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ORIGINAL ARTICLE
Year : 2023 | Volume
: 14
| Issue : 1 | Page : 44-49
Surgical approach to single-level symptomatic thoracic disc herniations through costotransversectomy: A report of ten case series
Dalila Scoscina1, Silvia Amico1, Edoardo Angeletti1, Monia Martiniani2, Leonard Meco2, Nicola Specchia1, Antonio Pompilio Gigante1
1 Department of Clinical and Molecular Sciences, Politecnica delle Marche University, Ancona, Italy
2 Clinic of Adult and Paediatric Orthopaedics, University Hospital, Ospedali Riuniti of Ancona, Ancona, Italy
Correspondence Address:
Silvia Amico
Department of Clinical and Molecular Sciences, Universita Politecnica delle Marche, Via Tronto 10/a, 60020 Torrette di Ancona, Ancona
Italy
Source of Support: None, Conflict of Interest: None
CheckDOI: 10.4103/jcvjs.jcvjs_146_22
Abstract
Study Design: This was an observational study.
Objectives: The treatment of symptomatic thoracic disc herniation (TDH) remains a matter of debate. We report our experience with ten patients affected by symptomatic TDH, surgically treated through costotransversectomy.
Methods: A total of ten patients (four men and six women) with single-level symptomatic TDH were surgically treated by two senior spine surgeons at our institution between 2009 and 2021. The most common type was a soft hernia. TDHs were classified as lateral (5) or paracentral (5). Preoperative clinical symptoms were varied. The diagnosis was confirmed by computed tomography (CT) and magnetic resonance imaging of the thoracic spine. The mean follow-up period was 38 months (range: 12–67 months). The Oswestry Disability Index (ODI), the Frankel grading system, and the modified Japanese Orthopedic Association (mJOA) scoring system were used as outcome scores.
Results: Postoperative CT study documented satisfactory decompression either on the nerve root or the spinal cord. All patients experienced a reduction of disability with an improved mean ODI score by 60%. Six patients reported total recovery of neurological function (Frankel Grade E) and four patients improved by 1 Grade (40%). The overall recovery rate estimated with the mJOA score was 43.5%. We reported the absence of significant difference in outcome compared to either calcified and noncalcified discs or paramedian and lateral location. Four patients had minor complications. No revision surgery was required.
Conclusion: Costotransversectomy represents a valuable tool for spine surgeons. The major limit of this technique is the possibility to approach the anterior spinal cord.
Keywords: Costotransversectomy, single-level symptomatic thoracic disc herniation, symptomatic thoracic disc herniation, thoracic spine
Introduction 
Symptomatic thoracic disc herniation (TDH) is a rare disease,[1],[2],[3],[4] making the treatment of this entity challenging for spine surgeons. TDHs affect individuals, especially between the third and fifth decade of life.[5] Diagnosis is often unexpected or delayed in regard to vague clinical manifestations including diffuse and/or well-localized back pain, radicular pain, and progressive myelopathy.[6] However, the diagnostic accuracy of computed tomography (CT) and magnetic resonance (RM) imaging has made its detection easier. The high rates of morbidity and mortality associated with the laminectomy approach for the treatment of TDHs[7],[8] led to the development of several surgical strategies, allowing adequate visualization of the lesions, and avoiding spinal cord manipulation as possible.[9],[10],[11] In literature, there is no consensus on the treatment of choice of TDHs. A review reported better results after transthoracic techniques compared with those noted after lateral and posterolateral procedures despite transient pulmonary complications.[12] We report our experience with ten patients affected by symptomatic TDH, surgically treated through costotransversectomy.
