Iatrogenic Lumbar Arachnoid Cyst Fenestration for Tethered Cord: 2-Dimensional Operative Video

Iatrogenic lumbar arachnoid cysts are a rare occurrence after intradural surgery.^1,2 To our knowledge, there is only 1 other previous case reported in the literature contributing to a symptomatic tethered cord.³ We present a surgical video (Video 1) demonstrating the history, preoperative workup, and operative technique for exploration and fenestration of a symptomatic iatrogenic lumbar arachnoid cyst with a tethered cord. The patient is a 57-year-old female with a history of a closed neural tube defect with a lipoma that was resected over 20 years before her evaluation. She was lost to follow-up and did not retain any previous medical documentation. She complained of a 2-month history of progressive bilateral lower extremity weakness, leg pain, and worsening of chronic urinary incontinence. Imaging demonstrated a cystic lesion compressing her conus and cauda equina at the L3-4 level. The risks, benefits, and alternatives were discussed, and the patient elected to proceed with surgery. Intraoperative findings demonstrated a complex multiloculated arachnoid cyst with tethering of the conus. The cysts were dissected from the conus and fenestrated, allowing spontaneous flow of cerebrospinal fluid and conus pulsations. Biopsy of the cyst wall confirmed the diagnosis of arachnoid cyst without neoplastic tissue. Due to the presence of multiple loculations, primary pial closure could not be performed. Thus, a circumferential detethering of the conus was performed to ensure complete decompression of the neural elements. Postoperatively, the patient demonstrated improvement in her bilateral lower extremity pain and weakness. Magnetic resonance imaging was scheduled during routine follow-up at 3 months.