Poster 49: A Radiographically Verified, Discontinuous Lumbar Catheter May Still Deliver Intrathecal Baclofen: A Case Report

CONGRESS ANNUAL CONFERENCE ABSTRACTS

poral changes in spinal excitability after administering bolus via lumbar puncture at a lower concentration and via implanted catheter at a higher concentration. Design: Before-after study. Setting: Tertiary care rehabilitation center. Participants: 7 candidates and 7 recipients of ITB pump for spasticity. Interventions: 50-␮g ITB bolus administered via lumbar puncture at 50␮g/mL (2min) to pump candidates and via implanted catheter at 500␮g/mL (10min) to recipients. Main Outcome Measures: Bilateral soleus H-reflex and M-wave amplitude ratio (H/M) before, 1 hour, and 2 hours after ITB bolus. Results: Baseline H/M were significantly (P⬍.05) higher in candidates (59%⫾21%) versus recipients (36%⫾25%) receiving 68⫾38␮g/d of continuous ITB. At 1 and 2 hours after bolus, H/M decrease relative to baseline did not differ significantly between groups (lumbar puncture: 25%⫾16% and 4%⫾3%; implanted catheter: 35%⫾22% and 12%⫾11%, respectively). Linear slopes of H/M change over 2 hours were comparable (lumbar puncture, ⫺.48⫾.15; implanted catheter, ⫺.48⫾.17). Conclusions: Temporal H/M profiles within 2 hours of ITB bolus administration indicate similar changes in spinal reflex excitability despite different mode of administration and 10-fold concentration gradient. Catheter location and profound H/M sensitivity to a 50␮g ITB bolus potentially confounded these findings. We reaffirm H/M sensitivity for ITB monitoring and potential troubleshooting applications. Key Words: Baclofen; Muscle spasticity; Rehabilitation. Poster 48 Muscle Activation Response to Electric Stimulation Intensity for Motor Complete Spinal Cord Injury. Gail Forrest (Kessler Medical Rehabilitation Research and Education Center, West Orange, NJ), Pouran Faghri, Mathew Yarossi, Erics Garbarini, Sue Ann Sisto, Susan Harkema. Disclosure: None declared. Objective: To evaluate the electromyographic response curve to incremental increases in electric stimulation intensity applied to the rectus femoris of persons with motor complete spinal cord injury (SCI). Design: Case study (n⫽2). Setting: Human performance and movement laboratory. Participants: 2 participants with American Spinal Injury Association grade B injuries, who were 3.5 years postinjury and 100% wheelchair reliant. Interventions: Surface electromyographic data were collected from the right rectus femoris of 2 participants during electric stimulation. Symmetrical biphasic pulses of 300␮s at 35Hz delivered across a 1000⍀ load, were applied bilaterally on the rectus femoris while subjects were supine and standing (using an overhead harness with body weight support). While supine, threshold electric stimulation intensity was 6mA and was increased 2mA every 5 seconds. Main Outcome Measures: An electromyographic response curve: electromyographic data were low-pass filtered sequentially at 35Hz and 7Hz using a fourth-order zero-lag digital Butterworth filter. Filtered data were averaged over each 5-second interval. Results: We were able to differentiate an electromyographic response curve to different electric stimulation intensity. The amplitude reached a plateau (51⫾7.01mA, n⫽2) as electric stimulation increased (65⫾7.01mA), possibly indicating fatigue. Conclusions: An electromyographic/muscle dose response curve to incremental changes in electric stimulation was observed for the subjects with motor complete SCI. Further, the maximum electromyographic response plateaued at high electric stimulation intensity. This protocol may enable clinicians to quantify suitable electric stimulation parameters utilizing an electromyographic response curve to induce proper muscle contraction and prevent undue fatigue. Key Words: Electric stimulation, Electromyography; Rehabilitation; Spinal cord injuries.

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Poster 49 A Radiographically Verified, Discontinuous Lumbar Catheter May Still Deliver Intrathecal Baclofen: A Case Report. Stuart Yablon (Methodist Rehabilitation Center, Jackson, MS), Dobrivoje Stokic, John Lancon. Disclosure: None declared. Complications associated with intrathecal baclofen (ITB) administration frequently involve the catheter. Radiographically discontinuous catheters are assumed to be “broken,” that is, not capable of administering the drug. This case report challenges this assumption, which may have important treatment implications. An adult with profound motor and communication impairments due to cerebral palsy was hospitalized 29 months after ITB pump implant with new onset of severe hypertonia, fever, diaphoresis, and renal failure, attributed to “sepsis.” Oral baclofen was started for spasticity relief. On referral to our clinic several weeks later, evaluation revealed multilimb contractures with posturing of the limbs and trunk. Tendon reflexes were difficult to elicit, however, and H-reflexes were absent. Lumbar radiographs revealed an obvious catheter fracture at the spinal canal entrance. The revised catheter tip was located at approximately C2, and ITB dose started at 100␮g per 24 hours. About 36 hours after surgery, however, we noted fever, diaphoresis, and severe posturing with markedly elevated H-reflexes. Symptomatic relief ensued after lowering the catheter to C6 and increasing the dose rate to 200␮g per 24 hours. In summary, radiographic evidence of a broken ITB catheter requires surgical repair. However, a radiographically discontinuous lumbar catheter may still be capable of administering ITB into the neuraxis, as indicated by our initial electrophysiologic findings. Erroneous assumption of no flow through a broken catheter could precipitate severe ITB withdrawal symptoms if the postrevision dose rate is too low. Key Words: Baclofen; Rehabilitation. Poster 50 Developing a Measure to Appropriately Match Students With Disabilities and Assistive Technology Devices. Marcia Scherer (Institute for Matching Person and Technology, Webster, NY), Susan Zapf. Disclosure: Supported by the Center for Disease Control and Prevention (grant no. DD000219). Objectives: To develop and evaluate a process for measuring predisposition to the use of assistive technology (AT) for children and adolescents with disabilities enrolled in K through 12 schools; to map the measures to the International Classification of Functioning, Disability and Health for Children and Youth (ICF-CY); and to develop content for computerized scoring and interpretations and a CD training program for K through 12 educators. Design: National experts assisted in the development of the content of the materials. Educator, student, and parent feedback was obtained on the prototype materials. Setting: Professional experts in K through 12 education for students with disabilities throughout the U.S. region 4 schools (Houston, TX). Participants: 9 national experts, including the developer of the ICF-CY. 20 region 4 educators, students, and parents. Interventions: Not applicable. Main Outcome Measure: Designation of students according to predisposition to use AT so that device features and training for use can be matched to student needs and preferences. Content for scoring and interpretations and a CD training program. Results: The prototype process consists of 6 measures: (1) goal identification, (2) past support use, (3) technology experiences and usage, (4) activity performance and participation, (5) AT feature and student match, and (6) recommendations. Factor and cluster analyses revealed items that could be eliminated in order to condense the measures. National experts agreed that a scoring report with interpretations would be essential for K through 12 educators in documenting AT need. Content Arch Phys Med Rehabil Vol 89, October 2008