Bertil Blok, MD, PhD

• Department of Urology
• Erasmus Medical Center Rotterdam, Netherlands

Therefore spasms in right side of abdomen discount robaxin 500 mg mastercard, echocardiography remains the mainstay in the diagnosis of the various forms of congenital heart disease muscle relaxer 86 67 order genuine robaxin online. The converse is true with increased vascularity-the lungs appear whiter with more vessels apparent spasms near kidney order robaxin 500mg. Decreased vascularity occurs in those conditions in which the blood is unable to leave the right side of the heart to enter the lungs spasms near ovary purchase robaxin online now. These may include tetralogy of Fallot spasms urethra generic 500mg robaxin amex, as well as pulmonary and tricuspid atresia spasms around heart order generic robaxin on-line. Note that the calipers measure this blindending tubular structure as greater than 6 mm. The most pronounced edema may be seen as alveolar edema manifesting as fluffy opacities that typically begin in the perihilar region and proceed to the periphery. The echotexture of the thymus is pre dominantly hypoechoic when compared to the liver and spleen with punctate and linear echogenic foci representing fatty tissue interspersed among the thymic tissue. Bowel obstruction can be divided into two broad categories of upper and lower obstruction. Depending on the level of obstruction, bowel obstruction may present clinically with feeding intolerance, bilious emesis, failure to pass meconium, and abdominal distension. The differential diagnosis for both upper and lower bowel obstructions is broad, and only the most frequently encountered entities will be discussed in the following. Single image obtained during the voiding portion of a voiding cystourethrogram in a male with posterior urethral valves. This may proceed to Esophageal atresia Esophageal atresia with or without a tracheoesophageal fistula is the most proximal of the bowel obstructions and has a number of different forms, based on the configuration of the esophagus with variable fistulous connections to the trachea. Frontal radiograph of the pelvis in a male with an early slipped capital femoral epiphysis who presented with leftsided hip pain. The arrow indicates subtle widening of the physis when compared to the right side (a). Frog leg lateral view of the normal right hip shows appropriate alignment of the femoral head and heck (b). Frog leg lateral view of the affected left hip shows the offset capital femoral epiphysis. The findings are much more apparent on this view reinforc ing the fact that two views are needed to make this diagnosis (c). Illustration indicating the structures obtained during a coronal view of the hip in an infant. Additionally, the arrow indicates blunting or rounding ilium/acetabular roof angle (c). Frontal radiograph of a neonate with a large multicystic mass filling the right hemithorax and displacing the mediastinum to the left with compression of the left lung. Frontal radiograph of a neonate with hyperinflation of the right hemithorax resulting in displacement of the mediastinum to the left with compression of the left lung. If there is question of a mass versus normal thymus, ultrasound should be the firstline imaging modality used. Frontal radiograph of the abdomen in a neonate with a very proximal bowel obstruction. The stomach and proximal duodenum are dilated creating a "doublebubble" appearance. This sign classically refers to duodenal atresia but can be seen in other forms of duodenal obstruction (a). Note that one cannot differentiate small bowel and colon in neonates based on the appearance of the gasfilled loops, as the small bowel lacks its normal folds and the colon lacks the distinctive haustra (c). The etiology of this condition is unknown but is frequently seen in conjunction with other anomalies; up to one third of patients with duodenal atresia have trisomy 21. Microcolon develops when there is nonuse of the colon in antenatal life, that is, when no succus is able to make its way into the colon, it will remain small. Thus, the more distal the obstruction, the greater the chances are for microcolon. Contrast enemas may be performed prior to sur gical intervention to assess for the presence of multiple atresias. As a result, the affected segment of bowel remains in a fixed, narrow configuration causing varying degrees of bowel obstruction. In the neonatal period, most patients present with the inability to pass meconium within the first 24 h after birth. If the aganglionic segment is limited to the rectum and distal sigmoid, there will be a rectosigmoid ratio of less than one due to the relatively small caliber of the rectum when compared to the normalcaliber colon (in normal children, the rectum is of larger caliber than the colon). The hallmark findings are a smallcaliber left colon with a change in caliber near the splenic flexure with multiple filling defects due to the presence of meconium. Meconium ileus Although the names are similar, meconium plug and meconium ileus are distinct entities with vastly different clinical implications. Meconium ileus primarily affects the distal ileum with secondary effects seen in the colon. Due to the tenacious meconium seen in this patient population, the ileum becomes obstructed resulting in underuse of the colon in antenatal life with subsequent microco lon. A "mass" representing the inspissated meconium may be seen in the right lower quadrant. With the improvements in prenatal imaging, this diagnosis can be suggested in utero. Relevant imaging findings seen on prenatal imaging are a distended urinary bladder and posterior urethra creating a "keyhole" appearance. The patient is positioned such that the penis can be imaged obliquely while he is voiding. The presence of the valves, demon strated as a linear filling defect at the base of the verumontanum, may be difficult to visualize. If this diagnosis is missed, renal failure may develop due to long standing obstructive uropathy. Even the presence of a gallbladder does not exclude the diagnosis of biliary atresia. Using a radionuclide such as mebrofenin