Internet Outline of

Neurosurgery

E. R. Flotte MD, 2009

Please send comments and corrections to admin@flotte2.com

www.outlineofneurosurgery.com

Spinal Procedures

Spine Pathology

Spine Trauma

Spinal Infections

Spinal Dysraphisms

General References

· Benzel EC: Surgical Exposure of the Spine: An Extensile Approach, 1995

· Benzel EC: Biomechanics of Spine Stabilization: Principles and Practice, 1995

Grafts

· Woolf’s Law: Fusion potential is improved if graft is placed under compression

· Pseudarthrosis: failure of attempted fusion at 1 year post-surgery

· Osteoinductive: contains growth factors to stimulate osteoblasts

· Osteoconductive: acts as scaffold

· Osteogenic: contains bone progenitor cells

· Cortical bone provides structural support. Cancellous bone acts as a scaffold.

· Anterior grafts may be interbody grafts, strut grafts (i.e. corpectomy), or transvertebral grafts (i.e. lumbosacral)

Types

· Autograft: local, iliac crest, rib, fibula

o Anterior iliac crest harvesting:

o Anterior: Keep at least 1cm posterior to ASIS (anterior superior iliac spine) to avoid damaging the lateral femoral cutaneous n.

o Posterior

· Allograft: cadaveric iliac crest, rib, or fibula (structural) or morselized (non-structural).

o May be fresh-frozen (stored at -70) or freeze dried.

o No AIDS transmission since 1985, and none in freeze-dried allograft.

· Demineralized bone matrix: Grafton, Opteform, Dynegraft, Osteofil, DBX

· See Deutsch H N1/07S

Osteogenic Substances

· BMP has been shown in RCT to improve fusion rates and clinical outcomes for ALIF only (Burkus JK J Spinal Disord Tech 10/2002) – not for other lumbar fusion types (which are off-label uses)

· rhBMP7 may be available in the future

· rhBMP2 - recombinant human BMP2 - InFUSE, Medtronic Sofamor Danek: fusion rates of 95% in LIF

· rhBMP2 has been associated with some local swelling and swallowing difficulties, prompting Medtronic to issue a letter warning against the use of rhBMP-2 in the ventral cervical spine.

· As a general rule, negates effect of smoking

Cages

· May be titanium, PEEK, carbon fiber

o Titanium threaded fusion cages: Ray, BAK

o Titanium mesh cages

o PEEK: polyetheretherketone (aromatic benzene ring polymer). Radiolucent. Bioinert. Mechanics similar to bone.

o Carbon fiber: radiolucent.

o Allograft: cortical bone dowel (threaded or not), femoral ring

· Expandable cages: see Ragel BT ON11/07 (thoracoscopic) - VIDEO

· May be filled with autograft, BMP sponge, etc

o Autograft may be harvested by coring iliac crest

· Bioresorbable implants: HYDROSORB biodegradable polymer (DL-PLA) (Medtronic Sofamor Danek). See Neurosurgical Focus 3/04

Anesthesia

· Awake and/or fiber-optic intubation: used in patients with severe cervical spinal cord compression or instability to avoid injury during intubation

· Double-lumen endotracheal tube: used for thoracotomy (above T8), thoracoscopy

· Neuro-monitoring used generally when spinal cord damage is a significant concern (SSEPs, MEPs). Avoid paralytics with neuro-monitoring

· Cell-saver used when high blood loss is expected

Positioning

· Frames (Wilson, four-post) used for prone patients to avoid thoracic and abdominal compression.

· Andrews table used to position patient knee-chest

· Turning bed (e.g. Stryker frame, Jackson Table) may be used for combined anterior/posterior approaches to avoid repositioning

· Ischemic optic neuropathy can occur in prone position (especially in Trendelenberg), causing blindness. Caused by increased intraocular perfusion pressure. No effective treatment.

· SCDs/TEDs used

Corpectomy reconstruction options include:

1. Autograft or allograft strut: Proven durability for >6 mo survival for tumors. Disadvantages: Pseudoarthrosis, tumor invasion. Examples: Iliac crest, fibula.

2. Cages (titanium, PEEK, carbon fiber). May be left in place with infection generally.

3. Tailored AO construction plate with PMMA (aka Wesley Wedge). Plate placed AP for cervical, lateral for thoracic or lumbar.

