Vibratory sensibility (pallesthesia) represents a temporal modulation of tactile sense. On this ground, some would argue that the elevation of vibration to a "sensory modality" is not justified. Vibratory sensibility is easily tested using a tuning fork (128 Hz). This assesses the integrity of rapidly adapting mechanoreceptors (Pacinian corpuscles) and their peripheral and central connections; the former consist of large afferent fibers, the latter of ascending projections in both the dorsal and lateral columns. The classification of both vibration and proprioception as "posterior column signs", sharing spinal cord and brainstem pathways, is common in neurological parlance (and textbooks) but questioned by some. Instances of dissociation of vibratory sensibility and proprioception are well recognized, for instance the former is usually more impaired with intramedullary myelopathies.
Decrease in sensitivity of vibratory perception (increased perceptual threshold) is the most prominent age-related finding on sensory examination, thought to reflect distal degeneration of sensory axons.
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Gilman S. Joint position sense and vibration sense. Journal ofNeurology, Neurosurgery and Psychiatry 2002; 73: 473-477