Sean J. Nagel

Long-term outcomes of spinal cord stimulation with paddle leads in the treatment of complex regional pain syndrome and failed back surgery syndrome.

Introduction:  Spinal cord stimulation (SCS) is frequently used to treat chronic, intractable back, and leg pain. Implantation can be accomplished with percutaneous leads or paddle leads. Although there is an extensive literature on SCS, the long‐term efficacy, particularly with paddle leads, remains poorly defined. Outcome measure choice is important when defining therapeutic efficacy for chronic pain. Numerical rating scales such as the NRS‐11 remain the most common outcome measure in the literature, although they may not accurately correlate with quality of life improvements and overall satisfaction.

World Health Organization Grades II and III meningiomas are rare in the cranial base and spine.

OBJECTIVEThis study was undertaken to assess a possible relationship between the tumor location and the incidence of World Health Organization (WHO) Grades II and III meningiomas. METHODSA retrospective review of 794 consecutive patients who underwent meningioma resection between January 1991 and March 2004 was conducted. Among these, 47 patients (5.9%) with WHO Grade II meningiomas and 16 patients (2%) with Grade III meningiomas were further analyzed. Tumor location was assessed using preoperative magnetic resonance imaging scans and/or operative reports. Histological grading was done according to the WHO 2000 Classification scheme. RESULTSWHO Grade II tumors were found in eight out of 289 (2.8%) cranial base meningiomas and in zero spinal meningiomas, compared with 39 out of 429 (9.1%) non-cranial base meningiomas. Grade III histology was encountered in two (0.7%) cranial base tumors and in one out of 76 (1.3%) spinal tumors, compared with 13 (3%) non-cranial base tumors. The combined incidence of Grades II and III meningiomas was significantly lower in the cranial base (3.5%) and spinal (1.3%) locations compared with non-cranial base locations (12.1%) (P < 0.001). CONCLUSIONWHO Grades II and III meningiomas occur far less frequently in the cranial base and spinal locations. Tumors arising from these locations may have different mechanisms of tumorigenesis and/or progression compared with meningiomas arising from other (non-cranial base) regions.

Deep Brain Stimulation for Epilepsy

Introduction. There is renewed interest in the use of electrical stimulation to control seizures in patients with medically refractory epilepsy. The evidence indicates that multiple nuclei are involved in the onset, spread, or termination of seizures. Establishing electrical stimulation parameters tailored to these nuclei that best control seizures is ongoing. Methods. The aim of this article is to review the published literature on electrical stimulation of the brain for epilepsy in animals and humans. Results. Animal and human research efforts have focused primarily on the study of the cerebellum, anterior thalamus, centromedian thalamus, substania nigra, caudate nucleus, subthalamic nucleus, and amygdalo‐hippocampal complex. Electrical stimulation of deep brain nuclei has in some instances controlled seizures and epilepsy. The advent of seizure detection devices used in closed‐loop studies has in part redefined the strategy to prevent seizure occurrence and limit spread. Discussion. A number of studies in animals and humans indicate that electrical stimulation may be an alternative treatment for some patients with medically intractable epilepsy who are not candidates for conventional surgical options. Conclusion. The reduction in the number and/or severity of seizures found in some studies supports further investigation into the effects of electrical stimulation on the brain and the continuation of testing in animals and humans.

Preserving cortico-striatal function: deep brain stimulation in Huntington's disease

Huntington’s disease (HD) is an incurable neurodegenerative disease characterized by the triad of chorea, cognitive dysfunction and psychiatric disturbances. Since the discovery of the HD gene, the pathogenesis has been outlined, but to date a cure has not been found. Disease modifying therapies are needed desperately to improve function, alleviate suffering, and provide hope for symptomatic patients. Deep brain stimulation (DBS), a proven therapy for managing the symptoms of some neurodegenerative movement disorders, including Parkinson’s disease, has been reported as a palliative treatment in select cases of HD with debilitating chorea with variable success. New insights into the mechanism of action of DBS suggest it may have the potential to circumvent other manifestations of HD including cognitive deterioration. Furthermore, because DBS is already widely used, reversible, and has a risk profile that is relatively low, new studies can be initiated. In this article we contend that new clinical trials be considered to test the effects of DBS for HD.

Long-term outcomes after replacement of percutaneous leads with paddle leads in a retrospective cohort of patients with spinal cord stimulation systems.

BACKGROUND Although the long-term outcomes for spinal cord stimulation (SCS) have been reported, long-term outcomes of patients who underwent revisions of the SCS with paddle leads are lacking. OBJECTIVE To report the long-term outcomes of 39 patients who had percutaneous SCS revised with a new paddle lead. METHODS Baseline and follow-up mail-in questionnaires assessed pain and disability levels with numerical rating scales, somatotopical overlap between SCS-related paresthesias and areas of chronic pain, and overall satisfaction. Analysis was performed with regard to age, sex, diagnosis, duration of disease, number of surgical revisions, complications, and interval between surgeries. RESULTS After surgical revision, 20 patients (50%) had at least a 3-point reduction in the numerical rating scale. Greater pain reduction was correlated with better coverage (P = .001). Coverage area was greater in patients with a single revision than in patients with multiple revisions (P = .01). Good satisfaction was reported by 25 patients (62.5%) who indicated that they would undergo the procedure again in order to achieve the same results. These patients had significantly greater pain reduction (P = .001) and better coverage (P = .002) than patients who reported otherwise. No other major complication occurred. CONCLUSION Revision of percutaneous SCS systems with implantation of a new paddle lead is safe and more effective in patients who have undergone not more than 1 prior revision.

