The Lumbodorsal Fascia as a Potential Source of Low Back Pain: A Narrative Review

Table 1

Histological studies exploring the potential nociceptive innervation of the posterior layer of the LF.

Study	Tissue source	Method	Nerve endings found	Remarks
Stilwell [26]	Macaca mulatta (), rabbit ()	Methylene blue	Rich supply by FNE. Groups of large Pacinian corpuscles at penetration points of dorsal rami through the fascia. Also small Pacinian-like and Golgi-Mazzoni	Study included human tissues too. However, no nerve type analysis was performed on those.
Hirsch [27]	Human ()	Methylene blue	FNE, “complex unencapsulated endings”.	Number of donors not mentioned.; Also found: unmyelinated nerve fiber network associated with blood vessels
Yahia et al. [28]	Human ()	IH: neurofilament protein and S-1 00 protein	FNE, Ruffini,
Bednar et al. [13]	Human (12),	IH: neuron-specific enolase	No terminal nerves	Study performed with CLBP patients only.; Found: small peripheral nerve bundles at the margins and in association with small vessels.
Corey et al. [29]	Rats (5)	3D reconstructions of thick (30–80 µm) tissue sections; IH: PGP 9.5, CGRP, fast blue	CGRP-positive FNE.	Also found: Some nonterminating CGRP-labeled fibers along blood vessels.
Tesarz et al. [30]	Rat () Human ()	IH: PGP 9.5, TH, CGRP, SP	Rich innervation with presumable nociceptive nerve endings (PG, CGRP).	Most nerve fibers located in the outer layer of the lumbar fascia and in the subcutaneous connective tissue.
Benetazzo et al. [31]	Human (2)	3D reconstruction of serial sections; IH: S100	Study did not investigate nerve terminations.	Small nerves (mean diameter 15 µm) found, flowing from the superficial sublayer into the adjacent subcutaneous loose connective tissue. No nerves visible in intermediate and deep sublayers.
Hoheisel et al. [15]	Rats (10)	IH: PGP 9.5, TH, CGRP, SP	Rich innervation with presumable nociceptive nerve endings (SP, CGRP).	Inflammation of the fascia induced an increase of presumably nociceptive fibers.
Barry et al. [14]	Mice (4–8)	IH: PGP 9.5, CGRP, SP.; Plus retrograde tracing.	Most nerve fibers contained CGRP	Two major subpopulations of neurons were found: those containing CGRP & SP and those containing CGRP but not SP.; Innervation density was 3x higher in the thoracolumbar fascia than in muscles of the back
Mense and Hoheisel [32]	Rats (5)	IH: PGP 9.5, TH, CGRP, SP, TRPV1	Rich innervation with presumable nociceptive nerve endings (SP, CGRP, and TRPV1).	Inflammation of the fascia induced an increase of presumably nociceptive fibers.

IH: immunohistochemical analysis. FNE: free nerve endings. PGP 9,5: a universal marker for neural structures. TH: marker for sympathetic neurons. CGRP: marker for presumably nociceptive fibers. SP: marker for clear nociceptive fibers (containing substance P). TRPV1: a novel marker for transient receptor potential receptor subtype V1 (one of the main receptor molecules in the membrane of nociceptors). of identification of termination of small nerves not mentioned. Not included in this table are studies on supraspinous, interspinous, or iliolumbar ligaments.