An incidental dural tear is a well-known complication in both open and percutaneous lumbar spine surgery. Several techniques have been described for surgical repair of dural tears in open lumbar spine surgery. However, the treatment of iatrogenic dural tears in endoscopic spinal surgery remains challenging. The objective of this report is to describe a technique for endoscopic dural closure using a collagenous patch derived from bovine pericardium (Tutopatch) which is simple and effective.

Keywords: Dural tear, Percutaneous endoscopic lumbar discectomy, Tutopatch

Abbreviations: PELD: Percutaneous endoscopic lumbar discectomy; CSF: Cerebro-spinal fluid; MRI: Magnetic resonance imaging

INTRODUCTION

An incidental dural tear is a relatively common complication of spine surgery. Its prevalence ranges from 1% to 17% in open microsurgical techniques [1]. The incidence of a dural tear in percutaneous endoscopic techniques is considered to be relatively low. In a review of 816 consecutive patients who underwent Percutaneous Endoscopic Lumbar Discectomy (PELD), Ahn et al. reported an incidence of 1.1% [2]. In case of a dural tear in open lumbar spine surgery, several techniques have been described for surgical repair. However, the standard technique of suturing the tear is difficult, if not impossible, in PELD because of the limited working space and the difficulty in handling the surgical instruments within the narrow working channel of the endoscope. In these cases, the surgeon is usually obliged to terminate the endoscopic procedure and convert to open technique to be able to repair the dural tear and prevent its complications.

In this report, we describe a case of incidental dural tear during percutaneous endoscopic interlaminar discectomy that was treated successfully using a collagenous patch derived from bovine pericardium (Tutopatch).

CASE REPORT AND TECHNICAL NOTES

A 45 years old male patient presented with a large, left-sided, L5-S1 disc herniation associated with bilateral pars defect and low grade spondylolisthesis resulting in severe radical pain in the left leg that failed to respond to conservative treatment (Figure 1). Dynamic X-rays of the lumbar spine did not show significant movement of L5 over S1 (Figure 2). 

Surgical options were discussed fully with the patient including the possibility of fusion and instrumentation at L5-S1 level. Patient elected to undergo percutaneous endoscopic discectomy to relieve his sciatic pain and delay fusion at this level. The procedure was done in the prone position under general anesthesia using the interlaminar approach from the left side. After removal of the herniated disc fragments, a dural tear affecting the S1 nerve root sleeve was noted in Figure 3. Because of the inability to suture the dura of the nerve root and in order to avoid conversion of the procedure to open surgery, a collagen patch derived from bovine pericardium, Tutopatch (Tutogen Medical Gmbh, Industries traBe 6, 91077 Neunkirchen am Brand, Germany) was used to repair the dural tear. Using the regular endoscopic instruments, mainly the endoscopic grasping forceps and a hook probe, a small piece of the patch was cut and inserted through the defect in the dura to seal the tear from within Figure 4 (RTI Surgical, Inc. 11621 Research Circle Alachua, Florida 32615). Another piece of the patch was used to cover the outer surface of the defect. The aim was to prevent rootlets herniation through the dural tear.

The patient was kept on flat bed rest for 24 h after which he was allowed to ambulate freely. He did not report any symptoms related to CSF leakage like headache, nausea, vomiting or neck pain and stiffness. A two-week follow up MRI of the lumbar spine showed no signs related to CSF leakage (Figure 5).

Regular follow up of the patient at 2 weeks, 6 weeks and 3 months showed complete resolution of his symptoms except for mild numbness along the dermatomal distribution of the S1 nerve root.

DISCUSSION

An incidental dural tear is a well-known complication in any spine surgery. Its treatment in open techniques is well described in the literature. However, treatment of dural tears in percutaneous endoscopic lumbar discectomy is still considered a challenging problem, even for highly experienced endoscopic spine surgeons. As the use of this endoscopic technique increases, the risk of having incidental dural tears also increases.

The incidence of dural tears in PELD is relatively low.

Chumnanvej et al. [3] described 60 patients who had full endoscopic lumbar discectomy via interlaminar approach. There were no serious neurological complications or dural tears. Ahn et al. [2] reported on 816 consecutive patients who underwent PELD using the transforaminal approach for treatment of symptomatic lumbar disc herniation. Only nine patients (1.1%) experienced symptomatic dural tears.

Dural tears during PELD might be recognized either intraoperatively or might be missed and diagnosed postoperatively. The postoperative clinical manifestations of dural tears in PELD are different from those of open lumbar discectomy. In open techniques, patients with dural tears usually present with signs and symptoms related to cerebrospinal fluid leakage like postural headache, nausea, vomiting, dizziness and photophobia. In addition, these patients might present with large fluid collection at the surgical site.

However, in PELD, there is no dead space for collection of CSF and as such fluid collection in the wound or CSF leakage through the wound is rare and most of these patients usually present with recurrence of the radicular pain, with or without neurological deficit. According to Ahn et al. [2], these signs and symptoms may be due either to nerve root irritation secondary to exposed nerve rootlets or to nerve root herniation through the dural defect. Patients with nerve root irritation usually present with intractable leg pain without neurological deficit while patients with nerve root herniation usually present with leg pain associated with neurological deficit.

The management protocol of dural tears in PELD has not been well described in the literature. Direct suture repair, like in open surgeries, is technically difficult, if not impossible due to the limited working space. When an iatrogenic dural tear is recognized intraoperatively, the surgeon is usually forced to convert to open technique and perform direct repair under microscopic visualization. Ahn et al. [2] stated that the intraoperative attempt to repair the defect by shielding materials is ineffective and the proper management option is immediate open conversion and direct repair of the dural tear.

However, surgical repair of the dural defect without direct suturing is also a well-known technique in open spine surgery. Several studies in the literature reported good clinical results with dural repair using fat or muscle graft, fascia graft, various sealants materials like fibrin glue, or other closure adjuncts such as dural grafts and patches [4,5,6].

The technique described above is simple and does not require the use of any suturing materials. It entails the use of intradural and epidural patch to repair the dural defect (double-layered duraplasty). Using only an epidural patch will not resist the pressure of a CSF leak. If an intradural patch is added, then the CSF pressure will push the patch against the dural wall defect and prevent any CSF leakage or rootlets herniation. Hence, this method will provide a more watertight dural repair than a one-layer dural patch. In addition, the collagen matrix initiates clot formation, resulting in a chemical seal. It also provides a chemical signal for fibroblasts infiltration which deposit new collagen, thereby reconstituting new dura.

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