What is the primary purpose of performing percussion over the costovertebral angle during a physical examination?

Correct Answer: B

Rationale: The primary purpose of performing percussion over the costovertebral angle is to assess kidney tenderness. This technique, known as CVA tenderness, helps identify potential kidney issues such as infections or kidney stones. By tapping over this area, any tenderness or pain indicates underlying kidney pathology. This is crucial in diagnosing conditions like pyelonephritis or renal stones. The other choices are incorrect because: A: Liver enlargement is typically detected through palpation and imaging studies, not percussion over the costovertebral angle. C: Evaluating diaphragmatic excursion involves assessing the movement of the diaphragm during respiration, which is not related to percussion in the CVA region. D: Detecting fluid in the lungs is usually done through auscultation and imaging studies, not percussion over the costovertebral angle.

Correct Answer: A

Rationale: The correct answer is A: Osteoarthritis. In a 60-year-old woman with joint pain worsened with activity, improved with rest, decreased range of motion, and crepitus, osteoarthritis is the most likely diagnosis due to its characteristic presentation in weight-bearing joints. Osteoarthritis is a degenerative joint disease characterized by cartilage breakdown, leading to pain and stiffness. Rheumatoid arthritis (B) typically presents with symmetric joint involvement, morning stiffness, and systemic symptoms. Gout (C) manifests as sudden onset of severe joint pain, redness, and swelling, commonly affecting the big toe. Psoriatic arthritis (D) is associated with skin psoriasis and may involve asymmetric joint inflammation.

Correct Answer: A

Rationale: The most likely diagnosis for the 30-year-old woman with shortness of breath, dry cough, and a history of frequent sinus infections is Sarcoidosis. This is because Sarcoidosis commonly presents with respiratory symptoms such as cough and dyspnea, and can be associated with sinus involvement. Sarcoidosis is more common in younger individuals, like the patient in this case, compared to lung cancer or COPD. Pneumonia typically presents with fever and productive cough, which are not mentioned in the patient's symptoms. Chronic obstructive pulmonary disease (COPD) is more commonly seen in older individuals with a history of smoking, which is not indicated in this case. Therefore, the most likely diagnosis is Sarcoidosis based on the patient's age, symptoms, and medical history.

Correct Answer: A

Rationale: The correct answer is A: Cerebellar ataxia. Difficulty walking on toes is a sign of cerebellar dysfunction, affecting coordination and balance. The cerebellum plays a crucial role in coordinating voluntary movements, including maintaining balance and posture. In cerebellar ataxia, there is a lack of coordination in muscle movements, leading to difficulties in performing fine motor tasks like walking on toes. Peripheral neuropathy (B) primarily affects sensory and motor nerves in the limbs, causing tingling, numbness, and weakness, not specifically difficulty in walking on toes. Parkinson's disease (C) is characterized by tremors, rigidity, and bradykinesia but typically does not present with difficulty walking on toes. Stroke (D) can cause motor deficits but typically does not manifest as isolated difficulty walking on toes.

Correct Answer: C

Rationale: The correct answer is C: Cluster headache. This is because the patient's symptoms of severe one-sided headaches lasting 30 minutes to an hour, associated with eye watering and nasal congestion, are classic features of cluster headaches. These headaches are often described as excruciating and occur in clusters or cycles. Other choices can be ruled out based on the specific characteristics of the headaches described. Migraines typically last longer, tension-type headaches are usually bilateral and milder in intensity, and sinus headaches are often associated with sinus infections which the patient does not present with.