Awards Abstracts 2

Pain Symptom Clusters in People with Spinal Cord Injury
Eva G. Widerström-Noga, D.D.S., Ph.D. 1,2,3; Yenisel Cruz-Almeida, MSPH 1,2 ;Elizabeth Felix, Ph.D. 1, 2
1Miami VA Medical Center, Miami, FL; 2The Miami Project to Cure Paralysis;
3Department of Neurological Surgery, University of Miami, Miller School of
Medicine, Miami, FL

Objective:
Chronic pains of various origins are prevalent in the aftermath of a SCI. Because the mechanisms generating these pains are heterogeneous, a rational approach to treating chronic pain associated with SCI should ideally be based on potential pain generating mechanisms. In order to move toward mechanism-based treatment strategies, it is necessary to translate mechanisms into signs and symptoms in people with chronic pain. The aim of the present investigation was to define clinical pain symptom clusters above, at, and below the level of injury (LOI) in persons with SCI.

Design:
Examination and interview

Participants/Methods:
People with SCI and chronic pain (n=125) went through an ASIA examination and an interview detailing each pain based on location (quality, intensity, temporal pattern and exacerbation). Exploratory factor analyses (EFA) were performed to define groupings of pain symptoms relative to LOI.

Results:
Most study participants (82.4%) experienced more than one type of pain simultaneously. These pains were mostly located at (47.6%) and below (54.1%) the LOI, whereas 16.8% were located above. Pain above the LOI was most often described as “aching” (46.8%), “sharp” (40.4%) and “stabbing” (29.8%), while “burning”, “aching”, and “sharp” were most frequently used to describe pains at and below the LOI. Pain intensity ratings did not significantly differ between pain located above (6.34±2.4), at (6.77±2.2) and below (6.38±2.3) the LOI. The EFAs revealed distinct groupings of symptoms: (1) constant, “burning” pain at or below the LOI; (2) attack-like pain aggravated by touch (mechanical allodynia) at the LOI; (3) “aching” pain aggravated by touch above the LOI.

Conclusion:
Symptom clusters including both spontaneous and evoked pain may be useful for defining subgroups of pains associated with SCI since these may indicate specific mechanisms.

Support:
This project was supported by the VA RR&D (B26566C), and the Miami Project to Cure Paralysis.

Objective:
Determine factors associated with depression in adults with pediatric-onset spinal cord injuries (SCI).

Design:
Telephone surveys

Participants/methods:
Individuals who sustained SCI at age 18 years or younger and who were 24 years of age or older at interview. A survey was conducted using a structured interview and standardized measures: Patient Health Questionnaire-9 (PHQ-9), a screening measure for depression; Functional Independence Measure (FIM-motor); Craig Handicap Assessment and Reporting Technique (CHART) to assess participation; Satisfaction with Life Scale (SWLS).

Results:
232 participants with mean age/injury 14 years(0-18), mean age/interview 31 years (24-42), 63% male, 59% tetraplegia. On the PHQ-9, 21% reported no depressive symptoms, 52% minimal symptoms, and 27% depression, ranging from mild to severe. Depression was not associated with gender, race, age/injury, age/interview, level of injury, or functional independence. Depression was associated with longer duration of injury (P=0.009) and with incomplete injuries (P=0.001). Depression was associated with poorer outcomes in several areas, including community participation (CHART), education, employment, income, and life satisfaction (SWLS). Depression was also significantly associated with more shoulder pain (P=0.041). There was a tendency for depression to be associated with spasticity (P=0.058) and pain at any site (P=0.054). Using logistic regression analysis, the strongest predictors of depression are incomplete injuries and lower scores on two subscales of the CHART.

Conclusions:
Depression is a problem for more than a fourth of adults with pediatric-onset SCI. Depression is associated with poorer outcomes in several areas. Incomplete injury is a strong risk factor, as are some aspects of community participation.

Support:
Grant # 9190 from Shriners Hospitals for Children

Objective: To evaluate cardiovascular control during orthostatic stress in individuals with chronic cervical and thoracic spinal cord injury (SCI).

Design:
Prospective clinical study.

Participants/Methods:
We studied 8 men with cervical SCI (aged 35.0±2.4 years), 8 with thoracic SCI (aged 35.4±3.6 years), and 9 able-bodied controls (aged 33.5±4.1years). We continuously recorded heart rate (HR; ECG) and beat-to-beat blood pressure (Finometer) during supine rest and following the passive assumption of an upright seated posture. Stroke volume (SV), cardiac output (CO) and total peripheral resistance (TPR) were calculated. Plasma catecholamines were determined while supine and upright. Severity of injury to motor, sensory and autonomic pathways was assessed by ASIA score and sympathetic skin responses (SSR).

