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Tethered cord


Introduction

Tethered cord syndrome (TCS) refers to the clinical condition produced by excessive tension of the spinal cord, with its caudal part anchored by inelastic structures that restrict its vertical movement. Inelastic structures include adipose filum terminale, tumor, myelomeningoceles, lipomyelomeningoceles, and scar formations. In the vast majority of cases, the spinal cord is tethered at the lumbosacral level. TCS results from the coexistence of anatomical and functional disturbances of the spinal cord. The degree of cord traction and the metabolic impairment of the spinal cord are the determining factors for the development and the severity of symptoms. The most consistent complaints are back and leg pain exacerbated by postural changes. Onset of clinical manifestations can occur early in life or during adulthood. Patients with tethering of the spinal cord can be divided into two groups depending on the presence or absence of spinal dysraphism. Prognosis and treatment of patients with dysraphism is similar to pediatric TCS. The presence of progressive symptoms or signs are indications for surgical treatment especially in patients with incontinence. In addition, some surgeons recommend surgery when signs of dysraphism are present. Around 86% of patients experience pain relief after operative treatment. In this chapter, we present the case of a young female patient with urinary retention, lower limb pain, and a history of previous closed neural tube defect.

Example case

  • Chief complaint: urinary retention, lower limb and back pain

  • History of present illness: This is a 48-year-old female patient with a history of spina bifida and a spinal mass who underwent lumbar surgery more than 15 years prior. She has been stable for many years with chronic but tolerable back pain. The patient was lost to follow-up and presented recently with new urinary retention and pain in her both lower extremities when active. She does not report any weakness. As part of her evaluation, the patient underwent a lumbar spine magnetic resonance image demonstrating a tethered cord and a large cystic intradural mass at the level of L3 ( Fig. 69.1 ).

    Fig. 69.1, Preoperative magnetic resonance imaging (MRI) of the lumbosacral spine. (A) Sagittal T2 MRI of the entire spine demonstrating a hyperintense cystic lesion occupying the L3 level and an apparent tethered cord with a low lying conus medullaris. The lesion is slightly heterogenous with a central hypointensity, sharply circumscribed, corresponding to an intradural adipose tissue. (B) Sagittal T1 with contrast and fat suppression demonstrating the lipoma as an isointense mass. (C) Sagittal T2 MRI of the lumbar spine demonstrating a tethered spinal cord attached to the lipoma at the L3 level. Degenerative disc changes at L4-L5 and L5-S1 are also present.

  • Medications: antidepressants

  • Allergies: no known drug allergies

  • Past medical and surgical history: as above

  • Family history: noncontributory

  • 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; 1+ in bilateral patella/ankle; no clonus or Babinski; sensation diminished in perianal region and both lower extremities

  • Carlos A. Bagley, MD

  • Neurosurgery

  • University of Texas Southwestern

  • Dallas, Texas, United States

  • Nicolas Dea, MD, MSc

  • Neurosurgery

  • Vancouver Spine Surgery Institute

  • Vancouver, Canada

  • Fernando Hakim, MD

  • Hospital Universitario Fundacion Santafe de Bogota

  • Bogota, Colombia

  • Jang Yoon, MD

  • Neurosurgery

  • University of Pennsylvania

  • Philadelphia, Pennsylvania, United States

Preoperative
Additional tests requested

  • Urology evaluation with urodynamic studies

  • Bilateral lower extremity EMG/NCS

  • Medicine evaluation

  • Urology evaluation with urodynamic studies

  • Compare previous MRI scans

  • MRI brain, C- and T-spine

  • CT L-spine

  • Urodynamic studies

  • Neurophysiological testing (EMG, NCS, SSEP)

  • Anesthesiology evaluation

  • MRI C- and T-spine

  • Standing L-spine x-rays with flexion-extension

  • Urology evaluation

  • Neurology evaluation

Surgical approach selected Revision L2-4 laminectomy and excision of intradural lipoma and release of tethered cord Revision laminectomy, spinal lipoma resection, spinal cord untethering Revision laminectomy, spinal lipoma resection, spinal cord untethering Revision laminectomy, removal of intradural extramedullary lesion, spinal cord untethering
Goal of surgery Spinal cord untethering, remove the mass, decompress neural elements Spinal cord untethering, remove the mass, decompress neural elements Spinal cord untethering, remove the mass Spinal cord untethering, cord decompression, diagnosis, removal of mass, complex wound closure
Perioperative
Positioning Prone on Jackson table Prone with pins Prone, no pins Prone in Wilson frame on flat Jackson table
Surgical equipment

  • IOM (MEP/SSEP/EMG)

  • Nerve stimulator

  • Surgical microscope

  • Laser

  • IOM (MEP/SSEP/EMG)

  • Laser

  • Dural substituteSurgical microscope

  • IOM (MEP/SSEP/EMG)

