Treatment of contact dermatitis associated with spinal cord stimulator pulse generator--technical note

BACKGROUND

Expanded polytetrafluoroethylene sheets have been successfully used as a biologic barrier in the treatment of pacemaker contact dermatitis.

TECHNIQUE

In this report, we describe two patients with contact dermatitis related to the implantable pulse generator of a spinal cord stimulator who were treated with expanded polytetrafluoroethylene as a barrier.

RESULTS

Resolution of the dermatitis was achieved in both cases.

CONCLUSIONS

This technique is an effective way of treating contact dermatitis related to implantable pulse generators, without the need for explantation of the neuromodulation system.

Deep brain stimulation entrains local neuronal firing in human globus pallidus internus

Deep brain stimulation (DBS) in the internal segment of the globus pallidus (GPi) relieves the motor symptoms of Parkinson's disease, yet the mechanism of action remains uncertain. To address the question of how therapeutic stimulation changes neuronal firing in the human brain, we studied the effects of GPi stimulation on local neurons in unanesthetized patients. Eleven patients with idiopathic Parkinson's disease consented to participate in neuronal recordings during stimulator implantation surgery. A recording microelectrode and a DBS macroelectrode were advanced through the GPi in parallel until a single neuron was isolated. After a baseline period, stimulation was initiated with varying voltages and different stimulation sites. The intra-operative stimulation parameters (1-8 V, 88-180 Hz, 0.1-ms pulses) were comparable with the postoperative DBS settings. Stimulation in the GPi did not silence local neuronal activity uniformly, but instead loosely entrained firing and decreased net activity in a voltage-dependent fashion. Most neurons had decreased activity during stimulation, although some increased or did not change firing rate. Thirty-three of 45 neurons displayed complex patterns of entrainment during stimulation, and burst-firing was decreased consistently after stimulation. Recorded spike trains from patients were used as input into a model of a thalamocortical relay neuron. Only spike trains that occurred during therapeutically relevant voltages significantly reduced transmission error, an effect attributable to changes in firing patterns. These data indicate that DBS in the human GPi does not silence neuronal activity, but instead disrupts the pathological firing patterns through loose entrainment of neuronal activity.

DREZotomy in the treatment of cancer pain: a review

BACKGROUND

Cancer-related pain is a common problem that may be intractable by medical and neuromodulatory treatment. The dorsal root entry zone (DREZ) is a hyperactive focus in neuropathic pain syndromes, and DREZotomy has been used in selective cases of neuropathic cancer pain.

OBJECTIVE

The aim of this study was to describe the technique of spinal DREZotomy in the treatment of cancer pain and review the relevant published literature.

METHODS

A PubMed database search for 'DREZ', 'dorsal root entry zone' and 'cancer', and a search of the references of these manuscripts, was undertaken.

RESULTS

14 papers were identified and reviewed that described a total of 123 patients with cancer pain or radiation-induced pain who have been treated with DREZotomy. Though heterogeneous, these studies reported an overall favorable outcome in carefully selected patients with topographically limited pain syndromes.

CONCLUSION

For patients with well-localized neuropathic cancer pain intractable to medical and first-line surgical management, DREZotomy is a viable treatment option. Further prospective studies are needed to evaluate the outcomes of this procedure.

Deep brain stimulation for Tourette syndrome: target selection

BACKGROUND/AIMS

Tourette syndrome (TS) is a complex neurological disorder manifested chiefly by motor and phonic tics and a variety of behavioral comorbidities, including attention disorder, obsessive-compulsive disorder and impulse control problems. Surgical treatment is increasingly considered when tics become troublesome or even disabling or self-injurious despite optimal medical therapy. In this review, we describe the surgical techniques, stimulation parameters, outcomes of deep brain stimulation (DBS) in TS, and critically review target choices.

METHODS

A search of the PubMed database was performed to identify all articles discussing DBS and TS. 'Tourette' and 'Stimulation' were used as MeSH headings.

RESULTS

Since the first report of thalamic DBS for TS in 1999, follow-up on less than 100 patients has been reported in the literature. Reported targets for DBS include the thalamic centromedian nucleus and substantia periventricularis, posteroventral globus pallidus internus, ventromedial globus pallidus internus, globus pallidus externus, anterior limb of the internal capsule and nucleus accumbens.

