2025 年 12 巻 p. 147-152
Surgical treatment of thoracic disc herniation is challenging for spinal surgeons because of the kyphotic structure of the thoracic spine and the obstruction caused by the ribs and lungs during the lateral approach. In particular, highly migrating thoracic disc herniation requires the removal of surrounding structures, including the ribs, pedicles, and vertebral body. We present a case in which an upward-migrating T11/12 thoracic disc herniation was safely removed using full-endoscopic spine surgery. The patient was a 63-year-old man with sudden-onset leg pain and muscle weakness. A physical examination revealed thoracic myelopathy. Magnetic resonance imaging and computed tomography showed an upward-migrating T11/12 thoracic disc herniation without ossification or calcification. Given the severe compression of the spinal cord, a full endoscopic discectomy was performed via the posterolateral approach to relieve his myelopathy. In this study, we demonstrate surgical techniques for removing upward-migrating thoracic disc herniation using full-endoscopic spine surgery. Two important surgical techniques are emphasized: 1) Removal of the inferior and superior articular processes using a high-speed drill along the articular surface at an early stage of surgery. 2) Removal of a small caudal part of the upper vertebral body to insert forceps between the vertebral body and the posterior longitudinal ligament at a later stage of surgery. Our technique is a rapid and minimally invasive method for managing upward-migrating thoracic disc herniation without ossification.
Thoracic myelopathy (TM) can result from various degenerative diseases, such as ossification of the posterior longitudinal ligament (PLL) or ligamentum flavum, ligament hypertrophy, osteophytosis, and intervertebral disc herniation.1) Thoracic disc herniation (TDH) is a relatively rare form of intervertebral disc herniation, with reported incidences ranging from 0.1% to 3% of all cases.2) Approximately 4% of TDH cases present with acute myelopathy. These herniations are often located in the lower thoracic region (between T9/10 and T11/12), tend to be large, and are sometimes calcified.3) Simple laminectomy for the corresponding thoracic area is contraindicated due to the risk of myelopathic deterioration.4)
Although several operative approaches have been proposed, removal of surrounding structures such as the rib, pedicle, and/or vertebral body is often required.4,5) The recent application of full-endoscopic spine surgery (FESS) offers new treatment options for TDH.6-15)
Uniportal FESS was initially developed for the treatment of lumbar disc herniation and has recently been applied to other pathologies, including cervical radiculopathy, spinal canal stenosis, and degenerative disc disease.16-18) The advantages of FESS include a small skin incision, minimal invasiveness (less destruction of surrounding tissues), and rapid recovery.
Considering these advantages, we successfully treated upward-migrating T11/12 TDH with myelopathy and demonstrated the operative approach in this case report.
A 63-year-old man with a 1-month history of right leg pain, muscle weakness in the right leg, and bilateral numbness on the dorsum and sole of the foot was referred to our hospital. These symptoms began after playing golf. Neurological examination revealed weakness of the right quadriceps femoris (Manual Muscle Test: MMT 4/5) and iliopsoas muscles (MMT 4/5), without bladder or bowel disturbances. The deep tendon reflexes (patella and ankle) were slightly increased on both sides. Sensory disturbances, including altered vibration sensation, were noted across a broad area of both legs (especially the anterior and medial parts of the thigh). A cane was required not only for muscle weakness but also for ataxic gait due to disturbance of the dorsal column.
Magnetic resonance imaging (MRI) of the thoracic spine revealed an extramedullary mass extending continuously from the T11/12 intervertebral disc. The mass appeared isointense on T1- and low-intensity on T2-weighted images (WIs) (Fig. 1A and B). It protruded cranially along the dorsal surface of the T11 vertebral body. A computed tomography (CT) scan revealed no ossification or calcification of the mass (Fig. 1C and D).
Preoperative T2-weighted magnetic resonance images and CT.
The red line on sagittal MRI (A) indicates the scanning plane for the axial MRI (B). Sagittal CT (C) is performed at the right vertebral foramen and axial CT (D) is performed at the T11/12 vertebral disc level.
CT: computed tomography; MRI: magnetic resonance imaging; T: thoracic
Based on the clinical course (acute onset after exercise) and radiological findings, we diagnosed the mass as an upward-migrating T11/12 TDH. We performed a full-endoscopic discectomy (FED) for this TDH using a 4.1 mm working channel endoscope via a posterolateral approach. An 8 mm skin incision was made 7 cm lateral to the midline. The endoscope was inserted onto the lateral surface of the T11/12 facet joint. After exposing the bone surface using a bipolar coagulator (Fig. 2A), both the inferior articular process (IAP) and superior articular process (SAP) were removed using a high-speed drill with a 3.5 mm diameter diamond burr (Fig. 2B and C). After sufficient exposure of the epidural fat tissue and intravertebral disc (Fig. 2D), the protruding disc material was removed using several types of forceps. To remove the upward-migrating disc material, we excised a small caudal part of the T11 vertebral body using a high-speed drill (Fig. 2E, arrowheads). This enabled the insertion of forceps between the T11 vertebral body and the PLL, resulting in the complete removal of the nucleus pulposus (Fig. 2F, Supplementary Video 1). The operation was completed in 74 mins with minimal intraoperative bleeding (10 mL, which is the measurement limit in our operating room) and without postoperative drainage. The patient started walking 3 hours post-procedure.
Chronological intraoperative findings.
