In vivo analysis of physiological 3D blood flow of cerebral veins.

OBJECTIVES: To visualize and quantify physiological blood flow of intracranial veins in vivo using time-resolved, 3D phase-contrast MRI (4D flow MRI), and to test measurement accuracy. METHODS: Fifteen healthy volunteers underwent repeated ECG-triggered 4D flow MRI (3 Tesla, 32-channel head coil). Intracranial venous blood flow was analysed using dedicated software allowing for blood flow visualization and quantification in analysis planes at the superior sagittal, straight, and transverse sinuses. MRI was evaluated for intra- and inter-observer agreement and scan-rescan reproducibility. Measurements of the transverse sinuses were compared with transcranial two-dimensional duplex ultrasound. RESULTS: Visualization of 3D blood flow within cerebral sinuses was feasible in 100 % and within at least one deep cerebral vein in 87 % of the volunteers. Blood flow velocity/volume increased along the superior sagittal sinus and was lower in the left compared to the right transverse sinus. Intra- and inter-observer reliability and reproducibility of blood flow velocity (mean difference 0.01/0.02/0.02 m/s) and volume (mean difference 0.0002/-0.0003/0.00003 l/s) were good to excellent. High/low velocities were more pronounced (8 % overestimation/9 % underestimation) in MRI compared to ultrasound. CONCLUSIONS: Four-dimensional flow MRI reliably visualizes and quantifies three-dimensional cerebral venous blood flow in vivo and is promising for studies in patients with sinus thrombosis and related diseases. KEY POINTS: • 4D flow MRI can be used to visualize and quantify physiological cerebral venous haemodynamics • Flow quantification within cerebral sinuses reveals high reliability and accuracy of 4D flow MRI • Blood flow volume and velocity increase along the superior sagittal sinus • Limited spatial resolution currently precludes flow quantification in small cerebral veins.

The great imitator--still today! A case of meningovascular syphilis affecting the posterior circulation.

Cerebral ischemia due to meningovascular syphilis is rare and more frequently affects the anterior circulation than the posterior circulation. We describe clinical features and imaging studies of a 50-year-old patient with Parinaud syndrome and a syphilitic dorsal midbrain infarction. Brain magnetic resonance imaging indicated vasculitis of the posterior circulation. The diagnosis of meningovascular syphilis was established by serum and cerebrospinal fluid examinations. Although rare, because of the high impact on treatment, clinicians should always be aware of meningovascular syphilis in the differential diagnosis of stroke, particularly in young and male patients with cryptogenic stroke.

Primary Epstein-Barr virus infection with polyradiculitis: a case report.

BACKGROUND: Nervous system complications of primary Epstein-Barr virus (EBV) infection in adults are rare, but may occur with encephalitis, meningitis, myelitis, cranial and peripheral neuropathies, or radiculitis. CASE PRESENTATION: We describe an immune competent adult with a primary EBV infection complicated by lumbosacral polyradiculitis with pure radicular pain. Prior to the onset of radicular pain the 35-year-old woman had been suffering from infectious mononucleosis misdiagnosed for streptococcal tonsillitis. The diagnosis of primary EBV infection associated polyradiculitis was proven by serology and PCR in serum and CSF. Under initially started empiric therapy with intravenous acyclovir and analgesics the patient completely recovered within a few days. CONCLUSION: This case report highlights that EBV should be taken into consideration in the diagnostic work up of radicular pain syndromes, even in immune competent adults. There is no approved causal therapy for EBV infections. In accordance with our case, observations based on a few patients with EBV and nervous system involvement suggest, that acyclovir treatment might be associated a with better course. However, prospective randomized controlled trials addressing the question of the effectiveness of acyclovir in patients with primary EBV infection and neurological complications are lacking.

Reproducibility and accuracy of optic nerve sheath diameter assessment using ultrasound compared to magnetic resonance imaging.

BACKGROUND: Quantification of the optic nerve sheath diameter (ONSD) by transbulbar sonography is a promising non-invasive technique for the detection of altered intracranial pressure. In order to establish this method as follow-up tool in diseases with intracranial hyper- or hypotension scan-rescan reproducibility and accuracy need to be systematically investigated. METHODS: The right ONSD of 15 healthy volunteers (mean age 24.5 ± 0.8 years) were measured by both transbulbar sonography (9 - 3 MHz) and 3 Tesla MRI (half-Fourier acquisition single-shot turbo spin-echo sequences, HASTE) 3 and 5 mm behind papilla. All volunteers underwent repeated ultrasound and MRI examinations in order to assess scan-rescan reproducibility and accuracy. Moreover, inter- and intra-observer variabilities were calculated for both techniques. RESULTS: Scan-rescan reproducibility was robust for ONSD quantification by sonography and MRI at both depths (r > 0.75, p ≤ 0.001, mean differences < 2%). Comparing ultrasound- and MRI-derived ONSD values, we found acceptable agreement between both methods for measurements at a depth of 3 mm (r = 0.72, p = 0.002, mean difference < 5%). Further analyses revealed good inter- and intra-observer reliability for sonographic measurements 3 mm behind the papilla and for MRI at 3 and 5 mm (r > 0.82, p < 0.001, mean differences < 5%). CONCLUSIONS: Sonographic ONSD quantification 3 mm behind the papilla can be performed with good reproducibility, measurement accuracy and observer agreement. Thus, our findings emphasize the feasibility of this technique as a non-invasive bedside tool for longitudinal ONSD measurements.