CONCLUSIONS

Determination of the optimal surgical target will require a multicenter, randomized trial, and an expanded understanding of the neurobiology of TS.

Warfarin-related intraventricular hemorrhage: imaging and outcome

OBJECTIVE

Oral anticoagulation therapy (OAT) with warfarin increases mortality and disability after intracerebral hemorrhage (ICH), the result of increased ICH volume and risk of hematoma expansion. We investigated whether OAT also influences risk of development of intraventricular hemorrhage (IVH), the volume of IVH and IVH expansion, and whether IVH is a substantive mediator of the overall effect of OAT on ICH outcome.

METHODS

We performed a retrospective analysis of a prospectively collected single-center cohort of 1,879 consecutive ICH cases (796 lobar, 865 deep, 153 cerebellar, 15 multiple location, 50 primary IVH) from 1999 to 2009. ICH and IVH volumes at presentation, as well as hematoma expansion (>33% or >6 mL increase) and IVH expansion (>2 mL increase), were determined using established semiautomated methods. Outcome was assessed at 90 days using either the modified Rankin Scale or Glasgow Outcome Scale.

RESULTS

Warfarin use was associated with IVH risk, IVH volume at presentation, and IVH expansion in both lobar and deep ICH (all p < 0.05) in a dose-response relationship with international normalized ratio. Warfarin was associated with poor outcome in both lobar and deep ICH (p < 0.01), and >95% of this effect was accounted for by baseline ICH and IVH volumes, as well as ICH and IVH expansion.

CONCLUSION

Warfarin increases IVH volume and risk of IVH expansion in lobar and deep ICH. These findings (along with effects on ICH volume and expansion) likely represent the mechanisms by which anticoagulation worsens ICH functional outcome.

Correlations between MRI white matter lesion location and executive function and episodic memory

OBJECTIVES

MRI white matter hyperintensity (WMH) volume is associated with cognitive impairment. We hypothesized that specific loci of WMH would correlate with cognition even after accounting for total WMH volume.

METHODS

Subjects were identified from a prospective community-based study: 40 had normal cognition, 94 had mild impairment (defined here as a Clinical Dementia Rating [CDR] score of 0.5 without dementia), and 11 had mild Alzheimer's dementia. Factor analysis of a 22-item neuropsychological battery yielded 4 factors (episodic memory, executive function, spatial skills, and general knowledge). MRI WMH segmentation and analysis was performed using FreeSurfer software.

RESULTS

Higher WMH volume was independently associated with lower executive function and episodic memory factor scores. Voxel-based general linear models showed loci where WMH was strongly inversely associated with specific cognitive factor scores (p < 0.001), controlling for age, education, sex, APOE genotype, and total WMH volume. For episodic memory, clusters were observed in bilateral temporal-occipital and right parietal periventricular white matter, and the left anterior limb of the internal capsule. For executive function, clusters were observed in bilateral inferior frontal white matter, bilateral temporal-occipital and right parietal periventricular white matter, and the anterior limb of the internal capsule bilaterally.

CONCLUSIONS

Specific WMH loci are closely associated with executive function and episodic memory, independent of total WMH volume. The anatomic locations suggest that WMH may cause cognitive impairment by affecting connections between cortex and subcortical structures, including the thalamus and striatum, or connections between the occipital lobe and frontal or parietal lobes.

Initial experience with the use of an expandable titanium cage as a vertebral body replacement in patients with tumors of the spinal column: a report of 95 patients

OBJECTIVE

Vertebral body resection to treat spine tumors necessitates reconstruction to maintain spinal stability. The durability of reconstruction may be a challenge in cancer patients as treatment with chemotherapy and/or radiation coupled with poor nutritional status may compromise bone quality. We present a series of patients who underwent implantation of an expandable titanium cage (ETC) for reconstruction after vertebral body resection for primary or metastatic spine tumors. We report the functional outcome, assess the durability of reconstruction, and describe complications associated with this procedure.

METHODS

A retrospective review of patients undergoing placement of ETC after vertebrectomy for spinal tumor at our institution was performed.

