Nerve root enhancement of the cauda equina occurs in Guillain-Barré syndrome (GBS), but the frequency, diagnostic value, and meaning of this finding is unknown. We prospectively obtained gadolinium-enhanced lumbosacral spine MRIs in 24 consecutive patients with acute GBS and blindly rated nerve root enhancement as absent, mild, or prominent. The MRIs 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 "typical" GBS had enhancement, compared with 2 of 5 with a variant presentation. Sixty percent of patients with prominent enhancement had severe back or leg pain in contrast to 10% of patients with mild or no enhancement. The GBS disability grade (0 to 5 scale) was higher in patients with prominent enhancement, and significantly fewer patients with prominent nerve root enhancement could walk independently by 2 months. There was no relationship between nerve root enhancement and the timing of the MRI, CSF protein, any of several EMG abnormalities, duration of hospitalization, mean disability grade at 2 months, or the time required 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% sensitive of acute GBS and was present in 95% of typical cases. This finding may be useful when electrophysiologic abnormalities are equivocal. In addition, conspicuous nerve root enhancement correlates with pain, GBS disability grade, and duration of recovery.

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