The Fundamental Open Surgical Method

The Fundamental Open Surgical Method



Abstract


Considerable experience in open techniques is necessary before the PDLS surgeon can learn the nuances of pathological anatomy and its appropriate operative therapy. However, if certain technical fundamentals are appreciated, this experience will be rendered efficiently and safely.


The most common procedure for the PDLS surgeon is unilateral root decompression. A step-by-step routine for this exposure (as described) is important, though an uncompromising allegiance to it is not recommended. This technique can be expanded to gain visual and manual access for decompression of the contralateral side, with preservation of the laminae. When foraminal or extra-foraminal root decompression is needed, this can be done with or without preservation of the pars.


The (total) hemilaminectomy from caudal to cephalad is a safe and versatile technique when unilateral root compression pathology is complex. It also can be expanded medially to allow contralateral decompression in selected patients.


In severe cases of severe and multilevel stenosis, complete laminectomy is usually the safest and most effective technique. The “en bloc” laminectomy technique has been developed and allows the surgeon a margin of safety from dural disruption beyond that of the common piecemeal laminectomy.


Root decompression in operated anatomy can present a challenge. With cicatrix present, the surgeon must always effect the necessary exposure at the lateral margin of the spinal canal (medial to the facets). Decompression of any residual compression must proceed lateral to medial.


Placement of pedicle screws for arthrodesis requires precise fluoroscopic guidance as there is individual variance of pedicle entry vis-a-vis landmarks. Iliac fixation is rarely necessary in PDLS surgery; the S2 alar technique has some advantages over that of the more common iliac screws fixation.


Keywords: en bloc laminectomy, U-turn technique, parsectomy, extra-foraminal, lateral corridor, S2 alar iliac screw, shoestring dural closure



One thing alone not even God can do, to make undone whatever hath been done.


Aristotle



We are what we repeatedly do. Excellence, then, is not an act, but a habit.


Aristotle


6.1 Introduction


Although the pathophysiologic processes in surgical PDLS are few, the individual pathological anatomy is multiplex. For instance, magnetic resonance imaging (MRI) depiction of a herniated lumbar disc may be unequivocal, and yet the surgeon will not gain from its review other important specifics to be determined only by direct operative visualization. Is the herniation contained, or partially or completely extruded? Is the posterior longitudinal ligament attenuated or is it essentially intact with a small defect? Has there been significant annular disruption? Is there herniated disc in the root axilla? Is there potential for residual interspace disc to extrude? And if pathology is recurrent with previous surgery, the surgeon cannot anticipate from the MRI the precise extent of the cicatrix, adhesions, and dural thinning. Furthermore, anomalous root pathology is not infrequent and usually is unappreciated on the MRI.


Such information can be crucial to the success of the surgery on a short- and long-term basis. Open operative techniques allow for maximal intraoperative assessment and instrument manipulation. Minimally invasive surgery on the PDLS has wide acceptance. However, its application requires a surgeon who is experienced in open techniques. Without such experience, the nuances of anatomy and pathology cannot be learned effectively.


Thus, the open methods described in this chapter will give the young surgeon the safest and most educational experience in the operating room. They are applicable to the full gamut of PDLS pathology.


6.2 Surgical Decision-Making Processes


6.2.1 Patient–Surgeon Interaction in Surgical Decision-Making




  • Degenerative lumbar spine surgery (99%) is for subjective symptom (pain) relief and thus the patient must have significant input into surgical decision-making.



  • With rare exception, no patient “needs” surgery to prevent significant neurological compromise (exceptions are patients with: a cauda equina syndrome; painful progressive foot-drop; painful progressive quadriceps weakness).



  • If pain symptomatology is improving, then surgical decision should be deferred.



  • If the patient decides he/she “can live with the pain,” this is not to be discouraged.



  • Risks of surgery, including those from comorbidities, should be clearly explained and documented.



  • Follow-up evaluation may be necessary before the surgeon (and the patient) can make the appropriate decision.


6.2.2 Operative Plan with Radicular Pain Presentation




  • Surgeon’s mission: as limited decompression as possible.



  • Identification of image pathology consistent with radicular pain syndrome.



  • Indistinct correlation between clinically symptomatic root(s) and image may require extension of decompression.



  • Prophylactic decompression for asymptomatic image pathology, while addressing the symptomatic level, is decided on an individual basis.



  • No attention to correction of deformity unless relevant to root decompression—actually or potentially.



  • Instrumentation avoided without clear indication.


6.2.3 Operative Plan with Primary Axial Lumbar Pain




  • Operative treatment remains controversial.



  • Compression-loading chronic axial lumbar pain (CALPcl) from disc prolapse or posterior subligamentous herniation) may rarely require limited discectomy.



  • In the setting of high-grade anti-gravity chronic axial lumbar pain (CALPag), best surgical candidate is with severe degenerative discogenic/interspace changes (with bone edema) on MRI (with/without listhesis) at a single level.



  • Positive disc-block response would provide further weight to selective process. If a repeat of a negative disc-block remains unchanged, then surgery is not indicated.



  • Dynamic standing flexion-extension X-rays should be evaluated for abnormal motion (especially hyperrotation) at levels that appear normal on MRI.



  • Therapeutic arthrodesis at painful level at discretion of surgeon (bony arthrodesis with/without various instrumentation options is most common); nonbony “dynamic” arthrodesis can provide a clinically effective stability.



  • Reduction of listhesis at painful level may be detrimental in terms of hardware stress and effect on sagittal alignment.



