High Frequency Spinal Cord Stimulation for Complex Regional Pain Syndrome: A Case Report.

Complex regional pain syndrome (CRPS) is a chronic, debilitating, neuropathic pain condition which is often misdiagnosed, difficult to manage, and lacks proven methods for remission. Most available methods provide some relief to a small percentage of patients. Recent FDA approval and superiority of the Nevro Senza 10-kHz high frequency (HF10) spinal cord stimulation (SCS) therapy over traditional low-frequency spinal cord stimulation for treatment of chronic back and leg pain may provide a new interventional therapeutic option for patients suffering from CRPS. We provide a case report of a 53-year-old Caucasian woman who suffered with CRPS in the right knee and thigh for over 7 years. Implantation of the HF10 device provided over 75% relief of pain, erythema, heat, swelling, and tissue necrosis to the entire region within 1 month of treatment. Because the HP10 therapy provides pain relief without paresthesia typical of traditional low-frequency, this system may provide relief for patients suffering from chronic pain.Key words: Complex regional pain syndrome, spinal cord stimulation, Nevro Senza HF10, erythema, knee, thigh.

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.

Air embolus to arachnoid cyst as a rare delayed complication of intrathecal medication delivery.

INTRODUCTION: Intrathecal (IT) medication delivery is a commonly used technique for the treatment of chronic intractable pain. Cerebrospinal fluid (CSF) loculation at the catheter tip has been described as a cause of progressive loss of drug effect that can often be difficult to diagnose. METHODS: The clinical course of a 56-year-old woman was reviewed, including past imaging studies. RESULTS: The patient presented with acute lower extremity paresis secondary to air trapped within an arachnoid cyst thought to be due to long-term use of IT morphine and an undiagnosed CSF loculation. She rapidly recovered after surgical decompression. DISCUSSION: Symptomatic pneumorachis is rare. In this case, because of radiographically impressive compression and severe deficit, we felt that the trapped air was equivalent to a mass lesion and treated it aggressively. The arachnoid cyst was near the level of the catheter tip prior to revision, and we have retrospectively inferred a causal relationship.

Percutaneous cephalocaudal implantation of epidural stimulation electrodes over sacral nerve roots--a technical note on the importance of the lateral approach.

OBJECTIVE: Idiopathic overactive bladder, urgency-frequency syndromes, interstitial cystitis, pudendal neuralgia, vulvodynia, prostadynia, and coccygodynia have been effectively treated with sacral nerve root modulation. This is most commonly performed with placement of electrodes via a transforaminal approach, predominately to the S3 foramen. This approach is limited by a high lead migration rate and the limitations of stimulating a single nerve root. Beginning in the 1990s, some centers began pursuing retrograde percutaneous placement from the lumbar spine, but adoption of this technique was limited by the technical difficulty of the approach. METHODS AND MATERIALS: We developed a lateral approach to the epidural space for these procedures, which has improved the learning curve and facilitated the application of the retrograde technique. In this technical note, we describe the "laterograde" approach. RESULTS: A focused description of the technique is presented in this technical report. The epidural space is accessed from lateral to medial with the bevel facing up to keep the approach to the "shingled" lumbar laminae shallow. CONCLUSION: The "laterograde" modification of cephalocaudal approach appears to be technically less difficult method for accomplishing sacral nerve root stimulator electrode placement over multiple roots.

Feasibility of anterior cervical discectomy and fusion as an outpatient procedure.

