Selective nerve root blocks for the treatment of sciatica: evaluation of injection site and effectiveness--a study with patients and cadavers.
OBJECTIVE
To relate different types of radiographic contrast material distributions to anatomic compartments by using cadaveric specimens and to relate the injection site to treatment-induced discomfort and therapeutic effect.


METHODS
The contrast material distributions of selective nerve root blocks (SNRBs) in 36 patients (13 women, 23 men; mean age, 52 years; age range, 22-88 years) were graded by two radiologists in conference as type 1 (tubular appearance), type 2 (nerve root visible as filling defect), or type 3 (nerve root not visible). These patterns were correlated with pain reduction after 15 minutes and 2 weeks (with a visual analogue scale of 100-mm length). In addition, 30 nerve roots were injected with iodine-containing contrast material and blue dye in three cadaveric specimens. Radiographs were compared with anatomic sections.


RESULTS
After 15 minutes and 2 weeks, 75% and 86% of the patients, respectively, reported pain relief. Mean pain relief length after 15 minutes for type 1 distribution was 60 mm; for type 2, 44 mm; and for type 3, 22 mm; and after 2 weeks, it was 34 mm for type 1, 31 mm for type 2, and 57 mm for type 3. There was no correlation between early and late response. Pain during intervention was less pronounced in type 2 injection, compared with type 1 (P = .002). On the basis of anatomic sections, type 1 injection was intraepineural; type 2, extraepineural; and type 3, paraneural.


CONCLUSIONS
Therapeutic SNRB is effective in sciatica, but early response does not predict the effect after 2 weeks. Type 1 injections are more painful than type 2 injections.
Pfirrmann
C W
CW
Department of Radiology, University Hospital Balgrist, Forchstrasse 340, CH-8008 Zurich, Switzerland. christian@pfirrmann.ch
Oberholzer
P A
PA
Zanetti
M
M
Boos
N
N
Trudell
D J
DJ
Resnick
D
D
Hodler
J
J
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000577:Amides / Q000008:administration & dosage; D000779:Anesthetics, Local / Q000008:administration & dosage; D000893:Anti-Inflammatory Agents / Q000008:administration & dosage; D003287:Contrast Media / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D007267:Injections / Q000379:methods; D007479:Iopamidol / Q000008:administration & dosage; D008297:Male; D008875:Middle Aged; D009407:Nerve Block; D010147:Pain Measurement; D011859:Radiography; D000077212:Ropivacaine; D012585:Sciatica / Q000000981:diagnostic imaging / Q000628:therapy*; D013126:Spinal Nerve Roots / Q000000981:diagnostic imaging; D014222:Triamcinolone Acetonide / Q000008:administration & dosage
D000577:Amides; D000779:Anesthetics, Local; D000893:Anti-Inflammatory Agents; D003287:Contrast Media; D000077212:Ropivacaine; D014222:Triamcinolone Acetonide; D007479:Iopamidol