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PubMed1985

Three-dimensional distribution of neuromuscular junctions in human cricothyroid.

Microinjections of myoneural blocking agents are effective in the treatment of strabismus and have been proposed as a possible technique to treat spastic dysphonia. The success of such a technique would rely on a precise knowledge of the neuromuscular junction distribution in the laryngeal muscle to be injected. In view of the possibility of an involvement of the cricothyroid muscle in spastic dysphonia or other neuromuscular disorders, we determined the three-dimensional distribution of neuromuscular junctions in the human cricothyroid muscle. Cricothyroid muscles obtained from autopsy cases were fixed, sectioned, and processed for the histochemical localization of neuromuscular junction acetylcholinesterase. Using serial sections and a computer interfaced X-Y digitizer, the neuromuscular junctions were referenced to various anatomic landmarks and the neuromuscular junction distribution and reconstructed in three dimension using computer graphics.

Computers↗

PubMed1990

The ventral 'L' island flap. A refined model for skin flap research.

The rat has long been used as an experimental model for obtaining preliminary data in skin flap research. Unfortunately, there has been a great deal of inconsistency both in the experimental design of the skin flaps used in this animal model and in their inherent survival pattern. We have developed a ventral "L" flap based on clear anatomic landmarks that offers a number of advantages over previously described rat skin flaps including a more consistent survival pattern. This flap was elevated in 23 rats, resulting in an average necrosis of 16.7% +/- 7.6% 7 days postoperatively. Our article outlines the details of this flap's design and its use. The ventral L flap offers a refined tool for skin flap research in the rat animal model.

Animals↗

PubMed1991

The triple facelift. Current approach.

The combination of deep temporal facelift, subpalpebral facelift, and cervicofacial facelift constitutes the triple facelift. It exerts vertical traction with anchorage to solid anatomical landmarks, which permits perfect correction of ptosis. In addition, since this traction affects the upper two thirds of the face, the malar detachment of the cervicofacial facelift is considerably reduced or even nonexistent. Only the cervical phase is retained to reestablish the cervicomental angle. This technique, therefore, has the advantage of improving the quality of the result and reducing the postoperative course.

Facial Muscles↗

PubMed1996

Biomechanics of the helical rim advancement flap.

OBJECTIVES: To determine how helical rim closure with advancement flaps affects ear length and cupping, to compare the tension of closure with wedge excision and helical rim advancement and the effects of 3 tension-decreasing surgical techniques, and to review clinical experience with this flap. DESIGN: The laboratory study was performed on 6 fresh cadaver ears, by means of sequential excision of tissue, and closure tension was measured with a strain gauge. Results obtained in 10 patients were reviewed. SETTING: University referral hospital. PATIENTS: Ten patients with helical rim defects treated with helical rim advancement flaps. INTERVENTION: In cadaver ears, a helical rim defect of 5 mm was enlarged sequentially to 10 mm, 15 mm, and finally 20 mm. In the patients, defects of the helical rim caused by trauma or tumor were closed by this helical rim advancement flap method. MAIN OUTCOME MEASURES: For the laboratory study, the outcome measures were tension of closure of the defect, ear length, and ear cupping. For the review of cases, outcome was determination of perioperative complications and the patient's and surgeon's judgment of cosmetic appearance. RESULTS: Closure of a helical rim defect with advancement flaps caused minor shortening and moderate cupping of the ear. The tension of closure was decreased by extending the inferior incision into the earlobe, creating a Burow triangle, and shaving cartilage from the scapha. Both the Burow triangle and the scaphal shave caused mild increases in ear cupping. CONCLUSION: Helical rim advancement flaps provide satisfactory closure of helical rim defects up to at least 20 mm (longer in some ears) with excellent preservation of normal anatomic landmarks and a near-normal appearance of the reconstructed ear.

Adolescent↗

PubMed2001

Regional brain and ventricular volumes in Tourette syndrome.

