Automated measurement of anteroposterior diameter and foraminal widths in MRI images for lumbar spinal stenosis diagnosis.

Lumbar Spinal Stenosis causes low back pain through pressures exerted on the spinal nerves. This can be verified by measuring the anteroposterior diameter and foraminal widths of the patient's lumbar spine. Our goal is to develop a novel strategy for assessing the extent of Lumbar Spinal Stenosis by automatically calculating these distances from the patient's lumbar spine MRI. Our method starts with a semantic segmentation of T1- and T2-weighted composite axial MRI images using SegNet that partitions the image into six regions of interest. They consist of three main regions-of-interest, namely the Intervertebral Disc, Posterior Element, and Thecal Sac, and three auxiliary regions-of-interest that includes the Area between Anterior and Posterior elements. A novel contour evolution algorithm is then applied to improve the accuracy of the segmentation results along important region boundaries. Nine anatomical landmarks on the image are located by delineating the region boundaries found in the segmented image before the anteroposterior diameter and foraminal widths can be measured. The performance of the proposed algorithm was evaluated through a set of experiments on the Lumbar Spine MRI dataset containing MRI studies of 515 patients. These experiments compare the performance of our contour evolution algorithm with the Geodesic Active Contour and Chan-Vese methods over 22 different setups. We found that our method works best when our contour evolution algorithm is applied to improve the accuracy of both the label images used to train the SegNet model and the automatically segmented image. The average error of the calculated right and left foraminal distances relative to their expert-measured distances are 0.28 mm (p = 0.92) and 0.29 mm (p = 0.97), respectively. The average error of the calculated anteroposterior diameter relative to their expert-measured diameter is 0.90 mm (p = 0.92). The method also achieves 96.7% agreement with an expert opinion on determining the severity of the Intervertebral Disc herniations.

Application of intraoperative electrophysiological monitoring in vertebral canal decompression surgery for acute spinal cord injury.

OBJECTIVE: This study aimed to evaluate the joint monitoring of somatosensory evoked potentials (SEPs) and motor evoked potentials (MEPs) in vertebral canal decompression surgery for acute spinal cord injury. METHODS: Twenty-four patients, who were admitted to the hospital for the surgical treatment of spinal cord injury with SEP and MEP monitoring, were assigned to the intraoperative monitoring group (group I). In addition, 24 patients who were admitted to the hospital for the surgical treatment of spinal cord injury without SEP or MEP monitoring were assigned to the control group (group C). RESULTS: In group I, there were significant changes before and after decompression surgery in the P40 latency and amplitude, and in the latency of MEP in the abductor hallucis brevis (AHB), in patients with improved spinal nerve function following surgery. In contrast, there were no significant differences in the P40 latency or amplitude, or the latency of MEP in the AHB, in patients who showed no improvement after surgery. CONCLUSION: In vertebral canal decompression surgery for acute spinal cord injury, the application of joint MEP and SEP monitoring can timely reflect changes in spinal cord function.

Cerebrospinal fluid leak presented with the C1-C2 sign caused by spinal canal stenosis: a case report.

