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Copyright © 2008 Undersea and Hyperbaric Medical Society, Inc 427
UHM 2008, Vol. 35, No. 6 – Postoperative Discitis and HBO2
Antibiotic and hyperbaric oxygen therapy in
the management of post-operative discitis.
M. KUTLAY1, A. COLAK1, H. SIMSEK1, S. YILDIZ2, K. TOPUZ1, S. KAYA1, A. CETINKAL1,
M. DEMIRCAN1
GATA Military Medical Academy Haydarpaşa Training Hospital, 1 Department of Neurosurgery, 2 Department of Undersea and
Hyperbaric Medicine, İstanbul-Turkey
Kutlay M, Colak A, Simsek H, Yildiz S, Topuz K, Kaya S, Cetinkal A, Demircan M. Antibiotic and hyperbaric
oxygen therapy in the management of post-operative discitis. Undersea Hyperb Med 2008; 35(6):427-440.
OBJECTIVE: Despite the use of antibiotics, the management of postoperative discitis (POD) still presents a
challenge. This study was designed to evaluate the effect of adjuvant hyperbaric oxygen (HBO2) therapy on
the duration of antibiotic treatment. METHODS: Between 1999 and 2004, 22 patients diagnosed with POD
were treated with antibiotic and HBO2 therapy. There were 14 male (63.6 %) and 8 female (36.3 %) patients,
and their mean age at the time of surgery was 45.4 years (range, 20-59 years). Diagnosis of a POD was
established on the basis of clinical, laboratory, and radiographic findings. All patients were given a 4-week
course of vancomycin (1g IV every 12 h). Additionally, patients received HBO2 (100% O2 at 2.4 ATA for 90
min) twice daily for the initial five consecutive days, and an additional treatment (100% O2 at 2.4 ATA for
90 min daily) was given for 25 days. The duration of follow-up was 24 months. RESULTS: This treatment
modality allowed infection control and healing for all 22 patients with 0% recurrence rate. HBO2 treatment
was tolerated well. CONCLUSION: This series represents the first reported group of POD patients treated
with antibiotic and HBO2 therapy. Our preliminary results indicate that the length of time on antibiotic therapy
can be shortened with the use of HBO2 as an adjunctive treatment. Erythrocyte sedimentation rates and serum
C-reactive protein levels returned to the preoperative levels earlier (within 8-30 days after the initiation of
treatment) and a reasonable length of immobility was obtained (mean 12.2 days). After completion of the
one-month period of antibiotic and HBO2 therapy, patients were accepted disease-free regarding pain and
mobility.
INTRODUCTION
Postoperative discitis (POD) was first
described as a clinical entity by Turnbull in
1953 (1). Since that time it has been shown to
be an uncommon but one of the most disabling
causes of failed back surgery or might be
accepted as a late complication of spinal surgery
(2-9). It has also been reported after minimally
invasive spinal procedure such as discography,
chemonucleolysis, and myelography (10-
12). According to the literature, the incidence
of postprocedural discitis after any type of
spinal procedure ranges from 0 % to 4.0 %
(2-8,11,13-21). POD may lead to long-lasting
and sometimes permanent morbidity (3,6-9).
Despite the use of antibiotics, the management
of POD still presents a challenging problem
(2,4-6,8,9,22). The current mainstay for discitis
treatment is a combination of bed rest and
prolonged administration of antibiotics; surgical
intervention is rarely necessary in patients
failing conservative treatment (4,7,17,19,20,23).
Although the duration of medical therapy is
variable, six weeks of intravenous antibiotics
followed by an additional 6 weeks of oral
antibiotics is a course commonly administered
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UHM 2008, Vol. 35, No. 6 – Postoperative Discitis and HBO2
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(2,7,8,20,24-27). However, the period of strict
bed rest and antibiotic treatment can last up
to several months, and this might lead to
undesired dramatic medical and psychosocial
consequences (3-8,13).
Hyperbaric oxygen (HBO2) therapy,
that is the administration of 100% oxygen at
pressures greater than atmospheric pressure,
has become a recognized treatment for a
number of disorders such as gas gangrene,
severe necrotizing soft tissue infections, and
chronic refractory osteomyelitis (28-32).
