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  • Author or Editor: James D. Lin x
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Haring J. W. Nauta, Vicki M. Soukup, Roderic H. Fabian, James T. Lin, James J. Grady, Courtney G. A. Williams, Gerald A. Campbell, Karin N. Westlund and William D. Willis Jr.

Object. This study offers clinical support for the concept that neurosurgical interruption of a midline posterior column pathway by performing a punctate midline myelotomy (PMM) provides significant pain relief without causing adverse neurological sequelae in cancer patients with visceral pain refractory to other therapies.

Methods. A PMM of the posterior columns was performed in six cancer patients in whom visceral pain had been refractory to other therapies. The cause of the visceral pain was related to residual, progressive, or recurrent local cancer or postirradiation effects. Clinical efficacy of the procedure was examined by comparing patient pain ratings and narcotic usage pre- and post-PMM. Follow-up periods ranged from 3 to 31 months. Examination of the results indicates a significant reduction in pain ratings as well as a significant reduction in daily narcotic use. No adverse neurological effects were observed. One spinal cord has been recovered for postmortem examination.

Conclusions. These findings provide corroborating clinical evidence for the existence of a newly recognized mid-line posterior column pathway that mediates the perception of visceral pelvic and abdominal pain. Preliminary data indicate that significant pain relief can be obtained following PMM with minimal neurological morbidity and suggest that the procedure may provide an alternative treatment modality for cancer-related pain in patients in whom adequate pain control with narcotics cannot be achieved or narcotic side effects cannot be tolerated.

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James D. Lin, Chao Wei, Jamal N. Shillingford, Eduardo C. Beauchamp, Lee A. Tan, Yongjung J. Kim, Ronald A. Lehman Jr. and Lawrence G. Lenke

OBJECTIVE

To demonstrate that a more ventral starting point for thoracic pedicle screw insertion, produced by aggressively removing the dorsal transverse process bone down to the superior articular facet (SAF), results in a larger margin for error and more medial screw angulation compared to the traditional dorsal starting point (DSP). The margin for error will be quantified by the maximal insertional arc (MIA).

METHODS

The study population included 10 consecutive operative patients with adult idiopathic scoliosis who underwent primary surgery. All measurements were performed using 3D visualization software by an attending spine surgeon. The screw starting points were 2 mm lateral to the midline of the SAF in the mediolateral direction and in the center of the pedicle in the cephalocaudal direction. The DSP was on the dorsal cortex. The ventral starting point (VSP) was at the depth of the SAF. Measurements included distance to the pedicle isthmus, MIA, and screw trajectories.

RESULTS

Ten patients and 110 vertebral levels (T1–11) were measured. The patients’ average age was 41.4 years (range 18–64 years). The pedicle isthmus was largest at T1 (4.04 ± 1.09 mm), and smallest at T5 (1.05 ± 0.93 mm). The distance to the pedicle isthmus was 7.47 mm for the VSP and 11.92 mm for the DSP (p < 0.001). The MIA was 15.3° for the VSP and 10.1° for the DSP (p < 0.001). Screw angulation was 21.7° for the VSP and 16.8° for the DSP (p < 0.001).

CONCLUSIONS

A more ventral starting point for thoracic pedicle screws results in increased MIA and more medial screw angulation. The increased MIA represents an increased tolerance for error that should improve the safety of pedicle screw placement. More medial screw angulation allows improved triangulation of pedicle screws.

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James D. Lin, Lee A. Tan, Chao Wei, Jamal N. Shillingford, Joseph L. Laratta, Joseph M. Lombardi, Yongjung J. Kim, Ronald A. Lehman Jr. and Lawrence G. Lenke

OBJECTIVE

The S2-alar-iliac (S2AI) screw is an increasingly popular method for spinopelvic fixation. The technique of freehand S2AI screw placement has been recently described. The purpose of this study was to demonstrate, through a CT imaging study of patients with spinal deformity, that screw trajectories based on the posterior superior iliac spine (PSIS) and sacral laminar slope result in reliable freehand S2AI trajectories that traverse safely above the sciatic notch.

METHODS

Fifty consecutive patients (age ≥ 18 years) who underwent primary spinal deformity surgery were included in the study. Simulated S2AI screw trajectories were analyzed with 3D visualization software. The cephalocaudal coordinate for the starting point was 15 mm cephalad to the PSIS. The mediolateral coordinate for the starting point was in line with the lateral border of the dorsal foramina. The cephalocaudal screw trajectory was perpendicular to the sacral laminar slope. Screw trajectories, lengths, and distance above the sciatic notch were measured.

RESULTS

The mean sagittal screw angle (cephalocaudal angulation) was 44.0° ± 8.4° and the mean transverse angle (mediolateral angulation) was 37.3° ± 4.3°. The mean starting point was 5.9 ± 5.8 mm distal to the caudal border of the S1 foramen. The mean screw length was 99.9 ± 18.6 mm. Screw trajectories were on average 8.5 ± 4.3 mm above the sciatic notch. A total of 97 of 100 screws were placed above the sciatic notch. In patients with transitional lumbosacral anatomy, the starting point on the lumbarized/sacralized side was 3.4 mm higher than on the contralateral unaffected side.

CONCLUSIONS

The PSIS and sacral laminar slope are two important anatomical landmarks for freehand S2AI screw placement.

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Griffin R. Baum, Alex S. Ha, Meghan Cerpa, Scott L. Zuckerman, James D. Lin, Richard P. Menger, Joseph A. Osorio, Simon Morr, Eric Leung, Ronald A. Lehman Jr., Zeeshan Sardar and Lawrence G. Lenke

OBJECTIVE

The goal of this study was to validate the Global Alignment and Proportion (GAP) score in a cohort of patients undergoing adult spinal deformity (ASD) surgery. The GAP score is a novel measure that uses sagittal parameters relative to each patient’s lumbosacral anatomy to predict mechanical complications after ASD surgery. External validation is required.

METHODS

Adult ASD patients undergoing > 4 levels of posterior fusion with a minimum 2-year follow-up were included. Six-week postoperative standing radiographs were used to calculate the GAP score, classified into a spinopelvic state as proportioned (P), moderately disproportioned (MD), or severely disproportioned (SD). A chi-square analysis, receiver operating characteristic curve, and Cochran-Armitage analysis were performed to assess the relationship between the GAP score and mechanical complications.

RESULTS

Sixty-seven patients with a mean age of 52.5 years (range 18–75 years) and a mean follow-up of 2.04 years were included. Patients with < 2 years of follow-up were included only if they had an early mechanical complication. Twenty of 67 patients (29.8%) had a mechanical complication. The spinopelvic state breakdown was as follows: P group, 21/67 (31.3%); MD group, 23/67 (34.3%); and SD group, 23/67 (34.3%). Mechanical complication rates were not significantly different among all groups: P group, 19.0%; MD group, 30.3%; and SD group, 39.1% (χ2 = 1.70, p = 0.19). The rates of mechanical complications between the MD and SD groups (30.4% and 39.1%) were less than those observed in the original GAP study (MD group 36.4%–57.1% and SD group 72.7%–100%). Within the P group, the rates in this study were higher than in the original study (19.0% vs 4.0%, respectively).

CONCLUSIONS

The authors found no statistically significant difference in the rate of mechanical complications between the P, MD, and SD groups. The current validation study revealed poor generalizability toward the authors’ patient population.

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Oral Presentations

2010 AANS Annual Meeting Philadelphia, Pennsylvania May 1–5, 2010