BACKGROUND: Anterior cervical discectomy and fusion (ACDF) procedures are increasingly being managed on an outpatient basis. Currently there are no definitive guidelines within the literature that delineate which patient population can safely be managed as such. The purpose of this study is to demonstrate that ACDF procedures, within a selective patient population at our institution, can be safely performed on an outpatient basis. METHODS: This is a retrospective chart review within one physician's practice of patients undergoing instrumented ACDF procedures using allograft. This sample included 117 patients who underwent one- and two-level ACDF procedures from November 2005 to April 2009. Hospital length of stay and hospital readmissions were noted. Complication rates in the outpatient population were assessed to determine the feasibility of outpatient management for selective patients undergoing ACDF procedures. RESULTS: A total of 59 patients (50%) were treated on an outpatient basis. Sixty-eight patients underwent single level ACDF procedures, 38 patients (56%) of which were discharged on the same day. Forty-nine patients underwent two-level ACDF procedures, 21 patients (43%) of which were discharged on the same day. There was one complication (1.4%) in patients who were discharged on the same day. That patient required readmission for 23-hour observation secondary to neck swelling. CONCLUSIONS: ACDF procedures involving single and two-level fusions can safely be performed on an outpatient basis. Complication rates associated with this procedure are low, with critical postoperative complications involving respiratory compromise occurring very infrequently and in the immediate postoperative period.

Percutaneous peripheral nerve stimulation.

Since its inception in the 1970s, peripheral neuromodulation has become an increasingly common procedure to treat chronic neuropathic disorders. Historically, peripheral nerve stimulation (PNS) originated with the placement of large surface cuff electrodes, which was refined by the introduction of functional nerve mapping with circumferential electrical stimulation. This substantially improved the targeting of sensory fascicles. Surgical placement of spinal cord stimulation (SCS) 'button type' paddle electrodes was replaced when the introduction of percutaneous cylindrical SCS electrodes expanded the spectrum of PNS applications and improved the ability to target afferent sensory fibers as well as reducing the complication rate. To further refine functional mapping for the placement of these percutaneous electrodes, radiofrequency needle probes have more recently been employed to elicit paresthesias in awake patients to map the pain generators and guide treatment. In this chapter, we provide a description of the development and basic mechanisms of peripheral nerve stimulation, as well as a more detailed description of the two most commonly employed forms of peripheral nerve stimulation: occipital nerve stimulation for occipital neuralgia, and subcutaneous peripheral nerve field stimulation to stimulate free nerve endings within the subcutaneous tissue when the pain is limited to a small, well-localized area. The closely related ideas of internal and external targeted subcutaneous stimulation are also discussed.

Anatomic study of the infraorbital foramen for radiofrequency neurotomy of the infraorbital nerve.

OBJECTIVE: To examine the anatomy of the infraorbital canal and foramen and the angles at which a radiofrequency probe must be directed to enter the infraorbital foramen and canal, as a guide to performing radiofrequency ablation of the infraorbital nerve in patients with relative or absolute contraindications to lesions of the trigeminal ganglion or posterior root. METHODS: Eleven cadaveric skulls were studied. The infraorbital nerve, after passing through the infraorbital foramen, enters the infraorbital canal and groove in the floor of the orbit before reaching the foramen rotundum. Small probes were placed through the foramen into the infraorbital canal, and pictures were taken in the anteroposterior and sagittal planes. The pictures were analyzed using the ImageTool program (University of Texas Health Science Center, San Antonio, TX) to calculate the anteroposterior and sagittal angles of the probe. The distances of the foramen from the midline, lateral edge of the anterior nasal aperture, and inferior orbital rim were examined. RESULTS: A probe introduced through the cheek from below and medial to the foramen and directed upward and laterally at an angle of approximately 22 degrees in the coronal plane and 120 degrees in the sagittal plane toward a point approximately 26 mm from the midline and 8 mm below the inferior orbital rim will penetrate the infraorbital foramen for placement of the probe's tip in the infraorbital canal. CONCLUSION: The coordinates for placement of the radiofrequency probe through the infraorbital foramen and into the infraorbital canal are reviewed, along with a discussion of pitfalls in radiofrequency ablation of the nerve.

Cingulotomy for psychiatric disease: microelectrode guidance, a callosal reference system for documenting lesion location, and clinical results.