HBO2 therapy has also been shown to have a
beneficial effect in the management of a variety
of surgical infections including postoperative
neurosurgical infectious complications (32-
37). On the basis of considerations similar to
the rationale for the use of HBO2 therapy to
treat these disorders, we think that it may be
worthwhile to try a combination of HBO2 and
antibiotic therapy in the management of POD.
PATIENTS AND METHODS
Between September 1999 and August
2004, 809 patients underwent microsurgical
discectomy because of herniated lumbar discs
at the Neurosurgical Department of GATA
Haydarpaşa Training Hospital..All patients had
preoperative radiating leg pain refractory to
conservative therapy. All surgical procedures
were performed via a standard midline
microsurgical approach. Prophylactic antibiotic
therapy (intravenous cefuroxime, a second-
generation cephalosporin) was administered
preoperatively (just before induction of
anesthesia), and postoperatively (every 12
hours for the first 24 hours). Immediate
postoperative course of all of the patients was
uneventful in the first 24-48 hours till their
discharge. During the study period of 5 years,
22 patients developed POD, accounting for
an incidence rate of 2.7 %. Fourteen patients
(63.6 %) were male and eight (36.3 %) were
female. The mean age of 22 patients at the
time of surgery was 45.4 years (range, 20-59
years). Characteristics of these 22 patients are
summarized in Table 1, see page 436. Informed
consent of each patient was obtained before
enrolling them in the study. Upon admission
of the patients with symptoms of discitis such
as progressive back pain, restriction of back
motion, they were hospitalized for further
evaluation. In addition to the neurological
examinations including bed-shaking test, routine
laboratory evaluation with complete blood
count, erythrocyte sedimentation rate (ESR),
C-reactive protein (CRP), blood cultures, and
urine analysis were performed. Initially, plain
radiographs including flexion and extension
views (in nine patients could not be obtained
because of severe pain), and then MR images
(before and after i.v. contrast administration)
and CT scans (when necessary) were obtained
to rule out other causes of postoperative pain,
such as recurrent or residual disk herniations,
lateral recess stenosis syndrome, epidural
abscess, scar tissue formation, postoperative
segmental instability. The diagnosis of discitis
was established when all three of the following
criteria were present:1) clinical symptoms
and signs: recurrent low back pain, decreased
back motion, paravertebral muscle spasm,
and positive bed-shaking test (pain can be
aggrevated by shaking the bed back and forth);
2) laboratory findings of elevated ESR, and CRP
values; 3) MR imaging findings compatible
with discitis: decreased signal intensity on T1-
weighted images, increased signal intensity on
T2-weighted images in both the disc space and
adjacent vertebral bodies, and enhancement
of the same areas with gadolinium (4,17,2
0,25,27,38,39,40). The following clinical
and paraclinical data were also collected; 1)
demographic characteristics (age,sex); 2) time
(days) between the operation and the onset
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UHM 2008, Vol. 35, No. 6 – Postoperative Discitis and HBO2
429
of symptoms, type of pain, and inflammatory
signs in the spine (local erythema, swelling
and/or heat), fever (>38o C), white blood cell
count, blood cultures; 3) patient-related risk
factors of chronic underlying diseases (e.g.,
diabetes mellitus, steroidal, or nonsteroidal
anti-inflammatory therapy, chronic renal
failure, chronic respiratory failure, heart
failure, chronic alcoholism, intravenous drug
use, previous bacteremia or focal infections).
According to the findings obtained from
neurological examinations performed at
admission, the patients were graded as follows:
patients able to stand up and walk without
assisstance (Grade I), patients able to stand up
and walk with assisstance despite pain (Grade
II), and the patients unable to stand up and walk
because of severe pain (Grade III). A visual
analog scale (VAS) was also used for assessing
the patient’s pain levels.
All patients were treated with
vancomycin 1g IV every 12 h for a 4 wk
course, analgesics, and bed rest. The antibiotic
therapy was planned to be changed according
to the results of blood cultures. Additionally, in
accordance with our protocol, patients received
HBO2 (100% O2 at 2.4 ATA for 90 min) twice
daily for the initial five consecutive days, and
then an additional treatment (100% O2 at 2.4 ATA
for 90 min daily) was given for 25 days (Figure
1). The patients were mobilised in lumbo-
sacral corsets when she or he was comfortable.
