Cerebrospinal fluid dynamics correlate with neurogenic claudication in lumbar spinal stenosis.

Neurogenic claudication is a typical manifestation of lumbar spinal stenosis (LSS). However, its pathophysiology is still unclear. The severity of clinical symptoms has been shown not to correlate with the degree of structural stenosis. Altered cerebrospinal fluid (CSF) flow has been suggested as one of the causative factors of LSS. The objectives of this study were to compare CSF dynamics at the lumbosacral level between patients with LSS and healthy controls and to investigate whether CSF dynamics parameters explain symptom severity in LSS. Phase-contrast magnetic resonance imaging (PC-MRI) was conducted to measure CSF dynamics in 18 healthy controls and 9 patients with LSS. Cephalic peak, caudal peak, and peak-to-peak CSF velocities were evaluated at the lumbosacral level in the patients and controls. The power of CSF dynamics parameters to predict symptom severity was determined using a linear regression analysis adjusted for demographic and structural variables. Significantly attenuated CSF flow velocity was observed in the patients compared with the controls. The cephalic peak, caudal peak, and peak-to-peak velocities at the lumbar level were greater in the controls than in the patients (p<0.001). The predictive power increased most when the peak-to-peak velocity was added (adjusted R2 = 0.410) to the model with age, body mass index, and the minimum anterior-posterior diameter (adjusted R2 = 0.306), and the peak-to-peak velocity was the only statistically significant variable. CSF dynamics variables showed an association with the severity of LSS symptoms, independent of structural stenosis. PC-MRI can help to further our understanding of the pathophysiology of neurogenic claudication and support the diagnosis of LSS.

MicroRNA expression in the cerebrospinal fluid of dogs with and without cervical spondylomyelopathy.

BACKGROUND: Osseous-associated cervical spondylomyelopathy (OA-CSM) is a common condition of the cervical vertebral column that affects giant dog breeds. MicroRNAs (miRNAs) are small RNAs that regulate gene expression, and recent data suggest that circulating miRNAs present in biological fluids may serve as potential biomarkers for disease. The miRNA profiles of cerebrospinal fluid (CSF) from healthy dogs and dogs clinically affected by OA-CSM have not been described. OBJECTIVE: To characterize the expression levels of miRNAs present in the CSF of normal Great Danes and identify differentially expressed miRNAs in the CSF of Great Danes clinically affected with OA-CSM. ANIMALS: Client-owned dogs: 12 control, 12 OA-CSM affected. METHODS: Cerebrospinal fluid samples were collected prospectively. MicroRNA expression was evaluated using the NanoString nCounter platform and quantitative real-time PCR. RESULTS: We identified 8 miRNAs with significant differential expression. MiR-299-5p and miR-765 had increased expression levels in the CSF of OA-CSM-affected dogs, whereas miR-494, miR-612, miR-302-d, miR-4531, miR-4455, and miR-6721-5p had decreased expression levels in OA-CSM affected dogs compared to clinically normal dogs. Quantitative real-time PCR was performed to validate the expression levels of 2 miRNAs (miR-494 and miR-612), and we found a 1.5-fold increase in miR-494 expression and a 1.2-fold decrease in miR-612 in the CSF of the OA-CSM affected group (P = .41 and .89, respectively). CONCLUSIONS AND CLINICAL IMPORTANCE: Data generated from our study represent an initial characterization of the miRNA profile of normal canine CSF and suggest that a distinct CSF miRNA expression profile is associated with OA-CSM.

Lysophosphatidic acids and their substrate lysophospholipids in cerebrospinal fluid as objective biomarkers for evaluating the severity of lumbar spinal stenosis.