OBJECTIVE: To evaluate magnetic resonance imaging (MRI)- and microelectrode recording-guided cingulotomy for patients with psychiatric disorders and to develop a new method of mapping lesion location in anterior cingulate cortex that takes into account the significant interindividual variability in callosal morphometry. METHODS: MRI and microelectrode recording were used to guide placement of radiofrequency lesions in patients with obsessive-compulsive disorder (n = 21) or affective disorders (n = 5). Postoperative improvement was evaluated with the Yale-Brown Obsessive-Compulsive Scale in 15 of the 21 obsessive-compulsive disorder patients studied. From the postoperative MRI scans, we developed a coordinate system for position in the anterior cingulate cortex. The callosal line passes from the most anterior point of the corpus callosum (c = 0) to the most posterior (c = 100). We reconstructed the lesions onto a sagittal map from the Talairach and Tournoux atlas using the distance along the callosal line and the distance above the upper surface of the corpus callosum. RESULTS: The location of neuronal activity distinguished gray and white matter and was useful in delineating the upper and lower cortical banks of the cingulate gyrus, the cingulate bundle, and the corpus callosum. This information was used to place the lesions. Lesions typically were 6 to 8 mm in diameter on T2-weighted MRI scans. The inferior margins were along the corpus callosum from c = 16 to c = 38. Four of 15 patients with obsessive-compulsive disorder had a documented decrease of more than 35% on the Yale-Brown Obsessive-Compulsive Scale, but only one patient had a sustained benefit for more than 1 year. CONCLUSION: Microelectrode recording is useful for lesion placement. Our system for reporting location in anterior cingulate cortex normalizes for differences in callosal morphometry. These techniques may aid future study.

Development of syringohydromyelia associated with Dandy-Walker malformation: treatment with cystoperitoneal shunt placement. Case report.

Dandy-Walker malformation (DWM) is a well-described clinical entity, which includes vermian agenesis, posterior fossa cysts, and frequently, hydrocephalus. The authors report the clinical course and present the radiographic findings pertaining to a 1-month-old girl with DWM who was treated initially with a ventriculoperitoneal shunt and endoscopic fenestration of a posterior fossa cyst. After decompression for hydrocephalus, an increased mass effect at the foramen magnum from her posterior fossa cyst was demonstrated, as well as subsequent development of syringohydromyelia from C-4 to T-7. She was treated with a cystoperitoneal shunt. At the 6-month follow-up examination, the child (15 months of age) had achieved gains in developmental milestones, and complete resolution of the syrinx was established through MR imaging. This is the fourth nonautopsy pediatric case of DWM-associated syringohydromyelia reported in the literature and the third in a child to demonstrate impaction of the posterior fossa cyst at the foramen magnum leading to syrinx formation with subsequent treatment and resolution. Spinal imaging may be useful in the evaluation of patients with DWM who do not experience expected improvement after shunt procedures.

Preoperative endovascular brain mapping for intraoperative volumetric image guidance: preliminary concept and feasibility in animal models.

OBJECT: The authors describe a novel concept for brain mapping in which an endovascular approach is used, and they demonstrate its feasibility in animal models. The purpose of endovascular brain mapping is to delineate clearly the nonfunctional brain parenchyma when a craniotomy is performed for resection. The nonfunctional brain will be stained with sharp visual margins, differentiating it from the functional, nonstained brain. The authors list four essential criteria for developing an ideal endovascular mapping agent, and they describe seven potential approaches for accomplishing a successful endovascular brain map. METHODS: Four Sprague-Dawley rats and one New Zealand white rabbit were used to determine initial feasibility of the procedure. The animals were anesthetized, and the internal carotid artery was catheterized. Four potential brain mapping agents were infused into the right hemisphere of the five animals. Afterward, the brains were removed and each was analyzed both grossly and histologically. Fluorescein and FD&C Green No. 3 provided good visual clarity and margins, but required blood-brain barrier (BBB) manipulation. Tantalum particles enabled avoidance of BBB manipulation, but provided inadequate visual clarity, probably because of their size. A Sudan black "cocktail" provided excellent clarity and margins despite remaining in the brain capillaries. CONCLUSIONS: This is a novel application of the endovascular approach, and has broad potential for clinical neurosurgical brain mapping. The animal models in this study establish the feasibility of the procedure. However, further study is required to demonstrate safety, minimize toxicity, investigate stain durability, and improve the characteristics of potential mapping agents. The authors are planning to conduct future studies for identification of mapping agents that do not require BBB manipulation or vascular occlusion.

