The ventricular system of the brain is made up of four ventricles namely; two lateral and a third and forth ventricle. The ventricles are the site of the development of the cerebrospinal fluid. The left and right lateral ventricles are located in each of the brain’s hemispheres. The roof of the lateral ventricles are made up of the fibres of the corpus callosum. This is the structure that would be compressed by the a tumour on the roof of the lateral ventricles.

The lateral geniculate nucleus (LGN) of the thalamus is the primary processor of visual information in the central nervous system. The LGN receives information directly from the retina and sends projections directly to the primary visual cortex. The LGN likely helps the visual system focus its attention on the most important information.

Answer: Measurement of faecal calprotectin

Based on Rome criteria, this patient has Irritable Bowel Syndrome (IBS). Irritable bowel syndrome (IBS) is a group of symptoms—including abdominal pain and changes in the pattern of bowel movements without any evidence of underlying damage. These symptoms occur over a long time, often years. It has been classified into four main types depending on whether diarrhoea is common or constipation is common, or both are common, or neither occurs very often (IBS-D, IBS-C, IBS-M, or IBS-U respectively). IBS negatively affects quality of life and may result in missed school or work. Disorders such as anxiety, major depression, and chronic fatigue syndrome are common among people with IBS.

The recommendations for physicians are to minimize the use of medical investigations. Rome criteria are usually used. They allow the diagnosis to be based only on symptoms, but no criteria based solely on symptoms is sufficiently accurate to diagnose IBS. Worrisome features include onset at greater than 50 years of age, weight loss, blood in the stool, iron-deficiency anaemia, or a family history of colon cancer, celiac disease, or inflammatory bowel disease. The criteria for selecting tests and investigations also depends on the level of available medical resources.

Rome criteria
The Rome IV criteria includes recurrent abdominal pain, on average, at least 1 day/week in the last 3 months, associated with two or more of the following criteria:

Related to defecation
Associated with a change in frequency of stool
Associated with a change in form (appearance) of stool.
Physicians may choose to use one of these guidelines or may simply choose to rely on their own anecdotal experience with past patients. The algorithm may include additional tests to guard against misdiagnosis of other diseases as IBS. Such red flag symptoms may include weight loss, gastrointestinal bleeding, anaemia, or nocturnal symptoms. However, red flag conditions may not always contribute to accuracy in diagnosis; for instance, as many as 31% of people with IBS have blood in their stool, many possibly from hemorrhoidal bleeding.

The diagnostic algorithm identifies a name that can be applied to the person’s condition based on the combination of symptoms of diarrhoea, abdominal pain, and constipation. For example, the statement 50% of returning travellers had developed functional diarrhoea while 25% had developed IBS would mean half the travellers had diarrhoea while a quarter had diarrhoea with abdominal pain. While some researchers believe this categorization system will help physicians understand IBS, others have questioned the value of the system and suggested all people with IBS have the same underlying disease but with different symptoms

The main diseases that cause an increased excretion of faecal calprotectin are inflammatory bowel diseases, coeliac disease, infectious colitis, necrotizing enterocolitis, intestinal cystic fibrosis and colorectal cancer.

Although a relatively new test, faecal calprotectin is regularly used as indicator for inflammatory bowel diseases (IBD) during treatment and as diagnostic marker. IBD are a group of conditions that cause a pathological inflammation of the bowel wall. Crohn’s disease and ulcerative colitis are the principal types of inflammatory bowel disease. Inflammatory processes result in an influx of neutrophils into the bowel lumen. Since calprotectin comprises as much as 60% of the soluble protein content of the cytosol of neutrophils, it can serve as a marker for the level of intestinal inflammation. Measurement of faecal calprotectin has been shown to be strongly correlated with 111-indium-labelled leucocytes – considered the gold standard measurement of intestinal inflammation. Levels of faecal calprotectin are usually normal in patients with irritable bowel syndrome (IBS). In untreated coeliac disease, concentration levels of faecal calprotectin correlate with the degree of intestinal mucosal lesion and normalize with a gluten-free diet.

Faecal calprotectin is measured using immunochemical techniques such as ELISA or immunochromatographic assays. The antibodies used in these assays target specific epitopes of the calprotectin molecule.

