Minimally invasive spinal surgery – interlaminar approach for removal of spinal intradural extramedullary tumors.

Posted by Dr. Thamburaj Dr. Thamburaj
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Spinal intradural extramedullary tumors are generally removed by single or multiple level laminectomies with midline dural incision. Rare cases of delayed postoperative kyphosis and spinal instability may be reduced by unilateral or bilateral microsurgery, causing minimum damage to ligaments and tissues.
We present our experience with treating 18 cases with spinal intradural extramedullary tumors by minimally invasive spinal surgery.

Materials and Methods
18 symptomatic patients with laterally placed intradural extramedullary tumors less than or equal to 3 cm were operated between March 2000 – March 2006. There were 13 males and 5 females.
The size of the tumor was between 2 to 3 cm the histology mostly consisted of Schwannoma, neurofibroma, meningioma. Site of the tumor was between D8 to S1, most commonly at L1- L2


Minimally invasive technique - Definition
•         Small incision
 
•         Minimal dissection
 
•         Widening of interlaminar window on one or both sides.
 
 
Inclusion criteria
1. Symptomatic pts with intradural extramedullary tumors less than or equal to 3 cm.
2. Laterally placed tumors
 
Exclusion criteria
Patients with tumors extending more than one spinal level; in these patients hemi-laminectomy or laminectomy was done.
 
Investigations
All patients were examined with preoperative plain radiography, MRI and a post operative x ray [static and dynamic] at the affected spinal level and Post operative MRI-one patient.
 
 
Surgical technique
Surgery was performed in the prone position.
The affected spinal level was identified with intraoperative fluoroscopy.
A midline 3 cm skin incision was made.
A unilateral/ bilateral approach was followed with subperiosteal muscles dissection on the lamina above and below.
The facet joint joint was spared.
With a small paramedial dural incision the total tumor was removed using microsurgical techniques  Water-tight dural closure was done with 5-0 or 6-0 [ prolene / silk ]



Advantages



Disadvantages
1. demanding surgical skills
2. expertise
3. availability of microscope
4. dural closure difficult
5. time consuming[ sometimes ]
 
 

Conclusions
Minimally invasive spinal surgery is superior to standard laminectomy
Cases in which dural closure was difficult, onlay graft was found to circumvent the problem.
Minimally invasive spinal surgery is cost-effective and patient friendly.
The technique reported in the paper should be used more extensively and extended to other intradural extramedullary tumors.