Figure. Magnetic resonance image shows a fluid collection posterior to the thecal sac at the L5-S1 level.
A 43-year-old man presents to the clinic 1-week after undergoing an L5-S1 discectomy with complaints of a worsening headache. He admits to persistent clear drainage from his surgical wound over the last few days. A repeat magnetic resonance imaging (MRI) performed postoperatively (Figure 1) shows fluid collection posterior to the thecal sac at the L5-S1 level. On physical examination of the incision, a clear to serosanguineous appearing drainage without skin erythema is observed.
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Incidental durotomy, or dural tear, is one of the most common complications in spine surgery, occurring in approximately 14% of procedures.1,2 The dura mater can be lacerated or punctured by surgical instruments during spine surgery and cerebral spinal fluid (CSF) can leak into the extradural space.1
Cerebral spinal fluid is formed at a rate of up to 0.6 mL per minute or over 600 mL per day; enough to turn over the total amount of CSF 3 to 4 times a day.1 When a dural laceration is large enough, it is usually immediately recognized during surgery as the wound will continuously fill with clear CSF. However, a small dural tear can go unnoticed before surgical closure.1,2
The most common symptom of a dural leak is a headache when the patient is upright (postural headache caused by CSF hypotension). If a dural tear is recognized intraoperatively, the dura should be closed with a suture or patch. In general, patients with a headache or other symptoms after a dural repair are instructed to lay flat for 12 hours postoperatively before raising the head of the bed 10 degrees per hour. Once the head of the bed reaches 60 degrees and the patient remains asymptomatic then ambulation may begin.2
Signs of a missed dural tear include a headache that is worse when standing, nausea, vomiting, and clear fluid draining from the surgical wound. An MRI should be ordered to confirm the diagnosis of a postoperative delayed dural leak. A radionuclide cisternography can be used to identify abnormal flow and determine the location of the dural leak. If the patient has a symptomatic delayed dural tear, the wound should be explored to find and close the dura tear .1,2
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor in chief of the Journal of Orthopaedics for Physician Assistants.
1. Espiritu MT, Rhyn A, Darden BV 2nd. Dural tears in spine surgery. J Am Acad Orthop Surg. 2010;18(9):537-545. doi:10.5435/00124635-201009000-00005
2. Hassanzadeh H, Bell J, Bhatia M, Puvanesarajah V. Incidental durotomy in lumbar spine surgery; risk factors, complications, and perioperative management. J Am Acad Orthop Surg. 2021;29(6):e279-e286. doi:10.5435/JAAOS-D-20-00210