Biomedical subjects
G Orlandi
Publications and source records attributed to G Orlandi.
Incidence of intracranial hypertension related to jugular bulb oxygen saturation disturbances in severe traumatic brain injury patients.
OBJECTIVE: To analyze the Intracranial Hypertension (IH) development related to jugular bulb oxygen saturation (SjO2) disturbances in severe traumatic brain injury patients (sTBI). MATERIALS AND METHODS: One hundred and thirty-five sTBI patients were reviewed. Those without IH at admission (n = 116) were included. All patients underwent ICP and SjO2 continuous monitoring. Two groups were distinguished according to the SjO2 values during the first 24 hours. Group A: those with abnormal SjO2 (SjO2 more than 75% or less than 55%) and Group B: those with normal SjO2 (55-75%). Differences in IH development and outcome between groups were analyzed. Causes of abnormally low SjO2 were identified. RESULTS: IH developed in 56.9% of patients, between 12 and 48 hours from admission. Group A had a significantly higher incidence of IH than Group B (p < 0.001) and it also had a worse outcome than Group B (GOS 1-2) (p < 0.005). Patients from Group A had a risk of IH 4.5 fold higher than Group B. Considering only patients who developed IH, an abnormal SjO2 value increased 2.3 fold the risk of death compared to those without SjO2 disturbances. Main causes of SjO2 desaturation were hyperventilation (40.7%), hypovolemia (28.4%) and anemia (21%). CONCLUSIONS: Early detection of disturbances in oxygen supply-demand relationship and prevention or resolution of the secondary insults which produce these disturbances, might lead to a reduction in the incidence of intracranial hypertension.
Dissection and atherosclerosis of carotid arteries in the young: role of the apolipoprotein E polymorphism.
Twenty-seven young (<50 years old) patients with spontaneous carotid artery dissection in 11 cases and carotid atherosclerosis in 16 cases were evaluated to determine the apolipoprotein E polymorphism. At the DNA analysis the epsilon3/epsilon3 genotype was observed in all patients with dissection, in 13 of 16 (81.2%) patients with atherosclerosis and in 27 of 30 (90%) controls. Three of 16 (18.8%) patients with atherosclerosis and 3 of 30 (10%) controls presented with the epsilon4/epsilon3 genotype, and this difference was not statistically significant. Moreover, observation of the epsilon4/epsilon3 genotype was not significantly higher in patients with atherosclerosis compared with those with dissection. No homozygote epsilon4/epsilon4, epsilon2/epsilon2 or heterozygote epsilon2 genotype was observed. No correlation was found between the presence of the epsilon4/epsilon3 genotype and vascular risk factors. Therefore, the epsilon4 allele seems to be involved in carotid premature atherosclerosis development whereas it may appear to be protective for artery dissection occurrence. A larger sample size is needed to support this suggestion.
Measurements of coherent diffraction radiation and its application for bunch length diagnostics in particle accelerators.
Measurements of coherent diffraction radiation from a slit of variable width generated by short electron bunches were performed in millimeter and submillimeter ranges. Experimental data are compared with the transition radiation case and theoretical predictions. A more realistic description than the conventional theory is necessary to account for the data correctly. No noticeable difference in the estimated bunch length was observed using diffraction radiation in a wide range of slit widths and transition radiation.
Characteristics of cerebral microembolism during carotid stenting and angioplasty alone.
BACKGROUND: Cerebral microembolism has often been documented by transcranial Doppler imaging during carotid angioplasty and stenting. However, few data are available about its characteristics during the 2 different kinds of procedure. OBJECTIVES: To compare the incidence of microemboli occurring during angioplasty alone with that during stenting in the different phases of the procedures and to relate it to periprocedural cerebrovascular complications. PATIENTS AND METHODS: Thirty-eight patients underwent 41 procedures (15 angioplasty alone and 26 stenting) for symptomatic carotid stenoses of 70% or more. Transcranial Doppler monitoring was performed to detect microemboli in the middle cerebral artery during 3 phases of the procedure: (1) guidewire crossing, (2) first dilatation in case of angioplasty alone or stent release with predilatation if performed, and (3) further dilatation. RESULTS: Microemboli occurred in all cases in phase 1 of the procedure but less frequently in the arteries treated with stenting when compared with those treated with angioplasty alone in phase 2 and particularly (P<.02) in phase 3. The mean number of microemboli was highest in phase 2, predominant (P<.05) during angioplasty alone, and particularly reduced (P<.02) in phase 3 during the stenting procedures. During 2 (5%) of the 41 procedures, cerebrovascular complications occurred in phase 1, with the number of microemboli being higher than mean values. CONCLUSIONS: Cerebral microembolism is a very common event, especially during guidewire crossing and angioplasty alone compared with stenting. Further studies concerning the prognostic significance of this are advisable.
