Alzheimer’s disease, the leading cause of dementia, is characterized by the presence of beta-amyloid plaques and neurofibrillary tangles in the brain. These plaques are formed due to an excessive buildup of amyloid, which can be caused by either overproduction or impaired clearance of beta-amyloid. The accumulation of amyloid plaques leads to inflammation in the surrounding brain tissue, resulting in damage to neurons. Additionally, the abnormal phosphorylation of tau protein causes it to aggregate into neurofibrillary tangles within neurons. It is important to note that Lewy bodies, composed mainly of alpha-synuclein, are associated with diseases like Parkinson’s disease and dementia with Lewy bodies. Autoimmune diseases often involve the activation of autoreactive T-cells.

Further Reading:

Dementia is a progressive and irreversible clinical syndrome characterized by cognitive and behavioral symptoms. These symptoms include memory loss, impaired reasoning and communication, personality changes, and reduced ability to carry out daily activities. The decline in cognition affects multiple domains of intellectual functioning and is not solely due to normal aging.

To diagnose dementia, a person must have impairment in at least two cognitive domains that significantly impact their daily activities. This impairment cannot be explained by delirium or other major psychiatric disorders. Early-onset dementia refers to dementia that develops before the age of 65.

The most common cause of dementia is Alzheimer’s disease, accounting for 50-75% of cases. Other causes include vascular dementia, dementia with Lewy bodies, and frontotemporal dementia. Less common causes include Parkinson’s disease dementia, Huntington’s disease, prion disease, and metabolic and endocrine disorders.

There are several risk factors for dementia, including age, mild cognitive impairment, genetic predisposition, excess alcohol intake, head injury, depression, learning difficulties, diabetes, obesity, hypertension, smoking, Parkinson’s disease, low social engagement, low physical activity, low educational attainment, hearing impairment, and air pollution.

Assessment of dementia involves taking a history from the patient and ideally a family member or close friend. The person’s current level of cognition and functional capabilities should be compared to their baseline level. Physical examination, blood tests, and cognitive assessment tools can also aid in the diagnosis.

Differential diagnosis for dementia includes normal age-related memory changes, mild cognitive impairment, depression, delirium, vitamin deficiencies, hypothyroidism, adverse drug effects, normal pressure hydrocephalus, and sensory deficits.

Management of dementia involves a multi-disciplinary approach that includes non-pharmacological and pharmacological measures. Non-pharmacological interventions may include driving assessment, modifiable risk factor management, and non-pharmacological therapies to promote cognition and independence. Drug treatments for dementia should be initiated by specialists and may include acetylcholinesterase inhibitors, memantine, and antipsychotics in certain cases.

In summary, dementia is a progressive and irreversible syndrome characterized by cognitive and behavioral symptoms. It has various causes and risk factors, and its management involves a multi-disciplinary approach.

Post myocardial infarction ventricular septal defect (VSD) is a rare but serious complication that occurs when the cardiac wall ruptures. It typically develops 2-3 days after a heart attack, and if left untreated, 85% of patients will die within two months. The murmur associated with VSD is a continuous sound throughout systole, and it is loudest at the lower left sternal edge. A palpable vibration, known as a thrill, is often felt along with the murmur.

Dressler’s syndrome, on the other hand, is a type of pericarditis that occurs 2-10 weeks after a heart attack or cardiac surgery. It is characterized by sharp chest pain that is relieved by sitting forwards. Other signs of Dressler’s syndrome include a rubbing sound heard when listening to the heart, pulsus paradoxus (an abnormal drop in blood pressure during inspiration), and signs of right ventricular failure.

Mitral regurgitation also causes a continuous murmur throughout systole, but it is best heard at the apex of the heart and may radiate to the axilla (armpit).

Tricuspid stenosis, on the other hand, causes an early diastolic murmur that is best heard at the lower left sternal edge during inspiration.

Lastly, mitral stenosis causes a rumbling mid-diastolic murmur that is best heard at the apex of the heart. To listen for this murmur, the patient should be in the left lateral position, and the stethoscope bell should be used during expiration.

Hyperkalaemia is a condition where the level of potassium in the blood is higher than normal, specifically greater than 5.5 mmol/l. It can be categorized as mild, moderate, or severe depending on the specific potassium levels. Mild hyperkalaemia is when the potassium level is between 5.5-5.9 mmol/l, moderate hyperkalaemia is between 6.0-6.4 mmol/l, and severe hyperkalaemia is when the potassium level exceeds 6.5 mmol/l. The most common cause of hyperkalaemia in renal failure, which can be either acute or chronic. Other causes include acidosis, adrenal insufficiency, cell lysis, and excessive potassium intake.

If the patient’s life is not immediately at risk due to an arrhythmia, the initial treatment for hyperkalaemia should involve the use of a beta-2 agonist, such as salbutamol (2.5-10 mg). Salbutamol activates cAMP, which stimulates the Na+/K+ ATPase pump. This action helps shift potassium into the intracellular compartment. The effects of salbutamol are rapid, typically occurring within 30 minutes. With the recommended dose, a decrease in the serum potassium level of approximately 1 mmol can be expected.

