Nathan H. Lebwohl

Nonoperative management of stable thoracolumbar burst fractures with early ambulation and bracing.

Eighteen neurologically intact patients with burst fractures at the thoracolumbar junction were treated with early ambulation in a total contact orthosis. No attempt was made to reduce the associated deformity. Selection criteria excluded patients with posterior column disruption. Hospital stay averaged 10 days. Follow-up averaged 19 months. Mean kyphosis was 19 at time of injury and 20 at follow-up. At follow-up, 15 patients rated their pain as little or none. Seventeen patients had little or no restriction of activity. Follow-up computed tomography (CT) scans obtained in eight patients showed significant resorption of retropulsed bone. No deterioration of neurologic function developed in any patient. In patients with intact posterior elements and thoracolumbar burst fractures, early mobilization in a total contact TLSO can lead to satisfactory functional results. Prolonged bed rest was not required in this series. The authors attribute the good results of nonoperative management to the exclusion of patients with posterior column disruption.

Stimulus-evoked EMG monitoring during transpedicular lumbosacral spine instrumentation. Initial clinical results.

Objectives The authors developed and evaluated an electrophysiologic method for minimizing the risk of nerve root trauma associated with the placement of pedicle screws during transpedicular lumbosacral fixation in humans. Summary of Background Data Various methods have been evaluated to reduce the high complication rates associated with lumbosacral transpedicular fixation, but none are without significant limitations or drawbacks. Using a pig model, we previously developed a technique for assessing, by electrophysiologic means, the potential risk associated with placement of a screw at a given site. In this report, the authors describe their experience with this technique in patients. Methods Electromyogram (EMG) was monitored from eight lower extremity muscles bilaterally. Square wave electrical shocks (200 μsec, 7 mA) were delivered through the instruments used to form and evaluate each pedicle hole, and through the screw itself if placement was deemed safe. Provided that the instruments used (e.g., awl, tap, probe) do not exit from bone in any direction below the entry point, the resistance of bone to the 7 mA stimulus intensity is high enough such that no nerve roots are stimulated, and the EMG traces remain flat. Conversely if EMG is evoked, it warns of a potential perforation in a pedicle wall or in the anterior body. Results The authors evaluated this technique in 18 patients in whom a total of 102 screws were placed. Based on results of electrophysiologic and palpatory evaluation, 68% of the screws were placed in a satisfactory manner. Electrophysiologic evidence of a perforation, which could not be confirmed by palpation or visulization, was seen in another 13% of this total. The remaining 19% of screw placements involved sites where a defect was missed originally by palpation alone, but was located based on electrophysiological testing combined with palpation and visualization (11%), and where a perforation was initially palpated (8%). There was no postoperative morbidity associated with malpositioned screws. Conclusion Our results indicate that the technique is sensitive and, based on early clinical results, reliable in the detection of perforations in pedicle screw placement. Moreover, the method is inexpensive, rapid, and easily implemented into a standard intraoperative monitoring protocol.

Intraoperative evoked EMG monitoring in an animal model. A new technique for evaluating pedicle screw placement.

An electric drill was used to introduce holes in the L4 through L7 pedicles in pigs. Constant-voltage stimulating pulses (5.5 V, stimulus rate = 3/sec) were delivered through a ball-tipped probe used to palpate the walls of each pedicle, and observation was made of electromyogram (EMG) evoked from hind limb muscles. Screws were placed in each pedicle hole, and evaluated for absolute voltage necessary to evoke EMG (threshold). At the conclusion of each experiment, screw positions were ascertained by removal and dissection of the lumbosacral spine. Approximately 50% of screw placements resulted in defects of the pedicle. In each of these cases, 5.5 V stimuli delivered through the probe evoked EMG from muscles innervated by adjacent motor axons. Conversely, for those cases where the pedicle was intact, significantly higher voltages were needed to evoke EMG. The authors believe that this is a promising intraoperative technique to simply and reliably identify mispositioned screws, thereby minimizing neurologic complications.

Evaluation of a training program for persons with SCI paraplegia using the Parastep 1 ambulation system: part 3. Lack of effect on bone mineral density.

