Surgical Approaches to Intramedullary and Extramedullary Spinal Cord Tumors : A Surgeon's Guide

Overview

Spinal cord tumors are abnormal growths within or surrounding the spinal cord. These tumors can be benign (non-cancerous) or malignant (cancerous) and may arise from different cells within the spinal cord or its surrounding structures. Spinal cord tumors are classified into three main categories:

1. Intramedullary Tumors: These originate within the spinal cord itself, typically arising from glial cells. Common examples include ependymomas and astrocytomas.
2. Intradural-Extramedullary Tumors: These tumors grow outside the spinal cord but within the dural membrane. Meningiomas and schwannomas are typical examples.
3. Extradural Tumors: These originate outside the dura mater and may be metastatic lesions or primary bone tumors such as osteosarcomas.

Indications for Spinal Cord Tumor Surgery

Surgery is generally indicated in the following scenarios:

• Progressive Neurological Deficits: Worsening motor or sensory function due to tumor compression.
• Intractable Pain: Persistent, severe pain not manageable with conservative treatments.
• Radiographic Evidence of Spinal Instability: Tumors causing vertebral collapse or instability.
• Spinal Cord Compression: Imaging studies showing significant compression of the spinal cord.
• Malignancy: Tumors suspected or confirmed to be malignant, requiring resection for histological diagnosis or debulking.

Preoperative Evaluation

Preoperative evaluation is crucial to ensure the patient's safety and optimize surgical outcomes. Key components include:

1. Imaging Studies:
   • MRI with Contrast: The gold standard for diagnosing spinal cord tumors. It provides detailed visualization of the tumor's size, location, and relationship to surrounding structures.
   • CT Scan: Useful for assessing bony involvement and surgical planning.
   • PET Scan: In cases of suspected metastasis, PET scans can help identify the primary tumor and other metastatic sites.
2. Neurological Assessment:
   • Motor and Sensory Function: Detailed examination to document baseline deficits.
   • Reflexes: Assessment of deep tendon reflexes, Babinski sign, and other relevant reflexes.
   • Bowel and Bladder Function: Evaluating autonomic function is critical, especially in lower spinal cord tumors.
3. Laboratory Tests:
   • Routine Blood Work: Complete blood count, electrolytes, coagulation profile.
   • Tumor Markers: If metastasis is suspected, tumor markers can provide clues to the primary source.
4. Consultations:
   • Oncology: For malignant tumors, multidisciplinary discussion with oncologists can help plan adjuvant therapies.
   • Anesthesia: Preoperative assessment by an anesthesiologist, particularly in patients with comorbidities.

Contraindications

While surgery is a primary treatment modality, it is contraindicated in certain scenarios:

• Poor General Health: Patients with severe comorbidities that preclude anesthesia or surgery.
• Unresectable Tumors: Tumors involving critical structures where resection would cause significant morbidity.
• Systemic Metastatic Disease: In cases where the patient has widespread metastatic disease and surgery would not improve quality of life.
• Patient Refusal: Informed consent is critical, and surgery should not proceed without it.

Surgical Techniques and Steps

Surgical resection of spinal cord tumors can be challenging due to the delicate nature of the spinal cord and its surrounding structures. The surgical approach depends on the tumor's location, size, and type.

1. Positioning:
   • Patients are typically positioned prone for posterior approaches. A lateral position may be used for anterolateral tumors.
   • Careful padding and alignment are essential to avoid pressure sores and nerve injuries.
2. Surgical Approaches:
   • Laminectomy: The most common approach, involving the removal of the posterior vertebral arch to access the spinal cord.
   • Costotransversectomy: Used for tumors involving the vertebral body or lateral spinal cord.
   • Anterior Approaches: Employed for tumors located anterior to the spinal cord, often requiring thoracotomy or retroperitoneal approaches.
3. Tumor Resection:
   • Intramedullary Tumors: Microsurgical techniques are used to enter the spinal cord and remove the tumor, often requiring intraoperative neurophysiological monitoring.
   • Intradural-Extramedullary Tumors: The dura is opened, and the tumor is resected using microdissection techniques.
   • Extradural Tumors: These may require en bloc resection with stabilization if there is significant bony involvement.
4. Intraoperative Monitoring:
   • Neurophysiological Monitoring: Somatosensory evoked potentials (SSEPs) and motor evoked potentials (MEPs) are used to monitor spinal cord function during surgery, reducing the risk of neurological injury.
5. Closure:
   • The dura is closed watertight, often with a dural patch if necessary. The wound is closed in layers, and a drain may be placed if significant dissection has occurred.

