Scleritis, or inflammation of the sclera, is usually painful whereas episcleritis is not painful.

Keratoconjunctivitis sicca is usually bilateral and associated more with dryness, burning and itching.

One of the most important complications in patients with PKD is being affected by berry aneurysms that may burst, causing a subarachnoid haemorrhage, which seems to be the case in this patient.

The rationale behind the use of sodium bicarbonate is that it increases the alkalinity of the urine promoting lithium excretion. The preferred treatment in severe cases would be haemodialysis.

Lithium is a mood-stabilizing drug used most commonly prophylactically in bipolar disorder but also as an adjunct in refractory depression. It has a very narrow therapeutic range (0.4-1.0 mmol/L) and a long plasma half-life being excreted primarily by the kidneys. Lithium toxicity generally occurs following concentrations > 1.5 mmol/L.

Toxicity may be precipitated by dehydration, renal failure, diuretics (especially Bendroflumethiazide), ACE inhibitors, NSAIDs and metronidazole.

Features of toxicity
Coarse tremor (a fine tremor is seen in therapeutic levels)
Hyperreflexia
Acute confusion
Seizure
Coma

Management
Mild-moderate toxicity may respond to volume resuscitation with normal saline
Haemodialysis may be needed in severe toxicity
Sodium bicarbonate is sometimes used but there is limited evidence to support this. By increasing the alkalinity of the urine it promotes lithium excretion.

Lateral epicondylitis (tennis elbow) is an overuse injury of the hand and finger extensor tendons that originate in the lateral humeral epicondyle that occurs following repeated or excessive pronation/supination and extension of the wrist (e.g., in racquet sports). Clinical features include pain and tenderness over the lateral epicondyle and along extensor muscles and thickening of the tendons. The examiner holds the patient’s hand with the thumb placed over the lateral epicondyle – The patient makes a fist, supinates the forearm, deviates radially, and extends the fist against the examiner’s resistance which will result in pain over the lateral epicondyle. Conservative treatment includes rest, physiotherapy and orthotic braces. If this fails corticosteroids and lidocaine injections are employed. Surgery is indicated in patients with persistent symptoms despite 6 months of conservative treatment. Excision of abnormal tendon tissue; longitudinal incisions (tenotomies) in scarred and fibrotic areas to promote healing.

Cyanide poisoning:
Aetiology:
Smoke inhalation, suicidal ingestion, and industrial exposure (specific industrial processes involving cyanide include metal cleaning, reclaiming, or hardening; fumigation; electroplating; and photo processing) are the most frequent sources of cyanide poisoning. Treatment with sodium nitroprusside or long-term consumption of cyanide-containing foods is a possible source.
Cyanide exposure most often occurs via inhalation or ingestion, but liquid cyanide can be absorbed through the skin or eyes. Once absorbed, cyanide enters the blood stream and is distributed rapidly to all organs and tissues in the body. 

Pathophysiology:
Inside cells, cyanide attaches itself to ubiquitous metalloenzymes, rendering them inactive. Its principal toxicity results from inactivation of cytochrome oxidase (at cytochrome a3), thus uncoupling mitochondrial oxidative phosphorylation and inhibiting cellular respiration, even in the presence of adequate oxygen stores.

Presentation:
• ‘Classical’ features: brick-red skin, smell of bitter almonds
• Acute: hypoxia, hypotension, headache, confusion
• Chronic: ataxia, peripheral neuropathy, dermatitis

Management:
• Supportive measures: 100% oxygen, ventilatory assistance in the form of intubation if required.
• Definitive: Hydroxocobalamin (iv) is considered the drug of choice and is approved by the FDA for treating known or suspected cyanide poisoning.
• Coadministration of sodium thiosulfate (through a separate line or sequentially) has been suggested to have a synergistic effect on detoxification.
Mechanism of action of hydroxocobalamin:
• Hydroxocobalamin combines with cyanide to form cyanocobalamin (vitamin B-12), which is renally cleared.
• Alternatively, cyanocobalamin may dissociate from cyanide at a slow enough rate to allow for cyanide detoxification by the mitochondrial enzyme rhodanese.

In general, the aim is to keep the homocysteine (Hcy) concentration as close to normal as possible. In patients who are fully-responsive to pyridoxine, standard doses can lead to tHcy levels below 50 μmol/L (and sometimes within the normal range). Some patients who are partially-responsive to pyridoxine may be able to achieve a tHcy level below 50 μmol/L if they are also on a low-Met diet; for others it is not a realistic goal.

Ethanol competes with ethylene glycol for alcohol dehydrogenase and thus, helps manage a patient with ethylene glycol toxicity.

Ethylene glycol is a type of alcohol used as a coolant or antifreeze
Features of toxicity are divided into 3 stages:
Stage 1: (30 min to 12 hours after exposure) Symptoms similar to alcohol intoxication: confusion, slurred speech, dizziness (CNS depression)
Stage 2: (12 – 48 hours after exposure) Metabolic acidosis with a high anion gap and high osmolar gap. Also tachycardia, hypertension
Stage 3: (24 – 72 hours after exposure) Acute renal failure

Management has changed in recent times:
Fomepizole, an inhibitor of alcohol dehydrogenase, is now used first-line in preference to ethanol.
Ethanol has been used for many years works by competing with ethylene glycol for the enzyme alcohol dehydrogenase this limits the formation of toxic metabolites (e.g. glycolaldehyde and glycolic acid) which are responsible for the hemodynamic/metabolic features of poisoning.
Haemodialysis has a role in refractory cases.

