Presurgical role of MRI tractography in a case of extensive cervicothoracic spinal ependymoma

The use of diffusion tensor imaging in spinal pathology: a comprehensive literature review

STUDY DESIGN

We reviewed the available literature systematically without meta-analysis following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

OBJECTIVE

To evaluate contemporary literature on use of spinal diffusion tensor imaging(sDTI) in spinal pathology.

BACKGROUND

sDTI reveals the location and functional state of critical long tracts and is a potentially useful adjunct in disease management.

METHODS

Studies were included if they presented or discussed data from investigative or therapeutic procedures involving sDTI on human subjects in the setting of surgically amenable spinal pathology. Studies were excluded if they were (1) restricted to computational models investigating parameters using data not obtained clinically, (2) about cranial DTI methods, (3) about spinal pathology data not related to surgical management, (4) discussions or overviews of methods/techniques with minimal inclusion of objective experimental or clinical data.

RESULTS

Degenerative pathologies of interest were restricted to either cervical myelopathy (22/29,75.9%) or lumbar spondylosis 7/29,24.1%). Mass-occupying lesions included intradural pathology and discussed preoperative (7/9,77.8%) and intraoperative imaging(2/9,22.2%) as an adjunct to surgery 22.2%. Traumatic pathology focused on spinal cord injury prognosis and severity grading.

CONCLUSIONS

sDTI seems useful in surgical decision making and outcome measurements and in establishing clinical prognoses over a wide range of surgical pathologies. Further research is warranted with longer follow-up and larger population sizes in a prospective and controlled protocol.

Spinal Intramedullary Meningiomas: A Systematic Review with a Case Illustration

BACKGROUND

Intramedullary meningiomas are an exceptionally rare subtype of spinal tumors, accounting for only 5% of primary spinal neoplasms. Given their scarcity and unique characteristics, understanding optimal management approaches is crucial for improved clinical decision-making. This systematic review aims to consolidate existing literature and present a detailed case illustration to enhance understanding of this uncommon spinal tumor entity.

METHODS

A systematic search adhering to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines was conducted. Eligible studies included case reports, case series, cohort studies, reviews, and meta-analyses. Data extraction and synthesis focused on demographic characteristics, tumor location, clinical presentation, imaging findings, surgical interventions, histopathological features, and outcomes.

RESULTS

A total of 15 high-quality scientific articles were included in the systematic review, providing insights into various aspects of intramedullary meningiomas. Demographic analysis revealed a broad age distribution with an equal gender distribution among affected patients. Common clinical presentations included difficulty walking, sensory disturbances, spastic paraparesis, and urinary incontinence. Neuroimaging findings demonstrated heterogeneous signal intensity variations on T1- and T2-weighted images, with variable enhancement patterns on gadolinium-enhanced images. Surgical interventions, predominantly total resection, resulted in favorable postoperative outcomes in most cases.

CONCLUSIONS

Intramedullary meningiomas pose diagnostic and therapeutic challenges due to their rarity and unique characteristics. Tailored surgical approaches, incorporating techniques such as intraoperative neurophysiological monitoring and fluorescence-aided resection, are crucial for minimizing neurological deficits and optimizing patient outcomes. Despite their infrequency, recognizing intramedullary meningiomas in the differential diagnosis of spinal tumors is essential for prompt diagnosis and timely intervention, ultimately improving patient prognosis.

Diffusion Weighted Imaging in Spine Tumors

Diffusion weighted imaging (DWI) has developed into a powerful tool for the evaluation of spine tumors, particularly for the assessment of vertebral marrow lesions and intramedullary tumors. Advances in magnetic resonance techniques have improved the quality of spine DWI and diffusion tensor imaging (DTI) in recent years, with increased reproducibility and utilization. DTI, with quantitative parameters such as fractional anisotropy and qualitative visual assessment of nerve fiber tracts, can play a valuable role in the evaluation and surgical planning of spinal cord tumors. These widely available techniques can be used to enhance the diagnostic evaluation of spinal tumors.

