A dural tear is one of the most common complications encountered in operations on the spine. Its incidence ranges from 1% to 17% [1-9
]. A general belief is that spine surgeons tend to underestimate the frequency of this complication [14
]. Reported risk factors for incurring a durotomy include older age, anatomic variations, revision surgery, thinning of the dura and inexperience of the surgeon [15-17
Dural tears are more common in patients with a history of prior surgery with subsequent development of scar tissue, altered anatomy, poor dissection plans and adherence of tissue to the dura [14-16
]. The decreased dead space created by smaller incisions and a muscle-splitting approach that is used in minimally invasive spinal surgery may cause less potential for persistent leakage of cerebrospinal fluid in cases complicated by durotomy. There is a relative lack of information about the true incidence of dural tears with minimally invasive spinal surgery, and which of the dural tears mandate closure is not clarified yet.
Spinal instrumentation, especially the use of cross-links, may result in more dead space surrounding the dura and may prevent the paraspinal muscles from directly tamponading a dural tear [5
The signs and symptoms of dural tears are caused by a persistent leak of cerebrospinal fluid from the subarachnoid space [16
]. A persistent cerebrospinal fluid leak may result in a chronic pain disorder associated with cranial nerve palsies, radiculopathy and postural headaches [3,18
Clinical manifestations of acquired dural tears may be classified as unintended durotomy during the surgery, pseudomeningoceles and cerebrospinal fluid fistula. Pseudomeningoceles and cerebrospinal fluid fistula are seen postoperatively, while unintended durotomy is seen intraoperatively. The main difference between these is the time of observation which guides the treatment strategy.
According to the literature, recommendations for the treatment of dural tears have included primary repair, closed subarachnoid drainage, grafts consisting of muscle, fat or fascia, blood patches, fibrin- adhesive or cyanoacrylate polymer sealant, application of Gelfoam to the tear and bed rest [6-8,19-23
]. However, there is no distinct treatment guideline according to the etiology in the current literature.
In such cases of large spinal wounds secondary to cerebrospinal fistula or exposed hardware, muscle coverage with paraspinal muscle flaps may become the only tool for providing effective, well-vascularized dural coverage for obliterating dead space [24
A dural tear that is observed during the procedure should certainly be repaired primarily due to the well known risks of cerebrospinal fluid leakage. There is a general consensus that, if possible, the surgeon should perform a primary suture closure [25
]. Adequate exposure of the tear is necessary for the proper repair of the dural tear.
Unrecognized or unrepaired dural tears may stay asymptomatic, but sometimes lead to a pseudomeningocele formation or result in cerebrospinal fluid leak during the postoperative period. The prevalence of these complications remains unknown [5
A postoperative extradural accumulation of cerebrospinal fluid in the soft tissue of the back that extravasates through the dural tear and cerebrospinal fluid fistula can be managed either by direct repair or lumbar-subarachnoidal drainage. Over-sewing of the wounds was also described in the literature [15,25
]; however there is far less data.
A precise evaluation of dermatomal sensation and muscle force of the lower extremities is mandatory. In the cases of existing neurological complications, pseudomeningoceles are surgically explored and nerve roots are gently dissected and then reduced into the thecal sac. The dural tear is then repaired by primary sutures [12
]. Pseudomeningoceles and cerebrospinal fluid fistulas without neurological compromise may be managed traditionally by closed subarachnoidal or lumbar drainage.
In our study of 12 patients, which included 5 pseudomeningoceles and 7 cerebrospinal fluid fistulas, the pseudomeningoceles responded well to lumbar drainage, whereas cerebrospinal fluid fistulas were managed successfully by over-sewing the wound and bed rest for 2 to 4 days.
If the dural tear was detected intraoperatively by the presence of clear fluid emanating from the wound, patients were generally advised to remain flat for 4 to 7 days after surgical repair to reduce symptoms and facilitate healing. Bed rest is thought to reduce the hydrostatic pressure on the repaired dura [14
]. Hodges et al. [26
] showed that patients who had a repaired dural tear during the index procedure did well without bed rest. However there is an absence of data on the necessity of bed rest after dural tears that were treated nonsurgically.
Paraspinal muscles and fascia should always be reapproximated tightly. Otherwise extradural anatomic dead space that is created by surgical procedures leading to the leakage of cerebrospinal fluid may not be obliterated. The relatively significant subperiosteal dissection with resultant lateral muscle retraction can result in a larger dead space into which cerebrospinal fluid can leak after closure. With minimally invasive procedures, the resulting dead space is significantly small.
There are few reports of clinical outcomes after incidental durotomy in the literature. Sin et al. [16
] reported that the overall outcome of the patients would not be affected adversely by the presence of a dural tear. On the contrary, Saxler et al. [1
] reported poorer clinical outcome after surgery in patients with an incidental durotomy.
It is unclear whether the postoperative onset of pseudomeningocele and cerebrospinal fistula require different treatments. Due to the small numbers for this type of analysis, we cannot recommend a preferable method in the treatment of pseudomeningoceles and cerebrospinal fluid fistula.
It is our belief that dural tears were not recognized intraoperatively in our patients due to the small size of the durotomy. The small size of the dural defects might be the reason for our success without surgical intervention. Prompt identification and careful closure of the dural defect at the time of the index surgery should be the treatment of choice.