Lithium is the drug of choice for bipolar disorders but is commonly associated with side effects and toxicity.

Fine hand tremor is very commonly seen and reported in as many as 50% of patients during the first week of therapy with Lithium. The tremor tends to reduce with time and is only present in around 5% of patients taking the medication two years or longer. Lithium tremors are more common with older age, presumably due to the additive effects of age-related essential tremors.

Option The normal therapeutic range is 2.0-2.5 mmol/l: Lithium should be carefully monitored as it has a very low therapeutic index. The normal therapeutic range is 0.4-0.8 mmol/l. Levels should be checked one week after starting therapy and one week after every change in dosage. (Option Levels should be checked one month after starting therapy)

Option It can induce hyperthyroidism: Lithium has a known effect on thyroid function. Lithium decreases the production of T4 and T3 and commonly causes hypothyroidism. More rarely, lithium causes hyperthyroidism due to thyroiditis.

Option It can induce diabetes mellitus: Lithium can induce nephrogenic diabetes insipidus but not diabetes mellitus.

Lidocaine is a tertiary amine that is primarily used as a local anaesthetic but can also be used intravenously in the treatment of ventricular dysrhythmias.
Lidocaine works as a local anaesthetic by diffusing in its uncharged base form through neural sheaths and the axonal membrane to the internal surface of the cell membrane sodium channels. Here it alters signal conduction by blocking the fast voltage-gated sodium channels. With sufficient blockage, the membrane of the postsynaptic neuron will not depolarise and will be unable to transmit an action potential, thereby preventing the transmission of pain signals.
Each 1 ml of plain 1% lidocaine solution contains 10 mg of lidocaine hydrochloride. The maximum safe dose of plain lidocaine is 3 mg/kg. When administered with adrenaline 1:200,000, the maximum safe dose is 7 mg/kg. Because of the risk of vasoconstriction and tissue necrosis, lidocaine should not be used in combination with adrenaline in extremities such as fingers, toes, and the nose.
The half-life of lidocaine is 1.5-2 hours. Its onset of action is rapid within a few minutes, and it has a duration of action of 30-60 minutes when used alone. Its duration of action is prolonged by co-administration with adrenaline (about 90 minutes).
Lidocaine tends to cause vasodilatation when used locally. This is believed to be due mainly to the inhibition of action potentials via sodium channel blocking in vasoconstrictor sympathetic nerves.

Fracture dislocations of the elbow appear extremely complex, and identification of the basic injury patterns can facilitate management. The simplest pattern of elbow fracture dislocation is posterior dislocation of the elbow with fracture of the radial head. Addition of a coronoid fracture, no matter how small, to elbow dislocation and radial head fracture is called the terrible triad of the elbow.

A funnel plot is a scatter plot of the effect estimates from individual studies against some measure of each study’s size or precision. The standard error of the effect estimate is often chosen as the measure of study size and plotted on the vertical axis with a reversed scale that places the larger, most powerful studies towards the top. The effect estimates from smaller studies should scatter more widely at the bottom, with the spread narrowing among larger studies. In the absence of bias and between study heterogeneity, the scatter will be due to sampling variation alone and the plot will resemble a symmetrical inverted funnel. A triangle centred on a fixed effect summary estimate and extending 1.96 standard errors either side will include about 95% of studies if no bias is present and the fixed effect assumption (that the true treatment effect is the same in each study) is valid.

Chloramphenicol is a broad-spectrum antibiotic that inhibits bacterial protein synthesis by blocking the 50S subunit of the bacterial ribosome’s peptidyl transferase activity. When administered systemically, it has limited usage due to the potential of significant side effects such as aplastic anaemia, peripheral neuropathy, and optic neuritis. It’s only used to treat typhoid fever and Haemophilus influenzae meningitis, but it’s usually better to use a broad-spectrum cephalosporin.

The auriculotemporal nerve is irritated by mumps, which results in significant discomfort due to inflammation and swelling of the parotid gland, as well as the stretching of its capsule. Compression caused by swallowing or chewing exacerbates pain.

Funnel plots are used to demonstrate the existence of publication bias in meta-analysis. Funnel plots are scatter plots of treatment effects estimated from individual studies on the x axis and some measure of study size on the y axis. Each point on the graph represents one of the studies. A symmetrical inverted funnel shape indicates an absence of publication bias. If there is publication bias, there will be asymmetry of the open wide end due to the absence of small negative results.

All vaccines are contraindicated in individuals with:
A confirmed anaphylactic reaction to a previous dose of the vaccine or a vaccine containing the same antigens.
A confirmed anaphylactic reaction to a component in the vaccine e.g. neomycin

Live attenuated vaccines are contraindicated in pregnancy except in cases where risk of infection is more than the risks of vaccination.

During times of acute febrile illness, vaccination should be avoided.