4. Cervical: Polymethylmethacrylate (PMMA) with Steinmann pins, screws, or coaxial double-lumen (Chest-tube) as anchor.

· Gelfoam or fat placed over dura to prevent heat damage. Infection requires either removal or lifelong antibiotics

5. With or without adjunctive plating.

General Stabilization Principals

· Instrumentation is temporary stabilization to allow bony fusion

· Do not end long cervical or lumbar stabilization at apex or junction – i.e. C1, C7, L1. Creates long lever arms. (e.g. C3 to T1/2 OK)

· OK to end thoracic stabilization at T1 or T12 – already immobile

· Short stabilizations (e.g. C4 to C7 or shorter) generally OK

Occipitocervical Stabilization

· For occipitocervical instability due to trauma, postsurgical (e.g. odontoidectomy), degenerative (e.g. rheumatoid arthritis), neoplastic, or congenital (e.g. Down’s) causes

· Occipital plate, C2/3 screws (see below), rods.

o Axis curved titanium plate (Medtronic Sofamor Danek), Vertex devices (Medtronic Sofamor Danek), Summit system (Depuy Acromed), Mountaineer system (Depuy Acromed), CerviFix systems (Synthes Spine), and StarLock systems (Synthes Spine) (Nockels JN:S8/07)

o 4x8mm screws usually placed bicortical in midline keel of occiput – check preop CT head for thickness

· Historic: 1. CD horseshoe with either sublaminar or interspinous wiring. 2. Luque rectangle. 3. Contoured Steinman pin.

o Also C2-clivus plating

· C1 transcondylar screw (for occipitocervical dislocation)

· Incorporation of C1 lateral mass screws into occipitocervical instrumentation constructs does not seem necessary routinely. (Wolfla CE N9/07

)

· Recommended to incorporate C2 pedicle screws or C1–C2 transarticular screws for control of axial plane rotation. (Wolfla CE N9/07)

· AANS Course: Occipital Fusion Techniques (Harrop JS)

C1/2 (Atlantoaxial) Stabilization

· C1 -C2 rod-screw construct:

o Screws may be placed before reduction.

o Obtain thin cut CT C1-C3 to look at vertebral, size of pars/pedicle, etc

o Consider image guidance for screw placement

o C1 screws:

· C1 Lateral Mass Screw:

o Can sacrifice vs retract C2 nerve root.

o Can drill ring of C1 for pilot hole

o Slight (0-10°) medial and cranial angulation.

o Use 35-40mm screw (15-20mm in bone). Some use lag screw.

o Don’t go past posterior border of the arch of C1.

o C2 root injury may cause occipital hypesthesia

o AANS Course: C1 Lateral Mass Screw Placement Course (Florman J)

· C1 Pedicle Screw

· C1 arch screws reported (Donnellan MB JN:S12/08)

o C2 screws:

· Check preop thin-cut CT to determine possible screw location

· C2 Pars Screw: Pars must be seen in 4 cuts in sagittal plane. 14-18mm screw. Entry as for transarticular screw.

o Some patients have a narrow C2 pars or medially located foramen transversarium, precluding safe C2 pars screw placement

· C2 Pedicle Screw:

o 4x18-20mm screw. Entry: 14mm above C2/3 facet in middle of pars. Directed cranially and medially 20-30° (determined by intraoperative navigation)

o Contraindicated in 8% due to VA location. Questionable if risk of VA injury is less than pars screw.

· C2 Translaminar Screws: 3.5-4x30-40mm polyaxial screws, right screw rostral to left

o Laminar screws may also be used at other levels in adults (rarely in children) (Chern JJ JN:P2/09 (pediatric))

o Biomechanical Studies: Wright NM JSD2004, Reddy C JN:S10/07 (in vitro vs C2 pedicle)

o Case Reports: Chamoun RB N4/09 (Pediatric).

· Following all – C1-C2 fused (with Brooks, Sonntag, etc or laminar/lateral mass decortications and bone graft) and c-collar usually worn 4-6 weeks

· C1/C2 transarticular screws: 80-100% success.

o 4% vertebral a. injury per side – identify VA on preop CT.

· Transarticular screws contraindicated in 20% of patients bilaterally because of VA location

· VA most at risk if screw is misdirected caudally

o Contraindications: anomalous vertebral artery, C1 lateral mass comminuted fracture, C2 pars fracture. Difficult with thoracic kyphosis.

o Reduction required before screw placement.

o C1–C2 articular cartilage removed. Wire may be passed C1 lamina to allow retraction. Entry point is 2-3 mm above and 2-3 mm lateral to the medial aspect of the C2–C3 facet. 2.5-mm drill bit is directed sagittally, aiming toward the anterior arch of C1, using fluoroscopy. This requires a percutaneous approach from approximately the level of C7. 3.5-mm tap is used for the entire length of the trajectory to prevent possible anterior dislocation of the atlas during screw insertion. 35-40mm x 3.5-4mm fully threaded screw of the appropriate length is then inserted, stopping just short of perforating the anterior cortex of the atlas. The process is repeated on the other side. The laminae of both the atlas and the axis are decorticated, and overlaid with bone. Can be supplemented by sublaminar/interspinous wiring. Hard collar for 6 weeks

o Reviews: Haid RW N7/01 (Operative Nuances), JN:S2/05, N1/07S

o Videos: Haid RW N7/01

o Anterior C1/2 transarticular screws: used as salvage technique

· C1/2 rod/screw and transarticular screw constructs are biomechanically equal. Can do only 1-sided if necessary.

