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By G. Frithjof. Lafayette College. 2018.

The results are dysarthria buy azithromycin 250 mg lowest price, dysphagia azithromycin 100 mg without prescription, dyspnea azithromycin 250 mg mastercard, loss of taste hyperacusis (weakness of stapedius) may also be present best azithromycin 100 mg. Bilateral lesions of the Xth nerve are life- of pain, temperature, and touch on the ipsilateral face and in the oral threatening because of the resultant total paralysis (and closure) of the and nasal cavities; 2) paralysis of ipsilateral masticatory muscles ( jaw de- muscles in the vocal folds (vocalis muscle). Abbreviations AbdNu Abducens nucleus SpTNu Spinal trigeminal nucleus ALS Anterolateral system SpTTr Spinal trigeminal tract BP Basilar pons SSNu Superior salivatory nucleus DVagNu Dorsal motor nucleus of vagus TecSp Tectospinal tract FacNr Facial nerve TriMoNu Trigeminal motor nucleus FacNu Facial nucleus TriNr Trigeminal nerve GINr Glossopharyngeal nerve VagNr Vagus nerve HyNu Hypoglossal nucleus ISNu Inferior salivatory nucleus Ganglia MesNu Mesencephalic nucleus 1 Pterygopalatine ML Medial lemniscus 2 Submandibular MLF Medial longitudinal fasciculus 3 Otic NuAm Nucleus ambiguus 4 Terminal and/or intramural PSNu Principal (chief ) sensory nucleus Review of Blood Supply to TriMoNu, FacNu, DMNu and NuAm, and the Internal Course of Their Fibers STRUCTURES ARTERIES TriMoNu and Trigeminal Root long circumferential branches of basilar (see Figure 5–21) FacNu and Internal Genu long circumferential branches of basilar (see Figure 5–21) DMNu and NuAm branches of vertebral and posterior inferior cerebellar (see Figure 5–14) Motor Pathways 203 Cranial Nerve Efferents (V, VII, IX, and X) Position of Nucleus and Internal Route of Fibers TriMotNu MesNu MLF PSNu TecSp Motor root Structures Innervated ALS of TriNr Masticatory muscles and ML tensor tympani, TriMotNu tensor veli palatini, Motor root mylohyoid, BP of TriNr digastric (ant. Also illustrated is the somatotopy of those fibers originating ataxia one might expect to see in patients with a spinal cord hemisection from the spinal cord. These fibers enter the cerebellum via the resti- (as in the Brown-Sequard syndrome) is masked by the hemiplegia resulting form body, the larger portion of the inferior cerebellar peduncle, or from the concomitant damage to lateral corticospinal (and other) fibers. After these fibers Friedreich ataxia (hereditary spinal ataxia) is an autosomal recessive dis- enter the cerebellum, collaterals are given off to the cerebellar nuclei order the symptoms of which usually appear between 8 and 15 years while the parent axons of spinocerebellar and cuneocerebellar fibers of age. There is degeneration of anterior and posterior spinocerebellar pass on to the cortex, where they end as mossy fibers in the graunular tracts plus the posterior columns and corticospinal tracts. Although not shown here, there are important ascending spinal tive changes are also seen in Purkinje cells in the cerebellum, in poste- projections to the medial and dorsal accessory nuclei of the inferior rior root ganglion cells, in neurons of the Clarke column, and in some olivary complex (spino-olivary fibers). The axial and appendicular ataxia seen (as well as the principal olivary nucleus) project to the cerebellar cor- in these patients correlates partially with the spinocerebellar degener- tex and send collaterals into the nuclei (see Figure 7-18 on page 206). Abbreviations ACNu Accessory (external or lateral) cuneate PSCT Posterior (dorsal) spinocerebellar tract nucleus PSNu Principal (chief ) sensory nucleus of ALS Anterolateral system trigeminal nerve AMV Anterior medullary velum Py Pyramid ASCT Anterior (ventral) spinocerebellar tract RB Restiform body Cbl Cerebellum RSCF Rostral spinocerebellar fibers CblNu Cerebellar nuclei RuSp Rubrospinal tract CCblF Cuneocerebellar fibers