BACKGROUND: Intracranial hypotension is a disorder characterized by low cerebrospinal fluid (CSF) pressure typically caused by loss of CSF. Although some mechanisms account for the CSF leakage have been elucidated, spinal canal stenosis has never been reported as a pathological cause of intracranial hypotension. C1-C2 sign is a characteristic imaging feature, which indicates CSF collection between the spinous processes of C1 and C2, occasionally observed on magnetic resonance imaging (MRI) in patients with intracranial hypotension. CASE PRESENTATION: A 58-year-old man was presented to our institute with complaints of posterior cervical pain persisting for 3 months, along with numbness and muscle weakness of extremities. A fat suppression T2-weighted image of MRI illustrated fluid collection in the retrospinal region at C1-C2 level, and an 111In-DTPA cisternoscintigram clearly revealed the presence of CSF leakage into the same region. The MRI also showed stenosis in spinal canal at C3/4 level, and a computed tomography (CT) myelogram suggested a blockage at the same level. We gave a diagnosis as intracranial hypotension due to the CSF leakage, which might be caused by the spinal canal stenosis at C3/4 level. Despite 72 h of conservative therapy, a brain CT showed the development of bilateral subdural hematomas. We, therefore, performed burr-hole drainage of the subdural hematoma, blood-patch therapy at C1/2 level, and laminoplasty at C3-4 at the same time. Improvement of symptoms and imaging features which suggested the CSF leak and subdural hematoma were obtained post-operatively. CONCLUSION: The present case suggested the mechanism where the CSF leakage was revealed as fluid collection in the retrospinal region at C1-C2 level. Increased intradural pressure due to the spinal canal stenosis resulted in dural tear. CSF leaked into the epidural space and subsequently to the retrospinal region at C1-C2 level, due to the presence of spinal canal stenosis caudally as well as the vulnerability of the tissue structure in the retrospinal region at C1-C2 level. Thus, our theory supports the mechanisms of previously reported CSF dynamics associated to C1-C2 sign, and also, we suggest spinal canal stenosis as a novel etiology of intracranial hypotension.

Axial loading during MRI reveals insufficient effect of percutaneous interspinous implants (Aperius™ PerCLID™) on spinal canal area.

PURPOSE: To evaluate the effect on the spinal canal at the treated and adjacent level(s), in patients treated for lumbar spinal stenosis (LSS) with percutaneous interspinous process device (IPD) Aperius™ or open decompressive surgery (ODS), using axial loading of the spine during MRI (alMRI). MATERIALS: Nineteen LSS patients (mean age 67 years, range 49-78) treated with IPDs in 29 spine levels and 13 LSS patients (mean age 63 years, range 46-76) operated with ODS in 22 spine levels were examined with alMRI pre- and 3 months postoperatively. Radiological effects were evaluated by measuring the dural sac cross-sectional area (DSCSA) and by morphological grading of nerve root affection. RESULTS: For the IPD group, no DSCSA increase was observed at the operated level (p = 0.42); however, a decrease was observed in adjacent levels (p = 0.05). No effect was seen regarding morphological grading (operated level: p = 0.71/adjacent level: p = 0.94). For the ODS group, beneficial effects were seen for the operated level, both regarding DSCSA (p < 0.001) and for morphological grading (p < 0.0001). No changes were seen for adjacent levels (DSCSA; p = 0.47/morphological grading: p = 0.95). Postoperatively, a significant difference between the groups existed at the operated level regarding both evaluated parameters (p < 0.003). CONCLUSIONS: With the spine imaged in an axial loaded position, no significant radiological effects of an IPD could be detected postoperatively at the treated level, while increased DSCSA was displayed for the ODS group. In addition, reduced DSCSA in adjacent levels was detected for the IPD group. Thus, the beneficial effects of IPD implants on the spinal canal must be questioned. These slides can be retrieved under Electronic Supplementary Material.

Minimally invasive surgery for degenerative spondylolisthesis: transforaminal or oblique lumbar interbody fusion.

Aim: To compare the outcomes of minimally invasive surgery (MIS) for degenerative spondylolisthesis transforaminal lumbar interbody fusion (TLIF) and oblique lumbar interbody fusion (OLIF). Materials & methods: The clinical and surgical characteristics and outcomes of 38 patients with MIS-OLIF and 55 with MIS-TLIF were retrospectively evaluated. Results: Procedures and hospital stay were shorter and blood loss was less, with MIS-OLIF than with MIS-OLIF. The clinical and radiographic outcomes were similar. Postoperative changes in disk height and foraminal dimension were greater and patient satisfaction was better with MIS-OLIF than with MIS-TLIF. Conclusion: The clinical findings associated with the two procedures were similar; but patients preferred MIS-OLIF, which is less invasive, to MIS-TLIF. Clinical trial registration number: ChiCTR1800019443.

