Objective sensory disturbances

We evaluated three types of sensory disturbances: pain (surface sensation), vibration (deep sensation), and two-point discrimination (combined sensation). Two Myanmarian neurologists, two Myanmarian physicians, and a Japanese neurologist with an interpreter performed all neurological examinations. A meeting was held in advance to unify neurological examination procedures and interpretations of neurological findings.

Pain sensation was evaluated on the dorsal side of the right hand and foot, relative to the skin on the sternum, using a sharp toothpick. The neurologist repeatedly touched the dorsum of the hand or foot and the skin of the sternum, applying equal pressure, and asked about the number of touches on the skin of the hand (or foot). In this test, 10 was considered normal and 0 indicated complete sensation loss. If the average value of the hand and foot was lower than 9, the subject’s pain sensation was judged to be impaired.

Vibration sensation was evaluated on the right ulnar head and lateral malleolus, compared with the sternum, using a 128-Hz tuning fork. The neurologist vibrated the tuning fork strongly and repeatedly touched the right ulnar head (or lateral malleolus) and sternum of the participant, and asked about the number of touches on the ulnar head (or lateral malleolus). Similar to the pain sensation test, 10 was considered normal and 0 indicated complete sensation loss. If the average value of the hand and foot was lower than 9, the subject’s vibration sensation was judged to be impaired.

Two-point discrimination thresholds were evaluated using a plastic aesthesiometer device, the Touch-Test Two-point Discriminator (Baseline, USA). The palmar surface of the right index finger tip was tested. Participants kept their eyes closed and were told that one or two ends of the aesthesiometer would touch their finger in a random sequence. In each trial, the neurologist applied equal pressure for 1 s. After detecting the touch, participants had to indicate the number of points they felt, i.e., one or two. For each response, the two-point distance was increased by 1 mm. The threshold was defined as the minimum two-point distance detected by participants in three consecutive trials: 4 mm or less was judged as normal, and 5 mm or more was judged as impaired.