Brainstem stereotactic biopsy sampling in children.

OBJECT: Although it is widely accepted that biopsy sampling is not indicated for the diagnosis and empiric treatment of diffuse pontine glioma, it is common to encounter patients with brainstem lesions that cannot be diagnosed on the basis of imaging studies alone. In cases not amenable to resection, a tissue diagnosis may still be necessary to make appropriate treatment recommendations. The authors retrospectively reviewed their institutional experience with stereotactic biopsy procedures in pediatric patients during a 4-year period. METHODS: A three-dimensional graphics workstation was used for trajectory planning to obtain biopsy samples of brainstem lesions in 10 patients. One patient experienced mild diplopia postoperatively. No other morbidity was noted; no patient died as a result of the procedure. The biopsy procedure yielded a pathological diagnosis in all cases. A later resection in one patient resulted in a change in diagnosis. Overall, the pathological findings were varied, and in some cases the tissue diagnosis altered the treatment recommendations. CONCLUSIONS: The findings in this small series suggest that brainstem stereotactic biopsy sampling in children is a safe procedure with a high diagnostic yield. In patients in whom radiographic findings are not consistent with diffuse pontine glioma and resection is not appropriate, stereotactic biopsy sampling should be considered.

Human anterior cingulate cortex neurons encode cognitive and emotional demands.

The cortical mechanisms and substrates of cognitive and emotional demands are poorly understood. Lesion studies and functional imaging implicate the anterior cingulate cortex (ACC). The caudal ACC (cACC) has been implicated in cognitive processes such as attention, salience, interference, and response competition, mostly on the basis of neuroimaging results. To test the hypothesis that individual cACC neurons subserve these functions, we monitored neuronal activity from single cells in the cACC while subjects were engaged in a mental arithmetic task, the cognitively demanding counting Stroop task, and/or the emotional Stroop interference task. We now report the first direct measures of single neurons in humans identifying a population of cACC neurons that respond differentially or in a graded manner to cognitively demanding high- and low-conflict Stroop tasks, including those with emotional valence. These data indicate that cACC neurons may be acting as salience detectors when faced with conflict and difficult or emotional stimuli, consistent with neuroimaging results of cACC responses to abrupt sensory, novel, task-relevant, or painful stimuli.

Correspondence of microelectrode mapping with magnetic resonance imaging for subthalamic nucleus procedures.

BACKGROUND: Magnetic resonance imaging (MRI) and microelectrode recording (MER) are commonly used to guide stereotactic procedures on the subthalamic nucleus (STN). Little is known about the correlation between the position of the STN as seen on MRI and that as determined by MER mapping. We compared these in 10 patients with Parkinson's disease. METHODS: The position of the STN was determined by intraoperative MER findings and stereotactic axial T2 magnetic resonance images with 2-mm slice thickness. Images were reconstructed in a 3-dimensional workstation. The anterior, posterior, medial, lateral, dorsal, and ventral borders of the STN defined with the MRI were measured relative to the midcommissural point. The location of STN activity during MER was reconstructed relative to the midcommissural point for comparison. RESULTS: Twenty-nine tracks recorded with microelectrodes provided clear spans of STN-like activity in 18 STN nuclei. The coordinates of MER were, in general, within the borders of the STN defined with the MRI. However, when analyzed individually, some of the tracks had STN-like activity outside the borders of the MRI-defined nucleus (mostly <1 mm). Three tracks had STN-like activity recorded between 2 and 3 mm more anterior than the anterior border of the nucleus defined with the MRI. CONCLUSIONS: There was a good correlation between MER and the borders of the STN defined in the MRI, except for the anterior-posterior axis, in which MER indicated that the STN extended more anteriorly than as suggested by MRI. This should be taken into account in STN surgery.