The efficacy of treatment was followed by
serial detection of laboratory markers and
clinical examinations. WBC count, ESR and
CRP levels were determined every 2 days for
the first week, and thereafter twice a week for
the duration of therapy. Invasive procedures
for identification of pathogens responsible for
discitis were reserved for patients with persistent
clinical findings, presence of increasing course
or consistently elevated ESR and CRP values
without any down-ward progression. At the
end of the treatment, neurological examinations
and sequential ESR and CRP levels were
performed monthly for the first three months
and then once in three months time for the rest
of the first year. Likewise, we obtained the
first follow-up MR images at the end of the
treatment, and regular follow-up MRI studies
were planned to be performed till the detection
of complete resolution of the MRI findings of
discitis with the frequency of 3-month intervals
for the first year and then 6-month interval
fort the second year. Although follow-up MR
images might reveal normal signal intensity,
conventional AP/L, and dynamic radiographs
were obtained every 6 months for two years. At
the final examination when MR images revealed
complete resolution of discitis findings, current
clinical outome was graded as ‘excellent’,
‘good’, ‘ no change’, or ‘poor’. The result
was defined as excellent when return to full
activity without any symptoms was confirmed.
A good outcome was assigned if lumbar pain of
low intensity was periodically present but did
not alter the daily activity of the patient, who
remained in the same employment as before
the operation, no change when no noticeable
change was observed in the symptoms before
and after treatment and poor when the symptoms
were worse after treatment.
Fig. 1. Multiplace hyperbaric chamber; 100% oxygen
given by hood at 2.4 ATA.
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UHM 2008, Vol. 35, No. 6 – Postoperative Discitis and HBO2
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RESULTS
All patients who were enrolled in the
study had received a clinical diagnosis of a
POD, on the basis of clinical, laboratory, and
radiographic findings. The surgical procedure
and the postoperative course of all the patients
were uneventful.They had experienced good
relief of symptoms immediately after surgery
(up to in a week’s time). The mean interval
between surgery and onset of POD symptoms
was 21.3 days (range 4-77 days. Most of the
patients (n=18, 81.8 %) became symptomatic
within 4 weeks after surgery. There were
only five patients who presented discitis
symptomatology in the first week and three of
them were diabetic. All patients had moderate
to severe back pain. Nine patients (40.9 %)
rated their pain 10 over 10 on the VAS. The
mean VAS was 8.8. On admission, 6 patients
(27.2 %) were able to stand up and walk without
assistance (Grade I), 7 patients (31.8%) were
able to stand up and walk with assistance (Grade
II), and 9 patients (40.9%) were unable to stand
up and walk because of severe pain (Grade
III). The pain was described as continuous and
deep-seated and was frequently associated with
morning stiffness (86.3%). It was accompanied
by severe paravertebral muscle spasm in
17 cases (77.2%), and was radiating into
the buttocks, thighs, groin, perineum or the
abdomen. Typically, it was easily exacerbated by
any motion, or attempts at examination. It was
noteworthy that, bed-shaking test was positive
in all patients, regardless of their clinical grade.
Neurological examination revealed that none
of these patients had neurological deterioration
comparing with the preoperative findings.
Straight leg raising tests were positive at small
angles and it could not even be tested in most
of the Grade III patients. The surgical skin
incision appeared to heal uneventfully in all
patients. Local erythema, swelling,or a draining
sinus were not seen. Fever (to as high as 380
C) was present in only 54.5 per cent of the
patients. ESR and CRP values were increased
in all patients. The highest ESR ranged between
42-110 mm/hour (mean, 67mm/hour), and the
highest CRP values ranged between 15-125
mg/L (mean, 41mg/L). 7 of 22 patients had
WBC counts above 10,000/mm3.
Initially obtained plain radiographs
showed little evidence of intervertebral
discitis. There was some decrease in disc
height (however this frequently accompanies
discectomies). In contrast, the characteristic
MRI findings of discitis in the acute stages
were found in all of the patients. The involved
intervertebral disc space and adjacent vertebral
bodies were visualized as a region of low
signal intensity on T1-weighted images and
high signal intensity on T2-weighted images.
