural processes and mast cells, eosinophils, or plasma cells in the jejunal lamina propria.

Several studies have indicated that mast cells occur in close proximity to enteric nerves in the gastrointestinal tract of rats, man, and other mammalian species, and such intimate associations have been proposed as one of the anatomical bases of communication between the immune and the nervous systems. However, the specificity of anatomical associations between enteric nerves and mast cells, as opposed to other bone marrow-derived or lymphoid cells normally present in mucosal sites, is unclear. We used transmission electron microscopy to quantify the distances between mast cells and neural processes (nerve terminals or axons) in the small intestinal mucosa, right atrium, skin, and pulmonary parenchyma of normal rats, and in the small intestinal mucosa and lung parenchyma of rats that had undergone hyperplasia of the mast cell populations in these sites as a result of infection with the nematode Nippostrongylus brasiliensis. In the jejunal mucosa of normal rats, 8.0% of mast cells occurred within 100 nm of neural processes and an additional 11.0% between 101 and 500 nm of these structures; the corresponding figures for eosinophils were 3.3% (N.S. vs. mast cell value) and 23.3% (p less than 0.05 vs. mast cell value) and for plasma cells were 8.5% and 14.6% (N.S. vs. mast cell values). In the right atrium, 1.2% of mast cells occurred within 100 nm and an additional 13.4% within 101 and 500 nm of neural processes, whereas no mast cells were observed within 500 nm of neural processes in the pulmonary parenchyma or ear skin. Infection with N. brasiliensis increased by 61% the proportion of mast cells within 500 nm of neural processes in the jejunal mucosa and resulted in the appearance of mast cells in close association with these structures in the jejunal muscularis propria, but had no effect on the proportion of mast cells within 100 or 500 nm of neural processes in the pulmonary parenchyma. Acetylcholine esterase staining demonstrated dense networks of neural processes in the three sites where some mast cells were closely associated with these structures (jejunal mucosa and muscularis, right atrium) but not in the pulmonary parenchyma or ear skin. Taken together, our findings indicate that mast cells occur in close proximity to neural processes in sites where these structures are abundant, but that anatomical associations as close as those between mast cells and neural processes can also occur between such structures and other bone marrow-derived cells (eosinophils) or lymphoid cells (plasma cells) resident in the small intestinal mucosa.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1990

Anatomical variations of the carotid bifurcation: implications for digital subtraction angiography and ultrasonography.

Intravenous digital subtraction angiography was used to determine prospectively the positional variations of the common carotid bifurcation in 100 consecutive patients with clinically suspected arteriosclerotic disease. The most common position (97/200, 48.5%) of the external carotid artery was anteromedial to the internal carotid artery. Position of the external carotid artery anterolateral to the internal carotid artery was noted in 26/200 (13%) bifurcations, but this anatomical variant was more common on the right (21/100) than on the left (5/100) (p less than 0.01). Practical implications may be drawn from this study. For digital subtraction angiography, the left anterior oblique view has to be considered the projection of choice and the right common carotid bifurcation is less likely to be adequately displayed than the left one; for duplex ultrasonography, optimal visualization is obtained from a posterolateral orientation of the transducer.

Adult↗

PubMed2003

[Anatomic variations in the brachial plexus trunks and nerve roots].

BACKGROUND: Deviations observed during operations triggered our effort to initiate an investigation concerning variations in the formation of brachial plexus. MATERIAL AND METHODS: In 50 cadavers of adult subjects the authors examined 100 brachial plexuses in order to detect incidence of neural variations. The participation of the C4 radix or Th2 radix as well as various variants from outlets of individual radices and their branches from the vertebral column to the variants in the formation of nerve trunks was investigated. The attention was devoted to their course, anastomoses, thickness and occasional absence. In addition to anatomical complexity and variability, attention is paid to motor innervation peculiarities in relation to diagnosis. The attention is paid to the mechanisms and morphological reasons in the origin of certain type of injuries. RESULTS: The prefixed type occurred in 24 cases (48%), the postfixed one in a singe case. In 25 cases (50%) 32 deviations were observed. The deviations were more frequent on the left side in 11 cases. CONCLUSION: The study made it possible to find out and describe exceptional, so far unpublished, anatomical deviations in the formation of nerve radices and trunks of brachial plexus.

Adult↗

PubMed2004

Digital innervation patterns following median or ulnar nerve laceration and their correlation to anatomic variations of the communicating branch between these nerves.

