FUTURE AMBULATION PROGNOSIS AS PREDICTED BY SOMATOSENSORY-EVOKED POTENTIALS IN MOTOR COMPLETE AND INCOMPLETE QUADRIPLEGIA

Objective: The purpose of this prospective study was to determine the efficacy of tibial somatosensory evoked potentials (SEPs) in predictin g ambulation in tetraplegic individuals. Design: This was a prospectiv e study of a cohort of cervical spinal cord-injured patients who had S EPs recorded within 72 hours to 2 weeks post-SCI and whose ambulation outcome was followed up to 2 years post-SCI. Setting: Regional Spinal Cord Injury (SCI) Center. Patients: All male and female subjects admit ted to the center from 1988 to 1991 between the ages of 15 and 60 year s who demonstrated C-4 through T-1 complete and incomplete acute SCIs were asked to participate in this study. Measurements: The tibial nerv e cortical SEPs were graded as either present or absent. The waveforms were also graded as less than 0.5 mu V or greater than or equal to 0. 5 mu V. Quadriceps strength plus touch and pin sensation were tested w ithin 72 hours to 2 weeks post-SCI. Ambulation was rated as absent, ex ercise, household, or community. The ambulatory and clinical status we re assessed monthly for 3 months, and then at 6, 12, 18, and 24 months post-SCI. Statistical analysis using the two-tailed Fisher's exact te st was performed relating the initial clinical and SEP data to ambulat ion outcome up to 24 months post-SCI. Results: All 13 subjects with a right and/or left quadriceps manual muscle test (MMT) greater than 0/5 became ambulatory. Of the 9 subjects with an initial bilateral quadri ceps MMT = 0/5, only 1 recovered enough lower limb function to ambulat e (p = .0001). One of the 7 subjects with absent touch sensation in th e lower limbs became ambulatory, whereas 14 of the 15 subjects with to uch sensation present became ambulatory (p = .002). All 7 subjects wit h absent pin sensation in the lower limbs were nonambulatory, and 14 o f 15 subjects with pin sensation present became ambulatory (p < .0001) . Of the 9 subjects with bilaterally absent cortical SEP waveforms, 2 became ambulatory. Twelve of the 13 subjects with a cortical SEP wave present became ambulatory (p = .0015). Of the 10 subjects with a corti cal SEP wave amplitude less than 0.5 mu V, only two became ambulatory, whereas all 12 subjects with an amplitude greater than or equal to 0. 5 mu V became ambulatory (p = .00014). In no subject did the SEP predi ct future ambulation where the clinical examination did not also predi ct recovery of ambulation. Conclusion: Both the early postinjury clini cal evaluation and the SEP predicted ambulation outcome to a significa nt degree, but the SEP offered no additional prognostic accuracy over that provided by the clinical examination. (C) 1995 by the American Co ngress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation