Absorption coefficients and scattering losses of TGG, TGP, KTF, FS, and CeF3 magneto-optical crystals in the visible via cavity ring-down spectroscopy.

We demonstrate a method for determining small absorption coefficients and surface-scattering losses of crystals using cavity ring-down spectroscopy and perform measurements on magneto-optical crystals of terbium gallium garnet (TGG), terbium gallium phosphate (TGP), fused silica (FS), potassium terbium fluoride (KTF), and C e F 3 at 532 and 634 nm. Surface scattering is distinguished from absorption losses by using crystals of different lengths. A figure of merit (FoM) for magneto-optical crystals is defined to evaluate their suitability as intracavity optics in optical cavity applications. It is found that TGP has the highest FoM for crystal lengths up to ∼10m m, whereas C e F 3 and FS potentially outperform TGP for longer crystals. Single-pass applications are also briefly discussed.

Predictable ventricular shift after focal cerebral ischaemia in rats: practical considerations for intraventricular therapeutic interventions.

Intracerebroventricular (ICV) route of administration is a useful experimental method to study the effects of chemicals or cellular grafts in the ventricular compartment of the brain after focal ischaemia. However, the induced oedema may cause structural dislocating phenomena and render a stereotaxic ICV invasion difficult and practically unavailable especially during the acute post-ischaemia phase. The aim of this study was to measure these structural ventricular dislocations and set new stereotaxic coordinates for successful and cost-effective ICV invasion 6-18 h after focal cerebral ischaemia. Wistar rats were subjected to 2 h middle cerebral artery occlussion (t-MCAO), were neurologically evaluated (modified Neurological Stroke Scale [mNSS], modified Bederson's Scale [mBS] and grid-walking test [GWT]) and brain slides were studied at 6 and 18 h post-occlusion for infarction volume, hemispheric oedema, middle line dislocation and stereotaxia of the lateral ventricles. Our data indicated that stereotaxic coordinates of the lateral ventricles in the infarcted and contralateral hemispheres significantly (P < 0.05) changed at both time-points and were linearly correlated with the mNSS, mBS and some GWT scores (P < 0.001). This correlation allowed for the calculation of simple (linear) mathematical equations (stereotaxic coordinate = b0 + b1*mNSS, where 'b0' and 'b1' are fixed number and factor, respectively, calculated by regression analysis) that determined individually new coordinates for each animal. Verification experiments revealed that the new coordinates render ICV invasion feasible in up to 80% of infarcted rats (number needed to treat 1.65), compared with only 19.4% using the classical coordinates for normal rats. Therefore, we propose a new, time- and cost-effective methodology for practically feasible ICV invasion in rats 6-18 h after t-MCAO.

Is there or is there not a place for anti-interferon antibodies in the decision making of multiple sclerosis treatment optimisation?

Several factors contribute to the fact that not all multiple sclerosis (MS) patients respond equally well to long-term interferon beta (IFNbeta) treatment, even if the initial response is adequate. Among these factors, anti-interferon neutralising antibodies (NAbs) may be included. There is increasing evidence that these antibodies have a clinical impact in MS treated patients, which is evident some months following the initiation of treatment with IFN?. Several efforts to reduce the concentration of NAbs, especially when they are in high titres and clinically active, have failed. However, the same efforts may be more effective if applied following early detection of the antibodies, thus leading to a continuation of the initially selected interferon treatment.

Carotid plaque echomorphology and serum vascular endothelial growth factor levels.

Neovascularization in atherosclerotic plaques plays an essential role in the progression and rupture of plaques. Vascular endothelial growth factor (VEGF) is an important angiogenic factor. Echomorphologic evaluation of carotid plaques using computer-assisted imaging was found to have a good correlation with the histology of the lesion. The aim of this study was to investigate whether the serum VEGF level could be a determinant of the echomorphology of the carotid plaque. In 28 carotid plaques causing 60-99% stenosis, serum VEGF levels and the mean gray value (MGV) of three-dimensional image of the carotid plaques were measured. A statistically significant inverse correlation was found between serum VEGF concentrations and MGVs (Spearman's correlation coefficient: -0.415, p = 0.028). Our finding indicates that in patients with > or =60% carotid stenosis the serum VEGF levels are associated with the echogenicity of the atherosclerotic plaque.

Isolated ocular ischemic syndrome with no cerebral involvement in common carotid artery occlusion.