Lysophospholipids (LPLs) are known to have potentially important roles in the initiation and maintenance of neuropathic pain in animal models. This study investigated the association between the clinical severity of lumbar spinal stenosis (LSS) and the cerebrospinal fluid (CSF) levels of LPLs, using human samples. We prospectively identified twenty-eight patients with LSS and fifteen controls with idiopathic scoliosis or bladder cancer without neurological symptoms. We quantified LPLs from CSF using liquid chromatography-tandem mass spectrometry. We assessed clinical outcome measures of LSS (Neuropathic Pain Symptom Inventory (NPSI) and Zurich Claudication Questionnaire (ZCQ)) and categorized patients into two groups according to their severity. Five species of lysophosphatidic acid (LPA), nine species of lysophosphatidylcholine (LPC), and one species of lysophosphatidylinositol (LPI) were detected. The CSF levels of all species of LPLs were significantly higher in LSS patients than controls. Patients in the severe NPSI group had significantly higher LPL levels (three species of LPA and nine species of LPC) than the mild group. Patients in the severe ZCQ group also had significantly higher LPL levels (four species of LPA and nine species of LPC). This investigation demonstrates a positive correlation between the CSF levels of LPLs and the clinical severity of LSS. LPLs are potential biomarkers for evaluating the severity of LSS.

Froin Syndrome After Spinal Cord Injury.

BACKGROUND: Froin syndrome is characterized by xanthochromia and hypercoagulability of the cerebrospinal fluid (CSF) due to elevated protein levels. This entity results from blockage of the spinal canal by a mass lesion leading to an isolated caudal CSF space. CASE DESCRIPTION: A 48-year-old male, who developed spasticity after a C6 spinal cord injury (SCI) 20 years earlier, presented with subobstruction of his intrathecal baclofen pump. A catheter access port aspiration revealed an extremely high protein concentration (38 g/L) with no signs of infection. Froin syndrome was confirmed when magnetic resonance imaging showed a complete obstruction of the spinal canal at the SCI level. CONCLUSIONS: We report the first case of Froin syndrome after SCI. Froin syndrome can impact intrathecal drug delivery and CSF diagnostics.

Correlation between lumbar spinal stenosis based on morphology of the dural sac and the quality of life / Correlação entre estenose lombar baseada na morfologia do saco dural e qualidade de vida / Correlación entre estenosis lumbar basada en la morfología del saco dural y la calidad de vida

ABSTRACT Objective: To evaluate the possible existence of a significant correlation between quality of life and severity classification of lumbar stenosis based on dural sac morphology in outpatients. Methods: Forty patients with a diagnosis of lumbar stenosis followed at a university hospital were submitted to magnetic resonance imaging (MRI) and quality of life questionnaires: Oswestry Disability Index (ODI), SF-36, Swiss Spinal Stenosis Questionnaire (SSS) and EQ-5D. They were classified as type A, B, C or D based on MRI. For the statistical analysis, the Spearman correlation was used. Results: Seventeen female patients and 23 male patients with mean age of 56.5 years constituted the sample. ODI had a mean dysfunction of 44.9%, the PCS score averaged 29.9, the MCS score was 41.3. The general symptoms of SSS presented a mean of 3.2 and the EQ-5D presented an average of 0.491. The patients with the highest severity in the classification were not necessarily those who presented worse scores in the quality of life questionnaires. Conclusion: The classification of severity of the lumbar spinal stenosis based on dural sac morphology does not correlate with the applied quality of life questionnaires. Level of Evidence III; Cross-sectional observational study.

RESUMO Objetivo: Avaliar a possível existência de uma correlação significativa entre a classificação de gravidade da estenose lombar baseada na morfologia do saco dural e a qualidade de vida em pacientes ambulatoriais. Método: Quarenta pacientes com diagnóstico de estenose lombar, acompanhados em um hospital universitário, foram submetidos ao exame de Ressonância Magnética (RM) e a questionários de qualidade de vida: Oswestry Disability Index (ODI), SF-36, Swiss Spinal Stenosis Questionnaire (SSS) e EQ-5D. Foram classificados em tipo A, B, C ou D, baseados na RM. Na análise estatística, foi realizada a correlação de Spearman. Resultados: 17 pacientes do sexo feminino e 23 do sexo masculino com média de idade de 56,5 anos. ODI apresentou uma disfunção média de 44,9%, o PCS escore médio de 29,9, o MCS de 41,3. Os Sintomas gerais do SSS apresentaram média de 3,2 e o EQ-5D apresentou média de 0,491. Os pacientes com maior gravidade da classificação não foram, necessariamente, os que apresentaram piores escores nos questionários de qualidade de vida. Conclusão: Classificação de estenose lombar baseada na morfologia do saco dural não apresenta correlação com os questionários de qualidade de vida aplicados. Nível de Evidência III; Estudo observacional analítico transversal.

