Minimally invasive lateral corpectomy for thoracolumbar traumatic burst fractures

OBJECTIVE

The need for anterior column reconstruction after thoracolumbar burst fractures remains controversial. Here, the authors present their experience with minimally invasive lateral thoracolumbar corpectomies for traumatic fractures.

METHODS

Between 2012 and 2019, 59 patients with 65 thoracolumbar fractures underwent 65 minimally invasive lateral corpectomies (MIS group). This group was compared to 16 patients with single-level thoracolumbar fractures who had undergone open lateral corpectomies with the assistance of general surgery between 2007 and 2011 (open control group). Comparisons of the two groups were made with regard to operative time, estimated blood loss, time to ambulation, and fusion rates at 1 year postoperatively. The authors further analyzed the MIS group with regard to injury mechanism, fracture characteristics, neurological outcome, and complications.

RESULTS

Patients in the MIS group had a significantly shorter mean operative time (228.3 ± 27.9 vs 255.6 ± 34.1 minutes, p = 0.001) and significantly shorter mean time to ambulation after surgery (1.8 ± 1.1 vs 5.0 ± 0.8 days, p < 0.001) than the open corpectomy group. Mean estimated blood loss did not differ significantly between the two groups, though the MIS group did trend toward a lower mean blood loss. There was no significant difference in fusion status at 1 year between the MIS and open groups; however, this comparison was limited by poor follow-up, with only 32 of 59 patients (54.2%) in the MIS group and 8 of 16 (50%) in the open group having available imaging at 1 year. Complications in the MIS group included 1 screw misplacement requiring revision, 2 postoperative femoral neuropathies (one of which improved), 1 return to surgery for inadequate posterior decompression, 4 pneumothoraces requiring chest tube placement, and 1 posterior wound infection. The rate of revision surgery for the failure of fusion in the MIS group was 1.7% (1 of 59 patients).

CONCLUSIONS

The minimally invasive lateral thoracolumbar corpectomy approach for traumatic fractures appears to be relatively safe and may result in shorter operative times and quicker mobilization as compared to those with open techniques. This should be considered as a treatment option for thoracolumbar spine fractures.

The increasing frequency of intravenous drug abuse-associated spinal epidural abscesses: a case series

OBJECTIVEFew studies have been published specifically examining intravenous drug abuse (IVDA)-associated spinal epidural abscesses (SEAs), an unfortunate sequela of the opioid crisis in the United States. Here, the authors examined a series of patients with IVDA-associated SEAs in order to shed light on this challenging disease entity.METHODSThis study is a retrospective chart review of patients presenting with IVDA-associated SEAs at the authors' institution from 2013 to 2018, spanning the statewide implementation of opioid-prescribing restrictions.RESULTSA total of 45 patients presented with IVDA-associated SEAs; 46.5% presented with a neurological deficit. Thirty-one patients underwent surgery for neurological deficit, failure of medical therapy, or both. Nineteen surgical patients underwent a fusion procedure along with decompression. The complication rate was 41.9%, and the mortality rate was 6.7%. The average length of stay was 27.6 days. Patients who underwent surgery within 24 hours of onset of neurological symptoms trended toward more improvement in their American Spinal Cord Association Impairment Scale grade than those who did not (0.5 vs -0.2, p = 0.068). Methicillin-resistant Staphylococcus aureus was isolated as the causative pathogen in 57.8% of patients. Twenty-three patients (51.5%) kept their scheduled clinic follow-up appointments. Of the fusion patients with adequate follow-up, 5 showed bony arthrodesis and 3 had pseudarthrosis. The rate of IVDA-associated SEAs increased after opioid-prescribing restrictions were put in place, from 0.54 cases per month to 1.15 cases per month (p = 0.017).CONCLUSIONSPatients with IVDA-associated SEAs are challenging to treat, with high complication rates and poor follow-up. This disease is increasing in frequency, and opioid-prescribing restrictions did not slow that rise. Community outreach to promote prevention, early medical attention, and medication compliance would benefit this largely publicly funded patient population.

Minimally Invasive Management of Civilian Gunshot Wounds to the Lumbar Spine: A Case Series and Technical Report

BACKGROUND

Treatment of penetrating gunshot wounds (GSW) to the spine remains controversial. The decision to operate is often based on surgeon preference and experience. We present a case series of 7 patients who underwent minimally invasive thoracolumbar/sacral decompression and bullet removal at a level 1 trauma center.

OBJECTIVE

To describe the use of minimally invasive techniques to achieve decompression and bullet removal for GSW to the spine.

METHODS

From 2010 to 2017, 7 patients with spinal GSW underwent minimally invasive decompression and bullet removal at an academic level 1 trauma center.

RESULTS

Patient ages ranged from 20 to 55 yr (mean: 31 yr). The mechanisms of injury were GSW to the abdomen/pelvis (n = 6) and direct GSW to the spine (n = 1). Based on the neurological examination, the injuries were characterized as complete (n = 1) or incomplete (n = 6). Decompression and bullet removal were performed using a tubular retractor system. All patients with incomplete injuries who had postdischarge follow-up demonstrated some neurologic recovery. There were no postoperative wound infections, cerebrospinal fluid (CSF) fistulas, or other complications related to the procedure.

CONCLUSION

Minimally invasive decompression and bullet removal is a safe technique that may help reduce the risk of postoperative infections and CSF fistulas in patients with GSW to the lumbar spine compared to the standard open technique. This approach appears to be particularly beneficial in patients with incomplete injuries and neuropathic pain refractory to medical treatment.

