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|NI FEATURE: CENTS (CONCEPTS, ERGONOMICS, NUANCES, THERBLIGS, SHORTCOMINGS) - COMMENTARY
|Year : 2019 | Volume
| Issue : 4 | Page : 1082-1085
Give an Inch and Get a Mile – Simple Modification in the Pial Stay Suture Technique for Intramedullary Spinal Tumors
Arun Kumar Srivastava, Deepak Khatri, Kamlesh Singh Bhaisora, Kuntal Kanti Das, Ved Prakash Maurya, Sanjay Behari
Department of Neurosurgery, SGPGIMS, Lucknow, Uttar Pradesh, India
|Date of Web Publication||10-Sep-2019|
Prof. Arun Kumar Srivastava
Department of Neurosurgery, SGPGIMS, Raibareily Road, Lucknow, - 226 014 Uttar Pradesh
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Srivastava AK, Khatri D, Bhaisora KS, Das KK, Maurya VP, Behari S. Give an Inch and Get a Mile – Simple Modification in the Pial Stay Suture Technique for Intramedullary Spinal Tumors. Neurol India 2019;67:1082-5
|How to cite this URL:|
Srivastava AK, Khatri D, Bhaisora KS, Das KK, Maurya VP, Behari S. Give an Inch and Get a Mile – Simple Modification in the Pial Stay Suture Technique for Intramedullary Spinal Tumors. Neurol India [serial online] 2019 [cited 2020 Jul 4];67:1082-5. Available from: http://www.neurologyindia.com/text.asp?2019/67/4/1082/266240
The surgery for intramedullary tumors (IMTs) has always been challenging. Mild to moderate neurological deficits with functional morbidity are commonly observed, even with the best of surgical hands working at well-equipped centres.,, Elsberg first reported the surgical excision of IMT more than a century ago; however, postoperative morbidity still looms large among these patients. Recent advancements in neurosurgery such as improved optics of the operating microscope, electrophysiological monitoring, intraoperative ultrasound and ultrasonic aspirator have undoubtedly influenced the surgical outcome positively, but a meticulous surgical technique still remains the key. Most of the IMTs are benign and encapsulated, usually affecting young adult individuals. Thus, a complete safe excision with good functional outcome promises a lot to the patient, hence to the society at large. Over the years, we have observed that good intraoperative visualization and surgical ease in handling such tumors are the two most important factors influencing the outcome. Here, we describe a simple modification in the pial stay suture technique, which helped us to gain a wide exposure and much better visualization of the tumor–cord interface as comparison to the conventional technique.
| » Surgical Technique|| |
The operative spinal level is identified and a laminotomy or laminectomy is performed. The duramater is opened in the midline [Figure 1]. The edges of duramater are retracted with stay sutures using 4-0 vicryl (20 mm, ½ circle) and clipped with drape sheet on the side of the incision line for a relatively rigid stay [Figure 2]. At first, a myelotomy is done superficially using an arachnoid knife (we use 24-gauze needle mounted on a Bard-Parker handle) cutting through the remaining four layers of meninges [Figure 3] followed by a deeper myelotomy incision depending on the nature of the tumor with a No. 15 surgical knife.
|Figure 1: Simple Line diagrams showing a transverse cut section at the level of tumor prior to laminectomy (a) displaying lamina (1), duramater (2), arachnoidal layer (3), epipial/pial layer (4) & intra-medullary tumor (5); after the laminectomy is performed (b). A midline durotomy is performed and dural edges are help apart using stay suture. (c) Our novel modification of the pial stay suturing technique with enmasse suturing of the dura, arachnoid & epipial/pial layers. It results in a wider exposure of the tumor with better visualization angle (d)|
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|Figure 2: Operative photograph showing the vital importance of initial stable dural tucking prior to taking the composite suture|
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|Figure 3: A labelled diagram showing a transverse cut section of normal cord with overlying meningeal layers. (1) Duramater, (2) Piamater, (3) Leptomeningeal layer, (4) Epipial layer and (5) Pial layer|
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We have used 5-0 vicryl (16 mm ½ circle) suture in our technique. We use an “outside-in technique” where the needle is first taken through the duramater edge leading into the arachnoid edge along with the intermediate leptomeningeal layer and cut end of the epipial/pial layers, or sometimes even through the tumor capsule to further protect the cord substance and holding it back with the help of a small hemostatic forceps. We strictly avoid dissection of the subarachnoidal plane. “Inside-to-outside technique” where suture is taken in vice versa manner may also be used, depending on the dexterity of the surgeon. The leptomeningeal layer and cut edges of the epipial and intima pial layers remain co-apted together and therefore are not appreciated as separate layers under the operating microscope. The epipial layer is what we appreciate well after median myelotomy.
