Table 1.

Nerve Fiber Characteristics and Associated Pain.

Nerve Fiber	Conduction Speed	Diameter	Myelination	Type of Pain	Pain Characteristics
A Delta	Fast (5–30 m/s)	Medium (2–5 μm)	Myelinated	Acute pain	Sharp, pricking, or stabbing pain is often associated with acute injuries. Felt immediately following an injury and is usually localized to the area of injury. It can be described as “fast pain.”
A Beta	Very fast (33–75 m/s)	Large (5–20 μm)	Myelinated	Typically not associated with pain	Generally responsible for transmitting non-painful stimuli such as touch, pressure, and proprioception. However, in nerve injury or disease cases, they may become involved in transmitting pain signals.
C Fibers	Slow (0.5–2 m/s)	Small (0.4–1.2 μm)	Unmyelinated	Chronic pain	Dull, throbbing, aching, or burning pain is typically associated with chronic conditions. Felt a short while after an injury and can be widespread. It can be described as “slow pain”.