Skin markers for surgical planning for intradural lesions of the thoracic spine. Technical note

Oblique radiograph with methylene blue marking: A reliable technique for upper thoracic level localization

Purpose

Traditionally, plain radiographs are used in intraoperative spinal level localization (SLL), whereas counting vertebrae is often hampered by shoulders and scapulae in lateral views, thus increasing the potential for wrong-level surgery. To improve the localization accuracy, this study evaluated the safety and feasibility of oblique radiographs with methylene blue markings for SLL and explored the optimal angle and height of oblique radiographs.

Methods

The clinical data of 33 patients with upper thoracic spine lesions who were operated on in our hospital from January 2021 to April 2022 were retrospectively analyzed. Oblique radiographs with methylene blue markings were used for intraoperative SLL.

Results

A total of 33 patients were included in this study. The average BMI was 24.3 ± 0.7 kg/m². The ipsilateral lamina structures were clearly shown in all cases. The median radiographing times of all the patients was 3, and the median radiographing duration was 2 min and 25 s. The average angle of oblique radiographs was 55.1 ± 3.8°, and the average distance from the skin to the root of the spinous process was 4.9 ± 1.2 cm.

Conclusions

Using oblique radiographs with methylene blue markings, not only the bone structure of an upper thoracic spine can be revealed clearly, but also the positioning deviation of traditional needle localization can be avoided. The lesion segment can be precisely located by this technology during surgery. Our angle of oblique radiographs and height determination method can be used to reduce the radiation exposure and shorten the operation time.

A modified vertebroplasty technique for intraoperative thoracic spine localisation: a technical report

The aim is to illustrate the modified vertebroplasty technique as a fixed marker for intraoperative thoracic spine localisation. Open and minimally invasive surgery in the thoracic spine has been correlated with a disproportionately high rate of wrong-level spinal surgery in pathologies where a focal deformity or fracture is absent. Spinal markers have evolved with time, and vertebroplasty as a spinal marker was initially described in 2008. A significant disadvantage is that the cement in the vertebral body and pedicle may preclude a more extensive osteotomy or subsequent instrumentation at the level of interest. We demonstrate the modified vertebroplasty technique, which introduces percutaneous polymethylmethacrylate cement two levels below the thoracic disc herniation on the contralateral side to the surgical approach using standard vertebroplasty methods. The vertebroplasty was performed as an outpatient procedure, and the radiopaque cement was instantaneously located on intraoperative fluoroscopy, identifying the correct level above. The modified vertebroplasty technique is a quick, safe and accurate method of thoracic spine localisation, facilitating the room required for the bony exposure and instrumentation if needed.

Novel 2D long film imaging utility to avoid wrong level spinal surgery

Wrong-level spinal surgery (WLSS) can lead to increased morbidity, cost, and worse long-term outcomes. Current intraoperative localization methods rely on counting spinal levels from a known reference location using fluoroscopy. Miscounting from a reference is an intraoperative error that leads to WLSS, especially for those with anatomical variations. The problem is exacerbated when fluoroscopy is not able to produce images with the clarity needed to confidently count levels, a prevalent issue for obese patients.

A new feature called the “2D Long Film'' is available for the Medtronic (Minneapolis, MN) O-arm Surgical Imaging System. Using this novel technology and standard fluoroscopy, this study reports the imaging of two obese adult female patients with a body mass index of 36.9 and 42.0 undergoing transforaminal thoracic interbody fusion. Fluoroscopy images of obese patients are difficult to capture for two reasons: increased scatter and restricted field of view. This report demonstrates that 2D Long Film can improve both these issues for obese patients in need of thoracic localization. The 2D Long Film captures existing instrumentation, localization needles, and the vertebral levels in a clear single image.

We display the differences between standard fluoroscopy and the 2D Long Film for thoracic level localization, demonstrating a potential new standard of care and better visualization, leading to a less challenging vertebrae localization process, potentially mitigating WLSS risk. The quality of this new 2D Long Film feature could also reduce time in the operating room and the necessity of other visualization methods.

Pre- and intraoperative thoracic spine localization techniques: a systematic review

OBJECTIVE

In the era of modern medicine with an armamentarium full of state-of-the art technologies at our disposal, the incidence of wrong-level spinal surgery remains problematic. In particular, the thoracic spine presents a challenge for accurate localization due partly to body habitus, anatomical variations, and radiographic artifact from the ribs and scapula. The present review aims to assess and describe thoracic spine localization techniques.

METHODS

The authors performed a literature search using the PubMed database from 1990 to 2020, compliant with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). A total of 27 articles were included in this qualitative review.

RESULTS

A number of pre- and intraoperative strategies have been devised and employed to facilitate correct-level localization. Some of the more well-described approaches include fiducial metallic markers (screw or gold), metallic coils, polymethylmethacrylate, methylene blue, marking wire, use of intraoperative neuronavigation, intraoperative localization techniques (including using a needle, temperature probe, fluoroscopy, MRI, and ultrasonography), and skin marking.

CONCLUSIONS

While a number of techniques exist to accurately localize lesions in the thoracic spine, each has its advantages and disadvantages. Ultimately, the localization technique deployed by the spine surgeon will be patient-specific but often based on surgeon preference.

[Spinal motor segment labeling with a mixture of n-butyl-2-cyanoacrylate and iohexol in determining the level of thoracic spine surgery]

Erroneous determining the level of spine surgery is an urgent problem in modern vertebrology. Incidence of this complication is up to 1 per 3110 patients, among patients undergoing thoracic spine surgery - 1 per 25 patients. Despite widespread use of spine surgery, there is still no standard rational method for prevention of erroneous determining the level of intervention.

