RAMB - Dezembro

anagement

degenerative

cervical

myelopathy

– A

update

ssoc

ras

2016; 62(9):886-894

891

Comparison of anterior discectomies

versus

corpectomy

Clinical outcomes [JOA, visual analog sclace (VAS) for

arm and neck pain] for two levels discectomies were com-

parable with one level corpectomy when both options are

feasible.

However, anterior cervical corpectomy and

fusion (ACCF) had a higher operative time and bleeding

amount compared with discectomies.

Additionally, dis-

cectomies obtained better improvements in segmental

height and postoperative cervical lordosis when compared

with corpectomy.

38,39

Of note, although corpectomies may

have a lower rate of pseudoarthrosis than multilevel dis-

cectomies, because of the fewer bone graft interfaces, there

was a higher stress on bone screws compared with discec-

tomy. The choice of one approach over the other depends

on surgeons’ preference and patient’s radiological findings.

Cervical arthroplasty

Cervical arthroplasty is also an alternative for treating

one or even two levels DCM secondary to degenerative

disc disease, especially those secondary to disc herniation.

The best surgical candidates are younger patients, without

facet joints arthritis and preserved cervical motion.

The

rationale for performing a cervical arthroplasty instead

of fusion is to preserve segmental motion and avoid ad-

jacent level disease, even though this has been questioned

since heterotopic ossification may occur in up to 50% of

the cases and ASD has not been shown to be decreased

by cervical arthroplasty in long term outcomes. Both

anterior cervical anterior discectomy and fusion

(ACDF)

and cervical arthroplasty are effective to treat disc her-

niation in DCM.

When performing a cervical arthro-

plasty, surgeons may be aware that an inadequate decom-

pression may lead to recurrence of myelopathic symptoms.

osterior

cervical

approaches

The posterior cervical approach is a straightforward alter-

native to decompress the spinal cord and nerve roots with

direct visualization.

However, unlike the anterior cervical

approach, posterior approaches require a preoperative

lordotic or straight cervical alignment.

Rigid local or

global kyphosis is a contraindication for posterior decom-

pression, as the spinal cord remains compressed and

stretched by the anterior elements.

Posterior approaches

avoid certain complications that are more common with

anterior approaches, such as dysphagia, dysphonia and

injury to the esophagus and carotid sheath contents.

Cervical laminectomy

The oldest and most traditional posterior cervical surgery

is a decompressive laminectomy.

It is based on direct

decompression of the spinal canal, enlarging its antero-

posterior diameter. Posterior approaches can directly

decompress the posterior elements such as the ligamen-

tum flavum, posterior bone, facet hypertrophy and also

indirectly decompress the ventral elements, shifting the

spinal cord posteriorly.

41,42

However, as stated previously, the main disadvan-

tages of cervical laminectomy are the inability to access

ventral pathologies, such as disc herniation and anterior

osteophytes, and the high risk of cervical deformity (post-

operative kyphosis), which can result in cervical pain and

late neurological deterioration.

Another complication

of an isolated cervical laminectomy is post-laminectomy

membrane that may cause recurrent stenosis.

Cervical laminectomy and instrumented fusion

The incidence of post-operative kyphosis after cervical lam-

inectomy may be as high as 50%, and dependent on many

factors, such as preoperative deformity, the presence of seg-

mental instability, removal C2 and/or C7 lamina, extensive

laminectomies, wide facetectomies and younger age.

41,43

Due

to the risk of post-operative instability, concomitant instru-

mented fusion is advocated as a prophylactic maneuver for

avoiding deformity and its consequences, especially when

treating multilevel spinal cord compression.

41,42

Similarly to a standard laminectomy, posterior in-

strumentation requires a lordotic or at least straight cer-

vical spine alignment. A wide range of modern surgical

techniques of instrumentation were described for the

cervical spine, such as lateral mass and pedicle screws,

laminar screws, pars screws for C2, among many others.

41,44

Cervical instrumentation may also avoid a new compres-

sion due to instability in the decompressed site. Disad-

vantages may include increasing surgical time and cost,

implant related complications and loss of cervical range

of motion, potentially increasing the chances of adjacent

level disease below and above the fixed levels.

Cervical laminoplasty

Laminoplasty is a surgical technique proposed in the

early 1970’s by Japanese surgeons for the treatment of

ossification of the posterior longitudinal ligaments (OPLL)

and congenital cervical stenosis.

45,46

The goal is to enlarge

the cervical spine canal and avoid post-operative kypho-

sis but also to preserve motion at the treated levels. This

motion preservation is the potential advantage of lami-

noplasty compared with laminectomy and instrumented

fusion, which can potentially avoid the complications

associated with arthrodesis.