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Cervical myelopathy


Introduction

Myelopathy denotes any neurological deficit related to a pathology of the spinal cord. A spinal cord injury (SCI) can be produced by diverse etiologies such as trauma, ischemia, neoplasms, inflammatory processes, and infection. However, degenerative cervical myelopathy (DCM) is the most common cause of spinal cord dysfunction. Degenerative myelopathy may result from spondylosis, disc herniation, or facet arthropathy, as well as ligamentous hypertrophy, calcification, or ossification. DCM accounts for 54% of all the nontraumatic SCI in the United States. This condition mainly affects aging people and is usually diagnosed during the fifth decade of life. C5-C6 is the most commonly involved level regardless of gender and age. The pathogenesis of neurological impairment hinges on the direct injury to neurons and glial cells, either from static or dynamic mechanical insults. The spinocerebellar and corticospinal tracts are usually affected first. Onset of symptoms is usually insidious, and initial complaints are frequently gait disturbances and fine motor deficits. To establish a reliable correlation between the severity of symptomatology and the degree of radiographic compression is challenging. Most of the abnormalities that contribute to the development of DCM can be demonstrated with a magnetic resonance image (MRI), and therefore an MRI should be routinely performed if cervical myelopathy is suspected. Surgery is the standard treatment for DCM. Cervical decompression halts disease progression and improves neurological outcomes, functional status, and quality of life. Besides decompression of spinal cord, surgery should restore cervical alignment and address instability if present. The ideal approach to attain the aforementioned is still a matter of debate. Several factors impact the surgical strategy, such as the localization of the compression (anterior or posterior), levels affected, and the need to preserve cervical lordosis. Anterior approaches include discectomy and fusion and/or corpectomy, whereas common posterior techniques include laminectomy/laminoplasty and fusion. In this chapter, we present the case of a 68-year-old man presenting with gait disturbances/instability and hand atrophy with suspected cervical myleopathy.

Example Case

  • Chief complaint: instability

  • History of present illness: This is a 68-year-old man with a history of hand atrophy and gait instability for several weeks. He initially attributed these symptoms to his lumbar spine. He does have a history of prior lumbar laminectomy. The patient stated that he did have some difficulty with dexterity and balance and even suffered recurrent falls. He had some difficulty with urinary urgency, but he attributed this to his history of prostate cancer. Magnetic resonance image (MRI) and computed tomography (CT) of the cervical spine showed significant degenerative spinal canal stenosis with severe ventral compression of the spinal cord ( Figs. 20.1 and 20.2 ).

    Fig. 20.1, Preoperative magnetic resonance image (MRI) of the cervical spine. (A) T2 sagittal and (B) axial images of the cervical spine demonstrating a severe cervical degenerative spinal stenosis. Severe anterior spinal cord compression is evident from C4 to C6 levels, where compression is markedly worse at the C6 level. There is thickening of the anterior and posterior longitudinal ligaments and ossification of the anterior longitudinal ligament from C3 to C6. A decrease of the intervertebral space between C5 and C6 is noted, and there is anterior fusion between the fourth and fifth cervical vertebrae. Cervical kyphosis of the cervical spine is apparent.

    Fig. 20.2, Preoperative computed tomography (CT) of the cervical spine. (A) Sagittal and (B) axial images demonstrating a kyphotic deformity of the cervical spine and severe degenerative changes, including the fusion of C4 and C5 vertebrae, complete collapse of the anterior intervertebral space between C5 and C6, ossification of the anterior longitudinal ligament, and osteophyte formation.

  • Medications: ramipril

  • Allergies: no known drug allergies.

  • Past medical and surgical history: prostatic cancer, hypertension

  • Family history: noncontributory

  • Social history: engineer, no smoking, no alcohol

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

  • Reflexes: 2+ in bilateral biceps/triceps/brachioradialis with negative Hoffman; 2+ in bilateral patella/ankle; no clonus or Babinski; sensation intact to light touch