Discectomía, artrodesis intersomática y estabilización en mielopatía espondilótica cervical. Presentación de un caso / Discectomy, artrodesis and stabilization in cervical spondylotic myelopathy. Presentation of a case

RESUMEN Las alteraciones degenerativas de la columna se engloban en el término de espondilosis cervical. La mielopatía espondilótica cervical (MEC) es la forma más común de disfunción del cordón espinal en mayores de 55 años. Se considera la intervención quirúrgica en la mayoría de los casos de mielopatía cervical espondilótica evidente desde el punto de vista clínico, dado el riesgo de deterioro neurológico. En la mayoría de los casos de mielopatía cervical, la descompresión de la médula espinal genera estabilización o mejoría de la función de los haces largos medulares. La función es mejor cuando se restablecen bien las dimensiones del conducto vertebral después de la descompresión, cuando la descompresión es más precoz y cuando no hay comorbilidad considerable (AU).

ABSTRACT The degenerative alterations of the column are included in the term of cervical espondilosis. The cervical spondylotic myelopathy it is the form more common of disfuntion of the spinal cord in bigger than 55 years. It is considered the surgical intervention in most of the cases of cervical spondylotic myelopathy evident from the clinical, given point of view the risk of neurological deterioration. In most of the cases of cervical myelopathy, the decompression of the spinal marrow generates stabilization or improvement of the function of the medullary long sheaves. The function is better when they recover well the dimensions of the vertebral conduit after the decompression, when the decompression is more precocious and when there is not considerable comorbility (AU).

Discectomía, artrodesis intersomática y estabilización en mielopatía espondilótica cervical. Presentación de un caso / Discectomy, artrodesis and stabilization in cervical spondylotic myelopathy. Presentation of a case

RESUMEN Las alteraciones degenerativas de la columna se engloban en el término de espondilosis cervical. La mielopatía espondilótica cervical (MEC) es la forma más común de disfunción del cordón espinal en mayores de 55 años. Se considera la intervención quirúrgica en la mayoría de los casos de mielopatía cervical espondilótica evidente desde el punto de vista clínico, dado el riesgo de deterioro neurológico. En la mayoría de los casos de mielopatía cervical, la descompresión de la médula espinal genera estabilización o mejoría de la función de los haces largos medulares. La función es mejor cuando se restablecen bien las dimensiones del conducto vertebral después de la descompresión, cuando la descompresión es más precoz y cuando no hay comorbilidad considerable.

ABSTRACT The degenerative alterations of the column are included in the term of cervical espondilosis. The cervical spondylotic myelopathy it is the form more common of disfuntion of the spinal cord in bigger than 55 years. It is considered the surgical intervention in most of the cases of cervical spondylotic myelopathy evident from the clinical, given point of view the risk of neurological deterioration. In most of the cases of cervical myelopathy, the decompression of the spinal marrow generates stabilization or improvement of the function of the medullary long sheaves. The function is better when they recover well the dimensions of the vertebral conduit after the decompression, when the decompression is more precocious and when there is not considerable comorbility.

[Minimally invasive decompression techniques for spinal cord stenosis]. / Minimal-invasive Dekompressionsverfahren der Spinalkanalstenose.

BACKGROUND: Lumbar spinal canal stenosis is frequently found among elderly patients and significantly limits their quality of life. Non-surgical therapy is an initial treatment option; however, it does not eliminate the underlying pathology. Surgical decompression of the spinal canal has now become the treatment of choice. OBJECTIVE: Minimalization of surgical approach strategies with maintaining sufficient decompression of the spinal canal and avoiding disadvantages of macrosurgical techniques, monolateral paravertebral approach with bilateral intraspinal decompression, specific surgical techniques. MATERIALS AND METHODS: Minimally invasive decompression techniques using a microscope or an endoscope are presented and different surgical strategies depending on both the extent (mono-, bi-, and multisegmental) and the location of the stenosis (intraspinal central, lateral recess, foraminal) are described. RESULTS: Minimally invasive microscopic or endoscopic decompression procedures enable sufficient widening of the spinal canal. Disadvantages of macrosurgical procedures (e. g., postoperative instability) can be avoided. The complication spectrum overlaps partially with that of macrosurgical interventions, albeit with significantly less marked severity. Subjective patient outcome is clearly improved. CONCLUSIONS: Referring to modern minimally invasive decompression procedures, surgery of lumbar spinal canal stenosis represents a rational and logical treatment alternative, since causal treatment of the pathology is only possible with surgery.