OBJECTIVE

To develop a safe minimally invasive low-traumatic and cost-effective method for preoperative marking the level of thoracic spine surgery.

MATERIAL AND METHODS

A mixture of biodegradable adhesive based on cyanoacrylate and water-soluble iodine-containing X-ray contrast agent was used for preoperative marking in 8 patients scheduled for thoracic spine and spinal cord surgery. This mixture was injected into paravertebral tissues at the level of further intervention.

RESULTS

Preoperative marking ensured a fixed and clearly visible landmark during intraoperative fluoroscopy in 7 patients. In 1 patient, mixture spread in paravertebral soft tissues that did not allow us to obtain appropriate landmark during intraoperative radiography.

CONCLUSION

The described method makes it possible to create an immobile X-ray-positive «mark» in paravertebral soft tissues, which can be used to control the level of intervention at all surgical stages.

Ct guided reference markers for spinal dorsal lesions: A safe and valuable tool impacting intraoperative localization time

BACKGROUND

Intraoperative localization of the correct spine level can be challenging when dealing with the thoracic spine; especially in morbidly obese patients and in mid-thoracic spine lesions. Different radiological reference markers techniques for dorsal surgery have been reported without a clear DAP (effective dose), localization and surgical time analysis.

PURPOSE

The aim of the study is to analyze the radiological reference markers technique in terms of localization time and radiation dose during surgery for dorsal lesions.

METHODS

We used a radiopaque marker (fiducial) directly positioned before surgery over the lamina or the spinous process using CT scan for precise localization and vertebra count. We prospectively collected data about patients who underwent preoperative thoracic localization between April 2015 and September 2018 at Neurosurgery Department of Ferrara University Hospital. Clinical data as pathology, related surgical technique, radiological exams, localization time and radiation exposure were analyzed.

RESULTS

19 patients who underwent preoperative radiopaque marker (fiducial) positioning and 11 patients who underwent fluoroscopy technique were enrolled. No complications related to fiducial placement and no wrong-level occurred. The localization time with the fiducial was reduced dramatically (3 min vs 15 min of the standard technique). The average DAP (effective dose) for the fiducial group was 20 Gy-cm² compared with 16 Gy-cm² of the traditional group.

CONCLUSION

The use of preoperative fiducial for intraoperative localization of the target level in the thoracic spine dramatically reduce the location time without a significantly higher DAP (effective dose).

Prevention of Wrong-level Surgery in the Thoracic Spine: Preoperative Computer Tomography Fluoroscopy-guided Percutaneous Gold Fiducial Marker Placement in 57 Patients

STUDY DESIGN

Retrospective review.

OBJECTIVE

The aim of this study was to evaluate the feasibility, safety,s and complications of computer tomography (CT) fluoroscopy-guided percutaneous transpedicular gold fiducial marker insertion to reduce incidence of wrong-level surgery in the thoracic spine.

SUMMARY OF BACKGROUND DATA

Intraoperative localization of the correct thoracic level can be challenging and time-consuming, especially in obese patients and patients with anatomical variations. In the literature there are very few studies containing low numbers of patients which assessed CT or CT fluoroscopy-guided fiducial marker placement of the thoracic spine. Description of this technique has been similarly scarce.

METHODS

All patients who underwent percutaneous CT fluoroscopy-guided gold fiducial marker placement of the thoracic spine were retrospectively reviewed. Indications for surgery included degenerative disc disease, infection, spinal metastasis, and intra- and extradural tumors. Gold fiducial markers were placed using a percutaneous CT fluoroscopy-guided transpedicular approach with local anesthesia. In addition, sex, age, body mass index (BMI), thoracic level, related pathology, and procedure-related complications were also recorded.

RESULTS

A total of 57 patients (24 females, 33 males) were included. Mean age was 58.6 ± 15.5 years. No complications during CT fluoroscopy-guided gold fiducial marker placement were recorded. Intraoperative localization was successful in all patients. Mean BMI was 32.98 kg/m (range, 18.63-56.03 kg/m), and 63% of patients were obese (>30 kg/m). T7 (n = 11) was the most often marked vertebral body, followed by T10 (n = 10) and T6 (n = 7). The most cranial and most caudal levels marked were T2 and T12, respectively.

CONCLUSION

Preoperative CT fluoroscopy-guided percutaneous gold fiducial marker placement is safe, feasible, and accurate. The resulting facilitated localization of the intended thoracic level of surgery can reduce the length of surgery and prevent wrong-level surgery. Further studies are needed to evaluate in the effect on exposure to radiation and quantify the difference in operating room time.

LEVEL OF EVIDENCE

4.

A safe, reliable, inexpensive and novel technique to localize in the mid thoracic spine in the prone position: Proof of concept and technical illustration

Intraoperative localization within the thoracic spine in the prone position may be particularly difficult on account of absence of common landmarks such as the sacrum or the C2 vertebra, thus increasing the potential for wrong-level surgery that may lead to patient morbidity and potential litigation. Some current localization methods involve implantation of markers that are invasive and serve to add to procedural expense while yet still failing to entirely eliminate errors. We describe a novel, non-invasive, and inexpensive technique for intraoperative localization of the thoracic spine in the prone position using an esophageal temperature probe. Following patient positioning, anteroposterior fluoroscopy is used to localize the radiopaque tip of the esophageal probe relative to the thoracic spine. After determining the probe tip's location, it becomes the counting reference for all subsequent intraoperative fluoroscopic localizations during surgery. As the probe tip is generally visible in the same fluoroscopic image as the surgical level, error from parallax created when moving the fluoroscopy machine from an anatomic landmark either above or below is avoided and a shorter fluoroscopy time is needed. Use of an esophageal temperature probe as a landmark in localizing spinal level may serve as a reliable and It offers a safe, reliable, and inexpensive technique for proper localization of thoracic spine levels.