Primary pain generator identification by CT-SPECT in patients with degenerative spinal disease

OBJECTIVE

Axial spinal pain generators are difficult to identify using current diagnostic modalities. Merging CT with SPECT (CT-SPECT) scans allows for accurate identification of areas with increased osteoblastic activity, which may reflect pain generators. In this study, the authors aimed to evaluate the degree of pain improvement in patients who underwent surgery, addressing primary pain generators identified by CT-SPECT.

METHODS

The authors retrospectively reviewed all patients with chronic axial spine pain who underwent diagnostic CT-SPECT at their institution and analyzed pain improvement in those who underwent surgical treatment in order to determine whether CT-SPECT correctly identified the primary pain generator.

RESULTS

A total of 315 patients underwent diagnostic CT-SPECT between January 2014 and August 2018. Forty-eight patients underwent either cervical or lumbar fusion; there were 26 women (16 cervical, 10 lumbar) and 22 men (9 cervical, 13 lumbar). The overall axial spinal pain, as assessed through self-reporting of visual analog scale scores at 6 months postoperatively, improved from 9.04 ± 1.4 to 4.34 ± 2.3 (p = 0.026), with cervical fusion patients improving from 8.8 ± 1.8 to 3.92 ± 2.2 (p = 0.019) and lumbar fusion patients improving from 9.35 ± 0.7 to 4.87 ± 2.3 (p = 0.008).

CONCLUSIONS

CT-SPECT may offer a diagnostic advantage over current imaging modalities in identifying the primary pain generator in patients with axial spinal pain.

Change in Policy Allowing Overlapping Surgery Decreases Length of Stay in an Academic, Safety-Net Hospital

BACKGROUND

The practice of surgeons running overlapping operating rooms has recently come under scrutiny.

OBJECTIVE

To examine the impact of hospital policy allowing overlapping rooms in the case of patients admitted to a tertiary care, safety-net hospital for urgent neurosurgical procedures.

METHODS

The neurosurgery service at the hospital being studied transitioned from routinely allowing 1 room per day (period 1) to overlapping rooms (period 2), with the second room being staffed by the same attending surgeon. Patients undergoing neurosurgical intervention in each period were retrospectively compared. Demographics, indication, case type, complications, outcomes, and total charges were tracked.

RESULTS

There were 59 urgent cases in period 1 and 63 in period 2. In the case of these patients, the length of stay was significantly decreased in period 2 (13.09 d vs 19.52; P = .006). The time from admission to surgery (wait time) was also significantly decreased in period 2 (5.12 d vs 7.00; P = .04). Total charges also trended towards less in period 2 (${\$}$150 942 vs ${\$}$200 075; P = .05). Surgical complications were no different between the groups (16.9% vs 14.3%; P = .59), but medical complications were significantly decreased in period 2 (14.3% vs 30.5%; P = .009). Significantly more patients were discharged to home in period 2 (69.8% vs 42.4%; P = .003).

CONCLUSION

As a matter of policy, allowing overlapping rooms significantly reduces the length of stay in the case of a vulnerable population in need of urgent surgery at a single safety-net academic institution. This may be due to a reduction in medical complications in these patients.

Traumatic cervical spine injury during sexual activity

Sexual activity is unlikely to result in spinal injuries. We present the first case of a cervical fracture-subluxation and spinal cord injury following sexual activity. This 31-year-old female presented to the emergency room with neck pain and quadriparesis, following sexual activity in an extreme position. Imaging revealed a hyperflexion cervical fracture-subluxation injury, requiring reduction by traction, followed by circumferential surgical fixation. At 6 months postoperatively, she reported baseline return of function. This case demonstrates that sex-induced spinal injuries are possible and may require urgent surgical treatment.

A case series of penetrating spinal trauma: comparisons to blunt trauma, surgical indications, and outcomes

OBJECTIVE

While blunt spinal trauma accounts for the majority of spine trauma, penetrating injuries affect a substantial number of patients. The goal of this study was to examine the epidemiology of penetrating spine injuries compared with blunt injuries and review the operative interventions and outcomes in the penetrating spine injury group.

METHODS

The prospectively maintained trauma database was queried for spinal fractures from 2012 to 2018. Charts from patients with penetrating spine trauma were reviewed.

RESULTS

A total of 1130 patients were evaluated for traumatic spinal fractures; 154 injuries (13.6%) were secondary to penetrating injuries. Patients with penetrating injuries were significantly younger (29.2 years vs 44.1 years, p < 0.001), more likely male (87.7% vs 69.2%, p < 0.001), and more commonly African American (80.5% vs 33.3%, p < 0.05). When comparing primary insurers, the penetrating group had a significantly higher percentage of patients covered by Medicaid (60.4% vs 32.6%, p < 0.05) or prison (3.9% vs 0.1%, p < 0.05) or being uninsured (17.5% vs 10.3%, p < 0.05). The penetrating group had a higher Injury Severity Score on admission (20.2 vs 15.6, p < 0.001) and longer hospital length of stay (20.1 days vs 10.3 days, p < 0.001) and were less likely to be discharged home (51.3% vs 65.1%, p < 0.05). Of the penetrating injuries, 142 (92.2%) were due to firearms. Sixty-three patients (40.9%) with penetrating injuries had a concomitant spinal cord or cauda equina injury. Of those, 44 (69.8%) had an American Spinal Injury Association Impairment Scale (AIS) grade of A. Ten patients (15.9%) improved at least 1 AIS grade, while 2 patients (3.2%) declined at least 1 AIS grade. Nine patients with penetrating injuries underwent neurosurgical intervention: 5 for spinal instability, 4 for compressive lesions with declining neurological examination results, and 2 for infectious concerns, with some patients having multiple indications. Patients undergoing neurosurgical intervention did not show a significantly greater change in AIS grade than those who did not. No patient experienced a complication directly related to neurosurgical intervention.

