[The extremely lateral lumbar disk hernia: results of a lateral approach].
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Adult↗
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[Lateral intervertebral disk displacement: analysis of a series with lateral and paramedian surgical approach].
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Adult↗
What is your diagnosis? Lateral condylar fracture of the tibial plateau, comminuted supracondylar and lateral condylar femoral fractures, fractured public bone, and craniodorsal coxofemoral luxation.
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Accidents, Traffic↗
Normal and transplanted lateral knee menisci: evaluation of extrusion using magnetic resonance imaging and ultrasound.
The aim of the study is to develop a clinically useful and reproducible method for evaluating lateral meniscal extrusion in normal and transplanted knees under different axial loading conditions. Magnetic resonance imaging (MRI) and ultrasound (US) were used to assess meniscal extrusion. Both types of imaging were performed at least 6 months postoperatively (mean 23.5 months). Coronal MR images (DESS-3D sequence) of the lateral compartments of 10 normal knees and 17 transplanted lateral knees were analyzed. Extrusion was defined as the distance measured from the femoral condyle or tibial plateau to the outer edge of the meniscus. Subjects were examined in the supine position. Ultrasound print-outs of the lateral compartment of both knees of ten patients (transplanted side and contralateral normal side) were analyzed. Extrusion cross-sectional area (CSA) and distance were measured just anterior to the lateral collateral ligament: the former was defined as the CSA of the meniscus outside the knee, the latter as the greatest distance from a line connecting the femur and tibia to the outer edge of the lateral meniscus. Patients were examined in the supine position, bipodal stance and unipodal stance. The viable meniscal allograft was securely sutured to a bleeding functional meniscal rim. No bone blocks were used to fix the allograft; instead, the anterior and posterior horn were firmly sutured to their enthesis. The MRI results (tibial) show the transplanted lateral meniscus to be significantly (p<0.005) more extruded in comparison to the normal lateral meniscus. The anterior horn (mean 5.8 mm, SD=2.8) of the transplanted lateral meniscus tends to be more extruded than the posterior horn (mean 2.7 mm, SD=1.48). The posterior horn of the normal lateral meniscus does not (mean 0 mm) extrude, while the mean extrusion of the anterior horn is 0.8 mm (SD=0.92). In the US results, the transplanted lateral meniscus is significantly (p<0.005) more extruded than the normal lateral meniscus in all patient positions. Both cross-sectional surface and distance are equally good parameters to determine meniscal extrusion. There is no statistical difference between patient positions. The transplanted lateral meniscus extrudes, in the supine position, bipodal and unipodal stance 6.43 (SD=1.84), 6.01 (SD=1.93) and 6.99 mm (SD=2.7) respectively. The extrusion surface of the lateral transplanted meniscus is 50.50 mm2 (SD=15.32), 47.24 mm2 (SD=14.35) and 58.61 mm2 (SD=29.65) in the supine position, bipodal stance and unipodal stance respectively. The normal lateral meniscus extrudes in the supine position, bipodal and unipodal stance 3.77 (SD=1.76), 3.94 (SD=1.66) and 3.79 mm (SD=1.79) respectively. The extrusion surface of the normal lateral meniscus is 22.42 mm2 (SD=12.54), 23.24 mm2 (SD=12.74) and 24.79 mm2 (SD=10.18) in the supine position, bipodal stance and unipodal stance respectively. The presented data shows that the transplanted lateral meniscus, without bone block fixation but with firm fixation of the horns to the original entheses, extrudes in the lateral direction significantly more than the normal meniscus. The transplanted lateral meniscus, however, does not extrude more in the lateral direction under axial load. The anterior horn of both normal and transplanted menisci is extruded more laterally than the posterior horn. Both methods are adequate to measure laterally-directed extrusion of the normal and transplanted lateral meniscus, but have distinctive advantages and disadvantages: MRI in this series visualizes the complete-from posterior to anterior-meniscal body, but only in the supine, non-weight-bearing position. Using ultrasound one can evaluate the meniscal extrusion in different conditions of axial loading, but only from a single examination point.
Adolescent↗
Organization of the primary projections of the lateral line nerves in the lamprey Lampetra japonica.