  • Richard Allen, MD, PhD

  • Jakub Sikora, MD

  • Orthopaedic Surgery

  • University of California at San Diego

  • San Diego, California, United States

  • Richard J. Bransford, MD

  • Orthopaedic Surgery

  • University of Washington

  • Seattle, Washington, United States

  • Juan Fernando Ramon, MD

  • Neurosurgery

  • University Hospital Fundacion Santa Fe de Bogata

  • Bogota, Columbia

  • Timothy F. Witham, MD

  • Neurosurgery

  • Johns Hopkins

  • Baltimore, Maryland, United States

Preoperative
Additional tests requested

  • Confirm no other source of pathology

  • Swallow evaluation

  • C-spine Flex/Ext X-rays

  • AP/lateral/flexion/extension C-spine x-rays

  • Medicine evaluation

  • C-spine Flex/Ext X-rays

  • AP/lateral/flexion/extension C-spine x-rays

  • Medicine evaluation

  • C-spine Flex/Ext X-rays

  • DEXA

  • Standing scoliosis x-rays/EOS imaging

  • Calcium, vitamin D, PTH, testosterone serum levels

  • Medicine evaluation

  • C-spine Flex/Ext X-rays

Surgical approach selected

  • Stage 1: C4-5 anterior cervical corpectomy, C6-7 ACDF, C3-6 plating fusion

  • Stage 2: C5-C7 laminectomy and C2-T2 posterior fusion

  • Stage 1: C4-5 corpectomy and C6-7 ACDF

  • Stage 2: C2-T2 posterior fusion and C3-6 laminectomy

C3-4 corpectomy

  • Stage 1: C4-5 corpectomy, C3-6 reconstruction, C3-6 plating

  • Stage 2: C2-T2 fixation and fusion, possible C6-7 laminectomy

Goal of surgery Decompress spinal cord, restore alignment, stabilize spine Decompress spinal cord, restore lordosis and physiological alignment, stabilize spine Decompress spinal cord, restore lordosis, stabilize spine Decompress spinal cord, restoration of anatomical alignment, stabilization
Perioperative
Positioning

  • Stage 1: supine with Gardner-Wells tongs

  • Stage 2: prone, with Gardner-Wells tongs

  • Stage 1: supine on Jackson flat top with Gardner-Wells tongs

  • Stage 2: prone on Jackson flip frame with Mayfield pins

Supine, no pins

  • Stage 1: supine with 10 pounds traction

  • Stage 2: prone with pins

Surgical equipment Fluoroscopy

  • IOM (MEP/SSEP/EMG)

  • Fluoroscopy

  • Surgical microscope

  • Fluoroscopy

  • O-arm

  • Stage 1: IOM, fluoroscopy

  • Stage 2: IOM, fluoroscopy, bone scalpel

Medications Tranexamic acid MAPs >85 None Vitamin D/calcium supplements if needed, PTH analog if needed, MAP >85
Anatomical considerations Vertebral arteries, PLL, thecal sac Esophagus, sympathetic plexus, trachea, carotid artery, recurrent laryngeal nerve, vertebral arteries Esophagus, larynx, vascular structures, uncincate process, PLL Vertebral arteries, spinal cord, cervical nerve roots
Complications feared with approach chosen Dysphagia Inadequate decompression, misalignment Vascular injury, esophageal injury, recurrent laryngeal nerve injury Spinal instability, inadequate decompression
Intraoperative
Anesthesia General General General General
Exposure

  • Stage 1: C3-7

  • Stage 2: C2-T2

  • Stage 1: C3-7

  • Stage 2: C2-T2

C3-6

  • Stage 1: C3-7

  • Stage 2: C2-T2

Levels decompressed

  • Stage 1: C3-6

  • Stage 2: C5-7

  • Stage 1: C3-6

  • Stage 2: C3-6

C3-4

  • Stage 1: C3-6

  • Stage 2: C6-7

Levels fused

  • Stage 1: C3-7

  • Stage 2: C2-T2

  • Stage 1: C3-7

  • Stage 2: C2-T2

C3-6

  • Stage 1: C3-6

  • Stage 2: C2-T2

Surgical narrative

  • Stage 1: Position supine with Gardner-Wells tongs, modified left oblique neck incision through skin and platysma, modified Smith-Robinson approach releasing hyoid, develop subplatysmal flaps down through superficial and deep cervical fascia, subperiosteally dissect anterior cervical spine, confirm location with spinal needle, remove anterior osteophytes and flatten, C6-7 ACDF with microscope, place Caspar pins and retractor, annuolotomy and removal of disc, parallel the endplates with matchstick bur and avoid taking structural end plate, bur back to uncovertebral joints and posteriorly down to PLL, foraminotomies at C6-7, trial graft sizes and place structural allograft, move Caspar pins proximally, take annulotomy to C3 and perform C5-6 and C4-5 discectomy, begin corpectomy using matchstick and bur down to PLL on right then on left, resect freed vertebral body with Leksell, remove underlying PLL, identify entire dural sac, insert cage with allograft/autograft/demineralized bone matrix, place anterior cervical plate from C3-7, final AP and lateral x-rays, layered closure

  • Stage 1: position supine with 10–15 lb of traction in lordotic position, left-sided transverse incision in Langer’s line centered about C5 body, dissection to longus colli with wide exposure and gentle pressure, place retractor and Caspar pins with one in C3 and one into C6 vertebral body, bring in microscope, C3-4 and C5-6 discectomy, create trough with drill at uncovertebral joints along C4 and C5 body on left and right, remove as much of the vertebral bodies as possible and save bone, remove posterior bone with up-angled curettes/Kerrison/pituitary rongeurs, dissect through PLL to see dura and ensure decompression, place cage from C3 to C6 with optimized lordosis and cage filled with autograft, remove Caspar pins, C6-7 discectomy through PLL, place lordotic corticocancellous allograft after decompression, place plate spanning from C3-7, close incision over drain

