Key-words: Intradural tumor - minimally invasive surgery - spinal tumor - tubular retractor
Introduction
Laminectomy is the most commonly performed approach for excision of the intradural
spinal tumor. Conventionally, intradural spinal tumor excision requires longer skin
incision, bilateral subperiosteal muscle stripping, and total laminectomy. Hence,
it decreases the stability of the spine and increases the morbidity.
Unilateral hemilaminectomy is a good corridor for the removal of intradural extramedullary
spinal tumors. This approach offers the advantage of less postoperative pain and no
postoperative deformity.[[1 ]] As the field of minimally invasive surgery (MIS) has developed, it has been implemented
for the treatment of increasingly difficult and complex pathologies, including trauma,
spinal malignancies, and spinal deformity in adults.[[2 ]] MIS for the resection of intradural extramedullary tumors is safe and effective
and offers a reduction in operative blood loss, lower risk of cerebrospinal fluid
(CSF) leak, and shorter hospital stay for select patients.[[3 ]]
Intradural extramedullary and extradural tumors can be completely and safely resected
through a minimally invasive approach using the nonexpandable tubular retractor.[[4 ]] Most common intradural tumors are schwannomas and meningiomas. The authors analyzed
the surgical technique and outcome of the thoracic and lumbar intradural spinal tumor
excision using minimally invasive tubular retractor system.
Patients and Methods
The study was conducted in the Department of Neurosurgery, Government Medical College,
Thrissur, India, and approved by the Institutional Review Board of the institution.
The authors retrospectively analyzed prospectively collected data of 13 patients with
thoracic and lumbar intradural spinal tumors, who had undergone hemilaminectomy and
tumor excision using minimally invasive tubular retractor system, between January
2017 and October 2018. Patients satisfying the inclusion and exclusion criteria were
selected. Intradural tumors involving one or two vertebral levels were included in
the inclusion criteria. Intramedullary spinal tumor, intradural tumor extending into
intervertebral foramen, and intradural tumor involving more than two vertebral levels
were considered for exclusion criteria. Preoperative diagnosis of the tumor was done
using 1.5-Tesla gadolinium-enhanced magnetic resonance imaging (MRI). Preoperative
anteroposterior and lateral X-ray of the thoracic or lumbar spine was taken in all
the cases. Computed tomography scan was taken in few cases. All the patients underwent
surgery using expandable or nonexpendable tubular retractor system. Tubular retractor
system of either Jayon (India) company or PITKAR (India) company was used depending
on the availability. For single-level spinal tumor, it was the preference of the neurosurgeon
to use expandable or nonexpendable retractor system. For two-level spinal tumor, only
expandable tubular retractor system was used. Tubular retractors of various diameter
and length were available. Preoperative, intraoperative, and postoperative parameters
were analyzed.
Parameters analyzed
The parameters analyzed include age, sex, pain using visual analog scale (VAS), power
using Medical Research Council (MRC) grading, myelopathy using Nurick's grade, sensory
changes, bowel and bladder symptoms, spinal tumor level, size of the tumor, side of
the tumor in spinal canal, skin incision length, tubular retractor type and diameter
used, hemilaminectomy side and level, intraoperative blood loss, intraoperative extent
of tumor resection (gross total/near total), dural closure technique (primary/secondary),
dural suturing technique (continuous/interrupted), suture material used for dural
closure, use of fibrin glue, duration of surgery, and histopathology. Complications
noted include skin necrosis, surgical site infection (SSI), CSF leak, pseudomeningocele,
intraoperative wrong level, and intraoperative conversion to open surgery. The postoperative
outcomes which were assessed include changes in sensory symptoms, VAS, MRC grading,
and Nurick's grade. Changes in urinary and bowel symptoms were noted. Findings in
spine X-ray (anteroposterior and lateral) taken in the postoperative period were noted.
The timing of mobilization and discharge from the hospital were recorded. Any other
complications whether intraoperative or postoperative occurring during the admission
period were recorded. The data for the study were collected from medical records of
the patients available in the medical records library and in the Neurosurgery department.
Surgical videos of the patients were also analyzed.
Operative technique
Preoperative marker X-ray was taken in all the patients to decide for the site of
skin incision. Urinary catheter was inserted before surgery. All the patients were
operated in prone position under general anesthesia with endotracheal intubation.
Radiolucent operation table was used for facilitating the anteroposterior and lateral
C-arm image. Intraoperative neurophysiological monitoring was not used in any case.
