Use of ‘‘inside-out’’ technique for direct visualization of a vacuum vertically unstable intervertebral disc during routine lumbar endoscopic transforaminal decompression—a correlative study of clinical outcomes and the prognostic value of lumbar radiographs
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Fecha
2019
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Publicado en
International journal of spine surgery, 2211-4599, Vol. 13, Nro. 5, 2019, p. 399-414
Publicado por
Elsevier
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Abstract
Background: The purpose of this study was to record the frequency of lumbar intervertebral disc vacuum
phenomenon on routine lumbar plain films taken prior to transforaminal endoscopic decompression surgery for
sciatica-type leg and back pain and to correlate it with visualized intradiscal pathology and clinical outcomes.
Methods: A prospective case series study of 200 consecutive patients with an average mean follow-up of 41.85
months who underwent lumbar endoscopic transforaminal decompression at 236 lumbar levels was conducted. The
sensitivity, specificity, and accuracy of vacuum phenomenon on preoperative x-ray to predict the presence of an empty
vacuum disc found during transforaminal microdiscectomy using the ‘‘inside-out’’ approach were calculated using the
YESSe technique. Clinical outcomes were assessed by both Macnab criteria and visual analog score (VAS) reduction.
Results: Of the 200 patients evaluated, 124 (62%) were deemed to have a vacuum disc on intraoperative probing
using the ‘‘inside-out’’ technique. During needle insertion the more severely degenerative discs are met with negative
pressures manifested by an air discogram. According to Macnab criteria, all patients who also had extruded disc
herniations had excellent results (8 of 200), with the mean VAS decreasing from 6.1 6 2.6 preoperatively to 1.9 6 1.4 at
the final follow-up (P , .01). This indicates a more severely degenerative disc causing nonspecific back pain due to lack
of anterior column support from the intervertebral disc, accentuating foraminal stenosis. Patients with contained disc
herniations (62 of 200) had excellent and good results 82.2% of the time. The mean VAS decreased from 6.9 6 1.7
preoperatively to 2.2 6 1.1 at final follow-up (P , .01). This identifies the disc as a contributing factor in low back
pain. It can also identify the disc and annulus in combination with foraminal stenosis as a contributing factor. In the
spinal stenosis group (130 of 200), 81.5% of patients had excellent to good results, and the mean VAS decreased from
6.3 6 1.5 preoperatively to 2.1 6 1.2 at final follow-up (P , .01). An analysis of lumbar x-ray vacuum phenomenon in
patients with visualized vacuum disc showed true-positive (35 patients) and false-negative (89 patients), compared with
an x-ray negative grading in patients without intraoperatively visualized vacuum disc of false-positive (2 patients); and
true-negative (74 patients); this allowed for calculation of sensitivity (28.2%), specificity (97.4%), and positive predictive
value (94.6%) of preoperative diagnostic x-ray in relation to intraoperatively visualized presence of the vacuum disc
during subsequent endoscopic decompression surgery. Direct endoscopic visualization of the inside of the vacuum disc
revealed longitudinal fissuring of the intervertebral disc as the most common finding in 77 of the 124 patients (62.1%)
with a vacuum disc. Cavitation with delamination was the second most common observation (21 patients). Fair
outcomes were associated with cavitation and delamination of the intervertebral disc from the endplates (P , .0001).
Conclusions: A vacuum phenomenon seen on lumbar x-rays is highly specific for a source of one component that
is actually a multiple source of nonspecific common back pain. A vacuum disc being found during ‘‘inside-out’’
transforaminal discectomy actually encompasses the disc, annulus, and foraminal stenosis as a multifactorial source of
nonspecific common back pain. Further studies of better prognosticators of failed endoscopic transforaminal
discectomy are required and are underway by the coauthors.
Palabras clave
Keywords
Disc vacuum phenomenon, Lumbar endoscopic transforaminal decompression
Temáticas
Radiografía
Informes de casos
Dolor de la región lumbar
Informes de casos
Dolor de la región lumbar