Fascicular constrictions in patients with spontaneous palsy of the anterior interosseous nerve and the posterior interosseous nerve

There is no definition for fascicular constrictions of the spontaneous anterior interosseous nerve palsy (sAINP) and spontaneous posterior interosseous nerve palsy (sPINP). One surgeon has evaluated his findings in our 32 patients of sAINP/sPINP using either photographs or video tapes and proposed a definition. All patients had interfascicular neurolysis, and 87 case reports of "fascicular constriction" were also evaluated. Fascicular constriction was defined as every instance of thinning in the fascicle regardless to its extent. Thinning as a result of extrinsic compression was excluded. The fascicular constrictions were divided into four types: recessed, recessed-bulging, rotation, and rotation-bulging constriction. Two independent surgeons went through our findings to verify their repeatability. The relation between the fascicular constrictions and age at the onset of palsy was evaluated using Student's t test. We found 54 fascicular constrictions, with many variations. However, they could all be categorised by our method. The repeatability among the independent authors was 96%. The age at the onset of palsy was significantly younger in rotation-bulging than in rotation constriction (p = 0.0003). Our definition of describing fascicular constrictions was accurate, and should help to provide consensus in describing these palsies.