A 76-year-old man is brought to the office by his daughter due to increasing confusion and falls. The patient was diagnosed with dementia with Lewy bodies 2 weeks ago and started on carbidopa-levodopa, risperidone, and rivastigmine for symptomatic management. Temperature is 37.2 C (99 F) and respirations are 14/min. Supine blood pressure and pulse are 129/82 mm Hg and 75/min, respectively; standing blood pressure and pulse are 101/74 mm Hg and 97/min, respectively. The patient is not oriented to place or time. Cranial nerves are intact and upper and lower limb deep tendon reflexes are 2+. Rigidity is present in both the upper and the lower extremities on passive movement and is notably worse compared with the previous examination. Which of the following is the most likely explanation for this patient's symptoms?

Question

A 76-year-old man is brought to the office by his daughter due to increasing confusion and falls.  The patient was diagnosed with dementia with Lewy bodies 2 weeks ago and started on carbidopa-levodopa, risperidone, and rivastigmine for symptomatic management.  Temperature is 37.2 C (99 F) and respirations are 14/min.  Supine blood pressure and pulse are 129/82 mm Hg and 75/min, respectively; standing blood pressure and pulse are 101/74 mm Hg and 97/min, respectively.  The patient is not oriented to place or time.  Cranial nerves are intact and upper and lower limb deep tendon reflexes are 2+.  Rigidity is present in both the upper and the lower extremities on passive movement and is notably worse compared with the previous examination.  Which of the following is the most likely explanation for this patient's symptoms?

Quizplus · Accepted Answer

Dementia with Lewy bodies (DLB) presents with dementia plus ≥2 of the following features: Visual hallucinations, parkinsonism, fluctuating cognition, and REM sleep behavior disorder. Treatments for DLB include carbidopa-levodopa for parkinsonism, cholinesterase inhibitors (eg, rivastigmine) for cognitive impairment, and melatonin for REM sleep behavior disorder. A trial of an antipsychotic medication (eg, risperidone) may be indicated in patients with functionally impairing visual hallucinations or delusions, but it must be prescribed with caution due to the extreme antipsychotic hypersensitivity of patients with DLB. Antipsychotics may be associated with worsening confusion, parkinsonism, and autonomic dysfunction when used in such patients. This patient's sudden increase in falls, confusion, orthostatic hypotension, and rigidity is most likely due to the recent prescription of risperidone, an antipsychotic known for stronger dopamine receptor antagonism relative to other second-generation antipsychotics. When antipsychotics are indicated in the treatment of DLB, evidence favors low-potency second-generation antipsychotics (eg, quetiapine). First-generation antipsychotics (eg, haloperidol) should be avoided entirely. (Choice A) Although carbidopa-levodopa may produce orthostatic hypotension and confusion, it would not explain this patient's increased rigidity. Carbidopa-levodopa and other anti-Parkinson drugs may worsen psychotic symptoms in DLB, but this risk can be minimized by cautious dose titration and as-needed use of low-potency antipsychotics. (Choice B) Postural tachycardia syndrome generally affects young women and typically causes excessive tachycardia without associated hypotension on standing. This patient's autonomic dysfunction and overall clinical picture are better explained by DLB. (Choice C) Although cognitive impairment, parkinsonism, and other symptoms may worsen over the course of DLB, the acute nature of this patient's symptom exacerbation in the context of a recent prescription of antipsychotic medication makes risperidone a better explanation for his presentation. (Choice E) Cholinesterase inhibitors (eg, rivastigmine) may be associated with diarrhea, vomiting, and bradycardia. This patient's presentation is better explained by the prescription of the antipsychotic risperidone. Educational objective: Patients with dementia with Lewy bodies (DLB) are extremely sensitive to antipsychotics, and use of this class of medication may be associated with worsening confusion, parkinsonism, and autonomic dysfunction. If DLB-associated psychotic symptoms are functionally impairing, a trial of a low-potency second-generation antipsychotic (eg, quetiapine) may be cautiously undertaken. References: Diagnosis and management of dementia with Lewy bodies: fourth consensus report of the DLB Consortium. (http://www.ncbi.nlm.nih.gov/pubmed/28592453) Diagnosis and management of cognitive and behavioral changes in dementia with Lewy bodies. (http://www.ncbi.nlm.nih.gov/pubmed/28990131)

A 76-Year-Old Man Is Brought to the Office by His