Osteoclasts are a type of bone cell that breaks down bone tissue. This is a critical function in the maintenance, repair and remodelling of bones. The osteoclast disassembles and digests the composite of hydrated protein and minerals at a molecular level by secreting acid and collagenase. This process is known as bone resorption and also helps to regulate the plasma calcium concentration.Osteoclastic activity is controlled by a number of hormones:1,25-dihydroxycholecalciferol increases osteoclastic activityParathyroid hormone increases osteoclastic activityCalcitonin inhibits osteoclastic activityBisphosphonates are a class of drug that slow down and prevent bone damage. They are osteoclast inhibitors.

In the United Kingdom, propofol is the most widely used intravenous anaesthetic. In adults and children, it can be used to induce or maintain anaesthesia, although it is not commonly used in newborns. It can also be used to sedate individuals in intensive care and for sedation during operations.

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.

Common side effects of amiodarone include: Bradycardia, Nausea and vomiting, Thyroid disorders – hypothyroidism and hyperthyroidism, Persistent slate grey skin discoloration, Photosensitivity, Pulmonary toxicity (including pneumonitis and fibrosis), Hepatotoxicity, Corneal microdeposits (sometimes with night glare), Peripheral neuropathy and Sleep disorders.

The maximum daily dose of paracetamol in an adult is 4 grams. Doses greater than this can lead to hepatotoxicity and, less frequently, acute kidney injury. Early symptoms of paracetamol toxicity include nausea, vomiting, and abdominal pain, and usually settle within 24 hours. Symptoms of liver damage include right subcostal pain and tenderness, and this peaks 3 to 4 days after paracetamol ingestion. Other signs of hepatic toxicity include encephalopathy, bleeding, hypoglycaemia, and cerebral oedema.

CSF fills the ventricular system, a series of interconnected spaces within the brain, and the subarachnoid space directly surrounding the brain. The intraventricular CSF reflects the composition of the brain’s extracellular space via free exchange across the ependyma, and the brain “floats” in the subarachnoid CSF to minimize the effect of external mechanical forces. The volume of CSF within the cerebral ventricles is approximately 30 mL, and that in the subarachnoid space is about 125 mL. Because about 0.35 mL of CSF is produced each minute, CSF is turned over more than three times daily. Approximately 500 mL of CSF is produced per day, at a rate of about 25 mL per hour.CSF is a filtrate of capillary blood formed largely by the choroid plexuses, which comprise pia mater, invaginating capillaries, and ependymal cells specialized for transport. The choroid plexuses are located in the lateral, third, and fourth ventricles. The lateral ventricles are situated within the two cerebral hemispheres. They each connect with the third ventricle through one of the interventricular foramina (of Monro). The third ventricle lies in the midline between the diencephalon on the two sides. The cerebral aqueduct (of Sylvius) traverses the midbrain and connects the third ventricle with the fourth ventricle. The fourth ventricle is a space defined by the pons and medulla below and the cerebellum above. The central canal of the spinal cord continues caudally from the fourth ventricle, although in adult humans the canal is not fully patent and continues to close with age.

Raised platelet levels have emerged as a cancer risk marker, according to a large population-based study published in 2017(link is external). According to the study, 12 percent of men and 6% of women with thrombocytosis were diagnosed with cancer within a year. These figures increased to 18% in men and 10% in women if a second platelet count was taken within 6 months of the first and showed an increased or stable elevated platelet count.The researchers discovered that thrombocytosis linked to cancer is most common in colorectal and lung cancers, and it is linked to a worse prognosis. Furthermore, one-third of the cancer patients in the study had no other symptoms that would have prompted an immediate cancer referral.The exact mechanism by which these cancers cause thrombocytosis is unknown, but one theory proposes the existence of pathogenic feedback loops between malignant cells and platelets, with a reciprocal interaction between tumour growth and metastasis, as well as thrombocytosis and platelet activation. Another hypothesis is that thrombocytosis occurs independently of cancer but aids in its spread and progression.The findings show that routinely testing for thrombocytosis could cut the time it takes to diagnose colorectal and lung cancer by at least two months. In the UK, this could result in around 5500 earlier cancer diagnoses per year.Because the positive predictive value of thrombocytosis in middle age for cancer (10%) is higher than the positive predictive value for a woman in her 50s presenting with a new breast lump (8.5%), this is clearly an important research paper that should be used to adjust future clinical practise. The current NICE guidelines predate these new research findings, so we’ll have to wait and see how they affect cancer referral guidelines in the UK.Because there are so many possible cancers associated with thrombocytosis, the treating clinician should take a thorough history and perform a thorough clinical examination if a patient is diagnosed with it. Further investigation and the most appropriate referral route should be aided by this information.It’s worth noting that the patients in the study had their blood tests done for a medical reason rather than as a random screening test.If there are no other symptoms to guide investigation and referral (one-third of the patients in the study had no other symptoms), keep in mind that the two most common cancers encountered were colorectal and lung cancer, so a chest X-ray and a faecal immunochemical test (FIT) for faecal blood may be reasonable initial investigations.

All patients with adverse features suggesting life-threatening haemodynamic instability (shock, syncope, heart failure, myocardial ischaemia) caused by new onset atrial fibrillation should undergo emergency electrical cardioversion with synchronised DC shock without delaying to achieve anticoagulation.

Aspirin contraindications include: hypersensitivity to NSAIDs; asthma, rhinitis, and nasal polyps; and usage in children or teens.There is little evidence of allergic cross-reactivity for salicylates. However, due to similarities in chemical structure and/or pharmacologic activities, the possibility of cross-sensitivity cannot be completely ruled out.

Peroneus brevis is innervated by the superficial peroneal nerve.Peroneus longus is innervated by the superficial peroneal nerve.Peroneus tertius is innervated by the deep peroneal nerve.