that is excreted by the biliary system, the patency of the extrahepatic biliary system can be ascertained. To increase the sensitivity of this test, phenobarbital is administered for 5 days prior to the examination. The imaging will demonstrate normal uptake of the radiotracer in the hepatic parenchyma with no excretion into the small bowel. Prompt diagnosis is important as the Kasai procedure or hepatoportojejunostomy is the pallia tive procedure used to drain the bile and is more efficacious the earlier in life it is performed. The etiology of this condition is unknown but is thought to be due to an abnor mally short course of the ureter through the bladder wall resulting in an incompetent insertion. Reflux of urine up the ureter and into the kidney is thought to predispose affected individuals to pyelonephritis with subsequent renal scarring and renal insufficiency. The diagnosis may be suspected antenatally by visualizing intermittent dilatation of the renal pelvis. The bladder is then filled to capacity to look for the presence of reflux up the ureters. Factors predisposing to this condition include female gender, breech presentation, and Pediatric imaging 225 firstborn. Infants are screened clinically with the Ortolani and Barlow maneuvers performed at birth and during followup well child exams. The percentage of coverage of the femoral head is determined as well as the alpha angle, a measurement of how shallow the acetabulum is. This is an important diagnosis to make as the longterm conse quences, if left untreated, may be severe, including avascular necrosis and earlyonset osteoarthrosis. There is diffuse demineralization of the bones, giving the bones a darker than normal appearance on radiograph. However, it is an important entity to consider when evaluating a child with multiple fractures. The preferred location for the tip is the "high position" extending from T6 to T10, but the low position from L3 to L5 is also acceptable. Not infrequently, the tips of these catheters are malpositioned, most frequently located in one of the portal veins. This results in a palpable mass in the neck as well as turning of the head toward the side of the spasming muscle. Invasion of the fascial planes, lymphadenopathy, or a delayed age at initial presentation should prompt consideration of other diagnoses, such as rhabdomyosarcoma. Radiographs limited to the chest, while helpful in determining the location of the Aspiration or ingestion of foreign bodies is a not infrequent diagnosis made in the pediatric population. While classically occur ring in the toddler age group, this can also be seen in younger children, most frequently courtesy of older siblings. Chest radio graphs can be used to differentiate whether the foreign body is in the trachea or proximal esophagus; the trachea is more anteriorly located on lateral radiographs and is easily visible as a vertically oriented air column. Aspirated foreign bodies frequently present with respiratory distress in the acute setting but may also present with recurrent infections due to airway obstruction. The radiographic signs can be subtle when radiolucent foreign bodies are aspirated. The most common finding is hyperinflation of the affected lung due to ballvalve phenomenon. This can be further assessed by obtain ing bilateral decubitus views (views with the patient on his or her side). In a patient with an aspirated foreign body in a bronchus, the downward side will not normally collapse due to the pressure of the hyperin flated lung. The most worrisome ingested objects are batteries, due to the risk of corrosion (which can occur within hours of ingestion), and multiple magnets, due to the risk of perforation should they be on opposite sides of the bowel wall. Followup radiographs can be obtained on a casebycase basis to follow the object through the alimentary tract. Imaging studies, however, can be useful in excluding other causes of respiratory distress as well as showing potential complica tions. On chest radiographs, hyperinflation is seen with varying degrees of bronchial cuffing due to inflammation of the airways. Roving atelectasis, seen as migrating opacities, is also frequently seen due to mucus plugging the inflamed airways. When present, an appendicolith can be seen as an echogenic or bright focus that demonstrates posterior acoustic shadowing. In young children, the etiology is unknown but may be due to enlarged lymphoid tissue in the setting of recent illness. These patients classically present with lethargy, intermittent abdominal pain, and currant jelly stools. An abdominal radiograph can suggest the diagnosis by demonstrating a soft tissue mass in the right abdomen with dilatation of multiple loops of small bowel. On transverse views, the intussuscepted bowel will have a targetoid appearance due to the bowel enveloped on itself. In current practice, an air enema is the most frequently employed means of reduction. With this technique, after radiographs are obtained to confirm the lack of free air, the patient is placed in a prone position and a rectal catheter is placed. With the buttocks pressed firmly together to prevent the egress of air, air is slowly pumped into the rectum. As intussusceptions frequently recur several times within a week after initial presentation, airreduction enemas may be required multiple times in the same patient. It is important to realize that this scan does not identify the diverticulum itself but localizes to the ectopic gastric mucosa. The etiology of this condition is unknown, and a number of factors have been sug gested, including infection, ischemia, and early enteral feeding. En face, these are harder to delineate from stool as it may appear as bubbly lucencies. The presence of portal venous gas, gas within the portal vein appearing as branching lucencies over the liver, should also be closely monitored. Appendicitis Malrotation with and without volvulus As in adults, appendicitis is a frequent cause of abdominal pain. In children, appendicitis and resulting complications are also included in the differential diagnosis of small bowel obstruction.

