PROSPECTIVE EVALUATION OF MRI LUMBOSACRAL NERVE ROOT ENHANCEMENT IN ACUTE GUILLAIN-BARRE-SYNDROME

Nerve root enhancement of the cauda equina occurs in Guillain-Barre sy ndrome (GBS), but the frequency, diagnostic value, and meaning of this finding is unknown. We prospectively obtained gadolinium-enhanced lum bosacral spine MRIs in 24 consecutive patients with acute GBS and blin dly rated nerve root enhancement as absent, mild, or prominent. The MR Is were obtained 13 days, mean, after onset of symptoms (range 2 to 42 days). Twenty of 24 patients had cauda equina nerve root-enhancement, which was mild in 6 and prominent in 14. Eighteen of 19 with ''typica l'' GBS had enhancement, compared with 2 of 5 with a variant presentat ion. Sixty percent of patients with prominent enhancement had severe b ack or leg pain in contrast to 10% of patients with mild or no enhance ment. The GBS disability grade (0 to 5 scale) was higher in patients w ith prominent enhancement, and significantly fewer patients with promi nent nerve root enhancement could walk independently by 2 months. Ther e was no relationship between nerve root-enhancement and the timing of the MRI, CSF protein, any of several EMG abnormalities, duration of h ospitalization, mean disability grade at 2 months, or the time require d for patients to improve to-grade 2. In two patients, the EMGs at 11 and 20 days, respectively, were normal except for slightly prolonged F -responses and neurogenic recruitment, but there were prominent nerve root enhancement and an elevated CSF protein. Enhancement of the cauda equina nerve roots with gadolinium on lumbosacral MRI is 83% sensitiv e of acute GBS and was present in 95% of typical cases. This finding m ay be useful when electrophysiologic abnormalities are equivocal. In a ddition, conspicuous nerve root enhancement correlates with pain, GBS disability grade, and duration of recovery.