Diagnostics glossary

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Tuning fork: Right ankle

The voluntary, fast conducting nerve fibres can be tested by measuring the so-called vibration perception with e.g. a tuning fork, and by determining the nerve conduction velocity (= electric conduction of nerve fibres). If the vibration perception is diminished and the nerve conduction velocity is reduced, this indicates a peripheral neuropathy.
With the tuning fork calibrated to 64 Hz according to RYDELL-SEIFFER (RYDELL-SEIFFER C64) the vibration perception is tested semi-quantitatively dorsally on various osseous points: the dorsal hallux, the medial ankle and the tibial tuberosity.
The 128Hz tuning fork is dampened to 64 Hz by adding weights. These weights are calibrated from 0 to 8/8, where 0/8 represents a strong vibration and 8/8 a very fine vibration. The patient should be relaxed and supine on the examining stretcher. First the vibrating tuning fork is placed on a point of tested intact vibration perception (e.g.the elbow). Then the patient is instructed to indicate when vibration perception disappears. By nature a coarse vibration (large amplitude) is perceived stronger.