12 weeks should elapse after a dose of human immunoglobulin before a live vaccine is administered.

The normal times recommended for immunization of full-term babies should also be applied to premature infants and correction for gestational age should NOT be implemented.

Acute severe hypernatraemia is a medical emergency and requires inpatient management in a high dependency setting. Seizures and intracranial vascular haemorrhage as a result of brain cell crenation can occur. The cause is most commonly excessive water loss and the key aspect of treatment is aggressive fluid replacement (typically with normal saline as this is relatively hypotonic). If urine osmolality is low, diabetes insipidus (DI )should be considered and a trial of synthetic ADH given. In patients with known DI, it is essential to ensure synthetic ADH is given parenterally and that close fluid balance is observed.

Osmolality and osmolarity are measurements of the solute concentration of a solution. Although the two terms are often used interchangeably, there are differences in the definitions, how they are calculated and the units of measurement used.

Osmolarity, expressed as mmol/L, is an estimation of the osmolar concentration of plasma. It is proportional to the number of particles per litre of solution.
Measured Na+, K+, urea and glucose concentrations are used to calculate the value indirectly.
It is unreliable in pseudohyponatremia and hyperproteinaemia.

The equations used to calculate osmolarity are:
Osmolarity = 2 (Na+) + 2 (K+) + Glucose + Urea (all in mmol/L)
OR
Osmolarity = 2 (Na+) + Glucose + Urea (all in mmol/L)

Doubling of sodium accounts for the negative ions associated with sodium, and the exclusion of potassium approximately allows for the incomplete dissociation of sodium chloride.

C. diphtheriae, which is the causative agent of diphtheria, is carried in the upper respiratory tract and spread by droplet infection or hand-to-mouth contact. The incubation period averages 2 to 5 days.

Infectious mononucleosis is caused by Epstein-Barr virus (EBV). The incubation period for EBV varies from 2 weeks to 2 months.

The incubation for Hepatitis A virus is approximately 1 month.

The incubation period for Hepatitis C ranges from 2 weeks to 6 months.

The period from infection to development of anti-HIV antibodies is usually less than 1 month but may be up to 3 months.

Malaria is an infectious disease transmitted by female of theAnophelesgenus of mosquito. It is a parasitic infection caused by the genusPlasmodium. Five species are recognized as causing disease in humans;Plasmodium falciparum,Plasmodium ovale,Plasmodium vivax,Plasmodium malariaeandPlasmodium knowlesi.
The classic symptom of malaria is the malarial paroxysm, a cyclical occurrence of a cold phase, where the patient experiences intense chills, a hot stage, where the patient feels extremely hot and finally a sweating stage, where the fever declines and the patient sweats profusely. On examination the patient may show signs of anaemia, jaundice and have hepatosplenomegaly without evidence of lymphadenopathy.

Plasmodium falciparum is the most serious form and is responsible for most deaths. Severe or complicated malaria is suggested by the presence of impaired consciousness, seizures, hypoglycaemia, anaemia, renal impairment, respiratory distress and spontaneous bleeding.
Plasmodium falciparum is the most likely type in this case in view of the presentation.
Haemoglobinuria and renal failure following treatment is suggestive of blackwater fever, which is caused byPlasmodium falciparum. An autoimmune reaction between the parasite and quinine causes haemolysis, haemoglobinuria, jaundice and renal failure. This can be fatal.
The benign malarias: P.vivax, P. malariae and P.ovale are usually treated with chloroquine. A course of primaquine is also required in P.vivax and P.ovale infection. Artesunate is the drug treatment of choice for Plasmodium falciparum malaria. Quinine can still be used where artesunate is not available. Often combination therapy with drugs such as doxycycline or fansidar is also required.

Damage to the hypoglossal nerve results in weakness of the tongue, with deviation of the tongue towards the weak side on protrusion.

Graves disease is the most common cause of hyperthyroidism. It is an autoimmune disease in which autoantibodies against TSH receptors are produced. These antibodies bind to and stimulate these TSH receptors leading to an excess production of thyroid hormones. Therefore, the signs and symptoms of Graves disease are the same as those of hyperthyroidism, reflecting the actions of increased circulating levels of thyroid hormones: increased heat production, weight loss, increased 02 consumption and cardiac output and exophthalmos (bulging eyes, not drooping eyelids). TSH levels will be decreased (not increased) as a result of the negative feedback effect of increased T3 levels on the anterior pituitary.

Extensor hallucis longus is innervated by the deep fibular nerve (root value L5 and S1).

Blood loss from the gastrointestinal (GI) tract is the most common cause of iron deficiency anaemia in adult men and postmenopausal women.