Full cervical cord tractography: A new method for clinical use

Despite recent improvements in diffusion-weighted imaging, spinal cord tractography is not used in routine clinical practice because of difficulties in reconstructing tractograms, with a pertinent tri-dimensional-rendering, in a long post-processing time. We propose a new full tractography approach to the cervical spinal cord without extensive manual filtering or multiple regions of interest seeding that could help neurosurgeons manage various spinal cord disorders. Four healthy volunteers and two patients with either cervical intramedullary tumors or spinal cord injuries were included. Diffusion-weighted images of the cervical spinal cord were acquired using a Philips 3 Tesla machine, 32 diffusion directions, 1,000 s/mm²b-value, 2 × 2 × 2 mm voxel size, reduced field-of-view (ZOOM), with two opposing phase-encoding directions. Distortion corrections were then achieved using the FSL software package, and tracking of the full cervical spinal cord was performed using the DSI Studio software (quantitative anisotropy-based deterministic algorithm). A unique region of avoidance was used to exclude everything that is not of the nervous system. Fiber tracking parameters used adaptative fractional anisotropy from 0.015 to 0.045, fiber length from 10 to 1,000 mm, and angular threshold of 90°. In all participants, a full cervical cord tractography was performed from the medulla to the C7 spine level. On a ventral view, the junction between the medulla and spinal cord was identified with its pyramidal bulging, and by an invagination corresponding to the median ventral sulcus. On a dorsal view, the fourth ventricle—superior, middle, and inferior cerebellar peduncles—was seen, as well as its floor and the obex; and gracile and cuneate tracts were recognized on each side of the dorsal median sulcus. In the case of the intramedullary tumor or spinal cord injury, the spinal tracts were seen to be displaced, and this helped to adjust the neurosurgical strategy. This new full tractography approach simplifies the tractography pipeline and provides a reliable 3D-rendering of the spinal cord that could help to adjust the neurosurgical strategy.

Surgical approaches to intramedullary spinal cord astrocytomas in the age of genomics

Intramedullary astrocytomas represent approximately 30%–40% of all intramedullary tumors and are the most common intramedullary tumor in children. Surgical resection is considered the mainstay of treatment in symptomatic patients with neurological deficits. Gross total resection (GTR) can be difficult to achieve as astrocytomas frequently present as diffuse lesions that infiltrate the cord. Therefore, GTR carries a substantial risk of new post-operative deficits. Consequently, subtotal resection and biopsy are often the only surgical options attempted. A midline or paramedian sulcal myelotomy is frequently used for surgical resection, although a dorsal root entry zone myelotomy can be used for lateral tumors. Intra-operative neuromonitoring using D-wave integrity, somatosensory, and motor evoked potentials is critical to facilitating a safe resection. Adjuvant radiation and chemotherapy, such as temozolomide, are often administered for high-grade recurrent or progressive lesions; however, consensus is lacking on their efficacy. Biopsied tumors can be analyzed for molecular markers that inform clinicians about the tumor’s prognosis and response to conventional as well as targeted therapeutic treatments. Stratification of intramedullary tumors is increasingly based on molecular features and mutational status. The landscape of genetic and epigenetic mutations in intramedullary astrocytomas is not equivalent to their intracranial counterparts, with important difference in frequency and type of mutations. Therefore, dedicated attention is needed to cohorts of patients with intramedullary tumors. Targeted therapeutic agents can be designed and administered to patients based on their mutational status, which may be used in coordination with traditional surgical resection to improve overall survival and functional status.

Diffusion Tensor Imaging of the Spinal Cord

Spinal cord often is regarded as one of the last territories in the central nervous system where diffusion tensor imaging (DTI) can be used to probe white matter architecture. This article reviews current progress in spinal cord DTI, starting with anatomic properties and technical challenges that make spinal cord DTI a difficult task. Several possibilities offered by advanced pulse sequences that might overcome the difficulties are addressed, with associated trade-offs and limitations. Potential clinical assistance also is discussed in various spinal cord pathologies, such as myelopathy due to external compression, spinal cord tumors, acute ischemia, traumatic injury, and so forth.

Sodium Fluorescein for Spinal Intradural Tumors

Technological innovations in spinal intradural tumor surgery simplify treatment. Surgical treatment of cranial benign and malignant pathologies under microscope with sodium (Na)-fluorescein guidance has often been reported, but few studies have focused on spinal intradural tumors. We aimed to investigate the usefulness of Na-fluorescein under yellow filter in intradural spinal tumor surgery by retrospectively reviewing cases involving intramedullary and extramedullary tumors operated under the guidance of Na-fluorescein. Forty-nine adult patients with a diagnosis of spinal intradural tumor operated under a yellow filter (560 nm) microscope using Na-fluorescein dye were included in the study. Demographic data, such as age and sex, neurological status, extent of tumor resection, histopathological diagnosis, Na-fluorescein staining pattern, and its usefulness during surgery were noted and statistically analyzed. Of all recruited patients, 26 women (53.1%) and 23 men (46.9%), were included for analysis. The age range of the patients was 18–64 years, with a mean age of 41.6 ± 13.9. An intradural intramedullary mass was found in 30.6% (n = 15) of the patients, and an intradural extramedullary mass in 69.4% (n: 34). While Na-fluorescein staining was homogeneous in all intradural extramedullary tumors, 73.3% (n: 11) of intradural intramedullary tumors were homogeneous, and 13.3% (n: 2) moderately heterogeneous. In the whole study group, the Na-fluorescein staining pattern was helpful in surgical resection in 47 cases (95.9%). While 34/34 (100%) found it helpful for extramedullary tumors, 13/15 (86.7%) did in intramedullary tumors, and for 2/15 (13.3%) it was not. In conclusion, Na-fluorescein helps in distinguishing tumor from healthy tissue in intradural extramedullary and intramedullary tumor surgery under a yellow filter microscope in most cases, thus providing convenient assistance to surgeons.