Type 1 Split Cord Malformation: The Significance of the 3D Orientation of the Bony Spur, Its Clinical Relevance, and Surgical Nuances.

Abstract

Background:Split cord malformation (SCM) remains an important cause of tethered cord syndrome. SCM type 1, wherein a bony spur separates the two dural sacs, represents a challenging condition to treat. The management can be further complicated by the other associated dysraphic states in the same patient. The bony spur at the level of split cord has been variably classified in the literature. There is, however, a paucity of literature dealing with the three-dimensional disposition of the bony spur and its clinical and operative implications.Materials and Methods:Our study included 50 patients (male/female = 24:26) of SCM type 1. The orientation of bony spur was categorized into ventral complete, ventral incomplete, and dorsal types along with simultaneous assessment of their direction in sagittal and axial planes in multiplanar computed tomography (CT) scan. Surgical plan was individualized according to each patient’s morbid anatomy.Results:The most common site of bony spur was lumbar region (n = 24). Twenty-four (48%) patients had ventral complete type spur, 19 (38%) had ventral incomplete type, and 7 (14%) had dorsal bony spur. Dorsal bony spurs presented with a greater incidence of motor symptoms (71.4%) and bladder disturbances (28.5%), whereas the ventral incomplete type of bony spur was predominantly associated with sensory symptoms (42.1%). Patients with dorsal bony spurs showed better postoperative outcomes when compared to their ventral counterparts.Conclusion:Multiplanar assessment of the bony spur using CT scan helps in surgical drilling and improves the outcome. The dorsal SCM variety showed better clinical outcomes when compared to their ventral bony spurs.