CONCLUSIONS

Penetrating spinal trauma affects a younger, more publicly funded cohort than blunt spinal trauma. These patients utilize more healthcare resources and are more severely injured. Surgery is undertaken for limiting progression of neurological deficit, stabilization, or infection control.

A modified, less invasive posterior subscapular approach to the brachial plexus: case report and technical note

The traditional posterior subscapular approach offers excellent exposure of the lower brachial plexus and has been successfully used in patients with recurrent thoracic outlet syndrome after an anterior operation, brachial plexus tumors involving the proximal roots, and postirradiation brachial plexopathy, among others. However, this approach also carries some morbidity, mostly related to the extensive muscle dissection of the trapezius, rhomboids, and levator scapulae. In this article, the authors present the surgical technique and video illustration of a modified, less invasive posterior subscapular approach, using a small, self-retaining retractor and only a partial trapezius and rhomboid minor muscle dissection. This approach is likely to result in decreased postoperative morbidity and a shorter hospital stay.

Minimally invasive transforaminal lumbar interbody fusion: comparison of two techniques

BACKGROUND

Minimally invasive transforaminal lumbar interbody fusion (MI TLIF) is very popular in the United States.Two techniques are commonly used, based on either tubular or pedicle-screw-based retraction.

MATERIALS AND METHODS

Sixty patients underwent MI TLIF between 2009 and 2012, using the tubular technique (43 patients) or screw-based-retractor technique (17 patients).Perioperative parameters and 1-year outcomes were reviewed.

RESULTS

For the tubular technique, the average operative time,blood loss, and hospital stay were 189 min, 170 ml, and 3.37 days, respectively. The visual analog scale (VAS) score improved from 9.7 preoperatively to 2.6 at 1-year postoperatively. There were two incidental durotomies, none resulting in a CSF leak.There was one re-intervention for removal of a misplaced pedicle screw. For the screw-based-retractor technique, the average operative time, blood loss, and hospital stay were 223 min, 257 ml, and 3.29 days, respectively. VAS improved from 9.4 to 1.9. One patient who had an incidental durotomy developed a postoperative compressive hematoma with resultant cauda equina syndrome requiring re-intervention.There were no re-interventions for revision of instrumentation.Seven patients were lost at the 1-year visit. The fusion rate at 1-year was 100%.

CONCLUSION

Both techniques can be used with good results,but each technique offers distinct advantages and challenges that can be tailored to individual patients.

The role of nerve growth factor in neuropathic pain inhibition produced by resiniferatoxin treatment in the dorsal root ganglia

BACKGROUND

Resiniferatoxin (RTX), an excitotoxic agonist for vanilloid receptor 1, is a promising candidate for intractable pain treatment.

OBJECTIVE

We evaluated the effects of RTX, applied to dorsal root ganglia (DRG) at high doses (1200 ng), in sensory-motor function and nerve growth factor (NGF) alterations in a photochemical sciatic nerve injury rat model.

METHODS

Following RTX injection into the L3-6 DRG at high doses and behavioral evaluation, the rats were sacrificed and the DRG were tested by immunohistochemistry and mRNA analysis for NGF and its' receptors, tyrosine kinase A (TrkA) and p75. The correlation between neuropathic pain and NGF, TrkA, and p75 expression was analyzed.

RESULTS

The treated rats had preserved touch, cold, pain, and high-heat sensations, and exhibited hypoalgesia to low-heat stimulation. After RTX treatment, TrkA and p75 altered their expressions from one neuronal type to another in the DRG. NGF and p75 expression changed from the small-size neurons in neuropathic rat DRG to the large- and medium-size neurons in non-neuropathic and RTX-treated animals, concomitantly with neuropathic pain suppression. TrkA was expressed in the small-size neurons in neuropathic rat DRG, and was drastically reduced in all size neurons after RTX treatment. NGF, TrkA, and p75 mRNA expression supported these phenotypic changes in the DRG.

CONCLUSION

The pathway of NGF-TrkA expressed in the small-size neurons, associated with neuropathic pain, was shifted to the NGF-p75 pathway expressed in the large-size neurons after RTX treatment, in association with neuropathic pain inhibition. These findings may play an important role in clinical trial designs.

The effects of lumbar facet dowels on joint stiffness: a biomechanical study

BACKGROUND

Facet joint arthrosis may play a significant role in low back pain generation. The placement of facet dowels is a percutaneous treatment that aims to fuse the facets and increase joint stiffness. In this cadaveric study, we evaluated spine stiffness after facet dowel insertion in combination with several surgical procedures and determined which motions promote dowel migration.

METHODS

Six fresh frozen lumbar spines were tested in flexion-extension, lateral bending, and axial rotation. Spine stiffness was determined for the intact specimens, after L4 laminectomy, and after bilateral L4-L5 facet dowel placement, respectively. One specimen underwent a unilateral transforaminal lumbar interbody fusion (TLIF) construct and another underwent extreme lateral interbody fusion (XLIF) graft (22 mm) placement, followed by placement of facet dowels. Afterwards, the specimens were subjected to 10,000 cycles of fatigue testing in flexion-extension or axial rotation.

RESULTS

The overall decrease in stiffness after laminectomy was 4.6%. Facet dowel placement increased overall stiffness by 7.2%. The greatest increase was seen with axial rotation (13%), compared to flexion, extension, and lateral bending (9.5%, 2.3%, and 5.6%, respectively). The TLIF and XLIF plus dowel construct increased specimen stiffness to 266% and 163% of baseline, respectively. After fatigue testing, dowel migration was detected by computed tomography in the 2 uninstrumented specimens undergoing axial rotation cycling.

