A 55-year-old man comes to the physician for excessive daytime sleepiness. Over the last year he has experienced nighttime sleep disturbances, including dream-enacting behaviors such as talking, yelling, punching, kicking, and jumping from the bed. His mood has changed and he is now frequently depressed and anxious. The patient has noticed increasing difficulty with his sense of smell and no longer enjoys a morning cup of coffee. His bowel movements have also become less regular and he is frequently constipated. He has no headaches, changes in vision, trouble swallowing, slurred speech, numbness, weakness, tremors, or difficulty walking. The patient also has no delusions or visual or auditory hallucinations. He works as an attorney and does not use tobacco, alcohol, or illicit drugs.
His temperature is 36.7 C (98 F) , blood pressure is 140/90 mm Hg, pulse is 92/min, and respirations are 12/min. Pulse oximetry shows 96% on room air. The patient's BMI is 35 kg/m². His Mini-Mental State Examination is normal. He has a diminished sense of smell on "scratch and sniff" testing.
Which of the following is the most likely explanation for this patient's symptoms?

Question

Quizplus · Accepted Answer

This patient has non-motor symptoms of early idiopathic Parkinson disease (PD). PD is uncommon in patients age <40. Certain non-motor symptoms can be seen years before the onset of motor symptoms (bradykinesia, rigidity, and tremor) and could suggest early PD. These include problems with sleep, excessive daytime somnolence, mood disturbance, anosmia, and constipation, as seen in this patient. Rapid eye movement (REM) sleep behavior disorder is seen in about 15%-47% of patients with PD and is characterized by dream-enacting behaviors such as talking, yelling, punching, kicking, and jumping from the bed. More than 75% of patients with spontaneous REM sleep behavior disorder subsequently develop PD or other alpha-synucleinopathies (eg, dementia with Lewy bodies). Depression and anxiety can also be seen in up to 50% of patients with PD and are thought to be some of the most troublesome non-motor symptoms. (Choice A) Cerebellar degeneration is characterized by gait instability, and physical findings usually include ataxia, dysmetria, dysdiadochokinesia, and intention tremor. This patient's lack of cerebellar symptoms and signs makes cerebellar degeneration unlikely. (Choice C) Hypothyroidism can cause fatigue, mood disturbance, and constipation. However, hypothyroidism is a rare cause of anosmia and is not normally associated with REM sleep behavior disorder, making the diagnosis less likely. (Choice D) Midbrain infarction can result in hypersomnolence, but patients also usually have associated oculomotor/pupillary abnormalities. (Choice E) Obstructive sleep apnea is common in men with obesity and can present with excessive daytime somnolence. However, patients also typically have respiratory-related arousal during sleep and a history of snoring, which are not evident in this patient. Educational objective: Non-motor symptoms, such as rapid eye movement sleep behavior disorder, excessive daytime somnolence, mood disturbance, anosmia, and constipation, can be suggestive of early Parkinson disease and manifest before the onset of motor symptoms. __________ References: Premotor and nonmotor features of Parkinson's disease. (http://www.ncbi.nlm.nih.gov/pubmed/24978368)

A 55-Year-Old Man Comes to the Physician for Excessive Daytime