The Mechanism of Volume Regulation by Cervical Neuroforaminal Veins as was Previously Demonstrated for the Internal Vertebral Venous Plexus (IVVP) in the Cervical and Lumbar Region

SUMMARY: Head and cervical spine movements cause narrowing or widening of neuroforamina. In healthy individuals these movements do not cause symptoms of radiculopathy. This implies a compensating volume-regulating mechanism of the neuroforamina. Such a mechanism has been postulated in the years before CT and MRI for the neuroforaminal veins. Dural sac indentations with emptying and refilling of the internal vertebral venous plexus (IVVP) were postulated in the lumbar region using myelography. Emptying of the IVVP occurs in the lumbar spine when moving towards maximal extension and refilling while moving towards maximal flexion. Such indentations have not been shown in the cervical region. With MRI this mechanism has been demonstrated during axial rotation in the C1-C2 segment. It consists of emptying and refilling of the IVVP and thus prevents dural sac compression. During spinal surgery, the IVVP and connecting neuroforaminal veins may be damaged. Because the clinical implications of dysfunction of this protecting mechanism of the IVVP and its neuroforaminal venous connections are not clear, the consequences of such damage are unknown. Therefore, these venous structures should be examined by studying the cervical spine in supine position and, if possible, in different postures (flexion, extension and axial rotation) using MRI with contrast-enhancement and fat suppression. These images may be a basis for future advancement of clinical care.

Los movimientos de la cabeza y la columna cervical provocan un estrechamiento o ensanchamiento de las neuroforaminas. En individuos sanos estos movimientos no causan síntomas de radiculopatía. Esto implica un mecanismo compensador de regulación del volumen de las neuroforaminas. Este mecanismo se ha postulado en los años anteriores a la TC y la RM para las venas neuroforaminales. Mediante mielografía se postularon hendiduras del saco dural con vaciado y llenado del plexo venoso vertebral interno (PVVI) en la región lumbar. El vaciado del PVVI se produce en la columna lumbar cuando se mueve hacia la máxima extensión y se rellena mientras se mueve hacia la máxima flexión. En la región cervical no se han observado tales depresiones. Con resonancia magnética se ha demostrado este mecanismo durante la rotación axial en el segmento C1-C2. Consiste en vaciar y rellenar la PVVI y así evitar la compresión del saco dural. Durante la cirugía de columna, la PVVI y las venas neuroforaminales que las conectan pueden dañarse. Debido a que las implicaciones clínicas de la disfunción de este mecanismo protector de la PVVI y sus conexiones venosas neuroforaminales no están claras, se desconocen las consecuencias de dicho daño. Por tanto, estas estructuras venosas deben examinarse estudiando la columna cervical en decúbito supino y, si es posible, en diferentes posturas (flexión, extensión y rotación axial) mediante resonancia magnética con contraste y supresión grasa. Estas imágenes pueden ser una base para futuros avances de la atención clínica.

Predictive Factors for Successful Outcome of Pulsed Radiofrequency Treatment in Patients with Intractable Lumbosacral Radicular Pain.

BACKGROUND: In a previous prospective study on pulsed radiofrequency (PRF) treatment adjacent to the lumbar dorsal root ganglion (DRG) for patients with chronic lumbosacral radicular pain, we reported success in 55.4% of the patients at 6 months. Identification of predictors for success after PRF may improve outcome. We assessed the predictors of PRF in patients with chronic intractable lumbosacral radicular pain. METHODS: Patients with monosegmental chronic lumbosacral radicular pain of L5 or S1 first received a selective nerve root block at the corresponding level. Independent of the result of this block a PRF treatment at the same level was performed. At 6 weeks, 3 months, and 6 months after the procedure the outcome was evaluated. RESULTS: A positive diagnostic nerve root block and age ≥ 55 were predictive factors for successful outcome at 6 months, while disability was a negative predictor.The use of failed back surgery syndrome, gender, duration of pain, Numerical Rating Scale, level and side of treatment, DN4, and RAND-36 as predictors for success was not supported. CONCLUSIONS: Successful outcome after PRF adjacent to the DRG, in patients with intractable chronic lumbosacral radicular pain, is more likely in patients ≥ 55 years, with limited disability and after a positive diagnostic nerve root block. A combination of all these factors creates a fair predictive value (AUC: 0.73).

Diagnostic Accuracy of Lumbosacral Spine Magnetic Resonance Image Reading by Chiropractors, Chiropractic Radiologists, and Medical Radiologists.

