Review Question - QID 221225

This patient is presenting with short-stepped gait, resting tremor, and sleep disturbances, which are concerning for Parkinson disease. This disease is a clinical diagnosis that can be confirmed by physical examination.

Parkinson disease is a neurodegenerative disorder affecting the dopaminergic neurons in the basal ganglia. The primary presenting symptoms are movement impairments such as tremors, rigidity, bradykinesia (or akinesia), and postural instability. Other findings include micrographia (small handwriting), anosmia, and rapid eye movement sleep behavior disorder. Physical examination confirms the diagnosis of Parkinson disease. A dopamine uptake scan can be used, though this is not necessary and is an expensive newer technology.

Tolosa et al. review the evidence regarding the diagnosis of Parkinson disease. They discuss how there are additional diagnostic tests that can be performed if the diagnosis is unclear. They recommend evaluation by a specialized movement disorder program to make the diagnosis based on clinical presentation.

Figure/Illustration A is a histological slide of a neuron that demonstrates round eosinophilic inclusions (red circle). These Lewy bodies are composed of alpha-synuclein and are characteristically seen in Parkinson disease.

Incorrect Answers:
Answer 1: Cerebrospinal fluid tau level is not used in the evaluation of Parkinson disease. This is typically reserved for when the diagnosis of Alzheimer dementia is unclear. It is an invasive test that is not recommended in most cases.

Answer 2: MRI brain without contrast is not indicated in this instance since a physical exam is sufficient. A physical examination should be performed first to determine if there are any concerning focal signs that would warrant additional neuroimaging.

Answer 3: Olfactory testing is reserved for differentiating Parkinson disease from other Parkinson-plus syndromes, such as corticobasal degeneration. Olfactory dysfunction is common in Parkinson disease and not in Parkinson-plus syndromes.

Answer 5: Striatal dopamine transporter scan is a nuclear study that uses ioflupane-123. This test is used when the diagnosis of Parkinson disease is unclear. A low uptake of ioflupane-123 in the striatal neurons is diagnostic for Parkinson disease.

Bullet Summary:
Parkinson disease is a neurodegenerative disorder that is diagnosed based on the clinical history and physical examination.