51-year-old woman with cervical myelopathy, posterior longitudinal ligament ossification
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A 51-year-old woman with no past medical history and on no medications presented to the office with a several-month history of left arm numbness, weakness in the bilateral lower extremities and gait instability.
On physical examination, the patient ambulated with a wide-based gait and had mild limitation in cervical spine range of motion, particularly extension. Sensory and motor testing revealed full strength and sensation in the bilateral upper and lower extremities throughout. Examination of reflexes demonstrated 3+ reflexes (hyperreflexia) in the bilateral biceps, triceps, patellar and Achilles tendons, as well as the presence of a Hoffman sign bilaterally.
Radiographs were obtained, including four views of the cervical spine (Figure 1). Anterior posterior, lateral, flexion and extension views demonstrated mild diffuse spondylotic changes throughout the cervical spine and mild retrolisthesis of C5 on C6 and C6 on C7, without instability. Advanced imaging in the form of a CT scan (Figure 2), as well as an MRI (Figure 3), was subsequently obtained. Axial and sagittal views of the CT scan revealed severe central stenosis at C5/6 and moderate central stenosis at C6/7 secondary to ossification of the posterior longitudinal ligament (OPLL) primarily behind the C6 vertebra. The T2-weighted axial and sagittal MRI views further demonstrated severe spinal cord compression with a cord signal abnormality at C5/6 in the left hemicord, as well as moderate bilateral foraminal narrowing at C5/6 and moderate right foraminal narrowing at C6/7.
Source: Yong H. Kim, MD; Stephane Owusu-Sarpong, MD
What are the best next steps in management of this patient?
See answer below.
Anterior cervical corpectomy with resection of OPLL and circumferential fusion
After a thorough discussion with the patient regarding the natural history of cervical myelopathy, the decision was made to proceed with surgery.
Surgical technique
Anterior portion: A left-sided Smith-Robinson approach of the cervical spine was performed through a transverse incision down to the C5/6 and C6/7 disc spaces. A spinal needle was placed into the C5/6 disc space and intraoperative fluoroscopy confirmed the correct level. After placement of self-retaining retractors, a standard annulotomy and complete discectomy were performed at C5/6 and C6/7, including resection of the posterior osteophytes and release of the PLL. Attention was then turned to resection of the OPLL. Partial corpectomy of C6 was initially attempted, with removal of the proximal half of the C6 vertebral body with a rongeur. The OPLL was noted to extend beyond the resected half of the C6 vertebral body, so the decision was made to do a full corpectomy of C6. Following resection of the C6 vertebral body, the OPLL was encountered and spanned the caudal aspect of the C5/6 disc level to the cephalad aspect of the C6/7 disc level. A plane was developed between the OPLL and the underlying dura, with no significant adhesions between these structures. The entire bulk of the OPLL was resected with a combination of Kerrison (DTR Medical) and pituitary rongeurs, leaving no fragments behind. The underlying dura was noted to be pulsating and healthy appearing.
A Pyramesh cage (Medtronic) was sized to fit the defect, packed with local autologous bone graft obtained from the corpectomy and gently impacted between C5 and C7. There was excellent compression fit of the cage onto the C5 and C7 vertebral bodies. An anterior variable-locking plate and four screws spanning from C5 to C7 were applied over the cage and intraoperative fluoroscopy confirmed appropriate placement. Standard closure was performed to conclude the anterior portion of the operation.
Posterior portion: After repositioning the patient prone, a standard midline exposure was carried out down to the spinous processes and lamina-facet junctions of C5 to C7. Deep self-retaining retractors were placed, and intraoperative fluoroscopy confirmed the operative levels. The starting points for the bilateral C5-C7 lateral mass screws were drilled using a standard variable-depth drill guide, followed by tapping to the appropriate length. The C5/6 and C6/7 facet joints were decorticated bilaterally and subsequently packed with morselized bone graft.
We placed 3.5-mm lateral mass screws of appropriate length in the prepared holes at C5, C6 and C7 bilaterally. Finally, 3.5-mm titanium rods of appropriate length were bent to fit C5 to C7 bilaterally. Endcaps were placed within all screws and fully tightened. Intraoperative fluoroscopy confirmed appropriate hardware placement and alignment. The remainder of the bone graft was placed laterally, and a standard layered closure was performed. The patient was awoken, extubated uneventfully and transferred to the recovery room. Postoperatively, she was neurologically intact.