The addition of intravenously administered
gadopentate dimeglumine gadolinium resulted
in homogeneous enhancement of the same
areas. The intervertebral disc spaces were
narrowed in all patients. Vertebral edema was
also present in 100 % of patients. This was
particularly important in differential diagnosis
of the patients who had the diagnosis of discitis
in the first week after surgery, because, in the
early postoperative setting, the absence of
vertebral edema has strong negative predictive
value for infectious discitis (64).
During their treatment, none of the
patients suffered neurological deterioration.
In the majority of the patients (n=19, 86.3%),
elevated ESR/CRP values returned to the
preoperative baseline values within 8 to 30 days
(mean 21 days) after initiaton of the treatment.
In the remaining 3 patients, 1more month
was needed for ESR/CRP values to come to
baseline values. They remained at bed rest until
they were comfortable. They were mobilized in
lumbosacral corsets, in which they remained for
an additional 4 weeks. The overall mean time
of immobilization was 12.2 days (4-22 days).
It was 19.6 days (17-22 days), 9.4 days (7-13
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UHM 2008, Vol. 35, No. 6 – Postoperative Discitis and HBO2
431
days), and 4.5 days (4-6 days) in Grade III, II,
and I patients respectively.
Blood cultures were positive in only 36
% of patients. The organisms from these cultures
included methicillin-sensitive Staphylococcus
aureus in 5 cases, methicillin-resistant S. aureus
in 2, and S. Epidermidis in 1. Because of the
clinical improvement and the presence of a
downward trend of the ESR, CRP values, needle
biopsy for confirmation of the diagnosis and
adjustment of the antibiotic therapy according
to the results of culture and sensitivity studies
were not required for any patient in this series.
Although, clinical and laboratory findings of
rapidly resolving infection were determined
after only 25 HBO2 sessions in two patients,
treatment was not discontinued early because
of our protocol. HBO2 treatment was tolerated
well. In the entire series of 22 patients managed
with this protocol, no signs of cerebral oxygen
toxicity were observed nor were other adverse
effects of pressurization seen.
After completion of the one-month
period of antibiotic and HBO2 therapy, all
the patients were discharged in satisfactory
condition regarding pain and mobility. The
mean VAS at discharge was 2.2. While 7
patients were entirely free of back pain, the
other 15 patients had pain levels between 1 and
4 on the VAS.
MR images performed after completion
of the treatment and sequential MRI’s performed
in the follow-up period showed progressive
increase in signal intensity within the disc and
adjacent vertebral body marrow on T1-weighted
images and decrease in signal intensity in the
same areas on T2-weighted images. However,
radiological decline of inflammatory symptoms
appeared to come after the improvement of
clinical and laboratory findings (Figure 2
A,B,C,D,E,F,G, see page 436). Normalization
of T1 and T2 signal pattern of disc, adjacent
vertebral bodies and paravertebral soft tissue
were discernable on MR images obtained about
9-12 months (15 patients after 12 months, 7
patients after 9 months) after treatment (Figure 3
A,B,C,D,E,F,G) see page 437. Plain radiographs
obtained at the end of the two-year follow-
up period, revealed a complete spontaneous
interbody fusion in only three patients (13,6%).
There have been no recurrences in this follow-
up period, and none of the patients required
surgery for debridement of the infected disc
space, decompression of neural elements or
spinal instability. At their last follow-up visit,
according to the study criteria, fourteen patients
(63.6 %) were graded as excellent, 8 (36.3%)
as good. There were no patients graded as no
change or as poor.
In all patients, predisposing factors
were also searched. The main predisposing
factor was diabetes mellitus. Five patients (22.7
%) were diabetic. Other risk factors consisted
of chronic alcoholism (n=1, 4.5%), long-term
steroid administration (n=1, 4.5%), smoking
(n=2, 9.0%, one of them was also diabetic), and
another one (n=1, 4.5%) had a body mass index
greater than 30kg/m2. The remaining fourteen
patients (63.6 %) did not bear any predisposing
factors. None of the patients beared middle ear
barotraumas. See Table 2 page 438.
