Delayed giant thoracic pseudomeningocele presenting as enlarging painless paraspinal swelling followed by postural dizziness: a case report.

Introduction: Pseudomeningocele (PMC) is an uncommon but recognized complication of spinal surgery. In this report, we present a rare case of delayed thoracic PMC presenting as a progressively enlarging, painless paraspinal swelling followed by postural dizziness, occurring 8 months after thoracic laminectomy performed for thoracic ossification of the ligamentum flavum (tOLF).

Case presentation: A 46-year-old woman underwent T9-L1 laminectomy with posterior instrumentation and fusion for tOLF associated with incomplete paraplegia. During the initial surgery, no dural tear or CSF leakage was identified, including during the Valsalva manoeuvre. MRI at 3 months showed no evidence of PMC. At 8 months postoperatively, she developed a progressively enlarging, painless, fluctuant thoracic paraspinal mass followed by postural dizziness, without postural headache or signs of infection. Cranial MRI showed no evidence of spontaneous intracranial hypotension (SIH), and cardiac and carotid examinations revealed no cause for the dizziness. Revision surgery confirmed a PMC with a 2.0 mm × 2.0 mm dural defect, which was repaired using a dural patch with reinforced fascial closure. At 1-year follow-up, the PMC and postural dizziness had completely resolved, with no evidence of recurrence.

Conclusion: We present an uncommon case of delayed thoracic PMC presenting with an enlarging, painless paraspinal swelling followed by postural dizziness, but without postural headache, 8 months after spinal decompression and fusion for tOLF. Follow-up MRI at 3 months after surgery had shown no evidence of PMC, and there was no antecedent trauma. Cranial MRI showed no imaging evidence of SIH. MRI plays a crucial role in establishing the diagnosis. Given the recognised association between tOLF and intraoperative dural tears, delayed PMC should be considered when a painless, progressively enlarging paraspinal swelling develops after surgery for tOLF, even in the absence of postural headache, worsening paraparesis, or imaging evidence of SIH.