S Sacral representation DNuC Dorsal nucleus of Clarke SBC Spinal border cells FNL Flocculonodular lobe SCP Superior cerebellar peduncle IZ Intermediate zone SpTNu Spinal trigeminal nucleus L Lumbar representation SpTTr Spinal trigeminal tract MesNu Mesencephalic nucleus T Thoracic representation ML Medial lemniscus TriMoNu Trigeminal motor nucleus PRG Posterior (dorsal) root ganglion VesNu Vestibular nuclei Review of Blood Supply to Spinal Cord Grey Matter, Spinocerebellar Tracts, RB, and SCP STRUCTURES ARTERIES Spinal Cord Grey branches of central artery (see Figure 5–6) PSCT and ASCT in Cord penetrating branches of arterial vasocorona (see Figure 5–6) RB posterior inferior cerebellar (See Figure 5–14) SCP long circumferential branches of basilar and superior cerebellar (see Figure 5–21) Cerebellum posterior and anterior inferior cerebellar and superior cerebellar Cerebellum and Basal Nuclei (Ganglia) 205 Spinocerebellar Tracts Position of SCP AMV ASCT SCP MesNu TriMoNu ML PSNu ASCT on SCP Lobules II-IV Lobules II-IV Ant. Lobe Lobule V Lobule V Recrossing ASCT fibers in Cbl CblNu CblNu RB RB FNL Post. Lobe CCblF Lobule VIII Lobule VIII ACNu RSCF PRG Somatotopy Position Lamina VII VesNu at C4-C8 PSCT RB ASCT SpTTr & Nu DNuC ASCT ALS + RuSp Intermediate zone (IZ) and "spinal border" Py cells (SBC) PRG DNuC PSCT PSCT T L S IZ ASCT L T ASCT SBC 206 Synopsis of Functional Components, Tracts, Pathways, and Systems Pontocerebellar, Reticulocerebellar, Olivocerebellar, Ceruleocerebellar, Hypothalamocerebellar, and Raphecerebellar Fibers 7–18 Afferent fibers to the cerebellum from selected brainstem ar- ticotropin ( )-releasing factor are present in many olivocerebellar eas and the organization of corticopontine fibers in the internal capsule fibers. Ceruleocerebellar fibers contain noradrenalin, histamine is and crus cerebri as shown here. The cerebellar peduncles are also indi- found in hypothalamocerebellar fibers, and some reticulocerebellar cated. Pontocerebellar axons are mainly crossed, reticulocerebellar fibers contain enkephalin. Serotonergic fibers to the cerebellum arise fibers may be bilateral (from RetTegNu) or mainly uncrossed (from from neurons found in medial areas of the reticular formation (open LRNu and PRNu), and olivocerebellar fibers (OCblF) are exclusively cell in Figure 7–18) and, most likely, from some cells in the adjacent crossed. Raphecerebellar, hypothalamocerebellar, and ceruleocerebel- raphe nuclei. Although all af- Clinical Correlations: Common symptoms seen in patients with ferent fibers to the cerebellum give rise to collaterals to the cerebellar lesions involving nuclei and tracts that project to the cerebellum are nuclei, those from pontocerebellar axons are relatively small, having ataxia (of trunk or limbs), an ataxic gait, dysarthria, dysphagia, and dis- comparatively small diameters. Olivocerebellar axons end as climbing orders of eye movement such as nystagmus. These deficits are seen in fibers, reticulocerebellar and pontocerebellar fibers as mossy fibers, and some hereditary diseases (such as olivopontocerebellar degeneration, ataxia hypothalamocerebellar and ceruleocerebellar axons end in all cortical telangiectasia, or hereditary cerebellar ataxia), in tumors (brainstem layers. These latter fibers have been called multilayered fibers in the lit- gliomas), in vascular diseases (lateral pontine syndrome), or in other con- erature because they branch in all layers of the cerebellar cortex. Abbreviations AntLb Anterior limb of internal capsule PonNu Pontine nuclei CblNu Cerebellar nuclei PO Principal olivary nucleus CerCblF Ceruleocerebellar fibers PPon Parietopontine fibers CPonF Cerebropontine fibers PRNu Paramedian reticular nuclei CSp Corticospinal fibers Py Pyramid DAO Dorsal accessory olivary nucleus RB Restiform body FPon Frontopontine fibers RCblF Reticulocerebellar fibers Hyth Hypothalamus RetLenLb Retrolenticular limb