Introduction
Posterior spinal decompression is one of the most common surgical procedures to release neural structures when nonoperative treatment has failed and is usually the procedure performed for degenerative conditions such as spinal stenosis, especially in middle-aged and elderly patients. It is one of the most common spinal surgeries among cohorts more than 65 years of age. The classical laminectomy constitutes a central, facet joint sparing laminectomy. The spinous process and the lamina are removed limited laterally to the medial part of facet joints. There was no benefit in preserving the midline structures.The central canal, the lateral recesses, and the neural foramina need to be decompressed for good clinical recovery and prevention of failed back surgery syndrome.
Currently, there are several techniques to accomplish posterior spinal decompression, such as open or minimally invasive laminectomy, hemilaminectomy, laminotomies, and laminoplasty. Decompression techniques classify as direct and indirect; direct procedures involve those techniques with visualization of the dural sac during the surgery, such as laminectomy. On the other hand, indirect decompression takes place without dural sac visualization. Laminectomy alone or associated with fusion is one of the most common procedures performed by a spinal surgeon.
The goals of the surgery include:
- Reduce neurological claudication
- Halt clinical deficits and
- Promote functional ambulation.
Anatomy and Physiology
Proper knowledge of the posterior vertebral arch and laminae anatomy is imperative to understanding the principles of laminectomy.
The laminae belong to the posterior vertebral arch, extended medially from the base of the spinous process to the junction between the superior and inferior facet joints, acting as a stabilization structure of the spine in association with the facet joint and also as a spinal cord and nerve root protective layer. The laminae's general anatomy consists of a superior and inferior border, an anterior surface in contact with the medullary canal, and a posterior surface that serves as erector spinae muscles attachment. The shape and thickness of the laminae vary according to the anatomical region. Laminar height tends to decrease from C2 to C4 and then increases towards a peak at T8. From T9 to L4 tends to decrease in height and increase in length having at L5 the lowest lumbar height; on the other hand, from cervical to lumbar, laminae width decreases progressively up to the narrowest at T4 in the thoracic region and then increases steadily to reach the widest at L5.
Regarding the thickness, it increases from the cervical to lumbar regions.
A better understanding of the laminae anatomy in different spinal regions may improve surgery success and avoid iatrogenic complications such as nerve root or spinal cord injury.
Indications
The main indication for laminectomy is the presence of spinal canal stenosis; spinal canal narrowing has multiple etiologies, such as congenital, metabolic, traumatic, or tumoral; however, degenerative stenosis is the most common cause. According to Wiltse, spinal stenosis can also be classified into central stenosis, lateral recess, foraminal and extraforaminal stenosis. Also, Lee et al. classified the lateral region into three zones of nerve root compression: entrance zone (lateral recess), mid zone (foraminal region), and exit zone (extraforaminal region) in order to clarify anatomy and surgical strategy. Laminectomy is especially effective for the treatment of central and lateral recess stenosis.
Central stenosis is the most common, and the main symptom is neurogenic claudication, which includes pain, tingling, or cramping sensation in the lower extremity. On the other hand, lateral recess, foraminal, and extraforaminal stenosis may cause radiculopathy, patients with central stenosis may experience more symptoms in standing position and during walking, and pain is usually relieved by leaning forward or in a sitting position. In cases of central stenosis, straight leg raising and femoral nerve stretching test are usually normal.
When symptoms derived from stenosis do not respond to conservative treatment, surgical management such as decompression with or without fusion is usually a consideration.
Fusion techniques are required when stenosis is associated with spinal instability, degenerative or isthmic spondylolisthesis, kyphosis, or scoliosis, as laminectomy alone may increase the risk of spinal instability in these conditions. However, in cases of low-grade degenerative spondylolisthesis, the literature exhibits variable results regarding the risk of instability after laminectomy alone; some studies support fusion in cases of degenerative spondylolisthesis. On the other hand, Wang et al., in a recent meta-analysis, found no increased risk of instability after laminectomy, especially in patients without predominant symptoms of mechanical back pain and after minimally invasive procedures.
Other important indications for laminectomy are primary or secondary tumors, infection (peridural abscesses), trauma (fractures that compromise the spinal canal), and stenosis associated with the deformity.
The radiological armamentarium required in the workup includes:
- CT-criteria for central stenosis include anteroposterior diameter ( 10 mm) and cross-sectional area ( 70 mm2) of spinal canal.
- MRI –Gold standard imaging modality
- Dynamic flexion /extension films- to rule out instability and spondylolisthesis
- EMG- for differentiating distal neuropathies
- Plan X-ray- hip and knee- confounding osteoarthritis
The causes of spinal stenosis can be categorized as:
- Congenital: Achindroplastis dwarfism
- Acquired:
- Degeneration
- Trauma
- Space occupying lesions: Tumors, cysts
- Osseous lesions: Paget and Ankylosing spondylitis.