Early thrombolysis in stroke due to basilar artery occlusion.
Basilar artery occlusion is usually associated with a poor prognosis. Nevertheless, intra-arterial thrombolysis has been shown to improve clinical outcome in selected cases. We report the case of a 29-year-old patient who suffered a severe ischemic stroke due to basilar artery occlusion and who was treated with intra-arterial thrombolysis within 3 h of symptoms onset; treatment was followed by an almost full functional recovery. The young age of the patient, short segment occlusion in the middle tract of the artery, good collateral supply, and early recanalization may account for the favorable prognosis.
Asymmetric scalp distribution of pattern visual evoked potentials during interictal phases in migraine.
The N70 and P100 components of transient pattern visual evoked potentials (P-VEPs) were measured in migraine patients, with and without aura, and in normal subjects in order to evaluate their latency, amplitude and occipital scalp distribution. The aim was to find any typical electrophysiological abnormalities in migraine. P-VEP N70 and P100 were analyzed in 59 patients without any known visual field defect. Mean latency and amplitude values were within normal ranges for either N70 and P100 all over the occipital scalp; the only significant abnormality we found was related to the absolute right-left amplitude ratio either for N70 and P100 waves, providing an asymmetry in P-VEP scalp distribution; this finding was detected in 78.9% of patients with aura and 72.5% without aura. Our results show that in migraine patients, both P-VEP waves N70 and P100, have an asymmetric topographic distribution, even during interictal phases, that can be explained by a cortical disturbance in agreement with the neural hypothesis of headache.
Transient autonomic nervous system dysfunction during hyperacute stroke.
Forty-four patients suffering a stroke for the first time were examined within 10 h of the onset of symptoms; the tests performed on their admission to hospital, and thereafter on the third and seventh day, were 24-h Holter EKG with spectral analysis of heart rate variability, evaluation of arterial blood pressure and the levels of catecholamine in the blood and 24-h urine. The dynamic EKG on admission revealed that 31 (70.5%) out of the 44 patients already had arrhythmia. These alterations were observed in 9 (75%) out of 12 haemorrhagic patients with a significant (P < 0.05) prevalence compared to 22 (68.8%) of the 32 ischaemic ones. Arrhythmia showed up in 16 (76.2%) out of 21 cases with right hemisphere lesions and in 12 (63.2%) out of 19 cases of left hemisphere lesions; this difference was also significant (P<0.05). Arrhythmia was still present in 19 (43.2%) patients after 3 days and only in 2 (6.5%) patients after 7 days. The spectral analysis parameters on admission and after 3 days were significantly (P < 0.05) modified in patients with stroke plus arrhythmia, compared to patients with stroke alone and to control subjects, whereas no further differences were observed on the seventh day. Moreover, the percentage of patients with arterial hypertension and high levels of catecholamine greatly decreased from the third day onwards. A transient autonomic nervous system imbalance with prevalent sympathetic activity may justify this cardiovascular impairment during the hyperacute phase of stroke.
Plaque surface and microembolic signals in moderate carotid stenosis.
We performed Transcranial Doppler Monitoring to detect microembolic signals (MES) in 47 patients with moderate (30%-69%) carotid stenosis proven by selective angiography. We compared the occurrence of MES with the clinical characteristics of stenosis (symptomatic or asymptomatic) and the angiographic plaque features (nonulcerated, deep ulceration, superficial ulceration, ulceration with flap, or ulceration without flap). For these cases there was no indication for endarterectomy, nevertheless we thought it would be useful to identify risk subgroups that might benefit from surgical treatment. MES were detected in 17.9% of the stenoses with a prevalence (p <. 01) in symptomatic cases (25%) compared to asymptomatic cases (14. 3%). There was a significant correlation of MES with plaque ulceration (p <.01) and particularly with ulceration without flap (p <.01). No difference between deep and superficial ulceration was observed. The availability of prospective data on this topic might be useful to select subgroups of patients with moderate carotid stenosis at risk for embolism.
Vertebral and carotid artery dissection following chiropractic cervical manipulation.