OBJECTIVE To determine if the bone mineral density loss seen after spinal cord injury (SCI) is reversed by a walking program using the Parastep 1 system. DESIGN Before-after trial. SETTING Human SCI applied research laboratory. PARTICIPANTS Thirteen men and 3 women with thoracic motor- and sensory-complete SCI, mean age 28.8yrs, mean duration postinjury 3.8yrs. INTERVENTION Thirty-two functional neuromuscular stimulation (FNS) ambulation training sessions using a commercially available system (Parastep 1). This system consists of a microprocessor-controlled stimulator and a modified walking frame with finger-operated switches that permit the user to control the stimulation parameters and activate the stepping. OUTCOME MEASURE Bone mineral density at the femoral head, neck, and Wards triangle measured using a Lunar DP3 dual-photon densitometer. RESULTS No significant change in bone mineral density was found using repeated measures analyses of variance. CONCLUSIONS Axial loading combined with muscle stimulation and resistive exercise does not result in significant changes in bone mineral density in persons with complete paraplegia.

Evaluation of a training program for persons with SCI paraplegia using the Parastep 1 ambulation system: part 1. Ambulation performance and anthropometric measures.

OBJECTIVE To describe performance parameters and effects on anthropometric measures in spinal cord injured subjects training with the Parastep 1 system. DESIGN Before-after trial. SETTING Human spinal cord injury applied research laboratory. PARTICIPANTS Thirteen men and 3 women with thoracic (T4-T11) motor-complete spinal cord injury: mean age, 28.8yrs; mean duration postinjury, 3.8yrs. INTERVENTION Thirty-two functional neuromuscular stimulation ambulation training sessions using a commercially available system (Parastep-1). The hybrid system consists of a microprocessor-controlled stimulator and a modified walking frame with finger-operated switches that permit the user to control the stimulation parameters and activate the stepping. OUTCOME MEASURES Distance walked, time spent standing and walking, pace, circumferential (shoulders, chest, abdomen, waist, hips, upper arm, thigh, and calf) and skinfold (chest, triceps, axilla, subscapular, supraillium, abdomen, and thigh) measurements, body weight, thigh cross-sectional area, and calculated lean tissue. RESULTS Statistically significant changes in distance, time standing and walking, and pace were found. Increases in thigh and calf girth, thigh cross-sectional area, and calculated lean tissue, as well as a decrease in thigh skinfold measure, were all statistically significant. CONCLUSIONS The Parastep 1 system enables persons with thoracic-level spinal cord injuries to stand and ambulate short distances but with a high degree of performance variability across individuals. The factors that influence this variability have not been completely identified.

Evaluation of serum osteoblast mitogenic activity in spinal cord and head injury patients with acute heterotopic ossification

Study Design This was a blind, prospective study of the effect of sera from patients with spinal cord and head injuries on osteoblast proliferation. Objectives The authors studied whether a humoral factor that stimulates the formation of heterotopic bone is released into the circulation after a neural injury. Backgound Data Other authors have shown that a humoral osteoinductive factor may be released after head and spinal cord injuries. Methods Serum was obtained at certain times throughout the first 12 weeks post-injury and from control subjects. It was incubated with osteoblasts harvasted from fetal rats, as well as with fibroblast controls. Results There was a significant rise in serum mitogenic activity after injury in both groups. When patients that developed heterotopic ossification were compared to other patients and controls, no significant differences were seen. Conclusions This in vitro study fails to support a humoral mechanism for heterotopic ossification after spinal cord or brain injuries.

Phantom Sciatica. A Case Report

Phantom limb pain, a well known phenomenon, was described originally by Ambroise Pare in the seventeenth century. Recent investigators have described the sensation in patients who have had amputation of a limb2,5,7,8. We are aware of at least one report of a patient with a transfemoral amputation who had a herniated disc between the fifth lumbar and first sacral vertebrae that caused pain in the stump6. Although pain in a stump most often results from the formation of a neuroma6, the patient in that report became symptom-free after a laminectomy and excision of the herniated disc. In an earlier report, two patients who had had an amputation of a limb were found to have a herniated lumbar disc that caused the perception of radicular pain distal to the level of the amputation4. After excision of the lumbar disc, the radicular pain was relieved in both patients. We report on a patient who had phantom pain in the distribution of the sciatic nerve three years after a segment of that nerve had been removed in the course of an excision of an intermediate-grade liposarcoma of the posterior aspect of the right thigh. Removal of the intervertebral disc between the fourth and fifth lumbar vertebrae relieved the pain. A sixty-two-year-old woman was found to have an intermediate-grade liposarcoma in the posterior aspect of the right thigh in 1984. She was managed with one course of neoadjuvant chemotherapy, which included intra-arterial …

The Use of Modest Systemic Hypothermia After Iatrogenic Spinal Cord Injury During Surgery

