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PLAB 1 Question 5

Neisseria meningitidis plated on blood agar

Question.

A 56-year-old male, diabetic, is presenting with recurrent brief headache for 3 weeks, affecting one side of the head and almost always around mouth, increasing with eating and loud laughing and resolves in minutes. On examination his temperature is 37.1C, random capillary glucose is 7.5 mmol/l, and his blood pressure is 110/70 mmHg. No neck stiffness, skin rash, or facial oedema. What is the most appropriate treatment?

        1. Psychotherapy
        2. Prednisolone
        3. Carbamazepine
        4. Sumatriptan
        5. Losartan

    Answer.

    3. 

     
    Explanation.

    Trigeminal neuralgia usually presents with paroxysms of intense, stabbing pain, in the trigeminal nerve distribution, typically affecting the mandibular or maxillary divisions on one side. It can be triggered with Washing the affected area, shaving, eating, and laughing. It’s more common in males above 50 years old. Diagnosis depends on looking for a secondary cause Compressing the trigeminal root by anomalous or aneurysmal intracranial vessels or a tumour, zoster, or skull base malformation. MRI Is necessary to exclude secondary causes. Carbamazepine is the first line treatment. Surgery may be needed in refractory cases.
     

PLAB 1 Question 52021-08-06T14:30:53+01:00

PLAB 1 Question 4

Neisseria meningitidis plated on blood agar

Question.

A 65-year-old gentleman with no previous surgical history, underwent total hip replacement. He complains of abdominal distension, constipation and vomiting but no significant pain 2 days after surgery. Examination reveals absent bowel sounds and xray abdomen shows multiple gas, fluid levels in small and large bowel. Most appropriate initital management in this case could be

    1. Urgent exploratory laparotomy
    2. NG tube, electrolyte and fluid balance
    3. Broad spectrum Antibiotics
    4. Rectal tube and decompression

Answer.

2. 

 
Explanation.

Diagnois here is ileus. Conservative management, initially.
 

PLAB 1 Question 42021-08-06T14:31:00+01:00

PLAB 1 Question 3

Neisseria meningitidis plated on blood agar

Question.

A 67 year old retired taxi driver with a history of a previous myocardial infarction presents to the emergency department with severe abdominal pain. He complained of bloody diarrhea earlier in the day. On examination he is found to have severe generalized abdominal tenderness. His bloods shows a WCC of 20 × 109 cells/l and a lactate of 5 mmol/L. A triple phase CT shows bowel ischemia from the splenic flexure to the proximal part of the rectum. Which vessel is likely to be compromised?

    1. Superior mesenteric artery
    2. Inferior mesenteric artery
    3. Left colic artery
    4. Coeliac axis
    5. Middle colic artery

Answer.

2. 

 
Explanation.

The inferior mesenteric artery supplies the large bowel from the splenic flexure to the superior part of the rectum. The superior mesenteric artery supplies the lower part of the duodenum to the middle third of the transverse colon. The coeliac axis supplies many structures and this includes the proximal half of the duodenum. The middle colic and left colic artery are branches of the superior mesenteric artery and inferior mesenteric artery respectively.
 

PLAB 1 Question 32021-08-06T14:31:07+01:00

PLAB 1 Question 2

PLAB 1 questions

Question.

A 85 year old man is due for elective right hip arthroplasty.

What nerve is at risk of injury at the back of the hip during this procedure?

    1. Femoral Nerve
    2. Lateral cutaneous femoral nerve
    3. Sciatic nerve
    4. Pudendal Nerve
    5. Peroneal nerve

Answer.

2. 

 
Explanation.

During the posterior approach to the hip, the most predictable course of the sciatic nerve is deep to the piriformis and superficial to the short external rotators exiting above the superior gemellus at the back of the acetabulum. As such, most recommend identification of the sciatic nerve by palpation in hip replacement.

 

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PLAB 1 Question 22021-08-06T14:31:14+01:00

Core pharmacology. Is a benediction in order?

Question.

A young patient’s median nerve is injured by a supracondylor fracture of the humerus. The resulting motor deficits may include all of the following EXCEPT which one?

  1. Weakness of pronation
  2. Weakness of ulnar deviation of the wrist
  3. Loss of thumb opposition
  4. Loss of abduction of the index and middle fingers
  5. Loss of index and middle finger flexion

(more…)

Core pharmacology. Is a benediction in order?2020-11-18T16:00:32+00:00

Core Anatomy : Where does all your K+ go?

Question.

Potassium excretion by the kidney is increased by which one of the following?

  1. Aldosterone
  2. Reduced renal tubular flow
  3. Falling serum pH (acidaemia)
  4. Spironolactone
  5. ACE inhibitors

Answer.

1.

Explanation.

Potassium is readily filtered by the glomerulus with around 7-8% of this filtered potassium load ultimately excreted by the kidney. Of the remainder, the majority (70%) is re-absorbed in the proximal tubule (K+-CL- symport and K+-H+ exchanger) and a smaller amount (20%) in the ascending loop of Henle (Na+-K+-2Cl co-transporter) while the distal tubule and collecting ducts can either reabsorb or secrete potassium and are the main point of control of potassium balance.

