Surgery for Giant Calcified Herniated Thoracic Discs: A Systematic Review

Transdural Ventral Sling Technique for Calcified Thoracic Disk Herniations

BACKGROUND

Surgery for thoracic disc herniations remains an ongoing challenge, with numerous surgical approaches, all with their own inherent risks. Discectomy via a posterior laminectomy was historically the treatment of choice; however, it was deemed very high risk with elevated rates of neurologic injury. The posterior transdural approach is an alternative surgical option for soft and calcified thoracic disc herniations.

METHODS

A 56-year-old female with many years of numbness/tingling in her hands and difficulty with fine motor tasks presented with progressive weakness and loss of balance in her legs. Imaging revealed a prominent focal central calcified disc herniation at the T5-T6 level causing severe effacement and distortion of the spinal cord. A posterior transdural approach for direct visualization of a large calcified disc herniation was performed, removing the calcified disc without the need for extensive exposure or entry into the thoracic cavity. A ventral sling of the dura was created to allow rotation of the spinal cord while removing the disc.

RESULTS

Intraoperative ultrasound confirmed complete disc resection, restoring cerebral spinal fluid flow circumferentially without residual impingement or cerebrospinal fluid leaks. At six months postsurgery, the patient's gait imbalance had resolved, and she had full lower extremity strength (5/5). Radiographic evaluation indicated stable implants without subsidence, pullout, fracture, or alignment loss.

CONCLUSIONS

The transdural approach is less invasive in nature, minimizes surgical exposure, patient morbidity, and provides better intraoperative control of the spinal cord. This constitutes an effective alternative surgical approach to both soft and calcified central thoracic disc herniations.

Reliability of a Novel Classification System for Thoracic Disc Herniations

STUDY DESIGN

This is a cross-sectional survey.

OBJECTIVE

The aim was to assess the reliability of a proposed novel classification system for thoracic disc herniations (TDHs).

SUMMARY OF BACKGROUND DATA

TDHs are complex entities varying substantially in many factors, including size, location, and calcification. To date, no comprehensive system exists to categorize these lesions.

METHODS

Our proposed system classifies 5 types of TDHs using anatomic and clinical characteristics, with subtypes for calcification. Type 0 herniations are small (≤40% of spinal canal) TDHs without significant spinal cord or nerve root effacement; type 1 are small and paracentral; type 2 are small and central; type 3 are giant (>40% of spinal canal) and paracentral; and type 4 are giant and central. Patients with types 1 to 4 TDHs have correlative clinical and radiographic evidence of spinal cord compression. Twenty-one US spine surgeons with substantial TDH experience rated 10 illustrative cases to determine the system's reliability. Interobserver and intraobserver reliability were determined using the Fleiss kappa coefficient. Surgeons were also surveyed to obtain consensus on surgical approaches for the various TDH types.

RESULTS

High agreement was found for the classification system, with 80% (range 62% to 95%) overall agreement and high interrater and intrarater reliability (kappa 0.604 [moderate to substantial agreement] and kappa 0.630 [substantial agreement], respectively). All surgeons reported nonoperative management of type 0 TDHs. For type 1 TDHs, most respondents (71%) preferred posterior approaches. For type 2 TDHs, responses were roughly equivalent for anterolateral and posterior options. For types 3 and 4 TDHs, most respondents (72% and 68%, respectively) preferred anterolateral approaches.

CONCLUSIONS

This novel classification system can be used to reliably categorize TDHs, standardize description, and potentially guide the selection of surgical approach. Validation of this system with regard to treatment and clinical outcomes represents a line of future study.

Giant calcified thoracic disk herniations: ossification of PLL or autonomous entity?

BACKGROUND

Giant calcified thoracic disk herniation (GCTD) is an uncommon event, which requires surgical treatment in less than 1% of patients. GCDTs are a specific subgroup of herniated thoracic disks occupying more than 40% of the spinal canal showing calcifications associated with a certain degree of ossification. In this paper, we are reporting our whole experience in the surgical management of GCTDs through anterior approaches. We believe that they present characteristics that associate them to the circumscribed type of ossified posterior longitudinal ligament (OPLL) with a possible common pathophysiology consisting in the dural violation.

METHODS

Twenty-three consecutive patients with GCDTs were managed through anterior approaches during the period 1996-2019 at the Niguarda Hospital, Milan, Italy. Clinical data, radiological features, surgical reports, histological findings, and outcomes were reviewed.