PURPOSE: The ocular ischemic syndrome (OIS) is sometimes a complication of common carotid artery (CCA) occlusion causing complete interruption of blood flow through both the internal and external carotid arteries we investigated a single case of an isolated OIS that remained undiagnosed for two years, because the underlying CCA pathology caused no cerebral involvement. CASE REPORT: A 57-year-old man presented with subacute painful visual loss in the right eye in a setting of hypertension, smoking and coronary artery disease. RESULTS. Neurological examination, a brain CT and MRI scan were all normal. Extensive laboratory work-up excluded small artery disease, inflammatory arteritis or cardiac causes of retinal embolism. Ophthalmologic evaluation and fluorescein angiography gave findings consistent with OIS, while vascular ultrasound evaluation and aortic arch angiography verified right CCA occlusion accompanied by an extensive collateral network. CONCLUSIONS: Had this patient been referred sooner for a simple carotid artery work-up, both the CCA occlusion and the OIS could probably had been prevented.

Beneficial effect of piracetam monotherapy on post-ischaemic palatal myoclonus.

A 70-year-old hypertensive woman suffered a subarachnoid haemorrhage followed by delayed vasospasm in the basal cerebral arteries. This resulted in multiple ischaemic lesions in the right middle cerebral artery region and contralateral post-ischaemic palatal myoclonus. In this setting, piracetam administered in high doses (24-36 g/day), abolished the myoclonus observed in this patient. Although there is evidence from case reports and clinical trials of the therapeutic efficacy of piracetam in patients with skeletal myoclonus of various causes, to our knowledge this is the first report indicating the beneficial effect of piracetam monotherapy on post-ischaemic palatal myoclonus.

Cobalamin deficiency: MRI detection of posterior columns involvement and posttreatment resolution.

Cobalamin-deficient myelopathy is a neurologic disorder manifesting progressive symptoms of paresthesiae and spastic paralysis. The pathologic changes initially involve the posterior columns of the cervical and upper thoracic cord. The authors present the case of a patient with cobalamin deficiency with preferential posterior columns involvement, as evidenced by spinal magnetic resonance imaging findings. Marked clinical and radiographic resolution occurred after administration of vitamin B12. Early recognition of this specific magnetic resonance pattern is essential, because complete recovery can be achieved with prompt treatment at this reversible stage of the disease.

Power Doppler imaging and color Doppler flow imaging for the evaluation of normal and pathological vertebral arteries.

Recently, an ultrasound method for vascular applications using the amplitude of the reflected echosignal for the generation of intravascular color signals has been introduced. We compared the utility of this power Doppler imaging (PDI) with conventional color Doppler flow imaging (CDFI) for examination of vertebral arteries (VA). Forty-nine patients with signs and symptoms suggesting ischemia within the posterior circulation were evaluated. Quality of blood flow visualization by PDI and CDFI at the different VA segments was classified according to a four point scale. Furthermore, combined sonographic findings were correlated with the results of digital substraction and/or magnetic resonance angiography (DSA, MRA). Power Doppler imaging provided a significantly superior visualization of the intertransversal VA, whereas display of the intracranial V4 segment was superior significantly on CDFI. Both methods were complementary for the evaluation of the VA at the origin. With respect to the angiographic findings, combined CDFI and PDI achieved a sensitivity of 90.63% and a specificity of 97.22% for the differentiation of healthy and pathologic VAs. Power Doppler imaging is complementary to CDFI for the sonographic assessment of VA disease. Combined use of PDI and CDFI achieves a high sensitivity and specificity, thus increasing diagnostic confidence.

Power Doppler imaging of carotid artery stenosis. Comparison with color Doppler flow imaging and angiography.

