[Diagnostic ability of power measurement of different grip forms for distal median nerve lesion]

Peripheral lesions of the median nerve cause characteristic changes of the grip function of the hand. For evaluating grip force changes, measurement by dynamometers (JAMAR dynamometer and pinch dynamometer) is of high relevance. In this study the ability of grip force measurements of different grip forms was evaluated to discriminate between a simulated median nerve lesion and healthy subjects.

In 21 healthy subjects, the grip force of power grip was measured by the JAMAR dynamometer at the second stage including measurement of force at the fingertips and the thenar by a sensor glove. With a pinch dynamometer the power of palmar abduction, precision grip, pincer grip and pinch grip was determined. Measurements were performed with and without median nerve block at the wrist.

In power grip of the JAMAR dynamometer at the second stage a significant reduction of the grip force of 13.4% was found (p < 0.03). The power distribution between the fingers D2-D5 did not change with median nerve block. The most relevant reduction of grip force in median nerve block compared with the healthy control was measured in palmar abduction (72.1%, p < 0.0002), followed by precision grip 31.0% (p < 0.0001), pincer grip 23.6% (p < 0.0004) and pinch grip 18.8% (p < 0.0002).

For the discrimination between healthy subjects and subjects with a median nerve block there was a limited relevance of the measurement of the power grip and force distribution at the fingers by the JAMAR dynamometer. However, the best distinction was observed by dynamometric measurement of other grips than power grip, such as palmar abduction, precision grip, pincer grip and pinch grip. The results could be relevant for the clinical diagnostics and rehabilitation of median nerve lesion, complementing the widespread measurement of the power grip by other grip forms.