The primary functions of the Broca area are both language production and comprehension. While the exact role in the production is still unclear, many believe that it directly impacts the motor movements to allow for speech. Although originally thought to only aid in speech production, lesions in the area can rarely be related to impairments in the comprehension of language. Different regions of the Broca area specialize in various aspects of comprehension. The anterior portion helps with semantics, or word meaning, while the posterior is associated with phonology, or how words sound. The Broca area is also necessary for language repetition, gesture production, sentence grammar and fluidity, and the interpretation of others’ actions.Broca’s aphasia is a non-fluent aphasia in which the output of spontaneous speech is markedly diminished and there is a loss of normal grammatical structure. Specifically, small linking words, conjunctions, such as and, or, and but, and the use of prepositions are lost. Patients may exhibit interjectional speech where there is a long latency, and the words that are expressed are produced as if under pressure. The ability to repeat phrases is also impaired in patients with Broca’s aphasia. Despite these impairments, the words that are produced are often intelligible and contextually correct. In pure Broca’s aphasia, comprehension is intact.

Neisseria meningitidisis is a Gram-negative diplococcusc that can cause meningococcal meningitis.Carriage of Neisseria meningitidisis very common and it exists in the normal flora in the nasopharynx in 5 – 15% of adults. Actual disease only develops in a very small percentage of individuals. Infection is most common in the winter months and epidemics tend to occur about once every 10 years.Most invasive infections are caused by serotypes A, B or C. In the UK, most cases of meningococcal septicaemia are caused byNeisseria meningitidisgroup B. The vaccination programme forNeisseria meningitidisgroup C has made this type much less common. A vaccine for group B disease has now been initiated in children.The main determinant of the pathogenicity of Neisseria meningitidisis the antiphagocytic polysaccharide capsule. Meningococci cross mucosal epithelium by endocytosis and the capsule allows survival in the bloodstream. Lipo-oligosaccharide activates complement activation and cytokine release, resulting in shock and disseminated intravascular coagulation (DIC).Theclinical featuresof meningococcal meningitis include:Non-blanching rashNeck stiffnessHeadachePhotophobiaAltered mental state (drowsiness, confusion)Focal neurological deficitsSeizuresSeptic shockThe diagnosis is usually made clinically and confirmed by culture of blood, aspirate from the rash and CSF. Rapid antigen detection or nucleic acid amplification testing (NAAT) on blood and CSF are both sensitive and reliable.Due to the potentially life-threatening nature of the disease treatment should not wait for laboratory confirmation and antibiotics should be started immediately. In the hospital setting IV ceftriaxone (2 g adult; 80 mg/kg child) or IV cefotaxime (2 g adult; 80 mg/kg child) are the preferred agents. IM benzylpenicillin can be given as an alternative in the pre-hospital setting and chloramphenicol is a suitable alternative if there is a history of anaphylaxis to cephalosporins. Treatment does not eradicate carriage and the patient should be given ‘prophylaxis’ following recovery.

The administration of oxygen to a patient before intubation is called pre-oxygenation and it helps extend the ‘safe apnoea time’. The Functional residual capacity (FRC) is the volume of gas that remains in the lungs after normal tidal expiration. It is the most important store of oxygen in the body. The aim of pre-oxygenation is to replace the nitrogen in the FRC with oxygen. Apnoea can be tolerated for longer periods before critical hypoxia develops if the FRC is large. Patients with reduced FRC reach critical hypoxia more rapidly.

Ipratropium bromide is an antimuscarinic drug used in the management of acute asthma and COPD. It can provide short-term relief in chronic asthma, but short-acting β2agonists act more quickly and are preferred.The BTS guidelines recommend that nebulised ipratropium bromide (0.5 mg 4-6 hourly) can be added to β2agonist treatment for patients with acute severe or life-threatening asthma or those with a poor initial response to β2 agonist therapy.The aerosol inhalation of ipratropium can be used for short-term relief in mild chronic obstructive pulmonary disease in patients who are not already using a long-acting antimuscarinic drug (e.g. tiotropium).Its maximum effect occurs 30-60 minutes after use; its duration of action is 3-6 hours, and bronchodilation can usually be maintained with treatment three times per day.The commonest side effect of ipratropium bromide is dry mouth. It can also trigger acute closed-angle glaucoma in susceptible patients. Tremor is commonly seen with β2agonists but not with antimuscarinics. Ipratropium bromide should be used with caution in: Men with prostatic hyperplasia and bladder-outflow obstruction (worsened urinary retention has been reported in elderly men), People with chronic kidney disease (CKD) stages 3 and above (because of the risk of drug toxicity), People with angle-closure glaucoma (nebulised mist of antimuscarinic drugs can precipitate or worsen acute angle-closure glaucoma)

