Surgical Management for Non-Traumatic Syringomyelia using Syringo-Subarachnoid Shunt “T-Tube”: An Experience of 6 Cases-Juniper publishers
JUNIPER PUBLISHERS-OPEN ACCESS JOURNAL OF HEAD NECK & SPINE SURGERY
Introduction
The natural history of syringomyelia is highly
variable. In some cases, patients do improve or stabilize without
surgery, while others deteriorate even with aggressive interventions.
Various surgical procedures for the treatment of syringomyelia have been
introduced, including posterior fossa decompression, syringostomy,
syringoperitoneal shunting. But even though satisfactory results have
been reported for most of these procedures, some authors have been
critical of these techniques. Through this paper, we will try to make
our contribution by reporting the results we have got after surgical
management of 6 patients operated for syringomyelia by
syringo-subarachnoid shunt using T-Tube.
Methods
Patients
The mean age of our patients was 55.4 years.
Etiologies of our patients’ syringomyelia are various: only one patient
had post traumatic syringomyelia (6 years after trauma). One has an
idiopathic intra medullar cyst; the four others were previously
surgically managed: 3 for decompression of cervico-occipital hinge, and
one for an intradural meningioma (Table 1). All
patients had motor dysfunction, 4 had sensory disorders, and 3 had
sexual or genital disturbances. About radiologic localizations of the
syrinx, 4 patients had an intramedullar cavitation extending through
cervical and dorsal medulla (Figure 1). 1 patient had bulbomedullary
syringomyelia (Figure 2), and 1 had an intramedullary cyst localized in
front of T1-T2 (Figure 3).
Surgical technique
The used technique for all our patients was a syringosubarachnoid
shunt made through the implementation of
a t-tube. Positioning was strict ventral. We proceed to a
laminectomy followed by a durotomy in front of the widest
portion of the intramedullary cavitation. The arachnoid is
opened by making flecks, through which we carefully introduce
the tip of the catheter at the level of the dorsal groove until the
extraction of CSF out from the syrinx. Finally, the two arms of the
T-catheter are attached to the arachnoid.
Follow up
Only one patient had transitory disturbances of the
proprioceptive sensitivity, followed by a recover of the same
anterior neurologic status. Two patients presented neither
deterioration nor amelioration of motor or sensitive functions.
The 3 other patients improved their preoperative status. This
improvement concerned at most sensitive features. All our
patients had postoperative MRI 6 months after surgery. This
control imaging showed a radiologic improvement defined by a
reduction of the size of the syrinx, found in 4 patients (Figure 4).
Two patients had almost the same radiologic lesions as found on
preoperative MRI.
Discussion
Syringomyelia is a known to be a disorder in which a cyst or
cavitations are formed within the spinal cord. This abnormality
called a syrinx can expand and elongate over time, destroying
the spinal cord [1]. Syringomyelia is associated with numerous
different pathologies, including spinal trauma, craniocervical
anomalies mainly chiari malformations, meningitis, spinal
tumor [2]. The pathogenesis of syringomyelia is still a subject of controversies. The most commonly accepted theory is that
the spinal cord’s cavitation occurs when CSF is forced to get
through the fourth ventricle into the central canal. This may
be the consequence of either a caudally directed pulse wave,
or a pressure gradient at the level of the foramen magnum
[3]. Physiopathological theories has conditioned therapeutic
approaches for syringomyelia and led to the development
of several operative procedures depending on its supposed
etiology and pathogenesis [4]. Posterior fossa decompression
[5], syringoperitoneal shunt [6], syringopleural shunt [7],
myelotomy coupled with lumboperitoneal shunt [8], syringosubarachnoid
shunt [9], and several other techniques, have all
been described with varying success.
Several ancient reports have been considering that the results
of syringo-subarachnoid shunt as disappointing. Among their
arguments to explain this failure were discussed the difficulty
of manipulation of the T-tube with a high risk of medullar lesion
[6,10], and the frequency of shunt obstruction as a result of the
collapse of the syrinx cavity around the shunt tip [4,11]. This
failure was mainly discussed in post-traumatic syringomyelia,
where spinal injury produces numerous abnormalities, such as
subarachnoid adhesions, spinal deformity or stenosis in addition
to the syrinx, limiting the efficiency of any shunting procedure
[12].
The new surgical techniques of implantation of T-Tube have
managed to break out with the anterior shortages [6,10]. In our
new shunting procedure, we inserted just one arm of the T-tube
into the syrinx cavity and located the other arm outside the
cord, in the sub-arachnoid space. Thus, we can protect the cord
from tube rotation, but also have the possibility to easily remove
the tube when necessary, without prejudice on the cord. Also,
we could easily anchor the tube to the dura, and thus prevent
migration resulting in shunt malfunction.
According to several authors [13], the most important
factor in the occlusion of the shunt system is the development
of arachnoiditis and adhesions of the arachnoid around tip of
the shunt tubing. Anatomically [9], the dorsal and ventral spinal
subarachnoid spaces are different. Many trabeculae exist between
the pia mater of the dorsal cord surface and the dorsal arachnoid
membrane; however, there are no arachnoid trabeculae on
the ventral surface. Using the standard technique for syringosubarachnoid
shunting, the dorsal subarachnoid space is the
usual site for distal catheter placement and the anatomy of
this space may contribute to delayed shunt malfunction. In the
modified technique described here, the shunt is inserted into the
syrinx at the dorsal root entry zone and the distal tip is inserted
into the anterolateral subarachnoid space.
The results of our series support the reports claiming the
interest of T-Tube shunt technique. Clinically, 50% of the cases
of our series improved their preoperative status, and 50% kept
the same signs without postoperative worsening. 66% had
radiological improvement with regression of the syrinx; the
others had the same preoperative aspects with no worsening.
We do think that with further technical refinement, we could
reach better clinical and radiological results.
According to our good results, this new technique seems to
be promising in the treatment of non-traumatic syringomyelia.
For post-traumatic syringomyelia, an associated broad release of
subarachnoid spaces is required. The study of a larger series is
necessary in order to a better evaluation of the effectiveness of
this technique.
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