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Thoracic intramedullary lesions


Introduction

The thoracic spine, which includes attachments to the rib cage, is one of the most challenging regions for surgical interventions. Intramedullary cord thoracic lesions are not common, where intramedullary spinal cord tumors (IMSCTs) only account for 20% to 30% of the primary spinal cord neoplasms and approximately 2% to 4% of all central nervous system (CNS) lesions. In respect to primary tumors, gliomas are the most frequent neoplasms that involve the cord and account for up to 80% of these cases. Ependymomas represent the highest occurrence in adults (50%–60%), followed by astrocytomas and hemangioblastoma, respectively. IMSCTs can be found at any level of the spinal cord; however, IMSCTs show a predilection for the cervical (33%) and the thoracic (26%) levels. The thoracic spinal cord is a high-complexity network of eloquent tissue that produces severe neurological deficit and comorbidities when partially or completely disconnected from the rest of the CNS. Thus optimal treatment must find a balance between extent of resection and adjuvant therapies while minimizing neurological deficits. In this chapter, we present a case of a 24-year-old woman presenting with lower limb weakness and back pain with a thoracic IMSCT.

Example case

  • Chief complaint: lower limb weakness

  • History of present illness: This is a 24-year-old healthy female who presented with a 3-month history of lower limb weakness and back pain. In addition, she reported numbness and tingling in both inner thighs for the past 2 weeks with difficulty climbing up stairs and occasional difficulty voiding. The patient was thoroughly evaluated including magnetic resonance image (MRI) of the thoracic spine that showed a T11-T12 well-defined intramedullary mass with heterogenous enhancement ( Fig. 52.1 ).

    Fig. 52.1, Preoperative magnetic resonance image (MRI) of the thoracic spine. (A) Sagittal and axial T1 with contrast image demonstrating an intraaxial heterogeneous mass with well-demarcated borders at the level of T11-T12. The mass is centrally located and is exerting significant mass effect on the spinal cord. (B) Sagittal T2 image demonstrating a heterogenous mass causing significant radial elongation of the spinal cord. The lesion measures approximately 4 cm in craniocaudal length. No significant cord edema or syrinx is noted.

  • Medications: none

  • Allergies: no known drug allergies

  • Past medical and surgical history: none

  • Family history: no history of malignancies

  • 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 3/5; dorsi, and plantar flexion 4/5

  • Reflexes: 2+ in bilateral biceps/triceps/brachioradialis with negative Hoffman; 3+ in bilateral patella/ankle; with bilateral positive Babinski; sensation diffusely decreased in left leg

  • Diego F Gómez MD MSc.

  • Neurosurgery

  • Fundación Santafe de Bogotá

  • Bogota, Colombia

  • George I. Jallo, MD

  • Neurosurgery

  • Johns Hopkins All Children’s

  • Tampa, Florida, United States

  • Allan D. Levi, MD, PhD

  • Meng Huang, MD

  • Neurosurgery

  • University of Miami

  • Miami, Florida, United States

Sheng-Fu Lo, MD Neurosurgery Johns Hopkins Baltimore, Maryland, United States
Preoperative
Additional tests requested MRI brain and complete spine EMG/NCS/SSEP

  • MRI brain and complete spine

  • Neurology evaluation

  • Oncology evaluation

  • CT chest/abdomen/pelvis CT

  • Lumbar spine MRI

  • Upright AP/lateral flexion-extension x-rays

MRI brain and complete spine MRI T-spine with CISS and DTI
Surgical approach selected T11–12 laminoplasty and intramedullary tumor resection T11–12 laminectomy possible laminoplasty and intramedullary tumor resection T11–12 laminoplasty and intramedullary tumor resection T11-T12 laminoplasty for en bloc resection of intramedullary tumor
Goal of surgery Tumor resection, diagnosis, spinal cord decompression Radical resection with preservation of neurological function Complete tumor resection Diagnosis, complete tumor resection with preservation of neurological function
Perioperative
Positioning Prone, no pins Prone Prone on Jackson table Prone on Jackson table
Surgical equipment

  • IOM (MEP/SSEP)

  • Fluoroscopy

  • Ultrasonic bone cutter

  • Ultrasound

  • IOM (MEP/SSEP)

  • Fluoroscopy

  • Ultrasound

  • Surgical microscope

  • Ultrasonic aspirator

  • IOM (MEP/SSEP)