STUDY DESIGN: A cross-sectional diagnostic accuracy study was conducted in 2 sessions. OBJECTIVE: It is important to know whether it is possible to accurately detect "specific findings" on lumbosacral magnetic resonance (MR) images and whether the results of different observers are comparable. SUMMARY OF BACKGROUND DATA: Health care providers frequently use magnetic resonance imaging in the diagnostic process of patients with low back pain. The use of MR scans is increasing. This leads to an increase in costs and to an increase in risk of inaccurately labeling patients with an anatomical diagnosis that might not be the actual cause of symptoms. METHODS: A set of 300 blinded MR images was read by medical radiologists, chiropractors, and chiropractic radiologists in 2 sessions. Each assessor read 100 scans in round 1 and 50 scans in round 2. The reference test was an expert panel.For all analyses, the magnetic resonance imaging findings were dichotomized into "specific findings" or "no specific findings." For the agreement, percentage agreement and κ values were calculated and for validity, sensitivity, and specificity. Sensitivity analysis was done for classifications A and B (prevalence of 31% and 57%, respectively). RESULTS: The intraobserver κ values for chiropractors, chiropractic radiologists, and medical radiologists were 0.46, 0.49, and 0.69 for A and 0.55, 0.75, and 0.64 for B, respectively.The interobserver κ values were lowest for chiropractors (0.28 for A, 0.37 for B) and highest for chiropractic radiologists (0.50 for A, 0.49 for B).The sensitivities of the medical radiologists, chiropractors, and chiropractic radiologists were 0.62, 0.71, and 0.75 for A and 0.70, 0.74, 0.84 for B, respectively.The specificities of medical radiologists, chiropractic radiologists, and chiropractors were 0.82, 0.77, and 0.70 for A and 0.74, 0.52, and 0.61 for B, respectively. CONCLUSION: Agreement and validity of MR image readings of chiropractors and chiropractic and medical radiologists is modest at best. This study supports recommendations in clinical guidelines against routine use of magnetic resonance imaging in patients with low back pain. LEVEL OF EVIDENCE: 3.

Cost-effectiveness of CTA, MRA and DSA in patients with non-traumatic subarachnoid haemorrhage.

OBJECTIVES: Intra-arterial digital subtraction angiography (DSA), magnetic resonance angiography (MRA) and computed tomographic angiography (CTA) are imaging modalities used for diagnostic work-up of non-traumatic subarachnoid haemorrhage. The aim of our study was to compare the cost-effectiveness of MRA, DSA and CTA in the first year after the bleed. METHODS: A decision model was used to calculate costs and benefits (in quality-adjusted life-years [QALYs]) that accrued to cohorts of 1,000 patients. Costs and characteristics of diagnostic tests, therapy, patients' quality of life and associated costs were respected. The diagnostic strategy with highest QALYs and lowest costs was considered most cost-effective. RESULTS: DSA was the most effective diagnostic option, yielding on average 0.6039 QALYs (95 % CI, 0.5761-0.6327) per patient, followed by CTA 0.5983 QALYs (95 % CI, 0.5704-0.6278) and MRA 0.5947 QALYs (95 % CI, 0.5674-0.6237). Cost was lowest for DSA (39,808 ; 95 % CI, 37,182-42,663), followed by CTA (40,748 ; 95 % CI, 37,937-43,831) and MRA (41,814 ; 95 % CI, 38,730-45,146). A strategy of CTA followed by DSA if CTA was negative or coiling deemed not feasible, was as effective as DSA alone at average costs of 39,767 (95 % CI, 36,903-42,402). CONCLUSION: A combined strategy of CTA and DSA was found to be the most cost-effective diagnostic approach. MAIN MESSAGES: • We defined a standard model for cost-effectiveness analysis in diagnostic imaging. • Comparing total 1-year health costs and benefits, CTA is superior to MRA. • A strategy of combining CTA and DSA was found to be the most cost-effective diagnostic approach.

Response of asymptomatic brain metastases from small-cell lung cancer to systemic first-line chemotherapy.

PURPOSE: The purpose of this study was to investigate the radiologic response of asymptomatic brain metastases (BM) from small-cell lung cancer (SCLC) to first-line systemic chemotherapy. PATIENTS AND METHODS: From 1990 to 2003, 181 consecutive patients with SCLC were enrolled onto this study. Patients were examined by a neurologist on a regular basis. Magnetic resonance imaging (MRI) of the brain was performed routinely before (at diagnosis of SCLC) and after first-line systemic chemotherapy. Patients were treated with combination chemotherapy consisting of cyclophosphamide, doxorubicin, and etoposide. Clinically manifest BM were treated with whole-brain radiotherapy (WBRT). The response rate (RR) of BM was assessed by changes in the size or the number of enhanced lesions on MRI using standard criteria. RESULTS: Synchronous asymptomatic BM were found in 24 SCLC patients (13%). In six (27%) of the 22 assessable patients, the asymptomatic BM responded to systemic chemotherapy. A systemic response was found in 16 patients (73%). All patients became symptomatic during follow-up. The symptom-free survival did not differ between cranial responders and cranial nonresponders. CONCLUSION: The RR of asymptomatic BM from SCLC to systemic chemotherapy is 27% and evidently lower than the systemic RR. Future studies should focus on the possible beneficial effect of WBRT for patients with asymptomatic synchronous BM.