BACKGROUND: The pathophysiology of Tourette syndrome (TS) is thought to involve disturbances in cortico-striato-thalamo-cortical circuitry. The morphological characteristics of the cortical and associated white matter portions of these circuits have not been previously examined in TS subjects. METHODS: High-resolution anatomical magnetic resonance images were acquired in 155 TS and 131 healthy children and adults. The cerebrums and ventricles were isolated and then parcellated into subregions using standard anatomical landmarks. RESULTS: For analyses that included both children and adults, TS subjects were found to have larger volumes in dorsal prefrontal regions, larger volumes in parieto-occipital regions, and smaller inferior occipital volumes. Significant inverse associations of cerebral volumes with age were seen in TS subjects that were not seen in healthy controls. Sex differences in the parieto-occipital regions of healthy subjects were diminished in the TS group. The age-related findings were most prominent in TS children, whereas the diminished sex differences were most prominent in TS adults. Group differences in regional ventricular volumes were less prominent than in the cerebrum. Regional cerebral volumes were significantly associated with the severity of tic symptoms in orbitofrontal, midtemporal, and parieto-occipital regions. CONCLUSIONS: Broadly distributed cortical systems are involved in the pathophysiology of TS. Developmental processes, sexual dimorphisms, and compensatory responses in these cortical regions may help to modulate the course and severity of tic symptoms.

Adolescent↗

PubMed2005

Inferior approach for the isolation of the left-middle hepatic veins in liver resections: a safe way.

BACKGROUND: Control of blood outflow from the liver has become mandatory to reduce back-bleeding and prevent air emboli in difficult liver resections when dealing with the hepatic veins. Selective control of the major hepatic veins rather than unselective vena cava clamping is preferable in most of these cases. Extrahepatic isolation of the left-middle hepatic veins has been considered for a long time to be a hazardous maneuver, and there is no general agreement about the technique that should be used. HYPOTHESIS: The purpose of this article is to describe a technique used by us for the isolation of the left-middle hepatic veins so that total or selective (hemihepatic) vascular exclusion of the liver can be performed without vena cava clamping. METHODS: The inferior approach is easily accomplished soon after the exposure of some anatomical landmarks, and a triangle is described in which a clamp is inserted or, alternatively, when one uses a superior approach, when the instrument tip exits to enable the veins' looping. CONCLUSION: Compared with other techniques, this approach is easier and safer to perform in nearly all cases, providing that there is no tumor located close to the vena cava or hepatic vein junction that contraindicates this maneuver.

Hepatectomy↗

PubMed1999

Distribution of the catecholaminergic neurons in the central nervous system of human embryos and fetuses.

The catecholaminergic cell groups in the human brain, denominated from A1 to A17, display some striking anatomical differences with those described in the rodent. These differences are essentially observed in the extent of the dopaminergic neurons and especially their axonal fields in the telencephalon. Immunocytochemistry for tyrosine-hydroxylase and dopamine-ss-hydroxylase allowed the visualization of the precocious human catecholaminergic groups as early as 4.5 postovulatory weeks. Maps of tyrosine-hydroxylase positive neurons generated in the different rhombomeres, midbrain, and prosomeres are shown following the prosomeric model introduced by Puelles and Rubenstein [(1993) Trends Neurosci. 16:472-476]. Such a description is convenient to compare catecholaminergic systems in different mammalian species and provide clear anatomical landmarks of the embryonic substantia nigra (midbrain and prosomeres 1 and 2), that are necessary for transplantation of neural tissue in Parkinson's disease. The development and early specification of the dopaminergic neurons expressing calbindin D28K phenotype in the substantia nigra and in the ventral tegmental area are described. The catecholaminergic axons enter the anlage of the cerebral cortex just after the formation of the cortical plate, from 7 postovulatory weeks on. They invade the subplate layer where they wait for 4 weeks before penetrating the cortical plate. At midgestation, the different areas and layers of the frontal cerebral wall are invaded by the catecholaminergic axons, before the layering of the cortex is completed, in a pattern of fiber distribution similar to that described in the adult human brain. The early pattern of development of the catecholamine systems appeared to be phylogenetically well preserved in mammals, but specific features emerging during the differentiation period are unique to humans.

Animals↗

PubMed1998

Development of an endoscopic navigation system based on digital image processing.

We developed a new system to couple the endoscope to an optical position measurement system (OPMS) so that the image frames from the endoscope camera can be labeled with the accurate endoscopic position. This OPMS is part of the EasyGuide Neuro navigation system, which is used for microsurgery and neuroendoscopy. Using standard camera calibration techniques and a newly developed system calibration, any 3-dimensional (3-D) world point can be mapped onto the view from the endoscope. In particular, we can display the coordinates of any anatomical landmark of the patient as it is viewed from the current position of the camera. This and other image-processing techniques are applied to the labeled frame sequence in order to offer the neurosurgeon a variety of control modules that increase the safety and flexibility of neuroendoscopic operations. Several modules, including a new motion alarm system and the "tracking" and "virtual map" modules, were tested in a human cadaveric model using the frontal and occipital approaches. A failure rate of 8.6% was experienced during testing of the first version of the software, but the second version was 100% successful. Thus, an endoscopic navigation system based on digital image processing has been developed that could be a revolutionary advance in image-guided surgery.

