In a patient with vertigo, what sign or symptom would not lead to a diagnosis of viral labyrinthitis?
Correct Answer A:
Labyrinthitis is a balance disorder. It is an inflammatory process affecting the labyrinths that house the vestibular system (which sense changes in head position) of the inner ear. In addition to balance control problems, a labyrinthitis patient may encounter hearing loss and tinnitus. Labyrinthitis is caused by a virus, but it can also arise from bacterial infection, head injury, an allergy or as a reaction to a particular medicine. Both bacterial and viral labyrinthitis can cause permanent hearing loss, although this is rare. Labyrinthitis often follows an upper respiratory tract infection (URI).
When working properly, the vestibular system also relays information on head movement to the eye muscle, forming the vestibulo-ocular reflex, in order to retain continuous visual focus during motion. When the vestibular system is affected by labyrinthitis, rapid, undesired eye motion (nystagmus), often results from the improper indications of rotational motion.
Which of the following is the most sensitive method for diagnosing aortic dissection?
Aortic dissection is the surging of blood through a tear in the aortic intima with separation of the intima and media and creation of a false lumen. The intimal tear may be a primary event or secondary to hemorrhage within the media. The dissection may occur anywhere along the aorta and extend proximally or distally into other arteries.
Diagnosis is by imaging tests (eg, transesophageal echocardiography, CT angiography, MRI, contrast aortography). MRI is the gold standard test for the detection and assessment of aortic dissection, which has approximately 98% sensitivity and specificity. It is the most sensitive method for diagnosing aortic dissection and has similar specificity to CT scanning. It is a non-invasive test (does not require the use of iodinated contrast material) and can detect and quantitate the degree of aortic insufficiency.
→ Transesophageal echocardiography (TEE) has greater sensitivity (97% versus 80%) and specificity (97-100% versus 90%) than transthoracic echocardiography (TTE). TEE is as accurate as CT scanning in terms of sensitivity and specificity, and it can be used at the bedside, which makes it ideal for hemodynamically unstable patients.
→ Widening of the mediastinum on an x-ray of the chest has moderate sensitivity in the setting of an ascending aortic dissection. However, it has low specificity, as many other conditions can cause a widening of the mediastinum on chest X-ray.
Which of the following is contraindicated in an adult patient with Wolff-Parkinson-White Syndrome (WPW)?
Correct Answer D:
Wolff-Parkinson-White (WPW) syndrome is a disorder in which an extra electrical connection between the atria and the ventricles is present at birth.
Digoxin is contraindicated in patients with WPW syndrome. It may shorten the refractory period and enhance conduction over the bypass tract, which may cause an even faster tachydysrhythmia or deterioration into ventricular fibrillation.
→ The treatment of choice is direct-current cardioversion.
→ If cardioversion is not possible, drugs that prolong the refractory period of the accessory connection should be used. Examples are IV procainamide and amiodarone.
→ Adenosine is the first-line agent and is effective in approximately 90% of re-entrant narrow-complex tachycardia.
Patients with Wolff-Parkinson-White syndrome who have episodic symptomatic supraventricular tachycardia or atrial fibrillation benefit most from:
Radiofrequency catheter ablation of bypass tracts is possible in over 90% of patients and is safer and more cost effective than surgery, with a similar success rate. Intravenous and oral digoxin can shorten the refractory period of the accessory pathway, and increase the ventricular rate, causing ventricular fibrillation. Beta-blockers will not control the ventricular response during atrial fibrillation when conduction proceeds over the bypass tract.
A 43-year-old man presents 2 weeks after you see him for infectious diarrhea caused by C. jejuni. He has now developed bilateral proximal lower limb weakness and bilateral distal parasthesia and decreased ankle tendon reflex.
What is the most likely diagnosis?
Guillain-Barré syndrome is the most common acquired inflammatory neuropathy. It is an acute, usually rapidly progressive inflammatory polyneuropathy characterized by muscular weakness and mild distal sensory loss.
In most patients, the syndrome begins 1-3 weeks after an infectious disorder, surgery, or vaccination. Infection is the trigger in > 50% of patients, common pathogens include Campylobacter jejuni, enteric viruses, herpesviruses, and Mycoplasma.
Flaccid weakness predominates in most patients, it is always more prominent than sensory abnormalities and may be most prominent proximally. Relatively symmetric weakness with paresthesias usually begins in the legs and progresses to the arms, but it occasionally begins in the arms or head.
Diagnosis is clinical. If Guillain-Barré syndrome is suspected, patients should be admitted to a hospital for electromyography (EMG), CSF analysis, and measurement of forced vital capacity.
Guillain-Barré syndrome is a medical emergency, requiring constant monitoring and support of vital functions, typically in an ICU. Plasmapheresis helps when done early in the syndrome and is the treatment of choice in acutely ill patients. Immune globulin is also effective when given early.
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