of internal capsule HythCblF Hypothalamocerebellar fibers RNu Red nucleus IC Internal capsule RetTegNu Reticulotegmental nucleus LoCer Nucleus (locus) ceruleus SCP Superior cerebellar peduncle LRNu Lateral reticular nucleus SubLenLb Sublenticular limb of internal capsule MAO Medial accessory olivary nucleus SN Substantia nigra MCP Middle cerebellar peduncle TPon Temporopontine fibers ML Medial lemniscus NuRa Raphe nuclei Number Key OCblF Olivocerebellar fibers 1 Nucleus raphe, pontis OPon Occipitopontine fibers 2 Nucleus raphe, magnus PCbIF Pontocerebellar fibers 3 Raphecerebellar fibers PostLb Posterior limb of internal capsule Review of Blood Supply to Precerebellar Relay Nuclei in Pons and Medulla, MCP, and RB STRUCTURES ARTERIES Pontine Tegmemtum long circumferential branches of basilar plus some from superior cerebellar (see Figure 5–21) Basilar Pons paramedian and short circumferential branches of basilar (See Figure 5–21) Medulla RetF and IO branches of vertebral and posterior inferior cerebellar (see Figure 5–14) MCP long circumferential branches of basilar and branches of anterior inferior and superior cerebellar (see Figure 5–21) RB posterior inferior cerebellar (see Figure 5–14) Cerebellum and Basal Nuclei (Ganglia) 207 Pontocerebellar, Reticulocerebellar, Olivocerebellar, Ceruleocerebellar, Hypothalamocerebellar, and Raphecerebellar Fibers Position of Associated Tracts and Nuclei AntLb (FPon) PostLb (PPon) IC SubLenLb Hyth (TPon) RetLenLb (OPon) CPonF HythCblF LoCer ML RetTegNu CerCblF RNu SCP SN PPon MCP OPon 1 TPon FPon PonNu NuRa PCblF 3 2 CblNu RetTegNu OCblF MCP ML DAO RB CPonF PCblF RCblF CSp PO LRNu PonNu PRNu MAO PRNu RB OCblF LRNu PO Py OCblF PCblF CerCblF 208 Synopsis of Functional Components, Tracts, Pathways, and Systems Cerebellar Cortioconuclear, Nucleocortical, and Corticovestibular Fibers 7–19 Cerebellar corticonuclear fibers arise from all regions of the Lesions involving midline structures (vermal cortex, fastigial nu- cortex and terminate in an orderly (mediolateral and rostrocaudal) se- clei) and/or the flocculonodular lobe result in truncal ataxia (titubation quence in the ipsilateral cerebellar nuclei. These patients may also have a fibers from the vermal cortex terminate in the fastigial nucleus, those wide-based (cerebellar) gait, are unable to walk in tandem (heel to toe), from the intermediate cortex terminate in the emboliform and globo- and may be unable to walk on their heels or on their toes. Generally, sus nuclei, and those from the lateral cortex terminate in the dentate nu- midline lesions result in bilateral motor deficits affecting axial and cleus. Also, cerebellar corticonuclear fibers from the anterior lobe typ- proximal limb musculature. Cerebellar corticovestibu- emboliform, and dentate nuclei results in various combinations of the lar fibers originate primarily from the vermis and flocculonodular lobe, following deficits: dysarthria, dysmetria (hypometria, hypermetria), dysdi- exit the cerebellum via the juxtarestiform body, and end in the ipsilat- adochokinesia, tremor (static, kinetic, intention), rebound phenomenon, un- eral vestibular nuclei. One of the more Nucleocortical processes originate from cerebellar nuclear neurons commonly observed deficits in patients with cerebellar lesions is an in- and pass to the overlying cortex in a pattern that basically reciprocates tention tremor, which is best seen in the finger-nose test. The finger-to-fin- that of the corticonuclear projection; they end as mossy fibers. Some ger test is also used to demonstrate an intention tremor and to assess nucleocortical fibers are collaterals of cerebellar efferent axons. The heel-to-shin test will show dysmetria in the lower cerebellar cortex may influence the activity of lower motor neurons extremity. If the heel-to-shin test is normal in a patient with his/her through, for example, the cerebellovestibular-vestibulospinal route.