The offmidline location is helpful in discriminating these tumors from chordomas muscle relaxer ketorolac order robaxin 500mg on-line, which are usually midline muscle relaxant magnesium order generic robaxin on line. The oral cavity extends from the lips posteriorly to a ring of structures that include circumvallate papillae of the tongue muscle relaxant johnny english purchase robaxin canada, anterior tonsillar pillars muscle relaxant lorazepam robaxin 500mg otc, and soft palate muscle relaxant used for cheap robaxin 500 mg without prescription. It includes the buccal mucosa muscle relaxant oral order robaxin 500mg online, alveolar ridges, oral tongue, floor of mouth, retromolar trigone, and hard palate. The oropharynx is situated directly posterior to the oral cavity and includes the posterior third of the tongue (base of tongue), valleculae, palatine tonsils and tonsillar fossa, soft palate, and uvula. The nasopharynx lies above the oropharynx and extends from the base of the skull to the superior surface of the soft palate. Laterally, there is a cartilaginous opening of the eustachian tube known as torus tubarius. The hypopharynx includes the piriform sinuses laterally, post cricoid region inferiorly, and pharyngeal wall posteriorly. The larynx is responsible for maintaining and protecting the airway and allowing phonation. The supraglottis extends from the base of tongue to the apex of the laryngeal ventricle and contains the epiglottis, aryepiglottic folds, false vocal cords, and arytenoid cartilages. The subglottis is the portion of the larynx extending from the inferior surface of the true vocal cord to the inferior margin of the cricoid cartilage, which demarcates the beginning of the trachea. Supra and infrahyoid neck anatomic considerations Excluding the sinonasal cavities, the mucosallined tissues of the upper aerodigestive tract can be divided into the oral cavity, pharynx (oropharynx, nasopharynx, hypopharynx), and larynx. These divisions help us to accurately determine and describe the spread of the superficial mucosabased lesions, namely, squamous cell carcinoma. Suprahyoid neck For submucosal lesions, a more practical approach to anatomy and differential diagnosis is to use a spatial approach in which layers of deep cervical fascia divide the head and neck into multiple fascia enclosed spaces. The suprahyoid neck is the region extending from the skull base to the hyoid bone. It is divided into seven major anatomical spaces by layers of cervical fascia: 1 Pharyngeal mucosal space-essentially the mucosallined tissues of the aerodigestive tract described earlier. Differential diagnosis of suprahyoid masses can be easily formulated if the anatomic components of the each space are known and if one can localize a mass to the correct space. The parapharyngeal space is the central space surrounded by the masticator space anteriorly, carotid space posteriorly, parotid space laterally, and superficial mucosal space medially. Deviation of the fat in the parapharyngeal space can help localize large masses to one of these four spaces. The parapharyngeal space fat is deviated posteromedially by large lesions in masticator space. A mass in the parotid space will deviate it medially, while a carotid space mass will deviate it anteriorly. Submucosal extension of a superficial mucosal mass will deviate the fat laterally. Furthermore, a mass arising either from the pharyngeal mucosal space or the retropharyngeal space displaces the prevertebral muscle complex posteriorly. If the muscle complex is elevated anteriorly off of the spine, then the lesion is suspected to arise from the perivertebral space. Infrahyoid neck the infrahyoid neck is the region of the neck extending from the hyoid bone to the cervicothoracic junction. The infrahyoid region is subdivided into five major spaces by the different layers of deep cervical fascia that are continuous with those in the suprahyoid neck. Laryngeal squamous cell carcinoma the anterior portion of the true vocal cord in the glottis region is the most common site of laryngeal carcinomas. It may involve the contralateral true vocal cord by invading the anterior commissure located anteriorly. Midsagittal images are helpful for demonstrating the relationship between the tumor and the anterior commissure and thus play a major role in disease staging. Carotid space paragangliomas Paragangliomas are benign vascular tumors that arise from the neural crest cells of the sympathetic nervous system. These tumors are named on the location and the nerves of their origin and include glomus jugulare (jugular ganglion of vagus nerve at the skull base), glomus vagale (ganglion of vagus nerve below skull base), and carotid body tumor (carotid body at carotid bifurcation). Schwannomas Schwannomas are encapsulated benign tumors that arise from nerve sheath coverings within the carotid space. They do enhance, but unlike paragangliomas, they are not particularly hypervascular. Metastatic nodal disease Enlarged and pathologicappearing nodes are seen in both metastatic disease and infection and cannot be differentiated on imaging. Imaging findings suggestive of malignancy are irregular margins, heterogeneous signal with invasion of adjacent soft tissue spaces, and associated lymphadenopathy. Primary tumors are commonly of benign nature and often of a neural or vascular origin. Adjacent lesions with secondary invasion into masticator space are often found, especially from the pharynx. The mass is hypointense on the precontrast T1weighted image (a) and slightly hyperintense on the T2weighted image (b). It also demonstrated enhancement on the arterialphase postcontrast T1 image (c) (arrows). Visceral space Laryngocele Laryngocele is defined as an abnormal saccular dilatation of the laryngeal ventricle. On imaging studies, it appears as a sharply defined cystic lesion with enhancing boundaries. Adenomas are hypervascular lesions adjacent to thyroid lobes or rarely in ectopic locations with variable contrast enhancement and early washout. In infection, they are seen as complex heterogeneous masses with internal fluid debris and associated inflammatory changes. It is often used in the follow up of patients with multinodular goiter to evaluate nodule growth and consistency. Certain ultrasonographic features have been identified that may suggest an increased risk for malignancy such as hypoechogenicity, the presence of microcalcifications, increased central blood flow, or irregular borders. However, in the absence of the aforementioned features, malignancy cannot be excluded definitively. The major role of thyroid scintigraphy is to determine the functional status of a suspected autonomously functioning thyroid