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.

Development of a Surface Marker for Fractional Anisotropy Maps Using Wood in a Phantom Study

Purpose:

To improve imaging, a reliable setup method is critical for the accurate localization of lesions and surface markers. Because an anisotropic marker has not yet been validated for MRI, direct localization of surface markers is not yet feasible in fractional anisotropy (FA) maps. This study aimed to develop an anisotropic surface marker using wood for an FA map and to determine whether a wood marker is useful for various sequences.

Methods:

Wood infiltrated with water was used to develop an anisotropic surface marker. The wood marker was compared with phantoms composed of clinically available markers, including MR-SPOTS Packets (Beekley Medical, Bristol, CT, USA), Breath Care Oral Refreshing Capsules (Kobayashi Pharmaceutical Co., Ltd., Osaka, Japan), and baby oil (Johnson & Johnson, New Brunswick, NJ, USA). Magnetic resonance images were acquired using the Achieva 3T TX MRI System (Philips HealthCare, Best, Netherlands) equipped with a QD head coil including T₁- and T₂-weighted imaging, proton-density-weighted imaging, T2* -weighted imaging, T₁-weighted imaging spectral pre-saturation with inversion recovery, T₂-weighted imaging spectral attenuated inversion recovery, proton-density-weighted imaging spectral attenuated inversion recovery, diffusion weighted imaging, and diffusion tensor imaging. Apparent diffusion coefficient, FA values, and signal-to-noise ratio (SNR) were measured and recorded, and the coefficient of variation was calculated for two consecutive imaging scans. The wood was observed using a microscope.

Results:

Breath Care Oral Refreshing Capsules and baby oil were not observed in the FA map. The FA value of the MR-SPOTS Packets was 0.18. The FA value of the wood marker was 0.80. The coefficient of variation of the MR-SPOTS Packets and the wood marker were 0.0263 and 0.0013, respectively, in the FA map. Microscopic observation revealed a wood anisotropic structure.

Conclusion:

The wood maker enabled direct localization in the FA map. Hence, wood markers may be useful to radiologists and contribute to obtaining useful findings.

Thoracic disc herniation: Surgical treatment

Thoracic disc herniation is rare and mainly occurs between T8 and L1. The herniation is calcified in 40% of cases and is labeled as giant when it occupies more than 40% of the spinal canal. A surgical procedure is indicated when the patient has severe back pain, stubborn intercostal neuralgia or neurological deficits. Selection of the surgical approach is essential. Mid-line calcified hernias are approached from a transthoracic incision, while lateralized soft hernias can be approached from a posterolateral incision. The complication rate for transthoracic approaches is higher than that of posterolateral approaches; however, the former are performed in more complex herniation cases. The thoracoscopic approach is less invasive but has a lengthy learning curve. Retropleural mini-thoracotomy is a potential compromise solution. Fusion is recommended in cases of multilevel herniation, herniation in the context of Scheuermann's disease, when more than 50% bone is resected from the vertebral body, in patients with preoperative back pain or herniation at the thoracolumbar junction. Along with complications specific to the surgical approach, the surgical risks are neurological worsening, dural breach and subarachnoid-pleural fistulas. Giant calcified herniated discs are the largest contributor to myelopathy, intradural extension and postoperative complications. Some of the technical means that can be used to prevent complications are explored, along with how to address these complications.

Skin marker placement by technologist prior to knee MRI helps identify clinically relevant pathologies

Background

Majority of musculoskeletal cross-sectional imaging requests have a non-revealing and non-specific clinical history of pain. However, the location of pain is very relevant towards arriving at a specific orthopedic diagnosis. The purpose of this research was to study the impact of skin marker placement and training of technologists prior to knee MRI in detection of clinically important findings.

Methods

Total 200 consecutive left knee MRIs were evaluated before and after technologist training with regards to marker placement at the site of clinical symptoms or palpable finding. Marker location in relation to the knee was recorded and important findings were classified as correlated important finding, non-correlated important finding, other compartment important finding in non-correlated cases, and diffuse abnormality, i.e. tri-compartmental cartilage defects in both correlated and non-correlated cases. Differences among scans before and after technologist training were analyzed.

Results

The marker placement was observed in higher proportion of patients in post-training scans (78% vs 60%, p = 0.00). The most common location of the marker was in anterior or anterolateral knee (32% and 34% cases, respectively). The marker-important finding correlation was also higher post training, but not statistically significant (53% versus 38%, p = 0.57). Important findings correlated with the marker in more than 50% of the scans in the post-training set.

Conclusion

Marker placement can aid in detection of clinically important imaging finding and technologist training aids in increased rates of marker placement and improved correlation.

Factors predictive of topographical accuracy in spine level localization

BACKGROUND

Pre-operative spine level localization by palpation of anatomical landmarks (ribs, spinous processes) in posterior approaches for surgeries from T4 to L2 is often inaccurate. This can lead to ineffective utilization of procedural time, increased radiation dose, potentially longer skin incision and wrong level surgery. Factors affecting topographical accuracy includes body mass index (BMI) of the patient, congenital or acquired deformity and knowledge of topographical anatomy.