  • Multilevel degenerative changes on MRI are problematic for determining painful level and/or for increased potential of developing symptomatic adjacent segment disease; the resulting long-term risk–return ratio is thus negatively affected.


6.3 Fundamentals


6.3.1 Opening and Closure of Surgical Incision




  • The length of the skin incision is only relevant if it is too small and thus hindering visualization and/or manipulation of instruments.



  • The deep fascia is cleared bilaterally to allow for layered anatomic closure.



  • At closure, meticulous attention to epidural and muscular wall hemostasis will obviate the need for a drain in most cases.



  • Closure of the fascia is done with interrupted sutures. For easier anatomic closure, it is recommended that all fascial sutures be placed before tying them down.



  • Optional attachment of fascia to spinous process (SP; ▶ Fig. 6.1).



  • Closure of subcutaneous adipose tissue adds some element of strength resisting wound dehiscence, especially in obese patients.



  • Superficial subcutaneous closure (inverted absorbable suture) of the dermis is imperative in establishing an adequate well-apposed skin closure.



  • Any drainage catheter should exit cephalad to incision, away from fecal contamination.



    Fig. 6.1 Augering spinous process with towel clip for anatomic closure of deep fascia.


    9781626238077_c006_f001.TIF



6.3.2 Decompression with Nonoperated Anatomy




  • The ligamentum flavum is preserved as much as possible during primary bone removal, thus serving as a barrier of safety preventing durotomy.



  • The ligamentum flavum is always removed by detaching it laterally (with Kerrison rongeurs) beginning at either its upper (cephalad) or lower (caudal) edge. It will thus be separated from underlying dura in a lateral-to-medial fashion. Complete removal requires its medial incision (near midline) before or after lateral detachment.



  • Early nerve root visualization is done, whenever possible, before attention to its compressive pathology. With intracanalicular pathology, this visualization is almost always distal to the pathology (i.e., foraminal entrance).


6.4 Unilateral Decompression of Nerve Root with Nonoperated Anatomy: The “U-Turn” Technique


This is the fundamental root decompression technique for common pathologies with normal (nonoperated) anatomy.


6.4.1 Clinical Presentation




  • Unilateral congruent monoradiculopathy (discogenic or stenotic).


6.4.2 Image Pathology




  • Herniated lumbar disc.



  • Subarticular (lateral recess) stenosis on symptomatic side.



  • Small/moderate synovial cyst.


6.4.3 Contraindication




  • Moderate/severe central stenosis (with thick hypertrophic ligamentum flavum).



  • Large synovial cyst extending to midline.


6.4.4 Operative Procedure


(After surgeon’s preference for positioning, skin prep, localization.)




  1. Incision through deep fascia with cautery to expose SP and lamina of cephalad (superior) and caudal (inferior) vertebrae.



  2. Subperiosteal dissection with cautery laterally from lamina along medial inferior articular process (IAP) of superior vertebra to drop-off into medial facet space.



  3. Clearance of lamina and medial pars of inferior vertebra.



  4. Begin partial hemilaminectomy of superior lamina by rongeuring (Leksell) its lower edge.



  5. Drilling to expand partial hemilaminectomy and extending laterally along medial aspect of IAP (approximately 3 mm).



  6. Completion of partial hemilaminectomy to upper edge of ligamentum flavum with Kerrison rongeurs confirmed by visualization of dura and/or epidural adipose tissue (▶ Fig. 6.2).



  7. Extension of bone removal with Kerrison rongeurs laterally along medial aspect of IAP external to ligamentum flavum and extending to facet.



  8. Grasping superficial leaf of ligamentum flavum and its removal from medial facet and inferior laminal attachment, with visualization of deep leaf attachment under cephalad edge of inferior lamina.



  9. Beginning U-turn epidural decompression by lifting medial/superior edge of ligamentum flavum (under superior lamina) with nerve hook and inserting underneath a 1- or 2-mm Kerrison for its incision medially/caudally to inferior lamina (▶ Fig. 6.3).



  10. With 2- or 3-mm Kerrison, advancing laterally (footplate heel medial) removing upper edge of inferior lamina to pars, and visualization of root at entrance to foramen (distal to pathology) (▶ Fig. 6.4).



  11. Continuing cephalad grasping ligamentum flavum laterally until complete removal. (Important: if root has not been visualized, then the surgeon may be distal to foraminal exit of root and thus must be careful advancing cephalad until root anatomy established.) (▶ Fig. 6.5).


    (Note: The surgeon may elect to remove ligament from cephalad lateral edge caudally, when pathology is nonadherent to dorsal aspect of root: cicatrix, synovial cyst.)



  12. Follow-up extension of foraminotomy and further lateral decompression as necessary using drill/Kerrison.



    Fig. 6.2 Extension of hemilaminectomy to above attachment of ligamentum flavum.


    9781626238077_c006_f002.TIF



    Fig. 6.3 Elevation of superior edge of ligamentum flavum to gain access to epidural space to begin medial arm of U-turn, with extension of ligamentum incision caudally to under lamina edge.


    9781626238077_c006_f003.tif



    Fig. 6.4 Visualization of root at foramen at bottom of U-turn.


    9781626238077_c006_f004.tif



    Fig. 6.5 Advancing cephalad with removal of ligament/medial facet in lateral arm of U-turn.


    9781626238077_c006_f005.TIF



6.4.5 Alternative Process of Gaining Epidural Access (Best at L5–S1)


Steps 1 to 8 above, followed by:


Dec 22, 2019 | Posted by in NEUROSURGERY | Comments Off on The Fundamental Open Surgical Method
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