Abstract: After a long debate, due to conflicting data from clinical studies, homocysteine is now largely accepted as a risk factor for cardiovascular diseases including stroke. To date, the role of elevated homocysteine levels in stroke recurrences has not been evaluated. In the present issue of Clinical Science, Zhang and co-workers prove that Chinese patients with high homocysteine levels have an increased risk of stroke recurrence and of all-cause mortality with respect to patients with lower levels. Remarkably, in their study, high homocysteine levels were associated with an increased risk of stroke recurrence for atherothrombotic stroke and intracerebral haemorrhage, but not lacunar stroke. The study by Zhang and co-workers provides important information for clinical practice and represents the basis for further investigations, as it raises questions referring to the puzzling relationship between homocysteine and cardiovascular disease. Moreover, the results support the hypothesis that, for undisclosed reasons, the relationship between homocysteine and cardiovascular disease may not be homogeneous for all the conditions encompassed in the category of cardiovascular disease, being peculiar for stroke patients. The finding of an association between high homocysteine levels and a risk of recurrent stroke or all-cause mortality in patients with intracerebral haemorrhage should be taken with caution until this same result is confirmed in other case series with different ethnicity.
Abstract: Different types of migraine have been reported in 20-40% of patients with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). We describe a novel migrainous manifestation of CADASIL consisting in status migrainosus and persistent aura without infarction. The symptoms resolved after i.v. treatment with lorazepam and mannitol.
Abstract: BACKGROUND AND PURPOSE: The purpose of this study was to evaluate the incidence and prognosis of intracerebral hemorrhage. METHODS: We analyzed data referring to our prospective population-based registry, including patients with a first-ever stroke followed up to 10 years. RESULTS: In a 5-year period, we included 549 patients (247 men and 302 women; mean age+/-SD, 73.6+/-12.5 years) with an intracerebral hemorrhage. The crude annual incidence rate was 36.9 per 100000 (95% CI, 33.8 to 40.0), 32.9 per 100000 when standardized to the 2006 European population, and 15.9 per 100000 when standardized to the world population. The case-fatality rate was 34.6% (95% CI, 30.6 to 38.6) at 7 days; it increased to 50.3% (95% CI, 46.1 to 54.5) at 30 days and to 59.0% (95% CI, 54.9 to 63.1) at 1 year. Diabetes mellitus and posterior fossa hemorrhage were associated with an increased risk of 7- and 30-day mortality, whereas older age was associated with an increased risk of 30-day mortality only. At the Kaplan-Meier analysis, the 10-year survival rate was 24.1% (95% CI, 20.1 to 28.1). CONCLUSIONS: Intracerebral hemorrhage is characterized by a severe prognosis, mostly in the short term. Because of the high proportion of fatal events that occurs early after the stroke, it is mandatory to identify and apply specific therapeutic strategies for patients with intracerebral hemorrhage.
Abstract: BACKGROUND: Variations in stroke onset are related to stroke type and severity. We evaluated the impact of hourly and daily stroke onset variations on the pattern of patient hospital referral and on the time interval from stroke onset to hospital admission and brain neuroimaging investigations. METHODS: This multicenter observational study recorded all incident acute strokes within a 4-month period. RESULTS: One hundred and three participating centers collected data on 3,018 stroke cases. Stroke onset was more frequent on Mondays and between 08.00 and 10.59 h. Median time to admission after symptom onset was higher on Fridays (173.5 min) and between 20.00 and 22.59 h (207 min). Rescue by ambulance was associated with a greater stroke severity. Median time from hospital admission to brain neuroimaging investigations was higher on Saturdays (178.5 min) and between 23.00 and 10.59 h when the most severe strokes were hospitalized. CONCLUSIONS: The pattern of patient hospital referral and the time interval from stroke onset to hospital admission and brain neuroimaging investigations varied widely according to the hour and weekday of onset as well as to the reduced availability of hospital resources. An adequate distribution of the available resources should be planned in order to meet the demand.
