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24 Dorsal Laminectomy

in the Thoracolumbar Region

Cory Fisher and Andy Shores

Introduction be placed in the mid‐abdominal region to help elevate the area of
Dorsal laminectomy of the thoracolumbar region has been interest. Once positioned to the surgeon’s discretion, the animal is
described for treatment of intervertebral disc disease [1–17], frac- secured in this position using tape. A dorsal midline skin incision
tures [12–16], neoplastic processes [12–16,18,19], cysts causing is made for a distance of a minimum of two vertebrae cranial and
compression to spinal cord [20–22], and other disease processes caudal to the affected intervertebral disc space. The subcutaneous
that cause spinal cord compression [23,24]. Dorsal laminectomy is fat and fascia are incised using blunt/sharp dissection with
used to access dorsal, lateral and ventral aspects of the spinal canal Metzenbaum scissors until the deep lumbodorsal fascia is reached.
depending on the type of dorsal laminectomy appropriate to the A continuous scalloped incision is made bilaterally around each
disease process [13,14]. Numerous modifications to the dorsal spinous process in the superficial and deep external fasciae of the
laminectomy procedure have been described since Greene’s first trunk. Using periosteal elevators, the epaxial musculature is
report in 1951 [17]. Dorsal laminectomies are classified by the reflected laterally on both sides to the level of the accessory pro-
extent of the vertebrae removed. The four types of dorsal laminec- cess. Gelpi retractors are used to retract the epaxial musculature
tomies described in veterinary neurosurgery are (listed in order for better visualization of the dorsal and lateral aspect of the verte-
from the least amount of bone removed to the most) Funkquist B, bral column [12,13,19,26]. The spinous processes of the vertebrae
modified dorsal laminectomy, Funkquist A, and deep dorsal lami- cranial and caudal to the affected disc space are removed with bone
nectomy [13–15]. The two most commonly used are the Funkquist rongeurs [12–14,19]. A laminectomy is performed using a high‐
B and modified dorsal laminectomy [3]. An osteotomy of the speed surgical air drill [12–14,19]. Because the dorsal lamina is
spinous process instead of the traditional ostectomy has also been thinner than the lateral lamina, frequent pausing of the drilling is
reported [25]. Unilateral excision of the vertebral arch, including necessary to assess bone depth at the drilling site [3]. The outer
the articular processes (facetectomy), accessory process (fora- cortex of the lamina normally has a whitish tint. The medullary
menotomy) and pedicle (pediculectomy), have been performed bone is recognized by its reddish‐brown color. The inner cortex of
after osteotomy of the spinous process [25]. the lamina is very thin and also whitish in color [12–14,19]. Small
The type of dorsal laminectomy performed is based on the dis- Lempert or Kerrison ronguers are used to expand the laminectomy
ease process causing neurological dysfunction. Advanced diagnos- after entering the canal [3,13, 14]. The extent of bone removal is
tic imaging (myelography, CT, CT with myelography, or MRI) is dictated by the lesion of interest and amount of accessibility of the
used to determine the extent of the disease process. Once the extent vertebral canal needed (Funkquist A, Funkquist B, or modified
of the disease process is recognized and classified, the type of dorsal dorsal laminectomy).
laminectomy is chosen. After completing the decompression and the remainder of an
indicated procedure (tumor excision, opening of a subarachnoid
diverticulum, removal of scar tissue, etc.), the surgical site is thor-
Surgical Approach (Video 24.1) oughly lavaged with warm physiological saline and either gelatin
The patient is clipped and aseptically prepared for surgery then sponge or autogenous fat graft is placed over the laminectomy
positioned in sternal recumbency with the spinous processes site to prevent dural adhesions [3, 12]. Synthetic nonabsorbable
perpendicular to the surgery table. A rolled towel or sandbag may suture can then be used to span over the laminectomy site or the

Current Techniques in Canine and Feline Neurosurgery, First Edition. Edited by Andy Shores and Brigitte A. Brisson.
© 2017 John Wiley & Sons, Inc. Published 2017 by John Wiley & Sons, Inc.
Companion website: www.wiley.com/go/shores/neurosurgery

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