Enlarged Optic Nerve Sheath in Aneurysmal Subarachnoid Hemorrhage despite Normal Intracranial Pressure.

INTRODUCTION: This study investigates the diagnostic value of optic nerve sheath diameter (ONSD) assessed by transorbital sonography for estimation of intracranial pressure (ICP) in patients with aneurysmal subarachnoid hemorrhage (SAH). METHODS: Simultaneous measurements of the ONSD and ICP in 27 patients suffering from SAH and acute hydrocephalus after placement of an extraventricular drain. RESULTS: Despite normal mean ICP values ONSD was significantly higher in patients with SAH compared with healthy volunteers and no relevant decline of ONSD over time could be identified. In addition, no correlation between ONSD and ICP was observed. CONCLUSIONS: In patients with SAH and acute hydrocephalus after aneurysm rupture, the ONSD remains expanded after normalization of ICP. This is most likely due to an impaired retraction capability of the optic nerve sheath. This finding should be considered when using transorbital sonography in the neuromonitoring of aneurysmal SAH.

Terson's Syndrome: Diagnostic Comparison of Ocular Sonography and CT.

BACKGROUND AND PURPOSE: To assess the accuracy of ocular B-mode sonography and of standard head computed tomography (CT) as screening tools for intraocular hemorrhages related to subarachnoid hemorrhage (SAH). METHODS: 46 patients with spontaneous SAH were examined using ocular B-mode sonography and underwent funduscopy as gold standard for detection of ocular hemorrhages (OH). Additionally, all head CT scans done during the hospital stay of the study population were rated by a neuroradiologist for the presence of OH. RESULTS: Funduscopy revealed vitreous and/or preretinal hemorrhages in ten eyes and retinal hemorrhages in nine eyes. In comparison with funduscopy, ocular sonography showed a sensitivity and specificity for the detection of vitreous and/or preretinal hemorrhages of 100%, while identification of retinal hemorrhages was less reliable with a sensitivity/specificity of 44%/100%. Standard head CT showed a lower sensitivity/specificity of 60%/96% for vitreous and/or preretinal hemorrhages, and 32%/95% for the diagnosis of any ocular bleeding. CONCLUSION: Ocular sonography identifies SAH-related preretinal and vitreous hemorrhages with high accuracy and is superior to standard head CT. It may be considered as new and useful bedside diagnostic tool for routine clinical care of patients with SAH.

Therapeutic hypothermia in cerebral air embolism: a case report.

BACKGROUND: Cerebral air embolism is a life-threatening complication of various diagnostic and therapeutic procedures. Hyperbaric oxygenation is considered to be the cornerstone of its treatment. CASE DESCRIPTION: We report a patient with cerebral air embolism after endoscopy of a perineal abscess. Immediate CT imaging confirmed the diagnosis and MRI showed cortically localized areas of restricted diffusion along the gyri. Since hyperbaric oxygenation was not available, moderate hypothermia was applied for neuroprotection. CONCLUSION: This case illustrates a rare complication of endoscopic interventions, and imaging characteristics of cerebral air embolism were described. Furthermore, we discuss the potential utility of therapeutic hypothermia in cerebral air embolism.

Sonographic assessment of the optic nerve sheath and transorbital monitoring of treatment effects in a patient with spontaneous intracranial hypotension: case report.

OBJECTIVE: To investigate the potential of the ultrasound-based evaluation of the optic nerve sheath in a patient with spontaneous intracranial hypotension due to cervical cerebrospinal fluid (CSF) leakage. METHODS: Repeated measurements of the optic nerve sheath diameter (ONSD) using B-mode sonography were performed before treatment initiation, during medical treatment, and during a course of repeated placement of epidural blood patches. RESULTS: On admission, transorbital sonography revealed a decreased ONSD of 4.1 mm on the right and 4.3 mm on the left side. After 8 months of treatment with caffeine and computed tomography-guided epidural blood patches a gradual distension of the ONSD into the normal range was bilaterally observed (right: 5.2 mm; left: 5.3 mm). CONCLUSIONS: The ultrasound-based evaluation of the optic nerve sheath may be helpful in detecting CSF hypovolemia and for determination of treatment effects. This report should be seen as a basis for future investigations on the sonographic assessment of the optic nerve sheath in diagnosis and treatment of intracranial hypotension.