Rehabilitation
The patient worked with physical therapy twice daily during her inpatient stay and her pain was controlled with oral analgesia (Tylenol [Johnson & Johnson] and oxycodone). Her postoperative course was uncomplicated, and she was discharged home on postoperative day 3.
At her 2-week postoperative visit, she reported 50% improvement in her left arm numbness, as well as improved ambulation and steadiness on her feet. Sensation and strength were intact and full throughout. Her wounds were healing well, and her posterior sutures were removed uneventfully. Radiographs of her cervical spine were obtained, which demonstrated stable appearance of her hardware. She will follow up in 4 weeks for clinical and radiographic evaluation.
Discussion
OPLL is a relatively uncommon but important cause of cervical myelopathy. Geographic location and ethnicity affect its incidence, with the highest prevalence reported in East Asian countries and particularly in Japanese patients, with a prevalence ranging from 1.9% to 4.3%. The PLL originates at the axis (C2) and extends distally to the sacrum, functioning primarily as a restraint to hyperflexion of the spinal column. The normal histologic features of the PLL include flat fibroblasts without any cartilaginous elements. In pathologic OPLL, fibroblast-like chondrocytes and osteoblasts proliferate in conjunction with overexpression of bone morphogenic proteins, resulting in neovascularization of the ligament, cartilaginous proliferation and hyalinoid degeneration and ossification. OPLL can be characterized by four subtypes: localized, segmental, continuous or mixed, based on the extent of the retrovertebral disease.
Surgical management is the mainstay of treatment and has been shown to improve clinical outcomes and halt the progression of myelopathy for patients with moderate to severe myelopathy secondary to OPLL. The goal of surgery is to decompress the neural elements either by expansion of the spinal canal (allowing the cord to “float back”) or by direct resection or thinning of the offending lesion, while preserving alignment and stability of the cervical spine. This can be achieved with anterior, posterior or combined approaches. Anterior approaches offer direct decompression of the OPLL but can be associated with a higher rate of cerebrospinal fluid leak, whereas posterior approaches are less technically demanding but have been associated with higher rates of OPLL progression and higher rates of C5 nerve palsy.
In our patient, a combined approach was undertaken given the severe localized OPLL behind the C6 vertebral body, necessitating complete C6 corpectomy and circumferential stabilization and fusion. The offending lesion was removed in entirety, alignment was preserved and, by going posterior, stability was maintained.
Key points:
- CT scan should be obtained for preoperative planning in cervical myelopathy cases.
- Surgery is the treatment of choice for myelopathy to halt progression and prevent further neurological decline.
- Combined approaches should be considered for severe localized OPLL.
- References:
- Ha Y, et al. World Neurosurg. 2016;doi:10.1016/j.wneu.2016.02.054.
- Head J, et al. Neurospine. 2019;doi:10.14245/ns.1938222.111.
- Kawaguchi Y, et al. J Orthop Sci. 2014;doi:10.1007/s00776-014-0577-4.
- Matsunaga S, et al. Spine (Phila Pa 1976). 2012;doi:10.1097/BRS.0b013e318241ad33.
- Moon BJ, et al. World Neurosurg. 2018;doi:10.1016/j.wneu.2018.06.023.
- Song J, et al. Spinal Cord. 2006;doi:10.1038/sj.sc.3101881.
- Yonemori K, et al. Am J Pathol. 1997;150:1335-1347.
- For more information:
- Yong H. Kim, MD, and Stephane Owusu-Sarpong, MD, can be reached at the department of orthopedic surgery at NYU Langone Orthopedic Hospital in New York. Owusu-Sarpong’s email: stephane.owusu-sarpong@nyulangone.org.
- Edited by Andrew Bi, MD, and Pooja Prabhakar, MD. Bi is a chief resident in the department of orthopedic surgery at NYU Langone. He will pursue a fellowship in sports medicine at Rush University Medical center following residency completion. Prabhakar is a chief resident in the department of orthopaedic surgery at the University of Washington. She will pursue a fellowship in foot and ankle surgery at Baylor University Medical Center following residency completion. For more information on submitting Orthopedics Today Grand Rounds cases, please email orthopedics@healio.com.
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