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					                         2001 ASNR Annual Meeting Abstracts
Clinical Significance of "Endplate Extravasation"
during Percutaneous Vertebroplasty
Patel, G. M. * Schweickert, P. A. * Jensen, M. E. * Marx, W. F. * Kim, A. * Kallmes,
D. F.
University of Virginia, Charlottesville, VA

To determine the clinical relevance of extravasation of methylmethacrylate through endplate
fractures, into the adjacent disk spaces, during transpedicular vertebroplasty.

Materials & Methods
A retrospective chart review was made to identify vertebroplasty procedures in which barium-
opacified methylmethacrylate was noted to traverse the superior or inferior endplate to reside in
the adjacent disk space. The amount of cement residing in the disk space following the procedure
was subjectively described as "small" or "large." The clinical outcomes of these cases were
assessed based on change in severity of pain, medication requirement, and activity level, and on
the incidence of subsequent fracture at adjacent vertebral body level. Pain severity, medication
requirement, and activity level were catalogued using semiquantitative scales. A separate group
of patients where no extravasation was noted during vertebroplasty constituted the control group.
Clinical outcome for the various outcome parameters were compared between cohorts either
using chi square or one-way unstacked ANOVA.

Twenty-four patients were identified who had extravasation of methylmethacrylate into adjacent
disk spaces during vertebroplasty. Twenty-three (96%) of these cases demonstrated "small"
amounts of methylmethacrylate in the disk space, while 1 (4%) demonstrated a large amount of
methylmethacrylate in the disk space. Positive clinical result based on pain relief, defined as >/=
3 point decrease of pain on a 10 point scale, was seen in 23 (96%) of the "endplate extravasation"
patients as compared to 19 (90%) of control patients (p = 0.47, chi square). Mean decrease in
pain severity was 7.21 ± 2.5 vs 6.23 ± 3.07 for the "endplate extravasation" vs control groups,
respectively (p = 0.49, one-way ANOVA). A strong trend toward greater improvement in
activity level was seen in the "endplate extravasation" group as compared to controls (p = 0.074,
one-way ANOVA). The single case of "large" amount of extravasation suffered a fracture of the
adjacent vertebral body within several days following vertebroplasty.

Small amounts of extravasation of methylmethacrylate through endplates into adjacent disk
spaces may represent a favorable prognostic sign for positive clinical outcome after percutaneous
vertebroplasty. We conjecture that "endplate extravasation" indicates presence of a persistent
fracture line that is subsequently reinforced by methylmethacrylate.

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