Methods A total of ten patients with single-level symptomatic TDH were surgically treated at our institution between 2009 and 2021. This is an observational study, so local ethics committees confirmed that no ethical approval was required. All patients were identified from our electronic operative records database and included in this study in line with the principles of the Declaration of Helsinki. There were four men and six women, and the average patient age was 42 years (range: 30–47). Costotransversectomy was performed by two senior spine surgeons. One-half of the patients suffered from lateral disc herniations, while the other half had paramedian disc herniations. Fifty percentage of the lesions were located at the T8-T9 level and the most common type was a soft hernia. General data of cases are reported in [Table 1] and [Figure 1]. The percentage of presenting clinical symptoms was varied: local pain (70%), radicular pain (70%), tingling and numbness in lower extremities (100%), sensory deficits (80%), lower limbs weakness (60%), spastic paraparesis (50%), and sphincter dysfunction (50%). Decreased ability to walk affected all patients in our series. The diagnosis was confirmed by CT and magnetic resonance imaging of the thoracic spine. Follow-up was conducted at 1, 3, 6, and 12 months postoperatively and consisting of serial clinical and neurological evaluations and X-ray or CT.
Table 1: Thoracic disc herniation features in 10 patients undergoing discectomy through costotransversectomy
Figure 1: Axial view of CT image showing soft thoracic disc herniation; (a) axial view of CT image showing calcified thoracic disc herniation; (b) sagittal view of CT image showing mixed-type thoracic disc herniation (c). CT: Computed tomographyOutcome scores
Each patient's back and radicular pain was assessed by the Oswestry Disability Index (ODI) while their neurological function was documented using the Frankel grading system and the modified Japanese Orthopedic Association (mJOA) scoring system.[13] All scores were recorded pre-operatively and at each follow-up visit. Percentage of neurological recovery for each patient was estimated on the basis of the recovery rate (RR) using the following formula:
RR = (Postoperative mJOA − Preoperative mJOA)/(18 − Preoperative mJOA) ×100%.
Surgical technique
Costotransversectomy is a posterolateral approach to the thoracic spine. Each patient was placed prone. The use of intraoperative X-ray beams is mandatory to identify the correct spinal level of exposure. Several types of incisions can be performed; the two spine surgeons were more confident with a posterior midline skin incision and its T-shaped variant. Unilateral subperiosteal dissection was performed in a medial-to-lateral direction. The exposure was ipsilateral to the side of the symptomatic herniation and included the spinous process, the lamina, and facet joints. After blunt dissection of the erector spinae muscles on the transverse process and the rib surface, the rib head was disarticulated at the costovertebral joint [Figure 2]. Then, the rib 5 cm laterally to its head as well as the transverse process is removed with a gain of the lateral view of the vertebral body. At this step, great care is taken to avoid damage to the pleura. Bluntly subperiosteal dissection of the lateral aspect of the vertebral bodies rostral and caudal to the herniated disc was performed, thus visualizing the involved disc space. Following the intercostal neurovascular bundle medially, the respective pedicle was identified and removed, thus exposing the lateral portion of the thecal sac and its compression by disc herniation. Then, the authors created a small groove or cavity removing the posterior surface of the upper and lower vertebral bodies [Figure 3]. This manoeuver facilitates gentle removal of the lateral portion of the disc, while the last midline fragments are pushed downward into the groove by cerebrospinal fluid pressure. Discectomy was performed with an intervertebral disc Rongeur. Finally, the spinal cord and nerve root were decompressed.
Figure 3: Postoperative axial (a) and sagittal (b) view of computed tomography images demonstrating the creation of a small groove or cavity removing the posterior surface of vertebral bodiesStatistical analysis
Statistical analysis was performed using Excel (Microsoft, Redmond, WA, USA). Student's t-test was used to investigate differences in preoperative and following-up clinical outcomes scores. P < 0.05 was assumed as statistically significant.