DISCUSSION
POD is considered a severe
complication of lumbar disc surgery. Although
it is controversial whether discitis can be caused
by an aseptic or infectious process, recent data
suggest that POD is almost always bacterial
(2,3,7,10,11,14,17,19,21,41). The majority of
spine surgeons think that it results from direct
inoculation of an offending pathogen into the
avascular disc space (8,9,11,21,23,25,42). In
all reported series, the clinical manifestations
of postoperative disc space infection have
followed a very similar pattern (7,8,23,25). The
usual clinical scenario includes severe recurrent
back pain after the initial relief of symptoms,
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UHM 2008, Vol. 35, No. 6 – Postoperative Discitis and HBO2
432
but the duration of the postoperative pain relief
period is variable ranging between a few days to
10 weeks after surgery (2,5-9,13,19,20,23,25).
In the present study, the mean interval between
surgery and the onset of POD symptoms onset
was 21.3 days (range 4-77 days). There may
be a delay in diagnosis because reappearance
of spinal pain after surgery may be attributed
to recurring disc herniation, unsatisfactory
performance and/or outcome of surgery, or
psychoneurotic disorders (4,7,18,23,38). The
pain, most common presenting symptom in
every series is usually out of proportion to the
clinical signs, and the physical examination is
generally remarkable. The relative paucity of
physical findings in the face of the extreme pain
suffered by the patient may lead to misdiagnosis
of conversion disorders, and may also lead
to delay in accurate diagnosis in this patient
population (7,18,23). However, exacerbation
by virtually any motion of the spine including
jarring of the bed is one of the most important
characteristics of this pain. In our series, not
surprisingly, back pain was the most common
presenting symptom, and bed-shaking test
was positive in all 22 patients whereas it was
negative in the follow-up evaluations of the rest
of 809 patients who underwent uncomplicated
disc surgery. Therefore, we think that the
presence of positive bed-shaking test should
raise the suspicion of discitis.
The early and accurate diagnosis
frequently depends on a combination of
clinical, laboratory and imaging findings.
The diagnosis is strongly suggested by a
persistently elevated ESR, CRP values, and by
typical changes on MRI (3,4,7,8,13,20,23,34,3
8,40). Although elevation of the ESR and CRP
is almost uniformly present in discitis, they are
supportive but not confirmatory of the diagnosis.
A raised ESR and CRP values secondary to
the operation or underlying disease may be
confusing (2,14,16,18,20,38). Additionally,
the elevation may be masked in patients
taking corticosteroids (7,15,26). However,
they are very useful parameters for following
the course of POD and also for following the
response to therapy (3,7,8,20,23,38,42,43). In
the current series of patients, all of them have
an associated elevation of the ESR, and CRP
level at time of diagnosis. During the course
of antibiotic and HBO2 treatment, all patients
have a steady decline, and the values returned
to preoperative baseline values within 8 to 30
days (mean 21 days). The decline of ESR and
CRP values significantly corralated with the
clinical improvement.
The key to accurate and early diagnosis
is the use of reliable confirmatory diagnostic
study. In recent years, MRI has become the
imaging modality of choice in diagnosing POD
with reported sensitivity and specificity of
more than 92% (4,8,13,20,23,38-40). MRI can
demonstrate disc space changes consistent with
an infection as early as 3 to 5 days after operation
(40) These changes include a reduction in
signal intensity on T1-weighted images and
an increase in signal intensity on T2-weighted
images in the involved disc, and adjacent
vertebral bodies. Post-contrast enhancement in
the same areas also has diagnostic value as a sign
of bacterial infection (9,17,22,25,38-40,44).
MRI, especially with gadolinium enhancement
can also be regarded as the preferred imaging
method for monitoring response of treatment
(9,17,44-46). An increase of the T1 signal
due to fatty marrow, and a decrease of the
T2 signal and of the enhancement following
gadolinium application have been described as
definitive signs of healing (44,46). When the
inflammatory process responds well to medical
management, the bone marrow changes appear
to resolve first at 2-4 months after, with the
disc space enhancement persisting longer in
many cases (17,22,24,38,45). Normalization of
T1 and T2 signal pattern of disc, and adjacent
vertebral bodies was also reported at about
two years or later (9,13,22). However, in our
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UHM 2008, Vol. 35, No. 6 – Postoperative Discitis and HBO2
433
study, radiological decline of inflammatory
symptoms could be detected at the end of the
first month, and follow-up MRI studies showed
the normalization of the signal intensity at about
9-12 months after completion of the therapy.
