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.

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.

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.

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

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

The Effects of Agrin Isoforms on Diabetic Neuropathic Pain in a Rat Streptozotocin Model.

BACKGROUND: Diabetes mellitus affects 9.3% of the US population and increases risks of surgery and complications. Diabetic neuropathic pain (DNP), one of the main consequences of diabetes mellitus, is extremely difficult to treat. Current medications yield limited benefits and/or have severe adverse effects. Therefore, new, effective treatment is needed. METHODS: Streptozotocin at 55 mg/kg was injected intraperitoneally in rats to induce diabetes mellitus. Diabetic rats exhibiting neuropathic pain underwent intrathecal injection of purified agrin proteins at various doses and were then tested for tactile allodynia to evaluate whether DNP was inhibited. The agrin effects were also analyzed with patch-clamp recording on spinal cord slices. RESULTS: Fifty-kilo Dalton agrin (Agr50) at 0.2 and 2 ng suppressed DNP when given intrathecally, while 25- and 75-kDa agrin (Agr25, Agr75) had little effect. The suppressive effect of Agr50 lasted 4 hours after a single bolus injection. The difference in effects of Agr50 on mean withdrawal threshold (4.6 ± 2.2 g before treatment to 26 ± 0 g after treatment) compared with that of Agr25 (4.9 ± 2.0 g to 4.9 ± 2.0 g) and Agr75 (5.3 ± 2.3 g to 9.2 ± 2.5 g) was highly significant (P < .01). On spinal cord slices, Agr50 increased spontaneous GABAergic current activities, suggesting increased spontaneous inhibitory postsynaptic currents and action potential firing rate from GABA neurons, whereas Agr25 and Agr75 had no such effect. CONCLUSIONS: Agr50 had a potent suppressive effect on DNP and increased spontaneous inhibitory postsynaptic currents and action potential firing rate from GABA neurons. Therefore, Agr50 may provide a potential therapy for DNP.

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.

A Retrospective Review of the Timing of Glasgow Coma Scale Documentation in a Trauma Database: Implications for Patient Care, Research, and Performance Metrics.

BACKGROUND: The Glasgow Coma Scale (GCS) is intended to be an objective, reliable measure of a patient's mental status. It is included as a metric for trauma registries, having implications for performance metrics and research. Our study compared the GCS recorded in the trauma registry (GCS-1) with that recorded in the neurosurgery consultation (GCS-2). METHODS: This retrospective review compared GCS-1 with GCS-2. The Trauma Injury Severity Score (TRISS) method was used to calculate probability of survival (POS) for patients using both GCS-1 and GCS-2. RESULTS: GCS-1 score significantly differed from GCS-2 score (6.69 vs. 7.84, ± 2.553; P < 0.001). There were 172 patients (37.55%) with a GCS-1 score of 3 and 87 (19.00%) with a GCS-2 score of 3 (χ2P < 0.001). The POS calculated using TRISS methodology with GCS-1 (POS-1) was 74.7% ± 26.6% compared with GCS-2 (POS-2), which was 79.3% ± 24.4%. There was a statistically significant difference in the means of POS-2 and POS-2 (P < 0.001). The actual observed survival for the cohort was 71.0% (325/458). CONCLUSIONS: The immediate GCS score recorded on patient arrival after trauma differs significantly from the GCS score recorded at later times. This finding significantly altered the probability of survival as calculated by the TRISS methodology. This situation could have profound effects on risk-adjusted benchmarking, assessments of quality of care, and injury severity stratification for research. More studies into the optimal timing of GCS score recording or changes in GCS score and their impact on survival are warranted.

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.

The Impact of Drug and Alcohol Intoxication on Glasgow Coma Scale Assessment in Patients with Traumatic Brain Injury.