Total canalicular bile flow is composed of bile acid–dependent flow ATP ADP+Pi and bile acid–independent flow 500 mg azithromycin with mastercard. Hepatocyte up- take of free and conjugated bile salts is Na -dependent and Bile Secretion Is Primarily Regulated by a mediated by bile salt–sodium symport (Fig discount 100mg azithromycin with amex. The Feedback Mechanism quality 250 mg azithromycin, With Secondary energy required is provided by the transmembrane Na Hormonal and Neural Controls gradient generated by the Na /K -ATPase 100 mg azithromycin with amex. This mecha- nism is a type of secondary active transport because the en- The major determinant of bile acid synthesis and secretion ergy required for the active uptake of bile acid, or its con- by hepatocytes is the bile acid concentration in hepatic por- jugate, is not directly provided by ATP but by an ionic tal blood, which exerts a negative-feedback effect on the gradient. The free bile acids are reconjugated with taurine synthesis of bile acids from cholesterol. Hepatocytes also make new of bile acids in portal blood also determines bile acid–de- bile acids from cholesterol. Between meals, the portal blood concen- tocytes by a carrier located at the canalicular membrane. After a meal, there is increased delivery of bile salts in cyte and the canaliculus lumen. CCK is secreted by the intestinal mucosa when fatty Bilirubin is secreted by hepatocytes via an active process. CCK causes Although the secretion of cholesterol and phospholipid is contraction of the gallbladder, which, in turn, causes in- not well understood, it is closely coupled to bile salt secre- creased pressure in the bile ducts. The osmotic pressure generated as a result of the se- rises, the sphincterof Oddi relaxes (another effect of CCK), cretion of bile salts draws water into the canaliculus lumen and bile is delivered into the lumen. When the mucosa of the small intestine is exposed to acid in the chyme, it releases secretin into the blood. As the name cretin stimulates HCO3 secretion by the cells lining the implies, this component of canalicular flow is not depend- bile ducts. As a result, bile contributes to the neutralization ent on the secretion of bile acids (see Figs. The Na /K -ATPase plays an important role in Gastrin stimulates bile secretion directly by affecting the bile acid-independent bile flow, a role that is clearly liver and indirectly by stimulating increased acid produc- demonstrated by the marked reduction in bile flow when an tion that results in increased secretin release. CHAPTER 27 Gastrointestinal Secretion, Digestion, and Absorption 495 During pregnancy, the high circulating level of estrogen Liver can reduce bile acid secretion. Conjugation The biliary system is supplied by parasympathetic and sympathetic nerves. Parasympathetic (vagal) stimulation results in contraction of the gallbladder and relaxation of Primary Secondary bile salts bile salts ~500 mg bile the sphincter of Oddi, as well as increased bile formation. By contrast, stimu- Portal circulation lation of the sympathetic nervous system results in reduced bile secretion and relaxation of the gallbladder. Gallbladder Gallbladder Bile Differs From Hepatic Bile Colon Bile Gallbladder bile has a very different composition from he- storage Bile patic bile. The principal difference is that gallbladder bile is salts Bile more highly concentrated. Water absorption is the major acids mechanism involved in concentrating hepatic bile by the 1 2 gallbladder. Water absorption by the gallbladder epithe- Deoxycholic lium is passive and is secondary to active Na transport via Conjugated Free 3 4 acid a Na /K -ATPase in the basolateral membrane of the ep- bile bile Lithocholic ithelial cells lining the gallbladder. As a result of isotonic salts acids acid fluid absorption from the gallbladder bile, the concentra- Small Terminal Cecum tion of the various unabsorbed components of hepatic bile intestine ileum increases dramatically—as much as 20-fold. Bile salts are recycled out of the small intestine The Enterohepatic Circulation Recycles Bile Salts in four ways: (1) passive diffusion along the small intestine (plays Between the Small Intestine and the Liver a relatively minor role); (2) carrier-mediated active absorption in the terminal ileum (the most important absorption route); (3) de- The enterohepatic circulation of bile salts is the recycling conjugation to primary bile acids before being absorbed either of bile salts between the small intestine and the liver. The passively or actively; (4) conversion of primary bile acids to sec- total amount of bile acids in the body, primary or second- ondary bile acids with subsequent absorption of deoxycholic acid. The enterohepatic circulation of bile acids in Although bile salt and bile acid absorption is extremely ef- this pool is physiologically extremely important.