RESULTS

There was no mortality, whereas permanent morbidity consisted of 1 case of worsened paraparesis due to accidental spinal cord contusion. One patient required reoperation to repair a postoperative cerebrospinal fluid (CSF) leakage. All patients underwent postoperative MRI which showed excellent decompression of cord and dural sac in all cases. Histological study of en-bloc removed GCTD showed typical calcification patterns of the PLL.

CONCLUSIONS

GCDTs may be assimilated to the so-called "circumscribed type" of OPLL. The GCDTs may show the same radiological CT and MRI pattern of OPLL. The anterior accesses now represent the standard of care for GCTDs. The use of operative microscope and intraoperative monitoring is mandatory. The risk of CSF leakage can be markedly reduced by meticulous reconstruction of the dura and the placement of spinal drainage. Adequate exposition may sometimes require one or two levels of corpectomy with consequent vertebral body reconstruction and fixation of anterior column of the spine.

Comparison of Anterior Approach and Posterior Circumspinal Decompression in the Treatment of Giant Thoracic Discs

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

The treatment of giant thoracic disc herniation (gTDH)remains challenging for surgeons worldwide because of its large volume and calcified or ossified nature and the limitations of the prior small-sample-size, single-center studies reporting comparative effectiveness. We aim to compare the anterior decompression and spinal fusion (ASF) and posterior circumspinal decompression and spinal fusion (PCDF) for patients with myelopathy due to gTDH in the largest study to date by sample size.

METHODS

Preoperative and postoperative functional status, surgical details, and complication rates were compared between the 2 groups.

RESULTS

A total of 186 patients were included: 63 (33.9%) ASF and 123(66.1%) PCDF. The PCDF group had significantly shorter operation duration (163.06 ± 53.49 min vs. 180.78 ± 52.06 min, P = 0.032) and a significant decrease in intraoperative blood loss(716.83 mL vs. 947.94 mL, P = 0.045), and also a shorter hospital length of stay (LOS) and postoperative LOS (6 vs. 7, P = 0.011). The perioperative complication rate (13.8% vs. 28.6%, P = 0.015) and surgery-associated complication rate(13.0% vs. 27.0%, P = 0.018) were significantly higher in the ASF group. A higher rate of complete decompression was achieved in the PCDF group. There were no observed significant differences in changes in functional status between the 2 groups.

CONCLUSION

PCDF for central or paracentral gTDHs is a highly effective and reliable technique. It can be performed safely with a low complication rate. If either procedure can adequately excise a central or paracentral gTDH, a PCDF approach may be a better option.

Minimally invasive dorsal approach in the surgery of giant thoracic disc herniation: technical note and clinical case report

Giant thoracic disc herniations are calcified hernias that fill more than 40% of the spinal canal and result in myelopathy with associated neurological symptoms. This is a fairly rare abnormality that requires surgical treatment. Currently, there is no unambiguous opinion about the surgical approach to the treatment this pathology. It is believed that the most effective method is the anterior approach (mini-thoracotomy or thoracoscopic approach), which reduces the risks of spinal cord injury, but is associated with the risks of damage to the lungs, pleura and major vessels. It is also quite large. We describe the case of a 60-year-old female patient with a giant thoracic disc herniation. Complete removal of the hernia through a minimally invasive dorsal approach was performed, followed by stabilization. No complications have been registered after the surgery. In this case, surgery resulted in a curative treatment outcome for the patient.

"White cord syndrome after cervical or thoracic spinal cord decompression. Haemodynamic complication or mechanical damage? An understimated nosographic entity"

The ischemia-reperfusion mechanism is believed to be responsible for parenchymal damage caused by temporary hypoperfusion and worsened by the subsequent attempt of reperfusion. This represents a true challenge for physicians of several fields, including neurosurgeons. A limited number of papers have shed the light on a rare pathological condition that affects patients experiencing an unexplained neurological deficit after spine surgery, the so-called "white cord syndrome". This entity is believed to be caused by an "ischemia-reperfusion" injury on the spinal cord, documented by a post-operative intramedullary hyperintensity on T2 weighted MRI sequences. To date, the cases of white cord syndrome reported in literature mostly refer to cervical spine surgery. However, the analysis of several reviews focusing on spine surgery outcome suggest that post-operative neurological deficits of new onset could be charged to a mechanism of ischemia-reperfusion, even if the physiopathology of this event is seldom explored or at least discussed. The same neuroradiological finding can suggest a mechanical damage due to surgical inappropriate manipulation. On this purpose, we performed a systematic revision of literature with the aim to identify and analyze all the factors potentially contributing to ischemic-reperfusion damage of the spinal cord that may potentially complicate any spinal surgery, without distinction between cervical or thoracic segment. Finally, we believe that post-operative neurological deficit after spinal surgery constituting the "white cord syndrome", could be underreported, while both neurosurgeons and patients should be fully aware of this rare but potentially devasting complication burdening cervical and thoracic spine surgery.

