Surgical Technique for Resection of Intradural Tumors

Overview

Primary tumors of the spinal cord are relatively rare, comprising 2% to 4% of all primary central nervous system tumors. Spinal tumors are generally identified by location and can be put into three groups: extradural, intradural-extramedullary, and intramedullary . The surgical approach to intradural neoplasms depends primarily on two factors: location of the mass and whether the mass is intramedullary or extramedullary. An overview of the most common adult intramedullary and extramedullary tumors is provided in Table 66-1 and Table 66-2 , respectively.

Table 66-1

Primary Intramedullary Tumors

Tumor	Prevalence *	Location	Treatment	Notes
Ependymoma	~50% to 60%	Cervical > thoracic > lumbosacral (except myxopapillary subtype)	Gross total resection if possible; radiation and/or chemotherapy if unresectable	Myxopapillary subtype typically arises in the conus or filum and is extramedullary.
Astrocytoma	~25% to 35%	Cervical > thoracic	Gross total resection rarely possible; biopsy to guide treatment and for prognosis; chemotherapy and/or radiation	World Health Organization grade is most important prognosticator.
Hemangioblastoma	Rare	Cervical > thoracic	Gross total resection if possible; radiation and/or chemotherapy if unresectable	10% to 30% of patients with spinal hemangioblastoma have von Hippel-Lindau syndrome.
Ganglioglioma	Rare	Cervical > thoracic	Gross total resection if possible; radiation and chemotherapy data lacking	Prognosis is excellent if gross total resection is achieved.
Primary CNS lymphoma	Rare	Typically diffuse disease	Biopsy only; surgical debulking not indicated; chemotherapy mainstay of treatment	Prognosis is poor.
Germinoma	Rare	Insufficient data	Biopsy only; typically sensitive to chemotherapy and radiation	Image entire neuroaxis to rule out disease elsewhere.
Melanoma	Rare	Insufficient data	Gross total resection if possible (rare); radiation and/or chemotherapy if unresectable	Prognosis is poor.

CNS, central nervous system.

From Chamberlain MC, Tredway TL: Adult primary intradural spinal cord tumors: a review. Curr Neurol Neurosci Rep 11:320–328, 2011.

* Percent of intramedullary tumors.

Table 66-2

Primary Intradural, Extramedullary Tumors

Tumor	Prevalence *	Location	Treatment	Notes
Meningioma	~50%	Thoracic (~80%) ≫ cervical > lumbosacral	Surgical if symptomatic; may be observed with serial imaging; radiotherapy an option for incomplete resection or recurrence	Gross total excision may be curative; 80% occur in females
Schwannoma	~25%	Cervical > cauda equina > thoracic > conus	Surgical if symptomatic; may be observed with serial imaging	Increased incidence in NF2; almost uniformly histologically benign
Neurofibroma	~25%		Surgical if symptomatic; usually observed with serial imaging	Increased incidence in NF1; plexiform subtype carries poor prognosis (may progress to MPNST), but otherwise benign
MPNST	Rare		Gross total resection if possible (rare); radiation and/or chemotherapy if unresectable	Associated with NF1 and poor prognosis

MPNST, malignant peripheral nerve sheath tumor; NF1, neurofibromatosis type 1; NF2, neurofibromatosis type 2.

From Chamberlain MC, Tredway TL: Adult primary intradural spinal cord tumors: a review. Curr Neurol Neurosci Rep 11:320–328, 2011.

* Percent of intradural-extramedullary tumors.

Spinal magnetic resonance imaging (MRI) and computed tomographic (CT) myelogram are helpful to distinguish between intramedullary and extramedullary tumors ( Fig. 66-1 ). Intramedullary lesions typically can be resected with posterior or posterolateral approaches, whereas intradural-extramedullary tumors may require anterior, anterolateral, lateral, posterolateral, or posterior approaches.

In this chapter, we will discuss the common open approach for intradural-extramedullary and intramedullary tumor resection. In the recent literature, different authors describe minimally invasive surgical (MIS) approaches to access these types of tumors. However, unless the surgeon is very familiar and comfortable with these approaches, we recommend the more traditional open approach.

Indications and Contraindications

Indications

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Neurologic deficit
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Histologic diagnosis of lesion
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Recurrence of lesion

Relative Contraindications

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No neurologic deficit
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Blood dyscrasias
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Multiple comorbidities
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Poor prognosis (life expectancy <3 to 6 months)

Surgical Technique

Equipment

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Mayfield calvarial fixation for posterior approaches (cervical or upper thoracic)
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Radiolucent operating table
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Fluoroscopy
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High-magnification and high-illumination microscope
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Self-retaining retractor system (cerebellar retractor, modular retractor, or tubular dilator retractor for MIS approach)
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Electrocautery (monopolar and bipolar)
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Hemostatic agents (bone wax, Gelfoam, Surgifoam, and/or FloSeal)
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Various sizes of Kerrison and pituitary rongeurs and microcurettes
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High-speed drill with matchstick or diamond burr
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Various sizes of sutures
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Neurophysiologic monitoring (somatosensory-evoked and motor-evoked potentials [SSEPs and MEPs], electromyelogram [EMG], and anal sphincter monitoring)
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High-dose steroids at start of case or preoperatively
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Prophylactic antibiotics

Patient Positioning

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Prone for posterior or posterolateral approaches with the patient taped down to prevent movement with operating bed rotation
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Lateral for lateral or anterolateral approaches
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Supine for anterior approach
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Adequate padding of all bony prominences and pressure points