CONCLUSION

Facet dowels increase the stiffness of the motion segment to which they are applied and can be used in conjunction with laminectomy procedures to increase the stiffness of the joint. However, dowel migration can occur after axial rotation movements. Hybrid TLIF or XLIF plus facet dowel constructs have significantly higher stiffness than noninstrumented ones and may prevent dowel migration.

Caudal vertebral body fractures following lateral interbody fusion in nonosteoporotic patients

BACKGROUND

The minimally invasive lateral transpsoas approach for lumbar fusions has become increasingly popular. However, vertebral body fractures have been reported after this procedure, particularly in patients with osteoporosis and patients undergoing multilevel fusions. We evaluated the risk factors for caudal vertebral body fractures in 2 nonosteoporotic patients with single-level disease.

CASE REPORTS

Two patients presented with several years' history of incapacitating chronic low back pain and intermittent radicular pain. Diagnostic imaging in both cases demonstrated grade 1 degenerative spondylolisthesis. The patients underwent a lateral transpsoas interbody fusion, with lateral plate fixation in 1 patient and standalone lateral fusion in the other. The operations were performed without any incidents and both patients experienced immediate symptom relief. Both patients returned several weeks later with excruciating low back pain, without any postoperative history of trauma or heavy lifting. Diagnostic imaging in both patients showed a coronal fracture of the inferior vertebral body. The patients underwent urgent revision surgery involving posterior supplementation with pedicle screw and rod constructs and posterolateral fusion.

CONCLUSION

Caudal vertebral body fracture in patients with normal bone quality is a major potential complication after the minimally invasive lateral approach for lumbar fusions. Risk factors may include placement of a lateral plate, the size of the smaller anteroposterior cage, endplate violation, and oblique placement of the interbody cage.

Gunshot wounds to the spine in post-Katrina New Orleans

BACKGROUND

Gunshot wounds (GSW) to the spine represent a major health concern within today's society. Our study assessed the epidemiologic characteristics of patients with GSW to the spine treated in New Orleans.

PATIENTS AND METHODS

A retrospective chart review was performed from January 2007 through November 2011 on all the patients who were seen in the emergency room and diagnosed with a gunshot wound to the spine. Epidemiologic factors, as well as the results of admission toxicology screening, were noted. Outcome analysis was performed on patients undergoing conservative versus operative management for their injuries. Clinical outcomes were assessed using the ASIA classification system. Complications related to initial injury, neurosurgical procedures, and hospital stay were noted.

RESULTS

A total of 147 patients were enrolled. Of those diagnosed with a GSW to the spine, 88 (59.8%) received an admission toxicology screen. Seventy-three (83%) patients out of those tested had a positive screen, with the most common substances detected being cannabis, cocaine, and alcohol. In regards to management, 127 (87%) patients were treated conservatively and only one (0.7%) patient improved clinically from ASIA D to E. Of the 20 patients who underwent surgery, one (5%) patient had clinical improvement post-operatively from ASIA C to D.

CONCLUSIONS

This study evaluates the largest number of patients with GSW to the spine per year treated in a single centre, illustrating the violent nature of New Orleans. In this urban population, there was a clear correlation between drug use and suffering a GSW to the spine. Surgical intervention was seldom indicated in these patients and was predominately used for fixation of unstable fractures and decompression of compressive injuries, particularly below T11. Minimally invasive techniques were used successfully at our institution to minimize the risk of post-operative CSF leak.

Primary cervical spine carcinoid tumor in a woman with arm paresthesias and weakness: a case report

INTRODUCTION

Carcinoid tumors are neuroendocrine neoplasms derived from the enterochromaffin cells. Central nervous system involvement is rare and has been reported either as metastases to the brain and spine or primary tumors involving the sacrococcygeal spine. We report the first case of a primary carcinoid tumor of the cervical spine.

CASE PRESENTATION

A 50-year-old African-American woman presented with a 4-month history of numbness, paresthesias, and mild left-hand weakness. Magnetic resonance imaging of her cervical spine revealed a homogenously enhancing extradural mass, indenting the cervical cord and expanding the left neural foramen at C7-T1. A C7 corpectomy, en bloc resection of the tumor, and anterior C6-T1 fusion were performed to decompress the spinal cord and nerves and provide stability. Postoperative histopathologic examination and immunohistochemical analysis were consistent with carcinoid tumor. There has been no recurrence at the 6-year follow-up visit.

CONCLUSIONS

Primary cervical carcinoid tumor is extremely rare, but should be included in the differential diagnosis of enhancing expansile extradural masses compressing the spinal cord and nerves. Surgical resection may provide a definitive cure.

Genitofemoral Nerve Protection During the Lateral Retroperitoneal Transpsoas Approach

BACKGROUND:

The minimally invasive lateral retroperitoneal approach for lumbar fusions is a novel technique with good results, but also with significant sensory and motor complications.

OBJECTIVE:

To present the early results of a modified surgical technique, in which the psoas muscle is dissected under direct visualization.

METHODS:

Thirteen consecutive patients with L4-5 or L3-4 pathology were prospectively followed after being treated using a minimally invasive lateral approach with direct exposure of the psoas muscle before dissection. There were 7 woman and 6 men with a mean age of 52.3 years. Perioperative parameters like operative time, estimated blood loss, and length of stay, were noted. Pain, paresthesia, and motor weakness, as well as any other complications, were evaluated at 2 weeks and 3 months postoperatively.

RESULTS:

The mean operative time, estimated blood loss, and length of stay were 163 minutes, 126 mL, and 3 days, respectively. One patient exhibited anterior thigh pain and paresthesia at 2 weeks, both of which resolved by 3 months. Two patients experienced superficial wound infections that healed with antibiotics. The genitofemoral nerve was identified and protected in 7 patients; in 4 patients, it had a more posterior anatomic location than expected. The femoral nerve was not exposed or detected in the operative field by neuromonitoring, nor were there any symptoms related to a femoral nerve injury in any patient.