Herniated discs: when is surgery necessary?

In all levels of disc herniations the absolute surgical indications include deteriorating neurological deficits with myelopathy or cauda equina syndrome. However, this review summarized the relative indications for surgery in each level.

In cervical disc herniation (CDH), the indications for surgery consist of six months of persisting symptoms, not responding to conservative treatment. However, high-quality studies are lacking, and a randomized controlled trial is now underway to clarify the indications.

In thoracic disc herniation (TDH), the indications for surgery comprise failure of conservative measures and/or worsening neurological symptoms. Moreover, giant calcified thoracic disc herniations or myelopathy signs on magnetic resonance imaging, even in the absence of neurological symptoms, may benefit from surgical treatment as a preventive measure.

In lumbar disc herniation (LDH), the indications for surgery include imaging confirmation of LDH, consistent with clinical findings, and failure to improve after six weeks of conservative care.

Cite this article: EFORT Open Rev 2021;6:526-530. DOI: 10.1302/2058-5241.6.210020

Posterior transdural resection of giant calcified thoracic disc herniation in a case series of 12 patients

Calcified thoracic disc herniations present a rare and challenging entity. Due to the close proximity to the spinal cord and relative narrowing of the spinal canal, the optimal approach remains a matter of debate. While the transthoracic approach is usually preferred, we adapted a new technique described in 2012: the transdural posterior approach. Our aim was to evaluate its benefits in patients with giant thoracic disc protrusions. We retrospectively reviewed all patients treated in our neurosurgical department from July 2012 to March 2020. Demographics, pre- and postoperative clinical status, and operative technique and complications were extracted and analyzed. In total, 12 patients underwent a posterior transdural resection of giant calcified thoracic hard discs between 2012 and 2020. All patients underwent a posterior decompression (laminectomy, hemilaminectomy, or laminoplasty). The median duration of surgery was 152 min. Transient postoperative neurological deterioration occurred in 4 patients, with complete recovery until time of discharge. No patient underwent a surgical revision. The transdural resection of giant calcified thoracic hard discs through a posterior approach provides an excellent decompression with sufficient visualization of the spinal cord and a satisfying postoperative outcome.

Transforaminal Endoscopic Thoracic Discectomy: Technical Review to Prevent Complications

For all the spine surgeons, thoracic disc herniations (TDHs) entrust a real challenge in terms of patient diagnosis, proper selection, surgical technique, and potential adverse events. TDHs are relatively uncommon compared to the lumbar and cervical levels. Literature reports a variable prevalence of TDHs around 6% to 40%, but less than 1% of all disk herniations are symptomatic TDHs, evidencing as a relatively unusual condition. Nowadays, transforaminal endoscopic thoracic discectomy (TETD) has been implemented as an alternative to classic open procedures with results that are as good as and, in some situations, better than those in traditional discectomy. However, the surgeon must be familiar with endoscopic lumbar spine surgery before opting to perform a TETD, considering that the learning curve is much harder. We describe all the steps and safety considerations during TETD based on the anatomic differences compared to lumbar endoscopic procedures. TETD is an effective and safe method that yields more benefits, provides a direct route to the lesion with less morbidity, and is performed in a minimally invasive way. Many severe complications related to the thoracic region could be avoided having the proper knowledge, adequate technique, and safety routes and considerations.

Complications Associated with Surgery for Thoracic Disc Herniation: A Systematic Review and Network Meta-Analysis

BACKGROUND

A systematic review and network meta-analysis (Prospero ID CRD42018106936) were performed.

OBJECTIVE

The selection of the appropriate surgical approach for the management of thoracic disc herniation (TDH) is often challenging because of the frequency and variability of the associated complications. We evaluated the safety of the surgical approaches for TDH by estimating the mortality (Q1) and morbidity (Q2), and frequency of the most common complications (Q3).