After exposing the bone surface using a bipolar coagulator (A), the IAP and SAP are removed using a high-speed drill (B, C). After sufficient exposure of the EDF and IVD, the protruded disc material is removed using several types of forceps. To remove the upward migrating disc material, the small caudal part of the T11 vertebral body (T11) is removed (E, arrowheads). Finally, the nucleus pulposus is removed between T11 and the PLL (F).
EDF: epidural fat; IAP: inferior articular process; IVD: intravertebral disc; PLL: posterior longitudinal ligament; SAP: superior articular process; T: thoracic
His leg pain disappeared immediately after the FED. The patient was discharged the day after the operation. Two weeks later, he visited our outpatient clinic without a cane. Postoperative MRI demonstrated the complete disappearance of the high-intensity mass on T2-WI (Fig. 3A), with cerebrospinal fluid visible in front of the spinal cord (Fig. 3B). Furthermore, CT revealed enlargement of the right T11/12 vertebral foramen (Fig. 3D) and approximately 50% preservation of the corresponding facet joint (Fig. 3E).
Postoperative T2-weighted magnetic resonance images and CT, and Pre- and postoperative 3D-CT.
The red line on sagittal MRI (A) indicates the scanning plane for the axial MRI (B). Sagittal CT (D) is performed at the right vertebral foramen and axial CT (E) is performed at the T11/12 vertebral disc level. Preoperative (C) and postoperative (F) 3D-CT also indicate the extent of bone removal. The arrows and arrowheads indicate the removed area of the T11 vertebral body.
3D: three-dimensional; CT: computed tomography; MRI: magnetic resonance imaging; T: thoracic
TDH is challenging for spinal surgeons. Although several different approaches have been proposed to date, removal of a large area of the facet joint, rib, pedicle, and/or vertebral body is required, even when using a microscope.4) Increasing evidence supports the safety and efficacy of posterolateral approaches, even for central calcified and giant calcified TDH.5) Large exposure of surrounding tissues causes instability and subsequently requires fusion surgery.12,19) In a meta-analysis by Sofoluke et al.,12) 37% of patients treated with open surgeries underwent instrumentation. The evidence highlights the need for a minimally invasive approach to TDH.
FESS is an established strategy for the treatment of cervical and lumbar disc herniations.17,20) Although several studies on FESS for TDH are available, the approach differs slightly depending on the vertebral level. Komp and Ruetten summarized their experiences with 49 TDH cases and proposed that the extraforaminal approach (identical to the posterolateral approach) is suitable for TDH in the lower thoracic spine but not in the higher thoracic spine.6) Silva et al.8) performed a meta-analysis of TDH cases treated by FESS, including 13 studies with 285 patients, demonstrating favorable safety and efficacy outcomes. In this study, the transforaminal approach (identical to the posterolateral approach) was employed in 88.1% of cases. As TDH frequently occurs in the lower thoracic spine, we will focus on managing it using the posterolateral approach.
Several illustrated cases of TDH in the lower thoracic spine treated via the posterolateral approach have demonstrated that this technique is both safe and effective, even for calcified TDH.7,10,11,14,21-23) Telfeian and Wagner10) confirmed that appropriate enlargement of the corresponding vertebral foramen is a crucial step in this procedure, as demonstrated in their video. We completely agree with this opinion and would like to incorporate the following information: 1) not only SAP but also sufficient IAP removal is essential, and 2) the endpoint is adequate exposure of epidural fat (exposure of dural sac is not necessary) and the intravertebral disc space to manipulate forceps. For the central type of TDH, exposure of the PLL is another anatomical landmark and an alternative to the anteroposterior view of the fluoroscope. During discectomy, the lateral part of the dural sac was observed on the back of the epidural fat (Supplementary Video 1), indicating successful decompression.
Among previous TDH reports, we could not identify any information regarding upward-migrating TDH. In this case, we completely removed the upward-migrating TDH via the posterolateral approach (Supplementary Video 1). The key surgical step involved removing the dorsal protrusion of the corresponding vertebral body. The extent of removal was extremely small compared to that observed in previous surgical approaches (Fig. 3C and F).24) If fine or curved forceps were used, the extent of the procedure might have been even smaller than reported in the present study.
A comparative study is necessary to prove the significance of FESS in conventional operative strategies. Two comparative studies are present in the literature. Bae et al.13) retrospectively compared the operative outcomes of 39 FED and 38 microscopic discectomy cases. The operative time (70.6 mins vs. 175.7 mins), estimated blood loss (3.8 mL vs. 357.4 mL), and length of hospital stay (7.0 days vs. 13.0 days) were significantly better in the FED group (p < 0.05).13) Most recently, Sofoluke et al.12) conducted a retrospective comparison of operative outcomes in 41 cases of FED with those from a meta-analysis of 3,190 cases from 108 studies of open surgeries. In addition to estimated blood loss and length of hospital stay, the complication rate was statistically lower in the FED group. Our case also demonstrated similar clinical results: FED has great potential to reduce invasiveness (blood loss, damage to surrounding tissues, and requirement of instrumentation), complication rates, and hospital stay.
Here, we report a case of TM caused by an upward-migrating TDH that was treated with FESS. In addition to the removal of the IAP and SAP along the articular surface, the removal of the small caudal part of the upper vertebral body is a critical surgical step in FED for upward-migrated TDH.
We thank all the operating room staff for their technical assistance and the medical records clerks who helped collect patient data. We also thank the radiological department staff for recording the computed tomography and magnetic resonance imaging data.
The patients have provided consent for the submission of this case report to the journal.
All authors have no conflict of interest.
