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Thoracic ligamentous hypertrophy causing stenosis


Introduction

Thoracic stenosis can lead to compression of the spinal cord as a result of spinal degeneration, hypertrophy of the facet and ligamentum flavum, ossification of the ligamentum flavum, and diffuse idiopathic skeletal hyperostosis, among others. These changes may be the result of degenerative changes or microinstability at the location of the stenosis. This can be especially true for stenosis due to adjacent segment disease from a prior surgical fusion. Like cervical myelopathy, thoracic myelopathy can often present without diagnosis for years, leading to severe disability by the time a diagnosis is finally made. Symptoms may include gait imbalance, weakness, sensation loss, and even incontinence.

The management consideration becomes more complex when the stenosis is in the thoracolumbar junction. Surgical intervention may lead to destabilization when the stenosis is in thoracolumbar junction as the combination of decompression with the high mobility in this location can also lead to destabilization.

Example Case

  • Chief complaint: leg weakness

  • History of present illness: A 28-year-old female with a history of low back pain as well as some pain going down the backs of her legs. She says this resolved on its own. More recently, she reports having had a fall and then a couple of weeks later started having leg weakness. She also describes numbness in her feet. Since that time, she has only been able to walk 10 to 15 yards without having to sit down. She uses a single-point cane for short distances and a wheelchair for longer distances. She does not report any new bowel or bladder issues. She underwent imaging and this was concerning for thoracic stenosis ( Figs. 17.1 and 17.2 ).

    Fig. 17.1, Preoperative magnetic resonance images. (A) T2 sagittal and (B) T2 axial images demonstrating severe T9-T10 spinal canal stenosis and cord compression with cord edema/myelomalacia.

    Fig. 17.2, Preoperative computed tomography scans. (A) Sagittal and (B) axial images demonstrating severe T9-T10 spinal canal stenosis with calcification of the ligamentum flavum.

  • Medications: metformin

  • Allergies: no known drug allergies

  • Past medical and surgical history: diabetes, morbid obesity

  • Family history: noncontributory

  • Social history: retail, no smoking history, occasional alcohol

  • Physical examination: awake, alert, and oriented to person, place, and time; cranial nerves II–XII intact; bilateral deltoids/biceps/triceps 5/5; interossei 5/5; iliopsoas/knee flexion/knee extension 4+/5; dorsi and plantar flexion 4/5

  • Reflexes: 2+ in bilateral biceps/triceps/brachioradialis; 2+ in bilateral patella/ankle with positive clonus; right Babinski; negative Hoffman; sensation decreased in bilateral lower extremities

  • Richard J. Bransford, MD

  • Orthopaedic Surgery

  • University of Washington

  • Seattle, Washington, United States

  • Brett A. Freedman, MD

  • Sandra Hobson, MD

  • Orthopaedic Surgery

  • Mayo Clinic

  • Rochester, Minnesota, United States

  • Susana Núñez-Pereira, MD, PhD

  • Orthopaedic Surgery

  • Hospital Universitario Vall d’Hebron, Barcelona, Spain

  • Michael Y. Wang, MD

  • Yingda Li, MBBS

  • Neurosurgery

  • University of Miami

  • Miami, Florida, United States

Preoperative
Additional tests requested Upright scoliosis films

  • T-spine upright AP and lateral x-rays

  • MRI L-spine

  • MRI C-spine potentially

  • BMD scans

  • Hemoglobin A1C

  • T-spine x-rays

  • High resolution T-spine CT

  • Recheck MRI for edema or ligamentous injury

  • Pain drawing

  • Postvoid residual

  • Standing thoracic x-rays

  • Check lateral scout MRI to ensure correct level counting upwards from lumbosacral spine, and x-rays to ensure 12 ribs in total

  • Anesthesia evaluation

Surgical approach selected T8-10 laminectomy and T8-10 posterior fusion T9-10 laminectomy and fusion T9-10 laminectomy T9-10 laminectomy
Goal of surgery Spinal cord decompression, stabilization of spine Spinal cord decompression, stabilization of spine Spinal cord decompression Spinal cord decompression, prevent further neurological deterioration
Perioperative
Positioning Prone on Jackson table Prone on Jackson table, with Gardner-Wells tongs and 15 lb of traction Prone on Jackson table Prone on Jackson table
Surgical equipment

  • IOM (MEP/SSEP)

  • Fluoroscopy

  • IOM (MEP/SSEP/EMG)

  • O-arm

  • Surgical navigation

  • Surgical microscope

  • IOM

  • Fluoroscopy

  • IOM (MEP/ SSEP)