BACKGROUND AND PURPOSE: Power Doppler imaging (PDI) is a new sonographic technique that has recently been introduced for vascular application. Since the technical principles of PDI may provide increased sensitivity to visualize the continuity of blood flow in arterial stenoses, we investigated the diagnostic significance of PDI and the intermethod relationship for the measurement and classification of internal carotid artery (ICA) stenosis in comparison with both color Doppler flow imaging (CDFI) and angiography. METHODS: One hundred patients with a total of 128 ICA stenoses (50% to 69%, n = 37; 70% to 79%, n = 27; 80% to 99%, n = 64) and 12 ICA occlusions were consecutively investigated by means of PDI, CDFI, and intra-arterial angiography (n = 48). Reduction of the intrastenotic lumen was measured on longitudinal and transverse views of PDI and CDFI for the calculation of the degree of diameter and area stenosis, respectively. Angiographic stenosis was determined with the use of the North American Symptomatic Carotid Endarterectomy Trial (NASCET), European Carotid Surgery Trial (ECST), and common carotid (CC) methods. RESULTS: PDI provided significantly more excellent or good (92% versus 79%; P < .01) displays of the intrastenotic lumen than CDFI, particularly in complicated high-grade stenosis. While linear regression analysis demonstrated a high overall correlation between PDI and CDFI for diameter (r = .88; P < .001) and area stenosis (r = .79; P < .001), categorization of ICA stenosis revealed best agreement for 80% to 99% area stenoses. Since angiography frequently either underclassified (NASCET method) or overclassified (ECST, CC methods) the degree of ICA stenosis in comparison to both PDI and CDFI, the sonographic-angiographic correlation was only moderate (regression coefficients ranged from .62 to .70; P < .001). CONCLUSIONS: PDI further improves the assessment of ICA stenosis by providing better visualization of the stenotic vascular lumen than CDFI. Sonographic imaging of the stenotic plaque on both PDI and CDFI provided a direct measurement of the local degree of stenosis, while the angiographic grade of stenosis essentially depended on the method used for evaluation.

Bilateral thalamic infarcts presenting as acute pseudobulbar palsy.

A 28-year-old, previously healthy, normotensive woman suddenly developed an acute pseudobulbar palsy with dysarthria, dysphagia, hypernasal voice and mild right arm paresis. Extensive laboratory investigations excluded all other possible causes of acute pseudobulbar palsy (neoplastic, inflammatory, demyelinative, myasthenic) and an MRI study demonstrated bilateral isolated thalamic infarcts. Oral contraceptives and smoking were the only possible stroke risk factors found and cerebral diaschisis the most tenuous explanation proposed. To our knowledge, this is the first report indicating that bilateral thalamic infarction on specific nuclei could be manifested as acute pseudobulbar palsy.

Delayed diagnosis of spinal vascular malformations presenting as intermittent myelopathy.

We report our recent experience of three male patients, whose clinical diagnosis and subsequent surgery was delayed for 9.25 and 15 months respectively. Initially, they all presented with vague, either sensory or motor lower limb disturbances and intermittency of symptoms was followed by bladder dysfunction or impotence. Extensive laboratory work-up was unrevealing and the non-specific diagnosis of myelopathy further delayed the recognition of the underlying vascular lesion. Finally spinal magnetic resonance imaging (MRI), supine myelography and selective spinal arteriography indicated the presence of a tumor in the first patient and vascular malformation in the other two. Neurosurgery and histology confirmed one cavernous angioma and two arteriovenous malformations, all thoracic and dural. We believe that both the cryptic nature of these lesions and our technical limitations (spinal arteriography and MRI not readily available), accounted for the delayed diagnosis in our three patients, who nevertheless, when treated by surgery showed a satisfactory outcome in the first case, while further deterioration was prevented in the other two.

Case report: epidural and bilateral retroorbital hematomas complicating sickle cell anemia.

Early in the course of a painful crisis, a 19-year-old man with known sickle cell anemia (SCA) developed a clinical picture that resembled either early cavernous sinus thrombosis or retroorbital and bifrontal microinfarcts. A brain computer tomography scan demonstrated bilateral retroorbital hemorrhages along with a left frontal epidural hematoma. In the absence of trauma, thrombocytopenia, or any other detectable hemostatic defect, this type of hemorrhagic manifestation in the setting of SCA has not, to our knowledge, been previously reported in the literature.

Ischemic infarct in childhood secondary to internal carotid artery dissection. Report of a case.

A previously healthy 6-year-old boy, suddenly developed a complete right hemiparesis and dysarthria while playing at school without any history of trauma. All laboratory examinations were normal except for CT brain scan that revealed a small ischemic infarct in the left middle cerebral artery territory. Four vessel cerebral angiography demonstrated a left internal carotid artery dissective obstruction while filling of the right or left vertebral artery resulted in the simultaneous retrograde appearance of the respective middle cerebral artery possibly via the posterior communicating artery. In contrast to the literature data, the patient showed a significant recovery with conservative treatment. This uncommon stroke type in children and the possible protective role of the posterior communicating artery's collateral are further discussed.

Restoration of micturition using microelectric current in experimentally induced spastic urinary bladder in rabbits.