· Sublaminar/Interspinous Wiring: 60-100% success.

o Problems: risk of passing sub-laminar wires (spinal cord injury, durotomy), 25% Pseudoarthrosis

o Don’t pass wire under C1 with ventral compression

o All usually require intact posterior elements.

· Lasso technique may be used for missing arch of C1

o Postop halo used 3-4 months on most patients and all RA patients. Alternative is SOMI.

· Consider at 3mos check flex/ext in disconnected halo, and if stable collar x 4 weeks

o Gallie: bone graft notched placed over C1, C1 sublaminar wire looped around the spinous process of C2. Poorest biomechanical construct.

o Brooks: Sublaminar wires of C1 and C2 bilaterally. Two bone grafts beveled to fit the interlaminar space under the wires.

o Sonntag: Notched bone graft fit into the interlaminar space. C1 sublaminar wire passed around C2 spinous process.

o Halifax interlaminar clamps: Usually used with bilateral bone grafts. Excellent anteroposterior stability, less rotational stability than either Brooks or the Magerl techniques

· C1/2 Anterior Harms Plate: Less biomechanically secure. Requires posterior wiring in addition.

· Verterbral Artery Injury: leave screw in place and tamponade. Abort procedure - do not place contralateral screw (some complete fusion with bone graft ispliateral) and get angiogram. Consider sacrificing vertebral artery, endovascular occlusion, or heparinization. Some place screw on side on non-dominant vertebral a. first.

· Reviews: Menendez JA N1/07S – See Figures below

· CNS Course: Occipital-C1-C2 Fixation: Flexibility and Rigidity (Resnick DK)

Transoral Approach

· Used for clivus to C2.

· All oral or dental infections must be treated preoperatively. Some use clorohexidine mouth wash preop. Some use antibiotics for 48-72 hrs postop.

· Patient must be able to open their mouth >25mm to avoid splitting mandible (Rheumatoid patients may have TMJ syndrome)

· Consider preop respiratory and speech evaluations and oropharyngeal cultures.

· Supine. Fiberoptic oral intubation. Neck slightly extended. Prep oro/nasopharynx. Crockard or Dingman retractor. Retract soft palate by suturing to red rubber catheter passed thru nares.

· Palpate tubercle of C1. Incision in posterior pharynx from C1 arch to base of C2. Close incision in 1 layer.

· Cut transverse ligament, tectorial membrane if intradural.

· Can combine with Lefort/maxillotomy, transoral-transmandibular or high retropharyngeal (incise/resect soft palate) approaches

· Odontoidectomy: Remove C1 arch and dens with drill/ronguers. Pannus may be adherent to dura. Most patients require occipitocervical fusion (simultaneous or staged).

· Reviews: Mummaneni PV N5/05 (Operative Nuances)

· Videos: Mummaneni PV N5/05

Anterior cervical approach

· Aka anterolateral, Smith-Robinson approach

· C3-C7/T1 only. Look for sternal notch in relation to vertebrae on imaging for lower limit.

· Supine. Neck slightly flexed. Usually with horseshoe headholder (or donut, pins)

· Incision: Transverse incision used for 1-2 levels – in Langer’s lines. Carotid incision (longitudinal) used for 3 or more levels (generally)

o Right side – higher risk of recurrent laryngeal n. palsy. Left side – risk of thoracic duct injury.

o If patient has vocal cord paresis approach from side ipsilateral to paresis

o Sonntag recommends right side unless patient has a previous left side incision (Sonntag VKH N10/01)

· Platysma divided. Blunt dissection used between sternocleidomastoid/carotid sheath and medial structures. Omohyoid can be divided.

· Prevertebral space dissected. Longus coli muscles dissected laterally.

o Vertebral artery and sympathetic plexus at risk laterally (later may cause Horner’s syndrome – lies on anterior surface of longus coli)

Anterolateral Cervical Approaches

· Note: terminology of approached vary among sources

· Used for lateral vertebral pathology or access to vertebral artery

· Approaches to upper cervical spine (Clivus to C3):

o Extrapharyngeal (Lateral transcervical extrapharyngeal) (McAfee): submandibular (or T) incision

o Retropharyngeal approach

o Far-lateral suboccipital approach (aka dorsolateral, extreme lateral transcondylar, transjugular, dorsal lateral suboccipital condylar)

· Anterolateral (ventrolateral) cervical approach: as with standard anterior cervical approach, but longus coli retracted medially to expose transverse and lateral uncinate processes and vertebral artery. Sympathetic chain mobilized.

o Alternative ventrolateral cervical approach: SCM retracted dorsally (posterior) or divided, carotid sheath retracted ventrally (anterior). Otherwise as above.

