Classifying Tremors Clinically

Tremor is an involuntary, rhythmic, oscillatory movement of a body part. Clinical classification is critical for diagnosis:

• Resting tremor: tremor at rest, suppressed by voluntary movement — characteristic of Parkinson's disease
• Action tremor: occurs during voluntary movement
•  — Postural: occurs while maintaining position against gravity (essential tremor)
•  — Kinetic: occurs during movement (cerebellar disorders)
•  — Intention: worsens as target is approached (cerebellar disease)

Essential tremor is the most common movement disorder, approximately 10 times more prevalent than Parkinson's disease. It is frequently misdiagnosed as Parkinson's.

Parkinson's Disease — MDS Diagnostic Criteria

Parkinson's disease (PD) is a progressive neurodegenerative disorder resulting from dopaminergic neuronal loss in the substantia nigra. The Movement Disorder Society (MDS) clinical diagnostic criteria (2015) define PD by the presence of bradykinesia PLUS at least one of: muscular rigidity, or resting tremor.

Postuma RB, et al. MDS clinical diagnostic criteria for Parkinson's disease. Mov Disord. 2015;30(12):1591–1601. doi:10.1002/mds.26424 — Gold standard diagnostic criteria for PD.

Parkinson's Disease — Common Features

• Resting tremor ("pill-rolling": 4–6 Hz)
• Bradykinesia (slowness of movement — essential feature)
• Cogwheel or lead-pipe rigidity
• Postural instability (in later stages)
• Micrographia (small handwriting)
• Hypomimia (reduced facial expression)
• Hypophonia (soft speech)
• Shuffling, festinant gait
• Non-motor: constipation, anosmia, REM sleep behaviour disorder, depression, cognitive decline

Treatment

• Levodopa/carbidopa: most effective symptomatic treatment
• Dopamine agonists (pramipexole, ropinirole, rotigotine)
• MAO-B inhibitors (rasagiline, selegiline)
• Deep Brain Stimulation (DBS): for motor fluctuations and dyskinesias uncontrolled medically
• Physiotherapy, occupational therapy, speech therapy

There is currently no disease-modifying or neuroprotective therapy proven in clinical trials. PD is not curable, though symptoms can often be well-controlled for many years.