After confirming the incision site using C-arm image, a vertical skin incision was
placed in paramedian position around 1.5 cm from the midline. The side of the skin
incision was determined by the side of the maximum bulk of the tumor in MRI scan.
Subcutaneous plane was dissected and thoracolumbar fascia was incised vertically.
Smallest dilator was docked on the hemilamina. Serial dilators were sequentially inserted
over the smaller dilator [[Figure 1 ]]. The dilators were moved over the hemilamina to separate the muscles from the underlying
lamina. The position was confirmed using anteroposterior and lateral C-arm image.
The desired tubular retractor (expandable or nonexpendable) was placed over the largest
positioned dilator [[Figure 2 ]]a,[[Figure 2 ]]b,[[Figure 2 ]]c. Then, all the dilators were removed. The shortest length tubular retractor which
can fit to just above the skin level was used. Longer length tube was avoided since
it was increasing working distance for the instruments. The tubular retractor was
angulated according to the need and fixed to the table-mounted retractor holder [[Figure 3 ]]. The retractor holder can be loosened at any time to reposition the tubular retractor.
Now, the position of the retractor was again confirmed using C-arm image. Neurosurgical
operating microscope (Leica F40) was now brought into the scene. The remaining minimal
muscles over the hemilamina were removed. Hemilaminectomy was done using high-speed
drill (Anspach, Johnson & Johnson) and Kerrison punch. Ligamentum flavum was excised.
Spinous process, interspinous, and supraspinous ligaments were preserved. Whenever
required, the base of the spinous process was drilled for the wider exposure. Minimal
facetectomy was done, whenever required to expose the tumor. Bayonetted instruments
were used to avoid visual obscuration during surgery. Dura was opened longitudinally
using No. 11 scalpel blade and held widely separated using tack sutures, which are
put using 5-0 polypropylene. Arachnoid was opened. The spinal cord, roots, and tumor
were identified. Tumor capsule was opened and tumor was decompressed. Ultrasonic aspirator
(CUSA, Integra, Inc.) was used whenever required. After decompression, capsule was
removed. Small schwannomas were removed en bloc without decompression. In meningioma,
excision of the tumor and coagulation of the dura was considered as the gross total
resection (GTR). Small part of the tumor inseparable from the root or cord was left
behind in near-total resection (NTR). Dura was sutured using continuous or interrupted
sutures. Dural closure was a difficult step. The authors used bayonetted toothed forceps
and bayonetted needle holder for suturing the dura. Fat pieces were layered and fibrin
sealant (Tisseel, Baxter, India or Evicel, Johnson and Johnson) was applied. Tubular
retractor was removed. Separated muscles were reapproximated. Subcutaneous sutures
put and skin stapled.
Figure 1: Serial dilators were sequentially inserted over the smaller dilator in minimally
invasive surgery surgery
Figure 2: (a) Jayon (India) expandable tubular retractor. (b) PITKAR (India) nonexpandable
tubular retractor. (c) PITKAR (India) expandable tubular retractor
Figure 3: The tubular retractor was fixed to the table-mounted retractor holder
Results
There were 13 patients with thoracic and lumbar intradural spinal tumors, who underwent
surgery using minimally invasive tubular retractor system, and satisfied the inclusion
and exclusion criteria. The histopathology of these cases was meningioma (7), schwannoma
(5), and neurenteric cyst (1). Among them, one case of 22-year-old female meningioma
at T9–10 level was converted to open laminectomy. It was arising from the dorsal and
lateral surface of the dura mater. Spinal cord was not visualized due to the dorsal
attachment and increased bleeding from the meningioma. Hence, this case was converted
to open laminectomy and excision. The data were analyzed in the remaining 12 patients.
There were 5 men and 7 women with age group of 27–70 years (mean age: 48 years). There
were 8 thoracic and 4 lumbar tumors. The duration of symptoms was ranging from 2 days
to 72 months (mean: 35 months) [[Table 1 ]].
Table 1: Distribution of age, sex, and duration of symptoms in 12 patients undergoing minimally
invasive resection of thoracic and lumbar intradural spinal
Back pain and radiculopathy were noted in 10 patients, sensory symptoms in 12 patients,
constipation in 2 patients, and urinary symptoms in 4 patients. On examination, spasticity
was noted in 3 patients and lower limb weakness was noted in 12 patients [[Figure 4 ]].