METHODS

All patients had the presumed location of their pathology marked on the skin using anatomical landmarks prior to application of the Target Tape^® (Vancouver, BC, Canada) and verification using an anterior-posterior radiograph. Potential factors predictive of accurate pre-operative spine level localization such as age, gender, BMI, palpable deformity, pathology related interspinous distance (ISPD) and pathology related skin to spinous process distance were evaluated.

RESULTS

A prospective study was performed with 30 consecutive patients undergoing posterior spine surgery (T4 to L2). Accuracy of pathology related spine level localization using anatomical landmarks was only 40%. Pathology related ISPDs of more than 10 mm and palpable deformity was significantly correlated with successful determination of spine levels using anatomical landmarks.

CONCLUSIONS

This study showed that poor spine level localization using anatomical landmarks was associated with pathology related ISPDs of less than 10 mm. Conversely, patients with palpable spinal deformity have their levels easily localized.

Avoidance of Wrong-level Thoracic Spine Surgery Using Sterile Spinal Needles: A Technical Report

STUDY DESIGN

A technical report.

OBJECTIVE

The aim of the present study was to present an improvement on localization techniques employed for use in the thoracic spine using sterile spinal needles docked on the transverse process of each vertebra, which can be performed in both percutaneous and open spinal procedures.

SUMMARY OF BACKGROUND DATA

Wrong-level surgery may have momentous clinical and emotional implications for a patient and surgeon. It is reported that one in every 2 spine surgeons will operate on the wrong level during his or her career. Correctly localizing the specific thoracic level remains a significant challenge during spine surgery.

METHODS

Fluoroscopic anteroposterior and lateral views were obtained starting in the lower lumbar spine, and an 18-G spinal needle was placed in the transverse process of L3 counting up from the sacrum and also at T12. The fluoroscopy was then moved cephalad and counting from the spinal needle at T12, the other spinal needles were placed at the targeted operating thoracic vertebrae. Once this was done, we were able to accurately determine the thoracic levels for surgical intervention.

RESULTS

Using this technique, the markers were kept in place even after the incisions were made. This prevented us from losing our location in the thoracic spine. Correctly placed instrumentation was made evident with postoperative imaging.

CONCLUSIONS

We have described the successful use of a new technique using spinal needles docked against transverse processes to correctly and reliably identify thoracic levels before instrumentation. The technique was reproducible in both open surgeries and for a percutaneous procedure. This technique maintains the correct spinal level during an open procedure. We posit that wrong-level thoracic spine surgery may be preventable.

Intermittent Feet Dorsiflexion as a Simple Trick to Improve Cervical Fluoroscopic Visualization

BACKGROUND

Anterior cervical surgery is routinely performed using fluoroscopy. Visualizing the lower cervical levels can be challenging, particularly in obese, muscular, and broad-shouldered patients. We found that grabbing both feet of the patient at the level of the metatarsals and cranially pushing the feet, creating dorsiflexion at the ankle joints, seems to increase the number of fluoroscopically visualized cervical levels. We aimed to measure the average change in fluoroscopically visualized levels when performing this maneuver.

METHODS

In 10 consecutive patients undergoing an anterior cervical discectomy and fusion procedure, we counted the number of fluoroscopically visualized cervical levels. Visible cervical levels in lateral fluoroscopic cervical images that were taken with and without the execution of the aforementioned maneuver were counted by 2 blinded observers.

RESULTS

Performing this maneuver added on average almost 1 vertebral body height to the fluoroscopic image. The additional number of fluoroscopically visible cervical levels was significantly higher in patients <50 years old but was not affected by sex or body mass index.

CONCLUSIONS

We propose a simple, convenient, and effective technique to increase the number of visualized cervical levels on lateral cervical fluoroscopy. This maneuver may have some advantages compared with other commonly used techniques.

Accuracy and evaluation of irradiation of novel localization devices with unique three-dimensional structures in microendoscopic spine surgery

BACKGROUND

Although many reports are available on using a variety of instruments and techniques to prevent wrong-level spine surgery, the accurate localization of the correct spinal level remains problematic. At the same time, surgeons are also required to reduce radiation exposure to patients and operating room personnel. To solve these problems, we developed and used specially designed marking devices with a unique three-dimensional structure.

PURPOSE

To evaluate the accuracy of our novel devices for localization of the spinal level to prevent wrong-level surgery and reduce the amount and time of radiation exposure during surgery.

STUDY DESIGN

This was a retrospective cohort study.

METHODS

In 8240 consecutive patients who underwent microendoscopic spine surgery between 1993 and 2012, the incidence of wrong-level surgery was studied. In addition, the amount of radiation exposure and total fluoroscopy time were measured in recent 100 consecutive patients using a digital dosimeter attached to the fluoroscope.

RESULTS

Eight (0.097 %) patients had undergone wrong-level surgery. The average radiation exposure was 0.26 mGy (range 0.10-1.15 mGy), and the average total fluoroscopy time was 3.1 s (range 1-7 s).

CONCLUSIONS

Our novel localization devices and technique for their use in spine surgery are reliable and accurate for identifying the target level and contributed to reductions in preoperative localization error and radiation exposure to patients and operating room personnel.

Assessment of fiducial markers to enable the co-registration of photographs and MRI data

PURPOSE

To investigate the visualisation of novel external fiducial skin markers in photography and MRI. To co-register photographs and MR images, and additionally assess the spatial accuracy of these co-registrations with the view of future application in the investigation of forensically relevant soft tissue lesions.

