Two-Point Discrimination Test: How to Assess Hand Sensation

The Two-Point Discrimination Test is a standard neurological test used to assess sensory function, particularly in the hands and fingers. It is crucial for evaluating the extent of nerve damage and monitoring recovery.

1. Purpose

The primary purpose is to **test for** peripheral nerve function and sensory integrity. It assesses the patient's ability to distinguish between one or two separate points touching their skin. It is a key test for sensation, especially in the fingertips after a nerve injury (e.g., median or ulnar) or repair.

2. How to Perform

1. The patient is positioned in sitting, with their hand resting on a table, palm up.
2. The patient is instructed to close their eyes or look away.
3. The examiner uses a tool (like a paperclip, calipers, or a two-point discriminator) with two blunt points.
4. The examiner begins with the points wide apart and randomly touches the patient's fingertip with either ONE or TWO points.
5. The patient must state "one" or "two."
6. If the patient is correct, the examiner narrows the distance between the two points and repeats.
7. The test continues until the patient can no longer reliably distinguish two points from one. The smallest distance they can correctly identify is their "score."

3. Positive & Negative Sign

This test is not "positive" or "negative" but is measured in millimeters.

• Normal Sensation: The patient can distinguish two points that are 2-5 mm apart on the fingertips.
• Abnormal Sensation (a "Poor" sign): The patient cannot distinguish two points until they are much wider apart (e.g., >10-15 mm) or cannot distinguish them at all. This indicates a loss of sensation (paresthesia or anesthesia) in that nerve distribution.
• Comparison: The score should always be compared to the uninjured side or to established "normal" values for that body part.