· Dorsolateral cervical approach: Lateral incision. SCM and carotid sheath retracted ventrally (anteriorly) (e.g. Hodgson, Elkin & Harris)

· Anterolateral approach to V2 (Bruneau M ON10/05 - VIDEO) and V3 (Bruneau M ON2/06 – VIDEO) vertebral artery

· Anterolateral cervical foraminotomy/discectomy: Bruneau M ON2/06 - VIDEO

Odontoid Screw

· For minimally displaced Type II odontoid fractures.

• Contraindicated in: disruption of the transverse ligament, C1 ring fracture, comminuted fracture of atlantoaxial joint, Type 2 fractures with (anterior-inferior) oblique or comminuted fracture lines, irreducible fractures, associated thoracic kyphosis, fractures > 6 mos old, and pathological fractures. Relative CI: osteoporosis, barrel-chest/obese.
• Check MRI preop to r/o transverse ligament disruption

· 88% fusion rate in acute fractures (25% in fractures over 6mos old).

· One or two screws used (biomechanically equivalent).

· Complications: screw pullout or fracture.

· Technique: Anterior cervical approach. Neck extended. External reduction under flouro. Consider 2 flouros – A/P & lateral. Transverse incision at C5/6. Dissect to C2 prevertebral space. May roughen fracture edges with curette. K-wire placed inferior C2. 8mm hollow drill used to create working channel in rostral C3. 3mm drill passed thru guide through apical cortex. 4mm diameter lag screw (threads above fracture line – measure fragment length). Can use 2^nd screw 3-4mm away.

· Consider collar postop.

Anterior Cervical Foraminotomy

· A.k.a. Jho procedure

· Anterolateral cervical foraminotomy/discectomy: Bruneau M ON2/06 - VIDEO

Anterior Cervical Discectomy and Fusion (ACDF)

· Smith-Robinson Technique

· Anterior cervical approach

· Distraction pins usually placed in adjacent vertebral bodies

· Discectomy performed. PLL usually resected and foraminotomies performed.

· Fusion rate unchanged with graft, but kyphosis dropped (62.5 to 42%) – no RCT.

o Discectomy alone has a shorter operation time, hospital stay, and post-operative absence from work than discectomy with fusion, while there is no statistical difference for pain relief and rate of fusion.(Cochrane)

· Interbody spacers include: allograft (iliac crest), autograft, cages (carbon fiber or PEEK filled with autograft or BMP sponge)

o Fusion techniques that use autograft give a better chance for fusion than interbody fusion techniques that use a cage, but other outcome variables could not be combined. (Cochrane)

· Cages for single level ACDF showed better fusion rates, worse for 2 levels (Hillebrand AS JBJS 1999)

· Anterior Cervical Plating improves fusion rate from 90% to 96% for single-level and 72% to 90% for 2-level

o 3 RCT: Savolainen et al. and Zoega et al. found no significant differences in clinical outcomes, but a decreased tendency for the development of kyphosis in the ACDF plus plate group. Grob et al. found better graft height preservation in the plated group. The plated group did slightly, but not significantly, better than the nonplated group in terms of functional outcome measures.

o Fusion rates for one- and two-level arthrodesis with allograft and plate were 96% and 91% (compared with 90% and 72% without plating)

o Plating may help avoid the need for external orthoses and allow a quicker return-to-work.

o Necessity of routine postoperative xrays following ACDF has been disputed (Ugokwe KT JN:S8/08)

· Complications:

o Hoarseness: Usually temporary (paratracheal swelling).

· Recurrent laryngeal nerve loops around subclavian a. on right and aortic arch on left, runs between esophagus & trachea, more variable on right.

· Singers & speakers – consider using posterior approach to avoid recurrent laryngeal n. injury

· In revision cases, if one wishes approach from the contralateral side, laryngoscopy to assess the functioning of the vocal cords is important to exclude a previous nerve injury

· May take up to 4 months to resolve

· Persistent cases: laryngoscopy to confirm vocal cord paralysis. Vocal cord injection or medialization can be performed.

· Re-inflating ET tube cuff after retractor placement may prevent pressure on the endolaryngeal segment of the RLN

o Thoracic duct may ascend to C6 on left behind the carotid sheath. Ligation carries 50-80% mortality.

· Vacarro AR et al 2004 recommend ligating injured thoracic duct with 3-0 or 4-0 suture. Site of leakage can be identified with positive pressure in Trendelenberg.

o Durotomy: place fascial graft or onlay (e.g. Duragen) on top of dura, HOB elevated, consider LD.

o Horner’s syndrome: sympathetic plexus runs in longus coli laterally. Usually resolves.

o Graft extrusion: usually doesn’t require reoperation unless symptomatic.

o Adjacent level disease: 20% develop requiring operation by 10 years (higher at C5/6, C6/7).