RESUMEN Objetivo: Evaluar la posible existencia de una correlación significativa entre la calidad de vida y la clasificación de la gravedad de la estenosis lumbar basada en la morfología del saco dural en pacientes ambulatorios. Métodos: Cuarenta pacientes con diagnóstico de estenosis lumbar seguidos en un hospital universitario fueron sometidos a resonancia magnética (RM) y a cuestionarios de calidad de vida: Índice de Discapacidad de Oswestry (ODI), SF-36, Swiss Spinal Stenosis Questionnaire (SSS) y EQ-5D. Se clasificaron como tipo A, B, C o D según la resonancia magnética. Para el análisis estadístico, se utilizó la correlación de Spearman. Resultados: Diecisiete pacientes del sexo femenino y 23 del sexo masculino con una edad promedio de 56,5 años constituyeron la muestra. El ODI tuvo una disfunción promedio de 44,9%, la puntuación PCS fue en media 29,9, la puntuación MCS fue de 41,3. Los síntomas generales de SSS presentaron una media de 3,2 y el EQ-5D presentó una media de 0,491. Los pacientes con mayor gravedad en la clasificación no fueron necesariamente los que presentaron puntuaciones peores en los cuestionarios de calidad de vida. Conclusión: La clasificación de la gravedad de la estenosis lumbar basada en la morfología del saco dural no se correlaciona a los cuestionarios de calidad de vida aplicados. Nivel de evidencia III; Estudio observacional analítico transversal.

Aspiration of sterile post-operative spinal fluid collections using low-dose computed tomography guidance.

Sterile postoperative seromas can develop after posterior spinal surgery and cause pain, weakness, and numbness. Management typically involves operative evacuation. We propose that these collections can be managed with percutaneous computed tomography (CT) guided aspiration, potentially saving the patient an additional surgery. Here, we evaluate the safety and efficacy of this approach. Patients who developed symptomatic postoperative seromas within 60 days following surgery for spinal canal stenosis and had stable neurologic exams were considered for CT-guided percutaneous aspiration. To be considered for this approach, patients had to have pre-procedural evidence of radiographic spinal cord or cauda equina compression, hemodynamic stability, and low suspicion for infection. A total of 16 symptomatic collections were aspirated among 15 patients. The mean volume of fluid removed was 32.0 mL. There were no peri- or post-procedural complications. Eight (50%) had resolution or substantial improvement of their symptoms (p = 0.0002 when compared to the null hypothesis). One patient had short interval improvement but return of their initial symptoms 12 h following aspiration, 3/16 (19%) had minimal improvement, and 4/16 (25%) had no change in symptoms. Fluid collections that appeared denser on the pre-procedural CT were associated with retrieval of more sanguineous appearing fluid (p = 0.08). Neither the amount nor quality of fluid aspirated was associated with outcome. We conclude that percutaneous CT-guided aspiration of postoperative seromas is safe and should be considered as an alternative to open surgical evacuation in patients with stable neurologic exams.

Immediate improvement of intraoperative monitoring signals following CSF release for cervical spine stenosis: Case report.

Cervical spondylotic myelopathy (CSM) is a degenerative pathology characterized by partial or complete conduction block on intraoperative neuromonitoring. We describe a case treated using osseoligamentous decompression and durotomy for cerebrospinal fluid (CSF) release. Intraoperative monitoring demonstrated immediate signal improvement with CSF release, suggesting that clinical improvement in CSM may result from resolution of CSF flow anomalies.

Elevated levels of phosphorylated neurofilament heavy subunit in the cerebrospinal fluid of patients with lumbar spinal stenosis: preliminary findings.

