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Chapter 17: Ventral Cervical Decompression 159

canal of small dogs can lead to spinal cord compression, thus
removal of inner cortex with bone curettes is often safer in small‐
breed dogs. Bleeding from the cancellous bone may be controlled
with bone wax. It is recommended to open the vertebral canal along
the midline initially to avoid injury to the vertebral venous plexus.
Caution should be exercised when widening the slot to avoid injur-
ing the internal vertebral venous plexus, which can cause severe
hemorrhage. Removal of disc material can be achieved with blunt
curved nerve hooks, fine forceps, or a malleable iris spatula. All disc
material should be removed, exploring laterally, cranially and cau-
dally along the slot. After disc removal the spinal cord should be
visualized and should be sitting in normal position. Lateral inspec-
tion is very important to avoid leaving disc material that compresses
the nerve roots, which could lead to severe postoperative pain.
Injury to the vertebral venous plexus can occur at this stage and can
be controlled using gelatin sponge and by filling the surgical site
with cool sterile saline for a few minutes. After a final inspection
lavage is used to remove any debris and blood clots and surgical
closure is performed. It is unnecessary and contraindicated to place
any material in the slot site as it could interfere with bone fusion.
Fusion of the slot site is expected to occur 8–12 weeks postopera-
tively [5,6], although not all slot sites develop fusion [7]. Apposition
of the longus colli muscles is done with simple interrupted sutures.
The sternohyoideus muscle is apposed using a simple continuous
Figure 17.3 Ventral view of a ventral slot at C6–C7. The slot width and pattern. The subcutaneous tissues are closed in one or two layers
length should ideally be kept at about one‐third of the vertebral bodies. The with a simple continuous suture pattern, tacking to the fascia below
internal vertebral venous plexus is represented by the blue vessels running to reduce dead space and the risk of seroma. The skin is closed rou-
in the ventral aspect of the vertebral canal. Source: Reproduced with the tinely. A protective bandage can be applied over the skin incision.
permission of The Ohio State University.

Variations of Ventral Slot Procedure
Inverted Cone Technique
The technique of inverted cone is a modification of the traditional
ventral slot aiming at minimizing bone removal, and therefore
reducing the risk of vertebral subluxation [8]. The decompression
window resembles an inverted cone in which the base of the cone lies
adjacent to the ventral vertebral canal, allowing maximal surgical
access cranially, caudally and laterally (Figure 17.5). The width of the
ventral decompression window is limited to 20% of the cranial
vertebral body. This technique allows more complete removal of the
protruded disc from the vertebral canal, with less risk of hemorrhage
[8]. The inverted cone slot technique also minimizes collapse of
the disc space that could lead to postoperative nerve root entrapment
and lameness that may be seen with the traditional slot technique [9].

Slanted Ventral Slot Technique
A slanted slot technique has been described that removes only the
caudal aspect of the cranial vertebral body to access the extruded
disc material [10]. It is not a transdiscal procedure like the tradi-
tional ventral slot. Using a high‐speed round burr, a window is cre-
Figure 17.4 Transverse view of a ventral slot at C6–C7. The slot width ated cranial to the disc a few millimeters from the ventral tubercle.
should ideally be kept at about one‐third of the vertebral bodies to avoid A window in the bone is made to be approximately 20% of the
injuring the vertebral venous plexus (illustrated in blue, immediately ventral width and 20–25% of the length of the vertebral body toward the
to the nerve roots). Source: Reproduced with the permission of The Ohio vertebral endplate, aiming to enter the spinal canal at the level of the
State University. dorsal portion of the annulus fibrosus. The suggested advantage of
this procedure is that it provides access to the spinal canal at the site
cortex and dorsal longitudinal ligament are excised with a #11 of disc herniation without removing a large portion of the annulus
blade. Removal of the inner thin cortex can be achieved with bone fibrosus, presumably preserving more stability at the surgical site
curettes, Love–Kerrison rongeur, or Wayne laminectomy punch. than is preserved with the standard ventral slot. Because it is not a
Placing the footplate of the Love–Kerrison rongeur in the vertebral transdiscal slot, bone healing would probably occur more frequently.