This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

No abstract

SVS is a complication arising from excessive cerebrospinal fluid shunting after shunt surgery. It has complex pathogenesis and typical clinical symptoms. But abnormalities may not be detected on the images, resulting in misdiagnosis and missing the best time for treatment. Therefore, we cannot rely too much on imaging resources when treating such patients. We also need to make the most correct diagnosis and effective treatment based on the patient's condition and our clinical experience.

To reduce the deviations in the horizontal direction of posterior maxilla during the maxilla Le Fort I osteotomy, the authors develop and validate the precise midline positioning instrument for Le Fort I osteotomy, which can guide the precise relocation of the truncated maxillary bone segment. The patent application for the precise midline positioning instrument for Le Fort I osteotomy is already submitted (patent no: 201711245533.6, China). The accuracy of Le Fort I osteotomy can be improved significantly, because of the amplification effect of this patent on the rotation/micro-movement of the posterior maxilla in all directions to achieve the precise movement and pairing of the maxillary bone segment. And this method is simple, efficient, and laborsaving.