The pathophysiology of tremor.

Area of Science:

• Neuroscience
• Physiology

Background:

• Tremor is defined as rhythmic, involuntary oscillations of body parts.
• Four fundamental physiological mechanisms contribute to tremor: mechanical oscillations, reflex-based oscillations, central neuronal pacemakers, and disrupted feedback/feedforward loops.

Purpose of the Study:

• To explore the underlying mechanisms of various tremor types.
• To highlight advancements in understanding tremor pathophysiology.

Main Methods:

• Utilized animal models.
• Employed positron emission tomography (PET).
• Performed mathematical analysis of electromyographic (EMG) and electroencephalographic (EEG) signals.

Main Results:

• Physiological tremor involves mechanical and central components.
• Essential tremor and symptomatic palatal tremor likely originate in olivocerebellar circuits.
• Parkinson's disease rest tremor and dystonic tremor may stem from basal ganglia loops.
• Cerebellar tremor is linked to impaired cerebellar feedforward control.
• Orthostatic tremor may originate in brainstem nuclei.
• Psychogenic tremor is associated with reflex mechanisms.
• Holmes' tremor combines parkinsonian and cerebellar mechanisms.
• Neuropathic, toxic, and drug-induced tremors involve abnormal reflex pathways or various causes.

Conclusions:

• Significant progress has been made in understanding tremor pathophysiology.
• Many hypotheses require further validation with robust data.
• Developing and testing these hypotheses is crucial for advancing rational medical and surgical treatments for tremor disorders.