Kath M. Bogie

Clinical Applications of Electrical Stimulation After Spinal Cord Injury

Abstract Summary: During the last one-half century, electrical stimulation has become dinically significant for improving health and restoring useful function afterspinal cord injury. Short-term stimulation can be provided by electrodes on the skin or percutaneous fine wires, but implanted systems are preferable for long-term use. Electrical stimulation of intact lower motor neurons can exercise paralyzed musdes and reverse wasting; improve strength, endurance, and cardiovascular fitness; and may reduce the progression of osteoporosis. Other potential therapeutic uses being investigated indude reduction of spasticity, prevention of deep vein thrombosis, and improvement of tissue health. Pacing of intact phrenic nerves in high tetraplegia can produce effective respiration without mechanical ventilation, allowing improved speech, increased mobility, and increased sense of well-being. lmprovement of cough has also been demonstrated. Stimulation of intact sacral ne.rves can produce effective micturition and reduce urinary tract infection; it can also improve bowel function and erection. lt is usually combined with posterior sacral rhizotomy to improve continence and bladder capacity, and the combination has been shown to reduce costs of care. Electroejaculation can now produce semen in most men with spinal cord injury. Significant achievements have also been made in restoring limb function . Useful hand grasp can be provided in CS and C6 tetraplegia, reducing dependence on adapted equipment and assistants. Standing, assistance with transfers, and walking for short distances can be provided to selected persons with paraplegia, improving their access to objects, places, and opportunities that are inaccessible from a wheelchair. This review summarizes the current state of therapeutic and neuroprosthetic applications of electrical stimulation afterspinal cord injury and identifies some future directions of research and dinical and commercial development.

Effects of regular use of neuromuscular electrical stimulation on tissue health.

Changes in tissue health were monitored in a group of spinal cord injury (SCI) individuals with the use of an implanted neuromuscular electrical stimulation (NMES) system to provide standing and to facilitate standing transfers. Tissue health was evaluated through monitoring tissue oxygen levels in the ischial region along with measuring interface pressures at the seating support interface. Baseline assessments were done at study enrollment and repeated on completion of a conditioning exercise program. Serial assessments of tissue health were performed on eight NMES implant recipients. Unloaded tissue oxygen levels in the ischial region tended to increase after following the NMES exercise program for 8 weeks. Concurrently, pressure distributions at the seating support interface tended to change such that although the total pressure acting at the interface did not change, ischial region pressures showed a significant decrease. These changes indicate that chronic use of NMES has a quantifiable benefit on tissue health.

Functional Electrical Stimulation and Spinal Cord Injury

Spinal cord injuries (SCI) can disrupt communications between the brain and the body, resulting in loss of control over otherwise intact neuromuscular systems. Functional electrical stimulation (FES) of the central and peripheral nervous system can use these intact neuromuscular systems to provide therapeutic exercise options to allow functional restoration and to manage medical complications following SCI. The use of FES for the restoration of muscular and organ functions may significantly decrease the morbidity and mortality following SCI. Many FES devices are commercially available and should be considered as part of the lifelong rehabilitation care plan for all eligible persons with SCI.

New technique for real-time interface pressure analysis: Getting more out of large image data sets

Recent technological improvements have led to increasing clinical use of interface pressure mapping for seating pressure evaluation, which often requires repeated assessments. However, clinical conditions cannot be controlled as closely as research settings, thereby creating challenges to statistical analysis of data. A multistage longitudinal analysis and self-registration (LASR) technique is introduced that emphasizes real-time interface pressure image analysis in three dimensions. Suitable for use in clinical settings, LASR is composed of several modern statistical components, including a segmentation method. The robustness of our segmentation method is also shown. Application of LASR to analysis of data from neuromuscular electrical stimulation (NMES) experiments confirms that NMES improves static seating pressure distributions in the sacral-ischial region over time. Dynamic NMES also improves weight-shifting over time. These changes may reduce the risk of pressure ulcer development.