DIC is characterised by a widespread inappropriate intravascular deposition of fibrin with consumption of coagulation factors and platelets. This may occur as a consequence of many disorders that release procoagulant material into the circulation or cause widespread endothelial damage or platelet aggregation. Increased activity of thrombin in the circulation overwhelms its normal rate of removal by natural anticoagulants. In addition to causing increased deposition of fibrin in the microcirculation and widespread platelet aggregation to the vessels, intravascular thrombin formation interferes with fibrin polymerisation. Intense fibrinolysis is stimulated by thrombi on vascular walls and the release of fibrin degradation products again interferes with fibrin polymerisation. The combined action of thrombin and plasmin causes depletion of fibrinogen and all coagulation factors, compounded by thrombocytopaenia caused by platelet consumption.

Tuberculosis is an infection caused by the microorganism Mycobacterium tuberculosis. TB can affect any organ system in the body, but it most commonly affects the lungs, followed by the lymph nodes.

Option Tuberculosis is spread by the faecal-oral route: It is spread by inhalation of droplet nuclei.

There are different methods to diagnose a tuberculosis infection.
1) Direct Microscopy: The organisms are visualised using Ziehl-Neelsen or Auramine staining. This is the quickest method to establish a diagnosis and start treatment.
2) Culture: M. tuberculosis can be grown on Lowenstein-Jensen or Ogawa mediums, but it can take up to 8 weeks; therefore, ZN staining is also performed to start treatment immediately.

Option There are several types of vaccine currently available: The BCG vaccine is the only vaccine approved to prevent TB and is administered at birth.

Option Miliary tuberculosis refers to tuberculosis that affects the spine: Miliary tuberculosis refers to a tuberculosis infection disseminated throughout the body’s organ systems via the blood or lymphatics. Pott’s disease is extrapulmonary TB that affects the spine. It usually affects the lower thoracic and upper lumbar regions.

Option A Ghon focus typically appears at the apex of a lung: The Ghon focus is a primary sign of TB that forms in the lung of previously unaffected patients. It typically occurs in the mid or lower zones of the lung.

Gastric emptying is decreased by:
Enterogastric inhibitory reflexes stimulated by – Distension of the duodenum, The presence of fats in the duodenum (by stimulating release of cholecystokinin), A fall in the pH of chyme in the duodenum, An increase in the osmolality of chyme in the duodenum, Irritation of the mucosal lining of the duodenum, Hormones: Cholecystokinin, Secretin

Acute bronchiolitis is caused most commonly by respiratory syncytial virus, occurring mostly in children aged 6 months to 2 years. Children with bronchiolitis are febrile and tachypnoeic with a dry cough and difficulty feeding. Examination may reveal chest hyperinflation, respiratory distress, wheezing and fine end-inspiratory crepitations. Chest x-ray may show hyperinflation and increased peribronchial markings (although CXR should only performed if there is diagnostic uncertainty or an atypical course). Treatment is usually supportive, aerosolized ribavirin is reserved for severely ill or immunocompromised patients.

Latissimus dorsi originates from the lower part of the back, where it covers a wide area. It lies underneath the inferior fibres of trapezius superiorly, and trapezius is the most superficial back muscle.
Superficial muscles of the back showing latissimus dorsi (from Gray’s Anatomy)
Latissimus dorsi has a broad origin, arising from the spinous processes of T6-T12, the thoracolumbar fascia, the iliac crest and the inferior 3 or 4 ribs. The fibres converge into a tendon that inserts into the intertubercular groove of the humerus.
Latissimus dorsi is innervated by the thoracodorsal nerve.
Latissimus dorsi acts to extend, adduct and medially rotate the humerus. It, therefore, raises the body towards the arm during climbing.

Extrapyramidal side effects are most common with piperazine phenothiazines (fluphenazine, prochlorperazine, and trifluoperazine) and butyrophenones (fluphenazine, prochlorperazine, and trifluoperazine) (benperidol and haloperidol). The most common causative antipsychotic drug is haloperidol.

Tardive dyskinesia (rhythmic, involuntary movements of the tongue, face, and jaw) is most commonly associated with long-term or high-dose treatment. It is the most serious form of extrapyramidal symptoms because withdrawal of the causative drug may make it irreversible, and treatment is usually ineffective.

Dystonia (abnormal facial and body movements) is more common in children and young adults, and it usually shows up after only a few doses. Procyclidine 5 mg IV or benzatropine 2 mg IV as a bolus can be used to treat acute dystonia.

An unpleasant feeling of restlessness characterises akathisia. The inability to initiate movement is known as akinesia.

Renal impairment causes increased cerebral sensitivity, so lower doses should be used.

In elderly patients with dementia-related psychosis who are treated with haloperidol, there is an increased risk of death. This appears to be due to a higher risk of heart attacks and infections like pneumonia.

The following are some of the antipsychotic drugs’ contraindications:
Reduced level of consciousness/coma
Depression of the central nervous system
Phaeochromocytoma

A supracondylar fracture is a fracture that occurs through the thin section of the distal humerus above the growth plate.

