Figure 1.

Temporal changes in the recovery of multiple sensations after the operation. (A) Brush stroke perception. The brush stroke perception rate improved shortly after the operation. (B) Two-point discrimination. Two-point discrimination remained at a high level (>30mm) for almost 1 year postoperatively, but it then decreased and remained at a lower level. (C) Mechanical touch threshold. The threshold expressed by the von Frey monofilament gauge number improved to a level lower than the reported normal value within 1 year postoperatively. (D) Thermal perception. The thermal threshold remained at more than 50°C for 2 years postoperatively, but then improved to 50°C. Recovery to the normal range took 5 years. (E) Electric taste threshold of the tongue on the injured side. Within 1 year postoperatively, it remained high at >34dB. It subsequently began to decrease and reached the normal range 5 years postoperatively. (F) Chemical tests of the taste threshold in the tongue. Ordinates of sweet: 1, 2, 3, 4, and 5 indicate 0.3%, 2.5%, 10%, 20%, and 80% sugar solution, respectively. Ordinates of salty: 1, 2, 3, 4, and 5 indicate 0.3%, 1.25%, 5%, 10%, and 20% sodium chloride solution, respectively. Ordinates of sour: 1, 2, 3, 4, and 5 indicate 0.02%, 0.2%, 2%, 4%, and 8% tartaric acid, respectively. The three kinds of taste threshold (sweet, salty, and sour) remained high, and the patient could not detect any tastes. These tastes were detected 4 years postoperatively, and reached an almost normal level around 7 years postoperatively. (G) Presence of subjective taste sensation in daily life. Subjective recovery of taste sensation was observed 7 years after surgery.