· Hilibrand reported that repeat surgical intervention was necessary for 3% of patients per year for adjacent segment disease after ACDF, and 10 years after ACDF 25% of the patients reported symptoms from adjacent segment disease. Goffin revealed that 92% of fused patients demonstrated radiographic evidence of adjacent segment degenerative disc disease 5 years after surgery.

o Pseudoarthrosis: failed fusion may cause persistent neck pain

o Esophageal injury: consider occult injury with recurrent polymicrobial wound infections

· Diagnosis: esophagram, esopagoscopy

· Treatment: Repair. Postop drainage. Antibiotics. Extraoral feeds.

o Tracheal injury:

· Surgical repair if transmural >1cm

· Intubation with cuff below laceration

o Instrumentation failure: Plating of >3 levels have higher risk of caudal screw pull-out. May be supplemented with posterior stabilization.

o Vertebral artery injury: during foraminotomy or uncovertebral joint resection.

· Preoperatively note location of vertebral artery on imaging (r/o anomalous artery)

· Treatment: direct repair, ligation, packing (with followup angio and possible endovascular occlusion).

· Postop mimics hematoma. Aspiration is milky. NPO – start IVFs. If drain present convert to gravity (not suction)

· 0.5% risk of morbidity with ligation

o Carotid artery injury: treated with direct repair (internal jugular may be repaired or sacrificed)

· Review: Sonntag VKH N10/01 (Operative Nuances), Russell SM N5/04 (Operative Nuances)

· Video: Sonntag VKH N10/01, Russell SM N5/04

Cervical Arthroplasty

· Cervical Artificial Discs: Indicated for discectomy for radiculopathy or myelopathy.

o Recommended use in US (Prestige) is single-level disc herniation in younger patient

o Outside of US, multilevel arthroplasties are done

o Requires the posterior elements, such as the facets andligaments, to be intact and functional. Patients with cervical kyphosis, cervical spondylolisthesis with incompetent facets, severe multilevel cervical spondylosis (three or more levels), severe osteoporosis, or cervical trauma are typically excluded.

o Patients with cervical kyphosis or incompetent cervical facets with spondylolisthesis are at risk for migration of the arthroplasty because of abnormal local shear strains

o Patients with severe multilevel spondylosis or ankylosis are unlikely to experience the benefits of arthroplasty because their baseline cervical range of motion is very limited.

o Patients with osteoporosis are at risk for pistoning of the implant through the weakened vertebral endplates.

o Trauma patients with ligamentous or facet injury are at risk for device migration

o There are four primary reasons to consider revision of an arthroplasty: residual or new radiculopathy, ankylosed joint (no motion of the implant), subsidence of the implant through the endplates, and migration of the implant out of the disc space.

· Mummaneni PV JN:S3/07: Multicenter RCT: Arthroplasty had higher rate of neurologic success, lower secondary revision and supplemental fixation. 2-year followup. (editorial by Benzel EC)

· The Cervical Spine Study Group developed a nomenclature system for cervical arthroplasty. Artificial discs may be categorized by the following criteria: articulation, material, design, fixation, and kinematics.

o Nonarticulating, uniarticulating, or biarticulating.

o Metal on metal design (PRESTIGE ST, Medtronic Sofamor Danek), a metal on polymer design, such as polyurethane or ultra-high-molecular-weight polyethylene (BRYAN, Medtronic Sofamor Danek; ProDisc-C, Synthes), a ceramic on polymer design, or a ceramic on ceramic design.

o Modular, meaning that they have replaceable components, or non-modular

o Some discs have supplemental vertebral body screw fixation. Some promote biological bone ingrowth at the disc-endplate interface.

o Discs may be constrained, semiconstrained, or unconstrained in terms of motion.

· Devices:

o Prestige ST Cervical Disc System (Medtronic Sofamor Danek), FDA approved.

o Disc Implantation Technique: see Mummaneni PV ON4/07 (Operative Nuances)

· Reviews: Neurosurgical Focus 9/04, Mummaneni PV ON4/07 (Operative Nuances)

· Videos: Mummaneni PV N4/07

· Audio: Disc Arthroplasty – Traynelis VC

Cervical Corpectomy

· Commonly used for tumors, body fractures, OPLL

· Anterior Cervical Approach

· Posterior transpedicular approach: Ames CP JN:S2/09

· Generally middle 1/2 to 2/3 of vertebral body is removed, lateral elements left in place

· Corpectomy reconstruction options

• Allograft is sufficient for up to two levels.
• For 3 or more level corpectomy, posterior instrumentation is required to avoid graft failure and pseudoarthrosis (Mummaneni PV N1/07S)
• Chance of instrumentation failure (anterior only): 2-level = 9%; 3-level=50% (Vaccaro AR JSD 1998)
• Usually supplemented with anterior cervical plating

