Indications
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Intradural meningioma causing pain or neurologic deficits
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Intradural meningioma causing mass effect on the spinal cord or associated nerve roots in the absence of clinical symptoms; surgery should be considered for these lesions because of the slowly progressive growth pattern and likelihood of neurologic deterioration in the future
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Intradural extramedullary lesion of unclear etiology and the need for tissue diagnosis
Contraindications
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Small, asymptomatic or incidentally noted lesions can be followed with serial magnetic resonance imaging (MRI) for evidence of tumor growth before surgical resection.
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Severely debilitated patients or patients with significant medical comorbidities or short life expectancies should be considered for palliative treatment or radiation therapy.
Planning and positioning
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A detailed history and physical examination is important in the initial work-up of a spinal intradural meningioma. Information about the onset, duration, and distribution of symptoms and neurologic deficits helps guide surgical management.
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After initial clinical assessment, MRI is crucial for diagnosis and operative planning. Meningiomas typically appear isointense to hypointense on T1-weighted imaging, appear hyperintense on T2 sequences, and homogeneously enhance after contrast agent administration. Important MRI characteristics that distinguish meningiomas from other spinal intradural lesions include displacement of the spinal cord away from the lesion, widening of the subarachnoid space adjacent to the mass, and the presence of a “dural tail.” X-ray and computed tomography (CT) scan may also be necessary to determine the need for instrumented fixation after surgical resection of the lesion. If the meningioma involves vascular structures, such as the vertebral artery in the upper cervical region or at the level of the foramen magnum, spinal angiography or noninvasive vascular imaging should be considered to determine the vascular relationship to the tumor and to assess for collateral blood flow.
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Motor evoked potential (MEP) monitoring should be used to assess for spinal cord injury during resection of intradural meningiomas. Needle electrodes should be placed in the end muscles before final prone positioning in the operating room. Propofol and fentanyl are commonly used anesthetic agents that do not affect MEP monitoring.
Figure 98-1:
MRI is an important diagnostic tool in the surgical management of spinal intradural meningiomas. Sagittal ( left ) and axial ( right ) T1-weighted MRI after gadolinium contrast agent administration. Note the homogeneously enhancing extraaxial mass at the T8 level involving the left side of the spinal canal and causing significant spinal cord compression.
Figure 98-2:
For the lesion shown in Figure 98-1 , a dorsal approach is recommended, although ventral or ventrolateral tumors in the cervical or thoracic spine may be approached anteriorly. For the dorsal approach, the patient is positioned prone, either in three-point Mayfield head fixation on two chest rolls for cervical spine lesions or on a Wilson frame or chest rolls without head fixation for thoracic and lumbar tumors. All dependent surfaces (e.g., knees, elbows) should be padded to avoid pressure-related tissue necrosis or peripheral nerve injury.
Planning and positioning
- •
A detailed history and physical examination is important in the initial work-up of a spinal intradural meningioma. Information about the onset, duration, and distribution of symptoms and neurologic deficits helps guide surgical management.
- •
After initial clinical assessment, MRI is crucial for diagnosis and operative planning. Meningiomas typically appear isointense to hypointense on T1-weighted imaging, appear hyperintense on T2 sequences, and homogeneously enhance after contrast agent administration. Important MRI characteristics that distinguish meningiomas from other spinal intradural lesions include displacement of the spinal cord away from the lesion, widening of the subarachnoid space adjacent to the mass, and the presence of a “dural tail.” X-ray and computed tomography (CT) scan may also be necessary to determine the need for instrumented fixation after surgical resection of the lesion. If the meningioma involves vascular structures, such as the vertebral artery in the upper cervical region or at the level of the foramen magnum, spinal angiography or noninvasive vascular imaging should be considered to determine the vascular relationship to the tumor and to assess for collateral blood flow.
- •
Motor evoked potential (MEP) monitoring should be used to assess for spinal cord injury during resection of intradural meningiomas. Needle electrodes should be placed in the end muscles before final prone positioning in the operating room. Propofol and fentanyl are commonly used anesthetic agents that do not affect MEP monitoring.