RESULTS

From September 2001 to August 2006, 95 patients underwent implantation of an ETC for reconstruction of the anterior spinal column following vertebrectomy for tumor (75 one-level, 19 two-level, 1 three-level). All patients underwent spinal stabilization as well. The median survival after surgery was 13.7 months; 23 patients had primary spinal tumors and 72 had metastatic tumors. Numerical pain scores were significantly improved postoperatively indicating a palliative benefit. No new neurological deficits were noted postoperatively, except when intentional neurological sacrifice was performed for oncologic reasons. Median height correction of 14% (range 0-118%) and median improvement in sagittal alignment of 6° (range 0-28°) were demonstrated on immediate postoperative imaging. Three patients experienced hardware related complications, one of which had posterior migration of the ETC. On postoperative imaging, 12 patients demonstrated subsidence of greater than 1 mm, but none required operative revision.

CONCLUSION

Use of an ETC for spinal reconstruction in patients with spinal tumors is safe, decreases pain associated with pathologic fracture, protects neurologic function, and is durable. We found a very low incidence of cage-related construct failures and no significant problems with subsidence.

Extraventricular corpus callosotomy

Corpus callosotomy offers useful palliation for selected patients with medically intractable seizures, particularly those with uncontrolled and disabling drop attacks. Here the authors present their technique for performing a corpus callosotomy that allows for complete sectioning of the callosum while avoiding entry into the lateral ventricles. The anatomical basis for the technique is the presence of a definable cleft just ventral to the corpus callosum in the midline, formed by the fusion of the two laminae of the septum pellucidum. This small cleft is typically present even in the absence of a cavum septum pellucidum on MR imaging. The authors have found that dividing the body of the corpus callosum by exploiting the cleft of the septum pellucidum in the absolute midline is a simple and expeditious way to perform a callosotomy without entering the lateral ventricles.

Statin use and outcome after intracerebral hemorrhage: case-control study and meta-analysis

OBJECTIVES

Intracerebral hemorrhage (ICH) is a highly lethal disease of the elderly. Use of statins is increasingly widespread among the elderly, and therefore common in patients who develop ICH. Accumulating data suggests that statins have neuroprotective effects, but their association with ICH outcome has been inconsistent. We therefore performed a meta-analysis of all available evidence, including unpublished data from our own institution, to determine whether statin exposure is protective for patients who develop ICH.

METHODS

In our prospectively ascertained cohort, we compared 90-day functional outcome in 238 pre-ICH statin cases and 461 statin-free ICH cases. We then meta-analyzed results from our cohort along with previously published studies using a random effects model, for a total of 698 ICH statin cases and 1,823 non-statin-exposed subjects.

RESULTS

Data from our center demonstrated an association between statin use before ICH and increased probability of favorable outcome (odds ratio [OR] = 2.08, 95% confidence interval [CI] 1.37-3.17) and reduced mortality (OR = 0.47, 95% CI 0.32-0.70) at 90 days. No compound-specific statin effect was identified. Meta-analysis of all published evidence confirmed the effect of statin use on good outcome (OR = 1.91, 95% CI 1.38-2.65) and mortality (OR = 0.55, 95% CI 0.42-0.72) after ICH.

CONCLUSION

Antecedent use of statins prior to ICH is associated with favorable outcome and reduced mortality after ICH. This phenomenon appears to be a class effect of statins. Further studies are required to clarify the biological mechanisms underlying these observations.

Aspirin and recurrent intracerebral hemorrhage in cerebral amyloid angiopathy

OBJECTIVE

To identify and compare clinical and neuroimaging predictors of primary lobar intracerebral hemorrhage (ICH) recurrence, assessing their relative contributions to recurrent ICH.

METHODS

Subjects were consecutive survivors of primary ICH drawn from a single-center prospective cohort study. Baseline clinical, imaging, and laboratory data were collected. Survivors were followed prospectively for recurrent ICH and intercurrent aspirin and warfarin use, including duration of exposure. Cox proportional hazards models were used to identify predictors of recurrence stratified by ICH location, with aspirin and warfarin exposures as time-dependent variables adjusting for potential confounders.