Cerebrospinal fluid volumetric net flow rate and direction in idiopathic normal pressure hydrocephalus.

The aim of the present study was to examine cerebrospinal fluid (CSF) volumetric net flow rate and direction at the cranio-cervical junction (CCJ) and cerebral aqueduct in individuals with idiopathic normal pressure hydrocephalus (iNPH) using cardiac-gated phase-contrast magnetic resonance imaging (PC-MRI). An in-depth, pixel-by-pixel analysis of regions of interest from the CCJ and cerebral aqueduct, respectively, was done in 26 iNPH individuals, and in 4 healthy subjects for validation purposes. Results from patients were compared with over-night measurements of static and pulsatile intracranial pressure (ICP). In iNPH, CSF net flow at CCJ was cranially directed in 17/22 as well as in 4/4 healthy subjects. Estimated daily CSF volumetric net flow rate at CCJ was 6.9 ±â€¯9.9 L/24 h in iNPH patients and 4.5 ±â€¯5.0 L/24 h in healthy individuals. Within the cerebral aqueduct, the CSF net flow was antegrade in 7/21 iNPH patients and in 4/4 healthy subjects, while it was retrograde (i.e. towards ventricles) in 14/21 iNPH patients. Estimated daily CSF volumetric net flow rate in cerebral aqueduct was 1.1 ±â€¯2.2 L/24 h in iNPH while 295 ±â€¯53 mL/24 h in healthy individuals. Magnitude of cranially directed CSF net flow in cerebral aqueduct was highest in iNPH individuals with signs of impaired intracranial compliance. The study results indicate CSF flow volumes and direction that are profoundly different from previously assumed. We hypothesize that spinal CSF formation may serve to buffer increased demand for CSF flow through the glymphatic system during sleep and during deep inspiration to compensate for venous outflow.

Effects of spine loading in a patient with post-decompression lumbar disc herniation: observations using an open weight-bearing MRI.

PURPOSE: Our objective was to use an open weight-bearing MRI to identify the effects of different loading conditions on the inter-vertebral anatomy of the lumbar spine in a post-discectomy recurrent lumbar disc herniation patient. METHODS: A 43-year-old male with a left-sided L5-S1 post-decompression re-herniation underwent MR imaging in three spine-loading conditions: (1) supine, (2) weight-bearing on standing (WB), and (3) WB with 10 % of body mass axial loading (WB + AL) (5 % through each shoulder). A segmentation-based proprietary software was used to calculate and compare linear dimensions, angles and cross sections across the lumbar spine. RESULTS: The L5 vertebrae showed a 4.6 mm posterior shift at L5-S1 in the supine position that changed to an anterior translation >2.0 mm on WB. The spinal canal sagittal thickness at L5-S1 reduced from supine to WB and WB + AL (13.4, 10.6, 9.5 mm) with corresponding increases of 2.4 and 3.5 mm in the L5-S1 disc protrusion with WB and WB + AL, respectively. Change from supine to WB and WB + AL altered the L5-S1 disc heights (10.2, 8.6, 7.0 mm), left L5-S1 foramen heights (12.9, 11.8, 10.9 mm), L5-S1 segmental angles (10.3°, 2.8°, 4.3°), sacral angles (38.5°, 38.3°, 40.3°), L1-L3-L5 angles (161.4°, 157.1°, 155.1°), and the dural sac cross sectional areas (149, 130, 131 mm2). Notably, the adjacent L4-L5 segment demonstrated a retro-listhesis >2.3 mm on WB. CONCLUSION: We observed that with weight-bearing, measurements indicative of spinal canal narrowing could be detected. These findings suggest that further research is warranted to determine the potential utility of weight-bearing MRI in clinical decision-making.

