Deepak Awasthi, MD and Ian Angel, MD
Department of Neurosurgery, Louisiana State University Medical Center
New Orleans, Louisiana
[Introduction | Clinical Material | Results | Discussion | Conclusion | References]
Introduction:
Gunshot wounds (GSW) are the 3rd most common cause of traumatic spinal
cord injuries in the U.S. civilian population. (23) However, the efficacy
and appropriateness of surgical management of missile injuries of the spine
and the subsequent functional recovery remain controversial.(16,31,33) In
addition, there is growing evidence that surgical exploration may not offer
significant improvement in the final recovery of function of patients with
low velocity GSWs to the spinal cord. (1,16,18,28) On the other hand, it
has been reported that surgery enhances functional recovery from GSWs to
the cauda equina and perhaps, in this case, decompressing the neural elements
by eliminating bony, bullet and disc fragments may be beneficial. (2,16,32)
Another reason cited for surgical management of GSWs to the spine is prevention
of subsequent spinal infections. (13,27) Although transperitoneal fragments
injuring the spinal cord and hollow organs, especially the colon, have a
greater tendency to cause local septic complications, visceral debridement
and extended antibiotic treatment seem to be sufficient, and there is no
need to remove apparently contaminated bullet fragments. (10,17,20,25,26,27,29,30)
Indeed, overall most studies in the literature recommend a conservative
(non-surgical) approach to GSWs to the spine. (1,10,30) The firm indications
for surgical intervention are usually progressive neurological deficits,
persistent cerebrospinal (CSF) leaks, incomplete neurological deficits with
radiographic evidence of neural compression (especially in the cervical
spine and cauda equina). Our management for GSWs to the spine had been very
conservative until recently. In the past 6 months, the LSU Neurosurgery
service has removed bullets from the spinal canal in all patients admitted
with a GSW to the spine with a retained bullet fragment. This report details
our one year experience with GSWs to the spine with a review of the literature.
Clinical Material:
The records of all patients managed by the LSU Neurosurgery service with
a GSW to the spine in 1996 were reviewed retrospectively. Fifteen patients
with GSW to the spine were managed by LSU Neurosurgery in 1996. The mean
age of these patients was 31.5 years (range:24-40 years) All injuries were
located in either the thoracic (10 cases) or lumbar (5 cases) spine. Figure
1 shows a typical axial CT scan revealing a bullet in the thoracic canal.
Axial CT scan view (bone windows) of the thoracic spine showing a retained bullet fragment in the canal. This fragment was located in the extradural space with no evidence of dural laceration intraoperatively.
Ten of 15 patients (67%) had a complete spinal cord injury. The
other 5 patients had an incomplete cauda equina injury. All of these patients
had plain x-rays of spine and all except one also had a CT scan at the appropriate
spinal level. After initial resusciation and, if necessary, visceral repair,
12 of the 15 patients had bullet and/or bony fragments in the canal- 8 of
these patients were taken to surgery.The other 7 patients were treated non-surgically
and all of them had a complete injury to the cord. In the non-surgical group,
4 patients had a bullet fragment in the canal (all of them were located
in the thoracic canal, none with abdominal visceral injury).
Of the 10 patients with a complete cord injury, 3 underwent surgical decompression
(via laminectomy) and removal of bullet fragments (all of these were within
the last 4 months of 1996). All 5 patients with an incomplete cauda equina
injury underwent surgical decompression and removal of bullet fragments.
Interestingly, in all patients with complete cord injury (except one) the
bullet was located in the extradural space- see Figure 2- with no evidence
of dural penetration and/or laceration.
Intraoperative photograph showing the extradural location of the bullet (white marker). This bullet was in the C7-T1 interspace region.
Whereas, in all cases (except one) with an incomplete cauda equina the bullet was located in the intradural space or there was a dural laceration. One case had bony fragments, but no bullet, in the lumbar spinal canal.
Results:
The mean followup period was only 4.5 months (range:3-12 months). Nevertheless,
the results are very illustrative. None of the patients with a complete
cord injury made any meaningful recovery after removal of the bullet and
decompression of the canal. All patients in the non-surgical group (complete
cord injury) also did not make any meaningful recovery. Whereas, all patients
with an incomplete cauda equina injury showed significant improvement in
the motor and sensory exam after bullet removal/ decompression. However,
the patients with bladder dysfunction still have not made any meaningful
recovery. None of the patients had a postoperative spinal fluid leakage,
fistula, infection and/or increase in their neurological deficits. In addition,
all patients complaining of hyperesthetic pain preoperatively had a significant
improvement in their pain syndrome after bullet removal from the spinal
canal.
Discussion:
There has been a dramatic increase in the number of GSWs to the spine
managed by the LSU Neurosurgery service. For example, in 1995 LSU Neurosurgery
was involved in the management of 6 patients with GSW to the spine, whereas
in 1996 this number jumped to 15 (over 50% increase). This trend has been
reported in other studies as well. (8,16) As a matter of fact, in civilian
life upto 13.6% of all spinal cord injuries and up to one-half of spinal
injures in young patients has resulted from low-velocity gunshot wounds.
