Case-based MCQ

🇨🇦 MCCQE1,2 | #Case_116 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 47-year-old female presents with progressive difficulty hearing. She is employed as an office worker, has no significant past medical history, and takes no medications. Physical examination shows no gross abnormalities of her outer ears. The external ear canals are free of cerumen, and the tympanic membranes move well to insufflation. Weber’s test and the Rinne test have results that are compatible with a conductive hearing loss. Which one of the following is the most likely cause of this patient’s hearing loss? a) Noise-induced hearing loss b) Meniere’s disease c) Otosclerosis d) Acoustic neuroma e) Perilymphatic fistula

🇨🇦 MCCQE1,2 | #Case_115 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ B 🔎 Explanation The superior division of the right middle cerebral artery (MCA) (choice B) is the most likely site of blockage in this patient. Patients with blockage of this division of MCA usually present with contralateral weakness and sensory loss on the arm and face. This division of the right MCA supplies the lateral surface of the right cerebral hemisphere above the lateral fissure but short of the superolateral portions, which are supplied by the anterior cerebral artery (ACA). Thus, motor, sensory and sensory association areas for the left upper part of the body (arm and face) are supplied by this division of MCA and weakness and sensory impairment are expected to affect these parts of the body. The lower limb is spared because its motor and sensory representation is located in the superolateral of frontal and parietal lobes which are supplied by the ACA. Because the right or non-dominant hemisphere is affected, our patient does not have any form of aphasia. ⚠ Patients with MCA blockage (choice A) usually present with symptoms and signs of blockage of its superior division (choice B), inferior division (choice C) and lenticulostriate division (choice D). Thus, these patients are expected to present with left sided weakness and hemianesthesia affecting the face, arm, and leg. Because the non-dominant right hemisphere is affect, hemi-neglect, astereognosis and anosognosia, hemianopsia rather than aphasia are also present. ⚠ Patients with inferior division of right middle cerebral artery (MCA)blockage (choice C) usually present with left sided homonymous hemianopsia because this artery supplies the parts of optic pathway that pass through the temporal lobe. Because the non-dominant hemisphere is affected, hemi-neglect, astereognosis, and anosognosia rather than aphasia accompanies the hemianopsia. ⚠ Patients with blockage of lenticulostriate branches of the right MCA(choice D) usually present with left sided hemianesthesia and hemiparesis of the leg, arm, and face. The lenticulostriate branches of the right MCA together with anterior choroidal artery supply the posterior limb of the internal capsule on the right where the motor and sensory fibers pass between the cortex and brain stem. Because motor and sensory fibers for both upper and lower parts of the body come close to each other, both of these parts of the body are affected. ⚠ Patients with right anterior cerebral artery (ACA) blockage (choice E) usually present with left sided hemianesthesia and hemiparesis of the leg. The right ACA supplies the superolateral portions of the right frontal and parietal lobes, which due homunculus topography, contains the motor and sensory areas of the lower part of the body (leg). The arms and the face are usually not affected by blockage of the ACA because cortical areas representing these parts of the body are located along the lateral surface of the cerebral hemisphere and are supplied by superior division of MCA. 🔖Key point: Weakness and anesthesia of the left arm and left half of the face and sparing of the lower leg is most likely caused by blockage in the territory of the middle cerebral artery (MCA) other than the lenticulostriate division. Absence of hemi-neglect and hemianopsia exclude blockage of the inferior division and favours blockage of the superior division of the right MCA

🇨🇦 MCCQE1,2 | #Case_115 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 50-year-old known hypertensive man was brought to the emergency department after a sudden feeling of numbness and weakness of his left arm and left half of the face. No other symptoms could be elicited and the patient could engage in dialogue, normally. Vital signs including blood pressure were stable. Left shoulder, upper arm, forearm and hand muscles have power of 2. Pain and temperature sensations are impaired on the left arm and left side of the face. No motor or sensory impairment could be detected on the right side or left lower side of the body. Visual fields were normal. The rest of physical examination was normal. Ischemic stroke was suspected. Which of the following arteries is the most likely site of blockage? a) Right middle cerebral artery b) Superior division of right middle cerebral artery c) Inferior division of right middle cerebral artery d) Lenticulostriate branches of the right middle cerebral artery e) Right anterior cerebral artery