A 50-year-old woman presented a sudden left occipital headache and a posterior circulation stroke after cervical manipulation for neck pain. Magnetic resonance imaging documented a left intracranial vertebral artery occlusive dissection associated with an ipsilateral internal carotid artery dissection with vessel stenosis in its prepetrous tract. This is the first reported case showing an associate vertebral and carotid artery dissection following cervical manipulation. Carotid dissection was asymptomatic and, therefore, its incidence may be underestimated. We emphasize that cervical manipulation should be performed only in patients without predisposing factors for artery dissection and after an appropriate diagnosis of neck pain.
[High-intensity transcranial Doppler signals in patients wearing heart valve prostheses: a prospective study].
BACKGROUND: Transcranial Doppler sonography (TCD) of the middle cerebral arteries in patients with prosthetic heart valves reveals high-intensity transient signals (HITS) and can detect asymptomatic cerebrovascular microemboli. Both the nature of the underlying embolic material (either gaseous or corpuscular) and its clinical significance remain uncertain. METHODS: Seventy-one patients undergoing heart valve replacement (n = 63) or repair (n = 8) from June 1996 to June 1998 were prospectively evaluated preoperatively and one week, 3 months and 12 months after valve replacement using TCD. At each follow-up interval, clinical assessment was aimed at detecting neurological events. Furthermore, continuous echo-Doppler study of the carotid arteries and TCD of the middle cerebral arteries for a 30-minute period during each following visit was carried out. RESULTS: No HITS were recorded preoperatively in any patient. At one week, HITS were detected in 25 patients (35%): 22 (65%) of these had received a mechanical prosthesis and three (10%) a bioprosthesis. No HITS were recorded in patients with mitral repair. HITS were subsequently detected only in patients with mechanical prosthesis with a positive TCD at one week, the mean number of HITS per patient being 7 +/- 18 at 3 months and 8 +/- 24 at 12 months. No neurological symptoms were evident in any patients during the postoperative evaluation. Multivariate analysis showed mechanical prosthetic valve to be the only independent predictive risk factor for HITS development. CONCLUSIONS: The role of a mechanical prosthetic valve as a risk factor in the pathogenesis of HITS appears evident. However, HITS appear to be unrelated to possible postoperative neurological events. TCD could have more specific clinical applications if associated with methods that would make it possible to ascertain the nature of various embolic materials.
Prospective evaluation of frequency and nature of transcranial high-intensity Doppler signals in prosthetic valve recipients.
BACKGROUND AND AIM OF THE STUDY: In asymptomatic prosthetic valve recipients, high-intensity transient signals (HITS) observed with transcranial Doppler (TCD) are a phenomenon of obscure clinical relevance which nature has not yet been elucidated convincingly. METHODS: Eighty-three patients without carotid disease, history of cerebrovascular accidents, and with negative preoperative TCD undergoing either valve replacement (mitral, n = 11; aortic, n = 56; mitral + aortic, n = 6; 40 mechanical prostheses, 29 biological prostheses, 10 homografts) or mitral repair (n = 10) were evaluated prospectively by means of TCD at discharge, three months and one year after surgery, to analyze the presence, incidence and characteristics of HITS. Furthermore, in 12 patients positive for HITS, TCD was repeated during a 30-min period of 100% O2 inhalation. RESULTS: Twenty-five patients (30%) were positive for HITS at all postoperative controls, although no neurological symptoms were observed. Mechanical prostheses showed a significantly higher incidence of HITS (85%) than biological prostheses (10%, p <0.001), repaired mitral valves (0%, p <0.001) and homografts (0%, p <0.001). At multivariate analysis the presence of a mechanical prosthesis was the only significant predictor of detection of HITS after valve replacement. During O2 inhalation, a significant decrease in the number of HITS per hour (55 +/- 79 versus 22 +/- 31, p = 0.002) occurred, which returned to initial values when room-air breathing was resumed. CONCLUSIONS: Prosthetic valve replacement, particularly when mechanical devices are used, is associated with the generation of HITS which persist throughout the follow up period, but remain clinically silent. The decrease of HITS during O2 inhalation strongly supports the hypothesis of the gaseous nature of such signals and confirms the validity of this method in helping to differentiate gaseous microemboli from solid microemboli in prosthetic valve recipients.
Bilateral medial frontal infarction in a case of azygous anterior cerebral artery stenosis.
We describe the unusual case of a 63-year-old woman with a history of arterial hypertension who presented a sudden weakness of the lower limbs followed by mutism, akinesia and dyspraxia. Magnetic resonance images showed a bilateral medial frontal infarction. Digital subtraction angiography documented a right azygous anterior cerebral artery with severe stenosis in its sub-callosal tract; the left anterior cerebral artery showed mild hypoplasia with only sub-frontal and fronto-polar branches. No embolic source was documented. Afterwards the patient presented a gradual and partial recovery of both motor and cognitive functions.