METHODS AND MATERIALS

Strand-shaped fiducial markers were secured externally over hematomas on the thigh of 10 volunteers. The region of interest was photographed and examined using MRI at 3T in oblique and transversal orientations and the visibility of the markers assessed. Markers provided 'control points' in both sets of images, enabling the computation of an affine transform to register oblique MR images to photographs. The fiducial registration error was evaluated by calculating the root-mean-square error of nine corresponding evaluation points visible in both modalities.

RESULTS

Fiducial markers were clearly visualised in both photography and MRI. The co-registration of photographs and oblique MR images was achieved for all participants. The overall root-mean-square error for registrations was 1.18mm (TIRM) and 1.46mm (TSE2D with SPAIR fat-suppression).

CONCLUSIONS

The proposed approach led to the successful visualisation of non-invasive fiducial markers using photography and MRI (TIRM and TSE2D (SPAIR) sequences). This visualisation, combined with an affine transformation process provided a simple, cost-effective way to accurately co-register photographs and MR images of subcutaneous hematomas located on the thigh. Further investigation of the novel markers and the proposed co-visualisation approach holds potential to improve not only the forensic documentation of soft tissue lesions, but to also improve certain clinical applications, including the area of dermatology.

Magnetic resonance imaging localization with cod liver oil capsules for the minimally invasive approach to small intradural extramedullary tumors of the thoracolumbar spine

Object

Accurate intraoperative localization of small intradural extramedullary thoracolumbar (T-1 to L-3 level) spinal cord tumors is vital when minimally invasive techniques, such as hemilaminectomy, are used to excise these lesions. In this study, the authors describe a simple and effective method of preoperative MRI localization of small intradural extramedullary tumors using cod liver oil capsules.

Methods

Thirty-five patients with intradural tumors underwent preoperative MRI localization the evening prior to surgery. Patients were positioned prone in the MRI gantry, mimicking the intraoperative position. Nine capsules were placed in 3 rows to cover the lesion. This localization was used to guide the level for a minimally invasive approach using a hemilaminectomy to excise these tumors.

Results

The mean patient age was 51.5 ± 14.3 years, and the mean body mass index was 24.1 ± 3.5 kg/m2. Twenty-two tumors involved the thoracic spine, and 13 involved the upper lumbar spine from L-1 to L-3. The mean tumor size was 2.2 ± 1.0 cm. Localization was accurate in 34 patients (97.1%).

Conclusions

Accurate localization with the described method is quick, safe, cost-effective, and noninvasive with no exposure to radiation. It also reduces operating time by eliminating the need for intraoperative fluoroscopy.

Surgical treatment for thoracic disc herniation: an update

STUDY DESIGN

Retrospective review of the literature.

OBJECTIVE

To update recent trends in the surgical treatment for thoracic disc herniation (TDH).

SUMMARY OF BACKGROUND DATA

TDH is rare; however, it is usually accompanied by myelopathy and is indicated for surgical treatment. A variety of surgical approaches have been described to reach these anatomically challenging lesions.

METHODS

Review of the literature.

RESULTS

Recently, minimally invasive techniques for TDH have gained popularity. These include thoracoscopic and mini-open anterolateral retropleural approaches, as well as microscopic and endoscopic surgery. In addition, this article updates important aspects of surgical treatment for TDH such as definition of surgical level, treatment of calcified and/or giant disc, multilevel lesions, and fusion requirements.

CONCLUSION

Definition of surgical level is imperative in the surgical treatment for TDH. Outcomes of minimum invasive surgery are satisfactory. Type of disc herniation and biomechanical stability are the important factors for surgical planning.

Novel technique for preoperative pedicle localization in spinal surgery with challenging anatomy

Accurately localizing a spine level in the thoracic spine is often not easily achieved with the existing imaging modalities available in the operating room. The coordination of the preoperative imaging pathology with intraoperative imaging is even more difficult in patients with challenging anatomy. Using standard percutaneous techniques, the authors placed a radiopaque embolization coil into the pedicle of interest under biplanar fluoroscopy in 1 patient. Thoracic spine MRI along with scout MRI was then performed to confirm coil marker placement in relation to the actual spine pathology prior to surgical intervention. No complications were observed during placement of the radiopaque marker. Intraoperatively, the marker was immediately and easily visualized, leading to a confident identification of the correct thoracic spinal level. The preoperative placement of a radiopaque marker into the vertebral pedicle of the identified pathological level combined with postplacement MRI verification provides an advantage over previously proposed techniques in the literature.

Using the C7-T3 spinous processes as landmarks for the localization of thoracic spinal lesions: technique notes

The authors describe a method of using the C7-T3 spinous processes visualized on MRI as landmarks for localizing thoracic spinal lesions in 19 cases. This method included six steps. First, the "spinous process nearest to the lesion that was visible on the MRI image" was identified. Second, a dashed line was drawn on the image through the tip of the identified spinous process perpendicular to the skin surface. Third, two additional dashed lines parallel to the first dashed line were drawn from the upper and lower margins of the lesion. Fourth, the distances between the identified process and the two additional dashed lines were measured. Fifth, the same "spinous process nearest to the lesion" was identified by palpation and marked on the patient's skin. Sixth, the upper and lower margins of the lesion were marked on the skin according to the two distances measured in step 4. After the lesion was exposed, the deviations of the lesion margins were measured. All 19 cases of the thoracic spinal lesions were localized correctly using the C7-T3 spinous processes visualized on the MRI images as landmarks without any other evaluation methods. The deviation value for the localization of the tumor margin was 4.1 ± 1.47 mm. Using the C7-T3 spinous processes as landmarks is an accurate, simple, and economic method for lesion localization during thoracic spinal surgery.