RESULTS

A total of 104 primary lobar ICH survivors were enrolled. Recurrence of lobar ICH was associated with previous ICH before index event (hazard ratio [HR] 7.7, 95% confidence interval [CI] 1.4-15.7), number of lobar microbleeds (HR 2.93 with 2-4 microbleeds present, 95% CI 1.3-4.0; HR = 4.12 when >or=5 microbleeds present, 95% CI 1.6-9.3), and presence of CT-defined white matter hypodensity in the posterior region (HR 4.11, 95% CI 1.01-12.2). Although aspirin after ICH was not associated with lobar ICH recurrence in univariate analyses, in multivariate analyses adjusting for baseline clinical predictors, it independently increased the risk of ICH recurrence (HR 3.95, 95% CI 1.6-8.3, p = 0.021).

CONCLUSIONS

Recurrence of lobar ICH is associated with previous microbleeds or macrobleeds and posterior CT white matter hypodensity, which may be markers of severity for underlying cerebral amyloid angiopathy. Use of an antiplatelet agent following lobar ICH may also increase recurrence risk.

Commissural myelotomy in the treatment of intractable visceral pain: technique and outcomes

BACKGROUND

Commissural myelotomy can be valuable for patients with intractable pain associated with malignancy in the abdominal or pelvic region.

METHODS

Between December 1992 and June 2009, 11 patients underwent commissural myelotomy at the University of Texas MD Anderson Cancer Center for the treatment of intractable lower extremity, thoracic, pelvic or sacral pain associated with unresectable tumors. The various surgical approaches to myelotomy are discussed.

RESULTS

Eight patients had excellent or good outcomes with regard to pain relief, defined as no further pain (excellent) or a significant reduction in pain and not requiring opioids stronger than codeine (good). Complications included new leg weakness (n = 3) and bladder dysfunction (n = 1).

CONCLUSION

We found that for the properly selected patient, open midline commissural myelotomy can provide effective pain relief with acceptable postoperative morbidity.

Hybrid Spinal Constructs Using Sublaminar Polyester Bands in Posterior Instrumented Fusions in Children

OBJECTIVE

The authors report the novel use of sublaminar polyester bands in posterior instrumented spinal fusions of the thoracic and lumbar spine and sacrum in 5 children. This is the first reported use of polyester bands in spinal surgery in the United States.

METHODS

The authors retrospectively reviewed the demographics and procedural data for children who underwent posterior instrumented fusion using sublaminar polyester bands.

RESULTS

Five children, ranging in age from 9 months to 18 years, underwent posterior instrumented fusion for posttrauma kyphotic deformity (1 patient), congenital scoliosis from hemivertebra anomaly (3 patients), and neuromuscular scoliosis associated with spina bifida (1 patient). There were 1 instance of lamina fracture with application and tensioning of the polyester band and 1 instance of transient worsening of proprioception with sublaminar passage of the polyester band.

CONCLUSION

Pedicle screws, laminar/pedicle/transverse process hooks, and sublaminar metal wires have been incorporated into posterior spinal constructs and widely reported and used in the thoracic and lumbar spine and sacrum with varying success. This report demonstrates the successful results of hybrid posterior spinal constructs that include sublaminar polyester bands that promise the technical ease of passing sublaminar instrumentation with the immediate biomechanical rigidity of pedicle screws and hooks.

Surgical management of the pelvic plexus and lower abdominal nerves

OBJECTIVE

Nerves of the pelvic plexus and lower abdominal wall can lead to chronic neuralgias owing to a variety of causes, including iatrogenic injury, trauma, tumors, and primary nerve entrapment. Differentiating among the various neural etiologies can be a challenging task. Here, we present a large series of patients who underwent surgical treatment of these nerves, with an emphasis on diagnostic and therapeutic considerations.

METHODS

Between 1970 and 2006, the senior authors (DGK and DHK) surgically treated 264 cases of neuralgia of the pelvic plexus and nerves. A retrospective analysis of the patients' history, physical, diagnostic examinations, and follow-up was performed.