  • Ultrasonic bone scalpel

  • Ultrasound

  • Surgical microscope

  • Ultrasonic aspirator

  • Craniofacial mini plates

  • Dural substitute

  • Fibrin glue

IOM (MEP/SSEP, D-wave) Ultrasonic bone scalpel Ultrasound Surgical microscope Nerve stimulator
Medications Steroids Steroids Steroids, MAP > 85 Steroids, MAP > 80
Anatomical considerations Spinal cord Spinal cord (midline dorsal median sulcus) Dorsal columns, corticospinal tracts, midline dorsal raphe Dorsal columns, corticospinal tracts, nontumor perforators from anterior spinal artery
Complications feared with approach chosen Spinal cord injury Injury to corticospinal tract and dorsal columns CSF leak, pseudomeningocele Injury to corticospinal tract, anterior spinal artery injury
Intraoperative
Anesthesia General General General General
Exposure T11–12 T11–12 T11–12 T11–12
Levels decompressed T11–12 T11–12 None T11–12
Levels fused None None None None
Surgical narrative Position prone, fluoroscopy to localize level, posterior midline incision, subperiosteal dissection exposing posterior elements, two-level laminoplasty using ultrasonic bone cutter after fluoroscopy, midline dural opening and tenting sutures, ultrasound to locate tumor and guide midline myelotomy, identify tumor and send for pathology, complete gross tumor removal if planes are identifiable with no SSEP/MEP changes, watertight dural closure with fibrin sealant, laminoplasty with titanium plates, layered closure with no drain Position prone, baseline IOM, x-ray to confirm appropriate levels, two- to three-level laminectomy or laminoplasty, ultrasound to confirm sufficient tumor exposure, open dura and visualize tumor, midline myelotomy to identify tumor, investigate to see if there is a tumor plane/capsule, attempt en bloc, obtain frozen pathology to see if pathology consistent with planes, work inside-out if no planes and debulk as much as possible, resection guided by MEP and SSEP, watertight dura closure, multilayer closure with laminoplasty if available Position prone on Jackson table, fluoroscopy localization, standard bilateral en bloc laminectomy with ultrasonic bone scalpel spanning level of tumor, ultrasound to confirm tumor location, microscope and dural opening with tenting sutures, identification of midline raphe, perform myelotomy with microdissection of tumor/cord interface with microsurgical instruments, frozen section, internal debulking of tumor with ultrasonic aspirator and fold tumor onto itself with gross total resection if not too adherent, watertight closure with 5-0 prolene/dural substitute/fibrin glue, reconstruction of lamina with craniofacial mini plates, layered closure with subfascial drain to gravity after 6 hours of suctioning Position prone on Jackson table, lateral x-ray to localize levels, baseline IOM, subperiosteal dissection from T11–12 while avoiding facet joint violations, laminoplasty with bone scalpel, intraoperative ultrasound to confirm exposure and tumor anatomy, place rostral and caudal epidural leads for D-wave monitoring, open dura and tent dura up with stitches, visually identify median sulcus with microscope by identifying dorsal medullary veins entering into the sulcus and translucent pia from tumor expansion, antidromic SSEP stimulation for dorsal column mapping to help identify sulcus, dissect tumor from spinal cord, identify rostral and caudal tumor ends and dissect ventral surface, minimize traction on spinal cord and electrocautery, remove tumor en bloc and protect subarachnoid spaces with cottonoids, repeat ultrasound to evaluate resection
Complication avoidance Laminoplasty, ultrasound to confirm opening and guide myelotomy, resection guided by planes and SSEP/MEP Ultrasound to confirm exposure and tumor location, inspect for tumor planes, attempt en bloc, work inside-out if no planes, resection guided by MEP/SSEP, possible laminoplasty En-bloc laminectomy with bone scalpel, ultrasound to localize tumor, identify midline raphe, internal debulking and folding in tumor, laminoplasty Laminoplasty while avoiding facet joint violation, intraoperative ultrasound to confirm exposure and tumor anatomy, D-wave monitoring, identify median sulcus with entry of dorsal medullary veins, posterior column mapping, minimize traction on spinal cord and electrocautery, en bloc tumor removal
Postoperative
Admission ICU ICU ICU ICU
Postoperative complications feared Motor deficit, sensory deficit CSF leak, motor deficit, sensory deficit CSF leak, pseudomeningocele Motor deficit, spinal cord stroke
Anticipated length of stay 2 days 3–4 days 3–4 days 3 days
Follow-up testing MRI T-spine within 48 hours after surgery Oncology evaluation MRI T-spine within 48 hours after surgery None MRI T-spine within 48 hours after surgery
Bracing None None None None
Follow-up visits 2 weeks after surgery

  • 10–14 days after surgery

  • Oncology evaluation

  • 2 weeks after surgery with nurse visit, 6 weeks with AP/lateral x-rays, 12 weeks/6 months/12 months MRI, followed by yearly MRI

  • Neuro oncology evaluation

  • Radiation oncology evaluation

2 weeks after surgery
AP , Anteroposterior; CISS , constructive interference in steady state; CT , computed tomography; DTI , diffusion tensor imaging; EMG , electromyography; ICU , intensive care unit; IOM , intraoperative monitoring; MAP, mean arterial pressure; MEP , motor evoked potentials; MRI , magnetic resonance imaging; NCS , nerve conduction study; SSEP , somatosensory evoked potential.

Differential diagnosis and actual diagnosis

  • ▪

    Glial tumor

  • ▪

    Spinal cord infection (abscess)

  • ▪

    Spinal cord infarction

  • ▪

    Multiple sclerosis (demyelination)

  • ▪

    Transverse myelitis

  • ▪

    Syrinx associated to Chiari malformation

  • ▪

    Spinal cord hemorrhage

  • ▪

    Tuberculoma

  • ▪

    Sarcoidosis

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