Abstract: OBJECTIVE: To evaluate incidence, case fatalities and prognosis of subarachnoid hemorrhage (SAH). Subjects and METHODS: Prospective population-based registry (1994-1998) including patients with a first-ever stroke followed up to 10 years. RESULTS: In a 5-year period we included 118 patients (55 men and 63 women; mean age +/- SD 60.7 +/- 15.9 years) with an SAH. The crude annual incidence rate was 7.93 cases per 100,000 inhabitants (95% CI 6.46-9.63), 7.60 per 100,000 when standardized to the 2006 European population and 5.27 per 100,000 when standardized to the 2005 world population. The 7-day case-fatality rate was 16.1% (95% CI 9.5-22.7), 30-day case-fatality rate was 34.7% (95% CI 21.2-43.3), and 1-year case-fatality rate was 44.9% (95% CI 35.9-53.9). At the end of the 1-year follow-up, 53 patients (44.9%) had a good recovery [modified Rankin scale (mRS) 0-2] and 12 (10.2%) had a severe disability (mRS 3-5). The 10-year survival rate was 46.4% (95% CI 36.0-57.8). CONCLUSION: In our district, the SAH incidence rate was similar to what is reported in most European countries. Since more than half of the patients with SAH remained severely disabled or died, results from our population-based study strongly support the notion that the most appropriate treatments should be made available for all patients in comprehensive centers and the call for an urgent implementation of telemedicine in the rural areas of our district.
Abstract: Stroke is the third most common cause of death in women and a major cause of disability. Many aspects of stroke are similar in men and women, including clinical presentation, main risk factors, and distribution of the main subtypes. There are, however, some gender differences and specificities in stroke including some aspects related to treatment. Women are less likely to receive thrombolysis than men; however, in treated cases, the efficacy of intravenous thrombolysis is higher in women than in men. Hormone replacement therapy has been suggested as a possible strategy to reduce the occurrence of stroke in postmenopausal women but several clinical trials failed to show any benefit in stroke and cardiovascular disease prevention. Also in stroke prevention with antiplatelets there emerge some important gender differences: in primary prevention of stroke, aspirin was effective in women but not in men while in secondary prevention no gender differences were found with any of the available antiplatelet agents.
Abstract: Emotional lability and pathologic laughter and crying (PLC) have been frequently mentioned in patients with locked-in syndrome (LIS) without giving any detail about the clinical characteristics and possible consequences in terms of symptoms burden, functional impact, and recovery. In the present report, we describe our approach and management of 4 patients with LIS and PLC. PLC caused discomfort to the patients and hindered the different components of their rehabilitation program, limiting communication, the execution of swallowing testing and training, and the improvement of any residual motor function. PLC was unrelated to depression, did not ameliorate after pharmacologic treatment, and improved with cognitive-behavior treatment. Our findings suggest that, in LIS patients, laughter and crying alterations do not represent symptoms of a mood disorder but are the result of the same pontine lesion that causes LIS. In relation to the complex pathway regulating laughter and crying, we hypothesized that, in patients with LIS, PLC may be the result of a direct damage to the pontine center or of an alteration in the ponto-cerebellar pathway linking emotional behavior to contextual information. Presence of PLC in patients with LIS severely affects their intelligent adaptation to the environment. Direct explanation to the patients of the origin of PLC may be helpful as a cognitive-behavior treatment, with resulting benefits to the entire rehabilitation program.
