Von Frey hair, also known as a von Frey filament or hair, is a specialized tool used in quantitative sensory testing to assess the sensitivity of the skin. It is named after the German physiologist Maximilian von Frey, who developed this method in the late 19th century.
A von Frey hair typically consists of a nylon, horsehair, or similar filament that varies in thickness and stiffness. The hair is attached to a handle and calibrated to exert specific amounts of force when applied to the skin. This allows for precise and controlled testing of sensory thresholds.
In the clinical setting, von Frey hairs are employed to measure the sensitivity of different areas of the body to mechanical pressure. The filament is gently pressed against the skin until it bends, stimulating sensory receptors underneath. The individual being tested indicates the point at which they feel the stimulus, and this pressure is recorded as a threshold measurement. Lower thresholds indicate greater sensitivity to mechanical stimuli.
Von Frey hairs are particularly useful in diagnosing and assessing conditions that involve altered sensory perception, such as neuropathies or nerve injuries. By objectively quantifying the sensory threshold, healthcare professionals can evaluate the extent of nerve damage or monitor the effectiveness of treatments over time.
Overall, von Frey hairs play a crucial role in sensory testing, allowing for precise measurement of tactile sensitivity and contributing to the understanding and management of sensory disorders.
