88 Anterior versus Posterior Approach to the Cervical Spine

Case 88 Anterior versus Posterior Approach to the Cervical Spine

Amgad S. Hanna and Remi Nader

Fig. 88.1 Cervical spine T2-weighted magnetic resonance images with (A) midsagittal section and axial sections through (B) C3–C4, (C) C4–C5, (D) C5–C6, and (E) C6–C7, respectively.

Clinical Presentation

A 37-year-old man who is human immunodeficiency virus-(HIV)-positive presents with progressive ataxia over 2 weeks, clumsiness, and dropping of objects with both hands.

He has a longstanding history of neck pain.

Hyperreflexia and patchy sensory loss are noted on examination.

Magnetic resonance imaging (MRI) of the cervical spine is obtained and shown in Fig. 88.1.

Questions

Interpret the MRI scan.
What is your management?
What factors will favor an anterior versus a posterior surgical approach?
Postoperatively, the patient does not improve (no obvious intraoperative complications). What do you tell the patient?

Answers

Interpret the MRI scan.

Cervical canal stenosis is seen extending from C3 to C7 with multiple-level disk bulges, more so at C4–C5.
The sagittal images do not fully account for the narrowing seen in the axial cuts.
There is increased signal intensity of the cord on T2-weighted MRIs demonstrating damage to the spinal cord, likely from the stenosis.
The region of the posterior longitudinal ligament (PLL) is thickened and hypointense. This could be ossified PLL (OPLL); obtaining a computed tomography (CT) scan would confirm this finding, if present.
No bony changes or extradural tissues are seen to suggest the diagnosis of epidural abscess, which could well be a possibility in an HIV scenario. HIV can also lead to neuropathic changes and changes within the cord.

What is your management?

This patient is myelopathic in the context of significant cervical stenosis; therefore, surgery is the most appropriate treatment measure in this case.
In the meantime, an infectious workup for HIV should be performed (including CD4 count, viral load, etc.). Acquired immunodeficiency syndrome-(AIDS)-related myelopathy should also be in the differential diagnosis.

What factors will favor an anterior versus a posterior surgical approach?

Anterior approach would consist of multilevel diskectomies versus corpectomies. It would directly address the compressing pathology and correct the kyphosis. However, there is a high incidence of pseudoarthrosis if done as a stand-alone procedure.1,2

Posterior approach alone would consist of laminectomies ± lateral mass fusion versus laminoplasties from C3–C6. It would not correct the kyphosis, and the cord may remain draped over the anterior pathology.^3,4

This stand-alone procedure needs to be supplemented by bracing with at least a hard cervical collar or halo (or SOMI brace) placement to limit motion during the healing process.

Although it may be perfectly reasonable to perform a stand-alone anterior or posterior procedure, the ideal procedure in this patient, if medically tolerable, is a circumferential procedure. This may include C3–C4 and C4–C5 anterior diskectomies, C6 corpectomy, allograft, and plating, followed by supplementation with posterior C3–C7 lateral mass fusion (and possible posterior decompression). The C7 lateral mass is usually small (confirmation of bony landmarks with CT is important) and usually takes a pedicle screw better.^5,6

Anterior approach advantages and disadvantages^1,2:

Pros

With adequate distraction, it can correct the kyphotic deformity.

It can address anterior pathology such as disks and bony spurs.

Sufficient distraction can unbuckle the ligamentum flavum and indirectly treat a posterior pathology.

Cons

There is a risk of cranial nerve (dysphagia, dysphonia) and vascular injury.

It requires bony fusion and the associated morbidity of bony fusion.

There is a high risk of subsidence in osteoporotic patients.

There is a lesser likelihood of fusion in greater than two-level construct cases unless it is supplemented with a posterior approach procedure.

Posterior approach advantages and disadvantages 3,4:

Pros

It is technically easier and therefore more suitable for older and osteoporotic patients.

There are virtually no risks to the cranial nerves and carotids (i.e., good procedure for professional singers).

It can address posterior pathology such as ligamentum flavum directly.

There is lower risk of incidental durotomy in cases of OPLL.

Cons

There is risk of kyphotic deformities or instability in pure laminectomy cases (if too much facet is taken).

There is an inability to directly address anterior pathology.

C5 nerve root palsy is described more often with posterior decompressions.
Postoperatively, the patient does not improve (no obvious intraoperative complications). What do you tell the patient?
- The main goal of surgery is to stop further deterioration.
- Improvement rate of neurologic function is ~50% (ranging from 37 to 85%) in myelopathic patients; therefore, it is not unusual to see no change postoperatively.^6–8
- Also, he has myelopathic changes within the spinal cord on the MRI, and some of his symptoms may be related to HIV myelopathy and peripheral neuropathy.
- One management approach, at this stage, would be to continue observation while initiating rehabilitative measures such as physical therapy.