Abstract: Recent studies indicate that motor imagery is subserved by activation of motor information. However, at present it is not clear whether the sparing of motor efferent pathways is necessary to perform a motor imagery task. To clarify this issue, we required patients with a selective, severe de-efferentation (locked-in syndrome, LIS) to mentally manipulate hands and three-dimensional objects. Compared with normal controls, LIS patients showed a profound impairment on a modified version of the hand-laterality task and a normal performance on mental rotation of abstract items. Moreover, LIS patients did not present visuomotor compatibility effects between anatomical side of hands and spatial location of stimuli on the computer screen. Such findings confirmed that the motor system is involved in mental simulation of action but not in mental manipulation of visual images. To explain LIS patients' inability in manipulating hand representations, we suggested that the pontine lesion, both determined a complete de-efferentation, and affected a component of the motor system, which is crucial for mental representation of body parts, probably the neural connections between parietal lobes and cerebellum.
Abstract: AIM: Electroencephalography (EEG) and somatosensory potentials (SEP) are regarded as useful tools for exploring residual brain activity and providing information for recovery in patients with anoxic encephalopaty. However, the diagnoses of vegetative and minimally conscious states can only be made by means of repeated specific neurological examinations. In this respect, this study describes the case of a patient with mismatch of neurophysiological findings despite partial recovery to a minimally conscious state. CASE REPORT: A 52-year-old man was admitted to the Post-Coma Intensive and Rehabilitation Care Unit with a diagnosis of anoxic encephalopathy. EEG, according to Hockaday, was severely abnormal (Grade IVa). SEP showed bilateral loss of all cortical components. Four weeks after admission the Coma Recovery Scale Revised (CRS-R) score moved from 7/23 to 13/23. CONCLUSIONS: This patient persistently showed a mismatch of neurophysiological findings which did not anticipate the slight but discriminating improvement ascertained through the neurological examination. This observation confirms that electrophysiological evaluations can only be regarded as ancillary tools since level of consciousness may be reliably evaluated only by means of repeated specific neurological assessments. As this case-report suggests, neurophysiological findings may turn out to be inconclusive and misleading in relation to the assessment of consciousness and may lead to an underestimate of minimal signs of recovery across the grey-zone from the vegetative to the minimally conscious state.
Abstract: Several conditions are comorbid with migraine; our review is focused on the relation between migraine, and cerebrovascular and cardiovascular diseases. Despite many studies showed an association between migraine and patent foramen ovale, it is still not known whether its presence might be causal for the migraine pathogenesis and currently its closure cannot be recommended for migraine prevention. On the contrary, conflicting epidemiological data link migraine to arterial hypertension and the use of antihypertensive agents acting on the renin-angiotensin system sounds promising in migraine prevention. A complex bidirectional relation exists between migraine and stroke, and new evidences show a clear association between migraine and coronary heart disease. In both conditions, migraine represents a defined risk factor although the magnitude of the risk varies across the different studies. However, since the risk is low in the general population, it is not possible to identify which migraineurs will develop a cardiovascular or a cerebrovascular event making difficult to apply preventive measures.
Abstract: PRIMARY OBJECTIVE: To challenge the Multi-Society Task Force's ruling that a persistent vegetative state (PVS) can be judged to be permanent for non traumatic brain injury after three months. METHOD: We report the case of a 44-year-old man who had recovery of consciousness with persistent severe disability 19 months after a non-traumatic brain injury at least in part triggered and maintained by intrathecal baclofen administration. RESULT: This unexpected and late recovery of consciousness raises an interesting hypothesis of possible effects of partially regained spinal cord outputs on reactivation of cognition. CONCLUSION: Considering that several ethical, legal, and socio-economic issues have been raised about the opportunity of withdrawing treatment and life support in patients with PVS the report of this case might add further documentation to the ongoing debate.