RESULTS

Twenty-five cases of solely ilioinguinal neuralgia and 24 cases of combined ilioinguinal neuralgias were treated. Of these, iatrogenic injury was the most common etiology. One hundred forty-five patients underwent surgical exploration for either femoral nerve injury (119 patients) or lateral femoral cutaneous compression (26 patients). Seventy-five percent of patients had femoral nerve injuries attributable to trauma (iatrogenic versus penetrating injuries), and the remaining 25% of patients had cystic masses or tumors. Fifty-two masses of the pelvic plexus were treated, including neurofibromas (68%), schwannomas (18%), malignant nerve sheath tumors (5%), and non-neural sheath tumors (9%).

CONCLUSION

Effective surgical management of these complex neuralgias depends on a solid understanding of the surgical anatomy and proper diagnosis. Electromyography and local anesthetic blocks not only can provide insight into the diagnosis but also have predictive value in assessing which patients may benefit from neurectomy or neurolysis.

Unsuspected coagulopathy rarely prevents IV thrombolysis in acute ischemic stroke

BACKGROUND

American Heart Association/American Stroke Association guidelines recommend initiating treatment with IV tissue plasminogen activator (tPA) in acute ischemic stroke patients without suspected coagulopathy prior to availability of clotting results; however, little or no data support this practice. We sought to identify how often blood clotting abnormalities were responsible for withholding IV tPA at our institution.

METHODS

We conducted a retrospective review of our prospectively acquired Get With the Guidelines Stroke database from January 2003 to April 2008. All patients underwent clinical evaluation by a neurologist, diagnostic neuroimaging, and laboratory testing on admission. We classified patients with absolute contraindications to IV tPA as ineligible, and those with warnings/relative contraindications or potentially treatable factors as potentially eligible.

RESULTS

Of 2,335 considered for analysis, 470 (20.1%) patients presented to our emergency department (ED) within 3 hours. Among these, 147 (31.3%) received IV tPA in our ED, 102 (21.7%) had an absolute contraindication, and 221 (47%) had a reason to consider withholding tPA. Only 30/470 (6.4%) of potential thrombolysis patients were discovered to have international normalized ratio > or =1.7 or platelets < or =100,000/microL, and of these, 28 were suspected a priori due to known coagulopathy from medication or illness. Only 2/470 (0.4%) patients had an unsuspected coagulopathy that ultimately prevented thrombolysis.

CONCLUSIONS

Based on the experience of a large thrombolysis referral center, stroke patients without suspected clotting abnormality can safely begin thrombolytic therapy before clotting results are available. These data support the current practice guidelines, and may reassure clinicians that the benefits of early administration greatly outweigh the risks due to an unsuspected bleeding diathesis.

Silent ischemic infarcts are associated with hemorrhage burden in cerebral amyloid angiopathy

BACKGROUND

Neuropathologic studies suggest an association between cerebral amyloid angiopathy (CAA) and small ischemic infarctions as well as hemorrhages. We examined the prevalence and associated risk factors for infarcts detected by diffusion-weighted imaging (DWI).

METHODS

We performed retrospective analysis of MR images from 78 subjects with a diagnosis of probable CAA and a similar aged group of 55 subjects with Alzheimer disease or mild cognitive impairment (AD/MCI) for comparison. DWI and apparent diffusion coefficient (ADC) maps were inspected for acute or subacute infarcts. We also examined the association between DWI lesions and demographic variables, conventional vascular risk factors, and radiographic markers of CAA severity such as number of hemorrhages on gradient-echo MRI and volume of T2-hyperintense white matter lesions.

RESULTS

Twelve of 78 subjects with CAA (15%) had a total of 17 DWI-hyperintense lesions consistent with subacute cerebral infarctions vs 0 of 55 subjects with AD/MCI (p = 0.001). The DWI lesions were located primarily in cortex and subcortical white matter. CAA subjects with DWI lesions had a higher median number of total hemorrhages (22 vs 4, p = 0.025) and no difference in white matter hyperintensity volume or conventional vascular risk factors compared to subjects with CAA without lesions.

CONCLUSIONS

MRI evidence of small subacute infarcts is present in a substantial proportion of living patients with advanced cerebral amyloid angiopathy (CAA). The presence of these lesions is associated with a higher burden of hemorrhages, but not with conventional vascular risk factors. This suggests that advanced CAA predisposes to ischemic infarction as well as intracerebral hemorrhage.