BACKGROUND CONTEXT: The phosphorylated neurofilament heavy subunit (pNfH) is an axon fiber structural protein that is released into the cerebrospinal fluid (CSF) after nerve damage. Although the previous studies have reported elevated CSF levels of pNfH in various neurological diseases, including amyotrophic lateral sclerosis, these levels have not been examined in patients with spinal stenosis. PURPOSE: The purpose of this study was to investigate the CSF levels of pNfH in patients with lumbar spinal stenosis (LSS) and to examine the relationship between CSF levels of pNfH and the severity of LSS. STUDY DESIGN: This is a prospective observational study. PATIENT SAMPLE: We included consecutive patients with LSS who were undergoing myelography for preoperative evaluation. The CSF samples from patients with idiopathic scoliosis were used as the controls. OUTCOME MEASURES: Physiological measures: CSF levels of pNfH were measured using an enzyme-linked immunosorbent assay. The Zurich Claudication Questionnaire (ZCQ) and the Numerical Rating Scale (NRS) for sciatic pain were used to assess the clinical severity of LSS, and patients were grouped into tertiles according to their symptom severity and pain grading. Axial magnetic resonance imaging was used to evaluate the morphological severity of LSS, and patients were classified into three groups based on their morphological grading (using the CSF/rootlet ratio). METHODS: Analysis of variance was used to examine the relationship between the CSF levels of pNfH and the severity of LSS. RESULTS: Thirty-three patients with LSS were included (13 men and 20 women and mean age 73.2 [range 58-88] years). Most patients (n=32) were positive for pNfH in their CSF (mean 1,344 [149-9,250] pg/mL), whereas all control subjects were negative for pNfH in their CSF. Regarding the association with clinical severity, patients in the third tertiles of ZCQ and NRS tended to have higher levels of pNfH compared with the other groups. There was no association between the CSF level of pNfH and the morphological severity of LSS. CONCLUSIONS: This study detected elevated pNfH levels in the CSF of patients with LSS. Patients with severe clinical symptoms were more likely to exhibit high levels of pNfH. Our results indicate the potential usefulness of pNfH as a biomarker for compressive spinal disorders.

Proinflammatory cytokines in the cerebrospinal fluid of patients with lumbar radiculopathy.

In pathologic radicular pain of lumbar spinal stenosis, cytokines such as tumor necrosis factor-alpha (TNF-α) and interleukins (ILs) play a crucial role in the pathogenesis of nerve degeneration and pain. We investigated TNF-α and IL-6 levels in the cerebrospinal fluid (CSF) of patients with radicular pain caused by lumbar spinal stenosis (LSS). A total of 30 LSS patients and 10 age-matched controls were examined. CSF samples were obtained adjacent to the level of stenosis in 30 LSS patients, and at the L4-L5 level in the 10 control patients. TNF-α and IL-6 levels in the samples were analyzed using enzyme-linked immunosorbent assays (ELISA). We compared the amounts of TNF-α and IL-6 with severity of pain (low back and leg pain), walking ability, and severity of stenosis (cross-sectional area of dural space). The concentration of IL-6 was significantly higher in LSS patients than in controls, but TNF-α levels were beneath the limit of detection. There was no correlation between IL-6 levels and severity of pain or walking ability (p > 0.05). However, there was a significant correlation between IL-6 levels and severity of stenosis (p < 0.05). The current study showed that the increased CSF IL-6 levels in LSS patients with radicular pain were not correlated with pain severity; although not proven in this study, the increase in CSF IL-6 concentration could indicate pathological nerve damage or degeneration of lumbar radiculopathy represented by the severity of stenosis.

Clinical significance of cerebrospinal fluid nitric oxide concentrations in degenerative cervical and lumbar diseases.

In animal models of degenerative lumbar disease, inducible nitric oxide synthase (iNOS) is expressed in macrophages and Schwann cells following compression of the cauda equina. We previously reported that NO metabolites (nitrite plus nitrate: [NOx]) in the cerebrospinal fluid (CSF) correlate with postoperative pain relief in patients with degenerative lumbar disease and with neurologic recovery rate postoperatively or after conservative treatment in patients with spinal cord injury. The objective of the present study was to examine the relationship between [NOx] and neurologic severity, and recovery in degenerative cervical and lumbar diseases. Two hundred fifty-seven cases, including 85 patients with cervical compression myelopathy (CCM), 25 with cervical disc herniation (CDH), 70 with lumbar canal stenosis (LCS), and 77 with lumbar disc herniation (LDH), were examined. The CSF [NOx] was measured using the Griess method. Severity of neurologic impairment and clinical recovery was assessed using the Japanese Orthopedic Association score and Hirabayashi's method. [NOx] in CCM and LCS, but not CDH and LDH groups, was significantly higher than that in controls, and correlated with postoperative recovery rates, but not with preoperative neurologic severity. [NOx] significantly correlated with neurologic recovery following surgery for CCM and LCS.

