Snapshot A 65-year-old man present with a tremor in his right hand. His tremor is most apparent at rest and improves with movement. His movements are noticeably slower and he has difficulty initiating movement. On physical exam, the patient appears apathetic and has rigidity with passive arm movement. Gait testing is notable for shuffling with a stooped posture. Introduction Definition movement disorder characterized by bradykinesia rigidity postural instability resting tremor Parkinson-plus syndromes multiple system atrophy dysautonomia orthostatic hypotension urinary retention/incontinence early erectile dysfunction parkinsonism sleep disorders (e.g., REM sleep behavior disorder) ataxia progressive supranuclear palsy parkinsonism verticle eye movement abnormalities corticobasal degeneration (CBD) progressive asymmetric movement disorder apraxia is more suggestive of CBD Associated conditions dementia depression sleep disorders psychosis Pathogenesis Loss of dopaminergic neurons in the substantia nigra leads to dopamine depletion in the striatum this creates an imbalance between dopamine and acetylcholine resulting in improper muscle movement Impaired degradation of α-synuclein can lead to degradation of dopaminergic striatal neurons Presentation Symptoms/physical exam bradykinesia describes a slowness of movement muscle rigidity noticeable resistance to muscle movement by the examiner postural instability feeling of imbalance and having a tendency to fall a late finding in Parkinson disease secondary to loss of centrally-mediated postural reflexes resting tremor "pill rolling" is characteristic when the hand is resting the tremor improves with action Studies Clinical diagnosis Differential Huntington disease differentiating factor choreiform movements Essential tremor differentiating factor tremor is present with movement not at rest Drug-induced Parkinsonism Treatment Medical carbidopa-levodopa indication considered first-line treatment for Parkinson disease other dopamine increasing medications can be used treatment is individualized and a first-line medication is different for different patients Operative deep brain stimulation indication typically reserved for advanced Parkinson disease Complications Dementia Sleep disorders Falls