Early Experience With New Generation Deep Brain Stimulation Leads in Parkinson's Disease and Essential Tremor Patients

BACKGROUND

Newer generation deep brain stimulation (DBS) systems have recently become available in the United States. Data on real-life experience are limited. We present our initial experience incorporating newer generation DBS with Parkinson's disease (PD) and essential tremor (ET) patients. Newer systems allow for smart energy delivery and more intuitive programming and hardware modifications including constant current and directional segmented contacts.

METHODS

We compared six-month outcomes between 42 newer generation and legacy leads implanted in 28 patients. Two cohorts each included 7 PD patients with bilateral subthalamic nucleus (STN) stimulation and 7 ET patients with unilateral ventral intermediate nucleus (VIM) stimulation of the thalamus. All directional leads included 6172 Infinity 8-Channel Directional leads and Infinity internal pulse generators (Abbott Neuromodulation, Plano, TX, USA) and nondirectional leads included lead 3389 with Activa SC for VIM and PC for STN (Medtronic, Minneapolis, MN, USA).

RESULTS

Six-month outcomes for medication reduction and motor score improvements between new and legacy DBS systems in PD and ET patients were similar. Directionality was employed in 1/3 of patients. Therapeutic window (difference between amplitude when initial symptom relief was obtained and when intolerable side effects appeared with the contact being used) was significantly greater in new DBS systems in both PD (p = 0.005) and ET (p = 0.035) patients. The windows for new and legacy systems were 3.60 V ± 0.42 and 2.00 V ± 0.32 for STN and 3.06 V ± 0.44 and 1.85 V ± 0.28 for VIM, respectively.

DISCUSSION

The therapeutic window of newer systems, whether or not directionality was used, was significantly greater than that of the legacy system, which suggests increased benefit and programming options. Improvements in hardware and programming interfaces in the newer systems may also contribute to wider therapeutic windows. We expect that as we alter workflow associated with newer technology, more patients will use directionality, and amplitudes will become lower.

Characterization and Treatment of Unilateral Facial Muscle Spasm in Linear Scleroderma: A Case Report

BACKGROUND

Linear scleroderma has been associated with muscle spasms ipsilateral to skin lesions. Typically, spasms are located in trigeminal innervated muscles, leading to hemimasticatory spasm (HMS).

CASE REPORT

We report a case of linear scleroderma associated with spasm of muscles innervated not only by the trigeminal but also by the facial nerve.

DISCUSSION

We review the patient's successful treatment with incobotulinumtoxinA, a formulation of botulinum toxin that has not been reported for use in this condition.

Clinical Outcome and Characterization of Local Field Potentials in Holmes Tremor Treated with Pallidal Deep Brain Stimulation

BACKGROUND

Holmes tremor (HT) is an irregular, low-frequency rest tremor associated with prominent action and postural tremors. Currently, the most effective stereotactic target and neurophysiologic characterization of HT, specifically local field potentials (LFPs) are uncertain. We present the outcome, intraoperative neurophysiologic analysis with characterization of LFPs in a patient managed with left globus pallidus interna deep brain stimulation (Gpi DBS).

CASE REPORT

A 24-year-old male underwent left Gpi DBS for medically refractory HT. LFPs demonstrated highest powers in the delta range in Gpi. At the 6-month follow-up, a 90% reduction in tremor was observed.

DISCUSSION

Pallidal DBS should be considered as an alternative target for management of refractory HT. LFP demonstrated neuronal activity associated with higher power in the delta region, similarly seen in patients with generalized dystonia.

Prospective Study Evaluating IncobotulinumtoxinA for Cervical Dystonia or Blepharospasm: Interim Results from the First 145 Subjects with Cervical Dystonia

BACKGROUND

We report the interim results from XCiDaBLE, a large, prospective, observational "naturalistic" study evaluating Xeomin® (incobotulinumtoxinA) for Cervical Dystonia or BLEpharospasm in the United States.

METHODS

Subjects (≥ 18 years old) with cervical dystonia (CD) are followed for two treatment cycles and monitored via Interactive Voice/Web Response. The subject's physician must have chosen to treat with incobotulinumtoxinA prior to and independent of enrollment in this study. Subject-reported scales include the Subject Global Impression-Severity and Improvement and Cervical Dystonia Impact Profile (CDIP-58), and Work Productivity and Quality of Life (QoL) are assessed by means of an employment questionnaire and work history and the SF-12v2 Health Survey (SF-12v2). Subjects are seen by the investigator for three visits, which include a baseline visit (including the first injection), a second injection visit, and a final study visit (12 weeks after the second injection).

