Post-operative Pseudomeningocele after Spine Surgery: Rare Cause of Failed Back Syndrome

Background and Importance Lumbar pseudomeningocele is an extradural cystic collection of cerebrospinal fluid with no dural covering. It results from a breach in the dura–arachnoid layer. This rare complication results from a dural rent or dehiscence after laminectomy. The exact cause of postoperative pseudomeningocele incidence is unknown and is usually under reported, as most of these patients remain asymptomatic (1). The other possible reason for under reporting may be reluctance on part of the operative surgeon. Diagnosis of this rare entity is reached on a post-operative magnetic resonance imaging scan. We came across two post-laminectomy patients with symptoms of low back pain, radicular pain and swelling over the operative site in past one year. An MRI scan was performed in these patients which revealed the presence of a pseudomeningocele at the site of previous surgery. Both patients were managed with reexploration and surgical closure of the dural defect. Patients showed improvement in symptoms post operatively. This prompted us to revisit pseudomeningocele as a possible cause of failed back syndrome with its literature review. Case presentation Failed back syndrome or post-laminectomy syndrome is increasingly observed by surgeons in clinical practice due to the large number of spine surgeries being performed. The common cause of this often cited entity can be persistent disc herniation, post-operative infection, post-operative fibrosis or improper spinal instrumentation and fusion. Traumatic pseudomeningocele is an uncommon and rarely seen complication following spine surgery, and may be a cause of failed back syndrome in some symptomatic patients. We routinely came across numerous operated patients with persistent symptoms of low back nd radicular pain. These patients should undergo a thorough clinical and radiological evaluation to determine the cause of their symptoms. We came across two patients with post-operative pseudomeningoceles in the past year. A literature review was done to determine the incidence of this entity and its optimal management. CASE 1 A 29-year-old male presented with complaints of low back pain and progressive fluctuating swelling over the operative site (Figure 1). There was associated low back and radicular pain over both lower limbs for last 6 months. The patient had history of having undergone a right sided keyhole L4 laminotomy with microsurgical excision of a filum terminale dermoid cyst with detethering of low-lying cord 10 months ago. The patient gave history of an uneventful postoperative period. Immediate post-operative MRI scan did not reveal evidence of any cerebrospinal fluid (CSF) collection or residual tumor (Figure 2). Repeated MRI scan revealed the presence of a 8.1×6.1×5.6 cm lobulated CSF intensity collection overlying the laminotomy defect opposite L4 vertebral body (Figure 3). The collection was extending craniocaudally from L3 to L5 level and anteroposteriorly from subcutaneous plane to dorsal aspect of thecal sac. The patient was diagnosed as a case of giant lumbar pseudomeningocele. He was initially managed with a lumbar drain for four days. The swelling subsided on lumbar drain insertion and reappeared on closing the drain. In view of established communication between the dura and D ow nl oa de d fr om ir jn s. or g at 1 2: 34 + 03 30 o n T ue sd ay O ct ob er 1 7t h 20 17 [ D O I: 10 .1 88 69 /a ca dp ub .ir jn s. 2. 1. 15 ]