Intra- and interobsever reliability of sonographic assessment of the optic nerve sheath diameter in healthy adults.

BACKGROUND: The use of an ultrasound-based evaluation of the optic nerve sheath diameter (ONSD) has previously been demonstrated for detecting raised intracranial pressure. In order to be feasible in clinical workup, the test qualities of transorbital ultrasonography need to be determined. The aim of this study was therefore to establish normal values and to assess the intra- and interobserver reliability of this method. METHODS: Using a 9-3 MHz linear array transducer, the ONSD of 40 healthy subjects was independently measured by 2 investigators. RESULTS: Depicting the optic nerve and its sheath was possible in all individuals. The mean ONSD was 5.4 ± .6 mm with a range of 4.3-7.6 mm. The intraobserver reliability analyzed with Cronbach's Alpha was found to be high with values between .92 and .97. Pearson's correlation coefficient between the 2 investigators was .81 on the right side and .84 on the left. There was no correlation between ONSD and age, body mass index, or gender. CONCLUSIONS: Transorbital B-mode sonography is a feasible method to assess the ONSD with a high intra- and interobsever reliability. Normal values on ONSD are presented in this study that will be useful in future studies on pathological conditions.

Sonographic assessment of the optic nerve sheath in idiopathic intracranial hypertension.

The aim of this work was to investigate the potential of ultrasound-based optic nerve sheath diameter (ONSD) measurements in detecting raised intracranial pressure in patients with idiopathic intracranial hypertension (IIH) and to describe ONSD response to lumbar puncture. In ten patients with newly diagnosed IIH, transorbital sonography was carried out to assess ONSD, OND (optic nerve diameter), and optic disc elevation before and after lumbar puncture. Twenty-five patients with other neurological disorders served as controls. Subjects with IIH showed a significantly enlarged ONSD on both sides (6.4 ± 0.6 mm vs. 5.4 ± 0.5 mm in controls; p < 0.001). The best cut-off value of ONSD for detecting raised ICP was 5.8 mm with a sensitivity of 90% and a specificity of 84%. After lumbar puncture, ONSD decreased bilaterally (right 5.8 ± 0.7 mm, p < 0.004; left 5.9 ± 0.7 mm, p < 0.043). No post-puncture changes could be observed with regard to OND and optic disc elevation. Sonographic ONSD evaluation may be useful as an additional tool to identify patients with raised intracranial pressure, as in IIH. Furthermore, our data suggest a potential usefulness of this method for monitoring of treatment effects. The degree of ONSD response to lumbar puncture differs in subjects with IIH, which may possibly be related to findings of a defective CSF circulation in the optic nerve sheath in this disorder, a state that is referred to as optic nerve compartment syndrome.

Depletion of mitochondrial DNA in liver under antiretroviral therapy with didanosine, stavudine, or zalcitabine.

The "D drug" HIV reverse-transcriptase inhibitors zalcitabine, didanosine, and stavudine are relatively strong inhibitors of polymerase-gamma compared with the "non-D drugs" zidovudine, lamivudine, and abacavir. D drugs deplete mitochondrial DNA (mtDNA) in cultured hepatocytes. This mtDNA depletion is associated with an increased in vitro production of lactate. To investigate the origin of hyperlactatemia in HIV-infected patients and the effects of antiretroviral therapy on liver mtDNA, we biopsied liver tissue from 94 individuals with chronic hepatitis C virus (HCV) infection. Eighty subjects were coinfected with HIV. Serum lactate was measured at the time of biopsy. Hepatic mtDNA and liver histology were centrally assessed. Liver mtDNA content of HIV-infected patients receiving D drugs at the time of biopsy (n = 34) was decreased by 47% (P<.0001) compared with those without D drugs (n = 35). Aside from a possible association between HCV genotype I status and mtDNA depletion in multivariate analysis, there were no other virologic, immunologic, histologic, demographic or treatment-related variables that could explain the mtDNA depletion. Lactate was above the upper limit of normal in only three patients, all of whom were treated with D drugs. The mtDNA in each of them was lower than in any non-D drug patient and significantly (P =.017) depleted compared with D drug patients with normal lactate. In conclusion, D drug treatment is associated with decreased hepatic mtDNA in HIV-infected patients with chronic HCV infection. Moderate mtDNA depletion in liver does not necessarily lead to hyperlactatemia, but more pronounced decreases in hepatic mtDNA may be an important contributor to lactate elevation.