Gallbladder ultrasonography should be considered if the patient has recurrent dyspepsia or characteristic postprandial pain.

Abdominal computed tomography (CT) scanning is appropriate to screen for tumours, obstruction, and pancreatic disease if these are diagnostic possibilities.

CT and magnetic resonance (MR) enterography or wireless capsule endoscopy are employed if red flags exist to suggest enteritis (small bowel inflammation) or a tumour.

Colonoscopy is appropriate if alarm symptoms are present and in patients who otherwise qualify for screening colonoscopy.

The oxygen-haemoglobin dissociation curve plots saturated haemoglobin against the oxygen tension and is usually a sigmoid plot. Each molecule of haemoglobin can bind to four molecules of oxygen reversibly. Factors that can influence the binding include: pH, concentration of 2,3-diphosphoglycerate (2,3-DPG), temperature, type of haemoglobin molecules, and presence of toxins, especially carbon monoxide. Shape of the curve is due to interaction of bound oxygen molecules with the incoming molecules. The binding of first molecule is difficult, with easier binding of the second and third molecule and increase in difficulty with the fourth molecule – partly as a result of crowding and partly as a natural tendency of oxygen to dissociate. Left shift of curve indicates haemoglobin’s increased affinity for oxygen (seen at lungs). Right shift indicates decreased affinity and is seen with
increase in body temperature, hydrogen ions, 2,3-diphosphoglycerate (DPG), carbon dioxide concentration and exercise. Under normal resting conditions in a healthy individual, the normal position of the curve is at a pH of 7.4. A shift in the position of the curve with a change in pH is called the Bohr effect. Left shift occurs in acute alkalosis, decrease in p(CO2), decrease in temperature and decrease in 2,3-DPG. The fetal haemoglobin curve is to the left of the adult haemoglobin to allow for oxygen diffusion across the placenta. The curve for myoglobin is even further to the left. Carbon monoxide has a much higher affinity for haemoglobin than oxygen does. Thus, carbon monoxide poisoning leads to hypoxia.

The short gastric arteries branch from the splenic artery near the splenic hilum to travel back in the gastrosplenic ligament to supply the fundus of the stomach. Therefore, these may be injured in this case.
The splenic artery courses deep to the stomach to reach the hilum of the spleen. It doesn’t travel in the gastrosplenic ligament although it does give off branches that do.
The middle colic artery is a branch of the superior mesenteric artery that supplies the transverse colon.
Gastroepiploic artery is the largest branch of the splenic artery that courses between the layers of the greater omentum to anastomose with the right gastroepiploic.
Left gastric artery, a branch of the coeliac trunk. It supplies the left half of the lesser curvature.

High-voltage electrical burns are associated with rhabdomyolysis. Acute tubular necrosis may also occur.

Electrical burns occur following exposure to electrical current. Full-thickness burns are third-degree burns. With these types of burns, the epidermal and dermal layers of skin are destroyed, and the damage may even penetrate the layer of fat beneath the skin.

Following the burn, there is a local response with progressive tissue loss and release of inflammatory cytokines. Systemically, there are cardiovascular effects resulting from fluid loss and sequestration of fluid into the third space. There is a marked catabolic response as well. Immunosuppression is common with large burns, and bacterial translocation from the gut lumen is a recognised event. Sepsis is a common cause of death following major burns.

After the initial management and depth assessment of the burn, the patient is transferred to burn centre if:
1. Needs burn shock resuscitation
2. Face/hands/genitals affected
3. Deep partial-thickness or full-thickness burns
4. Significant electrical/chemical burns

Management options include:
1. The initial aim is to stop the burning process and resuscitate the patient. Adults with burns greater than 15% of total body surface area require burn fluid resuscitation. Fluids administration is calculated using the Parkland formula. Half of the fluid is administered in the first eight hours. A urinary catheter should be inserted and analgesics should be started.

2. Conservative management is appropriate for superficial burns and mixed superficial burns that will heal in two weeks. More complex burns may require excision and skin grafting. Excision and primary closure is not generally practised as there is a high risk of infection.

3. Circumferential full-thickness burns affecting a limb or severe torso burns impeding respiration may require escharotomy to divide the burnt tissue.