We have operated 23 patients (cervical 7, cervicothoracic 4, thoracic 6, thoracolumbar 5, lumbar 1) using this technique. An illustrative operative video is attached as supplementary material [Video] for a better understanding of our pial suturing technique.
| » Discussion|| |
A meticulous surgical technique with adequate exposure of the critical areas during IMT surgery can never be overemphasized. Our modification in the pial suturing technique is very simple, yet highly effective in this regard.
As most of the IMTs arise dorsally, a posterior midline myelotomy is done to gain surgical access. However, these tumors often distort the normal anatomy of the cord, and therefore identifying the midline is a crucial operative step. Midline can be identified and confirmed using anatomical landmarks or ultrasonography. In our experience, all forms of electrocauterization were strictly avoided while performing the myelotomy to preserve the superficial vasculature of the cord. We have observed that such minimal bleeding can be very easily controlled with warm saline irrigation and placing a cottonoid.
A conventional myelotomy yields an exposed cord surface similar to two triangles abutting at a common base (b) with a total surface area measured mathematically as SA(c) = 2 × area of triangles = 2 × ½ b × h, where h is the height of one triangle or half the length of the myelotomy made. With this technique, we have noticed a gain in the width of the myelotomy twice when compared with the conventional approach. Keeping the length of myelotomy the same as previous, the surface area now would equal to SA(N) = 2 × ½ × 2 b × h = 2 SA(c). It simply translates into a gain in exposed intramedullary surface area by 100%!!
In addition, the angle of exposure opens up significantly from an acute angle to obtuse angle and helps in early visualization of the tumor–cord interface [Figure 4].
|Figure 4: Spinal cord with intact arachnoidal layer (a) Exposed surface of the intra-medullary tumor. (b) A conventional myelotomy yields the cut-open cord surface similar to two triangles abutting at a common base. (c) Exposed tumor surface area may be measured mathematically as sum of these two triangles with base (b) and height (h), h=height of one triangle or half the length of myelotomy. With our technique, we have noticed a gain in the width of myelotomy twice (2b) as compared to the conventional approach. (d and e) Early visualization of tumor-cord interface at better viewing angles. (f)|
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We noticed fairly good functional outcome in our patients which is comparable to other studies on IMT excision.,,,, Also, dorsal IMT had poor outcomes when compared with cervical or lumbar region despite their benign histopathological behaviour [Table 1], [Table 2], [Table 3]. Perhaps the inherent anatomical vulnerabilities such as a less roomy thoracic canal diameter along with a precarious blood supply of the dorsal cord may have some role to play in poor surgical outcome.,
This simple modification in the suture technique buttresses the delicate pia and myelotomy edges against the firm duramater thereby providing a more uniform distribution of the traction among the meningeal layers. Moreover, the vector of traction force in our technique routes through the duramater which quite easily bears the majority of traction loads unlike the conventional technique where such traction load is borne by the pia/epipial layers solely. Such reinforcement minimizes the chance of myelotomy edge cut-through while doubling the area of tumor exposure. We have encountered cut-through of this holding suture very rarely (n = 2, 1.5%) in early phase of our experience. The fact that the pial stitch extends only till the dural edge vis-à -vis the conventional pial stitch that extends unsupported till the muscle/fascia or the skin drapes perhaps also contributed to the stability of the sutures. However, utmost caution should be taken to avoid excessive traction on the cord. We used dynamic retraction on these stay sutures to prevent cord injury.
Postsurgical arachnoid scarring is an annoying problem, frequently observed in cases of intramedullary astrocytomas and vascular ependymomas.,,,, By abutting all meningeal layers against the dura, this technique prevents subarachnoid seepage of blood and tumor fluids which perhaps prevents the scarring of arachnoid layer. None of our patients showed clinicoradiological features of arachnoiditis. However, a definite evidence can be documented only upon re-surgery/re-exploration of the operative field, which fortunately did not happen in our experience.
An additional needle prick on the duramater for the pial stay suture may seem to increase chances of cerebrospinal fluid (CSF) leakage. However, only 1 out of our 23 patients developed a pseudomeningocele which led us believe that such prick points with a 5-0 suture needle remain innocuous at large and generally get included in the dural closing sutures. Moreover, our practice of leaving the locally available blood coagulum as an additional layer over the suture line with gel foam buttressing perhaps took care of the same. Thus, there are no additional risks of CSF leak with our technique.
An obvious superiority of this technique has been noticed in terms of exposure and ease of tumor dissection; however, further prospective studies in this regard would be of great interest.
| » Conclusion|| |
Keeping the functional outcome preservation in mind, maximal safe resection of spinal IMT still remains a daunting challenge for the neurosurgical community. All neurosurgical advancements in this regard come together to focus on the single motto – to gain a wide surgical exposure and unhindered visualization of the tumor–cord interface. Our modified pial suturing is a simple, easily reproducible, and cost-effective step in this direction. We believe this technique is effective enough for adoption by the neurosurgical community on a larger scale.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| » References|| |
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3]