nodule. Osteomyelitis of vertebra Vertebral osteomyelitis should be considered in all patients experiencing unremitting and/or focal vertebral pain that is not relieved by lying down, particularly if accompanied by fever or paravertebral symptoms indicating a psoas or other paraspinal extension. Radiography should be ordered for all patients with suspected vertebral osteomyelitis. The earliest signs are loss of definition of a vertebral end plate and narrowing of the associated disc space. If radiography is not diagnostic and the patient has pain that is unremitting or if patient is febrile, other imaging should be considered. Cystic hygroma Cystic hygroma is a type of congenital lymphatic malformation most commonly seen in the pediatric age group. It is an endothelial lined cavernous lymphatic space arising from the expansion of embryonic lymph lakes that fails to develop normal lymphatic drainage. They may show variable density/intensity, with a combination of fluid, soft tissue, and fat. This chapter will discuss the role of the different imaging modalities in the evaluation of the musculoskeletal system, the normal appearance of musculoskeletal specific structures, and the critical concepts in the analysis of musculoskeletal examinations. Brief overviews of trauma, arthritis, tumors, and interventional procedures will follow. Imaging modalities radiography Radiographs of biological tissues result in four densities: air, fat, soft tissue, and bone. The variation in soft tissue density between that of water, blood, muscle, and other organs is so small that these cannot be differentiated on a radiograph. Many structures in the extremities are bordered by fat, allowing one to identify normal contours. Radiography is particularly suited to imaging bones for two reasons: the very large difference in density between the bone and soft tissue and their high spatial resolution. Radiographs are the mainstay for the imaging of the arthritides, the initial assessment of bone tumors, the evaluation of orthopedic instrumentation, and, of course, trauma. Due to the relatively low cost of radiographs and wide availability, radiographs serve as the initial diagnostic study for all musculoskeletal complaints. Limitations of radiography include limited ability to evaluate complex threedimensional structures (such as the cervical spine, the sacroiliac joints, and the complex fractures), limited ability to penetrate large volumes of tissue, and quite limited ability to evaluate soft tissue pathology. Routine diagnostic radiographic examinations have at least two (anteroposterior and lateral) and often more projections that are tailored to the body part in question. The tangential patellar view (or "sunrise view") of the knee, the mortise view of the ankle, and the outlet view of the shoulder are examples. By convention, dense structures (such as bone) are bright on radiographs, whereas less dense structures (such as air) are dark. The primary use of fluoroscopy in musculoskeletal radiology is to guide needles for joint injections/aspirations and bone biopsies. Fluoroscopy is often used intraoperatively to guide and/ or evaluate the placement of orthopedic instrumentation. By convention, fluoroscopic images are displayed such that dense structures are dark compared to less dense structures, which are bright-the inverse of the radiographic convention. Different soft tissue types can often be differentiated, such as tendon versus muscle. The difference in density between blood products and simple fluid can also be detected. With intravenous contrast, abscesses can be detected and intramuscular masses can also be detected. Finally, the acquisition of the images is rapid, taking no more than several seconds for a focused examination, such as the shoulder. Crosssectional imaging is particularly important for the evaluation of skeletal trauma, both for identification and characterization. Fractures of the pelvis and cervical spine may be difficult to see on radiographs, and the ability to review axial, coronal, and sagittal crosssectional images is essential to make an accurate diagnosis. Examples include acetabular fractures, tibial plateau fractures, and some ankle fractures. Except in the setting of extremity infection and rare instances of soft tissue tumors, intravenous contrast is not routinely used in musculoskeletal imaging. Metal artifact results in streaks of apparent high or low density due to the interaction between the reconstruction algorithm and the marked disparity in density between metal and adjacent tissue, including the bone. For questions regarding infection or evaluation of tumors, intravenous contrast is used. First, due to its dependence on a uniform magnetic field, anything that distorts the magnetic field will affect the image. Specific details and combinations may differ depending on the body part or clinical question. The vast majority of musculoskeletal examinations are for internal derangements, and routine protocols have been developed for every joint; these protocols do not employ intravenous or intraarticular contrast. For cases involving the administration of intravenous contrast, the routine protocols are often pared down to allow for the additional sequences needed to evaluate for tissue enhancement while still imaging the area in a reasonable amount of time. The high resolution achievable with modern ultrasound equipment allows excellent characterization of tendons, ligaments, and nerves. Achievable resolution is directly proportional to the frequency of the sound wave-high resolutions require the use of high frequencies. Unfortunately, the depth of tissue penetration decreases with increasing frequency. As a result, highresolution ultrasound excels in the evaluation of superficial structures, such as the rotator cuff of the shoulder. Another clinical advantage of ultrasound in comparison to the other modalities discussed here is the ability to perform dynamic evaluation of joints. Stress imaging, which can also be performed with fluoroscopy, can easily be performed with ultrasound without the radiation exposure. The realtime nature of sonography also lends itself well to guidance for percutaneous procedures. The normal soft tissues of the musculoskeletal system have readily identifiable echotextures. Muscle in the short axis has a "starry sky" appearance, tendons and ligaments in the long axis have a fibrillar appearance, and nerves in the long axis have a fascicular appearance. As discussed previously, highresolution imaging is best reserved for superficial structures. The deeper a structure is from the skin surface at a particular frequency, the less signal is received back at the transducer to form images.

