INMEDEA Simulator

Diagnostics glossary


 

Tuning fork

Synonyms: Vibratory perception, RYDELL-SEIFFER, Nerve conduction velocity, Weber's test, Rinne's test, Perceptive hearing disorders, Conduction deafness

Voluntary fast conducting nerves can be examined by measurement of the so called vibratory sense e.g. with a tuning fork and by determination of the nerve conduction velocity (= electric conduction of the nerve fibres). If the vibratory sense is reduced, and the nerve conduction velocity slowed then this is a sign of a peripheral neuropathy.
With the tuning fork dampened to 64 Hz as per Rydell-Seiffer the vibratory sense is tested semiquantitatively on various dorsal bony prominences: dorsal hallux, medial malleolus as well as the tibial tuberosity. The basal articulation of the index finger serves as reference point.
The 128 Hz tuning fork is dampened to 64 Hz with weights. It is scaled from 0 to 8/8, 0/8 means a strong vibration and 8/8 a very fine vibration. The patient should be relaxed in supine position on the examination table. The tuning fork is stroked and its base placed on a point of confirmed sensation (e.g. elbow). The patient is then asked to indicate the disappearance of any vibratory sensation. A larger amplitude is obviously perceived more intensely.
Weber-Test: By placing the vibrating tuning fork on the middle of the head or on the bony region of the forehead bone conduction is tested in side comparison.

Rinne-Test: By positioning the tuning fork on the mastoid bone conduction of the individual ear is tested, by positioning the vibrating tuning fork in front of the ear air conduction is assessed.

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