During the four year and three month period between October, 1975 and January, 1980, the author at the Department of Orthopedics, Nippon Medical School studied the post-operative results achieved in patients with digital nerve injuries.
Forty-one patients had undergone microsurgical suture in digital nerve injuries, with 57 nerves and 62 digital pulps having been operated on.
There are seven methods available for assessing the recovery of sensation after an operation. These are : the von Frey hair test, two-point discrimination test (2PD), moving two-point discrimination test (m2PD), ridge test, letter test, self-assessment test by patient and the finger volume test. With the above methods of evaluation, the results described below were obtained, allowing the following conclusions to be drawn :
1) It was possible to measure the 2PD on 50 nerves, but no 2PD measurement was possible on 12 nerves. As far as the cases of sutured nerves were concerned, 15 nerves (62.5%) out of 24 showed 2PD lower than 8 mm.
2) All the patients aged 15 years or less showed a complete recovery with a full return to normalcy.
3) Concerning those in whom it was possible to measure the 2PD response, it was found that there was a significant correlative relationship between (1) the 2PD results and von Frey hair test, (2) the 2PD results and the ridge test, (3) the 2PD results and the m2PD values, (4) the 2PD results and the finger volume test, respectively.
However, including the cases in which it was impossible to measure the 2PD, the von Frey hair test, the ridge test and the letter test were not suitable for assessing post-operative recovery of the digital nerves.
4) The finger volume test devised by the author was considered to be the only quantitave evaluation method among the techniques purporting to provide an objective assessment of sensory perception.
5) In the 2PD evaluation tests, it was possible to ascertain, though only in a small number of patients, that those patients who had shown favorable 2PD assessment results included a very few with a poor self-assessment of their recovery of sensation.
6) It is the author's contention that the recovery of the digital nerves should be assessed on the basis of an evaluation system integrating the following four test procedures : 2PD, m2 PD, patient's self-assessment and the finger volume test.