Factor V Leiden mutation in a case with ischemic stroke: which relationship? A case report.
A 50-year-old man presented spontaneous internal carotid artery dissection with ischemic stroke. He had a history of deep venous thrombosis, and an activated protein C resistance due to factor V Leiden mutation was documented. He showed no other vascular risk factor. This unusual case puts the question whether this coagulation defect may be related to the stroke occurrence.
Carotid plaque features on angiography and asymptomatic cerebral microembolism.
We studied 110 carotid arteries of 55 patients with unilateral or bilateral carotid stenosis diagnosed with selective angiography, by using Transcranial Doppler to detect high intensity transient signals (HITS) in the middle cerebral arteries (MCAs). HITS identified as embolic signals were prevalent (P < 0.05) in the MCAs on the same side as severe (70-99%) stenosis (22 of 51 = 43.1%) compared to moderate (30-69%) stenosis (5 of 37 = 13.5%). No HITS were observed in the MCA on the same side as normal control carotid arteries (n = 17) [occluded arteries (n = 5) were not considered]. HITS were more prevalent (P < 0.05) in the MCAs on the same side as ulcerated plaques (14 of 23 = 60.9%) compared to non-ulcerated plaques (13 of 65 = 20%), and all moderate stenoses producing HITS presented ulceration of the plaque. Ulcerated plaque groups showed a higher mean number of HITS than non-ulcerated plaque groups and no significant difference was noted between moderate and severe stenosis, between superficial or deep ulcerations and between ulcerations with flap or without flap. Therefore, severe carotid stenosis and moderate stenosis with plaque ulceration result in angiographic findings most frequently associated with HITS. Further studies are necessary to evaluate the clinical significance of this finding.
Silent cerebral microembolism in asymptomatic and symptomatic carotid artery stenoses of low and high degree.
124 carotid arteries of 62 patients with unilateral or bilateral carotid stenosis proven by selective angiography were investigated by transcranial Doppler to detect high-intensity transient signals (HITS) in the middle cerebral arteries (MCAs). HITS identified as embolic signals were detected in 29 of 124 (23.3%) MCAs and in all cases were asymptomatic. HITS were more common in the MCAs on the same side as high-degree (> 70%) carotid stenoses (24 of 57 = 42.2%) compared with low-degree (< 70%) carotid stenoses (5 of 28 = 17.9%, p < 0.05). No HITS were detected in the MCAs on the same side as normal (24) and occluded (15) carotid arteries. About the clinical features related to the stenoses, HITS were detected with a nonsignificant prevalence in the MCAs on the same side as symptomatic stenoses (16 of 43 = 37.2%) compared with asymptomatic stenoses (13 of 42 = 30.9%) and a relationship between HITS number and time elapsed from symptoms was observed. All symptomatic carotid stenoses > 70% (33) underwent endarterectomy and none of them showed HITS after surgical treatment. These results encourage the feasibility of prognostic studies to evaluate the clinical significance of embolic signals and suggest that silent microembolism could be helpful in selecting a high-risk group of asymptomatic or < 70% carotid stenoses for endarterectomy.
Cerebral oximetry during carotid endarterectomy.
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Long-term in vitro precision of single slice peripheral Quantitative Computed Tomography (pQCT): multicenter comparison.
In a multicenter evaluation the precision and stability of single slice peripheral Quantitative Computed Tomography (pQCT) systems were assessed. Compared to central Europe the peripheral QCT device is also widely used in the Italian health care system. Phantoms were measured frequently on each machine in four pQCT scanners over a two-year period using an identical automated software program. Intrasite and intersite phantom mineral densities, expressed in units of mg/cm3, were analyzed and examined. The short and long term precision were estimated from the consistency of these measurements using the root mean square error and expressed as coefficient of variation in percent (% CV). Short term precision was good (mean intrasite coefficient of variation (CV) 0.21 +/- 0.056 standard deviation (SD)). Intersite measurements of a single phantom revealed differences between machines of the same type of not more than 2.9 mg/cm3. At four sites frequent phantom measurements revealed a mean CV of 0.18% (range 0.12-0.28). No significant changes in the regression slopes (drift of the machine versus time) were observed. We conclude that the in vitro precision and stability of the single slice pQCT systems are sufficiently high and unlikely to negatively affect the in vivo precision.