RESULTS

This ongoing study includes 145 subjects with a diagnosis of CD. The majority were female (82.3%) and white (91.0%) and had previously been treated with botulinum toxins (77.2%). There were 106 employed at the time of disease onset, but 12.6 years later only 44% were still employed at the time of enrolment into the study, and 20% were either receiving or seeking disability benefits. The mean total dose/treatment of CD was 225.2 units for the first injection. The CDIP-58 total score was significantly improved 4 weeks after the first injection compared to baseline (p≤0.0001). Most subjects noted improvement in their global impression assessment. No new or unexpected adverse events occurred.

DISCUSSION

The results from these interim analyses confirm previous controlled, single-dose studies of incobotulinumtoxinA in terms of efficacy and safety.

Epsilon-sarcoglycan mutations found in combination with other dystonia gene mutations

Myoclonus-dystonia is a movement disorder associated with mutations in the epsilon-sarcoglycan gene (SGCE) in most families and in the DRD2 and DYT1 genes in two single families. In both of the latter families, we also found a mutation of SGCE. The molecular mechanisms through which the detected mutations may contribute to myoclonus-dystonia remain to be determined.

Clinical findings of a myoclonus-dystonia family with two distinct mutations

Myoclonus-dystonia has recently been associated with mutations in the epsilon-sarcoglycan gene (SCGE) on 7q21. Previously, the authors reported a patient with myoclonus-dystonia and an 18-bp deletion in the DYT1 gene on 9q34. The authors have now re-evaluated the patient harboring this deletion for mutations in the SGCE gene and identified a missense change. In the current study, the authors describe the clinical details of this family carrying mutations in two different dystonia genes. Further analysis of these mutations separately and together in cell culture and in animal models should clarify their functional consequences.

Parkinson's disease. Therapeutic strategies to improve patient function and quality of life

Idiopathic Parkinson's disease (PD) is an age-related neuro-degenerative disorder characterized by slowness, stiffness, resting tremor, gait impairment, and postural instability. Levodopa is the most potent pharmacologic agent for symptom management and is associated with an increase in quality of life and longevity for patients with PD, but chronic use causes motor complications. The availability of several newer types of agents--dopamine agonists, monoamine oxidase inhibitors, and catechol-O-methyltransferase inhibitors--gives physicians increased flexibility with regard to first-line therapy, adjunct therapy, and managing or reducing the frequency of motor complications and other side effects associated with chronic levodopa therapy.

The role of somatosensory evoked potentials in the diagnosis of AIDS-associated myelopathy

BACKGROUND

Although AIDS-associated vacuolar myelopathy is detected in >50% of autopsy cases, it is often unrecognized during life. The clinical assessment is often difficult because of concurrent peripheral neuropathy and lack of specific diagnostic markers. Somatosensory evoked potentials (SEPs) have been successfully used to evaluate central conduction in a number of diseases involving the spinal cord.

OBJECTIVES

To assess the diagnostic yield of SEPs in AIDS-associated myelopathy.

METHODS

We recorded tibial and median nerve SEPs in 69 HIV-infected subjects referred for evaluation of lower extremity neurologic abnormalities. Stimulation of the peroneal nerve at the popliteal fossa was performed in patients with absent response to ankle stimulation.

RESULTS

HIV-infected subjects had significantly delayed latencies of both peripheral and central potentials, suggesting a combination of peripheral and CNS abnormalities. Analysis of peripheral and central latencies allowed us to discriminate between neuropathy and myelopathy in individual patients. Abnormalities of tibial central conduction time (CCT) correlated with clinical diagnosis of myelopathy. There was no significant difference in median CCTs between patients and controls, suggesting that conduction abnormalities were restricted to the thoracolumbar spinal cord. A derived spinal conduction time was a sensitive indicator of central conduction abnormalities in AIDS patients with myelopathy.

