Microendoscopic Posterior Decompression for Treating Thoracic Myelopathy Caused by Ossification of the Ligamentum Flavum: Case Series

Background and Objectives: Ossification of the ligamentum flavum (OLF) is a relatively common cause of thoracic myelopathy. Surgical treatment is recommended for patients with myelopathy. Generally, open posterior decompression, with or without fusion, is selected to treat OLF. We performed minimally invasive posterior decompression using a microendoscope and investigated the efficacy of this approach in treating limited type of thoracic OLF. Materials and Methods: Microendoscopic posterior decompression was performed for 19 patients (15 men and four women) with thoracic OLF with myelopathy aged between 35 to 81 years (mean age, 61.9 years). Neurological examination and preoperative magnetic resonance imaging (MRI) and computed tomography (CT) were used to identify the location and morphology of OLF. The surgery was performed using a midline approach or a unilateral paramedian approach depending on whether the surgeon used a combination of a tubular retractor and endoscope. The numerical rating scale (NRS) and modified Japanese Orthopedic Association (mJOA) scores were compared pre- and postoperatively. Perioperative complications and the presence of other spine surgeries before and after thoracic OLF surgery were also investigated. Results: Four midline and 15 unilateral paramedian approaches were performed. The average operative time per level was 99 min, with minor blood loss. Nine patients had a history of cervical or lumbar spine surgery before or after thoracic spine surgery. The mean pre- and postoperative NRS scores were 6.6 and 5.3, respectively. The mean recovery rate as per the mJOA score was 33.1% (mean follow-up period, 17.8 months), the recovery rates were significantly different between patients who underwent thoracic spine surgery alone (50.5%) and patients who underwent additional spine surgeries (13.7%). Regarding adverse events, one patient experienced dural tear, another experienced postoperative hematoma, and one other underwent reoperation for adjacent thoracic stenosis. Conclusion: Microendoscopic posterior decompression was applicable in limited type of thoracic OLF surgery including beak-shaped type and multi vertebral levels. However, whole spine evaluation is important to avoid missing other combined stenoses that may affect outcomes.

Microendoscopic Surgery with an Ultrasonic Bone Curette for a Patient with Intraforaminal Stenosis of the Lumbar Spine Due to an Ossification Lesion: A Technical Case Report

Introduction:

We present a rare case with radiculopathy resulting from intraforaminal stenosis of the lumbar spine due to an ossification lesion. Microendoscopic surgery was chosen because of two strong advantages. One was the ease to reach the nerve foramen and ossification lesion and the other was the non-invasiveness at the posterior supporting structures of the spine. Moreover, an ultrasonic bone curette developed for microendoscopic spine surgery was applied. This is the first detailed case report of microendoscopic surgery using an ultrasonic bone curette for a patient with radiculopathy due to intraforaminal free ossification.

Case Report:

A 49-year-old woman born in Japan had complained of severe left leg pain for over 7 months in spite of conservative treatment including selective nerve root block. There was no lumbago, muscle weakness, or loss of sensation in her leg. Plain radiography revealed spondylolytic spondylolisthesis classified as Grade II at L4-L5, but there was no instability on dynamic assessment. Computed tomography (CT) showed a free ossification lesion in the foramen at L4-L5. Considering a diagnosis of left L4 radiculopathy due to the free ossification, ossification resection and nerve decompression were performed with posterior spinal microendoscopic surgery using an ultrasonic bone curette. A tubular retractor was introduced into the extraforaminal zone using Wiltse approach. After a part of the ossification lesion and the nerve root were exposed, an ultrasonic bone curette was applied to remove the ossification mass. After decompression, the nerve root was found to be relaxed. The surgical time was 83 min, and blood loss was 5 g. According to the Japanese Orthopedic Association scoring system, her score improved from 21/29 preoperatively to 29/29 postoperatively, and the full score was maintained at the final observation. Post-operative CT revealed the absence of an ossification lesion.

Conclusions:

For a rare case with radiculopathy resulting from intraforaminal stenosis of the lumbar spine due to an ossification lesion, microendoscopic surgery with an ultrasonic bone curette was very effective. The use of ultrasonic bone curette is easy and safe in microendoscopic surgery and it helps achieve less invasiveness and ideal decompression, without injuring the nerve root.