eMedicine Specialties > Neurosurgery > Neoplasm

Spinal Cord Tumors - Management of Intradural Intramedullary Neoplasms

Author: James S Harrop, MD, Associate Professor, Departments of Neurological and Orthopedic Surgery, Jefferson Medical College
Coauthor(s): Ashwini D Sharan, MD, Assistant Professor of Neurosurgery, Assistant Professor of Neurology, Thomas Jefferson University School of Medicine
Contributor Information and Disclosures

Updated: May 27, 2009

Introduction

Intradural or primary spinal cord tumors (neoplasms) are uncommon lesions and fortunately affect only a minority of the population. However, when lesions grow, they result in compression of the spinal cord, which can cause limb dysfunction, motor and sensation loss, and, possibly, lead to death. Spinal tumors are classified based on their anatomic location as related to the dura mater (lining around the spinal cord) and spinal cord (medullary) as epidural, intradural extramedullary, or intradural intramedullary. Primary spinal tumors are typically intradural in location, where extradural spinal tumors are typically due to metastatic disease.

This article focuses on the evaluation and management of intradural intramedullary spinal cord tumors. The typical histopathological types that account for 95% of these intramedullary neoplasms include astrocytomas, ependymomas, and hemangioblastomas. Spinal cord astrocytomas and ependymomas can be further classified as glial cell neoplasms.

History of the Procedure

In 1887, Sir Victor Horsley performed the first successful resection of an intradural neoplasm diagnosed by William Gower. This lesion was an intradural extramedullary tumor that compressed the spinal cord. However, the patient did not survive the intervention.  Due to limited operative techniques, the first successful removal of an intradural intramedullary tumor, performed by Eiselsberg-Renzi, did not occur until 1907.

In 1925, Charles Elsberg published the first large series of patients who underwent resections of primary spinal cord neoplasms. Unfortunately, again because of the limited operative techniques of this period, these patients endured significant surgical morbidity and mortality. However, subsequent advances in imaging, sterile operative techniques, microsurgical dissection, operating microscopy, and neurophysiologic monitoring have facilitated removal of these lesions with substantially improved clinical results.

Problem

Spinal cord parenchyma consists of both gray (neurons and supporting glial cells) and white matter (axonal) and tracts that transmit impulses between the brain and body. These tracts, or circuits, control posture, movement, sensation, and autonomic system function, including bowel, bladder, and sexual function.

Neurologic dysfunction develops as the spinal cord tumors enlarge and compress adjacent healthy neural tissue, disrupting these pathways. Upon further compression, patients can lose complete motor function and sensation below the lesion. In addition to weakness and sensory loss, patients may experience pain, particularly at night. This pain is believed to be related to disturbances in venous outflow by the tumor, causing engorgement and swelling of the spinal cord.

Frequency

Intramedullary spinal cord tumors account for approximately 2% of adult and 10% of pediatric central nervous system neoplasms. In adults, 85-90% of intramedullary tumors are the glial subtypes, astrocytoma or ependymoma. Ependymomas account for approximately 60-70% of all spinal cord tumors found in adults, while, in children, 55-65% of intramedullary spinal cord tumors are astrocytomas. Hemangioblastomas account for 5% of tumors, whereas paragangliomas, oligodendrogliomas, and gangliogliomas account for the remaining lesions.

Etiology

The pathogenesis of spinal neoplasms is unknown, but most arise from normal cell types in the region of the spinal cord in which they develop. A genetic predisposition is likely, given the higher incidence in certain familial or syndromic groups (neurofibromatosis). Astrocytomas and ependymomas are more common in patients with neurofibromatosis type 2, which is associated with an abnormality on chromosome 22. In addition, spinal hemangioblastomas can develop in 30% of patients with von Hippel-Lindau syndrome, which is associated with an abnormality on chromosome 3.

Pathophysiology

The spinal cord consists of numerous nerve bundles that descend from and ascend to the brain. Electrical impulses are carried and transmitted to facilitate movement and sensation. With intramedullary spinal cord tumors, compression and stretching of these fiber tracts results in loss of the motor and sensory function. As the tumors grow, the patient's neurologic function further deteriorates.

