MEDizzy - A 64-year-old man presents with symptoms of tremor and a

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A 64-year-old man presents with symptoms of tremor and a generalized feeling of slowing down. His tremor bothers him most on his left side. His past medical history is signifcant for depression, hypertension, and hyperlipidemia. He is taking fuoxetine 40 mg daily, lisinopril 40 mg daily, and atorvastatin 20 mg daily. On physical examination, he has a resting tremor with presence of cogwheel rigidity. When observing his gait, you note slow, shufing steps with difculty maneuvering to turn around. His facial features show decreased range of emotion and appear somewhat f at. Eye movements are full. Mental status examination shows normal mentation. You suspect Parkinson disease. What is your frst choice of therapy?

ExplanationThis patient exhibits classic features of PD, a diagnosis made based on clinical presentation. Historically, PD could be diagnosed if the patient had two out of three of the following: bradykinesia, tremor, and rigidity. However, given the signifcant overlap of these symptoms with atypical or secondary Parkinson syndrome, the diagnosis of PD was incorrect in about 24% of cases. More recently, it has been determined that a more predictive trio of features is rest tremor, asymmetry, and positive response to levodopa. Imaging of the brain may show reduced uptake of striatal dopaminergic markers in the posterior putamen with sparing of the caudate nucleus on positron emission tomography (PET) or single-photon emission computed tomography (SPECT) imaging. However, imaging is not required for a diagnosis of PD and is typically only performed under research settings or if there are features that would cause one to suspect an atypical Parkinson syndrome. This patient does not have features that would lead one to suspect atypical parkinsonism (Table XI-28). He also has no medications or other clinical conditions that would lead to secondary parkinsonism. The most common causes of secondary parkinsonism include stroke, tumor, infection, exposure to toxins such as carbon monoxide, and particularly medications. The medications most likely to cause secondary parkinsonism are neuroleptic agents, including metoclopramide and chlorpromazine. Treatment of PD is typically with either levodopa-carbidopa or a dopamine agonist. Levodopa has a long history of use in PD dating to the 1960s. Levodopa is administered in combination with carbidopa to prevent peripheral conversion to dopamine and thus prevent side efects, especially nausea and vomiting. In Europe, levodopa is combined with benserazide to prevent this conversion. Levodopa is the most efective symptomatic treatment of PD. It improves motor features, quality of life, and life span as well as improving productive years of life with increased independence and employability. However, the majority of patients treated with levodopa develop motor complications with “on/of” periods, referring to f uctuations in motor responsiveness to the drug. In addition, patients may develop involuntary movements as well. Further, the duration of beneft of levodopa subsides over time to where it approaches the short half-life of the drug. Nondopaminergic features, including falling, freezing, and autonomic dysfunction, are also not treated with levodopa. Many providers now prefer dopamine agonists as frst-line therapy. These drugs include pramipexole, ropinirole, and rotigotine as non–ergot derivatives. Although these agents do not show comparable efcacy compared to levodopa, they are associated with fewer motor complications. It should be noted that even with use of the dopamine agonists, eventual treatment with levodopa is required in most patients. Selegiline is a monoamine oxidase inhibitor (MAOI). Although MAOIs can be used as monotherapy in early disease, there is a risk of serotonin syndrome when used with selective serotonin reuptake inhibitor (SSRI) agents such as fuoxetine. The risk is low overall, but because this patient is untreated, there are other better options for his care.