CONCLUSION:

Dissection of the psoas muscle under direct visualization during the minimally invasive lateral approach may provide increased safety to the genitofemoral and femoral nerves.

Neurotrophin-3 and tyrosine kinase C have modulatory effects on neuropathic pain in the rat dorsal root ganglia

BACKGROUND

Neurotrophin-3 (NT3) and its cognate receptor, tyrosine kinase C (TrkC), have recently been shown to modulate neuropathic pain. Another receptor, the transient receptor potential vanilloid 1, is considered a molecular integrator for nociception. Transient receptor potential vanilloid 1-positive cells can be selectively ablated by Resiniferatoxin (RTX). NT3 changes in the dorsal root ganglia (DRG) after RTX treatment may further define their role in pain modulation.

OBJECTIVE

To demonstrate the role of NT3 and TrkC in intraganglial RTX-induced pain suppression and in neuropathic pain development.

METHODS

Fifty-three rats underwent a photochemical left sciatic nerve injury. Neuropathic animals were treated by RTX injection in the ipsilateral L3-6 DRG. NT3 and TrkC presence in the DRG was evaluated before and after the nerve injury, as well as after RTX treatment.

RESULTS

The RTX injection resulted in pain inhibition. NT3 normally expressed mainly in large- and medium-size neurons. NT3 presence was increased mainly in the small DRG cells of neuropathic animals, and the medium- and large-size neurons of nonallodynic rats. RTX treatment of allodynic rats changed the NT3 distribution to a nonallodynic pattern. TrkC expressed mainly in large/medium-size neurons. After nerve injury, TrkC expression was also increased in the small DRG cells of allodynic animals (although less than NT3), and the medium- and large-size cells of nonallodynic ones. After RTX, TrkC expression gradually decreased, but with persistence in the large DRG cells.

CONCLUSION

NT3 may have antinociceptive effects in the DRG. These effects may be mediated, at least in part, by TrkC in the medium- and large-size DRG neurons.

Brain-derived neurotrophic factor redistribution in the dorsal root ganglia correlates with neuropathic pain inhibition after resiniferatoxin treatment

BACKGROUND CONTEXT

Brain-derived neurotrophic factor (BDNF) and its cognate receptor, the tyrosine kinase B (TrkB), are normally expressed in neurons and implicated in multiple pathological conditions. Brain-derived neurotrophic factor is produced in the central nervous system microglia in response to noxious stimuli and appear to potentiate central sensitization. Resiniferatoxin (RTX) is an excitotoxic agonist of the vanilloid receptor 1 (VR1), a cation channel protein considered an integrator for nociception. Resiniferatoxin, administered into the dorsal root ganglia (DRG), selectively eliminates the VR1-positive neurons and improves tactile allodynia in a neuropathic pain rat model.

PURPOSE

The goal of the present study was to evaluate the role of BDNF in RTX-induced neuropathic pain suppression.

STUDY DESIGN

The study design was a sciatic nerve injury animal model with intraganglionic RTX injection.

METHODS

Resiniferatoxin was injected into the DRG of the L3-L6 spinal nerves after the rats displayed tactile allodynia and thermal hyperalgesia produced by a photochemical injury to the sciatic nerve. Behavioral testing and immunohistochemical and mRNA analysis of the DRG were performed to determine BDNF's role in pain modulation.

RESULTS

Brain-derived neurotrophic factor expression in the DRG of neuropathic rats was upregulated in the small- and medium-size neurons, whereas the upregulation was observed in the large-size neurons of non-neuropathic rat DRG. A high-dose RTX injection in the DRG of neuropathic rats led to elimination of both thermal hyperalgesia and tactile allodynia and also upregulated BDNF in the large-size neurons, similar to the nonallodynic rats. Tyrosine kinase B changes mirrored the BDNF ones.

CONCLUSION

Resiniferatoxin injection in the DRG of neuropathic rats upregulates BDNF expression in the same pattern as in the large-size neurons of non-neuropathic rats. Therefore, BDNF upregulation may have pain suppressive effects. These effects are likely mediated by TrkB.

Traumatic spondyloptosis of the thoracolumbar spine

Object

Traumatic Grade V thoracolumbar spondylolisthesis, or traumatic spondyloptosis (severe translation injuries), are uncommon spinal injuries. To the best of the authors' knowledge, this article represents the first reported case series of these unique spinal lesions.

Methods

The authors undertook a retrospective review of a tertiary care regional spinal cord injury patient population treated over a 10-year period (1997–2007). They analyzed data regarding age, sex, mechanism of injury, neurological status, and treatment.

Results

Five patients were identified (3 men and 2 women) with ages ranging from 17 to 44 years. All patients had sustained high-energy closed spinal injuries: 3 motor vehicle accidents, 1 injured in a building collapse, and 1 hurt by a fallen steel beam. Four patients, all with sagittal-plane spondyloptosis, had a complete neurological deficit (American Spinal Injury Association [ASIA] Grade A), and 1, with coronal-plane spondyloptosis, presented with an incomplete neurological deficit (ASIA Grade C). Four patients had sustained concurrent multisystem trauma. All patients underwent surgery: an isolated posterior fusion in 2 and combined posterior-anterior fusion in 3. Only the patient with an incomplete neurological deficit (coronal-plane spondyloptosis) recovered neurological function postoperatively.

Conclusions

Traumatic thoracolumbar junction spondyloptosis is rare. Surgical reconstruction and stabilization allow for early mobilization and rehabilitation. In the present series, a patient with coronal-plane spondyloptosis presented with preserved neurological function. This may be due to the result of differences in resultant neurological compression due to displacement mechanics compared with sagittally displaced injuries.