In managing patients with carbon monoxide poisoning, the primary intervention is providing 100% oxygen. This is because carbon monoxide has a higher affinity for hemoglobin than oxygen, leading to decreased oxygen delivery to tissues. By administering 100% oxygen, the patient is able to displace carbon monoxide from hemoglobin and increase oxygen levels in the blood, which is crucial for the patient’s recovery.

Further Reading:

Carbon monoxide (CO) is a dangerous gas that is produced by the combustion of hydrocarbon fuels and can be found in certain chemicals. It is colorless and odorless, making it difficult to detect. In England and Wales, there are approximately 60 deaths each year due to accidental CO poisoning.

When inhaled, carbon monoxide binds to haemoglobin in the blood, forming carboxyhaemoglobin (COHb). It has a higher affinity for haemoglobin than oxygen, causing a left-shift in the oxygen dissociation curve and resulting in tissue hypoxia. This means that even though there may be a normal level of oxygen in the blood, it is less readily released to the tissues.

The clinical features of carbon monoxide toxicity can vary depending on the severity of the poisoning. Mild or chronic poisoning may present with symptoms such as headache, nausea, vomiting, vertigo, confusion, and weakness. More severe poisoning can lead to intoxication, personality changes, breathlessness, pink skin and mucosae, hyperpyrexia, arrhythmias, seizures, blurred vision or blindness, deafness, extrapyramidal features, coma, or even death.

To help diagnose domestic carbon monoxide poisoning, there are four key questions that can be asked using the COMA acronym. These questions include asking about co-habitees and co-occupants in the house, whether symptoms improve outside of the house, the maintenance of boilers and cooking appliances, and the presence of a functioning CO alarm.

Typical carboxyhaemoglobin levels can vary depending on whether the individual is a smoker or non-smoker. Non-smokers typically have levels below 3%, while smokers may have levels below 10%. Symptomatic individuals usually have levels between 10-30%, and severe toxicity is indicated by levels above 30%.

When managing carbon monoxide poisoning, the first step is to administer 100% oxygen. Hyperbaric oxygen therapy may be considered for individuals with a COHb concentration of over 20% and additional risk factors such as loss of consciousness, neurological signs, myocardial ischemia or arrhythmia, or pregnancy. Other management strategies may include fluid resuscitation, sodium bicarbonate for metabolic acidosis, and mannitol for cerebral edema.

Bronchiolitis is a short-term infection of the lower respiratory tract that primarily affects infants aged 2 to 6 months. It is commonly caused by a viral infection, with respiratory syncytial virus (RSV) being the most prevalent culprit. RSV infections are most prevalent during the winter months, typically occurring between November and March. In the UK, bronchiolitis is the leading cause of hospitalization among infants.

The typical symptoms of bronchiolitis include fever, difficulty breathing, coughing, poor feeding, irritability, apnoeas (more common in very young infants), and wheezing or fine inspiratory crackles. To confirm the diagnosis, a nasopharyngeal aspirate can be taken for RSV rapid testing. This test is useful in preventing unnecessary further testing and facilitating the isolation of the affected infant.

Most infants with acute bronchiolitis experience a mild, self-limiting illness that does not require hospitalization. Treatment primarily focuses on supportive measures, such as ensuring adequate fluid and nutritional intake and controlling the infant’s temperature. The illness typically lasts for 7 to 10 days.

However, hospital referral and admission are recommended in certain cases, including poor feeding (less than 50% of usual intake over the past 24 hours), lethargy, a history of apnoea, a respiratory rate exceeding 70 breaths per minute, nasal flaring or grunting, severe chest wall recession, cyanosis, oxygen saturations below 90% for children aged 6 weeks and over, and oxygen saturations below 92% for babies under 6 weeks or those with underlying health conditions.

If hospitalization is necessary, treatment involves supportive measures, supplemental oxygen, and nasogastric feeding as needed. There is limited or no evidence supporting the use of antibiotics, antivirals, bronchodilators, corticosteroids, hypertonic saline, or adrenaline nebulizers in the management of bronchiolitis.

A summary of the vessels involved in different types of myocardial infarction, along with the corresponding ECG leads and the location of the infarction.

For instance, an anteroseptal infarction involving the left anterior descending artery is indicated by ECG leads V1-V3. Similarly, an anterior infarction involving the left anterior descending artery is indicated by leads V3-V4.

In cases of anterolateral infarctions, both the left anterior descending artery and the left circumflex artery are involved, and this is reflected in ECG leads V5-V6. An extensive anterior infarction involving the left anterior descending artery is indicated by leads V1-V6.

Lateral infarcts involving the left circumflex artery are indicated by leads I, II, aVL, and V6. Inferior infarctions, on the other hand, involve either the right coronary artery (in 80% of cases) or the left circumflex artery (in 20% of cases), and this is shown by leads II, III, and aVF.

In the case of a right ventricular infarction, the right coronary artery is involved, and this is indicated by leads V1 and V4R. Lastly, a posterior infarction involving the right coronary artery is shown by leads V7-V9.

