8B. Parkinson’s disease

Definition and epidemiology

Parkinsonism is the clinical triad of bradykinesia, resting tremor, and rigidity. Parkinson disease (PD) is the idiopathic cause of parkinsonism when a person has parkinsonism without an underlying cause.

Etiology of parkinsonism

  • Parkinson disease
  • Drug-induced (antipsychotics)
  • Parkinson-plus syndromes
    • Multiple system atrophy
    • Lewy body dementia
    • Corticobasal degeneration
    • Progressive supranuclear palsy

Pathomechanism

There is idiopathic progressive degeneration of dopaminergic neurons in the substantia nigra, which leads to a dopamine deficiency in the CNS.

Clinical features

In Parkinson disease the symptoms are asymmetric. They have symptoms of parkinsonism, including bradykinesia, resting tremor, and rigidity, but also symptoms like hypokinetic gait, small handwriting, and postural instability.

Diagnosis and evaluation

Diagnosis is based on typical clinical features as well as ruling out secondary causes of parkinsonism with the help of MRI or scintigraphy.

Differential diagnosis

The other causes of parkinsonism have symmetric symptoms, as opposed to PD. Like the name implies, Parkinson-plus syndromes have other neurological symptoms which differentiate them. For example, Lewy body dementia has dementia and visual hallucinations, multiple system atrophy has cerebellar symptoms, etc.

Treatment

The best treatment for Parkinson disease is levodopa plus carbidopa or benserazide. Other options include dopamine antagonists, COMT inhibitors, MAO-B inhibitors, levodopa-carbidopa intestinal gel infusion (LCIG), and deep brain stimulation of subthalamic nuclei.


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9A. Peripheral facial palsy (Bell-paresis)

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