Epidural Spinal Electrical Stimulation Research Articles

Epidural Electrical Stimulation of the Lumbosacral Spinal Cord Improves Trunk Stability During Seated Reaching in Two Humans With Severe Thoracic Spinal Cord Injury

Background: Quality of life measurements indicate that independent performance of activities of daily living, such as reaching to manipulate objects, is a high priority of individuals living with motor impairments due to spinal cord injury (SCI). In a small number of research participants with SCI, electrical stimulation applied to the dorsal epidural surface of the spinal cord, termed epidural spinal electrical stimulation (ES), has been shown to improve motor functions, such as standing and stepping. However, the impact of ES on seated reaching performance, as well as the approach to identifying stimulation parameters that improve reaching ability, have yet to be described.Objective: Herein, we characterize the effects of ES on seated reaching performance in two participants with chronic, complete loss of motor and sensory functions below thoracic-level SCI. Additionally, we report the effects of delivering stimulation to discrete cathode/anode locations on a 16-contact electrode array spanning the lumbosacral spinal segments on reach distance while participants were seated on a mat and/or in their wheelchair.Methods: Two males with mid-thoracic SCI due to trauma, each of which occurred more than 3 years prior to study participation, were enrolled in a clinical trial at Mayo Clinic, Rochester, MN, USA. Reaching performance was assessed, with and without ES, at several time points throughout the study using the modified functional reach test (mFRT). Altogether, participant 1 performed 1,164 reach tests over 26-time points. Participant 2 performed 480 reach tests over 17-time points.Results: Median reach distances during ES were higher for both participants compared to without ES. Forward reach distances were greater than lateral reach distances in all environments, mat or wheelchair, for both participants. Stimulation delivered in the caudal region of the array resulted in improved forward reach distance compared to stimulation in the rostral region. For both participants, when stimulation was turned off, no significant changes in reach distance were observed throughout the study.Conclusion: ES enhanced seated reaching-performance of individuals with chronic SCI. Additionally, electrode configurations delivering stimulation in caudal regions of the lumbosacral spinal segments may improve reaching ability compared to rostral regions.

Interfacing With Alpha Motor Neurons in Spinal Cord Injury Patients Receiving Trans-spinal Electrical Stimulation.

Trans-spinal direct current stimulation (tsDCS) provides a non-invasive, clinically viable approach to potentially restore physiological neuromuscular function after neurological impairment, e.g., spinal cord injury (SCI). Use of tsDCS has been hampered by the inability of delivering stimulation patterns based on the activity of neural targets responsible to motor function, i.e., α-motor neurons (α-MNs). State of the art modeling and experimental techniques do not provide information about how individual α-MNs respond to electrical fields. This is a major element hindering the development of neuro-modulative technologies highly tailored to an individual patient. For the first time, we propose the use of a signal-based approach to infer tsDCS effects on large α-MNs pools in four incomplete SCI individuals. We employ leg muscles spatial sampling and deconvolution of high-density fiber electrical activity to decode accurate α-MNs discharges across multiple lumbosacral segments during isometric plantar flexion sub-maximal contractions. This is done before, immediately after and 30 min after sub-threshold cathodal stimulation. We deliver sham tsDCS as a control measure. First, we propose a new algorithm for removing compromised information from decomposed α-MNs spike trains, thereby enabling robust decomposition and frequency-domain analysis. Second, we propose the analysis of α-MNs spike trains coherence (i.e., frequency-domain) as an indicator of spinal response to tsDCS. Results showed that α-MNs spike trains coherence analysis sensibly varied across stimulation phases. Coherence analyses results suggested that the common synaptic input to α-MNs pools decreased immediately after cathodal tsDCS with a persistent effect after 30 min. Our proposed non-invasive decoding of individual α-MNs behavior may open up new avenues for the design of real-time closed-loop control applications including both transcutaneous and epidural spinal electrical stimulation where stimulation parameters are adjusted on-the-fly.

Epidural and transcutaneous spinal electrical stimulation for restoration of movement after incomplete and complete spinal cord injury.

The Purpose of this review is to outline and explain the therapeutic use of electrical spinal cord stimulation (SCS) for modification of spinal motor output. Central functional stimulation provides afferent input to posterior root neurons and is applied to improve volitional movements, posture and their endurance, control spasticity, and improve bladder function or perfusion in the lower limbs. Clinical accomplishments strongly depend on each individual's physiological state and specific methodical adaptation to that physiological state. Effectiveness of this neuromodulory technique for changing motor control after spinal cord injury (SCI) continues to be explored along with the underlying mechanisms of its effect in people with complete and incomplete spinal cord injuries. There are extensive studies of tonic and rhythmical activity elicited from the lumbar cord as well as data demonstrating augmentation of residual volitional activity. Recent studies have focused on verifying if and how SCS can modify features of neurocontrol in ambulatory spinal cord patients. In this review, we emphasize recent publications of research revealing that SCS can substitute for the reduced brain drive for control of excitability in people with SCI. Artificially replacing diminished or lost brain control over the spinal cord has limitations. A fundamental requirement for successful SCS application is analysis of each individual's residual postinjury neural function. This will allow a better understanding of the physiological interactions between SCS and spinal cord motor control below injury and provide criteria for its application. Finally, the publication of both successful and failed applications of SCS will be crucial for gaining future progress.

