Magnetic resonance imaging anatomy and morphometry of lumbar intervertebral foramina to guide safe transforaminal subarachnoid punctures

Abstract

Percutaneous transforaminal lumbar punctures (TFLPs) offer alternative access routes to the lumbar subarachnoid cistern. Safe fluoroscopic insertion of a needle through a lumbar intervertebral foramen (IVF) should ideally avoid the exiting spinal nerve and surrounding vascular pedicles. A crescentic region in the posterior aspect of IVF is the conventional position for needle placement during TFLP, but the underlying anatomic basis for this has not been evaluated fully. To enhance TFLP safety, we defined the morphometry of normal lumbar IVFs and precise locations of neurovascular structures in the IVF posterior crescent. We retrospectively reviewed high‐resolution T2‐weighted lumbar spine magnetic resonance images of 40 normal adults to establish normative dimensions of each IVF from L1 to L5 bilaterally. We segmented the IVF posterior crescent into three parts, and within each, measured the areas occupied by neurovascular structures. We statistically correlated the presence or absence of neurovascular structures in each crescent segment using a chi‐square test. The mean morphometrics for all 304 IVFs in 10 males and 30 females of similar ages were: area 115.3 ± 29.5 mm2; height 18.0 ± 2.4 mm; and width at mid‐disc level 5.6 ± 2.1 mm. We found a significant association between crescent segment and presence or absence of neurovascular structures (χ2 = 95.9, p < .001). A post‐hoc calculation of adjusted standardized residuals identified a significant association between the middle crescent segment and absence of neurovascular structures. Thus, the middle segment of the IVF posterior crescent is significantly most devoid of neurovascular structures, and more often would be the safest target for needle placement during TFLP.

Analysis of Influencing Factors on Short-Term Efficacy of Percutaneous Transforaminal Endoscopic Lumbar Discectomy in the Treatment of Lumbar Disc Herniation

“…According to the clinical study, the effective rate of treatment is about 80 %, which far exceeds that of previous treatment methods. After percutaneous transforaminal endoscopic lumbar discectomy treatment, the recovery time of patients is short due to their small trauma [7] . After surgery, the adhesion of nerve root and dural sac is the result of the combination of local injury, hematoma formation and inflammatory reaction.…”

The Spatial Characteristics of Intervertebral Foramina within the L4/L5 and L5/S1 Motor Segments of the Spine

“…There is a lack of comprehensive research that addresses this issue in a holistic way. The topic of the dimensions of the intervertebral foramen appeared in the studies of Khalaf et al [18]. The authors assessed the surface area, vertical, and horizontal dimensions of the intervertebral foramen.…”

A novel anatomo-physiologic high-grade spondylolisthesis model to evaluate L5 nerve stretch injury after spondylolisthesis reduction

“…The incidence of neurological deficits, such as nerve root, cauda equina, and peripheral nerve palsy, has been reported as high as 45%, although 90% of cases eventually improve upon follow-up [5,10,16,21]. Besides traction injury to the L5 nerve root during the reduction process, other possible mechanisms of L5 palsy include neurovascular dysfunction, foraminal morphometry, temporary displacement of the L5 nerve root during decompression, and hyperextension of the patient during positioning [4,9,11,19,21]. In order to minimize postoperative L5 nerve palsy after reduction of high-grade spondylolisthesis, several authors hypothesize that most of the total L5 nerve strain occurs during the second half of reduction, and therefore suggest a reduction of no more than 50% and/or decompression of the L5 nerve roots prior to reduction [10,13,20].…”