Figure 4: Clinical features of 12 patients undergoing minimally invasive resection of thoracic
and lumbar intradural spinal tumors
Eight cases were predominantly occupying on the right side and four cases on the left
side within the spinal canal. The tumor had pushed the spinal cord to the opposite
direction. The side for the surgery was approached from the side of the tumor within
the spinal canal. The incision length was ranging from 25 mm to 35 mm (mean: 28 mm).
We used tubular retractors with diameter ranging from 22 mm to 30 mm (mean: 24 mm).
Expandable retractors were used in 9 cases and nonexpendable in 3 cases. For two-level
hemilaminectomy, the authors preferred to use expandable retractor. The authors used
either Jayon, India, or PITKAR, India, tubular retractor system depending on the availability.
We have not found any significant difference in the usage of both the systems for
one level tumor [[Table 2 ]].
Table 2: Operative findings of 12 patients undergoing minimally invasive resection of thoracic
and lumbar intradural spinal tumors
The tumor size (craniocaudal) was ranging from 9.5 mm to 38 mm (mean: 19 mm). Intraoperative
blood loss was 75–200 ml (mean: 115 ml). GTR was achieved in 8 (67%) cases and NTR
in 4 (33%) cases. Small part of the tumor adhering to the spinal cord and roots were
intentionally left behind in the four cases of NTR. Dura was sutured primarily in
all the cases. Dural closure was done with continuous sutures in 6 (50%) cases and
interrupted in 6 (50%) cases. Polypropylene sutures were used in 10 (83%) cases (5-0
in 5 cases, 6-0 in 3 cases, and 7-0 in 2 cases) and polyglactin in 2 (17%) cases (5-0
in 1 case and 6-0 in 1 case). There was no difference in the result on using continuous
or interrupted sutures. We found that it was easy to put sutures continuously using
7-0 polypropylene. Fibrin sealant was used in 9 cases. Intraoperatively, fibrin sealant
was found to seal the dura along the suture line. The duration of the surgery was
ranging from 160 min to 390 min (mean: 260 min) [[Table 3 ]].
Table 3: Operative findings, histopathology, and duration of hospital stay after the surgery
of 12 patients undergoing minimally invasive resection of thoracic and lumbar intradural
spinal tumors
Pseudomeningocele and CSF leak were noted in one case of T11–T12 laminectomy and schwannoma
excision. In this case, dura was sutured continuously using 6-0 polypropylene and
fibrin sealant was applied. It was subsided after 10 days of conservative treatment.
One patient had SSI, which was treated with antibiotics and resuturing [[Table 4 ]].
Table 4: Complications of 12 patients undergoing minimally invasive resection of thoracic
and lumbar intradural spinal tumors
All the patients were treated with oral acetaminophen 500 mg twice daily for 3 days
and oral gabapentin 100 mg once daily for 2 weeks. Minimal pain was noted at the surgery
site in postoperative period. All the affected patients (100%) were improved in VAS
(preoperative mean: 8.6; postoperative mean: 1.5). Sensory symptom of paresthesia
or numbness was improved in all patients (100%). Nurick's grade was improved in all
3 affected patients (100%). Lower limb power was grossly assessed using MRC grading.
Power was improved in all the affected 12 patients (100%). Ten patients were mobilized
in 24 h. In the remaining two, one patient with preoperative paraplegia started walking
with support on the 6th postoperative day. The other patient with severe lower limb
weakness (right: Grade 2, left: Grade 0) had improved in power (right: Grade 4, left:
Grade 1) without able to walk. Out of 2 patients with constipation, one was improved
but the other developed incontinence, which was recovered on follow-up after 2 weeks.
Out of 4 patients with urinary symptoms, 3 were recovered. However, one patient of
retention was discharged with urinary catheter. Another preoperatively normal patient
developed urinary retention in the postoperative period. On evaluation by urologist,
he was found to have Grade II benign prostatic hypertrophy. Hence, he was discharged
with urinary catheter on urologist advice [[Table 5 ]]. Postoperative anteroposterior and lateral X-ray was showing preserved spinous
process and facet joints. The duration of the hospital stay was ranging from 2 days
to 11 days (mean: 6 days).