Actualización en la fisiopatología y manejo de traumatismo raquimedular: revisión bibliográfica / Actualization in pathophysiology and management of traumatic spinal cord injury: literature review

El Traumatismo Raquimedular (TRM) implica todas las lesiones traumáticas que dañan los huesos, ligamentos, músculos, cartílagos, estructuras vasculares, radiculares o meníngeas a cualquier nivel de la médula espinal. Las consecuencias personales, familiares, sociales y económicas de esta enfermedad, hacen que sea un tema relevante en la actualidad. El propósito de esta revisión es entregar al lector las herramientas elementales sobre el TRM, y está principalmente enfocada en el tratamiento, el cual se aborda estrechamente relacionado con la fisiopatología para comprender los mecanismos moleculares y biomecánicos de trauma, incluyendo sus complicaciones y el manejo de éstas. Respecto al tratamiento del TRM, se aborda la evidencia que ofrecen las terapias actualmente validadas y las aún controversiales, incluyendo los glucocorticoides, la reducción cerrada y la cirugía precoz. Además las terapias emergentes como la hipotermia terapéutica, los nuevos agentes neuroprotectores que se encuentran en fases preclínicas y clínicas de estudio como el riluzol, la minociclina, el litio, los antagonistas opioides, entre otros, y los agentes neurorregenerativos como el Cethrin y el Anti-Nogo que han mostrado buenos resultados en la recuperación neurológica. Las recomendaciones actuales respecto a la terapia con células madre y subtipos de células madre en la actualidad, es que deben llevarse a cabo sólo en el contexto de ensayos clínicos. Aunque aún no existen terapias que permitan la recuperación neurológica completa en todos o la mayoría de los pacientes, las terapias emergentes prevén un futuro promisorio en los resultados clínicos de los pacientes con TRM.

The traumatic spinal cord injury (TSCI) involves all traumatic injuries that harm the bones, ligaments, muscles, cartilage, vascular, radicular or meningeal structures, at any level of the spinal cord. The personal, family, social and economic consequences of this disease, make it an important issue today. The purpose of this review is to provide the reader, the basic tools of the TRM, and it is mainly aimed at the treatment, which it approaches closely related to the pathophysiology, to understand the molecular and biomechanical mechanisms of trauma, including its complications and his management. Regarding treatment of TSCI, the evidence offered by currently validated and controversial therapies is discussed, including glucocorticoids, closed reduction and early surgery. Also emerging therapies such as therapeutic hypothermia, new neuroprotective agents currently in preclinical and clinical phases as riluzole, minocycline, lithium, opioid antagonists, among others, and neuroregenerative agents like Cethrin and Anti- Nogo that have shown good results in neurological recovery. Current recommendations for therapy with stem cells and subtype stem cell, is that only should be carried out in the context of clinical trials. Although there are not still therapies that allow full neurological recovery in all or most patients, emerging therapies provide a promising future in the clinical outcomes of patients with TRM.

Periosteal chondroma with spinal cord compression in the thoracic spinal canal: a case report.

Periosteal chondroma is a very unusual cartilaginous neoplasm of the spinal canal. We herein report a case of periosteal chondroma in a 41-year-old male who presented with gait disturbance and paresthesia of both lower extremities. Magnetic resonance (MR) images showed an extradural mass which caused compression of the spinal cord at the T5/6 level. The mass showed iso-signal intensity on T1-weighted images, high signal intensity on T2-weighted images, and nodular and peripheral rim enhancement on post-contrast T1-weighted images. Computed tomography (CT) images showed a mass with punctate calcifications and extension into the left T5/6 neural foramen. MR and CT images showed extrinsic cortical bone erosion of the posterior inferior body of T5 and superior pedicle of T6, bone remodeling with overhanging margins, and sclerosis adjacent to the tumor. The patient underwent a complete excision of the mass by left T5/6 hemi-laminectomy and exhibited complete resolution of his symptoms. Histopathologic examination revealed periosteal chondroma. Tumor recurrence was not recorded during the 18-month follow-up period.

Kinematic analysis of cervical spine canal diameter and its association with grade of degeneration.

