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Percutaneous Endoscopic Discectomy for Extraforaminal ... - Index of

E94 Spine • Volume 32 • Number 2 • 2007

Figure 1. The difference between

the earlier transforaminal technique

and our extraforaminal technique

in terms of skin entry point

and the angle of needle insertion.

use percutaneous techniques for the treatment of spinal

disorders. 8–10 Yeung and Tsou have reported favorable

outcomes by applying transforaminal endoscopic discectomy

to a mixed group of 307 patients, out of whom 30

were extraforaminal/foraminal disc herniations. 9 Similarly,

Lew et al also reported their technique and results

for foraminal/extraforaminal disc herniations with

transforaminal endoscopic technique. 10 Both these techniques

essentially used an inside-out technique, meaning

thereby that the needle and working cannula are initially

positioned inside the disc, intradiscal decompression is

performed first, and subsequently the herniated foraminal/extraforaminal

fragment is removed.

The authors present a different technique, i.e., the

“targeted fragmentectomy” technique for endoscopic removal

of these extraforaminal disc herniations and also

evaluate the results in a series of 41 patients. The target

point for needle insertion is identified first from preoperative

images, and the needle track and starting point are

decided according to location of the hernia mass. The

skin entry point is relatively medial and the approach

angle is also relatively steeper in our technique as compared

with the earlier described techniques (Figure 1).

This gives a wider safety margin and makes the procedure

less painful and better tolerated by the patients. We

call it “extraforaminal targeted fragmentectomy” technique

because the main focus in our technique is on the

removal of the herniated disc fragment lying in the extraforaminal

territory first, with little, if any, removal of

the intradiscal contents. In some of the cases, we do advocate

removal of the intradiscal fragments lying inside

the posterolateral anulus, but such cases are few and the

indications are explained later in the text.

Materials and Methods

Between May 2001 and June 2004, 778 patients were operated

by a single surgeon (G.C.) for the diagnosis of a lumbar disc

herniation. Of them, 478 were operated by lumbar microdiscectomy

and 300 were operated by percutaneous endoscopic

lumbar discectomy technique using a working channel endoscope

(YESS System, Richard Wolff, Knittlingen, Germany).

Among the percutaneous group, 41 patients were with an extraforaminal

disc herniation. A retrospective analysis of these

41 patients along with a detailed description of our surgical

technique is the focus of the present study.

Patient selection criteria were as follows: 1) predominant

unilateral radiating leg pain with or without associated back

pain, 2) positive nerve root tension sign (sciatic or femoral

nerve), 3) corresponding imaging findings on CT and MRI

showing a single level soft extraforaminal disc herniation, and

4) failure of conservative treatment for 6 weeks. Patients who

were operated before 6 weeks had severe radicular pain and did

not show any signs of improvement during the first 2 weeks.

The exclusion criteria were as follows: 1) presence of intraspinal

pathology correlating with clinical symptoms, 2) associated

evidence of bony foraminal or central stenosis with

facet hypertrophy, 3) presence of instability, and 4) calcified

disc.

In the preoperative assessment, the patients were evaluated

for their pain on a Visual Analog Scale (VAS) and functional

assessment by a patient-based questionnaire (Oswestry Disability

Index [ODI]). Clinical examination was performed for

any nerve root tension sign and neurologic deficit. Routine

lumbar radiographs along with CT scan and MRI scan were

taken to outline the exact nature and level of the pathology

(Figures 2, 3A). CT and MRI images were also used to calculate

the exact point of skin entry for the needle insertion. VAS

Figure 2. Preoperative MR sagittal view of the far lateral region

with an up-migrated sequestrated herniated fragment (arrow) arising

from L5–S1 disc, compressing the nerve root.

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