The lateral line sensory system of Lampetra japonica is innervated by the anterior and posterior lateral line nerves. The anterior lateral line nerve innervates all electroreceptors throughout the body and mechanoreceptors of the head. The posterior lateral line nerve innervates trunk mechanoreceptors. The anterior lateral line nerve consists of two ganglia (anterior lateral line and intracapsular) and four major peripheral branches (superficial ophthalmic, buccal, hyomandibular, and recurrent nerves). The posterior lateral line nerve has one posterior lateral line ganglion and one peripheral branch. The location and central projection patterns of the primary sensory neurons of these branches of the lateral line nerves were studied with the aid of horseradish peroxidase labeling. The ganglion cells of the buccal nerve were found in the rostral half, and those of the hyomandibular nerve were found in the caudal half of the medial part of the anterior lateral line ganglion. The lateral part of the anterior lateral line ganglion contains ganglion cells of the recurrent nerve and the superficial ophthalmic nerve. The rostral half of the intracapsular ganglion contains ganglion cells of the recurrent, hyomandibular, and buccal nerves. The ganglion cells of the posterior lateral line nerve were found in the posterior lateral line ganglion. The buccal nerve afferents terminated mainly in the lateral part of the ipsilateral mechanoreceptive medial nucleus. The peripheral part of the electroreceptive dorsal nucleus also received several afferents. The hyomandibular afferents terminated ipsilaterally in the central part of the medial nucleus and in the dorsolateral part of the dorsal nucleus. Some afferents of the hyomandibular nerve ascended and descended in the descending nucleus of the trigeminal nerve near its dorsal margin. The ventral nucleus, the primary nucleus of the VIIIth nerve, received a few fibers of the buccal and hyomandibular nerves. In the recurrent nerve, the fibers of the lateral part of the anterior lateral line ganglion terminated throughout the entire dorsal nucleus, and the fibers of the intracapsular ganglion projected to the dorsolateral part of the nucleus. The afferents of the posterior lateral line nerve terminated in the medial part of the ipsilateral medial nucleus and in the lateral part of the contralateral medial nucleus. In the cerebellar area, afferents of the anterior lateral line nerve were located laterally to those of the posterior lateral line nerve. Several fibers terminated in some branchiomotor nuclei, the cerebellar crest, and the dorsal gray near the obex level. No efferent cell bodies were found in the place where efferent neurons of the VIIIth nerve have been previously reported.
Afferent Pathways↗
Peripheral and central aspects of the acoustic and lateral line system of a bottom dwelling catfish, Ancistrus sp.
The topographical relationship between the swim bladder, the inner ear, and the otic lateral line was studied in the bottom dwelling catfish, Ancistrus sp. In addition, afferent and efferent subcomponents of the eighth and lateral line nerves were labelled with horseradish peroxidase (HRP) or with differently fluorescing dextran amines. The swim bladder of Ancistrus consists of two separate, transversely oriented parts of each of which is connected to the sinus impar of the inner ears via two Weberian ossicles and the perilymphatic sac. The osseous capsula of the ear has two foramina other than the nerve foramina. One is for the sinus impar. The other foramen, which also separates two fluid-filled spaces, exits where the horizontal canal of the ear contacts the otic lateral line. Both the otic and the postotic lateral line canal run deep below the epidermis. Each canal contains a neuromast that is innervated by the middle lateral line nerve. Further caudally, the otic lateral line canal gives rise to the postotic and finally to the truck canal whose nonossified anterior part travels through an ossified chamber that surrounds the swim bladder. Thus the anterior part of each trunk lateral line canal is in contact with a bipartite sound pressure receiver, the swim bladder. Anterior and posterior lateral line afferents terminate ipsilaterally throughout the neuropil of the electroreceptive lateral line nucleus and the mechanoreceptive nuclei medialis and caudalis of the medulla. Middle lateral line afferents terminate between the projection sites of anterior and posterior lateral line afferents. Some primary mechanosensory anterior lateral line nerve fibers continue into the ipsilateral eminentia granularis and the valvula cerebelli. In the electroreceptive lateral line projection, anterior lateral line fibers terminate more medially and posterior fibers more laterally. This somatotopy is not as clear-cut in the mechanosensory lateral line. Afferents of the sacculus and the lagena terminate predominantly in the saccular nucleus. Afferents of the utriculus, the horizontal canal, and the anterior vertical canal terminate in the magnocellular vestibular nucleus and in the medial octavolateral nucleus. The projection sites of the anterior part and the posterior part of the eighth nerve show little overlap. Eighth nerve projections to the valvula cerebelli are less prominent than the projections from the lateral line. Eighth nerve and lateral line nerve efferents arise from a common nucleus, the octavolateralis efferent nucleus. Axons of efferent cells may divide to supply two or more branches of the eighth nerve and some axons supply both lateral line and eighth nerve endorgans.(ABSTRACT TRUNCATED AT 400 WORDS)
Afferent Pathways↗
Anatomy of the lateral canthal tendon.