OBJECTIVES: To investigate the cervical spinal canal diameters variance under positional MRI, and also the relationship between cervical canal diameter variance rate and grade of degeneration. METHODS: From January 2013 to January 2015, a consecutive of 273 symptomatic patients (166 males and 207 females) with an average age of 44.6 years (range 21-89 years) underwent positional cervical MRI. T2-weighted sagittal images of 1638 cervical intervertebral discs from 273 subjects were classified into five grades. The canal diameter and canal diameter variance rate at three positions and their comparison among five grade of degeneration were evaluated. The measurements were tabulated and analyzed using SPSS. 13.0. p values less than 0.05 were considered to indicate a statistically significant difference. RESULTS: The sagittal cervical canal diameter at the C5/6 level were the smallest compared with the other levels regardless of neutral, flexion or extension positions, C5/6 level had the largest canal diameter variance rate in both flexion and extension (8.14 ∓ 0.38 and 7.81 ∓ 0.31 %, respectively), second was C4/5 level (7.65 ∓ 0.39 and 7.67 ∓ 0.32 %, respectively). A total of 1638 discs were classified into 5 groups, each level showed the similar tendency that no matter what position, with the increasing grade of degenerative disc degree, spine canal diameter decreased gradually. For C5/6 under extension and flexion position, significant difference was also noted between grade 2 and 3; For C4/5 under extension position, significant difference existed between grade 1 and 2, grade 1 and 3, while under flexion position, significant difference existed between grade 2 and 4, and the results also showed no significant difference at the same degree of degeneration on both levels between extension and flexion position. CONCLUSIONS: C5/6 and C4/5 is of higher risk of suffering SCI than other levels, C4/5 level predispose SCI at earlier stage than C5/6, patients presenting with intermediate signal and slight decreased disc height on T2 weighted MRI at C4/5 level should be paid attention.

Transient pressure changes in the vertebral canal during whiplash motion--A hydrodynamic modeling approach.

In vehicle collisions, the occupant's torso is accelerated in a given direction while the unsupported head tends to lag behind. This mechanism results in whiplash motion to the neck. In whiplash experiments conducted for animals, pressure transients have been recorded in the spinal canal. It was hypothesized that the transients caused dorsal root ganglion dysfunction. Neck motion introduces volume changes inside the vertebral canal. The changes require an adaptation which is likely achieved by redistribution of blood volume in the internal vertebral venous plexus (IVVP). Pressure transients then arise from the rapid redistribution. The present study aimed to explore the hypothesis theoretically and analytically. Further, the objectives were to quantify the effect of the neck motion on the pressure generation and to identify the physical factors involved. We developed a hydrodynamic system of tubes that represent the IVVP and its lateral intervertebral vein connections. An analytical model was developed for an anatomical geometrical relation that the venous blood volume changes with respect to the vertebral angular displacement. This model was adopted in the hydrodynamic tube system so that the system can predict the pressure transients on the basis of the neck vertebral motion data from a whiplash experiment. The predicted pressure transients were in good agreement with the earlier experimental data. A parametric study was conducted and showed that the system can be used to assess the influences of anatomical geometrical properties and vehicle collision severity on the pressure generation.

Flexible active electrode arrays with ASICs that fit inside the rat's spinal canal.

Epidural spinal cord electrical stimulation (ESCS) has been used as a means to facilitate locomotor recovery in spinal cord injured humans. Electrode arrays, instead of conventional pairs of electrodes, are necessary to investigate the effect of ESCS at different sites. These usually require a large number of implanted wires, which could lead to infections. This paper presents the design, fabrication and evaluation of a novel flexible active array for ESCS in rats. Three small (1.7 mm(2)) and thin (100 µm) application specific integrated circuits (ASICs) are embedded in the polydimethylsiloxane-based implant. This arrangement limits the number of communication tracks to three, while ensuring maximum testing versatility by providing independent access to all 12 electrodes in any configuration. Laser-patterned platinum-iridium foil forms the implant's conductive tracks and electrodes. Double rivet bonds were employed for the dice microassembly. The active electrode array can deliver current pulses (up to 1 mA, 100 pulses per second) and supports interleaved stimulation with independent control of the stimulus parameters for each pulse. The stimulation timing and pulse duration are very versatile. The array was electrically characterized through impedance spectroscopy and voltage transient recordings. A prototype was tested for long term mechanical reliability when subjected to continuous bending. The results revealed no track or bond failure. To the best of the authors' knowledge, this is the first time that flexible active electrode arrays with embedded electronics suitable for implantation inside the rat's spinal canal have been proposed, developed and tested in vitro.