· Reviews: Cooper PR N11/01 (Operative Nuances)

Anterior Cervical Plating

· Generally used after ACDF, corpectomy

· Screws placed in vertebral body under fluoroscopic guidance

o First generation plates (Caspar) required bicortical screw purchase to prevent back-out. Newer plates contain screw-locking mechanisms

· “Semi-constrained, rotational” dynamic plates use variable angle screws for dynamism, include the Atlantis (Medtronic Sofamor Danek), A-line (Medikon), and Codman

· “Semi-constrained, translational” dynamic plates systems allow the screws to translate rostrocaudally within a slot, and includes the Premier plate (Medtronic Sofamor Danek), the DOC system (Depuy Acromed), and the ABC plates (Aesculap), It is not known whether the rate of fusion is different from that of a rotational plate

· “Uniplates” (one screw per level) used (Depuy Acromed)

· Butress plates used in long segment stabilization cover only the cranial/caudal intact VB and part of the strut graft. Usually used with posterior stabilization.

Posterior Cervical Approaches

· Patient usually prone, “Concorde” (or lateral)

· Pin-fixation of the head usually used

· Midline incision. Ligamentum nuchae divided. Paraspinal muscles dissected sub-periosteally.

· Creeping fusion extension may occur in children when unnecessary levels are exposed

· Vertebral artery injury: If possible, primarily repair. If not ligate or clip VA proximally & distally (12% mortality – esp. w/contralateral VA hypoplasia).

Cervical Laminectomy

· May be performed with drill, Kerrison or Leksell rongeurs.

· Consider concurrent stabilization with lateral mass screws & rods or plate, especially if patient is young or instability exists.

· Dissociated Motor Loss (DML) (C5 motor radiculopathy) is a complication of extensive cervical decompressions with C5 motor weakness, shoulder pain and no sensory loss. Occurs 24-48 hours Postop. Treatment is immobilization and steroids. Etiology is unknown. Improvement generally occurs over months in two-thirds.

Cervical Laminoplasty

· Lower incidence of kyphosis.

· Consider especially for young patients

· Open side completely drilled, hinge side scored with drill. 10-15mm Allograft rib spacers placed. Collar x 3mos. Consider removing spinous processes.

· Preop kyphosis, abnormal motion on dynamic xrays, or OPLL >60% of canal diameter are contraindications (Wang MY N1/04)

· Causes 30-50% decreased range of motion

· Reviews: Wang MY N1/04 (Operative Nuances)

· Videos: Wang MY N1/04

Posterior Cervical Foraminotomy

· For unilateral osteophyte, facet hypertrophy, extruded disc causing unilateral radiculopathy (not myelopathy)

· Concorde or sitting position.

· Scoville retractor or endoscopic (Adamson TE JN:S7/04)

· 1/3 to 1/2 of lamina and facet removed. Resect superior articular facet to pedicle Riew KD N1/07S

· Case Series: Jagannathan J JN:S4/09 – editorial – Figure 1

· Reviews: Russell SM N3/04 (Operative Nuances), Riew KD N1/07S

· Videos: Russell SM N3/04

· AANS Course: Minimally Invasive Posterior Cervical Discectomy and Foraminotomy (Foley KT)

Posterior Cervical Stabilization

· Lateral mass screws:

· 4mm x 12-14mm screws. Used with rods or plates.

· Used C3 to C7.

· At C2 and C7, the lateral masses are small and the vertebral artery at C2 traverses laterally and at risk from a lateral mass screw.

· Magerl technique: screw begins 1mm medial and rostral to the center of the lateral mass, and is directed 25° laterally (towards the superior-lateral corner of the facet) with a rostral inclination that is parallel to the facet joints (25°). More commonly used.

· Roy-Camille technique: screw entry point is at the center of the lateral mass and is directed 10 degrees laterally, with no rostral-caudal inclination

· Rod-screw systems include: Vertex system (Medtronic Sofamor Danek), Summit system (DePuy Acromed), Axon system (Synthes), Oasys system (Stryker), and the Ascent System (Blackstone Medical).

· Cervical pedicle screws advocated by some, but are technically difficult.

· C2: Starting point identified by using a Penfield #4 with a small cottonoid to slide up along the medial border of the pedicle. With direct palpation of the medial wall, the pedicle is then drilled with a 2-mm high-speed burr. Roy-Camille et al. recommend that the pedicle be drilled approximately 15 degrees medially and 35 degrees superiorly. Howington et al. found it to have a medial inclination of 35 degrees and a superior angulation of 39 degrees. Ebraheim et al. have demonstrated that the direct palpation of the C2 pedicle is a much safer guide than trajectory guidelines.

