Procedure-Related Complications (Inadvertent Dural Tear, CSF Leak)

Abstract

Unintended durotomies and cerebrospinal fluid leaks are a known complication of spine surgery with an incidence of 0.3% to 35% reported in the literature. Unintended durotomies may be complicated by postural headaches, pseudomeningoceles, meningitis, nerve rootlet entrapment, arachnoiditis, or postoperative wound dehiscence and infections. Older age, severe spinal stenosis, revision surgery, and synovial cysts are some of the risk factors for unintended durotomies.

The overall reported incidence of unintended durotomies for all spine surgery is 3.1% with retrospective series reporting a 1% incidence for cervical surgeries, 7.6% incidence for index lumbar surgeries, and incidence for revision lumbar surgeries ranging from 8.1% to 15.9%. As in the thoracic spine, ossified posterior longitudinal ligament (OPLL) is the biggest risk factor for dural tears in the cervical spine, and patients with OPLL are 13.7 times more likely to have a durotomy than patients without OPLL.

Direct primary suture repair is a widely accepted option for durotomies with the goal of obtaining a closure that is strong enough to withstand the intrathecal pressure during Valsalva maneuvers while the defect heals.

The use of bedrest in the management after unintended durotomy continues to evolve and varies from no bedrest to a short period of bedrest of 24 to 48 hours. There is a trend of no bedrest with early mobilization if the durotomy is completely closed.

Keywords

durotomy, CSF leaks, CSF tears, OPLL

Highlights

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Unintended durotomies are a known complication of spine surgery with the lowest incidence reported in the cervical spine and the highest in the thoracic spine for decompression of ossified posterior longitudinal ligament.
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Revision spine surgery, older age, and synovial cyst are significant risk factors for dural tears.
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Primary dural defect repair during the index procedure with augmentation has the highest success rate in the cervical and lumbar region, but the thoracic spine benefits from additional temporary cerebrospinal fluid diversion.

Background

Unintended durotomies and cerebrospinal fluid (CSF) leaks are a known complication of spine surgery with an incidence of 0.3% to 35% reported in the literature. CSF leaks after spine surgery have been estimated to increase the hospital stay cost on average by 50.4% with reimbursement increased only 21%, based on a prospective study from Germany. Patients with CSF leak have been reported to cost the US healthcare system an additional $6479 compared with spine surgery patients who did not have any CSF leak complications. Unintended durotomies may be complicated by postural headaches, pseudomeningoceles, meningitis, nerve rootlet entrapment, arachnoiditis, or postoperative wound dehiscence and infections. Older age, severe spinal stenosis, revision surgery, and synovial cysts are some of the risk factors for unintended durotomies. A prospective study of 1741 patients undergoing index lumbar spine fusion surgery assessed for the effects of inadvertent durotomy on patient-reported outcomes and postoperative complications. There was no significant difference found in postoperative infection, need for reoperation, or symptomatic neurologic damage in this population where the durotomy was recognized and addressed intraoperatively. Additionally, there was no difference in the final reported outcomes of back pain, leg pain, or functional disability.

Anatomic Insights

In a retrospective study examining the pathologic anatomic variance that increased the risk for unintended durotomies, Takahashi et al. found that in discectomies, the durotomy usually occurred near the nerve root at the disc level. In degenerative spondylolisthesis, the durotomy often occurred at the medial facet or the rostral aspect of the inferior lamina, and in lumbar stenosis without spondylolisthesis, the durotomies occurred at the medial facet and the caudal aspect of the superior lamina. In those patients with synovial cysts, the dural tears occurred wherever the lesions made contact with the dura.

Red Flags

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Signs of CSF egress are pulsatile clear fluid coming from a dry field or the swirl of lighter fluid with a bloodier border.
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Repeat bleeding from areas that previously were controlled should raise the concern that there has been CSF loss with thecal sac decompression or that an occult dural tear is possible.
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Postoperative postural headaches should be investigated as a sign of a CSF leak.
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A subfascial drain with consistently high output over several days with stable hemoglobin/hematocrit should prompt investigation for an asymptomatic CSF leak, and the fluid should be sent for Beta-2 transferrin.

Unintended Durotomies After Thoracic Decompression

CSF leaks after thoracic surgery for decompression are more frequently reported in the literature compared with after lumbar spine surgery, ranging from 20% to 30% with most cases attributed to ossified posterior longitudinal ligament (OPLL). Dural violation may seem inevitable in patients with OPLL since the dura was found to be ossified in 25% of the cases reported by Sun et al.

Incidence and Risk Factors

The overall reported incidence of unintended durotomies for all spine surgery is 3.1% with retrospective series reporting a 1% incidence for cervical surgeries, 7.6% incidence for index lumbar surgeries, and incidence for revision lumbar surgeries ranging from 8.1% to 15.9%. As in the thoracic spine, OPLL is the biggest risk factor for dural tears in the cervical spine, and patients with OPLL are 13.7 times more likely to have a durotomy than patients without OPLL. Revision cervical surgery was the second most common risk factor for CSF leak in this series. Synovial cyst adhesion is another leading cause, as is advanced patient age. In a prospective study by Baker et al., multivariate analysis demonstrated that revision surgery patients were 2.21 times more likely to have an unintended durotomy than patients undergoing primary spine surgery. Other mechanisms of unintended CSF leaks that can occur postoperatively include dural sac laceration or puncture from residual bone spicules or postoperative infection that may degrade a primarily repaired durotomy.

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