OBJECTIVE: The purpose of this study was to clarify and describe the anatomy of the lateral canthal tendon. Knowledge of this anatomy is essential in selection of appropriate surgical procedures to restore orbital anatomy. STUDY DESIGN: Gross dissections were performed of the lateral orbital soft tissues from 21 preserved Caucasian cadaveric orbits. A block of the bony attachment of each lateral canthus was taken for histologic examination. After anatomical exposure, the following measurements of the lateral canthus were made: (1) the distance from the midpoint of insertion of the lateral canthus at the lateral orbit to the zygomaticofrontal suture; (2) the horizontal width of the lateral canthus, as measured from the lateral commissure to the lateral orbit; (3) the vertical difference in height between the medial canthal and lateral canthal insertions. RESULTS: The mean midpoint of the lateral canthus insertion was 10. 24 mm inferior to the zygomaticofrontal suture (range, 5-15 mm). The mean horizontal length of the lateral canthus from the lateral commissure to the lateral orbit was 7.52 mm (range, 2-12 mm). The mean vertical difference in height between the insertions of the medial canthus and the lateral canthus was 1.35 mm (range, -2-4 mm), the lateral canthus being at a more superior point. Histologic examination of hematoxylin-eosin-stained slides showed that the fibers of the lateral canthus inserted into the periosteum but not beyond it. CONCLUSIONS: The lateral canthal tendon attaches the upper and lower tarsal plates to Whitnall's tubercle inside the orbital rim deep to the septum. A precise knowledge of the periorbital anatomy will assist the surgeon in the selection of appropriate surgical techniques that will provide for restoration of this delicate anatomical configuration.
Eyelids↗
The location of the vertebral artery foramen and its relation to posterior lateral mass screw fixation.
STUDY DESIGN: This study evaluated the anatomic relationship between the vertebral artery foramen and the posterior midpoint of the cervical lateral mass using cervical spine specimens. OBJECTIVES: To determine quantitatively the location of the vertebral artery foramens from C3 to C6 and their relationship to the posterior midpoints of the lateral masses. SUMMARY OF BACKGROUND DATA: Anatomic studies of the cervical nerve root and facet relative to lateral mass screw placement have been addressed. It is necessary to know the correct location of the vertebral artery foramen during lateral mass screw placement to minimize the risk of injury to the vertebral artery. METHODS: Forty-three cervical spines from C3 to C6 were directly evaluated for this study. Anatomic evaluation included the dimension of the vertebral artery foramen and its projection on the posterior aspect of the lateral mass. The vertical distance from the posterior midpoint of the lateral mass to the posterior border of the vertebral artery foramen, and the angle between the parasagittal plane and the line connecting the posterior midpoint of the lateral mass with the lateral limit of the vertebral artery foramen, were also measured. RESULTS: The vertical distances from the posterior midpoint of the lateral mass to the vertebral artery foramens at C3-C6 averaged from 9.3 to 12.2 mm for male and female specimens. The average angles medial to the sagittal plane, between the parasagittal plane and the line connecting the posterior midpoint of the lateral mass with the lateral limit of the vertebral artery foramen, from C3 to C5, were found to range from 6.0 degrees to 6.3 degrees for male specimens and from 5.3 degrees to 5.5 degrees for female specimens. At C6, the average angles lateral to the sagittal plane, between the parasagittal plane and the line connecting the posterior midpoint of the lateral mass with the lateral limit of the vertebral artery foramen, were 6.4 degrees for male specimens and 5.4 degrees for female specimens. CONCLUSIONS: The present study indicated that there is no risk of damaging the vertebral artery if a screw is directed perpendicular to the posterior aspect of the lateral mass at C3-C5 and 10 degrees lateral to the sagittal plane at C6 starting at the midpoint of the lateral mass.
Adult↗
Posterior screw placement on the lateral mass of atlas: an anatomic study.