Avoidance of wrong-level thoracic spine surgery: intraoperative localization with preoperative percutaneous fiducial screw placement

Object

The accurate intraoperative localization of the correct thoracic spine level remains a challenging problem in both open and minimally invasive spine surgery. The authors describe a technique of using preoperatively placed percutaneous fiducial screws to localize the area of interest in the thoracic spine, and they assess the safety and efficacy of the technique.

Methods

To avoid wrong-level surgery in the thoracic spine, the authors preoperatively placed a percutaneous 5-mm fiducial screw at the level of intended surgery using CT guidance. Plain radiographs and CT images with reconstructed views can then be referenced in the operating room to verify the surgical level, and the fiducial screw is easily identified on intraoperative fluoroscopy. The authors compared a group of 26 patients who underwent preoperative (often outpatient) fiducial screw placement prior to open or minimally invasive thoracic spine surgery to a historical group of 26 patients who had intraoperative localization with fluoroscopy alone.

Results

In the treatment group of 26 patients, no complications related to fiducial screw placement occurred, and there was no incidence of wrong-level surgery. In comparison, there were no wrong-level surgeries in the historical cohort of 26 patients who underwent mini-open or open thoracic spine surgery without placement of a fiducial screw. However, the authors found that the intraoperative localization fluoroscopy time was greatly reduced when a fiducial screw localization technique was employed.

Conclusions

The aforementioned technique for intraoperative localization is safe, efficient, and accurate for identifying the target level in thoracic spine exposures. The fiducial marker screw can be placed using CT guidance on an outpatient basis. There is a reduction in the amount of intraoperative fluoroscopy time needed for localization in the fiducial screw group.

Intra-operative localisation of thoracic spine level: a simple "'K'-wire in pedicle" technique

PURPOSE OF STUDY

To describe a simple and reliable method of intra-operative localisation of thoracic spine in a single surgical setting. Intra-operative localisation of thoracic spine levels can be difficult due to anatomical constraints, such as scapular shadow, patient's size and poor bone quality. This is particularly true in cases of thoracic discectomies in which the vertebral bodies appear normal. There are several methods described in recent literature to address this. Many of them require a separate procedure which was performed often the previous day. We report a technique which addresses the issue of localising thoracic level intra-operatively.

MATERIALS AND METHODS

After induction of general anaesthesia, the patient was placed prone and the pedicle of interest was identified using fluoroscopy. A K-wire was then inserted percutaneously into this pedicle under image guidance [confirmed in the antero-posterior (AP) and lateral views]. The wire was then cut close to the skin after bending it. The patient was now positioned laterally and the intended procedure performed through an anterior trans-thoracic approach. The 'K' wire was removed at the end of the procedure.

RESULTS AND CONCLUSION

We routinely used this technique in all our thoracic discectomies (four cases in 2 years). There were no intra-operative complications. This method is simple, avoids the patient undergoing two procedures and requires no more ability than placing an implant in the pedicle under fluoroscopy. Placing the 'K' wire into a fixed point like the pedicle facilitates rapid intra-operative viewing of the level of interest and is removed easily at the conclusion of surgery.

Unusual spine anatomy contributing to wrong level spine surgery: a case report and recommendations for decreasing the risk of preventable 'never events'

BACKGROUND

Wrong site surgery is one of five surgical "Never Events," which include performing surgery on the incorrect side or incorrect site, performing the wrong procedure, performing surgery on the wrong patient, unintended retention of a foreign object in a patient, and intraoperative/immediate postoperative death in an ASA Class I patient. In the spine, wrong site surgery occurs when a procedure is performed on an unintended vertebral level. Despite the efforts of national safety protocols, literature suggests that the risk for wrong level spine surgery remains problematic.

CASE PRESENTATION

A 34-year-old male was referred to us to evaluate his persistent thoracic pain following right-sided microdiscectomy at T7-8 at an outside institution. Postoperative imaging showed the continued presence of a herniated disc at T7-8 and evidence of a microdiscectomy at the level immediately above. The possibility that wrong level surgery had occurred was discussed with the patient and revision surgery was planned. During surgery, the site of the previous laminectomy was clearly visualized; however, we also experienced confusion when verifying the level of the previous surgery. We ultimately used the previous laminectomy site as a landmark for identifying and treating the correct pathologic level. Postoperative consultation with Musculoskeletal Radiology revealed the patient had two abnormalities in his spinal anatomy that made intraoperative counting of levels inaccurate, including a pair of cervical ribs at C7 and the absence of a pair of thoracic ribs.

CONCLUSION

This case highlights the importance of strict adherence to a preoperative method of vertebral labeling that focuses on the landmarks used to label a pathologic disc space, rather than simply relying on the reference to a particular level. That is, by designating the pathological level as the disc space associated with the fourth rib up from the last rib-bearing vertebrae, rather than calling it "T7-8", then the correct level can be found intraoperatively even in the case of abnormal segmentation. We recommend working closely with radiology during preoperative planning to identify unusual anatomy that may have been overlooked. We also recommend that radiology colleagues use the same system of identifying pathological levels when dictating their reports. Together, these strategies can reduce the risk of wrong level surgery and increase patient safety.