Spinal subarachnoid space pressure measurements in an in vitro spinal stenosis model: implications on syringomyelia theories.

Full explanation for the pathogenesis of syringomyelia (SM), a neuropathology characterized by the formation of a cystic cavity (syrinx) in the spinal cord (SC), has not yet been provided. It has been hypothesized that abnormal cerebrospinal fluid (CSF) pressure, caused by subarachnoid space (SAS) flow blockage (stenosis), is an underlying cause of syrinx formation and subsequent pain in the patient. However, paucity in detailed in vivo pressure data has made theoretical explanations for the syrinx difficult to reconcile. In order to understand the complex pressure environment, four simplified in vitro models were constructed to have anatomical similarities with post-traumatic SM and Chiari malformation related SM. Experimental geometry and properties were based on in vivo data and incorporated pertinent elements such as a realistic CSF flow waveform, spinal stenosis, syrinx, flexible SC, and flexible spinal column. The presence of a spinal stenosis in the SAS caused peak-to-peak cerebrospinal fluid CSF pressure fluctuations to increase rostral to the stenosis. Pressure with both stenosis and syrinx present was complex. Overall, the interaction of the syrinx and stenosis resulted in a diastolic valve mechanism and rostral tensioning of the SC. In all experiments, the blockage was shown to increase and dissociate SAS pressure, while the axial pressure distribution in the syrinx remained uniform. These results highlight the importance of the properties of the SC and spinal SAS, such as compliance and permeability, and provide data for comparison with computational models. Further research examining the influence of stenosis size and location, and the importance of tissue properties, is warranted.

Evaluation by fluid/structure-interaction spinal-cord simulation of the effects of subarachnoid-space stenosis on an adjacent syrinx.

A finite-element numerical model was constructed of the spinal cord, pia mater, filum terminale, cerebrospinal fluid in the spinal subarachnoid space (SSS), and dura mater. The cord was hollowed out by a thoracic syrinx of length 140 mm, and the SSS included a stenosis of length 30 mm opposite this syrinx. The stenosis severity was varied from 0% to 90% by area. Pressure pulse excitation was applied to the model either at the cranial end of the SSS, simulating the effect of cranial arterial pulsation, or externally to the abdominal dura mater, simulating the effect of cough. A very short pulse was used to examine wave propagation; a pulse emulating cardiac systole was used to examine the effects of fluid displacement. Additionally, repetitive sinusoidal excitation was applied cranially. Bulk fluid flow past the stenosis gave rise to prominent longitudinal pressure dissociation ("suck") in the SSS adjacent to the syrinx. However, this did not proportionally increase the longitudinal motion of fluid in the syrinx. The inertia of the fluid in the SSS, together with the compliance of this space, gave a resonance capable of being excited constructively or destructively by cardiac or coughing impulses. The main effect of mild stenosis was to lower the frequency of this resonance; severe stenosis damped out to-and-fro motions after the end of the applied excitation. Syrinx fluid motion indicated the fluid momentum and thus the pressure developed when the fluid was stopped by the end of the syrinx; however, the tearing stress in the local cord material depended also on the instantaneous local SSS pressure and was therefore not well predicted by syrinx fluid motion. Stenosis was also shown to give rise to a one-way valve effect causing raised SSS pressure caudally and slight average cord displacement cranially. The investigation showed that previous qualitative predictions of the effects of suck neglected factors that reduced the extent of the resulting syrinx fluid motion and of the cord tearing stress, which ultimately determines whether the syrinx lengthens.

The CSF creatine kinase-BB isoenzyme activity in experimental lumbar spinal stenosis model.