Presentation

Patients with intramedullary glial spinal cord tumors (ie, ependymomas, astrocytomas) typically present with back pain referred from the level of the lesion, sensory changes, or worsening function. The symptoms can be of a long duration, since these lesions tend to grow slowly and typically have a benign histopathology. Patients with low-grade astrocytomas tend to experience symptoms over a mean duration of 41 months. This is in contrast to patients with malignant astrocytomas, whose symptoms persist for a mean duration of only 4-7 months before diagnosis.

Tumor-specific characteristics

• Ependymomas
  • Mean age at presentation of 43 years
  • Slight female predominance
  • Pain localized to the spine (65%)
  • Pain worse at night or upon awakening
  • Dysesthetic pain (burning pain)
  • Long history of symptoms
  • Myxopapillary variant (mean age of presentation of 21 y; slight male predominance)
• Astrocytomas
  • Equal male and female prevalence
  • Pain localized to spine
  • Pain worse at night or upon awakening
  • Paresthesias (abnormal sensation)
• Hemangioblastomas
  • Onset of symptoms by the fourth decade of life, 80% symptomatic by age 40 years
  • Familial disorder (ie, von Hippel-Lindau syndrome) present in a third of patients
  • Decreased posterior column sensation
  • Back pain localized over lesion

Physical examination findings

• Motor weakness (late finding)
• Sensory
  • Decreased touch, pain, and/or temperature sensation
  • Hyperesthesias
  • Decreased proprioception (inability to localize limbs in space)
  • Abnormal sensation below the level of lesion
  • Abnormal sensation only at level of lesion (suspended level)
• Hyperreflexia
  • Hoffman sign for cervical lesions
  • Clonus
  • Extensor plantar response (Babinski sign)
• Spasticity
• Increased tone
• Muscle atrophy (late finding)

Indications

Intramedullary spinal cord neoplasms or tumors are typically histopathologically "benign" or slow growing. However, patients can have more aggressive neoplasms as well as morbidity due to the location of the lesion. Consequently, compared with similar intracranial neoplasms, patients may have a prolonged survival after diagnosis.

Optimal treatment options depend on the patient's clinical symptoms and neurologic finding. When and whether to treat these lesions as well as perform radiosurgery or surgical excision of lesions remains controversial. However, cures have been reported only after complete surgical resection. Therefore, patients with neurologic symptoms and confirmatory findings from imaging studies may benefit most from surgical excision, with the surgical goal of total gross resection of the lesion.

Relevant Anatomy

Arterial

Understanding the normal spinal cord vascular supply is essential to treating intramedullary spinal cord lesions; specifically because these vessels may have a variable and inconsistent distribution.

The great vessels (aorta, carotids) contribute arterial supply to the spinal cord via segmental arteries, which further branch into medullary and radicular arteries. The radicular artery provides extramedullary blood supply to the nerve root and dura; the medullary artery bifurcates into anterior and posterior divisions to form the spinal arteries. One anterior and 2 posterior spinal arteries then transverse the longitudinal axis of the spinal cord and provide the blood supply to the spinal cord. Neoplasms acquire their blood supply by leaching blood from these vessels.

Venous

The venous plexus of the spinal column, termed the Batson plexus, is unlike other venous systems in the body because the veins do not contain valves. Therefore, blood can have pathologic retrograde flow. This retrograde flow blood can back up and cause venous congestion. This can manifest as venous hypertension. Because oxygenated blood cannot pass through the spinal cord because of the congestion of outflow, patients present with progressive neurologic dysfunction.

Spinal cord

The spinal cord parenchyma consists of a central canal surrounded by an H-shaped gray matter region that contains neurons. Outer myelinated nerve tracts, termed white matter, surround the central gray matter. The central canal represents an embryologic remnant from neurulation of the neural plate and is lined with ependymal cells. Ependymomas arise from these cells and, therefore, are typically located centrally in the spinal cord parenchyma. In contrast, astrocytes support gray matter neurons and white matter axons. Neoplastic transformation of these supporting cells results in the development of astrocytomas and may occur almost anywhere within the cord.

Contraindications

Observation with serial imaging studies over a variable period is a treatment option for patients who pose a high surgical risk, who are elderly, and/or who only have minimal neurologic signs. Patients in whom pathology tissue shows a malignant neoplasm may be best treated with radiotherapy because they are expected to have an accelerated deterioration and complete surgical resection is not possible.

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