Outcomes following resection of intramedullary spinal cord cavernous malformations: a 25-year experience.

OBJECT: The management of intramedullary spinal cord cavernous malformations (CMs) is controversial. At Barrow Neurological Institute, the authors selectively offer surgical treatment for symptomatic spinal cord CMs. The purpose of this paper is to review the clinical outcomes in patients after resection of these lesions based on a single-center experience over a 25-year period. METHODS: The records of 80 patients who underwent resection of pathologically confirmed spinal cord CMs from January 1985 to May 2010 were analyzed retrospectively. Preoperative clinical status and imaging findings were evaluated as well as immediate and long-term postoperative outcomes. RESULTS: Compared with their preoperative Frankel grade, 11% of patients were worse, 83% were the same, and 6% improved immediately after surgery. At a mean follow-up interval of 5 years, 10% of patients were worse, 68% were the same, and 23% were improved compared with their preoperative status. Five percent of patients underwent reoperation for resection of a symptomatic residual or recurrent lesion. Immediate complications were encountered in 6% of patients, including CSF leakage and deep venous thrombosis. Long-term complications were encountered in 14% of patients and included kyphotic deformity, stenosis, and spinal cord tethering. A significant correlation was found between long-term outcome and anteroposterior length of the lesion (p = 0.01). CONCLUSIONS: The resection of intramedullary spinal cord CMs can be achieved with good long-term outcomes and an acceptable risk of immediate or delayed complications.

Biomechanical comparison of anterior versus posterior lumbar threaded interbody fusion cages.

STUDY DESIGN: Biomechanical flexibility tests were performed in specimens receiving anterior lumbar interbody fixation or posterior lumbar interbody fixation using dual threaded cages. OBJECTIVES: To determine differences in stability between anterior lumbar interbody fixation and posterior lumbar interbody fixation immediately after surgery and after fatigue. SUMMARY OF BACKGROUND DATA: No direct biomechanical comparison of lumbar fixation with threaded anterior lumbar interbody fixation or posterior lumbar interbody fixation cages has been performed previously. METHODS.: Sixteen anterior lumbar interbody fixation specimens and 16 posterior lumbar interbody fixation specimens underwent nondestructive biomechanical testing. Flexibility was assessed during applied flexion, extension, lateral bending, axial rotation, and anteroposterior shear before and after fixation and fatigue. After testing, specimens were dissected, and the quality of fixation was graded. RESULTS: Variability in angular range of motion after fixation was greater than normal interspecimen variability by 89% after anterior lumbar interbody fixation and by 117% after posterior lumbar interbody fixation. During flexion-extension and lateral bending, posterior lumbar interbody fixation allowed a mean of 60% smaller neutral zones than anterior lumbar interbody fixation (P < 0.05, nonpaired Student t test). During axial rotation, anterior lumbar interbody fixation allowed 15% less range of motion than posterior lumbar interbody fixation unless facets were kept intact with posterior lumbar interbody fixation (6 of 16 specimens), in which case anterior lumbar interbody fixation allowed 41% greater range of motion than posterior lumbar interbody fixation. During anteroposterior shear, both anterior lumbar interbody fixation and posterior lumbar interbody fixation restrained range of motion to within 50% of normal. Anterior lumbar interbody fixation loosened, on average, 130% more with fatigue than posterior lumbar interbody fixation during anteroposterior shear. CONCLUSIONS: Both anterior lumbar interbody fixation and posterior lumbar interbody fixation provided inconsistent stability. Therefore, stand-alone anterior lumbar interbody fixation or posterior lumbar interbody fixation may often be ineffective clinically. During all modes of loading except axial rotation, posterior lumbar interbody fixation performed slightly better than anterior lumbar interbody fixation, perhaps due to deeper hole preparation and destruction of anterior stabilizers necessary for anterior lumbar interbody fixation. Avoiding resection of facets during posterior lumbar interbody fixation led to significantly better performance during axial rotation.