The infraclavicular approach to the brachial plexus

The infraclavicular approach to the brachial plexus is commonly indicated in patients with traumatic injuries and tumors of the brachial plexus elements. We describe the anatomy and operative technique of this approach.

Vanilloid receptor 1-positive neurons mediate thermal hyperalgesia and tactile allodynia

BACKGROUND CONTEXT

The vanilloid receptor 1 (VR1) is expressed by the type II A-delta and C-fiber neurons, functioning as a molecular integrator for nociception. VR1 can be selectively ablated by resiniferatoxin (RTX), an ultra-potent excitotoxic agonist, when injected into sensory ganglia.

PURPOSE

To evaluate the role of the VR1-positive neurons in neuropathic pain.

STUDY DESIGN

Photochemical injury to rat sciatic nerve (Gazelius model).

METHODS

Two groups of rats underwent the photochemical injury and RTX treatment. RTX was injected in the dorsal root ganglia (DRGs) of the L3, L4, L5, and L6 nerve roots, either after or before the nerve injury. The animals were tested for thermal hyperalgesia (noxious heat stimuli) and mechanical allodynia (von Frey filaments). Immunohistochemical analysis of the DRGs was performed after euthanasia.

RESULTS

In the tactile allodynic rats, RTX injection in the DRGs improved the average withdrawal threshold from 1.62 g to 5.68 g. Immunohistochemical labeling showed that almost all VR1-positive neurons were eliminated. When RTX was administrated into the ipsilateral DRGs before the nerve injury, this treatment prevented the development of tactile allodynia in 12 out of 14 rats. Immunohistochemical staining revealed that the VR1-positive neurons were eliminated in the rats that did not develop tactile allodynia, whereas they were still present in the allodynic rats.

CONCLUSIONS

VR1-positive neurons are essential for the development of mechanical allodynia. In rats already exhibiting neuropathic pain, the VR1-positive neurons mediate the most sensitive part of mechanical allodynia. RTX injection in sensory ganglia may represent a novel treatment for neuropathic pain.

Anterior Supraclavicular Approach to the Brachial Plexus

The anterior supraclavicular approach to the brachial plexus is commonly indicated in patients with traumatic injuries, tumors, or entrapment of the brachial plexus elements. We describe the anatomy and operative technique of this approach, which has been used by the senior author (DGK) for the past 30 years.

Spinal intradural arteriovenous fistulas acquired in late adulthood: absent spinal venous drainage in pathogenesis and pathophysiology

✓ Intradural spinal arteriovenous fistulas (AVFs), a subtype of spinal arteriovenous malformation in which there is a direct communication between a spinal artery and a vein on the cord surface or in the subarachnoid space, are generally considered to be congenital lesions caused by maldevelopment of the embryonic vascular system. The authors present the cases of two patients with acquired AVFs of the terminal filum. In each patient an AVF between the distal segment of the anterior spinal artery and its accompanying vein on the terminal filum developed within 1 year of repeated lumbar myelography that had demonstrated no evidence of abnormal vascularity. In both patients spinal arteriography demonstrated the absence of medullary venous drainage in the thoracolumbar region, which, combined with the arterialized venous input from the AVF, permitted the development of venous congestion and myelopathy. The involved segment of the terminal filum was excised; in vitro microarteriography and the histopathological examination demonstrated a single, simple arteriovenous connection in both patients.

The findings in these cases indicate that intradural AVF can spontaneously arise in later life. The development of these lesions and/or their clinical manifestation may require not only the presence of the AVF, but also deficiency of medullary spinal venous drainage. The epidemiology and anatomy of intradural AVFs are compatible with an acquired origin in many cases.

Posterior subscapular approach to the brachial plexus

The posterior subscapular approach to the brachial plexus is commonly indicated in patients with neural entrapment (neurogenic thoracic outlet syndrome, especially when associated with a large C7 transverse process or cervical rib) and paraspinal tumors or lacerating injuries involving the spinal nerves close to the spine. This approach is also preferred in patients with previous anterior neck operations and/or morbid obesity. We describe the anatomy and operative technique of this approach, which has been used by the senior author (DGK) for the past 25 years.

Selective ablation of nociceptive neurons for elimination of hyperalgesia and neurogenic inflammation

Object

Neuropathic pain is mediated by nociceptive neurons that selectively express the vanilloid receptor 1 (VR1). Resiniferatoxin (RTX) is an excitotoxic VR1 agonist that causes destruction of VR1-positive neurons. To determine whether RTX can be used to ablate VR1-positive neurons selectively and to eliminate hyperalgesia and neurogenic inflammation without affecting tactile sensation and motor function, the authors infused it unilaterally into the trigeminal ganglia in Rhesus monkeys.

Methods

Either RTX (three animals) or vehicle (one animal) was directly infused (20 μl) into the right trigeminal ganglion in Rhesus monkeys. Animals were tested postoperatively at 1, 4, and 7 weeks thereafter for touch and pain perception in the trigeminal distribution (application of saline and capsaicin to the cornea). The number of eye blinks, eye wipes, and duration of squinting were recorded. Neurogenic inflammation was tested using capsaicin cream. Animals were killed 4 (one monkey) and 12 (three monkeys) weeks postinfusion. Histological and immunohistochemical analyses were performed.