4. There is no evidence to support the use of antimicrobial prophylaxis or topical antibiotics in burn patients.

The clinical symptoms of Superior Orbital Fissure Syndrome can be explained by the nerve involvement on an anatomic basis.
External ophthalmoplegia is secondary to impairment of the oculomotor, trochlear, and abducens nerves.
Ptosis develops because of lost tension and function of the levator palpebrae superior muscle involving the superior branch of the oculomotor nerve, and loss of tone in Muller’s muscle involving the sympathetic fibre arising from the cavernous sinus.
Proptosis is caused by a decreased tension of the extraocular muscles, which normally are globe retractors, thereby allowing forward movement of the globe.
The fixed dilated pupil with loss of accommodation arises from disruption of the parasympathetic fibres coursing with the oculomotor nerve.
Compromise of the lacrimal and frontal nerves of the ophthalmic branches of the trigeminal nerve results in anaesthesia of the forehead and upper eyelid, lacrimal hyposecretion, and possibly in retro-orbital pain and neuralgia along the path of the nerve.
Because of the disruption of the sensory nasociliary nerve, there may be anaesthesia of the cornea and the bridge of the nose with loss of the corneal reflex. When the disruption is partial, the corneal reflex remains intact.
If the optic nerve is also involved including the above-mentioned symptoms, it is known as the orbital apex syndrome.

Gaining venous access in small children is challenging most of the times especially in cases of trauma. Therefore, intraosseous infusions should be preferred in this setting. Broviac lines are long-term IV access systems with narrow lumens and, hence, would be unsuitable.

Intraosseous access is typically undertaken at the anteromedial aspect of the proximal tibia and provides access to the marrow cavity and circulatory system. Although traditionally preferred in paediatric practice, it may be used in adults as well, and a wide range of fluids can be infused using this approach.

Codman’s triangle is the triangular area of new subperiosteal bone that is created when a lesion, often a tumour, raises the periosteum away from the bone. The main causes for this sign are osteosarcoma, Ewing’s sarcoma, eumycetoma, and a subperiosteal abscess.

Supination is the rotation of the forearm so that the palm of the hand faces anteriorly. This is performed by the biceps brachii and supinator of the extensor muscles of the thumb. The opposite action of moving the palm from an anterior-facing position to a posterior-facing position is called pronation. Pronation is performed by the pronator teres and pronator quadratus.

Branches that stem from the abdominal aorta can be divided into three: the visceral branches, parietal branches and terminal branches. Of the visceral branches, the suprarenal, renal, testicular and ovarian arteries are paired while the coeliac artery and superior and inferior mesenteric arteries are unpaired. Of the parietal branches the inferior phrenic and lumbar arteries are paired while the middle sacral artery is unpaired. The terminal branches i.e. the common iliac arteries are paired.

Thirst is the basic need or instinct to drink. It arises from a lack of fluids and/or an increase in the concentration of certain osmolites such as salt. If the water volume of the body falls below a certain threshold or the osmolite concentration becomes too high, the brain signals thirst. Excessive thirst, known as polydipsia, along with excessive urination, known as polyuria, may be an indication of diabetes. Angiotensin II is a hormone that is a powerful dipsogen (i.e. it stimulates thirst) that acts via the subfornical organ. It increases secretion of ADH in the posterior pituitary and secretion of ACTH in the anterior pituitary.

Hyperacute rejection occurs almost immediately following organ implantation and necessitates immediate explant of the organ. Hyperacute rejection is uncommon with pre-transplantation cross-matches and screening. Hyperacute rejection (HAR) of the kidney was first recognized 20 years ago in cases of donor-recipient incompatibility for the major blood group and tissue antigen systems. Classic pathological changes described include early accumulation of PMNs in glomeruli and peritubular capillaries, progressive glomerular thrombosis, tubular necrosis, and eventual cortical necrosis. Reaction of host humoral antibodies with antigens on donor cells serves as one trigger of the clotting mechanism, which then proceeds in a nonspecific fashion.

Antigen systems other than the ABO groups that contribute to HAR reactions are leukocyte antigens, endothelial and monocyte antigens, and B cell antigens. It is also documented that glomerular thrombosis identical to HAR may occur secondary to endothelial damage after pulsatile perfusion. However, in such cases no specific deposition of immunoglobulins and complement is detected.