Despite dramatic improvements in
diagnostic capabilities particularly afforded
by MRI, effective treatment of discitis is
still a challenge and the management of
discitis has also been a matter of controversy
(2,20,22). Although a universally accepted
treatment protocol has not been written and the
management decisions vary among surgeons,
the current mainstay for discitis treatment
is a combination of bed rest and prolonged
administration of antibiotics( 4 weeks to 6
months) (4,5,7,8,15,19,20,22-27,47). Patients
rarely develop persistent infection, pain,
epidural abscess formation, and/or spinal
deformity despite the aforementioned treatment
modality of antibiotics and bed rest leading
to surgical intervention (2,7,16,18,20,23-
27,38). Though conservative treatment along
with spinal immobilization has been shown
to produce good long-term outcomes in the
majority of patients, the period of strict bed
rest can last up to several months, and might
lead to dramatic medical and psychosocial
consequences (2,4-7,9,23). Additionally,
major complications (e.g., colitis, renal failure,
allergic reactions) as side effects of long-term
antibiotic therapy were also reported (24). The
duration of antibiotic therapy recommended
in the literature for POD has been variable.
Systemic antibiotics are usually administered
by i.v. infusion for a minimum of 4-6 weeks,
followed by oral administration for a further
2-3 months (2,4,5,8,9,15,20,23,24). Parenteral
therapy for less than four weeks result in a
higher rate of failure (7,43). In fact, repeated
laboratory markers as well as the clinical
response of the patient are the key parameters
in determining the exact duration of antibiotic
administration (3,7,20). In our study, although,
parenteral antibiotic and HBO2 therapy were
administered for a total of four weeks, even
in patients without bacteriological diagnosis,
this treatment modality allowed rapid infection
control and healing for all 22 patients with 0 %
recurrence rate. The main difference between
our study and those reported in the literature
is the reduced duration of antibiotic therapy.
We think that this might be attributable to some
beneficial effects of HBO2 therapy.
HBO2 therapy has been used in the
management of a variety of infections and
postoperative complications in bone and soft
tissue as a supplement to medical treatment (28-
32,36,37). Most infectious tissues including
infectious osteomyelitic bones are hypoxic
because of ischemia secondary to inflammation-
induced tissue edema (28,48). However,
adequate delivery of oxygen to the wound tissue
is vital for the healing process and for resistance
to infection (20,49). In the surgical procedure,
injury to end plates, operative trauma to small
vessels, hematomas in the intervertebral space,
and necrotic tissue caused by surgery provide
viable culture specimens and are risk factors
for postoperative intervertebral disc space
inflammation (18,20,23,25). Once inoculated
in an adult disc, which is an avascular structure,
the process of discitis begins. Because of
infections, and concurrent inflammation,
oxygenation and resistance to infection are thus
further compromised. The leukocyte bacteria-
killing capacity is substantially impaired in
hypoxic surroundings (29,48-51). It has been
shown that HBO2 therapy increases the oxygen
tension in infected tissues, including bone (51).
Improved tissue oxygen tensions in ischemic
tissues stimulates bactericidal action of white
blood cells and inhibits the growth of aerobic
and facultative anaerobic bacteria by inducing
a variety of metabolic effects involved with
the synthesis of proteins, nucleic acids and
essential cofactors of metabolic reactions
(29,31,51-56). These effects of this treatment
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UHM 2008, Vol. 35, No. 6 – Postoperative Discitis and HBO2
434
are mediated in large part by oxygen-based free
radicals that oxidize proteins and membrane
lipids, damage DNA, and inhibit metabolic
functions essential for growth (29,31,54,57).
The lack of an adequate vascular supply to the
adult disc decreases the ability of the patient’s
immune system to fight the infection (20).