STUDY DESIGN: An anatomic study evaluating the feasibility of posterior screw fixation on the lateral mass of the atlas and comparing the pullout force of C1 posterior lateral mass screws with that of occipital and C2 pedicle screws. OBJECTIVES: To study the feasibility, anatomy, and biomechanics of posterior screw fixation within the lateral mass of the atlas. SUMMARY OF BACKGROUND DATA: Occipitocervical fusion is a common choice for atlantoaxial dislocations. After that the movement of occipitocervical region will be restricted. If screws could be placed in the lateral mass of the atlas, 1) the movement of C0-C1 junction will be preserved; 2) through the screw the dislocated atlas could be pulled backward; and 3) the fractured lateral mass can be fixed using the posterior lateral mass screw directly. METHODS: Thirty atlas specimens of native adults were used to measure pertinent clinical data. Six fresh upper cervical specimens were used to observe the association of the C2 nerve and the lateral mass of the atlas. The pullout force of the C1 lateral mass was measured and compared with that of screws placed into the occiput and C2 pedicle, respectively. RESULTS: The distances from the midline to the midpoint of the C1 lateral mass, to the inner wall of the transverse foramen, and to the inner edge of the pedicle were 17.6 +/- 1.2 mm, 23.0 +/- 1.7 mm, and 14.2 +/-1.1 mm, respectively. The width and height of the C1 lateral mass were 11.6 +/- 1.4 mm and 12.7 +/- 1.0 mm, respectively. The distance between the inferior midpoint of the C1 lateral mass in the transverse plane of the midposterior arch of the atlas to the edge of the inferior atlas joint line was 4.1 +/- 0.7 mm. The width of the posterior arch at the point of vertebral artery overpass was 4.7 +/- 1.0 mm. The observation on the fresh specimens showed that the C2 nerve passes inferolateral to the C1-C2 joint and could be pulled sideways. The screw pullout force within the lateral mass of the atlas was 1818.16 +/- 422.67 N. This is significantly less than that of screws within the occiput, and there was no difference with that of a C2 pedicle screw. CONCLUSION: The width and height of the atlas lateral mass were larger than that of the C2 pedicle, and there was enough space to insert a 3.5-mm diameter screw in the atlas lateral mass over the C2 nerve. The pullout force of the screw on the lateral mass of the atlas was the same as that of the C2 pedicle screw. It is possible toinsert a 3.5-mm screw in the lateral mass of the atlas. The direction of the screw should be about 20 degrees anterosuperior in the vertical plane and 15 degrees inward in the horizontal plane. The suitable length of the screw should be approximately 22 mm inside the lateral mass.
Anthropometry↗
Dorsal thalamic connections of the ventral lateral geniculate nucleus of rats.
In order to understand better the organisation of the ventral lateral geniculate nucleus of the ventral thalamus, this paper has examined the patterns of connections that this nucleus has with various nuclei of the dorsal thalamus in rats. Injections of biotinylated dextran or cholera toxin subunit B were made into the parafascicular, central lateral, posterior thalamic, medial dorsal, lateral dorsal, lateral posterior, dorsal lateral geniculate, anterior, ventral lateral, ventrobasal and medial geniculate nuclei of Sprague-Dawley rats and their brains were processed using standard tracer detection methods. Three general patterns of ventral lateral geniculate connectivity were seen. First, the parafascicular, central lateral, medial dorsal, posterior thalamic and lateral dorsal nuclei had heavy connections with the parvocellular (internal) lamina of the ventral lateral geniculate nucleus. This geniculate lamina has been shown previously to receive heavy inputs from many functionally diverse brainstem nuclei. Second, the visually related dorsal lateral geniculate and lateral posterior nuclei had heavy connections with the magnocellular (external) lamina of the ventral lateral geniculate nucleus. This geniculate lamina has been shown by previous studies to receive heavy inputs from the visual cortex and the retina. Finally, the anterior, ventral lateral, ventrobasal and medial geniculate nuclei had very sparse, if any, connections with the ventral lateral geniculate nucleus. Overall, our results strengthen the notion that one can package the ventral lateral geniculate nucleus into distinct visual (magnocellular) and non-visual (parvocellular) components.
Animals↗
Extended upper blepharoplasty for lateral hooding of the upper eyelid using a scalpel-shaped excision: a 13-year experience.