Treatment of Severe Arterial Occlusive Disease by Epidural Spinal Electrical Stimulation

In 10 cases with advanced vascular occlusive disease the effect of epidural spinal electrical stimulation (ESES) on peripheral circulation has been tested by use of transcutaneous oxygen measurement (TcPO2), telethermography, and laser-speckle measurements. The values in all cases increased. Improvement was more pronounced during the first two to three weeks. Indications and limitations of this treatment modality are discussed.

Epidural spinal electrical stimulation for severe angina: a study of its effects on symptoms, exercise tolerance and degree of ischaemia

The effectiveness of epidural spinal electrical stimulation has been studied in 14 patients with severe intractable angina unresponsive to standard therapies including bypass grafting. After implantation of the neurostimulator units the patients were assessed by a symptom questionnaire, treadmill exercise testing and right atrial pacing. There was a significant improvement of symptoms and GTN consumption fell markedly. With the neurostimulator on, exercise duration increased from a mean (CI) of 414 (153) to 478 (149) s, and total ST segment depression was less both at maximum exercise (7.1 (4.5) vs 5.6 (4.2) mm) and at 90% of the maximum control heart rate (3.5 (3.7) vs 2.6 (4.3) mm), with similar rate-pressure product at maximum exercise. With right atrial pacing the maximum heart rate reached before onset of angina was increased (143 (14) to 150 (7) b.min-1) and total ST segment depression was less at all heart rates. Benefit has persisted in some patients for over 2 years without any apparent adverse sequelae. Epidural spinal electrical stimulation is, therefore, an alternative therapy for some patients with intractable angina which has not responded to standard therapies.

Epidural Lead Fracture Caused by Material Processing Fault

Fracture of the epidural lead (Pisces Quad 3487) is documented in four out of eight patients with an implanted Itrel pacing system for treatment of peripheral vascular disease. In two patients, lead fracture was established during x-ray fluoroscopy. In the remaining two patients, x-ray examination did not reveal any fracture, due to proximity of the fragments. Microscopic examination of the extracted lead, however, confirmed lead fracture, as well as the presence of tissue fluid and thrombus between the two ends of the spiral shaped lead, but no insulation defect was observed. A cross-sectional area on the fracture line of the broken lead was examined using scanning electron microscopy. It was found, by tracing the radial marks to their point of convergence, that the initial microcrack started from a large inclusion of the calcium-silicon type at the lead surface. The initial microcrack was propagated by the fatigue mechanism. The presence of a large inclusion at the surface suggests that the main cause of the failure of the investigated epidural leads could be improper fabrication of the material. The high incidence of epidural lead fracture in our group suggests that this complication should be considered as a possible cause of epidural spinal electrical stimulation pacing system dysfunction.

Myocardial release of endogenous opioids in the human heart and the effects of epidural spinal electrical stimulation (ESES) in pacing-induced angina pectoris

Myocardial release of endogenous opioids in the human heart and the effects of epidural spinal electrical stimulation (ESES) in pacing-induced angina pectoris

Physical, psychological and social function in chronic pain patients after epidural spinal electrical stimulation

Physical, psychological and social function in chronic pain patients after epidural spinal electrical stimulation

Epidural spinal electrical stimulation in the treatment of severe arterial occlusive disease

Epidural spinal electrical stimulation in the treatment of severe arterial occlusive disease

Myocardial release of endogenous opioids in human heart and the effects of epidural spinal electrical stimulation (ESES) in pacing-induced angina pectoris

Myocardial release of endogenous opioids in human heart and the effects of epidural spinal electrical stimulation (ESES) in pacing-induced angina pectoris

Clinical effects of epidural spinal electrical stimulation (ESES) in angina pectoris — Effect on arrhythmia, myocardial perfusion and clinical long term effects

Clinical effects of epidural spinal electrical stimulation (ESES) in angina pectoris — Effect on arrhythmia, myocardial perfusion and clinical long term effects

Epidural spinal electrical stimulation in severe angina pectoris.