Crowdsourcing Awareness: Exploration of the Ovarian Cancer Knowledge Gap through Amazon Mechanical Turk

Background Ovarian cancer is the most lethal gynecologic disease in the United States, with more women dying from this cancer than all gynecological cancers combined. Ovarian cancer has been termed the “silent killer” because some patients do not show clear symptoms at an early stage. Currently, there is a lack of approved and effective early diagnostic tools for ovarian cancer. There is also an apparent severe knowledge gap of ovarian cancer in general and of its indicative symptoms among both public and many health professionals. These factors have significantly contributed to the late stage diagnosis of most ovarian cancer patients (63% are diagnosed at Stage III or above), where the 5-year survival rate is less than 30%. The paucity of knowledge concerning ovarian cancer in the United States is unknown. Methods The present investigation examined current public awareness and knowledge about ovarian cancer. The study implemented design strategies to develop an unbiased survey with quality control measures, including the modern application of multiple statistical analyses. The survey assessed a reasonable proxy of the US population by crowdsourcing participants through the online task marketplace Amazon Mechanical Turk, at a highly condensed rate of cost and time compared to traditional recruitment methods. Conclusion Knowledge of ovarian cancer was compared to that of breast cancer using repeated measures, bias control and other quality control measures in the survey design. Analyses included multinomial logistic regression and categorical data analysis procedures such as correspondence analysis, among other statistics. We confirmed the relatively poor public knowledge of ovarian cancer among the US population. The simple, yet novel design should set an example for designing surveys to obtain quality data via Amazon Mechanical Turk with the associated analyses.

The use of sensory electrical stimulation for pressure ulcer prevention.

Pressure ulcer prevention is critically important for many people with reduced mobility. The authors investigated whether sensory (sub-motor-threshold) electrical stimulation (ES) may provide a convenient preventive intervention. A double-blinded, repeated measures study design was used to test the hypothesis that repeated use of sensory surface ES improves tissue health status in individuals with motor paralysis. Six adult males with complete spinal cord injury (SCI) were randomly assigned to treatment or control groups. The treatment group received the ES intervention, whereas the control group received a control sham intervention. Repeated tissue health assessments included transcutaneous oxygen tension (TcPO2), interface pressure mapping, and gluteal computed tomography (CT) studies. An initial increase in TcPO2 following use of subthreshold ES was observed but was not sustained at follow-up. No statistically significant changes before and after treatment were found in regional TcPO2, gluteal muscle area or pressure distribution. Thus subthreshold ES does not appear to have any sustained effects on tissue health status indicative of reduced pressure ulcer risk for individuals with SCI. This implies that a contractile muscle response is critically important and further that subthreshold ES is unlikely to prevent pressure ulcers. Further studies are needed to find solutions for preventing pressure ulcers in high-risk populations.

The Effects of Combined Trunk and Gluteal Neuromuscular Electrical Stimulation on Posture and Tissue Health in Spinal Cord Injury

To investigate whether combined trunk and gluteal neuromuscular electrical stimulation (NMES) alters seated posture and improves pelvic tissue health in persons with a spinal cord injury.

Physiological measurements of tissue health; implications for clinical practice

Pressure mapping alone insufficiently describes tissue health. Comprehensive, quantitative non invasive assessment is crucial. Interface pressures (IPs) and transcutaneous blood gas levels [transcutaneous tissue oxygen (TcPO2)] were simultaneously assessed over both ischia and the sacrum to investigate the hypotheses: (i) tissue oxygenation decreases with sustained applied pressure; (ii) tissue oxygen and IP are inversely correlated in loaded soft tissues; (iii) multisite assessments are unnecessary because healthy individuals are symmetrical. Measurements were taken at 5‐minute intervals for 20 minutes in both sitting and supine lying for a cohort of 20 able‐bodied adults. There were no statistically significant changes over time for either variable in 96% of timepoint comparisons. Specifically, no significant differences were seen between 10 and 20 minutes in either position. These findings imply that a 10‐minute assessment can reliably indicate tissue health and that tissue may adapt to applied load over time. No statistically significant correlations between TcPO2 and IP were observed. However, the left and right ischia were significantly different for both variables in supine lying (P < 0·001) and for sitting IP (P < 0·010). Thus, even in this healthy cohort, postural symmetry was not observed and should not be assumed for other populations with restricted mobility. If a multisite technique cannot be used, repeated tissue health assessments must use the same anatomic location.