Excess skin of the upper lids is often accompanied by lateral overlap of skin with crow's feet because of the absence of fixation to the tarsal plate, giving the eye a sad, heavy look that often disturbs the lateral visual field. The accepted crescent-shaped blepharoplasty is somewhat convex, which is widest at the center of the lid with or without a lateral extension. However, in patients who have normal brow position or minimal eyebrow ptosis and whose main concern is the excess upper eyelid skin and lateral hooding, such a crescent excision may not suffice. A scalpel-shaped excision that is widest laterally and that tapers to a point medially will extirpate the maximal skin where it is most needed and overcome the skin excess in the lateral aspect of the upper lid. Between 1990 and 2002, 301 white patients (275 women and 26 men) between the ages of 33 and 79 years were operated on using the extended scalpel-shaped upper blepharoplasty technique. The follow-up period was more than 1 year. The lower margin of the incision is along the supratarsal crease, about 10 mm above the ciliary line. It begins medially about 1 cm above and lateral to the medial canthus. Above the lateral canthus, the skin marking is gently curved upward and outward, often within a natural skin crease or crow's feet to reach a little below and slightly beyond the lateral extremity of the eyebrow. The upper border of the incision joins the two extremities of the skin outline in a gentle convex curve. The general outline of the incision takes on the shape of a number 20 scalpel blade in which the maximal width is located laterally. Following excision of the excess skin and removal of protuberant fat pads if needed, suturing is executed from lateral to medial. The final suture line is in the form of an oblique flattened lazy S. Following the removal of the stitches on the fifth postoperative day, no wound dehiscence was noticed at the lateral scar zone. In the older individuals, due to the lax skin, the scar becomes scarcely noticeable with time and often falls within a pre-existent crow's feet crease. Elimination of some of the crow's feet was also demonstrated. In patients with visual field impairment, significant functional and visual improvement was achieved. Most patients mentioned a pleasing postoperative open "Oriental" look of the eyes. The extended scalpel-shaped upper blepharoplasty adequately deals with the hooding of the skin laterally. This technique overcomes the excess of skin in both vertical and horizontal directions, since in suturing the lateral part of the skin defect in an oblique plane, slack skin is taken up transversely, and the technique provides some indirect upward support to the lateral eyebrow. In the absence of crow's feet in the younger person, this technique is not recommended because the lateral part of this suture line is visible, especially if the scar widens.
Adult↗
Peripheral distribution and central projections of the lateral-line nerves in goldfish, Carassius auratus.
The lateral-line system of the goldfish, Carassius auratus, is described from the receptor distribution on the body surface to the termination of the primary afferents within the octavolateralis column. Goldfish have a continuous lateral-line canal system which consists of supraorbital, infraorbital, operculomandibular and supratemporal commissural canals on the head and a trunk canal extending the length of the trunk. There is a single neuromast between each 2 canal pores. The total number of canal neuromasts on the head ranges from 74 to 100. On the body the total number of canal neuromasts ranges from 52 to 60. Associated with each canal are populations of superficial neuromasts. There are approximately 1,000 superficial neuromasts on the head which are arranged in clusters or rows oriented perpendicular to the long axis of the associated canal. On the body there are 3-9 superficial neuromasts on each scale. Further, there is a total of 1,000 superficial neuromasts arranged in horizontal lines between the fin rays of the caudal fin. The neuromasts are innervated by branches of four lateral-line nerves. The dorsal anterior lateral-line nerve innervates the supraorbital and infraorbital canals and associated superficial neuromasts. The ventral anterior lateral-line nerve innervates the operculomandibular canal and associated superficial neuromasts, as well as superficial neuromasts on the operculum. The middle lateral-line nerve innervates the postotic canal and a cluster of associated superficial neuromasts. The posterior lateral-line nerve innervates the supratemporal commissural canal and associated superficial neuromasts, as well as the canal and superficial neuromasts on the trunk and caudal fin. Application of horseradish peroxidase to the individual branches of the lateral-line nerves shows that the posterior lateral-line nerve projects to the dorsal portion of the medial and caudal nuclei, whereas the anterior lateral-line branches project to the ventral portion. Lateral-line projections to the magnocellular and descending nuclei of the octaval column were also observed. The projections to the eminentia granularis are also segregated such that the anterior lateral-line nerves project to the anterolateral portion and the posterior lateral-line nerve to the caudal portion. Thus, there appears to be a topographic organization of the lateral-line projections to the lateralis column and eminentia granularis. However, this topography does not appear to be precise as the projections of the branches of the anterior lateral-line nerves overlap extensively, as do the branches of the posterior lateral-line nerves.
Afferent Pathways↗
[An anatomical study on lateral ligaments of rectum].