Indications for laminectomy include:
- Central or lateral canal stenosis refractory to 12 weeks of medication, physical therapy, and injections[11]
- Presence of intractable pain or progressive neurological deficits
- Presentation with cauda equina syndrome
Contraindications
- Spondylolisthesis
- Scoliosis and
- Lateral listhesis
Poor surgical candidates include:
- Patients with multiple medical comorbidities
- Patients with depression, compromised walking, and concurrent scoliosis
Equipment
- Standard radiolucent table with spinal frames and foams pads
- C-arm to localize level and minimize skin size incision
- Laminectomy instrument set (bone cutting rongeurs, high-speed burr, Kerrison rongeurs, forceps, ball tip, angled spatula spreader, bayonet-shaped curettes, hollow probes, tubular retractors, and dilators for MIS approaches)
Personnel
- One or two spinal surgeons, a registered OT nurse staff, and anesthesiologists
- Neuromonitoring is usually a recommendation in cervical or dorsal laminectomies and lumbar cases when there is an increased risk of nerve injury
Preparation
Laminectomy is performed with the patient in the prone position on a support frame with foam pads for nipples and ASIS (anterior superior iliac crest spine), leaving the abdomen free, avoiding abdominal pressure decreases epidural venous pressure and, therefore, surgical site bleeding.
Arms are positioned at 90 degrees abduction and flexion to prevent axillary nerve injury.
Technique or Treatment
Laminectomy can be performed through a traditional open approach or with a minimally invasive technique.
The traditional open approach requires a posterior midline incision (3 to 4 cm in length for a single level) and subperiosteal dissection along spinous processes to detach and retract paraspinous muscles from the spinous processes medially to the lateral laminar border avoiding damage to the facet joint. Spinous processes may be resected along with dorsal laminae to expose ligamentum flavum with bone cutting rongeur or a burr, resection of ligamentum flavum is possible with Woodson elevator and spatula, and medial facetectomies can be performed to decompress the lateral recess. The foraminal region can is reachable with Kerrison rongeurs. Use of a ball tip or angled probe help to assess foraminal size. Great care is necessary to avoid damage to pars interarticularis and more than 50% of the facet joint to decrease the risk of instability. The decompression procedure is usually complete upon confirmation of the dural sac, exiting, and descending nerve roots.
Minimally Invasive Surgical (MIS) techniques include laminotomy and microendoscopic laminotomy with tubular retractors. Contemporary literature supports these procedures resulting in better preservation of posterior musculature, decreased intraoperative bleeding, and postoperative pain.
Even though MIS approaches may have some early outcome advantages over open procedures, the economic value and cost-effectiveness of MIS require further investigation.
A recent systematic review compared conventional laminectomy with three different techniques that avoid removing the spinous process (unilateral laminotomy, bilateral laminotomy, and split spinous process laminotomy). A decreased postoperative back pain for bilateral laminotomy and split spinous laminotomy was found; however, there were no observable clinically significant differences. Further, there was no difference in terms of hospital length of stay, operative time, and complications of these techniques compared to conventional laminectomy.
The salient surgical steps in classical decompressive laminectomy can be summarized as follows:
- Prone positioning
- The abdomen should be made free of any undue pressure
- Anatomical localization aided with fluoroscopy
- Superficial tissue and muscle dissection to reach the spinous process
- Subperiosteal dissection of lamina-not exceeding axis of facet joints in classical laminectomy and not exceeding tip of the transverse process in others
- Spinous process removal via large rongeur or Horsley bone cutter
- Removal of the lamina via Leksell rongeur starting from the inter-laminar space
- Removal of thickened ligament flavum via Kerrison rongeur
- A high-speed drill to thin the lamina followed by its removal via Kerrison can also be undertaken
- Undercutting of medial facet and decompression of respective foramina
- Layered wound closure after ensuring hemostasis and placement of a drain
Complications
Instability: Damage to the pars interarticularis is a risk. Damage to more than fifty percent of facets on both sides or complete facets on one side intraoperatively mandates fusion surgery. Since L1-3 has a narrow surgical corridor for decompression, preservation of pars is of paramount importance at these levels.
Bony Re-growth
Kyphosis: due to disruption of posterior tension banding function of posterior Osseo-ligamentous complex.
Spinal epidural hematoma: maximum risk at the L2/3 level.
Dural tear: The incidence is 3.1% to 13% and 8.1% to 17.4% for primary and revision surgery, respectively. It increases the risk of surgical site infections, postoperative deficits, and delirium. The most location is the lower surgical field near the nerve root, followed by the dorsal sac.PMC4206814 Previous surgery and older age were found to be risk variables. The dural closure technique does not impact revision surgery rates or its complications. Primary repair followed by bed rest is advocated. Minimal access surgeries produce minimal dead space, reducing the risk of pseudomeningocele and CSF fistula.
Mortality: incidence of 0.5 to 2.3%.
Clinical Significance
Laminectomy is one of the most common procedures performed among spinal surgeons to treat spinal stenosis. This technique, correctly performed, correlates with symptomatic improvement and early recovery with relatively low complication rates. Even when the benefits of surgical versus nonsurgical treatment in lumbar stenosis have not been proven. [Level 1] Laminectomy remains an effective surgical technique for various conditions affecting the spinal canal, such as tumors, epidural abscess, and spondylotic myelopathy.