Therefore, angiogenesis is critically important
in wound healing. It has also been shown that
HBO2 therapy induces the formation of new
capillaries, making the tissues less ischemic
(30,58). It exihibits dose-dependent angiogenic
effects by causing eight-to ninefold increase in
the vascular density of tissues (30). Improved
vascularity not only improve tissue oxygen
tensions and host defenses but also facilitates
entry of leukocytes, antibodies and antibiotics
to the infective focus (28,29,48).
Some authors advocate the use of
percutaneous discal biopsy to provide a definitive
pathogen and thus enhance the efficacy of
antibacterial treatment (3,5,7,12,14,15,26,59).
Using computed tomography guidance or
fluoroscopy assistance, the complication rate
of the needle biopsy is now acceptably low,
but the rate of false negative results is still
high (11,20,22,23,25,59,60). False positive and
false negative cultures also limit the accuracy
and reliability of the bacteriologic diagnosis. A
positive culture from the material obtained by
percutaneous needle biopy is reported to occur
in only 50-70 % of cases (7,8,15,20,23,25).
Of those that are positive, over 90 percent
grow a Staphylococcus species, which are
found in up to 100 % of cases in some studies
(2,7,20,21,25,26,60-62). Other less common
organisms include anaerobic organisms,
Streptococcus viridans and other Streptococcus
species, Escherichia coli, Pseudomonas
aeruginosa, fungi and others (15,23,60-
62). Therefore, in the abscence of definitive
microbiological data, empiric broad-spectrum
antibiotic coverage including agents effective
against S. aureus is recommended (7,18,25,27).
On the other hand, HBO2 can be considered as
a wide-spectrum antibiotic (28,29,31,55); a)
the lack of adequate antioxidant defenses in
anaerobic microorganisms contributes to their
susceptibility to HBO2 (31); b) the growth of
some aerobic bacteria including Escherichia
coli and other enteric bacteria, P aeruginosa
is inhibited by HBO2 (56,57,63); c) Hyperoxia
is fungicidal for C. Albicans and several other
Candida species (33,37). HBO2 also potentiates
the activity of certain antimicrobial agents
by elevating pO2 in ischemic tissue to levels
required for optimal activity of antimicrobials
(e.g., vancomycin, aminoglycosides, certain
sulfonamides, fluoroquinolones, trimethoprim)
or by altering the oxidation-reduction potential
in bacteria (e.g.,nitrofurantoin, metronidazole)
(28,29,31,51,56). Furthermore, HBO2, by
itself has been shown to be as effective as
cephalosporins in controlling staphylococcal
osteomyelitis in rabbits (64).
Dramatic beneficial effects of HBO2
therapy were also observed for patients
with spinal infections caused by a variety
of microorganisms (28,29,32,34,36,37).
Ravicovictch and Spallone obtained good results
for treatment of spinal epidural abscesses with
HBO2 therapy after laminectomy (32). Larsson
et al., applied HBO2 therapy for the treatment of
neurosurgical infections after cranial and spinal
surgeries (36). Five of their seven patients
with osteomyelitis and wound infections after
spinal surgery showed resolution, with the use
of combined therapy and without removal of
foreign materials. Moreover, they presented a
case of MRSA wound infection that was cured
solely by HBO2 therapy. The results obtained
from our study also strongly suggest that HBO2
therapy is a useful adjunctive therapeutic
measure in the management of POD as in other
spinal infections. However, the issues of the
dose and duration of HBO2 therapy remain
unsettled. With our protocol of 35 sessions
at 2.4 ATA, we may have overtreated some
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435
patients. We believe that time will tell whether
or not 2.4 ATA/35 sessions is the optimal
treatment pressure for these patients, and future
refinements could certainly improve individual
responses to treatment. In the entire series of 22
patients managed with this protocol, no signs
of cerebral oxygen toxicity were observed nor
were other adverse effects of pressurization
seen.
The overall long-term prognosis of
discitis varies markedly in different series,
different authors report variable success in
returning patients to work. The percentage
of patients who were unable to resume their
former work varied from12 % to 90 % (2,4,6-
8,18,23). In our series, at the end of the follow-
up period, 14 patients (63.6 %) were graded as
excellent, 8 (36.3 %) as good.
In most POD patients, healing and new
bone formation leads to eventual bony fusion.