METHODS

We searched the medical literature for randomized controlled trials and observational studies reporting on the management of TDH. Postoperative complications were the outcome of interest. The absolute and relative risk estimates, along with the rank probability scores, were estimated for each approach, through a network meta-analysis. The results were read in the light of the quality of the available evidence.

RESULTS

Fifteen studies with a total of 1036 patients fulfilled our eligibility criteria. Three deaths were reported. The overall morbidity was as high as 29%, largely attributed to medical (21%; 95% confidence interval [CI], 10%-38%), surgical site (11%; 95% CI, 5%-22%), cerebrospinal fluid-related (8%; 95% CI, 3%-8%), and neurologic complications (5%; 95% CI, 1%-24%). The anterior and lateral approaches were associated with a higher risk for medical and surgical complications compared with the posterolateral approach.

CONCLUSIONS

Surgery for TDH is associated with minimal mortality but significant morbidity, with large variations among the available approaches. An understanding of the perioperative complications rates is important to develop complication avoidance strategies and to aid accurate patient-to-doctor communication.

A Review of Minimally Invasive Surgical Techniques for the Management of Thoracic Disc Herniations

Thoracic disc herniation (TDH) is a rare, but technically challenging, disorder. Apart from their unfamiliarity with this condition, surgeons are often posed with challenges regarding the diverse methods available to address TDH, the neurological disturbances accompanying the disorder, the prospect of iatrogenic cord damage during surgical procedures, and the complications associated with various surgical approaches. In today's era, when minimally invasive surgery has been incorporated into almost every aspect of managing spine disorders, it is necessary for surgeons to be aware of the various minimally invasive techniques available for the management of these rare and difficult conditions. In this review article, we provide a synopsis of the epidemiology, clinical features, and technical aspects of TDH, starting from level identification to intraoperative neuromonitoring and including important steps and guidance for all the minimally invasive approaches to TDH. We conclude the review by providing insights into the clinical decision-making process and outline the specific aspects of "giant" thoracic discs and indications for fusion in certain conditions. Outcomes of minimally invasive surgery for these conditions are generally favorable. The location of herniation is an important factor for surgical planning.

Giant Thoracic Calcified Disk: Conservative Management with 3-Year Follow-Up

Calcified disk herniation of the thoracic spine is by no means a rare clinical entity in neurosurgery. We present a 63-year-old woman with a long-standing giant calcified disk in the thoracic spine. Initial imaging studies indicated a differential diagnosis of calcified disk versus meningioma. Given her benign neurologic examination and the presumed morbidity of attempting to resect the lesion, we elected to follow her closely with serial imaging. Over 3 years of consistent follow-up, the lesion has not grown and she has remained free of neurologic changes.

Surgical treatment of thoracic disc herniation: an overview

BACKGROUND

Surgical treatment of thoracic disc herniation (TDH) is technically demanding due to its proximity to the spinal cord.

METHODS

Literature review.

RESULTS

Symptomatic TDH is a rare condition predominantly localized between T8 and L1. Surgical indications include intractable back or radicular pain, neurological deficits, and myelopathy signs. Giant calcified TDH (> 40% spinal canal occupation) are frequently associated with myelopathy, intradural extension, and post-operative complications. Careful pre-operative planning helps reduce the risk of complications. Pre-operative CT and MRI identify the hernia's location and size, calcifications, and intradural extension. The approach must provide adequate dural sac visualization with minimal manipulation of the cord. Non-anterior approaches are favoured if they provide at least equal exposure than anterior approach owing to higher risk of pulmonary morbidity associated with anterior approach. A transthoracic approach is recommended for central calcified herniated discs. A posterolateral approach is often suitable for non-calcified lateralized TDH. Thoracoscopic approaches are less invasive but have a substantial learning curve. Retropleural mini-thoracotomy is an acceptable alternative. Pre-operative identification of the pathological level is confirmed by intra-operative level check. Intra-operative cord monitoring is preferable but warrant further studies. Magnification and adequate lightening of the surgical field are paramount (microscope, thoracoscopy). Intra-operative CT scan with navigation is becoming increasingly popular since it provides real-time control on the decompression. Indications of fusion consist of pre-operative back pain, Scheuermann's disease, multilevel resection, wide vertebral body resection (> 50%), and herniation at thoracolumbar junction. Neurological deterioration, dural tear, and subarachnoid-pleural fistula are the most severe complications.

CONCLUSION

Further improvements are still warranted in thoracic spine surgery despite the advent of minimally invasive techniques. Intra-operative CT scan will probably enhance the safety of the TDH surgery.