Table 5: Preoperative and postoperative clinical findings of 12 patients undergoing minimally
invasive resection of thoracic and lumbar intradural spinal tumors
Illustrative case 1
A 70-year-old female patient presented with a history of walking difficulty and lower
limbs numbness for 4 years. Walking difficulty had gradually progressed. After a trivial
fall 10 days back, the patient had become bedridden and also developed urinary retention
and constipation. Examination revealed the right lower limb Grade 2 power and left
lower limb Grade 0 power. Sensation was decreased in the lower limbs, lower limb tone
was normal, and urinary bladder catheterized. Gadolinium-enhanced MRI scan revealed
contrast-enhancing lesion at T10–11 level arising from anterior and left lateral dura
of the spinal canal. Radiologically, it was diagnosed as a case of meningioma [[Figure 5 ]]a and [[Figure 5 ]]b. The patient underwent surgery in prone position. A 2.5-cm left paramedian incision
was put at T10 lamina level. Serial dilators were placed and the patient underwent
T10 left hemilaminectomy using 22-mm nonexpandable PITKAR tubular retractor system
[[Figure 6 ]]a. The base of the T10 spinous process was drilled. Dura was opened longitudinally.
Arachnoid was opened. Meningioma, cord, and roots were defined [[Figure 6 ]]b. Tumor was removed in piecemeal and gross total excision was done. Anterior and
lateral dural inner surface was coagulated using bipolar diathermy. Dura was closed
using 6-0 polyglactin interrupted sutures [[Figure 6 ]]c. Bone pieces removed during laminectomy were replaced back on the dural surface
along with fat pieces [[Figure 6 ]]d. Fibrin sealant was applied and wound closed in layers.
Figure 5: (a) Gadolinium-enhanced magnetic resonance imaging scan sagittal image showing meningioma
occupying the anterior part of the spinal canal at T10-11 level. (b) Gadolinium-enhanced
magnetic resonance imaging scan axial image showing meningioma occupying the anterior
and left lateral part of the spinal canal at T10-11 level
Figure 6: (a) Visualization of the dura after hemilaminectomy using nonexpendable retractor
system. (b) Tumor and roots were visualized through the tubular retractor system.
(c) Dura was closed using 6-0 polyglactin interrupted sutures. (d) Postoperative computed
tomography scan showing the left hemilaminectomy in minimally invasive surgery for
tumor excision. Bone pieces removed during laminectomy were replaced back on the dural
surface
Illustrative case 2
A 22-year-old female patient was presented with a history of walking difficulty for
1 year, paresthesia and backache for 1 month. Examination revealed the right lower
limb Grade 4 power and left lower limb Grade 5 power. Tone was increased in both the
lower limbs. Gadolinium-enhanced MRI scan revealed contrast-enhancing lesion at T9–10
level arising from posterior and right lateral dura of the spinal canal. Radiologically,
it was diagnosed as a case of meningioma [[Figure 7 ]]a,[[Figure 7 ]]b,[[Figure 7 ]]c. The patient underwent surgery using PITKAR expandable tubular retractor system.
On opening the dura, meningioma was seen arising from dorsal and lateral surface of
the dura. Hence, the spinal cord was not visualized. Furthermore, there was increased
bleeding from the tumor. Hence, the case was converted to open laminectomy and excision
of the tumor.
Figure 7: (a) Gadolinium-enhanced magnetic resonance imaging scan sagittal image showing contrast-enhancing
meningioma occupying the posterior aspect of the spinal canal at T9-10 level. (b)
Gadolinium-enhanced magnetic resonance imaging scan coronal image showing contrast-enhancing
meningioma occupying the posterior aspect of the spinal canal at T9-10 level. (c)
Gadolinium-enhanced magnetic resonance imaging scan axial image showing contrast-enhancing
meningioma occupying the right lateral and posterior aspect of the spinal canal at
T9-10 level
Discussion
Nzokou et al. operated 13 patients with thoracic and lumbar spinal tumors using a
nonexpandable tubular retractor system. There were 4 patients with intradural (2 lumbar
and 2 thoracic) and 9 patients with extradural spinal tumors. There was mean blood
loss of 180 ml and mean operative time of 194 min in intradural tumors.[[4 ]]
Mannion et al. operated on 13 intradural extramedullary tumors using minimally invasive
tube-assisted paramedian oblique approach. Satisfactory tumor resection was achieved
in all but 1 case. Mean blood loss was 155 ml and mean operative time was 180 min.