Cadaver↗

PubMed1998

Indications for computer-assisted surgery in otorhinolaryngology.

Indications for the use of computer-assisted surgery (CAS) in otorhinolaryngology can be grouped into several domains including the following: difficult cases involving the anterior, middle, and posterior skull base, especially the rhinobasis or laterobasis, and diseases of the petrous bone, the infratemporal fossa, the retromaxillar space, and the orbit; extended paranasal sinus surgery and revision cases with surgically altered anatomic landmarks; and use for educational purposes where CAS can provide better instruction in surgical anatomy by relating the surgical field to radiological sectional images. A new field for CAS is surgery of the inferior neck soft tissues or pathologic processes reaching into the upper mediastinum.

Humans↗

PubMed1996

Prenatal development of cranial base in normal Korean fetuses.

BACKGROUND: The cranial base is not only an end result of complex segmental growth of rostral end of axial skeleton but also has a tremendous impact on the development of the brain and facial structure. However, little is known about the method for the systematic analysis of the shape of the cranial base in the developing human fetus. We used roentgenograms of the cranial base and eviscerated bones for the assessment of the development of the cranial bony complex. METHODS: The cranial base was removed from 64 normal human fetuses after 18-40 weeks of gestation. Roentgenograms were taken perpendicular to the cranial base. Major anatomical landmarks are defined as follows: the center of pituitary fossa of sphenoid bone (point S), the growth center of zygomatic bone, the anterior point of nasal septum, otic cartilage, and anterior and posterior growth centers of maxilla. The anterior cranial base angle, the middle cranial base angle, the posterior cranial base angle, the maxillary trapezoid area, the horizontal middle face area, and the occipital cranial base triangle area are defined from the landmarks, and the growth of each parameter was analyzed by gestational age. RESULTS: The proportional growth of the anterior, middle, and posterior cranial fossae could be assessed by the angles around the center of the pituitary fossa (point S) and by the anterior, middle, and posterior cranial base angles. The anterior cranial base angle was relatively constant during the fetal period at 107.4-112.5 degrees, whereas the middle cranial base angle gradually increased, and the posterior cranial base angle decreased. With increasing gestational age, the horizontal middle face area increased rapidly, in contrast to those of the maxillary trapezoid area, occipital cranial base triangle area, or foramen magnum area. CONCLUSIONS: The important keys in the structural development of the normal human cranial base are anterior, middle, and posterior cranial base angles. We could define the developmental pattern of human cranial base, which in turn provides a model of a standard growth pattern applicable to the study of the different malformations in the craniofacial structure.

Cephalometry↗

PubMed1996

Large electrodes improve nerve conduction repeatability in controls as well as in patients with diabetic neuropathy.

Recording site is an important cause of variability of compound muscle action potential (CMAP) and conduction parameters, which can be reduced by using large electrodes. Repeatability of CMAP and conduction parameters of conventional and large electrodes was compared in 16 controls and 17 diabetic neuropathic patients, using defined recording sites linked to anatomical landmarks. Right-sided median, peroneal, and tibial nerves were investigated twice with a 1-2 week interval by the same examiner. Compared to previous studies, conventional electrodes on strictly defined recording sites resulted in better repeatability: intraindividual coefficients of variation (CV) varied between 4% and 14.4% for all parameters. CV of conduction parameters, not published previously, was smaller than CV of CMAP parameters. The use of large electrodes improved repeatability further: large electrodes resulted in substantially smaller CV for duration, amplitude, area, and changes of amplitude and area over a length of nerve, which were reduced by 10%, 31%, 29%, 27%, and 16%, respectively. Patients had higher CV than controls; large electrodes reduced patient CV more than control CV, resulting in less contrast between groups. Strictly defined recording sites and large electrodes improve repeatability of motor conduction studies to relevant degrees: all CMAP and conduction parameters are suitable for longitudinal studies of neuropathic patients.

Action Potentials↗

PubMed1998

The effects of muscular dystrophy on craniofacial growth in mice: a study of heterochrony and ontogenetic allometry.