Results No instrumented posterior fusion was requested. The mean time for surgery was 244 min (range: 201–276 min). Motor-evoked potentials and somatosensory-evoked potentials monitoring remained unchanged during the procedure. No patient required intraoperative blood transfusion thanks to the small estimated blood loss. The average hospitalization time was 6, 4 days (range: 5–8 days). In all patients, satisfactory resection of herniated disc was documented on a postoperative CT study: according to an independent neuroradiologist in only 3 patients (30%), minimal disc remnants were still in the side without compressive effect either on the nerve root or the spinal cord. All patients who experienced preoperative back or radicular pain had a successful resolution of their symptoms as reflected by postoperative ODI score [Figure 4]. However, postoperative neurological examination revealed an improvement in lower-extremity strength and sensitivity. Preoperatively, the Frankel Grade was B in one patient, C in five patients, and D in four patients. After surgery, six patients reported total recovery (Frankel Grade E) and four patients improved by 1 Grade (40%). In all cases, normal bowel and bladder function was restored. The pre-and postoperative mJOA score of this series is shown in [Figure 5]. The overall RR estimated with the mJOA score was 43. 5%. All pre-and postoperative outcome scores in this series showed statistically significant differences (P < 0.05). No patient experienced neurological worsening postoperatively. Three months after surgery, all patients regained the ability to walk unassisted with return to their jobs. The mean follow-up period was 38 months (range: 12–67 months). Four of ten patients had complications. One patient developed postoperative wound dehiscence, but this resolved secondarily. There were three cases of postoperative transient intercostal neuralgia with complete resolution at 3 months of fluorouracil (FU). No revision surgery on the thoracic spine was required. At the final FU, there was no clinical or radiological sign of instability or collapse at the discectomy site.
Figure 4: Pre-and postoperative ODI score of 10 patients affected by thoracic disc herniation treated by costotransvesectomy. ODI: Oswestry Disability Index
Figure 5: Pre-and postoperative mJOA score of 10 patients affected by thoracic disc herniation treated by costotransvesectomy. mJOA: modified Japanese Orthopedic Association Discussion Surgical TDH management is still considered a challenge. Laminectomy was employed as the only surgical option in thoracic disc disease until the 1960s when it was abandoned due to poor results.[7],[14] Consequently, a multitude of new surgical techniques was developed to minimize the risk of damage to the spinal cord and destabilization of the spinal column. The literature reported transpedicular, transfacet pedicle-sparing approaches, lateral extracavitary, and its variant, costotransversectomy, transthoracic transpleural approach, and thoracoscopic approach, each with unique advantages and disadvantages.[12] To date, there is no gold standard approach.
More recently, several studies suggested thoracoscopic microdiscectomy as a safe and effective technique for single-level TDH, with low morbidity rate.[15],[16] However, posterolateral approaches to the thoracic spine are still applied.[17] The two spine surgeons had skill and experience with costotransversectomy and our analysis reveals that this approach yields successful results in a wide range of symptomatic TDH. According to the analysis of our results of back and radicular pain control in this population, all patients experienced a reduction of disability and a return to better clinical status with an improved mean ODI score by 67%. We chose both the Frankel grading system and the mJOA score for a more accurate evaluation of neurological function and comparing pre-and postoperative results, we found a significant difference. The most satisfactory data obtained quantifying the compromise and further recovery concerns lower limb weakness, spastic paraparesis, and sphincter dysfunction that show a significant high percentage of success at a mean FU of 38 months. Another meaningful endpoint in the discussion of our results is the absence of a significant difference in outcome compared to either calcified and noncalcified discs or paramedian and lateral location (P < 0.05). The details are shown in [Table 2]. In a recent comparative cohort study,[18] the authors stated that large calcified paramedian herniated discs were best treated by mini-transthoracic approach, whereas in noncalcified or lateral herniated discs, a posterolateral transpedicular approach can be performed.
Table 2: Comparison of outcome between calcified and noncalcified discs or paramedian and lateral location revealing no significant difference (P=0.471Mulier and Debois[12] reviewed the literature reporting a series of 324 cases with TDHs undergoing anterior, posterolateral, or lateral approach and they clearly indicated the degree of preoperative symptoms and their duration as statistically significant factors predicting prognosis, while the location or level of herniated discs and the presence of calcification or intradural penetration did not correlate with neurological recovery. This was also found in our study: in fact, patients with poorer preoperative neurological status recovered later.