STUDY DESIGN: An investigation of creatine kinase (CK)-BB isoenzyme activity in cerebrospinal fluid (CSF) of the rabbits after experimentally induced spinal stenosis. OBJECTIVES: To create a lumbar spinal stenosis (LSS) model at conus medullaris level without laminectomy in rabbits and to investigate the importance of CK-BB isoenzyme activity in CSF associated with electrophysiologic and histopathologic changes in the spinal cord. SUMMARY OF BACKGROUND DATA: LSS is a disorder characterized by leg pain and difficulty of walking. Narrowing of the spinal canal and compression on the spinal cord and nerves are the main features of spinal stenosis. METHODS: Fifteen male albino rabbits were used in this study. A reproducible, subacute LSS model was created in all rabbits, and CSF CK-BB activity was measured above and below the stenosis level. The electrophysiologic evaluation and the histopathologic examination of the conus medullaris were also performed in each rabbit. RESULTS: The CK-BB activity was 71.5% in CSF samples that were obtained below the stenosis. The activity was 44.5% in samples obtained above the stenosis and 43.6% in nonstenotic rabbits. In the electrophysiologic studies, the mean amplitudes were decreased and the latency values were lengthened in all ascending and descending nerve potentials at both sides of the stenosis. The number of the neural cells was decreased and imperception of the nucleolus of neural cells and vacuolar degeneration were observed in the histopathologic examination of conus medullaris. CONCLUSIONS: The activity of CK-BB isoenzyme was increased in CSF of which the circulation was disturbed as a result of neural ischemia, which was accepted in the pathophysiology of LSS.

Spinal contribution to CSF pressure lowering effect of mannitol in cats.

OBJECTIVES: After application of hyperosmolar mannitol the cerebrospinal (CSF) pressure is usually lowered within 30 min but this effect cannot be explained either by changes in intracranial blood volume and flow or by changes in brain volume. We assume that this effect of mannitol my be consequence of CSF volume decrease primarily in the spinal CSF due to high compliance of the spinal dura. METHODS: To explore such a possibility we planned to separate spinal and cerebral CSF. In chloralose anaesthetized cats dorsal laminectomy of C2 vertebrae was performed and a plastic semi ring was positioned extradurally separating cranial and spinal CSF. CSF pressures were recorded via cannulas positioned in lateral ventricle and lumbar subarachnoid space at L3 vertebrae, respectively. RESULTS: After intravenous bolus of 20% mannitol (0.5 or 1.0 g/kg/ 3 min) in control animals without cervical stenosis, the fall of both ventricular and lumbar CSF pressures was equal over time. At 15 min after mannitol application in cats with cervical stenosis an slight increase of ventricular and a fall of lumbar CSF pressures were observed, while at 30 min a gradient of these pressures of 5.5 and 7 cm H2O at lower and higher dose of mannitol, respectively, were registered. However, after removal of cervical stenosis these gradients disappeared. CONCLUSION: The observed changes of CSF pressures in spinal and intracranial space indicate that spinal subarachnoid space contributes a great deal to overall fall of CSF pressure and volume in the early period after mannitol application probably due to high compliance of the spinal dura.

Metabolic changes in the cerebrospinal fluid of patients with lumbar disc herniation or spinal stenosis.

Metabolite levels in cerebrospinal fluid from patients with lower back pain and/or sciatica caused by disc herniation or spinal stenosis were compared with levels in pain-free controls using proton magnetic resonance spectroscopy. Significant differences for several metabolites were found in patients with pain compared with controls. Most changes were found in the group with disc herniation, including reductions in glucose, alanine, and lactate, suggesting increased aerobic metabolism in this group. There was a significant reduction in the level of glucose in the group with spinal stenosis irrespective of whether the patients were compared with the whole control group (age-weighted) or with age-matched controls. Additionally, inositol and creatinine were reduced in patients with disc herniation. Inositol was also significantly reduced in the spinal stenosis group when age matched to controls. Insofar as the levels of pain recorded by the patients with lumbar pathology were similar in the two groups, it seems more likely that the reductions in metabolite levels recorded in the group with disc herniations are related to disc pathology rather than the perception of pain. However, the possibility that pain perception contributes to the metabolic changes cannot be excluded.

[Measurement of CSF flow in the spinal canal using MRI with an optimized MRI protocol: experimental and clinical studies]. / MR-tomographische Liquorflussmessungen am Spinalkanal mit einem optimierten MRT-Protokoll: Experimentelle und klinische Untersuchungen.