· C7: perform lamino-foraminotomy to directly palpate the superior, medial, and inferior borders of the C7 pedicle

· C7/T1 pedicle screws stronger than C7 lateral mass/ T1 pedicle screws. Above C6 makes no difference.

· Laminar hooks and sublaminar wiring have risk of neurologic deficit.

· Interfacet wiring (Wiggins GC N1/07S)

· Intraspinous wiring +- Luque rectangle

· Interlaminar (Halifax) clamps

· C7 transfacet screw: Horn EM JN:S8/08

Cervicothoracic Approaches (T1-T4)

· Transmanubrial: Anterior cervical approach with manubrial (upper sterna) osteotomy (to T2/3)

· Supraclavicular: transverse supraclavicular incision, SCM and omohyoid detached from clavicle. Limited exposure to lateral C7/T1.

· Transsternal (Median sternotomy) (to T4)

· Transaxillary

· Lateral parascapular

· Reviews: Le H NF11/03

Thoracic Approaches

Posterior:

1) Laminectomy

Posterolateral:

2) Transpedicular

3) Costotransversectomy

4) Lateral extracavitary

Anterior:

5) Transthoracic / thoracoscopic

Thoracic Laminectomy

· Used primarily for dorsal pathology

· Midline incision. Spinous processes and lamina removed.

Posterolateral Transpedicular Approach

· Superior and inferior hemi-laminectomies and medial facetectomy. Pedicle inferior to disc drilled out.

· Also transfacet pedicle-sparing

Costotransversectomy

· Resection of transverse process and rib.

· Risk of damage to significant radicular artery to spinal cord - Artery of Adamkiewicz

· Prone on frame or chest rolls. Curvilinear incision centered over the herniated level. Erector spinae muscles cut transversely to expose the ipsilateral laminae +- hemilaminectomies. Transverse process and rib head are then dissected and resected. Neurovascular bundle on the undersurface of the rib is preserved.

· Rib articulates with the disc space above the same numbered vertebral body (i.e. rib # = lower vertebral body #).

· Does not allow sufficient exposure for strut grafting

· Lateral extracavitary approach: involves removal of 8-10cm of rib, facet and pedicle. Allows corpectomy with strut graft.

Transthoracic Approach (Thoracotomy)

· Assess pulmonary function preop

· Side of approach:

o T4-6: right approach (heart)

o T7-T9: left approach (aorta easier to mobilize than SVC)

o Or as dictated by pathology (e.g. scoliosis)

· Lateral decubitus. Axillary roll used.

· Corpectomy: Thoracotomy made through rib bed two levels above the involved VB (or rib directly horizontal to level in midaxillary plane)

o For long exposures, rib at proximal end can be removed (e.g. 5^th rib for T5-T12)

o For discectomy, rib that leads to disc can be removed (e.g. 8^th rib for T7/8)

· Parietal pleura incised over the length of the spine

· Disc/VB level confirmed with fluoroscopy. First palpable rib is 2^nd rib.

o Segmental vessels run over vertebral bodies. Discs form ridges between VBs (“hills-and-valleys”)

· Segmental vessels may be ligated – in anterior 2/3rds of vertebral body.

o Temporary occlusion of segmental vessels with spinal cord monitoring may be used before ligation (e.g. with prior surgery and vessel ligation)

· Chest tube placed in anterior mid-axillary line at least 2 interspaces from the incision

o Generally left in place for 48-72 hours (<30-100cc drainage per 8 hours)

o CSF leak: Put chest tube to water seal and remove ASAP. Place lumbar drain at surgery and pull after CT. Also use fibrin glue/Gelfoam etc.

· Thoracic duct may be injured with leakage of creamy white chyle. May be repaired or ligated

o Chylothorax: may be diagnosed postoperatively by chest tube drainage. Continue chest tube drainage, decrease fat intake (consider hyperalimentation). Re-exploration for failure.

Thoracoscopic Approach

· Review: Oskouian RJ N1/02 (Operative Nuances)

· Video: Oskouian RJ N1/02

Thoracic Discectomy

· Approaches:

o Transpedicular or posterolateral approaches (e.g. costotransversectomy) if lateral

o Transthoracic or thoracoscopic if midline or calcified

o Essentially never approached via laminectomy.

· Important to obtain preoperative scout MRI from the sacrum to count levels intraoperative (also count ribs)

· Fusion after thoracic discectomy is controversial. Considered for kyphosis, instability, multilevel surgery.