BACKGROUND: The effect of intoxicating substances on assessment of Glasgow Coma Scale (GCS) in the trauma setting has not been completely elucidated. METHODS: A trauma registry was queried for patients with blunt head trauma in 2013-2017. Initial GCS score and toxicology screening from the database were reviewed. Next recorded GCS score from the neurosurgery evaluation and change in GCS score (ΔGCS) were compared. RESULTS: We reviewed 468 patients. In 217 (46.4%) patients, no toxic substances were found, whereas >1 toxic substance was found in 104 (22.2%) patients. Alcohol level above the legal limit was found in 109 (23.3%) patients, marijuana was found in 105 (22.4%) patients, benzodiazepines were found in 94 (20.1%) patients, opiates were found in 48 (10.3%) patients, and cocaine was found in 41 (8.8%) patients. Mean change in GCS score was significantly higher in impaired patients compared with patients with a negative screening test (1.74 ± 2.4 vs. 0.75 ± 2.7, P < 0.001); this is despite both groups having a similar initial GCS score (6.23 ± 3.86 in impaired group vs. 6.47 ± 3.52 in sober group, P = 0.677). Initial GCS score was 3 in 187 patients, of whom 150 had a positive toxicology screen. Change in GCS score was significantly higher in the impaired group (2.75 ± 2.7 vs. 1.19 ± 1.8, P < 0.001). CONCLUSIONS: Intoxicating substances can confound GCS assessment in trauma patients. This can have effects on patient care as well as performance metrics and predictive analytics. These patients should be screened, and intoxicating substances should be reversed or allowed to wear off before GCS score is recorded for benchmarking or quality reporting.

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.

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.

Outcomes of posterior cervical fusion and decompression: a systematic review and meta-analysis.

BACKGROUND CONTEXT: Posterior cervical fusion (PCF) with decompression is a treatment option for patients with conditions such as spondylosis, spinal stenosis, and degenerative disc disorders that result in myelopathy or radiculopathy. The annual rate, number, and cost of PCF in the United States has increased. Far fewer studies have been published on PCF outcomes than on anterior cervical fusion (ACF) outcomes, most likely because far fewer PCFs than ACFs are performed. PURPOSE: To evaluate the patient-reported and clinical outcomes of adult patients who underwent subaxial posterior cervical fusion with decompression. STUDY DESIGN/SETTING: Systematic review and meta-analysis. PATIENT SAMPLE: The total number of patients in the 31 articles reviewed and included in the meta-analysis was 1,238 (range 7-166). OUTCOME MEASURES: Preoperative to postoperative change in patient-reported outcomes (visual analog scales for arm pain and neck pain, Neck Disability Index, Japanese Orthopaedic Association [JOA] score, modified JOA score, and Nurick pain scale) and rates of fusion, revision, and complications or adverse events. METHODS: This study was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and a preapproved protocol. PubMed and Embase databases were searched for articles published from January 2001 through July 2018. Statistical analyses for patient-reported outcomes were performed on the outcomes' raw mean differences, calculated as postoperative value minus preoperative value from each study. Pooled rates of successful fusion, revision surgery, and complications or adverse events, and their 95% confidence intervals, were also calculated. Two subgroup analyses were performed: one for studies in which only myelopathy or radiculopathy (or both) were stated as surgical indications and the other for studies in which only myelopathy or ossification of the posterior longitudinal ligament (or both) were stated as surgical indications. This study was funded by Providence Medical Technology, Inc. ($32,000). RESULTS: Thirty-three articles were included in the systematic review, and 31 articles were included in the meta-analysis. For all surgical indications and for the 2 subgroup analyses, every cumulative change in patient-reported outcome improved. Many of the reported changes in patient-reported outcome also exceeded the minimal clinically important differences. Pooled outcome rates with all surgical indications were 98.25% for successful fusion, 1.09% for revision, and 9.02% for complications or adverse events. Commonly reported complications or adverse events were axial pain, C5 palsy, transient neurological worsening, and wound infection. CONCLUSIONS: Posterior cervical fusion with decompression resulted in significant clinical improvement, as indicated by the changes in patient-reported outcomes. Additionally, high fusion rates and low rates of revision and of complications and adverse events were found.

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.

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.

Peroneal Nerve Repair of a 9 Year Old: Return of Motor Function after 2 Years.

Major factors that influence functional nerve recovery, postrepair, are length of the nerve defect, type of injury, operative technique, time until treatment, and age of the patient. We present a severe motor nerve defect in a complicated peroneal nerve injury in a 9-year-old that showed functional return after a delayed period of 23 months with sural nerve cable grafting. This case revealed the increased resiliency and regenerative capacity of motor end plates in young patients. In conclusion, autograft for a deep peroneal nerve repair, by means of sural nerve graft, proved to be an acceptable option in children.

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 microl) 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.

Spinal intradural arteriovenous fistulas acquired in late adulthood: absent spinal venous drainage in pathogenesis and pathophysiology. Report of two cases.

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.

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.

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.