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Gilula Mallinckrodt Institute of Radiology 500 mg azithromycin overnight delivery, Washington University School of Medicine 100 mg azithromycin with visa, St order 250 mg azithromycin with visa. Another cause for diffuse swelling along one side of the wrist or finger can be tenosynovitis azithromycin 500mg visa. This chapter will emphasize general principles when as- The evaluation of alignment (“A”) allows deviations sessing a variety of lesions of the hand and wrist. Angular deformities are proach to analyzing the wrist and hand bones will be pro- commonly seen in arthritis. Dislocations and carpal in- vided, followed by a discussion of applications of these stabilities manifest as abnormalities in alignment. Acute bone demineralization presents possible to cover all of musculoskeletal imaging and as subcortical bone loss in the metaphyseal areas and at pathology in a short article; however, some major points the ends of bones, in regions of increased vascularity of will be emphasized in each of these different areas, with bones. A typical example is the young person who has the most emphasis placed on complex carpal trauma. Diffuse even demineralization commonly develops over longer Overview of Analysis periods of time and may be seen in older people with dif- fuse osteopenia of age and also from prolonged disuse. Forrester, looking at the muscu- Focal osteopenia, especially associated with cortical loskeletal system anywhere can be evaluated by the “A, loss, should raise the question of infection or a more B, C, D, ‘S” system. Utilizing these principles the margins of these joints and bones for cartilage space will help keep one from missing major observations. Starting with “S” for soft tissues will keep one from for- “D” refers to the distribution of abnormalities. Recognizing soft-tissue most vividly exemplified by the distribution of erosions, (“S”) abnormalities will point to an area of major abnor- as may be seen distally in psoriasis and more proximally mality and should trigger a second or third look at the in rheumatoid arthritis. The soft tissues dor- lelism, (2) overlapping articular surfaces, and (3) three sally over the carpal bones are normally concave. All three can be especially applied to the the soft tissues over the dorsum of the wrist are straight carpal bones. Parallelism refers to the fact that any anatomic line volar to the distal radius suggests deep swelling when structure that normally articulates with an adjacent anatom- it is convex outward, as normally it should be straight or ic structure should show parallelism between the articular concave. Soft-tissue swelling along the radial and ul- cortices of those adjacent bones. This is exactly how jigsaw nar styloids may be seen in synovitis or trauma. If there is a piece of a jigsaw puzzle out of along the radial or ulnar side of a finger joint can indi- place, then that piece loses its parallelism to adjacent cate collateral ligament injury. Anatomically, this would cause overlapping articu- ment exist along the radial side of the index finger and lar surfaces. Therefore, the concepts of parallelism and the ulnar side of the small finger. If there is overlap ferentially around one interphalangeal or metacarpopha- of normally articulating surfaces, there should be disloca- langeal joint is highly suggestive of capsular or joint tion or subluxation at the site of those overlapping surfaces. Gilula This does not apply if one bone is foreshortened or bent, as Trauma with overlapping phalanges on a PA view of a flexed fin- ger. In that situation, one phalanx would overlap the adja- Traumatic conditions of the wrist basically can be classi- cent phalanx, but in the flexed PA position one would not fied as fractures, fracture-dislocations, and soft-tissue ab- normally see parallel articular surfaces at that joint. The third alignment concept refers to the fact that three Analysis of the carpal arcs, overlapping articular sur- carpal arcs can be drawn in any normal wrist when the wrist faces, and parallelism will help determine what exact and hand are in a neutral position, i. Arc I is a smooth curve along the bones normally parallel each other also identifies which proximal convex surfaces of the scaphoid, lunate and tri- bones have moved together as a unit away from a bone quetrum. Arc II is a smooth arc drawn along the distal con- that has overlapping adjacent surfaces. Arc III is a fractures and dislocations about the wrist are of the per- smooth arc that is drawn along the proximal convex sur- ilunate type, in which there is a dislocation with or with- faces of the capitate and hamate [3, 6]. When one of these out adjacent fractures taking place around the lunate. The arcs is broken at a joint, then something is probably wrong additional bones that may be fractured are named first with that joint, as ligament disruption; or when broken at a with the type of dislocation mentioned last.