The midline of the ring finger is classically considered as the neural watershed between the median and ulnar nerve sensory territories on the palmar surfaces of the fingers. Variations of this division exist and may be explained by a communicating branch between the third and fourth common digital nerves. The palmar sensibility patterns of fingers were assessed with Semmes Weinstein filaments after either a complete median or an ulnar nerve transection in 43 patients. Eight out of nine observed sensibility patterns could be explained by known anatomic types and subtypes of the communicating branch. The type of communicating branch, but not its subtype, could be established in the one remaining pattern.

Adolescent↗

PubMed1996

The presence of arterial anatomical variations can affect the results of duplex sonographic evaluation of penile vessels in impotent patients.

PURPOSE: Since penile arterial communications are present in a significant percentage of impotent patients, we evaluated whether peak systolic cavernous blood velocity after intracavernous prostaglandin E1 injection might be different in patients with and without arterial variants. MATERIALS AND METHODS: Cavernous blood flow was assessed with echo color Doppler ultrasound before and after intracavernous injection of prostaglandin E1 in 63 impotent patients. The penile shaft was accurately evaluated to detect arterial anatomical variants. Clinical erectile response was assessed by visual inspection and palpation. RESULTS: Of 23 patients who obtained a full erection with full rigidity after prostaglandin E1 injection the cavernous peak blood velocities in 11 with penile arterial communications were significantly less than those in 12 without arterial communications. CONCLUSIONS: The generally accepted limit of normal for cavernous peak blood flow obtained after prostaglandin E1 injection (greater than 25 to 30 cm. per second) must be interpreted carefully because lower peak blood velocities may be found in subjects with a full erectile response if arterial communications are present.

Alprostadil↗

PubMed1999

An investigation into the impact of anatomical variation upon mean glandular dose produced within a standard breast.

By using the EGS4 Monte Carlo computer program the normalised mean glandular dose (MGD) was calculated for a breast model that is intended to reflect the composition of an "average" breast. The reliability of the calculation was established by comparing the predictions with previously published values for a breast model. The breast model used was then altered in order to reflect the possible extremes in glandular distribution that could occur within a compressed breast. These results show that the MGD could vary by up to a factor of four depending upon where the majority of glandular tissue is located within the breast. The impact of this variation in MGD upon risk assessment within mammography is then discussed.

Adipose Tissue↗

PubMed1989

[Interosseous dorsal artery of the first intermetatarsal space: anatomic variations and value in functional vascular studies].

The first dorsal metatarsal artery (MDA) is usually described as the last collateral branch of dorsalis pedis artery (DPA, which anastomoses with the lateral plantar branch of the posterior tibial artery (PTA). Doppler assessment on DMA of a flow does not always mean that DPA is free, but may show a functional plantar arch. The aim of this study was to determinate the patency rate of this plantar arch and to appreciate the part of DPA in the vascularisation of the foot. Anatomical descriptions were compared with our own dissections, (25 cadavers and 55 arteriographies in fetus), angiographic analysis and vascular plastic casts. The functional aspect of this study was made by Doppler examination of DMA using alternative or simultaneous compression of the main arteries of the ankle, until doppler curves were canceled. That was done on healthy volunteers and arteriosclerotic patients. The results show that, from the anatomical viewpoint, the plantar arch is almost always present, since it was found in 88% of adult pieces. Nevertheless, on Doppler examination, the plantar arch was found functional only in 64% of healthy people. The difference between the two rates emphasizes the fact that anatomical anastomosis are note always open, according to the subject and probably to the age. Looking after MDA permeability in patients with arteriosclerosis leads to point out the main vascular access to the foot, for limb salvage, and the leading part of distal anastomosis to keep good trophicity of the toes.

Adult↗

PubMed1999

Computed tomographic imaging to determine the frequency of anatomical variations in pneumatization of the ethmoid bone.

The present study was performed on axial and coronal CT scans of 212 patients. Scans were analyzed by an anatomist and a radiologist for the presence of Haller's cells, agger nasi cells, Onodi's cells and pneumatized crista galli. Results demonstrated the presence of Haller's cells in 21.2%, Onodi's cells in 10.4% and pneumatized crista galli in 2.4% of patients. A pneumatized anterior clinoid process was found in 0.5% of the patients. The data obtained in our study were compared with those reported in other anatomic and radiologic studies.

Adult↗