The inferior rectus muscle is a muscle in the orbit. As with most of the muscles of the orbit, it is innervated by the inferior division of oculomotor nerve (Cranial Nerve III). It depresses, adducts, and helps laterally rotate the eye.

Respiratory acidosis occurs due to alveolar hypoventilation which leads to increased arterial carbon dioxide concentration (p(CO2)). This in turn decreases the HCO3 –/p(CO2) and decreases pH. Respiratory acidosis can be acute or chronic. In acute respiratory acidosis, the p(CO2) is raised above the upper limit of normal (over 45 mm Hg) with low pH. However, in chronic cases, the raised p(CO2) is accompanied with a normal or near-normal pH due to renal compensation and an increased serum bicarbonate (HCO3 – > 30 mmHg). The given problem represents acute respiratory acidosis and thus, will show a increase in arterial p(CO2) and decrease in pH.

Catheter-directed thrombolysis (CDT) is recommended as the next step of management for patients with proximal upper-extremity deep vein thrombosis (UEDVT) of recent onset or severe symptoms.

Primary UEDVT is less common than secondary forms. The most common primary form is effort-related thrombosis, also called Paget-Schroetter syndrome. It usually occurs in otherwise healthy young men who report, before the onset of thrombosis, vigorous arm exercise such as lifting weights, playing badminton, pitching a baseball, or performing repetitive overhead activities, such as painting or car repair. Most patients with effort-related UEDVT have an underlying venous thoracic outlet syndrome (VTOS). Secondary causes of UEDVT include central line insertion, malignancy, or pacemakers.

Patients with UEDVT typically present with heaviness, discomfort, pain, paraesthesia, and swelling of the affected arm. Physical examination may reveal pitting oedema, redness, or cyanosis of the involved extremity; visible collateral veins at the shoulder or upper arm; and fever.

Diagnosis is made by:
1. FBC: platelet function
2. Coagulation profile
3. Liver function tests
4. Duplex scan: investigation of choice
5. D-dimer testing
6. CT scan: for VTOS

Treatment options for primary UEDVT are as follows:
1. Anticoagulation therapy should be undertaken with a once-daily regimen of LMWH or fondaparinux for at least five days, followed by vitamin K antagonists for at least three months. Unfractionated heparin instead of LMWH is recommended for patients with renal failure or for those treated with CDT.

2. Early thrombus removal and restoration of venous patency should be done immediately after starting the patient on heparin. Catheter-based therapy is recommended for patients with proximal UEDVT of recent onset and severe symptoms, low risk for bleeding complications, and good functional status.

Answer: Excision biopsy of a lymph node

Hodgkin lymphoma is an uncommon cancer that develops in the lymphatic system, which is a network of vessels and glands spread throughout your body. In Hodgkin lymphoma, B-lymphocytes (a particular type of lymphocyte) start to multiply in an abnormal way and begin to collect in certain parts of the lymphatic system, such as the lymph nodes (glands). The affected lymphocytes lose their infection-fighting properties, making you more vulnerable to infection. The most common symptom of Hodgkin lymphoma is a painless swelling in a lymph node, usually in the neck, armpit or groin.
A histologic diagnosis of Hodgkin lymphoma is always required. An excisional lymph node biopsy is recommended because the lymph node architecture is important for histologic classification.

Features of Hodgkin lymphoma include the following:

Asymptomatic lymphadenopathy may be present (above the diaphragm in 80% of patients)

Constitutional symptoms (unexplained weight loss [>10% of total body weight] within the past 6 months, unexplained fever >38º C, or drenching night sweats) are present in 40% of patients; collectively, these are known as B symptoms

Intermittent fever is observed in approximately 35% of cases; infrequently, the classic Pel-Ebstein fever is observed (high fever for 1-2 week, followed by an afebrile period of 1-2 week)

Chest pain, cough, shortness of breath, or a combination of those may be present due to a large mediastinal mass or lung involvement; rarely, haemoptysis occurs

Pruritus may be present

Pain at sites of nodal disease, precipitated by drinking alcohol, occurs in fewer than 10% of patients but is specific for Hodgkin lymphoma

Back or bone pain may rarely occur

A family history is also helpful; in particular, nodular sclerosis Hodgkin lymphoma (NSHL) has a strong genetic component and has often previously been diagnosed in the family.