🇨🇦 MCCQE1,2 | #Case_114 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ C 🔎 Explanation The majority of patients presenting with spontaneous pneumothorax are tall, thin individuals under 40 years of age. Most do not have clinically apparent lung disease, and the chest pain is sometimes minimal at onset and may resolve within 24 hours even if untreated. Patients with small pneumothorax involving less than 15% of the hemithorax may have a normal physical examination, although tachycardia is occasionally noted. The diagnosis is confirmed by chest radiographs. Studies of recurrence have found that an average of 30% of patients will have a recurrence within 6 months to 2 years. The treatment of an initial pneumothorax of less than 20% may be monitored if a patient has few symptoms. Follow-up should include a chest radiograph to assess stability at 24-48 hours. Indications for treatment include progression, delayed expansion, or the development of symptoms. The majority of patients with spontaneous pneumothoraces, and perhaps almost all of them, will have subpleural bullae on a CT scan.

🇨🇦 MCCQE1,2 | #Case_114 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 35-year-old male consults you about a vague chest pain he developed while sitting at his desk earlier in the day. The pain is right-sided and was sharp for a brief time when it began, but it rapidly subsided. There was no hemoptysis and the pain does not seem pleuritic. His physical examination, EKG, and oxygen saturation are unremarkable. A chest film shows a 10% right pneumothorax. Which one of the following is true in this situation? a) He is likely to be an overweight smoker with a chronic cough b) Rupture of subpleural bullae would be an unlikely cause of his problem c) Outpatient observation with a repeat chest radiograph in 24 hours is indicated d) A chest tube should be placed expeditiously e) After treatment his probability of recurrence is less than 15%

🇨🇦 MCCQE1,2 | #Case_113 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ A 🔎 Explanation Diabetic ulcers typically develop at pressure points, and the heel is a favorite location. The patient has evidence of neuropathy, and the correlation with the trauma inflicted by the new shoes is classic. Diabetic ulcers tend to occur in the following areas: -Areas most subjected to weight bearing, such as the heel, plantar metatarsal head areas, the tips of the most prominent toes (usually the first or second), and the tips of hammer toes (Ulcers also occur over the malleoli because these areas commonly are subjected to trauma.) -Areas most subjected to stress, such as the dorsal portion of hammer toes Ischemic ulcers, whether due to arteriosclerosis or embolization are typically seen at the tip of the toes, as far away from the heart as one can get.

🇨🇦 MCCQE1,2 | #Case_113 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 70 year old man has had an indolent, unhealing ulcer at the heel of the right foot for several weeks, since he started wearing his new shoes. He indicates that neither the blister nor the ulcer ever gave him any pain. The ulcer is 3.5 cm in diameter, the ulcer base looks dirty, and there is hardly any granulation tissue. The skin around the ulcer looks normal. The patient has no sensation to pin prick anywhere in that foot. Peripheral pulses are weak but palpable. He is obese and has varicose veins, high cholesterol, and poorly controlled type 2 diabetes mellitus. Which of the following most accurately characterizes the ulcer? a) Diabetic ulcer due to trauma, neuropathy, and microvascular disease b) Ischemic ulcer due to arteriosclerosis c) Ischemic ulcer due to embolization d) Neoplastic in nature, probably squamous cell carcinoma e) Stasis ulcer due to venous insufficiency

🇨🇦 MCCQE1,2 | #Case_112 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ B 🔎 Explanation When straw-colored or gray-green fluid is obtained by fine-needle aspiration of a breast nodule and the lesion completely disappears, the diagnosis is simple cyst. The fluid should not be sent for analysis because the risk for cancer is exceedingly small. If the fluid is bloody or otherwise unusual, it should be sent for cytologic examination because about 7% of bloodstained aspirates are associated with cancer

🇨🇦 MCCQE1,2 | #Case_112 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 38 year old white female presents to your office with a 4-cm palpable nodule in her right breast. Fine-needle aspiration yields 4 cc of bloody fluid. Following the aspiration, the breast nodule is no longer palpable. Which one of the following would be most appropriate at this point? a) No further workup b) Cytologic examination of the fluid c) Surgical referral for core needle biopsy d) Surgical referral for excisional biopsy e) Ultrasonography of the breast

