Spontaneous activity in peripheral sensory nerves: a systematic review

Area of Science:

• Neuroscience
• Pain Research
• Electrophysiology

Background:

• Spontaneous activity in peripheral sensory neurons is a key driver of chronic pain.
• Neuronal sensitization is the other major contributor to chronic pain states.
• The precise characteristics and temporal profile of spontaneous activity in neuropathic pain remain unclear.

Purpose of the Study:

• To systematically review and extract data on spontaneous activity in sensory neurons in neuropathic pain.
• To identify which sensory nerve fiber types exhibit spontaneous activity.
• To determine the time course of spontaneous activity in preclinical models and human subjects.

Main Methods:

• Systematic literature search and data extraction of electrophysiological studies.
• Analysis of in vivo recordings from preclinical neuropathic pain models.
• Review of microneurography recordings from human subjects with neuropathic pain.

Main Results:

• Broad agreement exists on the presence of spontaneous activity in neuropathic pain conditions, persisting for months in animals and years in humans.
• Electrophysiological methods show high variability and uncertainty in quantifying spontaneous activity.
• Limited directly controlled experiments and data comparability exist between human and animal studies.

Conclusions:

• Spontaneous peripheral neuron activity is a well-documented feature of chronic neuropathic pain.
• Significant variability and lack of direct comparability between human and animal data necessitate further research.
• Additional controlled experiments are recommended to better understand this key mechanistic feature of chronic pain.