  • Fluoroscopy

  • Surgical microscope

Medications Maintain MAPs >85 Tranexamic acid, MAP >80 None Maintain MAPs >80, steroids
Anatomical considerations Dura, spinal cord Dura, spinal cord Ligamentum flavum Dura
Complications feared with approach chosen Durotomy, spinal cord injury, incorrect level Instability Persistent compression Durotomy Incorrect level, durotomy, cord injury, instability
Intraoperative
Anesthesia General General General General
Exposure T8-10 T9-10 T9-10 T9-10
Levels decompressed T8-10 T9-10 T9-10 T9-10
Levels fused T8-10 T9-10 None None
Surgical narrative Position prone on Jackson table with face pillow, fluoroscopy to assess level, midline posterior incision, subperiosteal dissection to expose T8-10 posterior elements to transverse processes, place mono-axial pedicle screws using anatomy from T8-10 bilaterally, x-ray to confirm location, drill to create laminectomy troughs from inferior T8 to top of T10, remove lamina and spinous process with care of dura, clean edges with Kerrison punches while protecting dura, place rods and secure, decorticate and place autograft from lamina from T8-10, layered closure with subfascial drain Preflip IOM, place Gardner-Wells tongs, position prone, incision planned with x-ray, dissect down through subcutaneous fat to level of deep dorsal fascia, fascia opened in line with incision, subperiosteal dissection preserving facet capsules, x-ray to confirm level, remove T9-10 facet capsule, expose associated lateral gutters for planned fusion bed, decorticate posterolateral gutter/lateral facet/lateral lamina, place T9-10 pedicle screws with anatomical landmarks and O-arm and surgical navigation, pedicle stimulation testing and intraoperative imaging, pack posterolateral gutters and facet joints with bone graft and demineralized bone matrix, T9-10 laminectomy with microscope using burs and Kerrison rongeurs, resect ligamentum flavum and medial facet capsules, confirm adequacy of decompression with a ball probe, place appropriately sized rods, place set screws and final tighten, layered closure with drain and incisional wound VAC Position prone, IONM, confirm level with fluoroscopy (count ribs preoperatively and check with fluoroscopy, if any doubt, count from sacrum), midline posterior incision, split muscles to visualize affected lamina and spinous process, x-ray to confirm level, remove spinous process, facetectomy with small chisel, high-speed drill to remove lamina to identify where lamina merges with facet, identify and remove ligamentum flavum and bone with Kerrison, protecting dura. If there are some adherences, small fragments not compressing might be left in situ decompress both sides to minimize spinal cord manipulation, further decompression to make sure cord is decompressed, layered closure with drain Position prone on Jackson with arms forward, level localization by counting up from sacrum or from AP fluoroscopic identification of 12th rib, midline incision, bilateral subperiosteal dissection, level confirmation with marker on pedicle, laminectomy to lamina-facet junction, Woodson elevator to free calcified ligamentum from dura, can leave portions adherent to dura floating if detached laterally, avoid downward pressure on thecal sac and have continuous monitoring, antibiotic irrigation, subfascial drain, layered closure
Complication avoidance Anatomical pedicle screws, leave superior T8 and inferior T10 lamina, when dissecting care of ossification of ligamentum flavum Preflip IOM, surgical navigation for pedicle screws, pedicle stimulation testing and intraoperative imaging, incisional wound VAC Decompress widely to provide better visualization and minimize spinal cord manipulation Level localization based on sacrum or 12th rib, dissect calcified ligament from dura, leave ligament in areas adherent, dural sealant if CSF leak sufficiently wide i.e. pedicle-to-pedicle decompression
Postoperative
Admission Floor Floor Floor Floor
Postoperative complications feared Epidural hematoma, medical complications Infection, adjacent-level disease CSF leak CSF leak, spinal cord injury, iatrogenic instability, failure to improve
Anticipated length of stay 3 days 2–3 days 2–3 days 2–3 days
Follow-up testing

  • CT T-spine prior to discharge

  • Upright T-spine x-rays prior to discharge, 3 months, 6 months, 1 year after surgery

  • T-spine upright AP and lateral x-rays prior to discharge, 3 months, 6 months after surgery

  • ESR/CRP while inpatient

  • CT T-spine 6 months after surgery

None Physical therapy
Bracing None None None None
Follow-up visits 3–4 weeks, 3 months, 6 months, 1 year after surgery 2 weeks, 3 months, 6 months after surgery 2 and 6 weeks and 6 and 12 months 2 and 8 weeks after surgery
AP , Anteroposterior; BMD , bone mineral density; BMP , bone morphogenic protein; CRP , C-reactive protein; CSF , cerebrospinal fluid; CT , computed tomography; EMG , electromyogram; ESR , erythrocyte sedimentation rate; IOM , intraoperative monitoring; MAP , mean arterial pressure; MEP , motor evoked potentials; MIS , minimally invasive surgery; MRI , magnetic resonance imaging; SSEP , somatosensory evoked potentials; VAC , vacuum assisted closure.

Differential diagnosis

  • ▪

    Thoracic myelopathy

  • ▪

    Transverse myelitis

  • ▪

    Multiple sclerosis

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