Dyskinesia in Parkinson disease (PD) usually involves the neck, trunk, limbs, and face.1-3 Isolated or predominant respiratory involvement is rarely reported, and can lead to inappropriate cardiopulmonary tests and management. We report successful diagnosis and treatment of such a case for the first time using bilateral subthalamic nucleus deep brain stimulation (STN DBS).
Classification of evidence. This is a single observation without control (Class IV).Case report. A 64-year-old right-handed man with an 8-year history of PD presented with respiratory distress. His PD started with resting tremor, bradykinesia, and rigidity in his right hand, which gradually spread to the other side. His parkinsonism responded well to carbidopa/levodopa, with dosages being gradually escalated to 25/250 mg strength 1 tablet QID, until about 10 months prior to his visit, when he developed apparent respiratory distress, with involuntary rapid, strenuous, and distressful breathing (video clip 1 on the Neurology ® Web site at Neurology.org), accompanied by anxiety and mild tremor of the hands. He had these spells several times daily, lasting about 2 hours each time, leading to several emergent visits and hospitalizations for extensive workups, including EKG, stress echocardiogram, pulmonary function, and chest CT pulmonary embolism protocol, but none was revealing.After carefully checking his diary, we found that the respiratory distress started about 1 hour after 1 tablet of 25/250 mg strength carbidopa/levodopa, which lasted for 2 hours, as also confirmed by our prolonged observation in clinic. We hypothesized that his isolated respiratory distress was peak-dose respiratory dyskinesia, although we also had to rule out other possibilities, such as akathisia, given his anxiety, or nonmotor respiratory dysrhythmia.To test these hypotheses, we first added an additional tablet of 25/100 mg strength carbidopa/levodopa on each dose, which made his respiratory distress much worse, suggesting dyskinesia as the cause of his respiratory distress. We then reduced the carbidopa/ levodopa to 25/100 mg each dose, which led to complete resolution of the respiratory distress but aggravated his parkinsonism (video clip 2).We then resumed 25/250 mg carbidopa/levodopa every 6 hours QID with additional amantadine 100 mg bid, which did not improve his respiratory symptoms. We therefore reduced carbidopa/levodopa to 25/100 mg strength 2 tablets each dose with amantadine 100 mg BID, which only minimally improved his respiratory symptom, while his parkinsonism was slightly worsened.Given the fact that STN DBS could control general dyskinesia and parkinsonism and reduce the levodopa equivalent dose, 4 DBS was considered. The patient had 56% improvement on Unified Parkinson's Disease Rating Scale (UPDRS)-III score at levodopa "on" (score 20) compared to "off" state (score 45). Bilateral STN DBS was subsequently successfully placed as described elsewhere, 5 with documentation of exact lead placement using intraoperative CT fused with preoperative planning MR...