Abstract: BACKGROUND: Only a few non-recent studies assessed the importance of hematocrit (HCT) in patients with ischemic stroke. We evaluated how HCT might affect early mortality after stroke. METHODS: We investigated all first-ever ischemic strokes included in the population-based L'Aquila registry. 3,481 patients according to HCT (%) values were included into four categories (<or=40, 41-45, 46-50, and >50). RESULTS: There were more men than women with HCT >50 (6.6 vs. 2.8%; p < 0.0001) and more women than men with HCT <or=40 (48.5 vs. 37.9%; p < 0.0001). Proportions of chronic atrial fibrillation (p = 0.0053) increased in women from the lower to the higher HCT categories. 7- and 28-day case-fatality rates were similar in men and women in the lower HCT categories but higher in women than in men in the higher categories. At the 28-day Kaplan-Meier analysis, men had similar survivals in the different categories while women with HCT >50 showed the worst survival (p < 0.0001). At the multivariate Cox regression analysis HCT 46-50 and >50 was an independent predictor of mortality in women within 28 days. CONCLUSION: High HCT might represent in women a previously underestimated independent predictor of mortality after ischemic stroke. Consideration of HCT in future stroke trials would be useful for ameliorating stroke care, especially in women.
Abstract: OBJECTIVE: To evaluate incidence and prognosis of lacunar stroke in a prospective, population-based patient registry. METHODS: The authors included first-ever strokes occurring between 1994 and 1998. They assessed incidence, risk factors, mortality, and recurrence in patients with lacunar stroke. RESULTS: The authors identified 491 patients (15.3%) with lacunar stroke (252 men and 239 women) and 2,153 patients (67.3%) with nonlacunar stroke (998 men and 1,155 women). Crude annual incidence rate for a first-ever lacunar stroke was 33.0/100,000 (95% CI 30.2 to 36.0). At the univariate logistic regression analysis among patients with lacunar stroke there was a higher proportion of cigarette smoking and hypercholesterolemia and a lower proportion of chronic atrial fibrillation than in patients with nonlacunar stroke. For lacunar stroke, the 30-day case-fatality rate was 4.3% (95% CI 2.5 to 6.1) and the 1-year case-fatality rate was 13.0% (95% CI 10.0 to 16.0). During the first year of follow-up the average annual stroke recurrence rate was lower in patients with lacunar (2.83%; 95% CI 1.36 to 4.30) than in those with nonlacunar stroke (5.10%; 95% CI 4.17 to 6.03) while from the second year onward, rates were similar in both groups. CONCLUSION: In the short term, patients with nonlacunar stroke had more vascular events, but in the long term, the risk of death and of stroke recurrence was similar.
Abstract: The identification of comorbid disorders in migraineurs is important since it may impose therapeutic challenges and limit treatment options. Moreover, the study of comorbidity might lead to improve our knowledge about causes and consequences of migraine. Comorbid neuropathologies in migraine may involve mood disorders (depression, mania, anxiety, panic attacks), epilepsy, essential tremor, stroke, and white matter abnormalities. Particularly, a complex bidirectional relation exists between migraine and stroke, including migraine as a risk factor for cerebral ischemia, migraine caused by cerebral ischemia, migraine as a cause of stroke, migraine mimicking cerebral ischemia, migraine and cerebral ischemia sharing a common cause, and migraine associated with subclinical vascular brain lesions.
Abstract: Stroke, a disease determining an increasing socioeconomic burden in aging populations, represents the second cause of mortality worldwide and the third cause of mortality in western countries. In our study, crude annual incidence rate of stroke was 293/ 100,000. Several conditions and life-style factors have been identified as risk factors for stroke. Their recognition is important to prevent stroke. Atherothrombosis contributes a large proportion of cases; however, conventional stroke risk factors do not fully account for the risk of stroke, and often stroke victims with documented atherosclerosis may not show any conventional risk factor. A major goal is to promote prevention of stroke through identification and clarification of new risk factors and pathogenic mechanisms. Moreover, early stroke prevention requires a comprehensive multidisciplinary strategy to educate and promote adherence to preventive protocols.