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This chest X-ray demonstrates cardiomegaly spasms going to sleep order robaxin online, hilar haziness spasms in throat buy robaxin mastercard, Kerley B lines muscle relaxant apo 10 buy robaxin toronto, upper lobe venous blood engorgement and fluid in the right horizontal fissure muscle relaxant non-prescription generic 500mg robaxin mastercard. Hilar haziness and Kerley B lines (thin linear horizontal pulmonary opacities at the base of the lung periphery) indicate interstitial pulmonary oedema muscle relaxant at walgreens purchase robaxin 500mg amex. The heart rate (if the rhythm is regular) is calculated by counting the number of big squares between two consecutive R waves and dividing into 300 spasmus nutans treatment best 500 mg robaxin. In normal circumstances only the specialized conducting tissues of the heart undergo spontaneous depolarization (automaticity), which initiates an action potential. Thus in the right ventricular leads (V1 and V2) the first deflection is upwards (R wave) as the septal depolarization wave spreads towards those leads. The second deflection is downwards (S wave) as the bigger left ventricle (in which depolarization is spreading away) outweighs the effect of the right ventricle. The opposite pattern is seen in the left ventricular leads (V5 and V6), with an initial downwards deflection (small Q wave reflecting septal depolarization) followed by a large R wave caused by left ventricular depolarization. The R wave in the chest (precordial) leads steadily increases in amplitude from lead V1 to V6 with a corresponding decrease in S wave depth, culminating in a predominantly positive complex in V6. Left ventricular hypertrophy with increased bulk of the left ventricular myocardium. This gives rise to tall R waves (>25 mm) in the left ventricular leads (V5, V6) and/or deep S waves (>30 mm) in the right ventricular leads (V1, V2). Inverted T waves occur in many conditions and, although usually abnormal, they are a non-specific finding. It is the time taken for excitation to pass from the sinus node, through the atrium, atrioventricular node and His-Purkinje system to the ventricle. It is primarily a measure of the time taken for repolarization of the ventricular myocardium, which is dependent on heart rate (shorter at faster heart rates). The cardiac axis refers to the overall direction of the wave of ventricular depolarization in the vertical plane measured from a zero reference point. Left axis deviation occurs due to a block of the anterior bundle of the main left bundle conducting system. Exercise electrocardiography Exercise electrocardiography assesses the cardiac response to exercise, but is used less often than previously because of its low sensitivity. A slow recovery of the heart rate to basal levels has also been reported to be a predictor of mortality. Contraindications include unstable angina, severe hypertrophic cardiomyopathy, severe aortic stenosis and malignant hypertension. Tilt testing Tilt testing is performed to investigate suspected neurocardiogenic (vasovagal) syncope in which patients give a history of repeated episodes of syncope which occur without warning and are followed by a rapid recovery. The patient lies on a swivel motorized table in a flat position with safety straps applied across the chest and legs to hold them in position. M mode, two- and three-dimensional) are used to provide information about cardiac structure and function. Ultrasound pulses are emitted through various body tissues, and reflected waves are detected by the transducer as an echo. The most common reasons for undertaking an echocardiogram are to assess ventricular function in patients with symptoms suggestive of heart failure, or to assess valvular disease. Further refinements of the echocardiogram are Doppler and stress echocardiography. Doppler echocardiography uses the Doppler principle (in this case, the frequency of ultrasonic waves reflected from blood cells is related to their velocity and direction of flow) to identify and assess the severity of valve lesions, estimate cardiac output and assess coronary blood flow. Stress (exercise or pharmacological) echocardiography is used to assess myocardial wall motion as a surrogate for coronary artery perfusion. For those who cannot exercise, pharmacological intervention with dobutamine is used to increase myocardial oxygen demand. A variety of radiotracers can be injected intravenously and these diffuse freely into myocardial tissue or attach to red blood cells. Technetium-99 m is used to label red blood cells and produce images of the left ventricle during systole and diastole. It is increasingly utilized in the investigation of cardiovascular disease to provide both anatomical and functional information. Contraindications are permanent pacemaker or defibrillator, intracerebral clips and significant claustrophobia. Cardiac catheterization A small catheter is passed through a peripheral vein (for study of right-sided heart structures) or artery (for study of left-sided heart structures) into the heart, permitting the securing of blood samples, measurement of intracardiac pressures and determination of cardiac anomalies. Specially designed catheters are then used to selectively engage the left and right coronary arteries, and contrast cine-angiograms are taken in order to define the coronary circulation and identify the presence and severity of any coronary artery disease. A further development is the introduction of stents coated with drugs (sirolimus or paclitaxel) to reduce cellular proliferation and restenosis rates still further. Arrhythmia may cause sudden death, syncope, dizziness, palpitations or no symptoms at all. Tachycardias are more likely to be symptomatic when the arrhythmia is fast and sustained. General principles of management of arrhythmias Patients with adverse symptoms and signs (low cardiac output, chest pain, hypotension, impaired consciousness or severe pulmonary