Mechanical loading of muscles on bones at their sites of attachment can regulate skeletal morphology. The present study examined the effects of muscle degeneration on craniofacial growth, using two strains of muscular dystrophic mice, Mus musculus, differing in pathological severity. We collected radiographic and weight data longitudinally and digitized radiographs to obtain distances between anatomical landmarks in different functional regions of the skull. We then quantified heterochronic and allometric differences among genotypes and between sexes. Because growth is nonlinear with respect to time, we first used the Gompertz model to obtain heterochronic growth parameters, which were then tested with ANOVA. Ontogenetic allometric analyses examined the scaling relationships between various measurements with linear regressions. For most measurements the severely dystrophic mice are significantly smaller in final size than both the control and the mildly dystrophic mice, which are statistically indistinguishable. Measures of total growth and the neurocranium exhibit more differences among groups in heterochronic parameters of early ontogeny because growth in these regions is controlled primarily by brain expansion that ceases early in development. In contrast, the face and mandible exhibit more differences in later growth parameters possibly because of the increased influence of muscles on these regions as growth progresses. The severely dystrophic mice have flatter, more elongate skulls and mandibles than those of the other two genotypes, concurrent with an absence of muscular forces to stimulate growth in a superior-inferior direction.

Alleles↗

PubMed1997

Warping CT scans from nontreatment to treatment position.

This paper describes a cost-effective technique that optimally utilizes all available diagnostic studies for three-dimensional treatment planning. A simulator unit modified to produce cross-sectional images (simulator-CT unit) is used to create a reference data set with the patient in the treatment position. Registration software (qsh) brings other diagnostic studies into agreement with this reference data set. Two cases are presented as examples of the use of this technique. Registration of abdominal scans from the same patient demonstrates the warping of a nontreatment position study to the treatment position. The second case is based on paired data sets through the head, in which the diagnostic study was obtained by using a gantry tilt to follow the base of the skull and to avoid sections passing through the teeth. The registration software provides a method for combining diagnostic studies into a single "master" data set. The success of the transformation depends on the operator's ability to identify corresponding anatomic landmarks for different data sets and on the magnitude of the variation in the patient's position from one procedure to the next. Limitations in image quality and the number of cross-sections obtainable from a simulator-CT unit can be partially overcome by using the described technique. Thus, the information contained in nontreatment position diagnostic tests can be used accurately for treatment planning at limited cost.

Anatomy, Cross-Sectional↗

PubMed1999

Snare-assisted vascular access: a new technique.

Access to the central circulation can be difficult in small infants, particularly when normal anatomic landmarks have been altered. We describe a new technique that utilizes any existing central catheter to establish additional sites of vascular access. A 4 Fr end hole catheter is advanced under fluoroscopic guidance to the desired site of new vascular access. A 10-mm Amplatz snare catheter is advanced through the end hole catheter and the loop opened within the target vessel lumen. The snare is then used to guide percutaneous placement of a Cope wire through a 21-gauge needle and then to pull the wire into the central circulation. New access is then achieved by introducing an additional catheter over the guidewire. This technique has now been successfully utilized 16 times in 13 patients. Snare assistance is a safe and effective technique that provides a reliable means of establishing additional secure vascular access. Cathet. Cardiovasc. Intervent. 47:315-318, 1999.

Catheterization↗

PubMed2000

Evaluating the function of hippocampal subregions with high-resolution MRI in Alzheimer's disease and aging.

Memory ability declines in older age groups. There is a growing list of physiological processes that target the hippocampal formation in an age-related fashion, and some might underlie the hippocampal component of memory decline. The hippocampal formation is comprised of separate subregions, and physiological processes differentially target these subregions. The ability to evaluate the functional integrity of individual subregions-performing subregional analysis-is a major clinical goal since it can aid in the diagnosis of memory decline, as well as in elucidating mechanisms of disease and testing potential interventions. Because of its superior spatial resolution, magnetic resonance imaging (MRI) is best suited to accomplish this goal. Despite limited success, most functional MRI (fMRI) protocols have difficulty in performing complete subregional analysis of the hippocampal formation. Here we address sources of difficulty by (1) generating T2* -weighted maps of the hippocampal formation with sub-millimeter resolution; and (2) by adapting an approach used by animal investigators to identify the hippocampal subregions using anatomical landmarks. The protocol is tested in patients with Alzheimer's disease and in healthy controls, in an effort to determine whether it can detect neuronal dysfunction. Results showed diminished signal in the hippocampal formation of patients with Alzheimer's disease (AD) compared to controls, and multivariate analysis showed that this difference was most prominent in the entorhinal cortex. The protocol can be used to perform subregional analysis of the hippocampal formation. Testing the protocol in other clinical populations is needed to demonstrate its efficacy in evaluating the neuronal integrity of all hippocampal subregions.