🇨🇦 MCCQE1,2 | #Case_111 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ B 🔎 Explanation Since this patient’s wound is dirty, it would be inappropriate to fail taking prophylactic measures against tetanus, therefore choices D and E that do not include tetanus prophylaxis are incorrect. If the patient has already received tetanus booster in the last 5 years, usually the vaccine is not needed. Since this patient was last administered the tetanus toxoid 7 years ago, he should receive a shot of tetanus toxoid today (choice B). ⚠ Tetanus immune globulin (TIG) alone would not be enough prophylaxis in this patient. ⚠ Tetanus immune globulin and tetanus toxoid (choice C) would be appropriate in a patient who has not received a booster in the last 10 years. 🔖 Key point: For dirty wounds, tetanus prophylaxis should be considered as follows: If the patient has not received the tetanus booster in the last 10 years, both tetanus toxoid and tetanus immunoglobulin (TIG) are given, if the patient has received the booster in the last 10 years but not within the last 5 years, then the tetanus toxoid is given, if a patient has received the tetanus vaccine booster within the last 5 years, neither the vaccine nor the immunoglobulin are necessary

🇨🇦 MCCQE1,2 | #Case_111 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 35-year-old who was injured at his work site presents to your department with a minor wound that got dirty. The patient has no symptoms other than the bleeding he had after the injury and the pain he feels at the site of injury. He was previously healthy and has had regular check-ups and appropriate immunizations. His last tetanus booster was 7 years ago. Which of the following is the most appropriate course of action? a) Give tetanus immune globulin (TIG) b) Give tetanus toxoid alone c) Give both TIG and tetanus toxoid d) Clean the wound and give amoxicillin e) Clean wound and monitor for symptoms

🇨🇦 MCCQE1,2 | #Case_110 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ A 🔎 Explanation Cryptosporidium parvum is the most common cause of chronic diarrhea in HIV-positive patients with a CD4+ count less than 200 cells/mm³. An acid fast staining of the stool (choice A) showing oocysts is very suggestive of cryptosporidiosis. ⚠ Stool gram stain (choice E), culture an sensitivity (choice D) is very helpful for bacterial diarrheal diseases. ⚠ Colonoscopy would be warranted when inflammatory bowel diseases are suspected. ⚠ Clostridium difficile toxin assay (choice B) is the diagnostic modality of choice of pseudomembrenous colitis.

🇨🇦 MCCQE1,2 | #Case_110 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 35-year-old female presents to your office with a chronic diarrhea of 8 weeks duration. The diarrhea is associated with abdominal cramps and anorexia. She denies any blood per stool. Her past medical history is significant for HIV, diagnosed 10 years ago. Her last CD4 count, 2 months ago, was 140 cells /mm³. Which of the following tests would be the most helpful to diagnose the patient’s condition? a) Acid fast stain of the stool b) Clostridium difficile toxin assay c) Colonoscopy d) Stool culture and sensitivity e) Stool gram stain

🇨🇦 MCCQE1,2 | #Case_109 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ A 🔎 Explanation There is not a linear correlation between bone mineral density and fracture risk. Bone architecture may be changed by bisphosphonate therapy, which may result in a decreased fracture risk. This patient has not had a fracture and is on adequate medical therapy that should be continued

🇨🇦 MCCQE1,2 | #Case_109 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 70-year-old female consults you about osteoporosis treatment. Two years ago her T score was -2.6, and she began taking risedronate (Actonel), 35 mg/week. Her BMI is 24 kg/m², she takes appropriate doses of calcium and vitamin D, and she walks for at least 30 mins almost every day. Her current T score is -2.5, and she is concerned about the minimal change in spite of therapy. She has never had a fracture, but asks if more could be done to reduce her fracture risk. Which one of the following would be the most appropriate recommendation? a) Continue current treatment b) Stop risedronate and start alendronate c) Stop risedronate and start teriparatide d) Add raloxifene e) Order a bone biopsy to evaluate bone architecture

🇨🇦 MCCQE1,2 | #Case_108 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ E 🔎 Explanation The best initial therapy for Acute cardiogenic pulmonary edema includes Loop diuretics, Morphine, Nitrates and Oxygen “LMNO”. Morphine promotes venodilation thus decreases the preload; moreover, morphine alleviates the severe anxiety of acute pulmonary edema patients.