PURPOSE: Measurement of the oscillating CSF flow in the spinal canal (SC) of healthy volunteers and in patients with post-traumatic syringomyelia (PTS) using an optimized MRI protocol as well as to determine whether stenosis induced velocity changes are detectable using MRI. METHODS: In 68 healthy volunteers quantitative studies of CSF flow in the cervical, thoracic, and lumbar regions were performed. First, an optimized sequence was developed and tested in 19 volunteers using four different flow-encoding velocities (4, 8, 12, 16 cm/s). Secondly, the optimized sequence was employed in 49 volunteers to measure the different CSF patterns in the cervical, thoracic, and lumbar spinal canals (CSC, TSC, LSC). Part three of the study, in which patients with PTS are being examined is still underway. We measured the maximum velocity (cm/s), the pixel area (mm2), and the stroke volume (ml/s). Using a flow model the velocities prior to and after compression with 5 different power levels were measured at the stenosis and at a distance of 70 cm. RESULTS: A total of 226 dynamic measurements have been performed--so far 76 in the first part (62 = 81.5% evaluable) and 150 in the second part--using the optimized sequence and optimal flow velocities. A flow-encoding sequence of 12 cm/s was found best in the CSC and one of 6 cm/s in the TSC and LSC. The maximum velocity in the CSC was 0.95 cm/s with the flow being directed caudal and 0.38 cm/s with the flow being directed cranial. In the TSC the values were 4.7 cm/s and 1.65 cm/s and in the LSC 0.96 cm/s and 0.59 cm/s. The highest velocities were found at the TSC, which has the smallest diameter compared to the CSC and LSC. In the 4 patients with PTS, the maximum velocities were between 0.09 cm/s and 0.97 cm/s with the flow being directed cranial and between 0.04 cm/s and 1.03 cm/s with the flow being directed caudal. The stroke volumina in the CSC were between 0.1 and 1.23 ml/s (mean: 0.48 ml/s) and 0.2 and 2.45 ml/s (mean: 0.66 ml/s) in the TSC and in the LSC 0.08 ml/s and 0.67 ml/s (mean: 0.29 ml/s). The results of the flow model studies showed an increase of velocity between 2.06 and 4.94 cm/s (mean: 3.31 cm/s) at the stenosis and 1.1 and 1.33 cm/s (mean: 1.23 cm/s) at a distance of 70 cm. CONCLUSION: Quantitative measurement of the oscillating CSF flow in the entire spinal canal (SC) is possible using an optimized MRI protocol as well as to detect stenosis induced velocity changes. Due to the high interindividual variability in the data of spinal CSF dynamics, further studies are necessary to collect normal data. The detection of movement of CSF in a post-traumatic spinal cord lesion may alter the therapeutic management.

Diffusion tensor MRI of the spinal cord.

Apparent diffusion tensor (ADT) measurements on the spinal cord using a pulsed-field-gradient (PFG) multi-shot echo-planar imaging (EPI) sequence are presented. In a study of 10 healthy volunteers, the obtained rotationally invariant anisotropy information is compared to the results obtained by the rotationally dependent methods. The water diffusivity in the direction parallel to the fibers was found to be almost 2.5 times higher than the average diffusivity in directions perpendicular to the fibers and showed cylindrically symmetric anisotropy characteristics. The influence of partial volume effects and the point spread function on the measured results was evaluated, and it was the concluded that a resolution of 1 mm in the read and phase directions is required to obtain unbiased values. Possible clinical implications were demonstrated by investigating the diffusion characteristics of 10 patients suffering from narrowing of the cervical canal. The changes in the diffusion characteristics were found to be large enough to allow a robust detection of diffusion changes in the spine, even in cases in which conventional T(2) and T(1) weighted images were unable to detect any lesion.

Application of spatial modulation of magnetization to cervical spinal stenosis for evaluation of the hydrodynamic changes occurring in cerebrospinal fluid.