OBJECTIVE: To identify the location and contents of the rectal lateral ligaments and its relationship with the middle rectal artery and pelvic plexus. METHODS: Twenty-nine pelvics of human cadavers were sagittally sectioned into 58 hemipelvic specimens. All of hemipelvics were dissected with sharp technique under direct vision by one surgeon. The lateral ligaments were identified and the distances from the center of its pelvic attachment to sacral promontory and coccyx were measured. Then, the lateral ligaments were transected for histologic examination. RESULTS: Lateral ligaments of rectum were found in all 58 hemipelvics. The lateral ligaments connected the posterolateral aspect of the middle 1/3 of the rectum and mesorectum to the lateral aspect of the bodies of the second, third and fourth sacral vertebrae. The distance from the lateral ligament to sacral promontory was (8.3 +/- 1.6) cm on the right side and (8.4 +/- 1.4) cm on left side. The width of lateral ligaments was (3.2 +/- 0.4) cm on the right side and (3.1 +/- 0.4) cm on the left side. The distances from lateral ligament to the coccyx on the right and left sides were (5.2 +/- 1.4) cm and (5.0 +/- 1.3) cm respectively. The content of the lateral ligaments consisted of loose connective tissue with clusters of small nerves and blood vessels. Middle rectal artery was found in 83% (48/58) of hemipelvics and 47% (27/58) of the middle rectal artery went through the lateral ligaments. The inferior hypogastric nerve plexuses were formed inside the lateral ligament, and separated the ligament into two parts. The lateral segment of the lateral ligament contained the tributaries of internal iliac artery, and the medial segment contained nerve fibers or branches to the rectum, together with the middle rectal artery. CONCLUSION: The lateral ligaments of rectum are located on the posterolateral side of the rectum, much closer to the coccyx than to the sacral promontory, consisting of connective tissue containing multiple small nerves and middle rectal artery. The lateral ligament is a pathway of blood vessels and nerve fibers toward the rectum and lymphatic vessels from the lower rectum toward the iliac lymph nodes.
Adult↗
Medial amygdaloid suppression of predatory attack behavior in the cat: II. Role of a GABAergic pathway from the medial to the lateral hypothalamus.
The medial amygdala is known to powerfully suppress predatory attack behavior elicited by electrical stimulation of the lateral hypothalamus of the cat. In the preceding paper, it was shown that the initial limb of a pathway subserving suppression of predatory attack from the medial amygdala to the lateral hypothalamus projects to the ventromedial hypothalamus and its functions are mediated by substance P. The present study tested the hypothesis that the second limb of the pathway subserving medial amygdaloid suppression of predatory attack behavior projects from the medial to lateral hypothalamus and its functions are mediated by GABA. Cannula electrodes were implanted into the lateral hypothalamus for elicitation of predatory attack behavior as well as for the microinfusion of GABA compounds. Monopolar stimulating electrodes were implanted into sites within the medial amygdala from which subseizure levels of stimulation could suppress predatory attack behavior. Initially, the effects of dual stimulation of the medial amygdala and lateral hypothalamus upon response latencies for predatory attack were compared with single stimulation of the lateral hypothalamus alone. Dual stimulation was shown to significantly suppress predatory attack elicited from the lateral hypothalamus. Then, the GABAA receptor antagonist, bicuculline, was microinjected into sites within the lateral hypothalamus from which predatory attack was elicited in doses of 0.015, 0.075 and 0.15 nmol and paired trials of single and dual stimulation were again repeated in a manner identical to that applied prior to drug administration. Drug infusion produced a blockade of medial amygdaloid suppression of predatory attack in a time- and dose-dependent manner. Conversely, microinfusions of the GABAA receptor agonist, muscimol (10, 25 and 50 pmol), into the same lateral hypothalamic 'attack' site in the absence of medial amygdaloid stimulation suppressed predatory attack, thus simulating the effects of medial amygdaloid stimulation. Furthermore, pretreatment with bicuculline microinjected into the lateral hypothalamus blocked the suppressive effects of substance P, that was infused into the ventromedial hypothalamus, upon predatory attack. Receptor autoradiography demonstrated the presence of high affinity binding for GABAA receptors in the lateral hypothalamus. A combination of immunocytochemical and retrograde axonal tract tracing procedures, in which Fluoro-Gold was microinjected into the lateral hypothalamic attack sites, revealed the presence of populations of neurons labeled for both Fluoro-Gold and GABA in the ventromedial hypothalamus. These findings provide new evidence for the existence of a pathway from the medial to lateral hypothalamus whose functions are mediated by GABA. Thus, the overall findings provide support for the view that the pathway from the medial amygdala to the lateral hypothalamus underlying suppression of predatory attack behavior involves a two-neuronal arc: the first neuron projects from the medial amygdala to the medial hypothalamus and its functions are mediated by substance P: the second neuron involves a GABAergic pathway originating in the ventromedial hypothalamus and which projects to the lateral hypothalamus.
Amygdala↗
The use of "inside-out" lateral osteotomies to improve outcome in rhinoplasty.