  • Surgical microscope

  • Ultrasound

  • Ultrasonic aspirator

  • IOM (MEP/SSEP/EMG)

  • Ultrasound

  • Nerve stimulator

  • Surgical microscope

Medications Steroids, pregabalin Steroids None None
Anatomical considerations Spinal cord, facet joints Spinal cord, conus, cauda equina nerve roots Cauda equina nerve roots Spinal cord, conus, cauda equina nerve roots
Complications feared with approach chosen Spinal cord injury, CSF leak, spinal instability Conus injury Nerve root injury, CSF leak Spinal cord injury, nerve root injury, retethering
Intraoperative
Anesthesia General General General General
Exposure L2-4 L2-5 L2-4 L1-4
Levels decompressed L2-4 L2-4 L2-4 L1-4
Levels fused None None None None
Surgical narrative Position prone, open previous incision from L2-4, expose remnant posterior elements as well as inferior portion of L1 and superior portion of L5, remove superficial elements from L2-L4 and partially L1 and L5 to find normal anatomy and dura using drill, define lateral edges of dural plane, widen laminectomy from L2 to 4 to obtain sufficient exposure, linear dural opening and tack dural edges using microscope, expose lipoma and normal spinal cord both rostral and caudal, shave down and remove as much lipoma as possible using laser and microdissector leaving a thin rim, use stimulator to identify any questionable neural vs. scar tissue, detether cord, watertight dural closure with Valsalva, irrigate wound, dural sealant to suture line, multilayer closure Position prone, obtain baseline SSEP/MEP, revision laminectomy from normal to abnormal, find normal dura, expose previous durotomy, midline durotomy, localize normal anatomy, find mass and dissect off of nerve roots, potential laser to remove lipoma with constant IOM, attempt neural tube closure with pial sutures, cut filum, duraplasty with suturable patch Position prone, fluoroscopy to localize level, midline incision, subperiosteal dissection, expose posterior elements, fluoroscopy to confirm level, scar tissue dissection under microscopic visualization, midline durotomy, ultrasound to make sure exposure is sufficient, tenting sutures, identify lipoma, debulk mass using ultrasonic aspirator, subtotal resection, cauda equina dissection under EMG monitoring, identify filum terminale, separate from surrounding cauda equina, suture placed through filum to aid in pathological examination, watertight dural closure, dural patch if necessary, fibrin sealant, layered closure Position prone, expose normal anatomy at L1 and bottom on L4, work around the scars to expose normal lamina, preserve posterior tension band and facet complexes, remove bottom of L1 and L4 to find normal dura, work toward the scar tissue, ultrasound to identify lesion, open dura from normal toward scar, tack dura up, dissect lesion away from spinal cord under microscope, try freeing dentate ligaments or scar if present to minimize tension on spinal cord, resect filum terminale after removal of lesion, stimulate cauda equina to confirm nerves are not resected, watertight dural closure with dural sealant, closure in layers
Complication avoidance Identify remnant posterior elements, find normal anatomy and dura cranial and caudal from previous opening, widen laminectomy to obtain sufficient exposure, leave tiny rim of lipoma, nerve stimulator Laminectomy from normal to abnormal, locate conus and nerve roots, laser lipoma removal Ultrasound to guide opening, aim for subtotal resection, cauda equina dissection under EMG monitoring, suture placed through filum to aid in pathological examination Expose to find normal anatomy, preserve posterior tension band and facet complexes, dissect dentate ligaments and scar to minimize tension, nerve stimulator to avoid injury to cauda equina, dural sealant
Postoperative
Admission Floor Floor ICU ICU
Postoperative complications feared CSF leak, urinary retention, urinary tract infection, wound infection, medical complication CSF leak, conus injury, retethering CSF leak, nerve injury Pseudomeningocele, CSF leak, retethering, instability, wound complications
Anticipated length of stay 4 days 2–5 days 2–3 days 3–5 days
Follow-up testing MRI L-spine within 2 days of surgery MRI L-spine 2-3 months after surgeryUrology follow-up None Lumbar x-rays including flexion-extension prior to discharge Physical therapy MRI L-spine 12 months after surgery
Bracing None None None None
Follow-up visits 6 weeks after surgery 2–3 months after surgery 2 weeks after surgery 2 weeks, 6 weeks, 3 months, 6 months, 12 months, 24 months after surgery
CSF , Cerebrospinal fluid; CT , computed tomography; EMG , electromyography; ICU , intensive care unit; IOM , intraoperative monitoring; MEP , motor evoked potential; MRI , magnetic resonance imaging; NCS , nerve conduction study; SSEP , somatosensory evoked potential.

Differential diagnosis

  • ▪

    Intramedullary tumor

  • ▪

    Intradural extramedullary tumors

  • ▪

    Multiple sclerosis

  • ▪

    Bone tumors (multiple myeloma)

  • ▪

    Lipoma

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