Strategies to avoid wrong-site surgery during spinal procedures

Wrong-site surgery (WSS) is a rare occurrence that can have devastating consequences for patient care. There are several factors inherent to spine surgery that increase the risk of WSS compared with other types of surgery. Not only can a surgeon potentially operate on the wrong side of the spine or the wrong level, but there are unique issues related to spinal localization that can be challenging for even the most experienced clinicians. The following review discusses important issues that can help prevent WSS during spinal procedures.

Percutaneous placement of radiopaque markers at the pedicle of interest for preoperative localization of thoracic spine level

STUDY DESIGN

Retrospective review.

OBJECTIVE

To describe an accurate method of intraoperative localization of thoracic spine levels with percutaneously placed radiopaque markers at the pedicle of the level of interest.

SUMMARY OF BACKGROUND DATA

Intraoperative localization of thoracic spine levels can be difficult in cases without obvious vertebral body deformation (compression fracture, tumor), such as thoracic discectomy, as well as in surgery of the midthoracic spine and in the morbidly obese. Intraoperative fluoroscopy or plain radiographs are useful but can often be difficult to interpret in these cases.

METHODS

Fourteen patients requiring anterior thoracic spine surgery for thoracic disc herniations underwent preoperative localization and placement of radiopaque marker. Using standard percutaneous techniques, the radiopaque markers were placed using biplanar fluoroscopy at the pedicle at the level of interest. Eight patients subsequently underwent thoracoscopic discectomy and fusion, and 6 patients underwent mini-open thoracotomy for discectomy and fusion.

RESULTS

Placement of radiopaque markers was successfully completed without complications in all 14 patients. Intraoperatively, the markers were easy to identify and assisted in identification of the correct surgical level in all cases.

CONCLUSION

Preoperative placement of radiopaque markers at the level of interest before surgery of the thoracic spine is a safe and effective technique for avoiding wrong-level surgery in cases in which standard localization techniques may be difficult.

Intra-operative MRI-assisted spinal localization

BACKGROUND

Level localization in the thoracic spine can be problematic. We describe a new method that can be used in difficult cases, e.g., ones where lesions are mid-thoracic, small, or only visible on MRI.

METHODS

Intra-operatively, a midline incision was made and the thoracic spinous processes were exposed. A length of contrast-filled tubing was wound around the processes and the incision was temporarily closed and the patient was transferred to the radiology department for MRI under general anesthetic. Upon return to theatre, the cross sections of contrast-filled tubing and the lesion itself were visible on the MRI scan, allowing localization of the level.

FINDINGS

This method was accurate and minimized the extent of bone removal required for access.

CONCLUSIONS

This technique, while not appropriate in every case, is repeatable, and does not require specialized equipment or training. It is an extremely accurate method of localization for difficult cases.

Novel fluoroscopic technique for localization at cervicothoracic levels

STUDY DESIGN

To use a novel modified intraoperative fluoroscopic view for spinal level localization.

OBJECTIVE

To evaluate the safety and utility of the modified oblique fluoroscopic technique for intraoperative localization of distal cervical and proximal thoracic spinal levels.

SUMMARY OF BACKGROUND INFORMATION

Operative radiographic localization of the cervicothoracic spine using standard anterior-posterior and lateral views is made difficult by its anatomic relationship to the shoulder and upper chest, which produce radiographic shadowing obscuring the spine. Additional image degradation can be caused by muscular patients or those with a high body mass index. An oblique modification of the standard cross table lateral can be used to accurately identify pathologic levels at or across the cervicothoracic junction. This method distinctly demonstrates the bony lamina, which can then be used to count spinal levels. The unique feature of this technique is that the oblique angle removes the shoulder and the majority of the ribs from the active field of view, thereby producing a cleaner and more distinct image. When the gantry angle of the fluoroscope is parallel to the plane of the opposite lamina, it gives a type of "target sign" similar to the trans-pedicular image commonly used in pedicle screw placement. This radiographic sign can be easily identified and recognized across the cervicothoracic junction, even in those patients with a large body mass index or large musculature.

METHODS

Spinal level was determined intraoperatively through our oblique technique and confirmed in the same patient through standard views with retrograde counting. Postoperative imaging confirmed correct level surgery.

RESULTS

Correct spinal level identification was achieved in the distal cervical and proximal thoracic spine by implementation of our novel oblique fluoroscopy technique.

CONCLUSIONS

The modified oblique cross table fluoroscopy technique allows accurate operative localization across the cervicothoracic junction and well into the thoracic spine.

A noninvasive laser-guided preincision localizer for spine surgery

OBJECT

The design and utilization of a novel device for noninvasive preincision localization of the target spine segment during lumbar spine surgery is presented.

METHODS

The device consists of 4 low-energy laser diodes, emitting planar beams, mounted around the perimeter of a ring at right angles to each other. The beams are used to align 2 radiopaque cables hanging off the sides of the patient with the target spine segment and the radiographic source and film. The performance of the device in guiding the placement of the skin incision was prospectively evaluated in 76 consecutive patients undergoing unilateral 1-level microsurgical lumbar laminotomy. Preincision lateral radiographs obtained with the device were compared with postincision localizing radiographs in all patients.