The process from active destruction to fusion
takes from 6 months to 2 years (7,22,25).
Regarding the conservative treatment, in the
major reported series, the fusion rate varied
between 50% and 100% (7,18,22,26,65).
However, in the present study, 13,6 % of the
patients had complete fusion. Paradoxically,
this low fusion rate may be directly related to
HBO2 therapy, and may explain its efficacy; it
is commonly accepted that prompt diagnosis
and appropriate treatment in these cases is
capable of shortening its course and reducing
severe sequelae (2,4,16,19,22,27,38,42), and
also some authors reported that antibiotics were
unable to arrest the progression of discitis once
it had been established (18,41,65).
CONCLUSION
Although the number of patients is
small to make any definite conclusions, this
study represents the first series of cases in
which HBO2 therapy was used as an adjunct
to treat POD. Our preliminary results indicate
that HBO2 therapy is a safe, effective, and
noninvasive adjunctive treatment modality
in the management of postoperative discitis.
Radiologic and serologic consolidation was
obtained earlier and clinical outcome was more
pleasant in terms of hospital stay, duration of
immobility, pain relief. The length of time
on antibiotics and the need for long-term
hospitalization can be shortened with the use
of HBO2 as an adjunctive treatment; therefore,
it also seems cost-effective compared to other
treatment modalities without HBO2 therapy
which usually require use of antibiotics and
hospital stay for a longer time. We think that
HBO2 therapy accelerated the healing processs
in the disc space and adjacent vertebra, which
is normally very prolonged due to slow local
metabolism, and prevented progression of bone
destruction, leading to low fusion rate. Our
clinical experience regarding HBO2 treatment
dose and duration indicates that infection
control and establishment of the healing process
can be quite rapid and many patients continue
to exhibit improvement after cessation of HBO2
therapy.
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Figure 2 - a, b, c, d, e, f, g, opposite
Fig. 2-a Fig. 2-b
Fig. 2-c Fig. 2-d
Fig. 2-e Fig. 2-f
Fig. 2-g
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Legend to Figure 2, opposite page
Fig 2. Typical MRI appearance of acute postoperative discitis in a 22-year-old man, 3 weeks after surgery. T1-
weighted sagittal image demonstrating decreased signal intensity at the L5-S1 intervertebral disc space and adjacent
L5-S1 vertebral bodies (A), and intense enhancement after administration of gadolinium-DTPA (B). On T2-weighted
sagittal imaging, high signal intensity is seen in the vertebral bodies and involved disc space (C). Corresponding T1-
weighted axial image after contrast enhancement showing hyperintense adjacent soft tissue and abscess formations in
the anterolateral paravertebral space (D).
T1- weighted (E) and T2- weighted (F) sagittal MRI images obtained after completion of the therapy (one month
after diagnosis) showing decreased T1-weighted and increased T2-weighted signals respectively, in 1/2 of the L5-S1
vertebral bodies (comparing with the Figure.2 A and C, approximately 50% decrease in bone marrow edema is noted)
On follow-up at 6 months T2- weighted sagittal (G) MR images is still demonstrating abnormal signal on either side
of the L5-S1 disc space, despite complete relief of symtoms.
Figure 3 a, b, c, d, e, f, g
Fig. 3-a Fig. 3-b Fig. 3-c Fig. 3-d Fig. 3-e
Fig. 3-f Fig. 3-g
Fig. 3. MR images of 32-year-old man with L5-S1 herniated disc who developed discitis after laminotomy and disc
excision. T1-weighted sagittal MRI (A) demonstrates decreased marrow signal intensity above and below the involved
disc space. After administration of gadolinium-DTPA, enhancement of the bone marrow and intervertebral disc space
can be seen (B). Corresponding T2-weighted sagittal MR image (C) shows increased marrow signal intensity in the
same distribution, as well as increased signal intensity within the disc space. T1-weighted (D) and T2-weighted (E)
sagittal MR images obtained six months after completion of the therapy showing regression of the above findings.
On follow-up at 12 months, T1-weighted (F) and T2-weighted (G) sagittal MR images demonstrating disc space
narrowing and resolution of the infectious process.
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Table 2 Comparison of data obtanied from the study to the available present data in
the literature
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