Does Co-Existing Lumbar Spinal Canal Stenosis Impair Functional Outcomes and Activity Levels after Primary Total Hip Arthroplasty?

Degenerative lumbar spinal stenosis (LSS) is a cause for substantial morbidity in the elderly population: many often undergo total hip arthroplasty for associated hip arthritis. With a matched cohort we investigated the effect of co-existing LSS on aseptic survivorship, functional outcomes, activity levels, overall subjective physical and mental health status, and satisfaction rates in patients undergoing primary THA. The aseptic-implant survivorship was similar in LSS and non-stenosis cohort. Although both cohorts significantly improved, the LSS cohort achieved lower improvements in HHS, UCLA, SF-36 physical, and satisfaction rates than the matched non-stenotic cohort. Surgeons should consider cautioning patients with LSS that although they can expect relief of their arthritic symptoms following THA, they may continue to expect limitations in function, physical-status, activity-levels, and satisfaction rates.

Numerical simulations of the pulsating flow of cerebrospinal fluid flow in the cervical spinal canal of a Chiari patient.

The flow of cerebrospinal fluid (CSF) in a patient-specific model of the subarachnoid space in a Chiari I patient was investigated using numerical simulations. The pulsating CSF flow was modeled using a time-varying velocity pulse based on peak velocity measurements (diastole and systole) derived from a selection of patients with Chiari I malformation. The present study introduces the general definition of the Reynolds number to provide a measure of CSF flow instability to give an estimate of the possibility of turbulence occurring in CSF flow. This was motivated by the fact that the combination of pulsating flow and the geometric complexity of the spinal canal may result in local Reynolds numbers that are significantly higher than the commonly used global measure such that flow instabilities may develop into turbulent flow in these regions. The local Reynolds number was used in combination with derived statistics to characterize the flow. The results revealed the existence of both local unstable regions and local regions with velocity fluctuations similar in magnitude to what is observed in fully turbulent flows. The results also indicated that the fluctuations were not self-sustained turbulence, but rather flow instabilities that may develop into turbulence. The case considered was therefore believed to represent a CSF flow close to transition.

Frequency, timing, and predictors of neurological dysfunction in the nonmyelopathic patient with cervical spinal cord compression, canal stenosis, and/or ossification of the posterior longitudinal ligament.

