Slow progression predicts poor prognoses in patients with spontaneous posterior interosseous nerve palsy

There are still no factors that predict the prognoses of patients with spontaneous posterior interosseous nerve palsies who are in an early phase of the illness. This paper reviewed 39 patients with this type of palsy. Seventeen patients who requested surgery for possible earlier recovery underwent interfascicular neurolysis because no signs of recovery were seen more than 3 months after onset. A Medical Research Council muscle power grade over 4 at their final visit was considered a good result, while a power less than grade 4 was considered a poor result. The clinical outcomes were significantly worse for the patients who had palsies with slow progressions (for more than 1 month) compared with those who had palsies with rapid progressions (completed within 1 month), regardless of their treatment. No significant difference was seen between the prognoses of patients with complete and incomplete palsies. We, therefore, recommend that interfascicular neurolysis is performed together with tendon transfer as the primary surgical procedures for patients with palsies with slow progression.