The Transforaminal Endoscopic Lumbar Decompression and Foraminoplasty Procedure
Transforaminal Endoscopic Lumbar Decompression and Foraminoplast (ELDF) technique is performed under aware-state analgesia with the patient in the prone position on a humpback radiolucent table extension. It consists of two phases Spinal Probing and Discography and Endoscopic Foraminoplasty and Decompression.
Spinal Probing and Discography Procedure. (Phase 1)
Under X-ray guidance, a spinal probing cannula (Arthro Kinetics Plc) is inserted into the spinal foramen via a posterolateral approach (not directly from behind the back) facilitated by the use of a specially designed X-ray alignment jig. The distribution of evoked sensations and the degree to which they reproduce the patient’s predominant presenting symptoms is recorded on a data sheet by a trained observer during probing of the paravertebral musculature, the lateral facet joint surface, the anterior facet joint margin, the anterior facet joint–annular interval and the annular (disc) wall. Radio-opaque dye (Omnipaque® 240 [Nycomed Ltd, Romsey, Hampshire, England]) is then injected into the intervertebral disc to evaluate its integrity. The pattern of dye distribution, acceptance volume and leakage are recorded, together with pain reproduction during discography pressurization.
Evoked sensations that reproduced the patient’s predominant presenting symptoms are classed as ‘concordant’ symptoms. Patients in whom spinal probing and discography demonstrated concordant symptoms proceeded to ELDF at the level evidencing the most concordant symptom reproduction. Where symptoms are dyscordant (similar but not identical to the predominant presenting symptoms) or overlapping symptoms arising at more than one spinal level passed through the stepping stone evaluation of Differential Spinal Probing and Discography . In this steroid (80mg Depomedrone) is inserted at the most responsive level and anaesthetic (2ms of 0.5% Naropine) is inserted at the adjacent level. The temporal modification of individual symptoms determines the source of the pain and the site for subsequent ELDF.
Endoscopic Lumbar Decompression and Foraminoplasty Procedure. (Phase 2).
Using the Arthro Kinetics Plc system, the needle used to perform discography down the spinal probing cannula is replaced with a long guide wire. The endoscope dilator and cannula are railroaded down the guide wire to the foramen under X-ray control. The dilator is removed and the endoscope is inserted to offer visualisation of the foraminal contents. A side-fire irrigated laser probe (Lisa Laser Gmbh) is inserted through the endoscope’s working channel. The laser is used to define the margins of the foramen and to commence foraminotomy (widening of the foramen). Rather than initiating this with reamers when the nerve could be harmed, the tissues adjacent to the nerve in the Safe Working Zone between the exiting nerve and the dura are progressively removed until the nerve can be mobilised and the endoscope cannula inserted securely and safely. The Superior Foraminal Ligament running from the apex of the superior or ascending facet joint to the base ot the transverse process is defined and removed. The facet joint marginal and apical osteophytes and vertebral shoulder and rim osteophytes are removed together with perineural scarring from the Dorsal Root Ganglion to the inferior pedicle. The nerve is mobilised with a nerve root retractor until free of tethering anteriorly to the disc and vertebrae and through out its passage through the foramen. The foramen is enlarged with trephines, powered reamers and manual burrs until clear access to the epidural space is achieved. Where indicated protruding disc is removed with care to avoid exposing intervertebral graft or cages in cases of Failed Back Surgery, Failed Fusion Surgery or Failed Total Disc Replacement. Where there is a simple disc protrusion, extrusion or sequestrum or radial tear, the disc material is stained with indigo-carmine dye. This is taken up preferentially by degenerate disc material. During the discectomy phase only the darkly staining degenerate disc material is removed. We try to remove only degenerate disc material. Whilst previously great efforts were made to insert the endoscope in to the disc to facilitate a wide extirpation of disc material through a 5mm entry portal, we now limit access to a 3.5mm portal where possible removing less than a gram of material thus performing a limited herniectomy of the disc material.
The laser is inserted to use laser energy to shrink the weak bulging disc wall in a process called Annuloplasty. Where the annulus is quiescent and good mobilisation of the nerve has been achieved then entry in to the disc and disturbance of these already degenerate materials will be avoided where possible.
After the nerve has been mobilised, it is returned to its correct pathway because it has usually been drawn medially by the foraminal scarring.
After insertion of Depomedrone 80mg and Gentamycin 80mg in the operation zone, the wound is closed with a single suture.
Post-operative Stage.
Patients are discharged the day of, or morning following, surgery. A muscle balance physiotherapy staged regime is re-commenced on the first day following surgery, amplified with neural mobilization drills and continued on a monitored self-help basis for 3 months. Patients are reviewed at 6 and 12 weeks unless clinical symptoms required closer supervision and subsequently according to any study protocol.