A supracondylar fracture is most usually associated with median nerve injury. A medial nerve damage causes paralysis of the thenar muscles, as well as loss of thumb opposition.

Adverse effects include:
Common: Nausea
Uncommon: Vomiting
Rare: Abdominal pain, hypertension, hypotension, tachycardia

Digoxin is excreted through the kidneys, and impaired renal function can lead to elevated digoxin levels and toxicity.
The patient’s digoxin dose should be reduced in this case, and their digoxin level and electrolytes should be closely monitored.

Cholera is caused by Vibrio cholerae, a motile, Gram-negative, curved bacillus. It is transmitted through water and food (especially seafood) and is primarily a disease seen in developing countries where there is poor sanitation and lack of safe water supplies.

The cholera toxin leads to stimulation of adenyl cyclase, ADP-ribosylation of the G regulatory protein, inactivation of GTPase leading to active outpouring of NaCl.

The cholera toxin consists of an A (the toxin) and B subunit. The B subunit attaches to the gut mucosa and presents the A subunit to the cell. The toxin stimulates adenyl cyclase by irreversible ADP-ribosylation of the GTP binding domain of adenyl cyclase leading to the opening of chloride channels resulting in an outpouring of NaCl and water into the lumen of the gut and causing secretory diarrhoea.

Incubation period is between 2 and 5 days, but can be as short as just a few hours.

Klumpke palsy, named after Augusta Dejerine-Klumpke, is a neuropathy involving the lower brachial plexus. In contrast, the more common Erb–Duchenne palsy involves the more cephalic portion of the brachial plexus C5 to C6. The brachial plexus is a bundle of individual nerves that exit between the anterior and middle scalene muscles in the anterior lateral and basal portion of the neck. Although the most common anatomical presentation of the brachial plexus is between the anterior and middle scalene, there are variations, with the most common being penetration of the anterior scalene. The main mechanism of injury to the lower brachial plexus is hyper-abduction traction, and depending on the intensity, it will lead to signs and symptoms consistent with a neurological insult.

The most common aetiology resulting in Klumpke palsy is a hyper-abduction trauma to the arm that has enough intensity to traction the lower brachial plexus. Trauma during birth can cause brachial plexus injuries, but again hyper-abduction and traction forces to the upper extremity are usually present.

The history presented by the patient usually depicts a long axis hyper-abduction traction injury with high amplitude and velocity. The typical patient presentation is a decrease of sensation along the medial aspect of the distal upper extremity along the C8 and T1 dermatome. The patient might also present myotome findings that can range from decreasing muscular strength to muscular atrophy and positional deformity. For example, if the neurological damage has led to muscular atrophy and tightening, the patient may present with a claw hand. This deformity presents a finger and wrist flexion. The patient may also describe the severe pain that starts at the neck and travels down the medial portion of the arm. One other sign of a lower brachial plexus injury is Horner syndrome; because of its approximation to the T1 nerve root, it may damage the cephalic sympathetic chain. If this happens, the patient will develop ipsilateral ptosis, anhidrosis, and miosis.

Relative risk (RR) is a ratio of the probability of an event occurring in the exposed group versus the probability of the event occurring in the non-exposed group.

RR can be computed as the absolute risk of events in the treatment group (ART), divided by the absolute risk of events in the control group (ARC).

RR = ART/ARC
RR = (10/500) / (25/500)
RR = 0.4

Recall that:

If RR < 1, then the intervention reduces the risk of the outcome.
If RR = 1, then the treatment has no effect on the outcome.
If RR > 1, then the intervention increases the risk of the outcome.

The hormone-active metabolite of vitamin D is 1,25-dihydroxycholecalciferol (commonly known as calcitriol). Its activities raise calcium and phosphate levels in the bloodstream.

The following are the primary effects of 1,25-dihydroxycholecalciferol:

Calcium and phosphate absorption in the small intestine is increased.
Calcium reabsorption in the kidneys is increased.
Increases phosphate reabsorption in the kidneys.
Increases the action of osteoclastic bacteria (increasing calcium and phosphate resorption from bone)
Inhibits the action of 1-alpha-hydroxylase in the kidneys (negative feedback)
Thyroid hormone (parathyroid hormone) Calcium reabsorption in the tubules of the kidneys is increased, but renal phosphate reabsorption is decreased.

Myocardial cells are unable to regenerate, they are unable to divide in response to tissue injury. The remain permanently in G0 and cannot progress to G1. If a segment of muscle dies, for example in myocardial infarction, this tissue will be replaced by scar tissue if the patient recovers. This scar tissue is non-contractile and therefore the remaining myocardium must work harder to maintain cardiac output. As a consequence the remaining undamaged myocardium undergoes compensatory hypertrophy without cell division.