The surgical incision was inaccurately placed by one level in 2 cases. In 1 case,
the approach was converted to open when the tumor could not be found, and postoperatively,
there was a CSF leak with infection that required readmission.[[5 ]]
Haji et al. retrospectively reviewed 15 intradural and 7 extradural neoplasms in 20
patients operated on between September 2005 and May 2009 using METRx MAST Quadrant
expandable (22–52 mm) tubular retractors (Medtronics). Mean intraoperative time was
210 min, blood loss 428 mL, and average length of hospital stay was 3 days. Four patients
required postoperative patient-controlled analgesia for pain control, and an average
of 5.8 doses of narcotic were given per patient. One patient developed CSF leak and
another patient developed foot drop and urinary retention. About 15 of 22 tumors (68%)
were completely resected, with only one patient requiring repeat operation for residual
tumor.[[6 ]]
Gandhi et al. retrospectively reviewed a prospectively collected surgical database
of 14 intradural spinal tumors operated using expandable retractors. Mean intraoperative
time was 218 min, estimated blood loss was 280 mL, and average length of hospital
stay was 3 days. There was 1 case of wound dehiscence. GTR was achieved in 79% of
cases and patients improved neurologically in 71% of cases.[[7 ]]
Pham et al. reviewed the literature to find all studies involving minimally invasive
resection of intradural extramedullary spinal tumors through the use of a tubular
retractor system. Nine studies were found for a total of 114 patients with reported
mean ages from 46.5 to 63.8 years and follow-up times from 1.5 months to 24 months.
Studies reported their GTR rates (range: 75%–100%), mean operative time (range: 184.9–256.3
min), mean estimated blood loss (range: 56–238.8 ml), and hospital length of stays
(range: 2.4–6.9 days). The most common surgery-related complication was CSF leak or
pseudomeningocele in 6 patients (5.3%) of which 4 patients (3.5%) required a reoperation.
MIS for the resection of intradural extramedullary tumors is safe and effective and
offers a reduction in operative blood loss, lower risk of CSF leak, and shorter hospital
stay for select patients.[[3 ]]
In our study, there were 5 men and 7 women with mean age 48 years. There were 8 thoracic
and 4 lumbar tumors with mean duration of symptoms of 35 months. Eight cases were
predominantly occupying on the right side (67%) and 4 cases on the left side (33%)
within the spinal canal. The mean skin incision length was 28 mm. We used tubular
retractors with diameter ranging from 22 mm to 30 mm (mean: 24 mm). Expandable retractors
were used in 75% of cases and nonexpandable in 25% of cases. The mean tumor size (craniocaudal)
was 19 mm and intraoperative blood loss was 115 ml. GTR was achieved in 67% of cases
and NTR in 33% of cases. Dural closure was done with continuous sutures in 50% of
cases and interrupted in 50% of cases. Polypropylene sutures were used in 83% of cases
and polyglactin in 17% of cases. There was no difference in the outcome on using any
particular suture or suturing technique. We found that it was easy to put sutures
continuously using 7-0 polypropylene. Fibrin sealant was used in 75% of cases. The
authors believe that fibrin sealant reduces the chances of CSF leak. The mean duration
of the surgery was 260 min. Pseudomeningocele and CSF leak was noted in one case.
The authors believe that chance of CSF leak is more in case of long dural incision.
One patient had SSI. One case of dorsally placed meningioma was converted to open
surgery. Minimal pain was noted at the surgery site in postoperative period. Motor
power, VAS, sensory symptoms, and Nurick's grade were improved in 100% of cases. Long-term
follow-up is not available for assessing the development of kyphosis. The mean duration
of the hospital stay was 6 days.
Conclusion
Meningiomas arising from the posterior part of spinal dura are preferably operated
by open technique. Selection of the ideal patient and experience with open surgery
is the paramount factor for the success of MIS tumor excision. Correct C-arm localization
of the level of tumor is the most important step in MIS surgery. Bayonetted-shaped
instruments will help in avoiding the visual obscuration by the instruments during
the surgery. Tumors occupying one spinal level can be operated with either expandable
or nonexpandable tubular retractors. However, two-level spinal tumors will require
expandable tubular retractors. Gross total excision of the anteriorly or laterally
placed intradural tumors confined to the spinal canal can be done safely and effectively
using tubular retractor system, with adding the advantages of the MIS surgery. Longer
length of the dural opening has higher chances of CSF leak. MIS reduces the blood
loss, soft-tissue injury, bone removal, skin incision, and the hospital stay.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms.
In the form the patient(s) has/have given his/her/their consent for his/her/their
images and other clinical information to be reported in the journal. The patients
understand that their names and initials will not be published and due efforts will
be made to conceal their identity, but anonymity cannot be guaranteed.
