Prior to administration of randomized blockade technique a pinprick test will be administered using a Neuropen on a scale of 0-1, with 1-normal sharp sensation and 0=dull change of sensation. Mechanical stimulation with pinprick testing is routinely used to test nociception in the bedside neurologic examination. Sharpness can be considered a surrogate for nociception because whereas sharpness is not necessarily painful, mechanical thresholds for sharpness closely parallel those for pain. The subject will be asked to determine whether the stimulus feels sharp. The number of grid-points with a change in sensation from baseline will be recorded at baseline and 20 minutes after the block.