Abstract: BACKGROUND AND PURPOSE: Atrial fibrillation (AF) is a major risk factor for ischemic stroke and its prevalence increases steeply with age. Population-based data on its influence on stroke outcome are scarce. METHODS: We evaluated the prevalence of AF and its influence on prognosis in patients with a first-ever ischemic stroke from a population-based registry. RESULTS: The presence of AF at stroke onset and during the acute phase was confirmed by a standard electrocardiogram in 869 (24.6%) of 3530 patients with ischemic stroke. With respect to patients without the arrhythmia, those with AF were more frequently women, aged 80 years and older, with coronary heart disease and peripheral arterial disease. The presence of AF was associated with high 30-day (32.5%; 95% CI, 29.3 to 35.6) and 1-year case-fatality rates (49.5%; 95% CI, 46.2 to 52.8), with a higher stroke recurrence rate within the first year of follow-up (6.6% versus 4.4%; P=0.046) and with the worst survival after an average follow-up of 45.2 months (P<0.0001). At the multivariate Cox regression analysis, AF was an independent predictor of 30-day and 1-year mortality. Approximately 17% of all deaths were attributable to the presence of AF. CONCLUSIONS: We found a high prevalence of AF in patients with a first-ever ischemic stroke, especially among elderly women. The overall contribution of AF to stroke mortality was relevant, suggesting that together with new strategies to prevent the development of the arrhythmia more appropriate treatments are needed, mostly in elderly women.
Abstract: OBJECTIVE: We estimated the prevalence of Parkinson's disease (PD) in the L'Aquila district. METHODS: Cases of PD were identified screening all available case sources including general practitioners and antiparkinsonian drug-users by means of pharmacy records. Prevalence of PD was computed considering the prevalence day of December 31, 2001. RESULTS: On the prevalence day, 682 patients with PD were alive and residing in the L'Aquila district. A total of 354 patients were women and 328 men. The overall crude prevalence rate was 229.3/100,000 (95% CI 212.7-247.1), without any difference between men (227.4/100,000; 95% CI 200.0-257.5) and women (231.1/100,000; 95% CI 202.2-263.1). Prevalence rates increased with age in both sexes and were higher in urban (244.5/100,000; 95% CI 213.7-278.5) than in rural residents (214.7/100,000; 95% CI 189.0-242.9) (SRR = 1.7; 95% CI 1.3-2.1). CONCLUSIONS: The prevalence of PD in the L'Aquila district was within the range of prevalence rates found in our country and steeply increased with advancing age in both sexes.
Abstract: OBJECTIVE: To evaluate the contribution of subjects 80 years old or older to the burden of ischemic stroke as compared with subjects younger than 80 years. METHODS: All first-ever ischemic strokes occurring in a 5-year period (1994 to 1998) in the population-based L'Aquila registry were traced. Incidence, total health care utilization, disability, and mortality were assessed in patients 80 years old or older, and differences with those younger than 80 years were assessed by univariate and survival analyses. RESULTS: One thousand three hundred sixteen of 3,594 first-ever ischemic strokes (36.6%) occurred in patients 80 years old or older, accounting on average for one-third of health care utilization. The crude annual incidence rate was 21.54 per 1,000 (95% CI 20.42 to 22.72). At the 1-year follow-up, 27.7% of patients had mild or no disability, 20.7% had severe disability, and 51.6% had died. With respect to patients under 80 years of age, older patients showed a higher proportion of women (61.3 vs 47.7%), atrial fibrillation (30.2 vs 20.7%), coronary heart disease (31.0 vs 23.4%), and peripheral arterial disease (14.6 vs 10.8%) and a lower proportion of cigarette smoking (15.3 vs 29.2%) and hypercholesterolemia (20.4 vs 29.4%). Thirty-day (34.6 vs 13.4%) and 1-year (51.6 vs 22.3%) mortality were higher in patients 80 years old or older than in those younger than 80, mostly in the presence of atrial fibrillation (hazard ratio [HR] was 1.39 for 30-day mortality and 1.37 for 1-year mortality) and diabetes mellitus (HR was 1.39 for 30-day mortality and 1.31 for 1-year mortality). CONCLUSION: The burden of ischemic stroke is high in subjects 80 years old or older, contributing about one-third of health care utilization and 59.8% of deaths within 30 days.