Throughout the duration of the study, response to high-intensity pain stimulation (capsaicin) was selectively and significantly reduced (p < 0.001, RTX-treated compared with vehicle-treated eye [mean ± standard deviation]): blinks, 25.7 ± 4.4 compared with 106.6 ± 20.8; eye wipes, 1.4 ± 0.8 compared with 19.3 ± 2.5; and squinting, 1.4 ± 0.6 seconds compared with 11.4 ± 1.6 seconds. Normal response to sensation was maintained. Animals showed no neurological deficit or sign of toxicity. Neurogenic inflammation was blocked on the RTX-treated side. Immunohistochemical analysis of the RTX-treated ganglia showed selective elimination of VR1-positive neurons.

Conclusions

Nociceptive neurons can be selectively ablated by intraganglionic RTX infusion, resulting in the elimination of high-intensity pain perception and neurogenic inflammation while maintaining normal sensation and motor function. Analysis of these findings indicated that intraganglionic RTX infusion may provide a new treatment for pain syndromes such as trigeminal neuralgia as well as others.

Unilateral progressive alterations in the lumbar spine: a biomechanical study

OBJECT

Lumbar radiculopathy secondary to foraminal stenosis can be treated by unilateral removal of the overlying pars interarticularis. The main concern after this procedure is spinal stability. In this study the authors evaluate the biomechanical behavior of the lumbar spine under torsional loading after unilateral progressive alterations, including resection of the pars.

METHODS

Six human cadaveric L5-sacrum functional spinal units were tested while intact and then after the following sequential unilateral alterations: excision of the pars, capsulectomy, facetectomy, and discectomy. Specimens were tested in rotation by using a biomechanical testing machine, with an axial load of 280 N and torques of +/- 7.5 Nm. The specimens remained in the machine throughout testing, and the angular displacements were recorded after each set of trials. No statistically significant difference in any of the measured parameters was found between intact spines and those undergoing resection of the pars. For positive displacement (toward the side of the lesion), a significant difference from the intact condition was found after facetectomy and discectomy. For overall displacement (range of motion), spines treated with capsulectomy, facetectomy, and discectomy were significantly different from those in the intact condition.

CONCLUSIONS

Unilateral removal of the pars interarticularis does not increase spinal mobility in a statistically significant fashion. The clinical implication is that the spine may not become acutely unstable after unilateral resection of the pars.

Unilateral removal of pars interarticularis

OBJECT

Lumbar radiculopathy secondary to foraminal entrapment can be treated by unilateral removal of the overlying pars interarticularis. The authors prospectively evaluated the outcome after this procedure.

METHODS

Thirty-six consecutive patients underwent unilateral resection of the pars interarticularis between August 1999 and July 2002. In 18 patients acute foraminal disc herniations compressed the nerve root against the superior pedicle; in the other 18 foraminal stenosis was secondary to degenerative changes. All patients, at each visit, completed the following questionnaires: visual analog scale for overall, leg, and back pain; the Prolo Functional Economic Rating scale; and the Pain Rating Index (PRI) of the Short-Form McGill Pain Questionnaire. At 1 year, leg pain improved in 33 patients (91%). Low-back pain appeared or worsened in eight patients (22%; one in the acute herniation group and seven in the chronic degenerative group). Only one patient required lumbar fusion for pain. The Prolo economic and function scores improved in 21 (58%) and 27 (75%) patients, respectively. The PRI scores improved in 30 cases (83%). No spondylolisthesis was observed at any level at which resection had been performed.

CONCLUSIONS

Unilateral removal of the pars interarticularis is effective in relieving lumbar radicular symptoms in patients with intraforaminal entrapment. The incidence of low-back pain in patients with acute foraminal disc herniations does not increase as a result of this procedure. In patients with degenerative foraminal stenosis, unilateral resection of the pars interarticularis may be a better alternative to facetectomy and segmental fusion. This procedure may be a useful tool in spine surgery.

Selective ablation of nociceptive neurons for elimination of hyperalgesia and neurogenic inflammation

Object. Neuropathic pain is mediated by nociceptive neurons that selectively express the vanilloid receptor 1 (VR1). Resiniferatoxin (RTX) is an excitotoxic VR1 agonist that causes destruction of VR1-positive neurons. To determine whether RTX can be used to ablate VR1-positive neurons selectively and to eliminate hyperalgesia and neurogenic inflammation without affecting tactile sensation and motor function, the authors infused it unilaterally into the trigeminal ganglia in Rhesus monkeys.

Methods. Either RTX (three animals) or vehicle (one animal) was directly infused (20 µl) into the right trigeminal ganglion in Rhesus monkeys. Animals were tested postoperatively at 1, 4, and 7 weeks thereafter for touch and pain perception in the trigeminal distribution (application of saline and capsaicin to the cornea). The number of eye blinks, eye wipes, and duration of squinting were recorded. Neurogenic inflammation was tested using capsaicin cream. Animals were killed 4 (one monkey) and 12 (three monkeys) weeks postinfusion. Histological and immunohistochemical analyses were performed.

Throughout the duration of the study, response to high-intensity pain stimulation (capsaicin) was selectively and significantly reduced (p < 0.001, RTX-treated compared with vehicle-treated eye [mean ± standard deviation]): blinks, 25.7 ± 4.4 compared with 106.6 ± 20.8; eye wipes, 1.4 ± 0.8 compared with 19.3 ± 2.5; and squinting, 1.4 ± 0.6 seconds compared with 11.4 ± 1.6 seconds. Normal response to sensation was maintained. Animals showed no neurological deficit or sign of toxicity. Neurogenic inflammation was blocked on the RTX-treated side. Immunohistochemical analysis of the RTX-treated ganglia showed selective elimination of VR1-positive neurons.

Conclusions. Nociceptive neurons can be selectively ablated by intraganglionic RTX infusion, resulting in the elimination of high-intensity pain perception and neurogenic inflammation while maintaining normal sensation and motor function. Analysis of these findings indicated that intraganglionic RTX infusion may provide a new treatment for pain syndromes such as trigeminal neuralgia as well as others.