Appendicitis is a condition characterized by the acute inflammation of the appendix. It is a common cause of the acute abdomen, particularly affecting children and young adults in their 20s and 30s. The typical presentation of appendicitis involves experiencing poorly localized periumbilical pain, which is pain originating from the visceral peritoneum. Within a day or two, this pain tends to localize to a specific point known as McBurney’s point, which is associated with pain from the parietal peritoneum. Alongside the pain, individuals with appendicitis often experience symptoms such as fever, loss of appetite, and nausea.

McBurney’s point is defined as the point that lies one-third of the distance from the anterior superior iliac spine to the umbilicus. This point roughly corresponds to the most common position where the base of the appendix attaches to the caecum.

Nephrogenic diabetes insipidus may develop in a certain percentage of individuals who take lithium.

Further Reading:

Diabetes insipidus (DI) is a condition characterized by either a decrease in the secretion of antidiuretic hormone (cranial DI) or insensitivity to antidiuretic hormone (nephrogenic DI). Antidiuretic hormone, also known as arginine vasopressin, is produced in the hypothalamus and released from the posterior pituitary. The typical biochemical disturbances seen in DI include elevated plasma osmolality, low urine osmolality, polyuria, and hypernatraemia.

Cranial DI can be caused by various factors such as head injury, CNS infections, pituitary tumors, and pituitary surgery. Nephrogenic DI, on the other hand, can be genetic or result from electrolyte disturbances or the use of certain drugs. Symptoms of DI include polyuria, polydipsia, nocturia, signs of dehydration, and in children, irritability, failure to thrive, and fatigue.

To diagnose DI, a 24-hour urine collection is done to confirm polyuria, and U&Es will typically show hypernatraemia. High plasma osmolality with low urine osmolality is also observed. Imaging studies such as MRI of the pituitary, hypothalamus, and surrounding tissues may be done, as well as a fluid deprivation test to evaluate the response to desmopressin.

Management of cranial DI involves supplementation with desmopressin, a synthetic form of arginine vasopressin. However, hyponatraemia is a common side effect that needs to be monitored. In nephrogenic DI, desmopressin supplementation is usually not effective, and management focuses on ensuring adequate fluid intake to offset water loss and monitoring electrolyte levels. Causative drugs need to be stopped, and there is a risk of developing complications such as hydroureteronephrosis and an overdistended bladder.

Activated charcoal is a commonly used substance for decontamination in cases of poisoning. Its main function is to adsorb the molecules of the ingested toxin onto its surface.

Activated charcoal is a chemically inert form of carbon. It is a fine black powder that has no odor or taste. It is produced by subjecting carbonaceous matter to high heat, a process known as pyrolysis, and then treating it with a zinc chloride solution to increase its concentration. This process creates a network of pores within the charcoal, giving it a large absorptive area of approximately 3,000 m2/g. This allows it to effectively inhibit the absorption of toxins by up to 50%.

The usual dose of activated charcoal is 50 grams for adults and 1 gram per kilogram of body weight for children. It can be administered orally or through a nasogastric tube. It is important to administer it within one hour of ingestion, and it may be repeated after one hour if necessary.

However, there are certain situations where activated charcoal should not be used. These include cases where the patient is unconscious or in a coma, as there is a risk of aspiration. It should also be avoided if seizures are imminent, as there is a risk of aspiration. Additionally, if there is reduced gastrointestinal motility, activated charcoal should not be used to prevent the risk of obstruction.

Activated charcoal is effective in treating overdose with certain drugs and toxins, such as aspirin, paracetamol, barbiturates, tricyclic antidepressants, digoxin, amphetamines, morphine, cocaine, and phenothiazines. However, it is ineffective in cases of overdose with iron, lithium, boric acid, cyanide, ethanol, ethylene glycol, methanol, malathion, DDT, carbamate, hydrocarbon, strong acids, or alkalis.

There are potential adverse effects associated with the use of activated charcoal. These include nausea and vomiting, diarrhea, constipation, bezoar formation (a mass of undigested material that can cause blockages), bowel obstruction, pulmonary aspiration (inhalation of charcoal into the lungs), and impaired absorption of oral medications or antidotes.

Klumpke’s palsy, also known as Dejerine-Klumpke palsy, is a condition where the arm becomes paralyzed due to an injury to the lower roots of the brachial plexus. The most commonly affected root is C8, but T1 can also be involved. The main cause of Klumpke’s palsy is when the arm is pulled forcefully in an outward position during a difficult childbirth. It can also occur in adults with apical lung carcinoma (Pancoast’s syndrome).

Clinically, Klumpke’s palsy is characterized by a deformity known as ‘claw hand’, which is caused by the paralysis of the intrinsic hand muscles. There is also a loss of sensation along the ulnar side of the forearm and hand. In some cases where T1 is affected, a condition called Horner’s syndrome may also be present.

Klumpke’s palsy can be distinguished from Erb’s palsy, which affects the upper roots of the brachial plexus (C5 and sometimes C6). In Erb’s palsy, the arm hangs by the side with the elbow extended and the forearm turned inward (known as the ‘waiter’s tip sign’). Additionally, there is a loss of shoulder abduction, external rotation, and elbow flexion.