Results of the Procedure
- The success rate of 90% with a patient satisfaction rate of above 75%
- Pain and weakness resolve early, whereas dysesthesias may take up to two years
- Reoperation Rate-18% within five years
Causes of Failure
- Adjacent segment stenosis
- Disc herniation
- Spondylolisthesis
- Re-stenosis
Variants of Classical Laminectomy (high-risk factors precluding true decompression)
- Bilateral laminotomies
- Skip laminectomy
- Split spinous process decompression
- Bilateral decompression from a unilateral approach
Different Surgical Modalities
- Decompression with conventional laminectomy
- Bilateral decompression via the unilateral approach
- Decompression with fusion: Fusion has increased risks of blood loss, infection, longer hospital stays, and higher costs. Decompression alone is not inferior to fusion surgeries. A concomitant fusion should be considered for patients with spondylolisthesis, scoliosis, and lateral listhesis.
- Augmentation laminoplasty causes less surgical trauma.
- Endoscopic decompression: low risk of recurrence, preserve stability, minimal blood loss and complications
- Interspinous process devices: high dislocation, fracture of the spinous process, and low cost-effectiveness
- Decompression with Interlaminar stabilization
- Decompression with lumbar spinal process-splitting laminectomy: less postoperative pain.
- Minimally invasive tubular decompression: reduced trauma, rapid recovery, shorter operating time and lesser intraoperative blood loss, and a better satisfaction rate. ranked top for most outcomes for treating single-segment LSS.
- Microscopic decompression.
- Robot-assisted.
Helpful Armamentarium
- Machine learning and Artificial Intelligence.
- Surgical simulations.
- Intraoperative sonography to confirm restoration of the subarachnoid space.
- Intraoperative neuromonitoring has not been found to be reliable at predicting new neurologic deficits but is a useful adjunct to ease the surgeon when no intraoperative abnormalities are detected.
- Anti-fibrotic agents may prevent epidural fibrosis and adhesions.
- The 3D-printed artificial lamina may help in facilitating stability.
Enhancing Healthcare Team Outcomes
Laminectomy is among the most common procedures spinal surgeons perform to decompress the spinal canal in various conditions. Preoperative and postoperative patient care is crucial to improving outcomes of laminectomy. General practitioners, nurses, and pharmacists should advise the patient to change lifestyle, such as weight control and stop smoking. Making referrals to other professionals is essential when concomitant and associated pathologies could be present. All involved members of the interprofessional team need to communicate across interprofessional lines to achieve optimal outcomes. [Level 5]
Complete comprehensive preoperative planning requires assessment. It is essential to carefully document neurological status before surgery and develop correct and complete operative consent describing the magnitude, scope, and detailed complications of the surgery, as well as detailed alternatives considering nonoperative management. The nurse plays a role during the preoperative preparation of patients undergoing spine surgery. The nurse assists the clinician during the procedure and helps with the proper positioning of the patient. The nurse monitors the patient's vital signs before, during, and after the procedure. If there are any untoward changes in the patient's observations, the nurse should immediately alert the clinician and document the findings in the patient's medical records. The nurse should counsel patients appropriately about their care plans and ensure that the patient understands all components of valid consent. The best possible outcome for patients undergoing laminectomy could only be fostered through clear and efficient communication and collaboration among the interprofessional team members. [Level 5]
Relief of symptoms by bending forward is a reliable clinical variable in canal stenosis. Physical variables alone were not found to be predictors of a favorable postoperative outcome. A combination of clinical and radiological variables is of utmost importance. The relief of pain after epidural steroid injections may be a good prognostic indicator of surgical outcome. The neurological deficit and low comorbidity were good prognostic indicators for favorable outcomes. Increased signal intensity within the cord is a prognostic variable.
Multivariate analysis showed medical comorbidities, previous laminectomy, and accidental durotomy increased the risk of surgical complications. Independent risk factors for readmission were long operative time, previous spinal surgery, and extended hospital stays.
Multi-national Scandinavia study showed similar indications for decompression surgery but significant differences in advocating arthrodesis. Fusion did not improve effectiveness. There was no significant difference in the clinical outcome while comparing unilateral laminotomy with crossover, bilateral laminotomy, and spinous process osteotomy.
Outpatient Versus Inpatient Surgery
Outpatient surgery is comparable to inpatient surgery. Risk variables such as BMI >30 kg/m^2, age ≥55 years, functional dependency, medical comorbidities, and operative time >90 minutes have been linked to increased risk of complications in cohorts undergoing outpatient surgery.
Nursing, Allied Health, and Interprofessional Team Interventions
The nurse's role in the postoperative period should include finite management of intravenous fluids, foley catheter care until ambulating, administering antibiotics, pain control, wound/dressing care, encouraging patient ambulation, and advanced diet when appropriate.
Nursing, Allied Health, and Interprofessional Team Monitoring
Postoperative patient monitoring is essential for recognizing some early complications, especially CSF leakage from dural sac tears; it is crucial to evaluate the wound by looking for some suggestive signs, such as wound bulging or CSF sinus. Clinical signs of CSF leakage, such as headache and dizziness, should raise alert from possible complications.
The presence of erythema, increased pain, or swelling may raise the suspicion of wound infection.