Results:
Supine systolic pressure was lower in cervical SCI (cervical: 88.7±1.8; thoracic 109.9±6.1 and control: 114.9±3.8 mmHg, p<0.01). Supine HR, diastolic and mean pressures were not significantly different between groups. Supine noradrenaline (but not adrenaline) was low in cervical SCI. When upright, blood pressures increased in control and thoracic, but not in cervical SCI. HR increased when upright in all groups. The postural fall in SV and CO, and increase in TPR tended to be larger in cervical than the other two groups. Upright catecholamine levels were lower in cervical than the other two groups. Most thoracic, but not cervical, subjects had SSR in the upper extremities. One subject with thoracic SCI had absent palmar SSR (T2 ASIA A), and impaired orthostatic responses. Interestingly, one subject with cervical SCI (C4 AISA A) had preserved SSR, and showed good orthostatic cardiovascular control.

Conclusion:
Cardiovascular control during orthostasis was impaired in most cervical SCI, but rarely so in thoracic SCI. SSR may predict those subjects at greatest risk of orthostatic hypotension and impaired cardiovascular control.

Support:
Rick Hansen Man In Motion Research Foundation.

Objective:
To examine the effects of a pushrim-activated power-assist wheel (PAPAW) on physiological and perceptual responses to un-resisted and intensity-graded wheelchair propulsion in persons with SCI having significant shoulder pain.

Design:
Test, re-test with a matched control condition.

Participants/Methods:
Participants were 18 individuals aged 18-55 years with chronic paraplegia (n=12) and tetraplegia (n=6) (ASIA A/B). All participants reported shoulder pain during daily activities, which was confirmed by scores on an SCI-validated shoulder pain index. Testing was conducted on four randomized, non-consecutive days using stationary wheelchair rollers and either six minutes of un-resisted, or 12 minutes of intensity-graded wheelchair propulsion. Participants were tested in a randomized order with their own manual wheelchair and customary wheels, or the same chair and configuration adapted for PAPAWs (E-motion, Ulrich Alber GmbH & Co.) with an axel bracket. Study outcomes included oxygen consumption (VO2; L/min), propelled distance (m), energy cost of propulsion (L/m), and rating of perceived exertion (RPE; Borg Categorical 6-20 Scale).

Results:
Significant main effects of test condition were observed for VO2, L/m, and RPE in both subject groups (ps < 0.05). Subjects with paraplegia propelled 57% and 65% farther when using PAPAWs under un-resisted and intensity-graded conditions, respectively. Participants with tetraplegia using PAPAWs traveled 47% and 72% farther during the same tests, respectively. Energy cost reductions of 88% and 42% were experienced by subjects with paraplegia during un-resisted and graded propulsion with PAPAWs, respectively, while those with tetraplegia experienced reductions of 62% and 55%. In all cases, RPE was significantly lower during testing with the PAPAWs.

Conclusions:
Use of a PAPAW significantly lowers the energy cost and perceived exertion of manual wheelchair propulsion in persons with SCI having shoulder pain, while significantly increasing the propelled distance. These responses favor reduced exertional stress during wheelchair propulsion, preserved shoulder function, and enhanced independence.

Support:
This study was supported by the Miami Project to Cure Paralysis

Objective:
For high spinal cord injured patients with chronic respiratory insufficiency, electrically induced diaphragm pacing is an alternative to long-term positive pressure ventilation. The goal of this study was to demonstrate the effectiveness of a home-based ventilator weaning program after outpatient laparoscopic implantation of the DPS system.

Design:
Prospective FDA trial of the NeuRx RA/4 DPS System for electrical activation of the diaphragm for ventilatory assist in spinal cord injured patients with intact phrenic nerves.

Participants/methods:
Patients underwent laparoscopic mapping of their diaphragm to locate the phrenic nerve motor points for electrode implantation. Two weeks after surgery, stimulus/output characteristics of each electrode were determined for optimal settings. Caregivers were trained to use the DPS system and a Wright Spirometer. Progressively lengthening conditioning (weaning) sessions would involve turning off the ventilator and turning on the DPS system with documentation of time used, oxygen saturation, tidal volumes and a modified Borg scale of respiratory difficulty. Weekly electronic communication with investigators allowed for input and changes of stimulation parameters by exchange of devices.

Results:
Eighteen patients have been implanted with the DPS system. All procedures were performed on an outpatient basis with no intra-operative complications. One patient had a false positive preoperative phrenic nerve conduction study and therefore was never able to pace. The remaining 17 patients (94%) achieved greater than their predicted tidal volume during stimulation with fifteen patients undergoing weaning from the ventilator at home. Ten patients use the device full time, 6 use it 12-24 hours a day resulting in over 25 years of cumulative active implantation time. The home-based weaning protocol allows patients to maintain caregiver support, work, and significantly lower expenses.

Conclusions:
The results show the laparoscopic DPS system to be a low-risk, cost-effective outpatient system for ventilatory support with home-based weaning from the ventilator.

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