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These processes cheap azithromycin 500mg with amex, like all metabolic procedures in hematopoetic cells with replacement of fat cells resulting the human body discount 500mg azithromycin fast delivery, are energy consumptive and dependent in a change of the fat/water ratio (Fig discount azithromycin 100mg without a prescription. The hematopoetic 201:519-523 cells occupy more than 50% of the marrow space (Courtesy of Rainer Bartl purchase azithromycin 500 mg online, MD, Großhadern Clinic) Fig. A decrease normal hematopoetic cells and, most important for MR imaging, of cellular marrow with age is also found in the spine. From Vande no fat cells had remained (Courtesy of Rainer Bartl, MD, Berg BC et al. Inversion recov- ery sequences with a short inversion time (STIR) can To prove or rule out metastasis of the bone, the preferred suppress fat signal by suppressing short T1-relaxation imaging modality must be able to image the whole skele- times. Bone scintigraphy is widely used, but is an indirect PD- and T2-weighted spin echo sequences also highlight method, showing indiscriminate changes of bone metab- the increased signal of water. MR imaging can detect tumor infiltration of the intensity of fat on T2-weighted fast spin echo images bone marrow space before metabolic or structural (FSE), FSE-sequences without fat suppression are not changes of trabecular or cortical bone are depicted on useful for bone marrow imaging. The most important factor to cut down scanner time to Normal hematopoetic bone marrow with near to equal acceptable times for whole body MR imaging protocols amounts of fat- and water-containing cells is depicted on are the use of appropriate hardware and sequences. Two sequences with subtraction of the transverse magnetization principle (manufacturer dependent) techniques use either of fat and water, such as opposed phase long TR GRE se- multiple surface coils and cover the whole body by these quences, with a very low signal intensity. Spin-dephasing, coils or use a especially adopted circularly polarized due to effects of magnetic susceptibility, add to the sub- body coil. For the spine, a phased array coil should be traction effect of the fat- and water-magnetization and re- used. A tendency not to increase the field-of-view but to sult in a signal void of normal hematopoetic marrow on opposed-phase GRE images. A shift in the fat-water ratio shorten the magnet and to move the patient through the results in an increase of signal intensity, and therefore bone center of the magnet while acquisition of the data is rec- marrow infiltrating processes can be detected using op- ognized in the hard ware development. GRE sequences are sensitive to by using water sensitive STIR-sequences and FSE im- pulsation and moving artifacts which can cause problems ages, specificity is improved by adding T1-weighted fast when using a spine array coil with a large FoV. Standard imaging of the marrow space should always Whole body MR imaging with rolling (moving) table include T1-weighted images and a sequence sensitive to detects more lesions than bone scintigraphy. The dedicated techniques described below are on- bone scans tend to detect more lesions in the ribs and the ly indicated in special clinical settings. On bone scan only the lesion to the rib on the right side is obvious (a, b). The STIR image revealed multiple metastasis in the spine (c) (Courtesy Mark Steinborn, MD, Großhadern Clinic) 76 A. These locations are clinically more important than cific imaging the bone marrow. Scintigraphy grade lesions, espe- blood half-time of the 5-15 nm small particles these cially in the spine, significantly more frequent as uncer- preparations reduce signal intensity of bone marrow on tain of origin compared to MRI, underlining the low MR images. MR imaging offers morpho- macrophages of the reticulo endothelial system (RES) logic information, which can be important for treatment with phagocytic activity against ultrasmall superparamag- planning and MRI detects tumor-associated complica- netic iron oxide (USPIO) particles dependent on the size tions and organ metastasis in the lung and liver. The resulting signal drop is more pro- marrow spaces of flat bones and motion artifacts in the nounced using the ultra small particles (USPIO). The clinical relevance of this is given on- The diagnostic mechanism of USPIO-imaging of bone ly in cases where these lesions are solitary findings and marrow disorders is similar to SPIO-imaging of the liver. Whole body MR imag- exhibiting a pronounced signal loss following the appli- ing is only surpassed by whole body PET/CT-imaging con- cation of USPIO particles. In the case of malignant bone cerning sensitivity and specificity in detection and staging marrow infiltration, no signal drop will be observed on of tumors including the bone marrow. USPIO imaging of the bone marrow can also be used for evaluation of the blood-bone marrow barrier e. It was shown, that also Gadolinium-enhanced Bone Marrow Imaging SPIO decreases the signal intensity of bone marrow. Superparamagnetic iron oxides are taken up by normal It was believed that bone marrow in general does not en- and hypercellular reconverted bone marrow, but not by hance with gadolinium, which is not true for red marrow. When the upper limit for the normal percentage en- Diffusion Imaging of the Bone Marrow hancement value is 2 SD above the normal mean per- centage enhancement, cut-off values for abnormal Diffusion-weighted imaging (DWI) is another method of gadolinium uptake in bone marrow is 43.