RESULTS

In all patients, the location of the incision guided by the final preincision radiograph was found to precisely overlie the target segment as confirmed by a postincision radiograph, the latter obtained after exposure of the underlying laminae. In no instance was it necessary to extend the incision, modify the surgical trajectory, or repeat the postincision radiograph due to improper incision placement. The device's radiopaque cables were clearly visualized on radiography as they traversed the spine image, regardless of body mass index. The initial preincision radiograph based on the surgeon's estimate of the location of the target site localized the target segment in 58 patients (76.3%) and an adjacent segment in the remaining 18 patients (23.7%). Accuracy of the surgeon's initial estimate of the target site (but not accuracy of the device) was found to be inversely associated with body mass index (p < 0.001), thickness of the subcutaneous fat layer overlying the spine (p < 0.001), and presence of transitional lumbosacral anatomy (p = 0.03).

CONCLUSIONS

The localization device presented herein provides accurate noninvasive localization of the target spine segment and guides precise placement of the incision over the target segment during lumbar spine surgery.

Improving accuracy and reducing errors in spinal surgery--a new technique for thoracolumbar-level localization using computer-assisted image guidance

BACKGROUND CONTEXT

The accurate identification of the correct vertebral level during surgery remains problematic and still accounts for a significant percentage of litigation. The ideal technique for spinal-level localization would have the following characteristics: easy availability in the operating theater, lowest-possible radiation exposure for the professional team and the patient, simple technique which is easily reproducible at any time during surgery, usable with all forms of spine surgery, permanently recordable, able to be used throughout the spine, able to be easily checked by nonspecialist members of the team, and accurate.

PURPOSE

We describe a new technique for thoracolumbar-level localization, based on these principles, which uses computer-assisted image guidance.

STUDY DESIGN

Surgery technique development in clinical practice.

METHODS

The technique uses standard image intensifier radiology with FluoroNav Spine or FluoroNav MAST software on the StealthStation computer-assisted surgery system. (Medtronic Navigation, Louisville, ed) Adjacent, contiguous, images are taken in the desired plane from the reference area of the lumbosacral junction to the general area of operative interest. These images can then be displayed simultaneously on the computer screen. Use of the probe extension feature allows counting, external to the skin and drapes, from the reference level to the level of interest at any time without additional radiation exposure. Standard navigation can then be undertaken at the operative level.

RESULTS

This technique has been used in 17 cases, all of which have been undertaken in the mid- or low-thoracic and lumbar regions where the operative level is not visible on the same image intensifier image as the lumbosacral junction. All cases have undergone postoperative radiology to check the surgery level and no cases of incorrect level of surgery have occurred. No accuracy errors have developed during surgery and no complications from the reference arc have occurred.

CONCLUSIONS

This technique is indicated for level localization in the spine where the operative level cannot be visualized on the same fluoroscopy field of view as the reference level. It has a relative contraindication in the upper thoracic spine, in the very obese, and in the presence of osteoporosis where fluoroscopic imaging is difficult, although we postulate a technique using preoperative computed tomography (CT) to overcome these difficulties. This technique satisfies a number of criteria for the "ideal technique" and has advantages over current methods. A number of caveats are level localization and the use of this technique are presented.

Intraoperative localization of thoracic spine level with preoperative percutaneous placement of intravertebral polymethylmethacrylate

OBJECTIVE

To evaluate the safety and utility of preoperative vertebroplasty for intraoperative localization of thoracic spinal levels.

SUMMARY OF BACKGROUND DATA

Intraoperative fluoroscopy or plain radiographs are traditionally used to localize thoracic spine levels during thoracic spine operations. Unfortunately, such localization can occasionally be difficult in the midthoracic levels due to lack of landmarks, scapular shadows, and the body habitus of the morbidly obese. There are multiple techniques described in the literature that allow for preoperative localization of thoracic spinal levels during approaches to the posterior thoracic spine. For efficient and accurate intraoperative localization of thoracic spinal levels during anterior thoracic spine procedures, we describe a method that uses preoperative percutaneous placement of polymethylmethacrylate (PMMA) into the vertebral body using standard vertebroplasty technique.

METHODS

Four patients with morbid obesity and symptomatic thoracic disc herniations underwent preoperative vertebroplasty procedures using standard percutaneous techniques. The PMMA cement was used to expeditiously identify thoracic spinal levels of interest using intraoperative fluoroscopy.

RESULTS

All 4 patients underwent successful vertebroplasty procedures without complications. The PMMA cement was easily identified intraoperatively and led to the correct identification of the thoracic spinal levels of interest.

CONCLUSIONS

Preoperative placement of PMMA into thoracic vertebral bodies using standard vertebroplasty technique provides a safe, efficient, and reliable method of localizing thoracic spine levels intraoperatively. Such procedures can be performed in the outpatient setting and can be associated with extremely low morbidity when done by experienced practitioners. This procedure should be reserved for patients in whom a surgeon anticipates difficulty using standard radiographs or fluoroscopy to localize thoracic spinal levels intraoperatively.

Wrong disc space level surgery: medicolegal implications

BACKGROUND

Operating the wrong disc level for herniated disc disease is a rarely reported complication. However, it is considered by many a breach in the standard of care. It is not unusual for litigation to result. Sixty-nine cases of wrong disc space level surgery were identified; 68 cases were the subject of lawsuits.

METHODS

Sixty-five lawsuit outcomes were published in a national monthly newsletter of malpractice cases, Medical Malpractice Verdicts, Settlements and Experts. Two cases came from medicolegal review, one case from a news article, and one case for which no claim was made.

RESULTS

Thirty-seven cases were settled. A plaintiff verdict was rendered in 18 cases and a defense verdict in 13 cases (42% of the cases that were decided by a jury).

CONCLUSIONS

The authors summarize steps to reduce the incidence of this misadventure. The authors recommend that the patient be advised of this potential and the patient be informed of the risk factors when special circumstances exist.