Pineal ganglioglioma in a young girl: a case report and review of the literature

Gangliogliomas are exceedingly rare in the pineal region. We present the case of a 16-year-old girl diagnosed with a pineal-region mass, initially diagnosed as a germ-cell tumor on the frozen section examination. The tumor was resected completely despite the frozen section results. The final pathological diagnosis was that of a ganglioglioma. This diagnosis obviated the need for postoperative adjuvant therapy. Gangliogliomas, although rare, should be considered in the differential diagnosis of the pineal region tumors. Frozen section results can be misleading since the large neuronal cells can mimic germ cells. Gangliogliomas are not sensitive to adjuvant therapy. Initial gross total resection should be attempted if the anatomy is favorable.

Gilliatt-Sumner Hand Revisited: A 25-year Experience

OBJECTIVE:

Thirty-three patients with true neurogenic thoracic outlet syndrome, or Gilliatt-Sumner hand, underwent surgical treatment at Louisiana State University during a 25-year period. This study retrospectively evaluated the outcome referable to pain and motor function in these patients.

METHODS:

All patients had the typical Gilliatt-Sumner hand, secondary to compression of C8, T1, and/or lower trunk. Nineteen patients underwent an anterior supraclavicular approach, and 15 patients underwent a posterior subscapular approach to the brachial plexus. Nerve action potential recordings showed plexus involvement close to the spine, at the level of the junction of the spinal nerves to the lower trunk.

RESULTS:

Pain, present in 22 patients, improved in 21. Mild motor deficit improved in 12 of 14 patients. Severe motor deficit improved partially in 14 of 20 patients.

CONCLUSION:

The diagnosis of true neurogenic thoracic outlet syndrome provides a clear operative indication. Surgical decompression needs to involve the medial portion of the plexus, and especially the spinal nerves. An anterior supraclavicular approach is preferred in most cases. If there is a large cervical rib or there has been a prior anterior operation, then a posterior subscapular approach is indicated.

Spontaneous cervical spinal epidural hematoma in a 12-year-old girl: case report and review of the literature

Spontaneous spinal epidural hematomas of the cervical spine are rare in the pediatric population. Common presentation includes neck pain and rapidly progressive quadriparesis. We report the case of a 12-year-old African-American girl with no history of trauma, who presented with a 2-day history of neck pain and cervical myelopathy. Magnetic resonance imaging revealed a spinal epidural hematoma compressing the cervical cord. Emergent surgical decompression led to complete resolution of symptoms. Spontaneous spinal epidural hematomas should be considered in the differential diagnosis of myelopathy, and, when confirmed by magnetic resonance imaging, surgical decompression should be performed on an emergent basis.

Risk stratification in mild head injury patients: the head injury predictive index

BACKGROUND

Mild Head Injury has classically been defined as patients with a Glasgow Coma Scale (GCS) of 13 to 15. While most of these patients do well, some suffer serious outcomes. The objective of this study was to identify the group at high risk for poor outcome.

METHOD

Analysis of 255 consecutive patients who presented to the Medical Center of Louisiana at New Orleans with GCS from 13 to 15 was performed. A new Head Injury Predictive Index (HIPI) based on Focal Neurological Signs, the verbal response and eye-opening components of the GCS, and CT findings was used to stratify patients into "high" and "low" risk groups.

RESULTS

There were 10 in-hospital decompensations and 7 poor outcomes at discharge. The study shows that the HIPI was predictive of both poor outcomes and in-patient decompensations.

CONCLUSION

When compared to GCS, the inclusion of computed tomographic and focal neurological data gives the HIPI more power in predicting poor outcome and in-hospital decompensations in the mild head injury group.

Vascularized temporalis muscle flap for the treatment of otorrhea. Technical note

The surgical treatment for cerebral spinal fluid (CSF) fistulas provides closure of the bone and dural defects and prevents the recurrence of brain herniation and CSF fistula. The two main approaches used are the transmastoid and middle fossa ones. The authors review the results of performing a modified middle fossa approach with a vascularized temporalis muscle flap to create a barrier between the repaired dural and bone defects. Fifteen consecutive cases of CSF fistulas treated at the authors' institution were retrospectively reviewed. All patients presented with otorrhea. Eleven patients had previously undergone ear surgery. A middle fossa approach was followed in all cases. The authors used a thin but watertight and vascularly preserved temporalis muscle flap that had been dissected from the medial side of the temporalis muscle and was laid intracranially on the floor of the middle fossa, between the repaired dura mater and petrous bone. The median follow-up period was 2.5 years. None of the patients experienced recurrence of otorrhea or meningitis. There was no complication related to the intracranial temporalis muscle flap (for example, seizures or increased intracranial pressure caused by muscle swelling). One patient developed hydrocephalus, which resolved after the placement of a ventriculoperitoneal shunt 2 months later. The thin, vascularized muscle flap created an excellent barrier against the recurrence of CSF fistulas and also avoided the risk of increased intracranial pressure caused by muscle swelling. This technique is particularly useful in refractory cases.

Gunshot wounds to the neck

Gunshot wounds to the neck are diagnostically and therapeutically challenging cases. We report such a case with vascular and neurologic injuries and describe the therapeutic options. Initial treatment is aimed at hemodynamic stabilization. Zone II neck injuries are managed selectively, and physical examination alone may dictate emergency surgical exploration. Spinal cord injury must be suspected and assessed clinically, as well as by computed tomography and angiography. Deteriorating or stable neurologic status and cord compression by bullet or bone fragments require surgical decompression. Improving neurologic status may be managed conservatively. In gunshot wounds to the neck, treatment should be individualized and multidisciplinary.