OBJECTIVE: To evaluate the anatomic effects of the transnasal nasal "inside-out" lateral osteotomy in comparison to a continuous lateral osteotomy to widen the excessively narrow bony nasal pyramid. DESIGN: A series of 4 fresh cadavers were used. Lateral osteotomies were performed on each cadaver. On one side, a continuous lateral osteotomy was performed with a curved, guarded 4-mm osteotome. On the contralateral side, a straight 2-mm osteotome was used to perform the transnasal perforating inside-out lateral osteotomy. The soft tissue was then dissected off the nasal dorsum and the effects were noted. Specifically, the following factors were assessed: (1) the continuity of the internal and external periosteum; (2) any change, without manipulation, of the position of the lateral nasal walls; (3) the mobility of the fragments; and (4) the effect of any of the preceding factors on the nasal airway. RESULTS: All 4 cadavers showed identical results. The external and internal periostea were significantly disrupted on each of the sides with continuous osteotomies. The periosteum was completely preserved on the sides, which underwent inside-out lateral osteotomies, with the exception of the 3 or 4 holes created by the 2-mm osteotome. In each of the sides with continuous osteotomies, the lateral nasal wall was demonstrably unstable, as the segment was, to varying degrees, displaced inwardly. The inside-out lateral osteotomized segments were uniformly lateralized and stable to gentle palpation. Finally, these changes corresponded to a visible effect on the diameter of the nose in the region of the nasal valve. The inward displacement of the segments undergoing continuous osteotomies narrowed the airway. However, the contralateral inside-out osteotomized segments were lateralized, which widened the diameter of the valve. CONCLUSIONS: The inside-out lateral osteotomy is an effective technique for lateral repositioning of the bony lateral sidewall of the nose. It is reproducible and accurate and appears to provide greater preservation of the periosteal support of the bony segments than a continuous osteotomy. This technique provides a more predictable long-term result, with preservation and/or improvement of the nasal airway. The procedure is ideal for managing the bony nasal segment that needs lateralization, particularly in revision rhinoplasties or after trauma.
Cadaver↗
MR diagnosis of discoid lateral menisci of the knee.
OBJECTIVE: To establish explicit criteria for MR imaging diagnosis of discoid lateral menisci of the knee. SUBJECTS: Materials included surgically proved 38 discoid lateral menisci and 36 normal lateral menisci of adult patients. A discriminant analysis was used to identify the optimal cut-off points of the following eight parameters: (1) transverse width of a lateral meniscus on the coronal image at the midportion of a meniscal body; (2) ratio of transverse width between a lateral meniscus and a tibia; (3) height of the lateral margin of a lateral meniscus; (4) difference in height between lateral and medial menisci; (5) transverse area of a lateral meniscus; (6) the number of consecutive sagittal slices demonstrating continuity of the meniscus between the anterior and posterior horns (bow tie appearance); (7) height of the anterior horn of a lateral meniscus on the sagittal image; (8) height of the posterior horn of a lateral meniscus on the same sagittal image. RESULTS: The transverse width of a lateral meniscus on the coronal image was the best parameter, with a cut-off point of 14 mm. Using this criterium, 33 knees of 38 discoid lateral menisci and all 36 normal menisci were correctly identified, yielding an overall accuracy of 93%. CONCLUSION: A discoid lateral meniscus should be present if the transverse width of a lateral meniscus at the midportion of a meniscal body exceeds 14 mm, independent of the tibial width.
Adult↗
The sequential administration of growth hormone-releasing hormone followed 120 minutes later by hexarelin, as an effective test to assess the pituitary GH reserve in man.