Aged↗

PubMed2000

Computer-assisted fluoroscopy-based reduction of femoral fractures and antetorsion correction.

OBJECTIVE: Intra-operative fluoroscopy is a valuable tool for visualizing underlying bone, implant, and surgical tool positions in orthopedics. It has brought about the minimally invasive surgical technique of intramedullar nailing to fix femoral shaft fractures. However, the limited field of view and two-dimensional property of fluoroscopic images aggravate intra-operative control of surgical parameters. The purpose of this article is to introduce a surgical navigation system based on fluoroscopy that provides missing information for the procedure of femoral fracture fixation. MATERIALS AND METHODS: Optoelectronic markers are placed on a surgical drill, involved bone fragments, the femoral nail, and the fluoroscope to track their positions. Projection properties of the fluoroscope are acquired through an initial precalibration. The relative positions of bone fragments, implants, and surgical tools are displayed superimposed simultaneously and in real time on multi-planar intra-operative fluoroscopic images. This is achieved by computer simulation of X-ray projections that have taken place with acquisition of the fluoroscopic images. In addition, a method has been developed that allows contactless measurement of three-dimensional anatomic landmarks, based on their representation in fluoroscopic images. In combination with optoelectronic tracking, this enables dynamic calculation of important surgical parameters such as femoral antetorsion. RESULTS: A pilot surgery showed that fracture reduction can benefit from the developed computer-assisted method. An in-vitro study on computer-assisted measurement of femoral antetorsion demonstrated the high degree of precision of this technique.

Bone Nails↗

PubMed2000

Intra-operative tracking of the trunk during surgical correction of scoliosis: a feasibility study.

OBJECTIVE: The purpose of this study was to evaluate the feasibility of a technique for intra-operative tracking of the trunk during scoliosis surgery. MATERIALS AND METHODS: Eleven magnetic sensors placed on specific anatomical landmarks are used to compute 11 geometric indices of the trunk. This technique was assessed on a cohort of 40 subjects (19 normal, 21 scoliotic) using an experimental set-up simulating the position of patients during scoliosis surgery. RESULTS: The indices varied less than 2 mm and 1 degrees when breathing (except for chest AP diameter), and less than 1 mm and 1 degrees after transient displacement from the initial positioning of the subjects. No significant changes were observed for most of the indices between two acquisition sessions. Comparison between normal and scoliotic subjects demonstrated that the trunk geometry is more influenced by the positioning of each subject on the operating table than by the magnitude of the spinal deformity. CONCLUSION: The proposed technique will allow intra-operative tracking of the trunk and enable the surgeon to optimize the correction of both spinal and trunk deformities. The technique can also be used to evaluate the adequacy of patient positioning on the operating table, and to obtain a complete follow-up of patients in pre-, intra-, and post-surgical conditions.

Adolescent↗

PubMed2001

Expanding the boundaries of the transsphenoidal approach: a microanatomic study.

The anatomic features of a transsphenoidal approach are reviewed, focusing on the microsurgical anatomy of parasellar structures. Pertinent microsurgical anatomy is described in sufficient detail for the neurosurgeon to successfully extend a standard transsphenoidal approach for treatment of lesions involving the region of the tuberculum sellae, planum sphenoidale, supradiaphragmatic intradural space, and medial cavernous sinus. The parasellar region of 50 formalin-fixed cadaveric heads was examined by using magnification 3x to 40x. The arterial and venous systems of five cadaveric specimens were injected under pressure with colored silicone rubber. The sellar region of three specimens was examined histologically. Important anatomic landmarks identified in the roof of the sphenoid sinus include a carotid and trigeminal prominence, as well as a tubercular, clival, and opticocarotid recess. The diaphragma sella is actually comprised of two layers of dura, with a venous system (circular sinus) interposed between the layers. The dura mater of the pituitary gland separates the gland from the medial compartment of the cavernous sinus. The microanatomic detail necessary to extend the transsphenoidal approach to the supradiaphragmatic intradural space and medial compartment of the cavernous sinus is described. These data are presented to facilitate the clinical application of these extended approaches.

Cadaver↗