More subtle changes are assessed by:

• Two-point discrimination (2PD) This measures the distance between two prongs at which a patient can detect the difference between being touched by one or two of the prongs. The prongs can either be simply placed (static) or stroked (moving) against a finger.
• Monofilament hairs The finger is touched by a range of increasingly stiff nylon hairs. The stiffness of hair which can be first detected is recorded.

Total loss of palmar sensation is considered as a 50% functional loss of the digit affected. For example, loss of sensation in the thumb is equivalent to a 20% loss of total hand function.

Partial longitudinal loss is calculated as indicated in the figure above. This takes into account the relative importance of different sides of individual fingers. For example, the ulnar side of the little finger is more important as the hand is placed on this surface at rest. The radial side of the index finger is more important because it is used in conjunction with the thumb for opposition and pinch.

Partial transverse loss is calculated in the same way as partial amputation (see previous page).

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