oedema) require urgent treatment of their arrhythmia. Oxygen is given to all patients, intravenous access established and serum electrolyte abnormalities (potassium, magnesium, calcium) are corrected. Sinus arrhythmia Fluctuations of autonomic tone result in phasic changes in the sinus discharge rate. During inspiration, parasympathetic tone falls and the heart rate quickens, and on expiration the heart rate falls. This variation is normal, particularly in children and young adults, and typically results in predictable irregularities of the pulse. Bradycardia Sinus bradycardia Sinus bradycardia is normal during sleep and in well-trained athletes. Patients with persistent symptomatic bradycardia are treated with a permanent cardiac pacemaker. First-line treatment in the acute situation with adverse signs is atropine (500 g intravenously repeated to a maximum of 3 mg, but contraindicated in myasthenia gravis and paralytic ileus). Temporary pacing (transcutaneous, or transvenous if expertise available) is an alternative. Bradycardia is caused by intermittent failure of sinus node depolarization (sinus arrest) or failure of the sinus impulse to propagate through the perinodal tissue to the atria (sinoatrial block). Thromboembolism is common in sinus node dysfunction and patients are anticoagulated unless there is a contraindication. Heart block the common causes of heart block are coronary artery disease, cardiomyopathy and, particularly in elderly people, fibrosis of the conducting tissue. Sinus tachycardia Sinus tachycardia is a physiological response during exercise and excitement. It also occurs with fever, pain, anaemia, heart failure, thyrotoxicosis, acute pulmonary embolism, hypovolaemia and drugs. Atrioventricular junctional tachycardias Tachycardia arises as a result of re-entry circuits in which there are two separate pathways for impulse conduction. This allows a re-entry circuit and an impulse to produce a circus movement tachycardia. These patients are also prone to atrial and occasionally ventricular fibrillation. Symptoms the usual history is of rapid regular palpitations, usually with abrupt onset and sudden termination. Long-term management Radiofrequency ablation of the accessory pathway via a cardiac catheter is successful in about 95% of cases. It also occurs, particularly in a paroxysmal form (stopping spontaneously within 7 days), in younger patients. In some patients, it is an incidental finding; in others, symptoms range from palpitations and fatigue to acute heart failure. Randomized studies in heart failure and in older patients have shown that neither strategy has net benefits compared with the other. Other agents used depend on the presence (use amiodarone) or absence (sotalol, flecainide, propafenone) of underlying heart disease. Catheter ablation techniques such as pulmonary vein isolation are used in patients who do not respond to antiarrhythmic drugs. Longer-term anticoagulation is indicated in underlying rheumatic mitral stenosis or in the presence of a mechanical heart valve. Trial data have shown them to be equally effective and safer as compared to warfarin. However, these agents require dose reduction or avoidance in patients with renal impairment, elderly patients or those with low body weight. Ventricular tachyarrhythmias Ventricular ectopic premature beats (extrasystoles) these are asymptomatic or patients complain of extra beats, missed beats or heavy beats. It is common in patients with heart disease (and in a few individuals with normal hearts). The patient is pulseless and becomes rapidly unconscious, and respiration ceases (cardiac arrest). The causes include congenital (mutations in sodium and potassium-channel genes), electrolyte disturbances (hypokalaemia, hypocalcaemia, hypomagnesaemia) and a variety of drugs. In acquired cases, treatment is that of the underlying cause and intravenous isoprenaline. The patient is unconscious and apnoeic with absent arterial pulses (best felt in the carotid artery in the neck). Irreversible brain damage occurs within 3 minutes if an adequate circulation is not established. Resuscitation is stopped when there is return of spontaneous circulation and a pulse, or further attempts at resuscitation are deemed futile. Prognosis In many patients resuscitation is unsuccessful, particularly in those who collapse out of hospital and are brought into hospital in an arrested state. In patients who are successfully resuscitated, the prognosis is often poor because they have severe underlying heart diseases. It is a common condition, with an estimated annual incidence of 10% in patients over 65 years. The long-term outcome is poor and approximately 50% of patients are dead within 5 years. Aetiology Ischaemic heart disease is the most common cause in the developed world and hypertension is the most common cause in Africa (Table 10. Any factor that increases myocardial work (arrhythmias, anaemia, hyperthyroidism, pregnancy, obesity) may aggravate existing heart failure or initiate failure. Pathophysiology When the heart fails, compensatory mechanisms attempt to maintain cardiac output and peripheral perfusion. However, as heart failure progresses, the mechanisms are overwhelmed and become pathophysiological. Activation of the sympathetic nervous system Activation of the sympathetic nervous system improves ventricular function by increasing heart rate and myocardial contractility. Constriction of venous capacitance vessels redistributes flow centrally, and the increased venous return to the heart (preload) further augments ventricular function via the Starling mechanism. Sympathetic stimulation, however, also leads to arteriolar constriction; this increases the afterload, which eventually reduces cardiac output. Salt and water retention further increases venous pressure and maintains stroke volume by the Starling mechanism. As salt and water retention increases, however, peripheral and pulmonary congestion causes oedema and contributes to dyspnoea.

