Keywords
extramedullary - intradural - laminectomy - laminoplasty - thoracic schwannoma - spinal
tumors - unilateral hemilaminectomy
Palavras-chave
extramedular - intradural - laminectomia - laminoplastia - schwannoma torácico - tumores
espinhais - hemilaminectomia unilateral
Introduction
Recently, the growing population and resource shortages have necessitated reducing
surgical treatment costs and shortening hospital stays without compromising care.[1] Implementing safer, more effective modifications of existing surgical methods can
benefit both individual patients and society.[2]
[3]
[4]
The optimal surgical approach to intradural tumors remains controversial, although
the traditional approach for the removal of intradural tumors has been laminectomy.[5]
[6]
[7]
[8]
[9]
[10]
[11]
[12]
[13]
[14]
[15]
[16]
[17]
[18]
[19]
[20]
[21]
[22]
[23] Unilateral hemilaminectomy may provide specific advantages, such as less intraoperative
bleeding, less postoperative back pain, and shorter hospital stays, compared with
laminectomy.[24] In this way, the use of extensive metallic implants, which can cause artifacts in
postoperative radiological images and difficulties in dose adjustment in radiotherapy,
is avoided. However, although unilateral hemilaminectomy can provide a better perspective
at an oblique angle, laminectomy provides a clearer and more accurate view at the
right angle.
Thus, we present a case where a patient with a large intradural extramedullary spinal
mass was surgically treated using a tailored combined approach: single level laminoplasty
combined with multilevel unilateral hemilaminectomy.
Case Description
A 53-year-old female presented with back pain, walking difficulty, and left foot numbness
for one and a half years. On examinations, an ataxic gait, paresis of muscle strength
around +4/5 in the left lower extremity, and hypoesthesia in the left leg and foot
were detected. Gadolinium-enhanced T1-weighted magnetic resonance (MR) imaging of
the thoracic spine revealed a contrast-enhanced intradural extramedullary mass lesion,
∼40 × 15 mm in size, with a cystic component. The tumor extended from the level of
the lower end plate of the T7 vertebral body to the mid-level of the T9 vertebral
body. The mass had significantly compressed the spinal cord and displaced it to the
right side. A small part of the tumor extended into the T8 left neural foramen ([Fig. 1 A-E]).
Fig. 1 Radiological examination of the patient. (A): Preoperative contrast-enhanced T1-weighted
sagittal magnetic resonance (MR) image showing an intradural extramedullary tumoral
mass. (B, C): Preoperative axial T2-weighted and contrast-enhanced T1-weighted MR
images. (D): Postoperative T2-weighted sagittal MR image showing gross total removal
of the tumor. (E): Postoperative contrast-enhanced T1-weighted sagittal MR image showing
gross total removal of the tumor.
Surgical Technique
The patient agreed to undergo the procedure and gave informed, written consent for
the publication of this case report. The patient was positioned on the operating table
in the prone position under general anesthesia. The electromyographic activity was
monitored using a NIM-Eclipse neuromonitoring system (Medtronic Inc, Minneapolis,
USA) during the surgical procedure. A midline skin incision of 6–8 cm was made between
the T6 and T10 vertebral levels. Under a surgical microscope (Leica Mikrosysteme Vertrieb
GmbH, Wetzlar, Germany), using No. 1 and 2 Kerrison rongeurs, the T8 lamina was cut
bilaterally and removed in one piece with its spinous process.
After the dura and arachnoid were opened in the midline, a vascular tumor with a yellowish
cyst in the rostral region became visible ([Fig. 2A, B]). The spinal cord was seen on the right side of the large tumor. After removing
a 2–3 mm portion of the T7 left lamina with a width of 4–5 mm, the rostral pole of
the tumor and the proximal spinal cord could be seen under the dura, but the caudal
pole of the tumor mass was not visible. Therefore, the lumbosacral fascia was additionally
cut on the left side of the T9 vertebral spinous process, and the muscles were dissected
subperiosteally on the left side only. The muscles were retracted using a Markham–Meyerding
hemilaminectomy retractor. A T9 left-sided hemilaminectomy of 8–9 mm in width was
performed using an electric high-speed microdrill (Aesculap Inc., Pennsylvania, USA)
and Kerrison rongeurs. The integrity of the facet joints was always preserved. The
dural opening was then extended caudally until the distal pole of the tumor and the
uncompressed spinal cord were visible in the hemilaminectomy exposure area. The dura
covering the tumor was carefully stripped, and dural tack-up stitches were placed.
Fig. 2 Intraoperative photos. (A): Cyst and bulk of the tumor. (B): After the cyst was punctured,
the rostral spinal cord was seen to be adherent to the tumor mass. (C): The last remnant
of the tumor was dissected from the spinal cord and nerve roots. (D): The intact decompressed
spinal cord was visible after the gross total removal of the tumor.
The spinal cord was observed to be markedly compressed and shifted to the right along
the entire extent of the tumor. The tumor cyst was punctured, and tumoral fluid was
collected and sent for pathological examination with a piece of tumoral tissue for
frozen section. The vascular tumoral tissue was then debulked, dissected, and carefully
detached from the spinal cord and nerve roots using microneurosurgical instruments
and bipolar coagulators. Special suction tubes with round, smooth, atraumatic tips
of various diameters, which could be used as blunt dissectors, were utilized in all
microsurgical manipulations except drilling. Using a Cerullo suction regulatory apparatus
(Aesculap Inc., Pennsylvania, USA), it was possible to work at very low vacuum pressure
during arachnoidal dissection. Gross total resection of the tumor was achieved except
for a small foraminal part of the tumor extending to the T8 left neural foramen, which
was coagulated using bipolar forceps ([Fig. 2C, D]).