Abstract: Type 1A, the most common form of Charcot-Marie-Tooth (CMT1A) disease, is characterized by demyelination of the peripheral nervous system. So far, only a few cases of the disease with concomitant brain white matter lesions have been described. We report an Italian family with CMT1A disease, consisting of the proband and 4 affected members, presenting with concomitant brain white matter lesions at magnetic resonance imaging. The association is particularly fascinating and might depend on an autoimmune mechanism, not yet clarified.
Abstract: Intracerebral hemorrhage (ICH) occurs as a result of bleeding into the brain parenchyma and formation of a focal hematoma. Treatment for ICH is primarily supportive, and outcome remains poor. Initial management is directed toward stabilizing breathing and circulation. Increased intracranial pressure is currently managed with osmotic agents (mannitol and glycerol); steroids, hypovolemia, controlled hyperventilation, and barbiturate coma can also be employed. Arterial blood pressure control is useful and requires adequate compliance to specific guidelines. Ultra-early hemostatic therapy may represent a promising tool to reduce early hematoma enlargement and to improve outcome.
Abstract: Vasculitis is an inflammation of the vessel wall. It may be either primary or secondary. Primary vasculitis includes systemic vasculitis (large, medium, and small-vessel vasculitis) and localized vasculitis (isolated angiitis of the central nervous system and non-systemic vasculitic neuropathy). Secondary vasculitis may be present in connective tissue disorders or may be caused by infections, neoplasms, and substance abuse. Patients presenting with symptoms suggestive of vasculitis require brain neuroimaging, lumbar puncture, and angiography, but only biopsy allows a definite diagnosis.
Abstract: Mechanisms underlying the gastric toxicity of nonsteroidal anti-inflammatory drugs (NSAIDs) have been extensively investigated, whereas those leading to intestinal damage are not completely understood. Several hypotheses have been put forward on the pathophysiology of intestinal damage by NSAIDs: enhanced intestinal permeability, inhibition of cyclooxygenase (COX), enterohepatic recirculation, and formation of adducts. The effects of COX-2 selective inhibitors, which appear to have better gastric tolerability when compared to nonselective NSAIDs, on normal and inflamed intestinal mucosa (as in Crohn's disease or ulcerative colitis) are still largely unexplored. If COX-2 inhibition plays a key role in suppressing the inflammatory process, recent evidence suggests that COX-2 products are involved in maintaining the integrity of intestinal mucosa, in the healing of gastrointestinal ulcers and in the modulation of inflammatory bowel disease (IBD). Animal models of intestinal inflammation have so far yielded conflicting results on the effects of COX-2 selective inhibitors on the intestinal mucosa. It is now clear that NSAIDs do not act through cyclooxygenase inhibition, but also have different targets such as nuclear factor-kappaB and/or peroxisome proliferator-activated receptors gamma. The peculiar pharmacological profile of each compound may help to explain the different impact of each NSAID on the inflammatory process and on IBD. Notably, the salicylic acid derivative 5-ASA is widely used in the treatment of IBD and is believed to act through nuclear factor-kappaB inhibition. Although the use of COX-2 selective inhibitors remains contraindicated in patients with IBD, studying their effects on intestinal mucosa may offer new insights into their subcellulars mechanisms of action and open new avenues for the development of novel therapies for IBD.
