Histologic Features of Needle-Nerve and Intraneural Injection Injury as Seen on Light Microscopy

Fig. 14.1

Typical histologic appearance of a rat peripheral nerve. (a) Connective tissue of the epineurium is unbalanced in terms of collagen richness, with partly altered tinctorial properties and areal-located adipocytes. The structures of the perineurium and nerve fibers are regular. (b) Detail of panel a. Typical laminar structure of the perineurium and a delicate fascicular architecture without lesions. Ad adipocyte, Ep epineurium, Fc fascicle, Pe perineurium. Hematoxylin and eosin (H&E) stain. Magnification: ×40 (a); ×100 (b)

Fig. 14.2

Typical histologic appearance of a rat peripheral nerve. (a) Magnified image with intact perineurium and axons. (b) Intraneural, extrafascicular application of 2 % lidocaine. Centrally located nerve fibers show no signs of degenerative changes. Schwann cell nuclei are prominent. Ax axon, Fc fascicle, Pe perineurium, Sc Schwann cell. H&E stain. Magnification: ×400 (a, b)

Fig. 14.3

Intraneural extrafascicular application of 0.75 % ropivacaine followed by pressure. (a) Epineurium infused with erythrocytes. The perineurium is preserved, as is the axonal structure intrafascicularly. (b) Detail of panel a. Ep epineurium, Er erythrocytes, Fc fascicle, Pe perineurium. H&E stain. Magnification: ×100 (a); ×400 (b)

Fig. 14.4

Intraneural intrafascicular application of saline. (a) Section of rat sciatic nerve composed of a single nerve fascicle. (b) Detail of panel a. Rupture of epineural connective tissue (arrow) is noted, with a loss of structural space intrafascicularly. Ep epineurium, Fc fascicle. H&E stain. Magnification: ×10 (a); ×40 (b)

Fig. 14.5

Intraneural intrafascicular application of H&E stain. (a) Visible injury to the epineurium and perineurium, probably corresponding to the site of needle penetration (thick arrow). Diffuse axonal injury is present. (b) Detail of panel a. Intraneural intrafascicular application of saline with high (>20 psi) injection pressure. Collagen fibers of epineurium are disintegrated, and there is extravasation of erythrocytes. The perineurium is ruptured. Axons show evidence of nerve injury, with increased interaxonal distances and edema. Ax axon, Ed edema, Ep epineurium, Er erythrocyte, Pe perineurium. Magnification: ×100 (a); ×250 (b)

Fig. 14.6

Intraneural intrafascicular application of 2 % lidocaine with high (>20 psi) injection pressure. (a) Rat sciatic nerve composed of two nerve fasciculi. (b) Detail of panel a. The epineurium is edematous, with infiltration of inflammatory elements and hyperemic blood vessels. The perineurium appears delaminated. Subperineural edema is present in the deeper area of the fasciculus. Bv blood vessels, Ed edema, Ep epineurium, Fc fascicle, Ic inflammatory cells, Pe perineurium. H&E stain. Magnification: ×10 (a); ×40 (b)

Only gold members can continue reading. Log In or Register to continue