Lateralized anterior mesiotemporal lobe activation: semirandom functional MR imaging encoding paradigm in patients with temporal lobe epilepsy--initial experience.

PURPOSE: To prospectively demonstrate anterior mesiotemporal lobe (MTL) activation in healthy volunteers by using a semirandom memory-encoding paradigm and to prospectively compare lateralized functional magnetic resonance (MR) imaging activation with intracarotid amobarbital procedure (IAP) memory test results in patients with temporal lobe epilepsy (TLE) who were scheduled to undergo surgery. MATERIALS AND METHODS: The study was approved by a local ethics committee, and written informed consent was obtained from all subjects. Eight healthy volunteers and 18 patients with TLE who were scheduled for surgery were included in the functional MR imaging study involving the use of a memory-encoding paradigm with variable epoch lengths. Subjects were instructed to memorize new pictures that were mixed among pictures that they had seen before. Data analysis entailed computations of the contrast between the MTL activation induced by the new pictures and the MTL activation induced by the old pictures and of the lateralization index, defined as the relative difference in the number of activated voxels between the left and right MTLs. Lateralization indexes were compared between the patients and the volunteers and statistically correlated with the patients' IAP memory test results. To study deviations from perfect correspondence between the functional MR imaging- and IAP-derived lateralization indexes, orthogonal regression analysis was applied. Proportional relations for the patients with left-sided TLE and for those with right-sided TLE were calculated separately. RESULTS: The memory paradigm consistently activated the posterior and anterior MTL structures in both the healthy volunteers and the patients. Regression analysis revealed that functional MR imaging activation was stronger than the IAP results when it was lateralized to the contralateral MTL. This analysis also revealed a significant (P < .001) correlation between the functional MR imaging results and the IAP results in the patients with right-sided TLE but not in those with left-sided TLE (P > .1). CONCLUSION: The functional MR imaging memory-encoding paradigm consistently yielded MTL activation in the volunteers and the patients with TLE, but lateralized functional MR imaging activation was in concordance with the IAP results in only those patients with right-sided TLE.

Spinal cord feeding arteries at MR angiography for thoracoscopic spinal surgery: feasibility study and implications for surgical approach.

PURPOSE: To prospectively investigate the feasibility of contrast material-enhanced magnetic resonance (MR) angiography for visualization of the spinal vasculature in patients referred for video-assisted thoracoscopic surgical treatment of a thoracic herniated disk and to prospectively assess the influence of preoperative imaging of the spinal vasculature on the choice of surgical approach. MATERIALS AND METHODS: Eight patients (three men and five women; mean age, 58 years; range, 42-83 years) with a thoracic herniated disk underwent contrast-enhanced MR angiography of the thoracoabdominal aorta and posterior branches. Imaging was performed with three-dimensional first-pass contrast-enhanced MR angiographic technique and a triple dose of gadolinium-based contrast agent. Images were analyzed by two observers in consensus to localize the Adamkiewicz artery (AKA) and its connections to the aorta and the anterior spinal artery (ASA). This information was used to determine any change in surgical approach. RESULTS: In all eight patients, the AKA, the ASA, and the connections with the aorta were identified. The AKA originated between T9 and L2 in all patients and derived from the left side of the aorta in 75% (six of eight) of the patients. In three patients in whom the AKA was observed on the left side, the surgical approach was changed to the right side to preserve spinal cord integrity. CONCLUSION: Preoperative imaging of the AKA is feasible with contrast-enhanced MR angiography. Contrast-enhanced MR angiography can be used to image the main feeding arteries of the spinal cord in patients undergoing thoracoscopic spinal surgery, and results can be used to change the side of surgical approach.

Lessons for neuropsychology from functional MRI in patients with epilepsy.