 

Influences over the absorption or secretion of K+ in the distal tubule and collecting duct include:

  1. Aldosterone increases K+ secretion by increasing both numbers and activity of Na+/K+ ATPase in the distal tubule and collecting ducts. These reabsorb Na+ in exchange for pumping out K+ into tubular fluid. Aldosterone secretion from the adrenal cortex is stimulated by rising plasma [K+].
  2. Secretion of K+ is into tubular fluid also occurs by passive diffusion, and is therefore proportional to the flow rate of tubular fluid; increasing flow causes increased K+ secretion.
  3. A rise in serum [H+] (acidaemia) causes an increase in K+ reabsorption. The H+-K+ antiporter in the proximal tubule and H+/K+ ATPase of the intercalating cells of the collecting duct both reciprocally pump H+ out into the tubular fluid in exchange for K+ into the cell for reabsorption. Upregulation of these transporters to secrete more H+ in acid excess will cause a reciprocal increase in K+ reabsorption. This in one of the mechanisms through which metabolic acidosis and hyperkalaemia are linked.

     

Of the diuretics, the loop and thiazides will increase K+ excretion through increasing distal tubular flow rates (and both have the complication of hypokalaemia), while spironolactone increases potassium reabsorption through its effect as an aldosterone antagonist (hence known as a potassium sparing diuretic). ACE inhibitors suppress the renin-angiotensin-aldosterone system and so reduce aldosterone secretion and lead to greater potassium reabsorption.

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Core Anatomy : Where does all your K+ go?2020-11-18T15:57:52+00:00

Core Physiology: Cerebral blood flow

Question.

Which one of the following is NOT correct regarding the cerebral circulation?

  1. Cerebral oxygen consumption is about 20% of total body oxygen consumption
  2. The brain uses glucose as its main energy source
  3. Autoregulation maintains a constant cerebral blood flow for mean arterial pressures (MAP) between 60-160mmHg.
  4. Cerebral blood flow is very sensitive to arterial pO2
  5. Local metabolites, ADP, K+ and H+ ions, all increase cerebral blood flow

Answer.

4.

Explanation.

The brain is metabolically very active and under normal condition, cerebral oxygen consumption is about 20% of total body oxygen consumption.

Glucose is the source of 90% of energy of brain in normal conditions. This energy is required for maintaining electrical gradient across cell membrane and transmission of electrical impulses. Rest of energy comes from ketone bodies and other small energy metabolites but very little from fatty acids.

Cerebral blood flow is closely autoregulated and kept constant for mean arterial pressures (MAP) between around 60-150mmHg. Typically, cerebral blood flow is about 750ml per minute or round 15% of cardiac output.

Cerebral autoregulation relies on

  1. Vasomotor reflex. Increased sympathetic tone moderates blood flow through cerebral arteries at higher blood pressures
  2. Local metabolites produced when a region of brain tissue becomes more active (e.g. CO2, ADP, K+, H+) cause vasodilatation of local arterioles, thereby increasing blood flow to that region. Occurring throughout the brain this mechanism matches cerebral blood flow to demand both at the local level and for the brain as a whole.
  3. While marked hypoxia (pO2 < 6-8KPa) will stimulate cerebral arteriolar vasodilatation to increase blood flow to the brain, throughout the physiological range of arterial pO2 (8-15Kpa) cerebral arterioles are largely insensitive to oxygen. Furthermore, supplemental oxygen above this level, if anything, tends to cause vasoconstriction of cerebral arterioles and reduced blood flow.
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Core Physiology: Cerebral blood flow2020-11-18T15:55:11+00:00

Core Physiology: Gentamycin – static or synergistic?

Question.

Which one of the following is true regarding the use of gentamicin?

  1. It is bacteriostatic
  2. It has synergistic effects when used along with penicillin
  3. It is effective against anaerobes
  4. Nephrotoxicity is dose related
  5. Ototoxicity is rare

(more…)

Core Physiology: Gentamycin – static or synergistic?2018-04-13T12:04:41+01:00

Core Physiology: Laryngeal anatomy.

FRCEM primary larynx, revision question

Question.

Regarding the anatomy of the larynx, which one of the following statements is FALSE?

  1. It joins the top of the trachea at the level of C6
  2. The vocal cords lie inferior to the epiglottis
  3. The glossopharyngeal nerve (CN IX) provides both motor and sensory innervation to the larynx
  4. The vocal cords abduct during respiration but adduct during phonation
  5. The cricoid cartilage lies below the thyroid cartilage

 

 

 

 

 

 

 

 

Answer.

C

Explanation.

The anatomy of the larynx is complicated. It lies inferior to the hyoid bone, anterior to the lower pharynx and joins to the top of the trachea at C6 level.

 Three unpaired cartilages make up its external form:

(1) epiglottis (a flap of elastic cartilage covered by mucous membrane which is attached to the anterior thyroid cartilage)

(2) thyroid cartilage; and

(3) cricoid cartilage (most inferior and separated from the thyroid cartilage above by the cricothyroid membrane).

The three paired cartilages (the arytenoids, corniculate and cuneiform) are smaller, located posteriorly within the larynx, and function in movement of the vocal cords.

The extrinsic muscles of the larynx (infrahyoid, suprahyoid and stylopharangeus) move the larynx as a whole during swallowing. The intrinsic muscles (the arytenoids, cricoarytenoids, thyroarytenoids and cricothyroid) abduct, adduct, relax and tense the vocal cords during speech and respiration. The vocal cords are relaxed and abducted during respiration and adducted and tensed during phonation.

 

During swallowing the backward movement of the tongue and upward movement of the larynx forces the epiglottis down over the superior laryngeal opening to prevent swallowed matter from entering the trachea. 

The vagus nerve (CN X) provides motor and sensory innervation to the larynx via its superior laryngeal branch (motor to cricothyroid and sensory to the superior larynx above the vocal cords), and its recurrent laryngeal branch (motor to all the intrinsic muscles of the larynx except cricothyroid and sensory to the larynx below the vocal cords).

 

 

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Core Physiology: Laryngeal anatomy.2020-11-18T11:04:20+00:00

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