Lacunar stroke or lacunar infarct (LACI) is the most common type of ischaemic stroke, and results from the occlusion of small penetrating arteries that provide blood to the brain’s deep structures.

Types:
Pure motor stroke/hemiparesis – It is marked by hemiparesis or hemiplegia that typically affects the face, arm, or leg of the side of the body opposite the location of the infarct. Dysarthria, dysphagia, and transient sensory symptoms may also be present.

Ataxic hemiparesis – It displays a combination of cerebellar and motor symptoms, including weakness and clumsiness, on the ipsilateral side of the body. It usually affects the leg more than it does the arm; hence, it is known also as homolateral ataxia and crural paresis. The onset of symptoms is often over hours or days.

Dysarthria/clumsy hand – The main symptoms are dysarthria and clumsiness (i.e., weakness) of the hand, which often are most prominent when the patient is writing.

Pure sensory stroke – Marked by numbness (loss of sensation) on one side of the body; can later develop tingling, pain, burning, or another unpleasant sensation on one side of the body.

Mixed sensorimotor stroke – This lacunar syndrome involves hemiparesis or hemiplegia (weakness) with sensory impairment in the contralateral side.

The peroneus brevis is supplied by the fourth and fifth lumbar and first sacral nerves through the superficial peroneal nerve which is one of the two terminal branches of the common peroneal nerve. The common peroneal nerve winds around the neck of the fibula and can be injured in cases of fractured neck of fibula.

The musculoskeletal nerve supplies the muscles of the anterior compartment of the arm including the coracobrachialis, biceps brachii and the greater part of the brachialis. This nerve derives its fibres from the fifth, sixth and seventh cervical nerves and arises from the lateral cord of the brachial plexus. It also provides a branch to the elbow joint.

Idiopathic thrombocytopenic purpura (ITP) is a disease caused due to development of an antibody against a platelet antigen (autoantibody). In childhood disease, the autoantibody gets triggered by binding of viral antigen to the megakaryocytes. Presentation includes unexplained thrombocytopenia, petechiae and bleeding from mucosal surfaces. The spleen usually does not enlarge in size. However, splenomegaly can occur due to coexisting viral infection. Marrow examination reveals normal or increased number of megakaryocytes. Diagnosis is by exclusion of other thrombocytopenic disorders.

Duct ectasia is the cause of nipple discharge, with different percentages recorded in different articles (>10%, >30% and >50%). Duct ectasia differs from cystic disease since it is an inflammatory process, usually affecting the ducts below the nipple. It develops gradually, either through the ductal system or the breast lobes. The acute inflammation may be caused by epithelial rupture and diffusion of the contents into the fibrous duct-wall and the underlying structures. These contents consist of neutral fat and lipid crystals that are typical of duct ectasia. The chronic granulation-type reaction may develop foreign body-like giant cells and a multiform inflammatory cell population. Since the whole process in duct ectasia is long in duration, plasma cells are sometimes dominant in the inflammatory infiltrations. Other findings in duct ectasia include the following:
-Serous or green-white nipple discharge in 20% of cases;
-Nipple inversion that leads to fibrosis and development of ring or tubular calcification (this finding is typical in the mammogram and especially when the disease is in its advanced stages);
-Apocrine metaplasia with or without epithelial hyperplasia. The epithelial layer consists of widened atrophic cells.
The condition may be managed symptomatically and/or with antibiotics, but in persistent or recurrent cases it is managed with surgical excision of the ducts below the nipple. A focused excision is preferred to a complete subareolar excision since the later technique is associated with higher rates of seroma formation, nipple numbness and nipple inversion. The Hadfield’s procedure (major duct excision) is an option.

The flexor retinaculum is immediately posterior to the medial malleolus. The structures that pass under the flexor retinaculum from anterior to posterior are: tendon of the tibialis posterior, flexor digitorum longus, posterior tibial artery (and vein), tibial nerve and tendon of flexor hallucis longus. The tibial nerve is the only one which lies behind the flexor retinaculum.