The 29 rabbits used in this study were divided into three groups, A (A1 and A2), B, and C. In subgroup A1, 4 animals were used in order to verify whether the contact of an electrode to the sacral nerves results in some abnormality of voiding reflex. In subgroups A1 and A2 (4 animals each) we further studied the micturition function using three parameters: (i) urinary bladder fluoroscopy and radiography, (ii) cystomanometry, and (iii) electromyography of the pelvic floor muscles (external sphinter). In group B (9 rabbits) spastic paraplegia and micturition disturbances resulted from spinal cord compression that was induced by inserting a balloon catheter into the T11-T12 intervertebral foramen. In this group the parameters studied revealed a spastic urinary bladder in all animals. Finally, the 12 animals of group C were rendered paraplegic as described in group B, and microelectrodes were placed over the sacral nerves as in subgroup A1. By applying a specific sequence of sacral nerve stimulation we succeeded in satisfactory urinary bladder emptying as confirmed by the micturition parameters studied: The urinary bladder pressure decreased from 65 +/- 3 to 28 +/- 3 mm Hg. The pelvic floor muscle amplitude was lowered from 130 +/- 7 to 20 +/- 3 microV, and finally the radiological bladder size also decreased from 38 cm2 before voiding to 18 +/- 3 cm2 after voiding. These results indicate that microelectric current stimulation of the sacral nerves, when applied under a specific sequence, could rather satisfactorily restore micturition disturbances, at least in this experimental animal.

Preoperative evaluation of patients with extracranial carotid disease. Plethysmographic criteria for the use of a shunt, and for avoidance of surgery.

Eighty five angiographically studied patients (mean age 52) with carotid artery disease were preoperatively evaluated for the type and adequacy of their collateral circulation by the use of supraorbital photo-electric plethysmography (SPP). According to certain criteria we identified the candidates for surgery with or without shunt or for conservative treatment. Sixty patients presented evidence of extracranial collateral mainly from the ipsilateral superficial temporal artery (49 of 60), 11 patients revealed evidence of intracranial collateral mainly from the contralateral internal carotid artery (9 of 11), while in the rest, 14 patients, the source of the collateral circulation was undeterminable. Furthermore, an adequate circle of Willis was found in 67 patients and an inadequate one in the rest 7 (4 of 60, and 3 of 14). The majority of the surgically treated patients (74 of 81) were subjected to surgery without shunt (91%) while only 7 necessitated the use of a shunt (9%). No neurological complication was encountered and the single death (1.3%) was not directly related to the surgery itself. According to the present study, the careful preoperative determination of the collateral circulation, with the simple technique of SPP and the identification of patients at high risk under certain criteria could help the surgeon to decide about the advisability of a shunt or not and about the avoidance of surgery as well. This technique may be valuable where other more sophisticated forms of monitoring, such as EEG, evoked potentials or blood flow, are not readily available.

The evaluation of blood flow Xe133 in different degrees experimentally induced carotid stenosis.

The present study was conducted in order to detect the possible relationship between the degree of carotid artery stenosis and the morphology, width of Xe133 curves and the absolute value of blood flow volume, obtained by the intra-carotid injection of Xe133 in 21 dogs (Groups A,B,C, n = 7 in each). In Group B the morphology of Xe133 curves revealed a double peak on the vertical part and the width a 57% decrease on the same part as compared to the control (Group A), while the per min blood flow value decreased by 47%. In Group C an elevation of the horizontal part was observed in all animals, the width of the vertical part could not be measured and the horizontal part showed a 10% increase as compared to the control Group A. Finally, the per minute blood flow value decreased by 75% compared to the controls.

Carotid compression test and supraorbital photoelectric plethysmography in patients with carotid TIAs.

Fifty-two patients with carotid transient ischemic attacks (TIAs) were subjected to subsequent compression of the common carotid and superficial temporal artery. An EEG recording was monitored simultaneously with plethysmograms from both supraorbital regions during the arterial compression period. All patients were angiographically classified as normal (Group A, n = 25) with less than 50% stenosis (Group B, n = 14) and with more than 50% stenosis (Group C, n = 13), according to the degree of internal carotid stenosis. The carotid compression test was positive in 6 (11%) of our 52 patients, corresponding to 1 (4%) patient from Group A, 1 (7%) from Group B and 4 (30%) from Group C. In contrast, supraorbital photoelectric plethysmography (SOPPL) yielded abnormal results in 17 (33%) of our 52 patients, corresponding to 3 (12%) patients from Group A, 4 (28%) from Group B and 10 (77%) from Group C. We conclude that in view of the false positive results (12%) obtained with the SOPPL technique, the clinician who interprets these findings should be careful and combine these tests with other tests, preferably hemodynamic, for a final decision about the patient's status.