STUDY DESIGN: Systematic review and survey. OBJECTIVE: To perform an evidence synthesis of the literature and obtain information from the global spine care community assessing the frequency, timing, and predictors of symptom development in patients with radiographical evidence of cervical spinal cord compression, spinal canal narrowing, and/or ossification of posterior longitudinal ligament (OPLL) but no symptoms of myelopathy. SUMMARY OF BACKGROUND DATA: Evidence for a marker to predict symptom development remains sparse, and there is controversy surrounding the management of asymptomatic patients. METHODS: We conducted a systematic review of the English language literature and an international survey of spine surgeons to answer the following key questions in patients with radiographical evidence of cervical spinal cord compression, spinal canal narrowing, and/or OPLL but no symptoms of myelopathy: (1) What are the frequency and timing of symptom development? (2) What are the clinical, radiographical, and electrophysiological predictors of symptom development? (3) What clinical and/or radiographical features influence treatment decisions based on an international survey of spine care professionals? RESULTS: The initial literature search yielded 388 citations. Applying the inclusion/exclusion criteria narrowed this to 5 articles. Two of these dealt with the same population. For patients with spinal cord compression secondary to spondylosis, one study reported the frequency of myelopathy development to be 22.6%. The presence of symptomatic radiculopathy, cervical cord hyperintensity on magnetic resonance imaging, and prolonged somatosensory- and motor-evoked potentials were reported in one study as significant independent predictors of myelopathy development. In contrast, the lack of magnetic resonance imaging hyperintensity was found to be a positive predictor of early myelopathy development (≤ 12-mo follow-up). For subjects with OPLL, frequency of myelopathy development was reported in 3 articles and ranged from 0.0% to 61.5% of subjects. One of these studies reported canal stenosis of 60% or more, lateral deviated OPLL, and increased cervical range of motion as significant predictors of myelopathy development. In a survey of 774 spine surgeons, the majority deemed the presence of clinically symptomatic radiculopathy to predict progression to myelopathy in nonmyelopathic patients with cervical stenosis. Survey responses pertaining to 3 patient case vignettes are also presented and discussed in the context of the current literature. CONCLUSION: On the basis of these results, we provide a series of evidence-based recommendations related to the frequency, timing, and predictors of myelopathy development in asymptomatic patients with cervical stenosis secondary to spondylosis or OPLL. Future prospective studies are required to refine our understanding of this topic. EVIDENCE-BASED CLINICAL RECOMMENDATIONS: RECOMMENDATION: Patients with cervical canal stenosis and cord compression secondary to spondylosis, without clinical evidence of myelopathy, and who present with clinical or electrophysiological evidence of cervical radicular dysfunction or central conduction deficits seem to be at higher risk for developing myelopathy and should be counseled to consider surgical treatment. OVERALL STRENGTH OF EVIDENCE: Moderate. STRENGTH OF RECOMMENDATION: Strong. SUMMARY STATEMENTS: STATEMENT 1: On the basis of the current literature, for patients with cervical canal stenosis and cord compression secondary to spondylosis, without clinical evidence of myelopathy, approximately 8% at 1-year follow-up and 23% at a median of 44-months follow-up develop clinical evidence of myelopathy. STATEMENT 2: For patients with cervical canal stenosis and cord compression secondary to spondylosis, without clinical evidence of myelopathy, the absence of magnetic resonance imaging intramedullary T2 hyperintensity has been shown to predict early myelopathy development (<12-mo follow-up) and the presence of such signal has been shown to predict late myelopathy development (mean 44-mo follow-up). In light of this discrepancy, no definite recommendation can be made surrounding the utility of this finding in predicting myelopathy development. STATEMENT 3: For patients with OPLL but without myelopathy, no recommendation can be made regarding the incidence or predictors of progression to myelopathy.

Compressive loading of the spine may affect the spinal canal encroachment of burst fractures.

STUDY DESIGN: Spinal canal encroachment of burst fractures under different compressive loading. OBJECTIVE: To assess whether the application of different compressive loads affect the spinal canal encroachment (SCE) of thoracolumbar burst fractures and to relate any significant encroachment differences to the fracture morphology. SUMMARY OF BACKGROUND DATA: The SCE is an important part of the evaluation process of thoracolumbar burst fractures. It is, however, not well understood how a variation in spinal internal loads resulting from a change in patient posture may affect the SCE after a burst fracture. The application of a compressive load on fractured vertebrae may displace bony fragments further into the canal and increase the encroachment. METHODS: Ten thoracolumbar functional spinal units harvested from mature minipigs and compressed to create burst fractures were imaged by computed tomography under 3 loading conditions: without compressive force and with 2 compressive forces analogous to the load expected in vivo. SCE were measured for all loading cases and compared with each other to identify whether they systematically changed between loading cases and to discriminate which specimens were affected by an increase in the loading. RESULTS: The application of a compressive loading did not systematically increase the SCE. However, specimens with a large bony fragment originating from the superior and posterior aspect of the vertebral body with a centrifugal orientation had a significant increase of SCE when loaded. CONCLUSIONS: An increase in spinal internal loads resulting from a change in the patient posture may increase the SCE of burst fracture. Measurement of the SCE should take into account the bony fragment distribution of burst fracture.