Imaging modalities Among all the imaging techniques available for brain evaluation choosing the best option for a given clinical situation may be a challenge spasms under breastbone generic robaxin 500 mg with mastercard. From a practical point of view muscle relaxant side effects buy robaxin 500 mg mastercard, conventional radiography is not used except when documenting fractures for medical/legal reasons spasms vhs purchase robaxin 500mg with visa. Ultrasound is useful as the first imaging technique in infants through the still open fontanelles and thin skull bones and also has a role in evaluation of the cervical carotid arteries and intracranial circulation spasms in 7 month old order 500mg robaxin fast delivery. Catheter digital subtraction angiography is performed in acute setting stenosis spasms face purchase line robaxin, occlusions muscle relaxant drugs discount robaxin online mastercard, or vascular lesions. It is also useful in vascular malforma tions, aneurysm, and vascular tumors for defining their architecture and for embolization. In certain clinical conditions, such as tumors or abscesses, iodinated contrast may be administered to highlight the lesions. It is an increasingly used technique for acute stroke and aneurysm diagnosis, characterization, and treatment planning. It relies on the first pass of a bolus of contrast during which the brain is imaged sequentially. It takes advantage of the fact that intra cellular water molecules have a limited movement compared to extracellular ones. Increased Cho indicates increase in cell production or membrane breakdown, which can suggest neoplasia and infec tion or demyelination, respectively. Lactate and lipids are markers of anaerobic metabolism and necrosis, respectively. When an area of the brain is used, its blood flow increases resulting in differences in oxygenation between arterial and venous blood. Reliable localization of motor, visual, auditory, and language areas assists in planning surgery, particularly in tumors or epilepsy. Iodinated contrast agents increase the density of blood inside vessels and vascular structures such as venous sinus so these are hyperdense on postcontrast scans. The midline of the brain should be in the midline of the skull, and both sides of the brain should look very much alike. The sulci pattern should be symmetric, and the interhemispheric fissure should be visualized. The anatomy of the midline brain is complex and the structures are not duplicated, so the principle of symmetry cannot be applied to its interpretation. On sagittal images, there are three areas that must always be studied: the sella and suprasellar regions, the pineal region, and the craniocervical junction. Regarding the sellar region, on coronal sec tions, the pituitary gland is the main structure and rests in a small, midline bony cavity in the sphenoid bone known as sella turcica. The pituitary stalk is a vertically oriented structure, which con nects the pituitary gland to the hypothalamus and is thinner at its bottom and thicker superiorly. Another major structure in the suprasellar cistern is the optic chiasm, an extension of the brain where the optic nerves cross. Anatomically, the hypothalamus forms the lateral walls and floor of the third ventricle. The pineal gland is adjacent to the dorsal midbrain, which covers the aqueduct of Sylvius. The sharp inferior edge of the bony clivus marks the anterior border of the foramen magnum, known as the basion, and its posterior limit known as the opisthion is the cortical margin of the occipital bone. The cerebellar tonsils should project no more than 5 mm below a line drawn bet ween basion and opisthion. The only structures visualized at the foramen magnum level should be the cervical medullary junction and small portion of cerebellar tonsils. Critical observations Mass lesions the term "mass" is used to mean a spaceoccupying structure. Because the skull is rigid, a mass lesion results on mass effect upon the brain and displaces the normal cerebral structures away from it. The midline structures may be shifted contralateral to a mass, the sulci adjacent maybe effaced, and the ipsilateral ventricles compressed. Conversely, atrophy is recognized by widening of the ipsilateral sulci or enlargement of the ventricles. Epidural hematomas are usually arterial in origin and often result from a skull fracture that disrupts the middle meningeal artery. Stroke the management of acute ischemic stroke remains challenging due to the limited time window in which the diagnosis has to be made and therapy administered. Ischemic lesions involving a single hemisphere are likely to be caused by a lesion within the carotid circulation ipsilateral to the lesion. However, if those lesions affect both hemispheres, they may represent border zone infarcts resulting from global hypoperfusion or be a result of cardiac or other proximal sources of emboli. Cerebral venous thrombosis and venous infarct Cerebral venous thrombosis is an important cause of stroke especially in children and young adults. Filling defects should not be confused with Pacchionian bodies (arachnoid granulations), which can be seen in essentially all dural sinuses and are espe cially common in the superior sagittal and transverse sinuses. Venous infarctions have a nonarterial distribution in the white matter and/or cortex and are often hemorrhagic. Based on its underlying mechanisms, hydrocephalus can be classified into communicating and noncommunicating (obstructive). However, most these patients will not show an acute structural brain lesion, the encephalopathy is instead due to systemic meta bolic abnormalities. When performed in unconscious patients with severe head injury, the craniocervical junction should be included. Subgaleal hematoma is the most common manifestation of scalp injury and is seen as a soft tissue swelling of the scalp located beneath the subcutaneous fibrofatty tissue superficial to the tempo ralis muscle and skull. Isolated linear skull fractures do not require treatment, while surgical management is usually indicated for depressed and compound skull fractures. Depressed fractures are fre quently associated with an underlying brain contusion. Intracranial air (pneumocephalus) may be an indirect sign of fracture particularly one involving the skull base. It may lead to hydrocephalus by obstruction at the level of the aqueduct or arachnoid villi. Illdefined areas of decreased attenuation may also be seen in nonhemorrhagic lesions. Initially, they appear followed by development of surrounding edema, before gradually fading away leaving behind more or less obvious area of atrophy. Occasionally, intraparenchymal hemorrhages not associated with contusions are present, and they represent shearinduced hemor rhage from rupture of small intraparenchymal blood vessels and are usually located in the frontotemporal