Journal international de médecine physique et de réadaptation
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Improvement of Motor, Sensory, and Functional Status of Post-Guillain-Barre Syndrome with the Use of 4-Aminopyridine

Jay M. Meythaler and Robert C. Brunner

Objective: To determine the safety and efficacy of orally delivered 4-aminopyridine for motor weakness due to Guillain-Barre Syndrome (GBS) under a FDA approved protocol (IND No: 58,029). Setting: Tertiary care outpatient and inpatient rehabilitation center directly attached to a university hospital. Subjects: Seven subjects who were unable to ambulate more than 200 feet without assistive devices and had residual nonprogressive motor weakness due to GBS more than one year out from the initial episode. Design: Subjects were randomized to a double-blind, placebo-controlled, cross-over design, which had two fourweek treatment arms with a one-week washout. The average dosage at 4 weeks was 30 milligrams (mg) per day. Data set: Data for motor strength utilizing a traditional 5 point motor scale and handgrip strength were evaluated. Differences over times were assessed via descriptive statistics, Friedman’s analysis, Wilcoxon signed-rank, ANOVA and paired Student’s t-test. Subjects were evaluated for dose and side effects as required by our FDA approved protocol (IND No: 58,029). Results: During four weeks of treatment, the averaged lower extremity (LE) motor strength increased from 3.2 SD ± 1.2 to 3.7 SD ± 1.0 (p<0.0001), the average upper extremity (UE) motor strength increased from 3.2 SD ± 1.2 to a maximum of 4.3 SD ± 0.9 (p=0.0073) and the grip strength bilaterally increased from 8.2 lbs. SD+ 9.1 lbs. to 12.2 lbs. SD ± 9.1 lbs. (p=0.0243). There were no statistical changes in the placebo arm regarding LE and UE motor strength or the grip strength at week 4 (p>0.05). Only three laboratory tests had a statistically significant change as the uric acid changed from 6.4 to 6.5, the SGOT went up from 25.1 to 27.9 and the hematocrit dropped from 42.7 to 41.6. None of these results were deemed to be clinically relevant changes. There were no seizures and there was no significant change in the Q – T interval in any of the subjects. Three subjects did report increased paresthesias on 4-aminopyridine. Conclusion: This Phase IIa trial indicates 4-aminopyridine was generally safe and may be effective in improving the motor function of GBS subjects. Further research requires delineating its biologic half-life, which appears to be longer than two weeks.