Iatrogenic spinal cord injury (SCI) is an uncommon (0%-3%), yet devastating, complication of spine surgery. Recent evidence based on small clinical studies indicates that modest hypothermia is a feasible treatment option for severe SCI. We extended this treatment modality to patients with devastating iatrogenic SCI. We conducted a retrospective case series of five male patients (cervical trauma--1, cervical degenerative--2, thoracic trauma--1, and thoracic scoliosis--1) with an age range of 16-51 years (average age of 46 years) with intraoperative motor-evoked potential/somatosensory-evoked potential loss secondary to catastrophic events during the spinal operation associated with new SCI. Modest hypothermia was instituted immediately postsurgery for 24 hours. Four patients also received methylprednisolone. Preoperative American Spinal Injury Association (ASIA) scores were D (n=3) and E (n=2), while immediate postoperative scores were A (n=1), B (n=1), C (n=2), and D (n=1). Immediate postoperative MRI revealed new cord signal change in three patients. Two patients required subsequent surgery. ASIA scores at last follow-up were C (n=1), D (n=3), and E (n=1) with an improvement of 1-2 grades per patient. Adverse events such as pulmonary embolism, deep venous thrombosis, coagulopathy, or infection were not observed. Hypothermia is a feasible treatment option for patients with iatrogenic SCI. While hypothermia has not been proven to improve outcomes in these situations, aggressive medical management, including cooling, resulted in better-than-expected outcomes in this small cohort.

Vertebral body osteolysis following the use of bone morphogenetic protein in spinal surgery: A mimicker of infection

This report describes the imaging findings in three patients who developed lumbar spine osteolysis after posterior spinal fusion using rhBMP-2. These cases demonstrate the variable course of osteolysis, as well as the importance of recognizing its radiological appearances to prevent confusion with infection following spinal fusion.

Prophylactic vertebral cement augmentation at the uppermost instrumented vertebra and rostral adjacent vertebra for the prevention of proximal junctional kyphosis and failure following long-segment fusion for adult spinal deformity

BACKGROUND CONTEXT Proximal junctional kyphosis (PJK) and proximal junctional failure (PJF) are common problems after long-segment (>5 levels) thoracolumbar instrumented fusions in the treatment of adult spinal deformity (ASD). No specific surgical strategy has definitively been shown to lower the risk of PJK as the result of a multifactorial etiology. PURPOSE The study aimed to assess the incidence of PJK and PJF in patients treated with prophylactic polymethylmethacrylate (PMMA) cement augmentation at the uppermost instrumented vertebrae (UIV) and rostral adjacent vertebrae (UIV+1). STUDY DESIGN/SETTING This is a retrospective cohort-matched surgical case series at an academic institutional setting. PATIENT SAMPLE Eighty-five adult patients over a 16-year enrollment period were identified with long-segment (>5 levels) posterior thoracolumbar instrumented fusions for ASD. OUTCOME MEASURES Primary outcomes measures were PJK magnitude and PJF formation. Secondary outcomes measures were spinopelvic parameters, as well as global and regional sagittal alignment. METHODS The impact of adjunctive PMMA use in long-segment (≥5 levels) fusion for ASD was assessed in adult patients aged 18 and older. Patients were included with at least one of the following: lumbar scoliosis >20°, pelvic tilt >25°, sagittal vertical axis >5 cm, central sacral vertical line >2 cm, and thoracic kyphosis >60°. The frequency of PJF and the magnitude of PJK were measured radiographically preoperatively, postoperatively, and at maximum follow-up in controls (Group A) and PMMA at the UIV and UIV+1 (Group B). RESULTS Eighty-five patients (64±11.1 years) with ASD were identified: 47 control patients (58±10.6) and 38 patients (71±6.8) treated with PMMA at the UIV and UIV+1. The mean follow-up was 27.9 and 24.2 months in Groups A and B, respectively (p=.10). Preoperative radiographic parameters were not significantly different, except the pelvic tilt which was greater in Group A (26.6° vs. 31.4°, p=.03). Postoperatively, the lumbopelvic mismatch was greater in Group B (14.6° vs. 7.9°, p=.037), whereas the magnitude of PJK was greater in controls (9.36° vs. 5.65°, p=.023). The incidence of PJK was 36% (n=17) and 23.7% (n=9) in Groups A and B, respectively (p=.020). The odds ratio of PJK with vertebroplasty was 0.548 (95% confidence interval=0.211 to 1.424). Proximal junctional kyphosis was observed in 6 (12.8%) controls only (p=.031). The UIV+1 angle, a measure of PJK, was significantly greater in controls (10.0° vs. 6.8°, p=.02). No difference in blood loss was observed. No complications were attributed to PMMA use. CONCLUSIONS The use of prophylactic vertebral cement augmentation at the UIV and rostral adjacent vertebral segment at the time of deformity correction appears to be preventative in the development of proximal junctional kyphosis and failure.