CONCLUSIONS

The combination of median, posterior tibial, and peroneal SEPs is a valuable tool in the diagnosis of AIDS-associated myelopathy, particularly when myelopathy and peripheral neuropathy coexist. The use of a derived spinal conduction time improves the diagnostic yield of SEPs in AIDS-associated myelopathy.

MR findings in AIDS-associated myelopathy

BACKGROUND AND PURPOSE

The most common cause of spinal cord disease among patients with AIDS or those infected with HIV-1 is AIDS-associated myelopathy. The purpose of this study was to determine the MR characteristics of the spinal cord in this patient population and to correlate these findings with the clinical severity of myelopathy.

METHODS

MR images of the spinal cord in 21 patients with documented HIV-1 infection or AIDS and a clinical diagnosis of AIDS-associated myelopathy were assessed retrospectively for atrophy, intrinsic signal abnormality, and abnormal enhancement. The clinical severity of myelopathy was graded by a neurologist on the basis of physical examination, and a qualitative correlation was made with the MR findings.

RESULTS

MR findings were abnormal in 18 of the 21 patients. The most common feature was spinal cord atrophy (n = 15), typically involving the thoracic cord with or without cervical cord involvement, followed by intrinsic cord signal abnormality (n = 6), and normal-appearing cord (n = 3). Three patients had both cord atrophy and intrinsic cord signal abnormality. The cord signal abnormality was diffuse, without predilection for any specific distribution pattern. Enhancement was not seen in any of the 10 patients who received intravenous contrast material. Only one of 16 patients with moderate to severe myelopathy had normal MR findings, as compared with two of five patients with mild myelopathy.

CONCLUSION

MR findings in the spinal cord are abnormal in the majority of patients with AIDS-associated myelopathy, typically showing spinal cord atrophy, with or without intrinsic cord signal abnormality. Patients with moderate to severe myelopathy have an increased frequency of spinal cord abnormalities, but a definite correlation between clinical severity of myelopathy and extent of MR abnormalities remains to be established.

A pilot study of L-methionine for the treatment of AIDS-associated myelopathy

The pathogenesis of AIDS-associated vacuolar myelopathy (VM) may be related to abnormality of transmethylation mechanisms in the nervous system. To evaluate the safety and potential efficacy of the methyl-group donor L-methionine in AIDS-associated VM, we conducted a pilot clinical trial in 12 patients with VM. Seven of the nine patients who completed the study had clinical and electrophysiologic improvement. Controlled studies may be indicated to assess the efficacy and safety of L-methionine in AIDS-associated VM.

A new noninvasive technique for imaging atherosclerotic plaque in the aortic arch of stroke patients by transcutaneous real-time B-mode ultrasonography: an initial report

BACKGROUND AND PURPOSE

Aortic arch atherosclerotic plaque is a probable source of atheroembolic stroke. Transesophageal echocardiography (TEE) has been used to image the aorta of patients with stroke to identify atherosclerotic plaque. TEE is moderately invasive and does not always visualize plaques present in the distal ascending aorta and proximal aortic arch.

METHODS

In the current study, transcutaneous B-mode ultrasonography was performed to image the aortic arch through a lateral supraclavicular window, and the results were compared with those of TEE in 20 patients. The aorta was subdivided into the proximal ascending (PAsc), distal ascending (DAsc), proximal aortic arch (PAA), and distal aortic arch (DAA) to be certain the plaques identified by each technique were the same. Plaques were characterized as simple (<4 mm thick) or complex (>4 mm thick).

RESULTS

In the PAsc, 8 simple plaques were identified with TEE but not with B-mode. In the DAsc, 1 complex plaque was identified with both techniques, and B-mode identified 1 additional complex and 1 simple plaque. In the PAA, 6 simple and 5 complex plaques were identified by both techniques, and TEE identified 1 additional complex plaque. In the DAA, TEE identified 2 simple and 2 complex plaques; B-mode identified 3 complex plaques.

CONCLUSIONS

B-mode imaging compared favorably with TEE in identification of plaques in the aortic arch and distal ascending aorta, although it could not identify simple plaques in the proximal ascending. B-mode could visualize plaques not seen by TEE in the distal ascending aorta. B-mode ultrasonography is complementary to TEE in performance of a comprehensive assessment of plaque in the aortic arch and provides a noninvasive method for sequential studies of plaques that can be visualized.