OBJECTIVE: To evaluate the hydrodynamic changes occurring in cerebrospinal fluid (CSF) flow in cervical spinal stenosis using the spatial modulation of magnetization (SPAMM) technique. MATERIALS AND METHODS: Using the SPAMM technique, 44 patients with cervical spinal stenosis and ten healthy volunteers were investigated. The degree of cervical spinal stenosis was rated as low-, intermediate-, or high-grade. Lowgrade stenosis was defined as involving no effacement of the subarachnoid space, intermediate-grade as involving effacement of this space, and high-grade as involving effacement of this space, together with compressive myelopathy. The patterns of SPAMM stripes and CSF velocity were evaluated and compared between each type of spinal stenosis and normal spine. RESULTS: Low-grade stenosis (n = 23) revealed displacement or discontinuity of stripes, while intermediate- (n = 10) and high-grade (n = 11) showed a continuous straight band at the stenotic segment. Among low-grade cases, 12 showed wave separation during the systolic phase. Peak systolic CSF velocity at C4-5 level in these cases was lower than in volunteers (p <.05), but jet-like CSF propulsion was maintained. Among intermediate-grade cases, peak systolic velocity at C1-2 level was lower than in the volunteer group, but the difference was not significant (p >.05). In high-grade stenosis, both diastolic and systolic velocities were significantly lower (p <.05). CONCLUSION: Various hydrodynamic changes occurring in CSF flow in cervical spinal stenosis were demonstrated by the SPAMM technique, and this may be a useful method for evaluating CSF hydrodynamic change in cervical spinal stenosis.

Application of Spatial Modulation of Magnetization to Cervical Spinal Stenosis for Evaluation of the Hydrodynamic Changes Occurring in Cerebrospinal Fluid

OBJECTIVE: To evaluate the hydrodynamic changes occurring in cerebrospinal fluid (CSF) flow in cervical spinal stenosis using the spatial modulation of magnetization (SPAMM) technique. MATERIALS AND METHODS: Using the SPAMM technique, 44 patients with cervical spinal stenosis and ten healthy volunteers were investigated. The degree of cervical spinal stenosis was rated as low-, intermediate-, or high-grade. Low-grade stenosis was defined as involving no effacement of the subarachnoid space, intermediate-grade as involving effacement of this space, and high-grade as involving effacement of this space, together with compressive myelopathy. The patterns of SPAMM stripes and CSF velocity were evaluated and compared between each type of spinal stenosis and normal spine. RESULTS: Low-grade stenosis (n = 23) revealed displacement or discontinuity of stripes, while intermediate- (n = 10) and high-grade (n = 11) showed a continuous straight band at the stenotic segment. Among low-grade cases, 12 showed wave separation during the systolic phase. Peak systolic CSF velocity at C4 -5 level in these cases was lower than in volunteers (p .05). In high-grade stenosis, both diastolic and systolic velocities were significantly lower (p <.05). CONCLUSION: Various hydrodynamic changes occurring in CSF flow in cervical spinal stenosis were demonstrated by the SPAMM technique, and this may be a useful method for evaluating CSF hydrodynamic change in cervical spinal stenosis.

MR imaging of cerebrospinal fluid flow and spinal cord motion in neurologic disorders of the spine.

In summary, MR imaging of CSF and cord motion helps to evaluate diseases affecting cord and CSF motion and to identify the specific pathophysiology involved. A number of significant points have been made. First, MR imaging flow studies can be useful in evaluating CSF spaces and cystic diseases. Second, longitudinal and transverse motions occur in the spinal cord and CSF. Traveling wave motion occurs along the length of the spinal cord. Third, spinal cord tethering is associated with decreased cord velocity and loss of cord displacement at tethering site. Decreased transverse velocities occur with lateral cord tethering to the spinal canal. Fourth, in spinal dysraphism, longitudinal cord velocity is decreased by tethering, and is normal in asymptomatic patients with low conus. Normal cord motion helps to rule out possible tethering in symptomatic dysraphism with hydromyelia. Fifth, in acquired and nonmyelodysplastic symptomatic tethering, spinal cord motion is decreased. Sixth, in symptomatic cord compression, CSF flow and cord motion decrease, but recover after surgical decompression and after compensatory atrophy. Seventh, in asymptomatic spinal stenosis, cord motion is normal or increased. Diffuse spinal stenosis with cord atrophy leads to diffuse cord acceleration and prolonged cord caudal velocity, possibly related to the loss of the transverse mobility of the cord. Finally, focal spinal stenosis leads to focal dynamic cord deformation and can be associated with prominent intramedullary deformations. When compression is severe or symptomatic, cord motion is significantly decreased. Postoperative cases demonstrate good recovery of cord and CSF motion, unless compression or obstruction is still present.