Abstract: Stroke is the most common neurologic disease and the leading cause of adult disability in Western countries. The number of patients affected by stroke will increase by the effect of aging. Mainly due to increased life expectancy, the proportion of individuals over 65 years in the L'Aquila district showed an increase of 18.3% in a 10 years period (1981-1991). Among the resident population, in a five-year period (1994-1998) we collected all the patients with a first-ever stroke, and we found high crude and standardized (European population 1996) incidence rates. There was a significant correlation between crude and standardized incidence rates and proportion of individuals aged 65 and over, suggesting that the high incidence was due to an increased stroke risk linked to aging. As a cosequence, the number of subjects with atherosclerotic comorbidity will increase and the quality of life will worsen.
Abstract: This study evaluated the effects of two different rates of infusion of echo-contrast agents (ECA) on signal enhancement. A total of 15 patients with insufficient Doppler signal due to inadequate transtemporal acoustic bone window were examined. Signal from the middle cerebral artery was recorded during the IV infusion of Levovist (300 mg/mL). Increment of signal enhancement in dB, time to signal enhancement appearance, time to clinically useful signal enhancement appearance, and duration of clinically useful signal enhancement were assessed during two infusions at the rate of 1 and 0.66 mL/min, respectively. Increment of signal enhancement was similar at the rate of 1 and 0.66 mL/min (p = 0.4). Mean time to signal enhancement appearance and mean time to clinically useful signal enhancement appearance were not significantly different with the two rates of infusion (p = 0.9 and p = 0.3, respectively). Mean duration of clinically useful signal enhancement was significantly higher with the infusion rate of 0.66 mL/min as compared to 1 mL/min (p < 0.0001). Levovist injected at the infusion rate of 0.66 mL/min prolonged the mean duration of signal enhancement, maintaining its effectiveness.
Abstract: The aim of the study was to evaluate the diagnostic potential of galactose-based microbubble suspension (Levovist) in patients with acute cerebrovascular disease and inadequate transtemporal acoustic window, when examined by transcranial Doppler (TCD). We studied 10 patients with either transient ischemic attack (no. = 3) or stroke (no. = 7). Inadequate transtemporal acoustic window was unilateral in 3 patients and bilateral in the remaining 7 patients. Signals from middle, anterior, and posterior cerebral arteries (MCA, ACA, PCA) were recorded after injecting Levovist 300 mg/ml. Six patients needed 3 injections of Levovist, 1 patient two, and 3 patients one. Mean +/- SD duration of optimal signal enhancement was 175.2 +/- 53.2 s, range 70-290 s. Doppler waveform analysis was possible in 14 (82.3%) MCA, 11 (65%) ACA, and 9 (53%) PCA. Levovist improved the reliability of TCD in patients with acute cerebrovascular disease and insufficient transtemporal insonation.
Abstract: Spatially resolved spectroscopy (SRS) is a new near infrared spectroscopy (NIRS) method that, using the multi-distance approach, measures local cerebral cortex hemoglobin oxygen saturation [J. Matcher, P. Kirkpatrick, K. Nahid, M. Cope, and D. T. Delpy, Proc. SPIE 2389, 486-495 (1995)]. Using a conventional continuous wave NIRS photometer, cerebral venous oxygen saturation (SvO2) can be calculated from oxyhemoglobin and total hemoglobin rise induced by partial occlusion of jugular vein [C. E. Elwell, S. J. Matcher, L. Tyszczuk, J. H. Meek, and D. T. Delpy, Adv. Exp. Med. Biol. 411, 453-460 (1997)]. The aim of this study was to compare direct measurements of forehead tissue oxygenation index (TOI) with the calculated SvO2 during venous occlusion in 16 adult volunteers using a clinical two-channel SRS oximeter (NIRO-300). Measured TOI and calculated SvO2 values of either right or left forehead did not significantly differ. A good agreement between the two NIRS methods was also demonstrated. On 16 other subjects, no significant differences were found between the right and left forehead TOI values measured simultaneously, and between the TOI values measured by channel 1 or 2 on the same side. The results confirm that cerebral cortex hemoglobin oxygen saturation, measured directly by the SRS method, reflects predominantly the saturation of the intracranial venous compartment of circulation.