Position supine, head slightly extended, neutral, lateral x-ray to check level, right lateral horizontal incision, platysma dissection, identify border of sternocleidomastoid, open anterior cervical fascia, blunt finger dissection, palpate carotid artery, identify and retract larynx/thyroid/esophagus, put retractor on longus colli base, dissect levels as needed, place pins at C3 and C6, distract, C3-4 corpectomy, C4-5 discectomy, identify PLL and uncinate process, prepare end plates for implant, put PEEK implant with bone chips, x-ray to check position, screw fixation with plate, x-ray to confirm location and hardware, layered closure with drain

  • Stage 1: position supine on Mayfield horseshoe, position supine with 10 lb traction, postposition IOM, right-sided vertical incision along anterior border of sternocleidomastoid, localizing x-ray, Caspar pins at C3 and C6 for distraction, place self-retaining retractors, C3-4 and C5-6 discectomies, C4-5 corpectomies with drill to PLL, open and resect PLL to decompress cord and C4-6 nerve roots bilaterally, size and fill cage, place cage, remove weight from traction, remove distraction pins, place plate, layered closure with drain, x-ray

  • Stage 2 (same day): position prone with Gardner-Wells tongs, midline incision C2-T2, subperiosteal dissection, C5-7 laminectomy, C2 pedicle screws, C4-6 lateral mass crews aiming up and out approximately 15 degrees, place pedicle screws at C7-T2, instrument from C3-T2, decorticate, final tighten, set screws, place autograft and allograft, layered closure with Marcaine in subcutaneous space

  • Stage 2 (same day): replace tongs with Mayfield pins, flip into prone position, optimize lordosis of spine, subperiosteal exposure from C2 lateral mass to T2 transverse processes, place C2 pars/C3-6 lateral mass (Magerl technique)/T1-2 pedicle screws, laminectomy troughs from C3-6 at junction of lamina and lateral mass, remove lamina and ensure decompression, place lordotic rods from C2 pars to T2 pedicle screws and secure, decorticate from C2-T2 and place autograft from laminectomy mixed with demineralized bone matrix for fusion, layered closure with subfascial drain, take to ICU intubated

  • Stage 2 (next day): position prone with Mayfield pins, postposition IOM, expose C2-T2, C6-7 en bloc laminectomy with ultrasonic bone scalpel, drill pilot holes, drill screw holes, decorticate bone, place instrumentation and rods, x-ray, layered closure with drain

Complication avoidance Two-staged approach, flatten anterior cervical spine to prevent dysphagia, perform discectomy prior to corpectomy to get appropriate interbody, do not remove structural end plate during discectomy, C7 pedicle screws Traction during anterior approach, troughs along uncovertebral joints, dissect through PLL, optimize lordosis with anterior cage, two-staged approach, Magerl technique for cervical lateral mass screws Anterior cervical approach with distraction, maintain PLL Two-staged approach dependent on degree of decompression between stages, traction to help with alignment, open PLL, MRI between stages
Postoperative
Admission ICU ICU ICU Intermediate care
Postoperative complications feared Dysphagia, pseudoarthrosis, wound complications, instrument failure Dysphagia, airway issues Dysphagia, cervical hematoma, vascular injury, esophageal injury Dysphagia, C5 palsy, CSF leak, instrument failure, pseudoarthrosis, esophageal injury
Anticipated length of stay 3–4 days 4–5 days 3–4 days
Follow-up testing C-spine x-rays 6 weeks, 3 months, 6 months, 1 year after surgery

  • CT C-T spine within 24 hours of surgery

  • C-spine x-rays prior to discharge, 3 months, 6 months, 12 months after surgery

C-spine x-ray 1 month after surgery

  • MRI C-spine after stage 1

  • CT C-spine within 48 hours after stage 2

  • C-spine x-rays 6 weeks, 3 months, 6 months, 12 months after surgery

Bracing Aspen brace for 10 weeks, soft collar all day for 2 weeks, soft collar at night only for 2 weeks Miami J for 10–12 weeks Hard collar for 4 weeks Collar dependent on bone quality
Follow-up visits 2 weeks, 6 weeks, 3 months, 6 months, 1 year after surgery 4 weeks, 3 months, 6 months, 12 months after surgery 1 month after surgery 2 weeks, 6 weeks,3 months, 6 months, 12 months after surgery
ACDF , Anterior cervical decompression and fusion; CT , computed tomography; DEXA , dual-energy x-ray absorptiometry; EMG , electromyography; ICU , intensive care unit; IOM , intraoperative monitoring; MAP , mean arterial pressure; MEP , motor evoked potentials; MRI , magnetic resonance imaging; PEEK , polyetheretherketone; PLL , posterior longitudinal ligament; PTH , parathyroid hormone level; SSEP , somatosensory evoked potentials.

Differential diagnosis

  • ▪

    Cervical stenosis

  • ▪

    Intramedullary spinal cord tumor

  • ▪

    Transverse myelitis

  • ▪

    Syringomyelia

  • ▪

    Peripheral nerve entrapment

  • ▪

    Normal pressure hydrocephalus

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