Postoperative Care

Postoperative care is critical in managing potential complications and promoting recovery. Key aspects include:

1. Neurological Monitoring:
   • Frequent assessments of motor and sensory function, as well as bowel and bladder control.
   • Monitoring for signs of spinal cord edema or hematoma, which may necessitate urgent reoperation.
2. Pain Management:
   • Multimodal analgesia, including opioids, NSAIDs, and muscle relaxants.
   • Early mobilization and physical therapy to reduce stiffness and promote recovery.
3. Infection Prevention:
   • Prophylactic antibiotics, typically continued for 24 hours postoperatively.
   • Wound care to monitor for signs of infection.
4. DVT Prophylaxis:
   • Mechanical prophylaxis (e.g., compression stockings) and pharmacological agents (e.g., low molecular weight heparin) as appropriate.
5. Rehabilitation:
   • Early physical and occupational therapy to restore function.
   • Long-term rehabilitation for patients with significant neurological deficits.

Possible Complications

Complications from spinal cord tumor surgery can be severe and include:

• Neurological Deficits: Worsening of preoperative deficits or new deficits due to surgical manipulation or spinal cord ischemia.
• Cerebrospinal Fluid (CSF) Leak: Due to dura mater injury, potentially leading to pseudomeningocele or meningitis.
• Infection: Superficial or deep wound infections, including osteomyelitis or discitis.
• Spinal Instability: Especially after extensive bony resection, potentially requiring stabilization with instrumentation.
• Hemorrhage: Intraoperative or postoperative bleeding leading to hematoma formation and possible spinal cord compression.
• Recurrence: Particularly in cases of incomplete resection or malignant tumors.

Prognosis and Outcome

The prognosis for patients undergoing spinal cord tumor surgery depends on various factors:

• Tumor Type: Benign tumors generally have a better prognosis, with higher rates of complete resection and lower recurrence rates.
• Extent of Resection: Gross total resection is associated with better outcomes, particularly in benign tumors.
• Preoperative Neurological Status: Patients with less severe preoperative deficits tend to have better postoperative recovery.
• Malignancy: Malignant tumors, especially metastatic lesions, often have a poorer prognosis, with surgery aimed at palliation rather than cure.

Alternative Treatment Options

While surgery remains the cornerstone of spinal cord tumor management, alternative treatments may be considered in specific cases:

• Radiation Therapy: Used as primary treatment for inoperable tumors, adjuvant therapy post-surgery, or palliative care in metastatic disease.
• Chemotherapy: Generally limited to malignant tumors, particularly those that are chemosensitive, such as certain lymphomas.
• Observation: In asymptomatic, slow-growing tumors, especially in elderly or frail patients, observation with regular MRI may be appropriate.

Average Cost of Surgery

The cost of spinal cord tumor surgery varies widely based on factors such as the complexity of the case, the surgeon's expertise, and the geographical location. In the United States, the cost can range from $50,000 to $150,000 or more, including preoperative imaging, surgery, hospital stay, and postoperative care. Internationally, costs may be lower, but the quality of care and access to advanced technology may vary.

Recent Advances in Spinal Cord Tumor Surgery

Recent advances in spinal cord tumor surgery have improved patient outcomes and reduced complications:

• Intraoperative MRI: Allows real-time imaging during surgery, helping to achieve more complete tumor resections.
• Minimally Invasive Techniques: Smaller incisions and less tissue disruption lead to quicker recovery and reduced postoperative pain.
• Robotic-Assisted Surgery: Provides greater precision and control, particularly in complex cases.
• Genetic and Molecular Profiling: Advances in tumor biology have led to more targeted therapies and personalized treatment plans.

Conclusion

Spinal cord tumor surgery is a highly specialized and complex procedure that requires meticulous planning, precise surgical technique, and comprehensive postoperative care. While the risks are significant, advances in technology and surgical methods have improved outcomes for many patients. Surgeons must stay abreast of the latest developments to provide the best possible care for their patients.