19: Resection of Intradural Intramedullary or Extramedullary Spinal Tumors

Published on 23/04/2015 by admin

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Procedure 19 Resection of Intradural Intramedullary or Extramedullary Spinal Tumors

John Christos Styliaras, Ashwini Sharan, John Birknes, John K. Ratliff, James S. Harrop

image

Indications

image Spinal cord compression can manifest as

• Weakness (in either upper or lower extremities, or both)
• Loss of bowel and bladder function
• Sensory loss (to light touch or pinprick)
• Incoordination of hands or gait

image Symptomatic neuronal compression, manifesting as radiculopathy

image Progressive growth of lesion on serial imaging

image Persistent pain or radiculopathy

image Spinal deformity resulting from remodeling of osseous elements

Indications Pitfalls

• Presence of concurrent neural axis lesions

Examination/Imaging

image Physical examination

• Spinal cord compression—myelopathy
• Radicular signs or symptoms
• Dermatologic findings in neurocutaneous disorders (e.g., neurofibromatosis)

image Plain films/computed tomography (CT) scan

• Typically nondiagnostic
• Bone erosion or remodeling of osseous elements (scalloping) resulting from prolonged presence of the lesion may be seen, but not often.
• May use CT scan to diagnose bony versus soft tissue cord compression

image Magnetic resonance imaging (MRI) with gadolinium

• Study of choice, because it provides more information about the lesion itself
• Differentiates type of intradural lesion
♦ Extramedullary—extrinsic to the spinal cord

• Meningioma—dural based. On T1- and T2-weighted images, it appears as a homogenous hypointense lesion compared with the cord, while on contrast-enhanced MRI, it enhances homogenously. In addition, many times it is calcified.
• Nerve sheath tumor (schwannoma and neurofibroma): The tumor is a dumbbell-shaped lesion that has a separate plane, is extrinsic to the spinal cord, and follows the nerve through the neural foramina (Figure 19-1, A). Coronal Images (Figure 19-1, B) illustrate the path of nerve sheath tumor exiting the foramen around the pedicle. On T1-weighted images, it is isointense to the cord, while on T2 images, it appears heterogenous and hyperintense. On contrast-enhanced MRI, it often appears with an irregular margin and ring-shaped enhancement.
♦ Intramedullary—located within spinal cord parenchyma (Figure 19-2)

• Expansion of the spinal cord
• Associated with intraparenchymal cyst or syrinx
• Primary glial neoplasms (e.g., ependymoma) predominate. On T1-weighted images, they appear isointense to the cord, while on T2-weighted images, they are hyperintense. On contrast-enhanced MRI, these lesions present with a well-defined margin and homogenous enhancement.

image image

FIGURE 19-1, A-B

image

FIGURE 19-2

Treatment Options

• Maximal tumor resection: Favorable outcomes postoperatively on intramedullary tumors are based on the histopathology of the tumor, total resection, and neurologic status preoperatively. In extramedullary tumors, postoperative neurologic recovery is very favorable in the vast majority of cases.

• Serial observation with imaging and clinical assessment is an option for intradural spinal cord tumor management in neurologically intact patients.

• Radiation therapy is a secondary treatment option or an adjuvant therapy in malignant or rapidly recurrent intramedullary spinal tumors (although optimum management in such cases remains controversial).

Surgical Anatomy

image Spinal column defines boundaries of the spinal canal. These boundaries are

• Anterior—vertebral body
• Lateral—pedicles
• Posterior—laminae and spinous processes

image Levels of the spinal column are

• Cervical—7 vertebrae
• Thoracic—12 vertebrae
• Lumbar—5 vertebrae

image Spinal meninges or coverings of the spinal cord

• Dura mater
♦ Thick fibrous layer
♦ Separated from osseous region by a space containing epidural veins, adipose, and fibrous tissue
• Arachnoid
♦ Delicate layer in between the dura and pia mater, containing the subarachnoid space
♦ The subarachnoid space is filled with cerebrospinal fluid and extends down to S2
• Pia mater
♦ Thin layer on the surface of the spinal cord
♦ Contacts the spinal cord and is adherent to blood vessels entering the spinal cord

image Spinal cord

• Approximately 45 cm in length
• Thirty-one pairs of spinal nerves arise from the spinal cord: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal.
• Conus medullaris: terminal end of the spinal cord (ends at level L1-2)
• Filum terminalis: fibrous band that continues distally and attaches to the dorsum of the first coccygeal vertebrae
• Spinal cord: highly organized, somatotopically arranged tissue composed of two functionally and anatomically distinct regions
♦ Gray matter—central portion; consists of neuronal cell bodies and supporting structures

• Axial plane—central bridge of gray matter connecting each side such that, in an axial section, it resembles the letter H
• Ventral portion—anterior horn motor cells
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