Surgical decompression of the spinal cord is often
carried out soon after injury and, in some cases, long after injury.
Basically, with this surgery, various tissue or bone fragments that
compress the spinal cord and, in turn, compromise cord function are
removed. Depending upon the injury’s unique circumstances, decompression
can be accomplished by a variety of surgical approaches, including, for
example, approaching the compressed cord from either the front (anterior)
or back (posterior).
Although animal studies consistently suggest that
spinal-cord decompression soon after injury minimizes neurological
damage, human studies have been more ambiguous, i.e., some studies
suggest benefits and others do not. Results seem to depend upon
numerous factors, such as the nature of the injury, the timing of the
surgery, and specific outcome measures.
Earlier studies, including those carried out by
some of the pioneers of modern SCI medicine, suggested that
conservative, non-surgical approaches (e.g., postural techniques, bed
rest, etc), were the best way to fuse the injured spine and would avoid
exposing the patient to surgery-associated risks and neurological
However, as spinal surgery became more
sophisticated over time, minimizing its downside, the pendulum
increasingly swung towards the widespread use of surgical decompression
in acute SCI.
There has been a plethora of studies attempting to
address the effectiveness of surgical decompression. For example, Dr.
Stephen Papadopoulos et al (USA) concluded that “immediate spinal column
stabilization and spinal cord decompression…may significantly improve
neurological outcome.” In their study, 91 consecutively admitted
patients with acute cervical injuries were prospectively evaluated. Of
these patients, 66 had potential spinal-cord compression assessed by
magnetic resonance imaging (MRI); if present (54% of patients), they
underwent immediate surgical decompression and stabilization. For a
variety of reasons, 25 patients were treated outside of this protocol
(i.e., no surgical decompression) and served as a reference group.
The protocol-treated group fared better than
reference patients on several criteria. For example, 50% of protocol
patients improved from their initial Frankel grade compared to only 24%
of reference patients (Like the ASIA scale, Frankel scale ranges from
grade A, representing complete injury, to grade E, normal function). In
addition, eight protocol, but no reference, patients improved from
complete motor quadriplegia to independent ambulation. Finally, the
protocol patients needed less intensive-care and hospital time.
Using a meta-analysis approach, a number of recent
review articles have attempted to provide a big-picture assessment of
the many decompression studies published over the years. Although these
articles do not provide a thumbs-up or -down recommendation for the use
of decompression surgery in acute SCI, cumulative evidence suggests that
the procedure 1) does not increase the complication rate after acute
SCI, as suggested in earlier studies, 2) provides benefit for certain
types of injuries, and 3) reduces the time spent in intensive care.
Because definite data indicating its superiority over
conservative-management approaches are lacking, the procedure should be
considered a valid practice option but not a standard of care.
In 2010, Dr. Michael Fehlings and associates (USA)
published the results of a prospective survey, which asked 971 spine
surgeons about the timing of their surgical decompression procedures
after injury. Eighty percent preferred to decompress the spinal cord
within 24 hours. In the case of complete and incomplete cervical injury,
46% and 73% would operate within six hours, respectively.
Inhibition: A compressed cord compromises spinal-cord cell
viability by many potential mechanisms, including triggering apoptosis,
a form of post-injury neuronal cell death in which a programmed sequence
of events leads to cell elimination. This possibility was evaluated by
Dr. Kan Xu and colleagues (China) in rats with an experimentally induced
compression injury. Their results suggested that decompression reduces
the number of neuronal cells dying from such a mechanism.
Hypothermia Influence: As discussed later,
cooling procedures may preserve some neurological function after injury.
In animal studies, Dr. Peter Batchelor et al (Australia) demonstrated
that cooling can also expand the time period in which surgical
decompression remains effective. This is important because neurosurgeons
generally believe that more function can be preserved if the cord is
quickly decompressed; however, the desired timeliness can not always be
achieved for a variety of logistical and other reasons.
After creating a compression injury in rats, the
investigators cooled half of the animals to 33o C starting 30
minutes after injury. After 7.5 hours of cooling, decompression was
carried out. Eight weeks later, functional recovery and preservation of
spinal-cord tissue in the cooled rats were compared to the control rats
whose body temperature was maintained at a normal level. Functional
recovery was assessed by the commonly used BBB scale, which measures
recovery of hind-limb function on a scale from 0 (no hind-limb movement)
to 21 (normal walking). The rats that had been cooled before
decompression regained more function (9.5 BBB score) compared to the
controls (5.3 BBB score). In addition, the amount of injury-site tissue
spared was greater in the cooled rats. The investigators concluded that
“hypothermia may be a useful bridging therapy to prevent neurological
decline prior to decompressive surgery.”
As reviewed by Dr. Wise Young (New Jersey, USA), some studies suggest
that delayed surgical decompression, even long after the acute injury
phase, can produce some restored function.
The potential beneficial influence of such
decompression is, however, a confounding factor in interpreting the
results of new function-restoring SCI therapies that are emerging
throughout the world. Specifically, if the supposed function-restoring
intervention (e.g., cell transplantation) is structurally affecting the
cord’s injury site, it may be relieving some of the compression caused by
the injury. As such, it may be difficult to attribute any regained
function to the intervention alone; it may be just a consequence of the
decompression and the ensuing enhanced flow of blood and cerebrospinal
Dr. Henry Bohlman (photo) and colleagues (Ohio, USA)
have published a number of studies suggesting that
decompression may be beneficial for patients with SCI who are beyond the
acute phase of injury.
One of their studies focused on patients with
incomplete, cervical injuries. In these patients,
myelography (a form of x-ray examination using an injected dye) was used
to determine whether bone or vertebral disk fragments were compressing the
spinal cord’s anterior side. If so demonstrated, the compression was
alleviated through anterior-decompression surgery followed by
stabilization using iliac bone grafts. The time between injury
and decompression averaged 13 months (range, one month to nine years), and
patients were followed on average six years (range, 2-17 years). Of the 55
followed patients, 29 became functional walkers, and 39 recovered
additional upper-extremity function. Only nine regained no motor function.
In general, the more time that had elapsed since injury, less improvement
A similar study focused on patients with complete
quadriplegia. In this study, the
injury-to-decompression time averaged 15 months (range, one month to eight
years), and patients were followed on average five years (range, 2-13
years). Of the 46 followed patients, seven improved at least two
functional levels, and 18 improved one level. No motor improvement was
noted in 20 patients. Once again, more benefits were obtained by patients
who were decompressed sooner after injury.