A 27-year-old woman comes to the office for follow-up. The patient was last seen 2 months ago due to generalized musculoskeletal pain and several months of fatigue. She was diagnosed with fibromyalgia and prescribed a low-impact exercise program and pharmacotherapy. Her pain and fatigue have improved, but she now notes intermittent episodes of "dizziness." Most of the episodes are short-lived, but she occasionally needs to brace herself against a wall or sit until the dizziness resolves. She also notes worsened lethargy and frequent dry mouth. Other medical history includes migraines and irritable bowel syndrome. The patient currently takes daily amitriptyline for fibromyalgia, occasional acetaminophen for muscular pains, and polyethylene glycol as needed for constipation. Temperature is 36.8 C (98.2 F), blood pressure is 110/70 mm Hg, pulse is 70/min, and respirations are 14/min. BMI is 21 kg/m². Mucous membranes are pink and moist, and there is no jugular venous distension. Cardiopulmonary auscultation is normal. Neurologic examination demonstrates intact cranial nerves and normal muscle strength in all extremities. Which of the following would be most helpful in determining the cause of this patient's dizziness?

Question

Quizplus · Accepted Answer

Explanation: This patient with fibromyalgia was recently initiated on amitriptyline. Amitriptyline exerts its therapeutic effects by inhibiting the reuptake of norepinephrine and serotonin, but its use is often limited due to interaction with other receptors, including: Muscarinic receptors, leading to anticholinergic symptoms (eg, dry mouth, constipation, urinary retention) Histamine receptors, leading to lethargy Alpha-adrenergic receptors, leading to orthostatic hypotension These side effects often limit treatment and result in medication discontinuation. Orthostatic hypotension is particularly common, even at low-dose therapeutic levels of amitriptyline. Manifestations may be subtle and typically include transient episodes described as "dizziness" or lightheadedness with sudden postural change, and patients often have a history of bracing themselves against a wall or sitting until the episode resolves. Diagnosis is made when orthostatic blood pressure measurement reveals a systolic blood pressure decline ≥20 mm Hg or diastolic blood pressure decline ≥10 mm Hg. Discontinuation of the medication usually resolves the symptoms. (Choice A) Carotid sinus massage can be used to diagnose/treat tachyarrhythmias (eg, paroxysmal supraventricular tachycardia). Although tachyarrhythmias can present with dizziness, most cases are also associated with palpitations and shortness of breath. (Choice B) The Dix-Hallpike maneuver can be used to diagnose benign paroxysmal positional vertigo. This condition is characterized by short episodes of vertigo with or without nausea/vomiting due to specific head movements (eg, rolling over in bed, looking up). Because this patient developed symptoms after the initiation of amitriptyline, a medication side effect is more likely. Dix-Hallpike maneuver (Choice D) Sensory ataxia is often suspected when patients have a positive Romberg test. Sensory ataxia can be associated with balance dysregulation but is not typically characterized by episodic dizziness. (Choice E) Tandem gait testing can be used to assess for cerebellar ataxia, which generally causes disequilibrium and balance issues. Patients do not typically have episodic dizziness that improves with leaning against a wall or sitting. Educational objective: Amitriptyline is commonly used for depression, insomnia, and pain disorders but is frequently associated with side effects, including orthostatic hypotension, lethargy, and anticholinergic symptoms (eg, dry mouth, constipation, urinary retention). Discontinuing the medication usually resolves these symptoms.

A 27-Year-Old Woman Comes to the Office for Follow-Up