The arachnoid and dura were closed with running 6–0 silk sutures watertightly. Several
additional interrupted stitches were needed where slight cerebrospinal fluid leakage
was observed. An adhesive dural allograft (Hemopatch, Baxter Healthcare SA, Zurich,
Switzerland) was placed in this dural section as reinforcement ([Fig. 3A]). The dura was then sealed with Tisseel fibrin sealant (Baxter International Inc.,
Illinois, USA). T8 laminoplasty was performed using titanium miniplates (Osimplant,
Ankara, Turkey) and screws ([Fig. 3B, C, D]). Meticulous haemostasis was achieved, and no drainage tube was placed in the wound.
No electrophysiological decrease or loss was observed during neuromonitoring. The
estimated blood loss was 230 mL, and the surgery lasted ∼4 hours from incision to
closure. The postoperative course was uneventful. Histopathology confirmed a benign
spindle cell schwannoma, categorized as WHO grade 1.
Fig. 3 Intraoperative and postoperative radiological demonstration of the tailored laminoplasty–hemilaminectomy
approach. (A): T8 laminectomy and T9 left hemilaminectomy areas seen after the closure
of the dura. (B): T8 laminoplasty was performed. (C): T8 laminae were fixed using
miniplates and screws. (D): Three-dimensional reconstruction of a postoperative computed
tomography scan.
Discussion
This case report demonstrates that gross total excision of a large intradural extramedullary
schwannoma can be safely achieved using a tailored laminoplasty–hemilaminectomy approach
with minimal metallic implants. In our technique, unilateral hemilaminectomy can be
performed at multiple levels, while laminoplasty is limited to a single level. In
this case, single level laminoplasty and partial hemilaminectomy at two levels were
sufficient for safe exposure. An artistic illustration of this technique is shown
in [Fig. 4].
Fig. 4 Artistic illustration of the tailored laminoplasty–hemilaminectomy approach (sketch
by the corresponding author).
Although intraspinal schwannomas are benign, their rarity makes them difficult to
distinguish from other tumors both preoperatively and intraoperatively, complicating
surgical planning.[25] While spinal schwannomas may recur within the first few years following surgical
resection, 95% of cases do not experience recurrence.[25] However, subtotal resection increases the risk of recurrence, making total resection
the preferred surgical goal.
Numerous surgical techniques and their modifications have been reported for the removal
of intradural tumors, including laminectomy, laminoplasty, split laminotomy, unilateral
hemilaminectomy, unilateral multilevel interlaminar fenestration, and unilateral hemilaminoplasty.[12]
[14]
[21]
[23]
[26]
[27]
[28]
[29]
[30] All of these techniques may have their own advantages and disadvantages when applied
alone. Laminectomy may cause kyphotic deformity and spinal instability.[9]
[27]
[31] At the same time, although laminoplasty is thought to preserve spinal stability
more than laminectomy does, it is still insufficient for preserving the stability
of the spine in the context of a multilevel tumor.[32]
[33]
[34]
[35] The unilateral hemilaminectomy method has been shown to cause less spinal deformity
and instability than laminectomy.[8]
[9]
[24]
[28]
[29]
[30]
[35]
[36]
[37]
[38] Median split laminotomy and para-split laminotomy are techniques that provide surgical
access to the spinal canal by utilizing the elasticity of the annular structures surrounding
the canal.[26] These split laminotomy techniques have been suggested to help preserve spinal stability
and may serve as a viable surgical option for certain multi-level intraspinal tumors
with well-defined borders.[26]
Naturally, there are limitations to the application of minimally invasive techniques.
For example, in para-split laminotomy, a smaller portion of bone is removed compared
with hemilaminectomy; however, to achieve adequate surgical exposure, the bone must
be distracted using a lamina retractor. This process carries a risk of fractures to
the lamina, pedicle, and even the vertebral body.[26] Some surgeons have expressed concern that unilateral hemilaminectomy would be insufficient
to provide adequate surgical exposure and would not allow total removal of the intradural
tumors.[9]
[24] Moreover, they have suggested that a midline myelotomy may not be possible when
approaching intramedullary tumors with hemilaminectomy. Indeed, if hemilaminectomy
is performed on the side of the tumor, the position of the spinal cord under pressure
will not be visible until the final stage of the surgery. If it is performed on the
spinal cord side, then the fragile spinal cord may be exposed to surgical trauma at
the very beginning of surgery.
To address these challenges, combining single level laminoplasty with multilevel hemilaminectomy
may offer a safer surgical approach by mitigating the disadvantages of each technique
when used independently, while still harnessing their benefits. However, it is important
to note that generalizations cannot be made from a single case.
Conclusion
Gross total excision of large intradural extramedullary schwannomas can be safely
performed using a tailored laminoplasty–hemilaminectomy approach, where unilateral
hemilaminectomy can be performed at multiple levels, whereas laminoplasty is limited
to a single level.