(3,8,15) Thus, long-term functional disability as a consequence of spinal
cord injuries resulting from GSWs is an important problem that needs to
be addressed in our society.
Mechanism of Injury
The injury from a gunshot wound could be either direct or indirect.
Indirect injury results from shock waves or secondary fragments damaging
the neural elements. (14) Direct injury is a consequence of the projectile
crossing the spinal cord and/or canal causing compression, contusion, or
laceration of the spinal cord/ nerve roots, with or without laceration of
the dura. (2,5,14) Lipid peroxidation is unlikely to be an important mechanism
of further damage in penetrating cord injuries as evidenced by lack of significant
functional improvement after administration of methylprednisolone in patients
with GSW injuries to the spine.(19) However, the exact role of lipid peroxidation
and/ or the effects of monoamines, excitotoxins and prostaglandins in preventing
spinal cord injurues have yet to be fully evaluated.
Evolution of Strategies for Management
Most of the early published literature in the treatment of GSWs to the spine
was generated from experience in the military with high-velocity missile
wounds. Numerous significant differences, however, exist between these injuries
and low-velocity injuries secondary to handguns encountered in the civilian
experience. There is a much greater degree of wound contamination and tissue
destruction that occurs in the high-velocity injury. (11) This will frequently
lead to major differences in infections which can result secondary to these
high-velocity injuries. As a result, the treatment of military wounds may
be very different from civilian injuries (more surgically-oriented). In
addition to direct damage, high-velocity bullets may injure the spinal cord
by transmitting shock waves without actually penetrating the spinal cord.
(6)
Given the devastating implications of a GSW to the spinal cord, physicians
have adapted a wide range of strategies for managing spinal cord injuries
from missiles. These range from a tendency toward conservative management
of complete injuries in WWI (24), to a nonurgent and surgically oriented
view, taking advantage of antibiotics, in WWII (9), to swifter and more
aggressive surgical management and effective use of antibiotics in the Korean
and Vietnam Conflicts (4,12). The civilian situation, however, is more confusing
and efficacy of surgical management is often questioned. (1,2,10,17,18,23,30,32,33)
Indications for Surgery?
It has been argued that GSWs to the spine should be treated aggressively
by surgical debridement/ decompression, dural closure and/or bullet removal
in order to prevent potential complications such as plumbism and reactions
to copper or brass in cases of copper-jacket bullets (7,21), CSF fistulas
(1,27), and central nervous system/ local infections (17,26,27,29). In long-term
follow-up studies, metal intoxication has usually not been encountered.
(1) Cerebrospinal fistulas have been encountered in only small percentage
of patients with bullet wounds. (1,27) Indeed, Cybulski et al do not consider
CSF fistulas as a major complication. (5) There were no cases of CSF fistula
in our patients. With respect to prevention of infections, it has been shown
in several studies that patients who underwent surgery seemed to have a
higher risk of meningitis or focal infectious complications. (1,30) Even
the efficacy of spinal debridement of transperitoneal wounds (including
colonic injuries) to prevent spinal infections has been questioned. (17,20,26,27,29)
Thus, the fact that foreign bodies such as projectile fragments could be
a source of infection is controversial.
The other important indication for surgical intervention has been to relieve
spinal cord and/or cauda equina or nerve root compression from primary or
secondary fragments, herniated discs or hematomas, (2,16,22,32) Although
it would be seem logical that removal of offending compressive fragments
could help relieve radicular pain and promote functional recovery in incomplete
cauda equina or spinal cord injuries (2,16,32), several reports indicate
that surgery does not significantly effect the final recovery of function,
whether cord damage is complete or incomplete (11,18,27,28,30,33). Surgical
exploration, however, has been advocated for GSW injuries of the cauda equina.
(2,5,16,32) Even in this scenario, studies have shown that neurological
status or functional change was unaffected by surgical exploration.
(1,25) On the other hand, all patients in our small series with an incomplete
cauda equina injury improved in their functional capacity after surgical
decompression and bullet removal.
It seems that most studies have shown that surgery is of little benefit
and, in general, leads to increased complications. (1,30) Thus, we are back
to the devasting outlook of these wounds as seen by war-time surgeons. Is
there nothing we can offer these patients? At our institution, we have taken
an aggressive approach to these injuries. Only long term follow-up will
tell if this approach makes a difference in these patient's lives. Unlike
several studies in the literature, we have not seen an increased
complication rate after surgery. Another interesting observation has been
the extradural location of several of these bullets- this makes the surgical
intervention relatively straightforward with minimal morbidity.
Conclusion:
Although, still, very controversial, we feel that a bullet in the spinal
canal should be removed if it is technically feasible. We think this will
give the spinal cord and/or cauda equina/nerve roots the best possible chance
of recovery and eliminate any possibility of infection or metal intoxication.
Long term follow-up and standard protocols will be needed to further elucidate
the efficacy of our approach. These long term studies have been planned
at LSU.
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