A Literature Review of Dorsal Root Entry Zone Complex (DREZC) Lesions: Integration of Translational Data for an Evolution to More Accurate Nomenclature

Abstract

The purpose of this translational review was to provide evidence to support the natural evolution of the nomenclature of neuromodulatory and neuroablative radiofrequency lesions for pain management from lesions of individualized components of the linear dorsal afferent pathway to "Dorsal Root Entry Zone Complex (DREZC) lesions." Literature review was performed to collate anatomic and procedural data and correlate these data to clinical outcomes. There is ample evidence that the individual components of the DREZC (the dorsal rami and its branches, the dorsal root ganglia, the dorsal rootlets, and the dorsal root entry zone) vary dramatically between vertebral levels and individual patients. Procedurally, fluoroscopy, the most commonly utilized technology is a 2-dimensional x-ray-based technology without the ability to accurately locate any one component of the DREZC dorsal afferent pathway, which results in clinical inaccuracies when naming each lesion. Despite the inherent anatomic variability and these procedural limitations, the expected poor clinical outcomes that might follow such nomenclature inaccuracies have not been shown to be prominent, likely because these are all lesions of the same anatomically linear sensory pathway, the DREZC, whereby a lesion in any one part of the pathway would be expected to interrupt sensory transmission of pain to all subsequent more proximal segments. Given that the common clinically available tools (fluoroscopy) are inaccurate to localize each component of the DREZC, it would be inappropriate to continue to erroneously refer to these lesions as lesions of individual components, when the more accurate "DREZC lesions" designation can be utilized. Hence, to avoid inaccuracies in nomenclature and until more accurate imaging technology is commonly utilized, the evidence herein supports the proposed change to this more sensitive and inclusive nomenclature, "DREZC lesions."

Keywords: DREZ; chronic pain; ganglia; pulsed radiofrequency treatment; radiofrequency ablation; spinal.

Figure 1

Schematic of variability of dorsal root entry zone complex (DREZC) anatomy in correlation to typical radiofrequency cannula anatomic position. 1. Lumbar vertebra with spinal cord and sensory afferent pathway segments with magnified and labeled view box to the right side. The dorsal root entry zone complex (DREZC) is composed of components labelled A, C, E, and F. A. Dorsal Root Entry Zone (DREZ). B. Radiofrequency (RF) cannula in typical position, adjacent to the DREZC. C. Dorsal Rootlets (DRL). Herein artistically depicted as one line, but DRL can vary in number to as many as 15 DRL per DREZC. D. The anatomic distribution of the energy wave emitted by the RF cannula. E. Dorsal Root Ganglion (DRG). F. Dorsal root (DR). G. Ventral root. H. Medial branch. I. Intermediate branch. J. Lateral branch. 2–5 show variability in anatomic position and number of DRG relative to the vertebra and RF cannula. Arrow depicts DRG. 2. Intraforaminal DRG anatomy. 3. Intraspinal DRG anatomy. 4. Extraforaminal DRG anatomy. 5. DRG Bigangliar anatomy.

Figure 2

DRG-foraminal anatomy from L1 through S4 spinal levels.

Figure 3

DRG-foraminal anatomy from C6 through T12 spinal levels.

Figure 4

Fluoroscopic image of a radiofrequency needle placement and wire insertion for neurosensory stimulation prior to neuromodulatory pulsed radiofrequency right L5 DREZC lesion. (A) Posteroanterior fluoroscopic view. (B) Right oblique fluoroscopic view – 25°. Deidentified mage obtained from Dr. Visnjevac with documented patient consent.

Figure 5

Pulsed radiofrequency DREZC lesion success and failure rates to achieve adequate analgesia per indication. Extrapolated from, Facchini G, Spinnato P, Guglielmi G, Albisinni U, Bazzocchi A. A comprehensive review of pulsed radiofrequency in the treatment of pain associated with different spinal conditions. Br J Radiol 2017; 90: 20,150,406.9

Figure 6

Surgical DREZ RF lesion success and failure rates to achieve adequate analgesia per indication.