The ventilation/perfusion ratio (V/Q ratio) is a ratio used to assess the efficiency and adequacy of the matching ventilation and perfusion. The ideal V/Q ratio is 1.Any mismatch between ventilation and perfusion will be evident in the V/Q ratio. If perfusion is normal but ventilation is reduced, the V/Q ratio will be less than 1, whereas if ventilation is normal, but perfusion is reduced, the V/Q ratio will be greater than 1. If the alveoli were ventilated but not perfused at all, then the V/Q ratio would be infinity. The V/Q ratio is also affected by location. The various areas of the lungs have a different V/Q ratio since ventilation and perfusion increase from the apex to the base of the lungs. The apex of the lungs has a V/Q ratio of approximately 3.3.

Parkinson’s disease (PD) is one of the most common neurologic disorders, affecting approximately 1% of individuals older than 60 years and causing progressive disability that can be slowed but not halted, by treatment. The 2 major neuropathologic findings in Parkinson’s disease are loss of pigmented dopaminergic neurons of the substantia nigra pars compacta and the presence of Lewy bodies and Lewy neurites. See the images below.

Klebsiella pneumoniae is among the most common Gram-negative bacteria encountered by physicians worldwide and accounts for 0.5-5.0% of all cases of pneumonia. This organism can cause extensive pulmonary necrosis and frequent cavitation.It is one of the causes that could be suspected when there is cavitatory pneumonia with or without a bulging fissure sign. Often, there can be extensive lobar opacification with air bronchograms.A helpful feature which may help to distinguish from pneumococcal pneumonia is that Klebsiella pneumoniae develops cavitation in 30-50% of cases (in comparison, cavitation is rare in pneumococcal pneumonia). This occurs early and progresses quickly.

Hyperkalaemia causes a rapid reduction in resting membrane potential leading to increased cardiac depolarisation and muscle excitability. This in turn results in ECG changes which can rapidly progress to ventricular fibrillation or asystole. Very distinctive ECG changes that progressively change as the K+level increases:K+>5.5 mmol/l – peaked T waves (usually earliest sign of hyperkalaemia), repolarisation abnormalitiesK+>6.5 mmol/l – P waves widen and flatten, PR segment lengthens, P waves eventually disappearK+>7.0 mmol/l – Prolonged QRS interval and bizarre QRS morphology, conduction blocks (bundle branch blocks, fascicular blocks), sinus bradycardia or slow AF, development of a sine wave appearance (a pre-terminal rhythm)K+>9.0 mmol/l – Cardiac arrest due to asystole, VF or PEA with a bizarre, wide complex rhythm.

Although Addisonian crisis is a rare illness, it can be fatal if it is misdiagnosed. Hypoglycaemia and shock are the most common symptoms of an Addisonian crisis (tachycardia, peripheral vasoconstriction, hypotension, altered conscious level, and coma).Other clinical characteristics that may be present are:FeverPsychosisLeg and abdominal painDehydration and vomitingConvulsions 

Haemophilia B is a bleeding disorder caused by a deficiency of clotting factor IX. It is the second commonest form of haemophilia, and is rarer than haemophilia A. Haemophilia B tends to be similar to haemophilia A but less severe. The two disorders can only be distinguished by specific coagulation factor assays.The incidence is one-fifth of that of haemophilia A. Laboratory findings demonstrate prolonged APTT, normal PT and low factor IX.Haemophilia B inherited in an X-linked recessive fashion, affecting males born to carrier mothers.There is also a variation called Leyden, in which factor IX levels are below 1% until puberty, when they rise, potentially reaching as high as 40-60% of normal. This is thought to be due to the effects of testosterone at puberty.