· Rib autograft and plate may be used (some use for patients with back pain)

· Reviews: Mummaneni PV CN11/1/01

· Videos: CNS University of Neurosurgery

Posterior Thoracic stabilization

· Thoracic Pedicle Screws

· Pedicle located at intersection lines on mid-transverse process and lamina/TP junction

· Trajectory: T1 = 25-20° medial, T2 = 15° medial, others 0°

· Screw size: diameter T3-T9 = 4.5-5mm; T10-T12 = 6-6.5mm;

· Use fluoroscopy and/or neuronavigation

· Pedicle exposed by drilling cortex. Pedicle tapped with curved awl (or curette or drill). Pilot hole drilled. Ball-tipped probe used to inspect hole walls.

· “In-Out-In” Technique: lateral cortex perforated, medial cortex kept intact

· Screw inserted to 60-70% VB diameter.

· Screw length (average) T1-4 = 25mm, T5-9 = 30mm; T10-12 = 35mm

· Complications:

· Screw misplacement: any screw causing neurologic injury should be immediately removed

· Laminar wires, Sublaminar hooks have higher risk of neurologic injury

· Historic: Harrington (1960), Luque (1980s), Cotrel-Dubousset (1984)

Lumbar and Thoracic Corpectomy

· For vertebral body fractures, neoplasm, infection

· Via anterior/anterolateral approaches: Transthoracic, anterior lumbar

· Corpectomy reconstruction options

· Anterior thoracolumbar plates/rods: Kaneda, Z-plate (Sofamor-Danek), CASF, University plate (Depuy-Acromed)

o Plates: used for 1-2 levels

o Get bicortical purchase with screws (<5mm), parallel to endplates and PLL

· See Mummaneni PV CN5/30/02

Lumbar and Thoracic Spondylectomy

· Complete excision of vertebra

· Often performed for vertebral tumor (primary, single met)

Anterior Lumbar Approaches

· Generally done for vertebral body tumor, fracture, ALIF

· Anterior lumbar/thoracic approach: D’Aliberti G JN:S11/08

Transdiaphragmatic Thoracolumbar Approach (T10-L2)

· Approach from left or side of pathology

· Lateral decubitus position. Level of pathology placed over “break” in the table.

· Incision over 10^th rib to costochondral junction.

· Peritoneum mobilized from undersurface of diaphragm and retracted anteriorly

· Diaphragm transected at its insertion.

· Note: Some feel artery of Adamkiewicz may be safely sacrificed anterior to mid-body, due to collaterals

Retroperitoneal lumbar approach (L1-S1)

· Approach from left (or side of pathology)

· Incisions:

o Median/Paramedian (L2-S1): Supine. Rectus sheath and transversalis fascia incised. More vascular injuries.

o Flank (L1-S1): Lateral decubitus, left side up. Entire abdominal wall mm. transected. Dissect to preperitoneal fat. Cut lattisimus dorsi.

· Sweep ureters medially

o L4/5: ligate external iliac vv. and iliolumbar v.

· L5/S1: work in aortic bifurcation. Ligate middle sacral vv. (bipolar – avoid bovie to avoid damage to superior hypogastric plexus). Both ureters retracted to right.

· Ureteral injury can be confirmed with 5cc injection of intravenous methylene blue dye – appears in surgical field. Ureteral stent may be placed preoperatively to identify ureter.

· Retraction or damage to psoas muscle may cause hip flexion weakness and difficulty climbing stairs. Gradually improves without treatment generally.

· Sympathetic chain lies on lateral VB – damage may cause LE sympathetic dysfunction (heat, swelling in ipsilateral leg)

o If ipsilateral leg is cool and painful with absent pulses order arteriogram immediately

Transperitoneal lumbar approach (L5-S1)

· May be done laparoscopically

· Some recommend L5 stabilization posteriorly if possible due to anterior difficulty

· Risk of retrograde ejaculation due to superior hypogastric (sympathetic) plexus (not erectile dysfunction)

Lumbar discectomy or decompression

· Approaches:

o Standard: Midline incision, Paraspinal muscles dissected from spinous process. Standard or tubular retractor used

o “Transmuscular”: Off-midline incision. Sequential dilators used for tubular retractor

· May involve laminotomy, facetectomy, foraminotomy, and/or discectomy

o Bilateral medial facetectomies may be performed via unilateral laminotomy (described by McCulloch)

· Case Series: Sasai K JN:S12/08, Weiner BK Spine 1999

· Usually GETA, can be done under spinal anaesthesia (McLain RF JNS1/05)

· Consider 250mg solumedrol, Marcaine epidurally

· Review shows greater long-term recurrent back and leg pain after aggressive discectomy, more recurrent HNP after limited discectomy McGirt MJ N2/09

· Investigational Adjuncts:

o Annulus closure (suture with or without fibrin glue, cyanoacrylate glue (Dermabond), Anulex Exclose system, etc.) has not been shown to improve outcome (Heuer F JN:S9/08)

o Nucleus replacement have risk of extrusion

· Complications:

o Great vessel injury: 0.01-0.1%. Symptoms: Refractory hypote