Kerezoudis et al.[19] reported postoperative complications associated with anterior (thoracotomy or thoracoscopy), lateral (extracavitary or costotransversectomy), or posterior (transpedicular or laminectomy) approaches to the thoracic spine in a total of 388 patients. Comparing the 30-day surgical outcomes profiles, the average hospitalization time was significantly longer for patients undergoing an anterior approach, who spent, on average, 2–3 more days in the hospital. Odds of major complications and discharge disposition were similar, although a higher proportion of patients in the anterior group developed pneumonia (6%) compared to other approaches (lateral, 1%; transpedicular, 3%; and laminectomy, 0%) and this difference was statistically significant. Several authors[12] described pulmonary complication rate of 0% in patients who performed a posterolateral approach and clearly stated that a posterolateral surgery was a reasonable alternative in the presence of preexisting pulmonary comorbidities.
In our study group, we had no major complications but only minor, transient complications in 40% of cases. Rapid pain relief, low postoperative discomfort, and short hospitalization time fulfilled the expectations of most of the patients. The need of instrumentation-aided fusion after surgical TDH excision is debated. In our experience, the bone removal produced no instability that required arthrodesis although in the literature some authors consider it appropriate to perform segmental stabilization to prevent postoperative destabilization of the thoracic spine after the decompressive surgery. Bransford et al.[20] reported 18 consecutive patients undergoing a transfacet pedicle-sparing decompression and segmental instrumentation with interbody fusion. They emphasized the addition of arthrodesis to provide a more comprehensive decompression and to protect from secondary instability ensuring the maintenance of the physiological thoracic balance. Furthermore, this procedure avoids postoperative axial back pain caused by the increased segmental mobilization, especially in the lower thoracic spine. No patient of our series underwent fusion months later and this is in line with a study published by Broc et al.,[21] in which single-level microdiscectomy did not affected significantly kinematics and load-deformation relationships in five human cadaveric thoracic spines. Nevertheless, preexisting osteoporosis, deformity, or kyphosis are recommendations for arthrodesis.[21],[22] Ultimately, we believe that costotransversectomy may be a feasible and successful procedure in patients harboring such a single-level thoracic lesion. It was also used to decompress the spinal cord after a traumatic or pathological fracture, a tumor shrinkage, to perform biopsies of the vertebral body,[23] and to drain abscesses.[24] This technique allows exposure of the entire length of the thoracic spine with reasonable procedural safety but limits the view of the anterior elements of the spinal cord with the risk of dural tears. Hence, the procedure should be considered in the treatment of lower TDH to avoid the release of the diaphragm and a retroperitoneal dissection.
The retrospective study design and small sample sizes derived from a single institution are the limits of this study.
Conclusion The treatment of TDHs remains a matter of debate. The current study attempted to provide useful insights into surgical TDH management. Costotransversectomy represents a valuable tool for spine surgeons as it allows complete or nearly complete decompression of the spinal canal with exposure of its entire length and does not create a postoperative instability that requires instrumentation. Furthermore, this approach minimizes many complications related to thoracotomy, especially pulmonary, thus being better tolerated in elderly or high-risk patients. Costotransversectomy offers an effective alternative to optimize the surgical strategy of a large proportion of patients with symptomatic TDHs, but detailed knowledge of anatomy and careful patients' selection is crucial to avoid complications. Nevertheless, certain cases require direct ventral access to the anterior spinal cord, so spine surgeons should gain sufficient skill and experience in anterior approaches to the thoracic spine to safely remove these lesions.
Acknowledgments
The authors would like to thank Health Physics Department, Ospedali Riuniti di Ancona for the support.
Financial support and sponsorship
Nil.
Conflicts of interest
The authors certify that they have NO affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers' bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or nonfinancial interest (such as personal or professional relationships, affiliations, knowledge, or beliefs) in the subject matter or materials discussed in this manuscript.
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