Purpose To provide the insight for postoperative hypotonia. Selective posterior rhizotomy (SPR) has been proved as a powerful tool for reducing spasticity. And also, its functional benefit and long-term effect are also well-known. Results The most considered side effect of this procedure is postoperative hypotonia. However, some extent of temporary postoperative hypotonia can be the marker of the long-term success of this procedure. While the return of spasticity is the most unwanted side effect, some kind of overfitting, temporary postoperative hypotonia, can be the solution for that. Conclusion For severely deformed patients, postoperative hypotonia may not be problematic, because severe spasticity makes them deformed and disabled. Deformed body will not show a definite disability from postoperative hypotonia.