OBJECTIVE: GH deficiency, either in children or in adults, is a clinically relevant problem. The diagnosis is based on dynamic tests of GH secretion, which are clear cut on a group basis but highly problematic for individual diagnosis. The controversy surrounding the diagnosis of GH deficiency reflects the absence of a gold standard dynamic test. The synthetic hexapeptide hexarelin and GHRH stimulate GH secretion using different mechanisms. A sequential test has been devised using the administration of GHRH as first stimulus followed 120 minutes later by hexarelin. The two aims of the study were (a) to evaluate the interaction of GHRH and hexarelin, and (b) to devise a sequential test of GH reserve. DESIGN: The GH stimuli used were GHRH (1 microgram/kg i.v.) as a pituitary stimulus, and hexarelin (1 microgram/kg i.v.) as a GH stimulus whose main action is hypothalamic. Each subject was tested twice in order to serve as his own control. Three different studies, each with two duplicate tests, were performed on separate groups of individuals: (a) GHRH followed 120 minutes later by hexarelin and on the second day hexarelin followed 120 minutes later by GHRH; (b) GHRH followed 120 minutes later by GHRH and on the other day hexarelin followed 120 minutes later by hexarelin; (c) GH 0.5 IU i.v. followed 120 minutes later by GHRH and on the other day, the same dose of GH followed 120 minutes later by hexarelin. PATIENTS: Eighteen normal volunteers (12 women, 6 men) after giving informed consent. MEASUREMENTS: Plasma GH levels were measured by time-resolved fluoroimmunoassay; each value shown is the mean +/- SEM of n = 6. RESULTS: GHRH followed 120 minutes later by hexarelin induced two episodes of GH secretion (expressed as mean GH peak, mU/l). The GHRH-mediated GH release showed a mean GH peak of 38.2 +/- 13.6 mU/l and after hexarelin 120 minutes later of 56.7 +/- 18.0 mU/l. The contrary sequence blocked the second stimulus, i.e. the hexarelin-stimulated GH mean peak was 54.7 +/- 18.4, and the GH release 120 minutes later after GHRH was 4.8 +/- 1.9 (P < 0.05 vs GHRH used as first stimulus). In the two sequential tests using the same stimulus, the second GH peak was reduced. In fact, GHRH induced a GH mean peak of 63.8 +/- 21.1 mU/l as first stimulus, greater (P < 0.05) than when GHRH was administered again 120 minutes later (22.0 +/- 5.9 mU/l). Similar results were obtained with hexarelin, with a first mean peak of 70.6 +/- 10.3 mU/l, and a second one 120 minutes later of 13.4 +/- 4.6 mU/l (P < 0.05). The blockade of the second stimulus was not due to the feed-back action of the GH released by the first stimulus. In fact, the i.v. administration of exogenous GH induced a mean GH peak of 168.0 +/- 89.7 and reduced the action of GHRH administered 120 minutes later (26.1 +/- 8.1). The previous administration of GH (mean peak 115.5 +/- 42.0) did not alter the action of hexarelin injected 120 minutes later, showing a mean peak of 71.9 +/- 11.2. The large variability in the stimulatory action of GHRH contrasted vividly with the reproducibility of hexarelin. Furthermore, individually analysed, only one of the 12 subjects tested first with hexarelin, compared to 4 out of 12 tested with GHRH as first stimulus, presented a blunted response (< 13 mU/l). After the sequential stimulus there were no false negatives. CONCLUSION: The sequential administration of GHRH in normal subjects and of hexarelin 120 minutes later provides separate information regarding pituitary GH reserve, of both secretagogues without mutual interference. There were not false negative results to the combined test. This sequentially delayed test may be of some value in the clinical setting for assessing pituitary GH reserve.
Adult↗
Lateral release rates after total knee arthroplasty.
For a total knee replacement to function well, the patella must track centrally in the trochlear groove. A lateral release may be required to ensure such central tracking. During surgery, an evaluation was made of patellar tracking in 178 patients undergoing total knee replacement. The Genesis II prosthesis with a deep-dish tibial insert was used for all the patients. The evaluation was made using the nontouch technique and the axial traction (modified no-touch) technique before and after release of the tourniquet. With the tourniquet still inflated, there were 29 knees in which the patella tilted laterally and 11 additional knees in which the patella subluxed laterally. Using the modified no-touch technique, there were only 12 knees in which the patella tilted laterally and five in which it subluxed laterally. With the tourniquet deflated, only nine of the patellas tilted laterally and three subluxed laterally. It was only in this final group that a lateral release was done for an overall lateral release rate of 6%. Eleven of these 12 knees had a preoperative fixed valgus deformity greater than 10 degrees. Only one lateral release was required for a patient with a preoperative varus deformity. Four patients with a preoperative fixed valgus deformity and a laterally subluxed patella did not require a lateral release. Axial realignment and reconstitution of an anterior trochlear surface by the implant were sufficient to centralize the patella. Had only the no-touch test been used, there would have been 18 unnecessary lateral releases done. When the knees were evaluated radiographically, there was no statistical difference in patellar position between that group and the knees that required a lateral release. Overall in the entire group at 6 weeks after surgery, 105 knees (59%) had no patellar tilt. At 3 months, as quadriceps tone returned to normal, 138 knees (79%) had no patellar tilt. Thirty-three of the remaining 35 knees had a patellar tilt less than 10 degrees. None of the patients had lateral patellar subluxation at any time after surgery.
Aged↗