This contribution aims to review the major findings of pre- and postsurgical functional magnetic resonance imaging (fMRI) in patients with refractory epilepsy from a neuropsychological perspective. We compared the contribution of fMRI with the intracarotid amytal procedure (IAP) with respect to functional mapping of language and memory in patients with therapy-resistant epilepsy. We conclude that using comprehensive language paradigms, fMRI has been able (1) to provide estimates of the degree of language lateralization including the degree of involvement of the nondominant hemisphere, (2) to provide information on the location of its activated network during expressive and receptive language, and (3) to help delineate eloquent language regions in the vicinity of the surgical target, thus preventing postoperative complications. The contribution of the frequently observed nondominant hemisphere activation to language should be explored and its clinical relevance determined. Evidence from fMRI studies is accumulating that reorganization of cognitive and motor function favors the activation of contralateral homotopic areas, although this process is far from understood. The exact functional contribution of atypical areas of activation should be investigated critically. In the presurgical evaluation process, detailed and reliable localization of language and memory functions of the individual patient is mandatory and should be the ultimate goal in the development of comprehensive clinical fMRI protocols.

Direction of flow in posterior communicating artery on magnetic resonance angiography in patients with occipital lobe infarcts.

BACKGROUND AND PURPOSE: In some people the blood supply to the posterior cerebral artery occurs partly or even exclusively via the carotid system. This anatomic configuration may influence the risk of occipital lobe infarction. We studied the presence and direction of flow in the posterior communicating artery (PCoA) in patients with an occipital lobe infarct and in healthy controls. METHODS: Forty-seven patients with an occipital lobe infarct were studied by MR angiography, as well as 50 young healthy controls. Special attention was paid to the presence of a PCoA and, if present, to the direction of flow. RESULTS: Significantly fewer patients than controls had an exclusive blood supply to the posterior cerebral artery via the carotid system, in both the affected (4% versus 17%; 95% CI of difference, 4% to 22%) and unaffected hemispheres (5% versus 17%; 95% CI of difference, 3% to 22%). Patients also less often had a patent PCoA with anteroposterior flow than controls (affected hemisphere, 8% versus 22%; unaffected hemisphere, 12% versus 22%; 95% CI of differences, 3% to 25% and -2% to 23%, respectively). With analysis at the level of individuals, significantly more patients showed no anteroposterior flow through the PCoA in either hemisphere than controls (79% versus 42%; 95% CI of difference, 19% to 55%). CONCLUSIONS: Supply of the posterior cerebral artery by the carotid system occurs less often in patients with an occipital lobe infarct than in healthy controls. The same was true for the unaffected hemisphere of patients, which suggests that the anatomic difference represents a causal factor (fewer collateral pathways after occlusion of the posterior cerebral artery or its branches) rather than a consequence (redistribution of blood flow after occipital infarction).

No major cognitive impairment in young children with acute lymphoblastic leukemia using chemotherapy only: a prospective longitudinal study.

PURPOSE: To study, using serial neuropsychological assessment and evaluation of school achievement, persistent neuropsychological late effects in children treated for acute lymphoblastic leukemia (ALL) at a young age with chemotherapy only. PATIENTS AND METHODS: Twenty consecutive patients underwent three evaluations, including 12 psychometric measures beside IQ. The authors applied strict methodology and a prospective-longitudinal design that started at diagnosis and extended to a median follow-up of 7 years. This report focuses on the outcome of the last evaluation. Test results were compared with healthy controls and to patients with ALL treated on a previous chemotherapy-only protocol. School achievement was evaluated in patients and their siblings. RESULTS: At the last evaluation, significantly lower test scores in patients compared with controls were found for only 2 of 14 cognitive measures (1 intelligence and 1 attention measure). No great differences were seen between school achievement of patients and siblings. Compared with the previous chemotherapy protocol, a better outcome was seen in the current study group on two measures (one memory and one attention measure). CONCLUSIONS: Children surviving ALL have no major cognitive impairment after chemotherapy, including intrathecal and high-dose intravenous methotrexate. The slightly better outcome in the current group may indicate possible adverse effects of more dexamethasone treatment in the previous group.

Brain lesions in patients visiting a memory clinic with postconcussional sequelae after mild to moderate brain injury.

Postconcussional disorder after a relatively mild head injury is common. Although a partial organic etiology is presumed, little imaging evidence exists for this assumption. In this study, patients with mild to moderate brain injury (median Glasgow Coma Scale score of 14) had more parenchymal brain lesions than control subjects (P=0.02). Additionally, the authors investigated the potential of quantifying brain injury by the magnetization transfer ratio (MTR). The curve amplitude of the MTR histogram was used as a measure of normal white matter. Patients had a lower curve amplitude than control subjects (P=0.008). This study provides evidence of persistent traumatic brain alterations in patients who sustained a relatively mild traumatic brain injury.

Bilateral thalamic infarction may result from venous rather than arterial obstruction.

Two patients are presented with bilateral thalamic infarcts, in whom magnetic resonance venography (MRV) revealed venous occlusion. These cases stress the notion that bilateral thalamic infarcts may result from venous rather than arterial obstruction, which requires different evaluation and eventual treatment.