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Thoracic intradural extramedullary lesion


Introduction

Intradural extramedullary thoracic spinal cord tumors are rare entities that cause thoracic myelopathy and occasionally radiculopathy. These tumors occur in 5 to 10 per 100,000 persons. The two most common intradural extramedullary pathological diagnoses are schwannomas and meningiomas. Schwannomas are usually solitary lesions and multiple schwannomas occur in patients with neurofibromatosis type 2. Ninety percent of spinal meningiomas are located in the thoracic spine and 95% of the cases are World Health Organization (WHO) grade I. Less common tumors include neurofibroma and hemangiopericytoma. While schwannomas typically arise from a thoracic sensory rootlet, meningiomas have a dural attachment and are often located ventral to the spinal cord. The surgical removal of these lesions often requires working in a tight corridor, as the diameter of the spinal canal in the thoracic levels is the smaller compared with the lumbar and cervical levels. Complete removal of a ventrolateral or ventral lesion may require removal of the rib head or pedicle for adequate exposure without cord manipulation. On the other hand, most of the spinal schwannomas and meningiomas are noninfiltrative and often can be completely resected. In the present chapter, we describe a case of a patient with a benign tumor involving the intradural extramedullary compartment of the thoracic spine.

Example case

  • Chief complaint: difficulty walking

  • History of present illness: This 44-year-old male with a history of back pain and buttock pain. This has been going on for approximately 8 months. Patient also developed gait difficulties, as well as numbness in his bilateral lower extremities. He reports some urinary urgency but denies any incontinence. This has progressively worsened over the last few months. He underwent imaging and this revealed a thoracic intradural extramedullary lesion ( Fig. 58.1 ).

    Fig. 58.1, Preoperative magnetic resonance images. (A) Sagittal T1 with contrast, (B) sagittal T2, (C) T1 axial with contrast images demonstrating a homogeneously enhancing extraaxial mass filling the spinal canal at the level of T10 measuring 1.5 × 1.8 × 2.2 cm, causing severe mass effect on the spinal cord, displacing/flattening it posteriorly and to the right. Associated T2 hyperintensity within the cord is consistent with compressive myelopathy.

  • Medications: fluoxetine, indomethacin

  • Allergies: no known drug allergies

  • Past medical and surgical history: none

  • Family history: none

  • Social history: none

  • Physical examination: awake, alert, and oriented to person, place, and time; cranial nerves II–XII intact; bilateral deltoids/triceps/biceps 5/5; interossei 5/5; iliopsoas/knee flexion/knee extension/dorsi, and plantar flexion 5/5

  • Reflexes: 2+ in bilateral biceps/triceps/brachioradialis with negative Hoffman; 3+ in bilateral patella/ankle; 2 beats of clonus; diminished sensation intact to light touch in bilateral lower extremities

  • Eyal Itshayek, MD

  • Neurosurgery

  • Hadassah Medical Center

  • Jerusalem, Israel

  • Alugolu Rajesh, MD

  • Neurosurgery

  • Nizam’s Institute of Medical Sciences

  • Punjagutta, Hyderabad, India

  • Justin S. Smith, MD, PhD

  • Neurosurgery

  • University of Virginia

  • Charlottesville, Virginia, United States

  • Anand Veeravagu, MD

  • Neurosurgery

  • Stanford University

  • Palo Alto, California, United States

Preoperative
Additional tests requested

  • CT T-spine

  • Anesthesia evaluation

  • MRI brain and complete spine

  • MRI spine tractography

  • Anesthesiology evaluation

  • MRI brain and complete spine

  • CT T-spine

  • Long cassette x-ray for rib counting for intraoperative localization

  • CT chest/abdomen/pelvis

  • CT T-spine

Surgical approach selected T10 right hemilaminectomy, T10 right pediculectomy, excision of intradural extramedullary tumor and T9-T11 fusion T9-11 laminectomy and resection of the lesion T9-11 instrumented arthrodesis with T9-11 laminectomy, T10 pedicle and rib head resection T9-11 laminectomy for resection of intradural mass with possible transpedicular or costotransversectomy
Goal of surgery Gross total resection, preservation of neurological function Resection of lesion, decompression of spinal cord Resection of lesion, diagnosis, decompression of spinal cord Resect mass, decompress spinal cord, stabilize thoracic spine
Perioperative
Positioning Prone on Jackson table Prone Prone on Jackson table Prone on Jackson table, no pins
Surgical equipment

  • IOM

  • Fluoroscopy

  • Surgical microscope

  • Ultrasonic aspirator

  • IOM (MEP)

  • Fluoroscopy

  • Ultrasonic bone scalpel

  • Surgical microscope

  • Ultrasonic aspirator

  • IOM (MEP/SSEP)

  • Fluoroscopy

  • Surgical microscope

  • Micro instruments

  • Dural sealant

  • IOM (SSEP/MEP)