white matter. These lesions can also present late secondary to delayed hemorrhage, which is a cause of clinical deterioration during the first week after head trauma. It is seen as multiple petechial hemorrhages affecting the basal ganglia and thalamus and is probably due to shearing of tiny perforating arteries. Other traumatic vascular injuries include arterial dissections or occlusions, pseudoaneurysm formation, and acquired arteriovenous or dural fistulas. Secondary brain injury Diffuse cerebral swelling is a common secondary brain injury, usually resulting from increase in tissue fluid content (edema) secondary to hypoxia that leads to generalize mass effect with effacement of sulci and basal cisterns, compression of the ventricles, and loss of gray/white matter differentiation. The cerebellum and brainstem are usually spared and may appear hyperdense relative to the cerebral hemispheres. Additionally, mass effect from cerebral swelling or hematoma can also cause hydrocephalus by compression. Posttraumatic ischemia or infarction can result from raised intracranial pressure, embolization from arterial dissection, or direct mass effect on the cerebral vasculature from brain herniation. Secondary brainstem injury includes infarction, compression usually due to uncal herniation, and hemorrhage, which is known as Duret hemorrhage and is a midline hematoma in the rostral pons and midbrain seen in descending transtentorial herniation. Vascular lesions Stroke is a clinical symptom that is caused by either brain infarction (75%) or hemorrhage (25%) and must be distinguished from other conditions causing abrupt neurologic deficits such as tumors. Infarction is a permanent injury that occurs when tissue perfu sion decreases long enough to cause necrosis, typically due to occlu sion a feeding artery. It may serve as a "warning sign" as 10% of patients will go to develop infarctions in the first 90 days after it. Ischemic strokes can be divided according to territory affected, and mechanism, namely embolism (from the heart, atherosclerotic from aortic arch or carotid arteries, and fat or air embolism) and thrombosis. Thrombi are formed at sites abnormal vascular endo thelium typically over an area of atherosclerotic plaque or ulcers most commonly at the carotid artery bifurcation in the neck. Smallvessel thrombi frequently occur in diseased perforator ves sels causing lacunar infarcts. There is overlap between the throm botic and embolic groups since the majority of emboli begin as thrombi somewhere proximal in the cardiovascular tree (hence the practical term "thromboembolic disease"). Vasculitis, vasospasm, coagulopathies, global hypoperfusion, and venous thrombosis account for 5% of acute strokes but are important to recognize due differing treatments and prognosis. This protocol changes clinical outcome by increasing the number of patients adequately selected for thrombolysis. In the subacute phase of ischemic stroke, edema leads to mass effect ranging from slight sulcal effacement to marked midline shift with brain herniation, depending on the size and location of infarct. Infarcts with volumes over 100 ml are considered "malignant" as they result in marked mass effect that generally leads to death. Reperfusion into infarcted tissues may secondarily lead to gross or microscopic hemorrhages seen in up to 50% of infarcts. The peak time for hemorrhagic transformation is at about 72 h postinfarc tion, and it is usually seen as a serpiginous area of petechial blood following the gyral contours of the infarcted cortex. More extensive hemorrhagic transformation may lead to the formation of a gross hematoma. These hematomas tend to occur earlier and are com monly associated with clinical deterioration and poor outcomes. The watershed or border zone regions are areas perfused by terminal branches of two adjacent arterial territories. When flow in one or both of parent vessels falls below a critical level, the brain in the watershed zone is first to infarct. Unilateral watershed infarcts may be seen in internal carotid occlusion or stenosis, while bilateral watershed infarcts occur in global hypoperfusion. Cerebral venous infarction usually results from thrombosis of cortical veins, while occlusion of isolated dural venous sinuses results in symptoms of intracranial hypertension. Any dural sinus, deep cerebral vein, or cortical vein may be affected in isolation or combination. Venous thromboses usually occur in younger patients presenting with headache, sudden focal deficits, and seizures. Predisposing factors include hypercoagulable states, pregnancy, infection (spread from contiguous scalp, face, middle era, or sinus), dehydration, meningitis, trauma, and direct invasion by tumor. As blood becomes older and the globin molecule breaks down, the hematoma loses its hyperdense appearance, beginning at the periphery and working centrally. Hematomas in the putamen, thalamus, medial cerebellum, and pons suggest hypertension, while a hemispheric hematoma, espe cially in patients older than 65 years, suggests amyloid angiopathy. The nonglial cell tumors are a large heterogeneous group of tumors of which meningioma is most common. Neoplastic processes (benign/malignant) Specific tumors occur under the age of 2 years and include mostly choroid plexus papillomas, anaplastic astrocytomas, medulloblas toma, and teratomas. In the first decade of life, medulloblastomas, astrocytomas, ependymomas, craniopharyngiomas, and gliomas are common, while metastases are rare. At this age, the most fre quent metastases are from neuroblastoma and affect the skull. In some cases, the distinction between intra and extraaxial tumors is difficult to establish. In the region of the cerebellopontine angle, 90% of extraaxial tumors are schwannomas. Meningiomas are located any where where meninges are found and in some places where only rest cells are presumed to be located (such as the carotid artery and jugular vein sheath). Common locations for meningioma are parasagittal, convexities, sphenoid ridge, olfactory groove, planum sphenoidale, and juxtasellar. Primary brain tumors are typically single; nevertheless, some brain tumors like lymphoma, multicentric glioblastoma, and gliomatosis cerebri can be multifocal. An important consideration when assessing a tumor is its mass effect on the surrounding structures. Primary brain tumors are derived from brain cells and often have less mass effect for their size than would be expected, due to their infiltrative growth. Brain imaging 111 Conversely, metastases and extraaxial tumors like meningiomas or schwannomas have significant mass effect. The ability of tumors to cross the midline also limits the differential diagnosis. Radiation necrosis (a complication of radiotherapy or radiosurgery) may have similar imaging fea tures as recurrent tumor and also sometimes cross the midline.