Cingulotomy for psychiatric disease: microelectrode guidance, a callosal reference system for documenting lesion location, and clinical results.

OBJECTIVE: To evaluate magnetic resonance imaging (MRI)- and microelectrode recording-guided cingulotomy for patients with psychiatric disorders and to develop a new method of mapping lesion location in anterior cingulate cortex that takes into account the significant interindividual variability in callosal morphometry. METHODS: MRI and microelectrode recording were used to guide placement of radiofrequency lesions in patients with obsessive-compulsive disorder (n = 21) or affective disorders (n = 5). Postoperative improvement was evaluated with the Yale-Brown Obsessive-Compulsive Scale in 15 of the 21 obsessive-compulsive disorder patients studied. From the postoperative MRI scans, we developed a coordinate system for position in the anterior cingulate cortex. The callosal line passes from the most anterior point of the corpus callosum (c = 0) to the most posterior (c = 100). We reconstructed the lesions onto a sagittal map from the Talairach and Tournoux atlas using the distance along the callosal line and the distance above the upper surface of the corpus callosum. RESULTS: The location of neuronal activity distinguished gray and white matter and was useful in delineating the upper and lower cortical banks of the cingulate gyrus, the cingulate bundle, and the corpus callosum. This information was used to place the lesions. Lesions typically were 6 to 8 mm in diameter on T2-weighted MRI scans. The inferior margins were along the corpus callosum from c = 16 to c = 38. Four of 15 patients with obsessive-compulsive disorder had a documented decrease of more than 35% on the Yale-Brown Obsessive-Compulsive Scale, but only one patient had a sustained benefit for more than 1 year. CONCLUSION: Microelectrode recording is useful for lesion placement. Our system for reporting location in anterior cingulate cortex normalizes for differences in callosal morphometry. These techniques may aid future study.

Determining the position and size of the subthalamic nucleus based on magnetic resonance imaging results in patients with advanced Parkinson disease.

OBJECT: The subthalamic nucleus (STN) is a target in surgery for Parkinson disease, but its location according to brain atlases compared with its position on an individual patient's magnetic resonance (MR) images is incompletely understood. In this study both the size and location of the STN based on MR images were compared with those on the Talairach and Tournoux, and Schaltenbrand and Wahren atlases. METHODS: The position of the STN relative to the midcommissural point was evaluated on 18 T2-weighted MR images (2-mm slices). Of 35 evaluable STNs, the most anterior, posterior, medial, and lateral borders were determined from axial images, dorsal and ventral borders from coronal images. These methods were validated using histological measurements in one case in which a postmortem examination was performed. The mean length of the anterior commissure-posterior commissure was 25.8 mm. Subthalamic nucleus borders derived from MR imaging were highly variable: anterior, 4.1 to -3.7 mm relative to the midcommissural point; posterior, 4.2 to 10 mm behind the midcommissural point; medial, 7.9 to 12.1 mm from the midline; lateral, 12.3 to 15.4 mm from the midline; dorsal, 0.2 to 4.2 mm below the intercommissural plane; and ventral, 5.7 to 9.9 mm below the intercommissural plane. The position of the anterior border on MR images was more posterior, and the medial border more lateral, than its position in the brain atlases. The STN was smaller on MR images compared with its size in atlases in the anteroposterior (mean 5.9 mm), mediolateral (3.7 mm), and dorsoventral (5 mm) dimensions. CONCLUSIONS: The size and position of the STN are highly variable, appearing to be smaller and situated more posterior and lateral on MR images than in atlases. Care must be taken in relying on coordinates relative to the commissures for targeting of the STN.