  • Fluoroscopy

  • Surgical microscope

  • Surgical navigation

  • Ultrasound

  • Ultrasonic aspirator

Medications MAP >80 Steroids None Steroids
Anatomical considerations Lamina, transverse process, pedicle Spinal cord, nerve roots, dentate ligament Spinal cord, confirmation of spinal level Appropriate level, central canal, spinal cord
Complications feared with approach chosen Spinal cord injury Spinal cord injury Neurological deficit Spinal cord injury
Intraoperative
Anesthesia General General General General
Exposure T9-11 T9-11 T9-11 T9-11
Levels decompressed T10 T9-11 T9-11 T9-11
Levels fused T9-11 None T9-11 None
Surgical narrative Preflip IOM baseline, position prone onto Jackson table, localize surgical level with fluoroscopy in AP position counting ribs, midline skin incision, subperiosteal dissection exposing bilateral spinous processes/laminas/transverse processes, place left T9-T11 and right T9 and T11 pedicle screws with titanium rod on left, right T11 hemilaminectomy and the ascending and descending facets, complete hemilaminectomy with Kerrison, right T9-10 and T10-11 facetectomy, remove T10 pedicle to level of vertebral body, identify T9-10 nerve roots, open dura with paramidline incision under microscopic visualization right T11 nerve root, retract dura with Prolene, identify tumor, cut dentate ligament and nerve root if needed, sharply dissect arachnoid defining plane surrounding tumor, identify planes, coagulate tumor capsule, open capsule and internally decompress with ultrasonic aspirator, dissect tumor capsule from arachnoid plane from spinal cord, coagulate insertion area on dura and resect any remnants from dura, watertight dural closure with TachoSil patch, connect right T9-T11 pedicle screws with titanium rod, layered closure, lumbar drain if dura unable to be closed Position prone, skin incision planning using x-ray, midline skin incision one level above and one level lower than incision, subperiosteal dissection of paraspinal muscles until facet joints, laminectomy one level above and below lesion and more on right side, dural opening starting at cranial aspect, dura tacked up, lesion identified and arachnoid peeled over the while length until capsule is removed under microscope, intratumoral decompression using ultrasonic aspirator after biopsy, remaining capsule dissected off and making to spare adherent nerve roots after adequate decompression, small rootlet entering tumor is sacrificed, watertight dural closure, layered closure with drain Position prone on Jackson table, fluoroscopy to mark incision from T9 to 11, expose T9-11 and confirmation of levels with fluoroscopy once exposed, place T9-11 pedicle screws excluding right T10, T9-11 laminectomies, removal of right T10 pedicle and rib head, open dura under microscopic visualization off to right side, tack up dural edges, use micro instruments to dissect and remove tumor, likely release dentate ligaments to facilitate tumor removal, goal is gross total removal, close dura, dural sealant, places rods spanning T9-11 along with graft for arthrodesis, two subfascial drains layered wound closure Obtain prepositioning IOM, position prone, AP fluoro for localizing level, expose and two-level laminectomy centered on the mass, intraoperative ultrasound to ensure dural exposure is sufficient, dural opening on side of tumor origin under microscope, tumor biopsy and intraoperative pathology, resect tumor with ultrasonic aspirator, dissect tumor off surface of spinal cord to resect completely, resect dural attachment and bipolar depending on location, close with Gore-tex suture and fibrin flue
Complication avoidance Preflip IOM baseline, localize surgical level with fluoroscopy in AP position counting ribs, cut dentate ligament and nerve root if needed, internally debulk tumor, lumbar drain if dura unable to be closed More laminectomy on right side, peel arachnoid over entire length of lesion, internal debulking of tumor before removing off nerve roots Removing pedicle and rib head to allow more lateral access and less spinal cord manipulation, paramedian dural opening eccentric to side of tumor, release dentate ligaments to decrease cord manipulation, dural sealant with closure Prepositioning IOM, AP fluoroscopy for localization, intraoperative ultrasound to assess exposure, transpedicular or costotranversectomy if needed for exposing, Gore-tex suture
Postoperative
Admission ICU Floor ICU Floor
Postoperative complications feared Spinal cord injury, CSF leak Neurological deficit, CSF leak Hematoma, CSF leak Worsening thoracic myelopathy, CSF leak
Anticipated length of stay 3 days 1–2 days 4 days 4 days
Follow-up testing MRI T-spine 3 months after surgery None if gross total resection achieved

  • MRI T-spine 6 weeks, 1 year, 3 years after surgery

  • Spine x-rays 6 weeks, 6 months, 1 year, 2 years after surgery

MRI T-spine 1 month, 6 months, 12 months, and annually after surgery
Bracing None None None None
Follow-up visits 6 weeks, 3 months after surgery 4 weeks after surgery 10–14 days, 6 weeks, 1 year, 2 years after surgery 2 weeks, 1 month, 3 months, 6 months after surgery
AP , Anteroposterior; APP , advanced practice provider; BAERs , brainstem auditory evoked responses; CSF , cerebrospinal fluid; CT , computed tomography; DEXA , dual-energy x-ray absorptiometry; IOM , intraoperative monitoring; MAP , mean arterial pressure; MEP , motor evoked potentials; MRI , magnetic resonance imaging; PLL , posterior longitudinal ligament; PSIS , posterior superior iliac spine; SSEP , somatosensory evoked potential.

Differential diagnosis

  • ▪

    Meningioma

  • ▪

    Schwannoma

  • ▪

    Other spinal cord tumor

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