Pulsatile Lavage for the Enhancement of Pressure Ulcer Healing: A Randomized Controlled Trial

Background Pressure ulcer development is a common, serious complication after spinal cord injury (SCI). Although many biophysical agents are available for treatment, few randomized controlled trials of their efficacy have been done. Objective The study objective was to examine the efficacy of low-pressure pulsatile lavage treatment for stage III and IV pressure ulcers in people with SCI. Design This study was a randomized controlled trial. Participants and assessors were unaware of intervention assignments. Setting This study was conducted in an SCI tertiary care center inpatient unit. Participants Participants were 28 people with SCI and stage III and IV pelvic pressure ulcers; 14 participants each were randomly assigned to treatment and control (sham treatment) groups. Intervention Daily low-pressure pulsatile lavage treatment with 1 L of normal saline at 11 psi of pressure was applied to the treatment group along with standard dressing changes. The control group received only sham treatment and standard dressing changes. Measurements Linear and volume measurements of pressure ulcer dimensions were obtained weekly for 3 weeks. Results Statistical analysis with the t test revealed no statistically significant difference in demographics between groups. Random-coefficient models for analysis of linear and volume measurements revealed improvements over time for both groups. Time trend analysis revealed greater measurement decreases for the treatment group. Differences in rates of change (with 95% confidence intervals) for treatment and control groups, respectively, were: depth, −0.24 (0.09 to −0.58) cm/wk; width, −0.16 (0.06 to −0.39) cm/wk; length, −0.47 (0.18 to −1.12) cm/wk; and volume, −0.33 (0.13 to −0.80) cm3/wk. Limitations Study limitations were small sample size and inclusion of only one site. Additionally, participants were not queried about their group assignments. Conclusions Pulsatile lavage enhanced stage III and IV pelvic pressure ulcer healing rates in people with SCI relative to standard pressure ulcer treatment alone.

Assessment of Gluteus Maximus Muscle Area With Different Image Analysis Programs

OBJECTIVE To determine the effectiveness of a percutaneous gluteal stimulation system (GSTIM) by comparing assessments of axial computed tomography (CT) scans for the pelvic area. DESIGN Comparing the measurements of the cross-sectional area (CSA) of the gluteus maximus muscle between raters and 2 image analysis programs. SETTING Retrospective axial CT scans of the pelvic area. PARTICIPANTS Men (N=9) with complete (below T6) spinal cord injury (SCI) and at least 2 years postinjury participated in the study (range, 29-75y; mean age, 51.8y). INTERVENTION Comparing gluteus maximus CSA before and after a period of GSTIM. MAIN OUTCOME MEASURE Measurements made by 2 expert and 2 nonexpert raters were used to compare the repeatability and reliability of measuring muscle CSA. The longitudinal study presented is from repeated CT scans obtained over a 2-year period for 1 representative participant who received a GSTIM system. RESULTS For repeatability, nonexpert raters measured a mean CSA of 35.2 cm2 (range, 20-45 cm2), while experts measured 21 cm2 (range, 10-35 cm2). A composite of all raters using the same program had SDs of 2.5 to 2.6 cm2 for a program available through the National Institutes of Health and 2.5 to 4.4 cm2 for a commercially available program. For reliability, differences between the 2 programs had mean differences in SD between 2.2 and 3.7 cm2. CONCLUSIONS The same rater and program (preferably the more reliable ImageJ) is recommended for the course of a longitudinal study. Otherwise, significant error would be introduced. Furthermore, significant increases in the CSA of gluteal muscle compared with preintervention (baseline) measurements were observed for the participant receiving GSTIM.