Haemoptysis is a symptom which indicates the worsening of mitral stenosis. It occurs due to the rupture of pulmonary veins or the capillary system due to pulmonary venous hypertension. Elevated serum creatinine is seen in worsening aortic stenosis. Worsening of tricuspid regurgitation causes ascites and a pulsatile liver.

This patient meets the diagnostic criteria for neutropenic sepsis, which is a relatively common complication of cancer therapy – usually chemotherapy occurring 7–14 days after. It is defined as a neutrophil count of <0.5 x 10^9/L in a patient undergoing anticancer treatment and who has either a temperature higher than 38°C or has other features consistent with clinically significant sepsis. Management approach is the same as mentioned in this case. However, if the patient still remains unwell, then an antifungal such as amphotericin B is started after risk-stratifying the patient and carrying out investigations (e.g. HRCT and Aspergillus PCR) to determine the likelihood of systemic fungal infection.

The most probable diagnosis in this patient is conversion disorder.

There may be underlying tension regarding her musical career which could be manifesting as apparent limb weakness.

Conversion disorder typically involves loss of motor or sensory function. The patient doesn’t consciously feign the symptoms (factitious disorder) or seek material gain (malingering). Patients may be indifferent to their apparent disorder – la belle indifference – although this has not been backed up by studies.

Other options:
Unexplained symptoms
There are a wide variety of psychiatric terms for patients who have symptoms for which no organic cause can be found:

Somatization disorder
Multiple physical symptoms present for at least 2 years
the patient refuses to accept reassurance or negative test results

Hypochondriacal disorder
The persistent belief in the presence of an underlying serious disease, e.g. cancer.
The patient again refuses to accept reassurance or negative test results

Dissociative disorder
Dissociation is a process of ‘separating off’ certain memories from normal consciousness
Unlike conversion disorder, it involves psychiatric symptoms e.g. amnesia, fugue, stupor
Dissociative identity disorder (DID) is the new term for multiple personality disorder as is the most severe form of dissociative disorder

Munchausen’s syndrome
Also known as factitious disorder
The intentional production of physical or psychological symptoms

Malingering
Fraudulent simulation or exaggeration of symptoms with the intention of financial or another gain.

In myasthenia gravis, repeated muscle contractions lead to reduced muscle strength. The opposite is however classically seen in the related disorder Lambert-Eaton syndrome. Lambert-Eaton myasthenic syndrome is seen in association with small cell lung cancer, and to a lesser extent breast and ovarian cancer. It may also occur independently as an autoimmune disorder. Lambert-Eaton myasthenic syndrome is caused by an antibody directed against pre-synaptic voltage gated calcium channel in the peripheral nervous system.

The most appropriate steps of initial management include iv glucagon and iv isoprenaline.

The most likely diagnosis in the above scenario (decreased conscious level, profound hypertension, and bradycardia) is β-blocker toxicity/overdose.
Bronchospasm rarely occurs in an overdose of β-blockers, except where there is a history of asthma.

Immediate management is to give iv glucagons (50–150μg/kg) followed by infusion to treat hypotension and isoprenaline or atropine to treat bradycardia.
Where patients fail to respond to these measures, temporary pacing may be required.
If the patient is seen within the first 4 hours of the overdose, gastric lavage may be of value.

The patient’s history points to absence seizures. Carbamazepine has been shown to aggravate generalized seizure types, especially absence seizures, because it acts directly on the ventrobasal complex of the thalamus which is critical to the neurophysiology of absence seizures.

Only cystine stones are semi-opaque because they contain sulphur. All the other stones will appear either radio-lucent or radio-opaque.

Hemiballismus or hemiballism in its unilateral form is a very rare movement disorder. It is a type of chorea caused in most cases by a decrease in activity of the subthalamic nucleus of the basal ganglia, resulting in the appearance of flailing, ballistic, undesired movements of the limbs. Symptoms may decrease while the patient is asleep. Antidopaminergic agents (e.g. Haloperidol) are the mainstay of treatment.

The patient’s history and presentation and familial history, meets the diagnostic criteria for Neurofibromatosis type I, presenting with neurofibromas noted in this patient as hyperpigmented macules and freckles, musculoskeletal disorders like the scoliosis in this case, and a familial history. Neurofibromatosis type I is caused by a mutation on Chromosome 17.

Hereditary C1 inhibitor deficiency leads to recurrent angioedema without urticaria or pruritus. Physical triggers include dental work, surgery or intubation. Medical triggers include angiotensin-converting enzyme (ACE) inhibitor, tamoxifen, oestrogen-containing medications (e.g., hormone replacement therapy and oral contraceptives). It is diagnosed on the basis of low levels of C1 esterase inhibitor or elevated levels of dysfunctional C1 esterase inhibitor. C4 levels are low between attacks. IgE levels, eosinophils, skin prick tests and RASTs are helpful in other allergic conditions and asthma but not of use in this case.

Hyperthyroid patients show significantly lower resting arterial CO2 tension, tidal volume and significantly higher mean inspiratory flow and pa(O2) than healthy patients. This may of course lead to misdiagnosis of patients with hyperthyroidism as having hyperventilation syndrome.

Normal pressure hydrocephalus is a form of communicating hydrocephalus characterised by enlarged ventricles with normal opening pressure on lumbar puncture. For diagnostic purposes, a triad of urinary incontinence, gait abnormality and dementia is necessary. It is necessary to diagnose the condition early because it is reversible by placing a ventriculoperitoneal shunt. It is most common in patients aged more than 60 years.