The short term effects of epidural spinal electrical stimulation were studied in 10 patients with angina pectoris of New York Heart Association functional class III or IV. The antianginal pharmacological treatment given at entry to the study was regarded as optimal and was not changed during the study. The effects of epidural spinal electrical stimulation were measured by repeated bicycle ergometer tests. Treatment with epidural spinal electrical stimulation increased the patients' working capacity, decreased ST segment depression, increased time to angina, and reduced the recovery time. The observed effects did not seem to be correlated with any changes in myocardial oxygen demand during epidural spinal electrical stimulation and were additional to the benefits of the pharmacological treatment.

Long-term results by epidural spinal electrical stimulation (ESES) in patients with inoperable severe lower limb ischaemia

Arterial reconstruction is the treatment of choice for patients with severe lower limb ischaemia, but may at times be technically impossible. Thirty-two consecutive patients with impending (n = 24) or already established (n = 8) distal arteriosclerotic or diabetic lower limb gangrene, in whom vascular surgery was either technically impossible or had failed, were treated with epidural spinal electrical stimulation (ESES) for 27 +/- 16 (S.D.) months. All patients had severe rest pain, which was reduced by ESES in 91% of the cases. Improved ulcer healing was noted in 58% of the patients who had skin ulceration. Eighty-three percent of those patients who did not have established gangrene when ESES was started, retained their leg after 1 year, and 54% after 3 years. These results suggest that ESES often provides pain relief and improves skin healing in patients with impending arteriosclerotic or diabetic gangrene in whom vascular surgery is impossible or has failed. Epidural spinal electrical stimulation (ESES) does not affect the progression of established gangrene but may provide pain relief. The observed outcome of severe limb ischaemia in this study could be used to compare with those after arterial reconstruction performed in patients with poor run-off vessels, and may allow us to examine the natural history of this disease when adequate pain relief is provided. The results reported here and the previously reported enhancement of cutaneous blood flow in severely ischaemic extremities by ESES may suggest, that ESES enhances limb salvage by improving skin blood flow.

Epidural Spinal Electrical Stimulation in Peripheral Vascular Disease

Epidural spinal electrical stimulation (ESES) has been valuable in the control of pain arising from peripheral vascular disease. Thirty-two of 34 patients experience some relief of pain and 12 of 24 patients showed healing of ischemic ulcers. This technique may prove to be useful in preventing or delaying amputation of ischemic limbs. A prospective randomized study has been undertaken to assess whether this form of electrical stimulation can save limbs.

Physical, Psychologic, and Social Function in Chronic Pain Patients After Epidural Spinal Electrical Stimulation

The overall function, pain, and mood disturbance of 54 patients with benign chronic pain were studied as to their response to epidural spinal electrical stimulation (ESES) more than 12 months after the implantation of ESES electrodes. Both responder (n = 23) and nonresponder (n = 31) pain patients demonstrated extensively worse physical and psychosocial function on the Sickness Impact Profile (SIP) and worse self-rated mood disturbance on the Mood Adjective Check List (MACL) than a control population sample. Responders to ESES were insignificantly less impaired in physical functions of daily life than nonresponders, but clearly less inhibited in the social pattern of contact. Self-rated pain sensation differed 36% between responders and nonresponders, and the pain measures of all pain patients correlated with total mood disturbance on the MACL and with its dimensions for depression and fatigue. Social characteristics, sex, diagnoses, comorbidity, and duration of pain did not discriminate. In a supplementary prospective short-term study, pain ratings had improved by 30% 3 weeks after implantations. The night sleep and general psychic balance (SIP category emotional behavior) were then also significantly improved. A shortened SIP version of 8 items optimizing responder-nonresponder differences and 12 items of mood disturbance are suggested to supplement pain ratings for overall assessment of chronic pain patients. A wider usage of ESES is recommended for pain patients who can comply to the regimen, because the surgical technique is now simple and safe.

Epidural electrical stimulation in severe limb ischemia. Pain relief, increased blood flow, and a possible limb-saving effect.

Peripheral vascular disease of the extremities causes ischemic pain and, at times, skin ulcerations and gangrene. It has been suggested that epidural spinal electrical stimulation (ESES) could improve peripheral circulation. Since 1978 we have used ESES in 34 patients with severe limb ischemia; all had resting pain and most had ischemic ulcers. Arterial surgery was technically impossible. Twenty-six patients had arteriosclerotic disease, one had Buerger's disease, and seven had severe vasospastic disorders. Ninety-four per cent of the patients experienced pain relief. ESES healed ulcers in 50% of those with preoperative nonhealing skin ulcerations. Seventy per cent of the patients showed improved skin temperature recordings. Only 38% of the stimulated arteriosclerotic patients underwent amputations during a mean followup period of 16 months, as compared to 90% of a comparable group of unstimulated patients. ESES is very promising in severe limb ischemia where reconstructive surgery is impossible or has failed.