värinäön

värinäön, or vibration sense, is a somatosensory modality that allows the perception of oscillatory mechanical stimuli applied to the skin or deeper tissues. It contributes to texture discrimination and proprioceptive information about body position and movement, helping to interpret surface roughness and contact dynamics.

The sense is mediated mainly by large-diameter, myelinated Aβ afferent fibers, which convey signals from mechanoreceptors such as Pacinian corpuscles and, to a lesser extent, Meissner’s corpuscles and Ruffini endings. The afferent signals travel via the dorsal columns (fasciculus gracilis and fasciculus cuneatus) to the dorsal column–medial lemniscus pathway, thalamus, and ultimately the somatosensory cortex.

Clinically, värinäön is tested to assess peripheral nerve function and, in some contexts, dorsal column integrity. Common testing methods include applying a 128 Hz tuning fork to bony prominences (such as the big toe or ankle) and using a Rydel-Seiffer tuning fork to quantify vibration perception threshold. Värinäön tends to be affected early in distal symmetric polyneuropathies, most notably in diabetes and alcohol-related neuropathy, and can be influenced by vitamin deficiencies (e.g., B12), hypothyroidism, or aging. In contrast, some small-fiber neuropathies may spare vibration sense while affecting pain or temperature modalities.

Interpretation of results should consider age-related decline and the distribution of loss (distal vs. proximal, symmetric vs. asymmetric) to differentiate neuropathic processes from central causes. See also somatosensation, mechanoreception, and peripheral neuropathy.