The blood supply to the hip joint is from two main arteries, the medial circumflex femoral and lateral circumflex femoral arteries. These are branches of the deep artery of the thigh, which itself is a branch of the femoral artery. There is contribution of blood supply from the inferior gluteals, foveal and obturator arteries.

The ilioinguinal nerve arises together with the iliohypogastric nerve from the first lumbar nerve to emerge from the lateral border of the psoas major muscle just below the iliohypogastric and passing obliquely across the quadratus lumborum and iliacus muscles. It perforates the transversus abdominis, near the anterior part of the iliac crest and communicates with the iliohypogastric nerve between the internal oblique and the transversus. It then pierces the internal oblique to distribute filaments to it and accompanying the spermatic cord through the subcutaneous inguinal ring, is distributed to the skin of the upper and medial parts of the thigh, the skin over the root of the penis and the upper part of the scrotum in man and to the skin covering the mons pubis and labium majus in the woman. As the ilioinguinal nerve runs through the inguinal canal, it could easily be compressed by a hernial sac.
The femoral branch of genitofemoral nerve provides sensory innervation of the upper medial thigh.
The femoral nerve innervates the compartment of the thigh and also has some cutaneous sensory branches to the thigh.
The iliohypogastric nerve innervates the skin of the lower abdominal wall, upper hip and upper thigh. The subcostal nerve innervates the skin of the anterolateral abdominal wall and the anterior scrotal nerve is a terminal branch of the ilioinguinal nerve.

Astrocytomas are primary intracranial tumours derived from astrocyte cells of the brain. They can arise in the cerebral hemispheres, in the posterior fossa, in the optic nerve and, rarely, in the spinal cord. These tumours express glial fibrillary acidic protein (GFAP). In almost half of cases, the first symptom of an astrocytoma is the onset of a focal or generalised seizure. Between 60% and 75% of patients will have recurrent seizures during the course of their illness. Secondary clinical sequelae may be caused by elevated intracranial pressure (ICP) cause by the direct mass effect, increased blood volume, or increased cerebrospinal fluid (CSF) volume. CT will usually show distortion of the third and lateral ventricles, with displacement of the anterior and middle cerebral arteries. Histological diagnosis with tissue biopsy will normally reveal an infiltrative character suggestive of the slow growing nature of the tumour.

Alveolar ventilation = respiratory rate × (tidal volume − anatomical dead space volume). Increase in respiratory rate simply causes movement of air in the anatomical dead space, with no contribution to the alveolar ventilation. By use of a shorter snorkel, the effective anatomical dead space will decrease and will cause a maximum rise in alveolar ventilation along with doubling of tidal volume.

Secondary hyperaldosteronism in hypertension is either due to primary renin overproduction by the kidneys or renin overproduction secondary to decreased renal blood flow. The main stimulus for aldosterone release are adrenocorticotrophic hormone (ACTH), angiotensin II and high plasma K+ levels. Low plasma Na+ might also stimulate the adrenal cortex. Fluid overload will reduce aldosterone secretion. Atrial natriuretic peptide is secreted under conditions of expanded extracellular volume and will not lead to aldosterone secretion.

The pectineus is supplied by the second, third and fourth lumbar nerves through the femoral nerve and by the third lumbar through the accessory obturator when it exists. The anterior surface of the thigh receives its innervation from the femoral nerve as well, thus this is the nerve most likely to be injured

The development of the kidney proceeds through a series of successive phases, each marked by the development of a more advanced kidney: the pronephros, mesonephros, and metanephros. The development of the pronephric duct proceeds in a cranial-to-caudal direction. As it elongates caudally, the pronephric duct induces nearby intermediate mesoderm in the thoracolumbar area to become epithelial tubules called mesonephric tubules. Each mesonephric tubule receives a blood supply from a branch of the aorta, ending in a capillary tuft analogous to the glomerulus of the definitive nephron. The mesonephric tubule forms a capsule around the capillary tuft, allowing for filtration of blood. This filtrate flows through the mesonephric tubule and is drained into the continuation of the pronephric duct, now called the mesonephric duct or Wolffian duct. The nephrotomes of the pronephros degenerate while the mesonephric duct extends towards the most caudal end of the embryo, ultimately attaching to the cloaca.