Spinal Carcinoid Metastasis with Dural Invasion

OBJECTIVE To present the unusual finding of a lumbar intradural carcinoid metastasis in a 67-year-old man with a primary thymic carcinoid diagnosed 16 years before presentation. METHODS The history and imaging findings of this patient are presented, and the literature is reviewed. RESULTS Only three patients with intradural carcinoid tumors, including the one described here, have been reported. In each case, the tumor was discovered in the lumbar region. All patients were treated with surgery. The clinical behavior of metastatic carcinoid in the central nervous system (CNS) and the treatment rationale are also described. CONCLUSIONS Carcinoid tumor metastases are rarely identified in the CNS even in patients with advanced metastatic disease.

Percutaneous Spinal Cord Stimulation for Chronic Pain: Indications and Patient Selection

Percutaneous spinal cord stimulation has a clinical benefit in selected patients with chronic neuropathic pain related to failed back surgery syndrome and complex regional pain syndrome. Patients with other peripheral neuropathic pain syndromes may also respond favorably. The cause of the chronic pain must be established to rule out remediable causes. Drug abuse or aberrant drug-related behaviors should be assessed before proceeding. A psychological evaluation identifies patients who may not benefit. Risk factors for infection should be corrected where possible. This safe, reversible treatment should be considered early for patients with intractable peripheral neuropathic pain.

Spinal Cord Stimulation for Spasticity: Historical Approaches, Current Status, and Future Directions

Millions of people worldwide suffer with spasticity related to irreversible damage to the brain or spinal cord. Typical antecedent events include stroke, traumatic brain injury, and spinal cord injury, although insidious onset is also common. Regardless of the cause, the resulting spasticity leads to years of disability and reduced quality of life. Many treatments are available to manage spasticity; yet each is fraught with drawbacks including incomplete response, high cost, limited duration, dose‐limiting side effects, and periodic maintenance. Spinal cord stimulation (SCS), a once promising therapy for spasticity, has largely been relegated to permanent experimental status.

Impact of 2-staged stereotactic radiosurgery for treatment of brain metastases ≥ 2 cm

OBJECTIVE Stereotactic radiosurgery (SRS) is the primary modality for treating brain metastases. However, effective radiosurgical control of brain metastases ≥ 2 cm in maximum diameter remains challenging and is associated with suboptimal local control (LC) rates of 37%-62% and an increased risk of treatment-related toxicity. To enhance LC while limiting adverse effects (AEs) of radiation in these patients, a dose-dense treatment regimen using 2-staged SRS (2-SSRS) was used. The objective of this study was to evaluate the efficacy and toxicity of this treatment strategy. METHODS Fifty-four patients (with 63 brain metastases ≥ 2 cm) treated with 2-SSRS were evaluated as part of an institutional review board-approved retrospective review. Volumetric measurements at first-stage stereotactic radiosurgery (first SSRS) and second-stage SRS (second SSRS) treatments and on follow-up imaging studies were determined. In addition to patient demographic data and tumor characteristics, the study evaluated 3 primary outcomes: 1) response at first follow-up MRI, 2) time to local progression (TTP), and 3) overall survival (OS) with 2-SSRS. Response was analyzed using methods for binary data, TTP was analyzed using competing-risks methods to account for patients who died without disease progression, and OS was analyzed using conventional time-to-event methods. When needed, analyses accounted for multiple lesions in the same patient. RESULTS Among 54 patients, 46 (85%) had 1 brain metastasis treated with 2-SSRS, 7 patients (13%) had 2 brain metastases concurrently treated with 2-SSRS, and 1 patient underwent 2-SSRS for 3 concurrent brain metastases ≥ 2 cm. The median age was 63 years (range 23-83 years), 23 patients (43%) had non-small cell lung cancer, and 14 patients (26%) had radioresistant tumors (renal or melanoma). The median doses at first and second SSRS were 15 Gy (range 12-18 Gy) and 15 Gy (range 12-15 Gy), respectively. The median duration between stages was 34 days, and median tumor volumes at the first and second SSRS were 10.5 cm3 (range 2.4-31.3 cm3) and 7.0 cm3 (range 1.0-29.7 cm3). Three-month follow-up imaging results were available for 43 lesions; the median volume was 4.0 cm3 (range 0.1-23.1 cm3). The median change in volume compared with baseline was a decrease of 54.9% (range -98.2% to 66.1%; p < 0.001). Overall, 9 lesions (14.3%) demonstrated local progression, with a median of 5.2 months (range 1.3-7.4 months), and 7 (11.1%) demonstrated AEs (6.4% Grade 1 and 2 toxicity; 4.8% Grade 3). The estimated cumulative incidence of local progression at 6 months was 12% ± 4%, corresponding to an LC rate of 88%. Shorter TTP was associated with greater tumor volume at baseline (p = 0.01) and smaller absolute (p = 0.006) and relative (p = 0.05) decreases in tumor volume from baseline to second SSRS. Estimated OS rates at 6 and 12 months were 65% ± 7% and 49% ± 8%, respectively. CONCLUSIONS 2-SSRS is an effective treatment modality that resulted in significant reduction of brain metastases ≥ 2 cm, with excellent 3-month (95%) and 6-month (88%) LC rates and an overall AE rate of 11%. Prospective studies with larger cohorts and longer follow-up are necessary to assess the durability and toxicities of 2-SSRS.

Intrathecal Therapeutics: Device Design, Access Methods, and Complication Mitigation

The intrathecal space remains underutilized for diagnostic testing, invasive monitoring or as a pipeline for the delivery of neurological therapeutic agents and devices. The latter including drug infusions, implants for electrical modulation, and a means for maintaining the physiologic pressure column. The reasons for this are many but include unfamiliarity with the central nervous system and the historical risks that continue to overshadow the low complication rates in modern clinical series.