🇨🇦 MCCQE1,2 | #Case_108 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 70-year-old man presents to the ED with a severe shortness of breath and diaphoresis. His past medical history is significant for Diabetes and two previous MIs. He is taking metformin, pioglitazone, aspirin, losartan and rosuvastatin. His vitals are significant for a pulse rate of 110/min and a RR of 30/min. Physical exam shows JVD, lower limb pitting edema and bilateral basilar lung crackles. Which of the following medications is the most appropriate at this time? a) Beta-blockers b) Digoxin c) Lidocaine d) Mannitol e) Morphine

🇨🇦 MCCQE1,2 | #Case_107 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ C 🔎 Explanation This patient has athrombosed external hemorrhoid that requires immediate incision and evacuation of the clot to provide symptomatic relief.‌ Pressure by compression is usually all that is needed to control the bleeding. The typical presentation of a thrombosed external hemorrhoid is an acute onset of very severe perianal pain, particularly when walking and sitting. You know that it is an external hemorrhoid because it is below the dentate line.Acutely thrombosed external hemorrhoids may be safely excised in the emergency department in patients who present within 48-72 hours of symptom onset. In patients presenting after 72 hours from the start of symptoms, conservative medical therapy is preferable

🇨🇦 MCCQE1,2 | #Case_107 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A female patient presents with an acute onset of severe constant anal pain that has started about 2 days ago. She states that It gets worse during defecation, walking, and sitting. Physical examination and anoscopy show a tender, blue swelling below the dentate line. What is the most appropriate initial management? a) Hot bandages b) Sitz baths c) Immediate incision d) Systemic Antibiotics e) Topical Antibiotics

🇨🇦 MCCQE1,2 | #Case_107 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ C 🔎 Explanation This patient is complaining of nights sweats few hours after taking NPH and insulin aspart mix and his morning fasting glucose levels are 12.2 mmol/L (220 mg/d). Morning hyperglycemia in diabetic patients may be caused by the dawn phenomenon or the Somogyi’s effect, or simply poor glycemic control.The dawn phenomenon is associated with physiological (or pathological) decreased insulin secretion in the early morning hours, accompanied by increase of counterregulatory hormones, particularly the growth hormone. It can occur in patients with type 1 diabetes mellitus and type 2 diabetes mellitus. On the other hand, the Somogyi’s effect seems to be most associated with type 1 diabetes and its incidence is increased in young people who take NPH insulin. Hyperglycemia is usually preceded by hypoglycemia few hours earlier due to the effects of insulin treatment and this could be symptomatic or asymptomatic. This patient’s night time excessive sweating is most likely caused by hypoglycemia. It has been observed that in these patients the symptoms are not linked to the level of serum glucose itself as much as to the abrupt drop of it. A patient whose serum glucose dramatically falls from 5.6 mmol/l (100 mg/dl) to 3.3 mmol/l (60 mg/dl) in an hour is more likely to be symptomatic than a patient whose serum glucose level gradually decreases from 5.6 mmol/l (100 mg/dl) to 3.3 mmol (45 mg/dl) over 24 hours. For patients on NPH insulin treatment, hypoglycemic events can be connected with the evident peak of its concentration, taking place 4-5 hours after evening injections. The best recommendation to manage Somgyi's effect is to replace NPH insulin with a peakless long-acting analogue such as glargine or detemir (choice C). ⚠ Nocturnal hormonal measurements (choice A) have shown that patients with morning hyperglycemia have increased counterregulatory hormones, with growth hormone and glucagon being the most significant and consistent. This patient's condition is rather obvious and it's more appropriate to change from NPH insulin to long acting insulin than perform more diagnostic studies. ⚠ Reduce the evening dose of insulin by half (choice B) is incorrect. In patients treated with NPH insulin who present with hypoglycemia and Somogyi’s effect, the best treatment is switching to peakless long-acting insulin such as glargine or detemir; however, if, for some reason, NPH insulin must be used, an alternative is to subtract 2 units from 10 units and use 8 units. Studies have shown that too rapid reduction in insulin dose can cause persistent severe hyperglycemia and ketonuria. ⚠ Double the dose of NPH and insulin aspart (choice D) is incorrect. This reasoning is based on the wrong assumption, that the patient is not receiving enough insulin treatment but the symptoms of hypoglycemia he experiences in the night suggest the contrary. ⚠ No change in treatment, eat some sugar if sweating develops in the night (choice E) is incorrect. This management has been associated with even higher and longer-lasting morning hyperglycemia. 🔖Key point: Morning hyperglycemia following hypoglycemia in a type I diabetes patient treated with NPH insulin suggests Somogyi's effect. The best management is to replace the insulin therapy with long-acting insulin such as glargine or detemir