During the course of the different seronegative Reiter’s syndrome cheap azithromycin 250mg with visa, which extend above the vertebral- spondyloarthritides azithromycin 250 mg, a variety of changes affect the dis- body margins purchase azithromycin 500mg line, are asymmetric cheap azithromycin 250mg, and relatively robust. Another late man- with ankylosing spondylitis and usually begins at the ifestation of ankylosing spondylitis is the advanced, dis- thoracolumbar and lumbosacral junctions. Subsequently, covertebral destructive Andersson’s lesion, of which there the rest of the lumbar, upper thoracic and cervical spine are two types: type A or inflammatory; and type B or are affected. Both types occur after long-term dis- sertion of the outer fibers of the annulus fibrosus is ini- ease. Inflammatory type A is characterized by defects of tially demonstrated as discrete erosions of the superior the vertebral-body endplates surrounded by broad perifo- and inferior portions of the vertebral bodies followed by cal sclerosis with narrowing of the intervertebral discs. Paucity structive and reactive changes are called Romanus le- or absence of syndesmophytes is another feature. Non-in- sions, spondylitis anterior, or spondylitis marginalis flammatory type B may be seen even later, 10 or more (Fig. Typically, an More pronounced inflammatory destruction may cause ankylosed spine with numerous syndesmophytes is “planed-down” corners which, together with anterior pe- riosteal apposition, produce “squaring” or “barreling” of demonstrated. Initial marginal destruction is fol- affected, usually at the thoracolumbar junction. It may be lowed by ossification of the outer fibers of the annulus fi- widened or narrowed with pronounced bone destruction. It represents boring vertebral bodies forming syndesmophytes, which pseudoarthrosis due to trauma or stress and extends from are typical of ankylosing spondylitis. The ra- phytes are delicate and symmetric, and connect the ver- diological differentiation between type A and type B dis- tebral-body margins (marginal syndesmophytes). They covertebral lesions is of practical importance since are different from the parasyndesmophytes (or nonmar- pseudoarthrosis may require spinal stabilization. It has been shown that on Gd-DTPA MRI atic arthritis, pronounced erosive changes may cause ver- seronegative spondylitis has a variable signal pattern and tical subluxation of the axis with basilar invagination of degree of contrast enhancement, which may reflect the the odontoid. MRI studies clearly demonstrate the degree evolutionary stages of discovertebral enthesitis in anky- of compression of the medulla oblongata. At an early stage of spinal enthesitis, the discovertebral junctions are of low signal intensity on T1-weighted spin echo images. High signal intensity on References T2-weighted images and marked contrast enhancement on T1-weighted post-contrast images surrounding bone 1. Resnick D, Niwayama G (1995) Diagnosis of bone and joint erosion reflect inflammatory edema and hyperemia. Saunders, Philadelphia may identify early erosive changes in radiographically 2. Modic TM, Masaryk TJ, Ross JS (1992) Magnetic resonance MR studies show high-signal-intensity vertebral-body imaging of the spine. Year book Medical, St Louis corners on T1-weighted and T2-weighted images without 4. Moll JMH, Haslock I, Mac Rae IF, Wright V (1974) Associa- fatty marrow transformation. Medicine (Baltimore) 53:343-364 lations with potentially life-threatening complications is 6. Jevtic V, Kos-Golja M, Rozman B, McCall I (2000) Marginal ligamentum transversum is present. Widening of the pre- erosive discovertebral “Romanus” lesions in ankylosing dental space by more than 3 mm in adults and 5 mm in spondylitis demonstrated by contrast enhanced Gd-DTPA children during flexion may be demonstrated by radi- magnetic resonance imaging. Skeletal Radiol 29:27-33 IDKD 2005 Degenerative Diseases of the Spine D. McCall2 1 Department of Radiology, University Hospital, Zurich, Switzerland 2 Department of Diagnostic Imaging, The Robert Jones & Agnes Hunt Hospital, Shropshire, UK Introduction cytes and has ground substance.

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