Bi-hemispheric transcranial direct current stimulation for upper-limb hemiparesis in acute stroke: a randomized, double-blind, sham-controlled trial

BACKGROUND AND PURPOSE

Neuromodulation is a promising approach to increasing motor recovery in stroke; however, to date, there is a scarcity of evidence documenting the clinical potential of transcranial direct current stimulation (tDCS) administered in the acute phase of stroke. The present study aims to examine the clinical effects of a treatment involving the application of tDCS in the acute stage post-stroke.

METHODS

This was a randomized, double-blind, sham-controlled trial. A cohort of 32 stroke patients with severe motor impairment underwent 5 days of treatment with real or sham bi-hemispheric tDCS over the motor cortex. During the treatment, tDCS was applied twice per day (two daily applications each of 15 min), starting 48 to 72 h after stroke onset.

RESULTS

We found statistically significant improvements after both real and sham tDCS treatments in primary (hand grip strength, Motricity Index) and secondary (National Institutes of Health Stroke Scale score, Barthel Index) outcomes. Patients receiving real tDCS showed a larger improvement of upper-limb muscle strength at the end of treatment phase; this advantage was no longer present after 6 months.

CONCLUSIONS

Transcranial direct current stimulation may be used to accelerate the rate of upper-limb motor recovery during the spontaneous recovery period.

Medical and endovascular treatments of symptomatic intracranial stenosis. A Bayesian network meta-analysis

Intracranial stenosis is a well-established stroke risk factor with an increase of stroke recurrence or TIA up to 12.6% at 1 year. Treatments are different: medical and endovascular. We performed a multiple treatment comparison analysis to detect the best treatment in reducing the risk of stroke recurrence. We searched in Medline, Embase, Cochrane Central Register of Controlled Trials databases between 1979 and October 2017. Inclusion criteria were prospective randomized trials that evaluated patients with TIA or stroke due to intracranial stenosis and treated with different medical therapies and/or endovascular procedures. Primary endpoint was the recurrence of TIA or stroke in the territory of intracranial stenosis, while secondary endpoint was represented by any stroke or vascular death. Multiple treatment comparison meta-analysis based on a Bayesian fixed and random effects Poisson model was performed. Seven trials were included with a total of 1337 patients. At multiple treatment comparison, no significant differences between treatments were observed for both primary (median fixed effect standard OR: 0.40; 95%CI: 0.02-1.07) and secondary endpoints (median random effect standard OR: 1.17; 95%CI: 0.32-1.92). Treatment with aspirin alone ranked with high values both for primary and secondary endpoints (surface under the cumulative ranking curve of 70% and 82%, respectively). In patients with symptomatic intracranial stenosis, no differences between treatments were observed. However, aspirin alone was more effective than stenting in the reduction of TIA or stroke recurrences, with a better safety profile than oral anticoagulants.

Prehospital stroke scales and large vessel occlusion: A systematic review

BACKGROUND AND PURPOSE

Time sensitivity for pharmacological and mechanical arterial recanalization in acute ischemic stroke influences the choice of the reference hospital. The accurate selection and identification of patients with high probability of a large vessel occlusion (LVO) in the prehospital setting improve the rationalization of the transport in the more suitable centers. Aim of this analysis was to determine the diagnostic accuracy of prehospital stroke scales detecting LVO.

MATERIAL AND METHODS

Studies were searched into MEDLINE, EMBASE, and CINHAL databases between January 1990 and September 2017. Principal measurements of the meta-analysis were the overall accuracy level, sensitivity, and specificity of prehospital stroke scales.

RESULTS

Nineteen scoring systems were included in the analysis coming from 13 studies. A total of 9824 patients were considered. Although a higher heterogeneity was observed in the analysis, three scores showed better results in predicting a LVO (the stroke Vision, Aphasia, Neglect assessment, the National Institute of Health Stroke scale and the Los Angeles Motor Scale). We observed significant differences of overall accuracy only for scores including hemineglect as cortical neurological sign (P < .05).

CONCLUSIONS

This meta-analysis suggests that some prehospital scoring systems including cortical signs showed better accuracy to predict stroke due to LVO. However, the assessment of these signs could be difficult to investigate by paramedics and personnel of Emergency Medical Services, and for this reason, further prospective evaluations are needed.

HLA-DRB1*15 association with multiple sclerosis is confirmed in a multigenerational Italian family

Environmental and genetic factors seem to play a pathogenetic role in multiple sclerosis (MS). The genetic component is partly suggested by familial aggregation of cases; however, MS families with affected subjects over different generations have rarely been described. The aim of this study was to report clinical and genetic features of a multigenerational MS family and to perform a review of the literature on this topic. We describe a multigenerational Italian family with six individuals affected by MS, showing different clinical and neuroradiological findings. HLA-DRB1* typing revealed the presence of the DRB1*15:01 allele in all the MS cases and in 4/5 non-affected subjects. Reports on six multigenerational MS families have previously been published, giving similar results. The HLA-DRB1*15:01 allele was confirmed to be linked to MS disease in this family; moreover, its presence in non-affected subjects suggests the involvement of other susceptibility factors in the development and expression of the disease, in accordance with the complex disease model now attributed to MS.

Platelet Glutamate Uptake and Release in Migraine With and Without Aura

Glutamate may play an important role in the pathogenesis of migraine: glutamate release in the brain may be involved in the development of spreading depression and increased concentrations of this amino acid have been reported in plasma and platelets from migraine patients. Here we assessed platelet glutamate uptake and release in 25 patients affected by migraine with aura (MA) and 25 patients affected by migraine without aura (MoA), comparing the results with a group of 20 healthy matched controls. Both glutamate release from stimulated platelets and plasma concentrations of the amino acid were assessed by high-performance liquid chromatography, and were increased in both types of migraine, although more markedly in MA. Platelet glutamate uptake, assessed as 3H-glutamate intake, was increased in MA, while it was reduced in MoA with respect to the control group. These results support the view that MA might involve different pathophysiological mechanisms from MoA and, specifically, up-regulation of the glutamatergic metabolism. Understanding these dysfunctional pathways could lead to new, possibly more successful therapeutic approaches to the management of migraine.

Stroke care in young patients

The aims of this study were (i) to evaluate the clinical features of a consecutive series of young patients with ischemic stroke and (ii) to assess the changes in the clinical management of these patients over the study period. All consecutive cases of young adults aged 16 to 44 years, with ischemic stroke, that were admitted between 2000 and 2005 in 10 Italian hospitals were included. We retrospectively identified 324 patients. One or more vascular risk factors were present in 71.5% of the patients. With respect to the diagnostic process, an increase in the frequency of cerebral noninvasive angiographic studies and a decrease in the use of digital subtraction angiography were observed (P < 0.001 and P = 0.03, resp.). Undetermined causes decreased over 5-year period of study (P < 0.001). The diagnosis of cardioembolism increased. Thrombolysis was performed for 7.7% of the patients. PFO closure (8%) was the most frequently employed surgical procedure. In conclusion, the clinical care that is given to young patients with ischemic stroke changed over the study period. In particular, we detected an evolution in the diagnostic process and a reduction in the number of undetermined cases.

Thunderclap headache and benign angiopathy of the central nervous system: a common pathogenetic basis

Thunderclap headache (TCH) is a head pain that begins suddenly and is severe at onset; TCH might be the first sign of different neurological illnesses, and primary TCH is diagnosed when no underlying cause is discovered. Patients with TCH who have evidence of reversible, segmental, cerebral vasoconstriction of circle of Willis arteries and normal or near-normal results on cerebrospinal fluid assessment are thought to have reversible cerebral vasoconstriction syndrome (RCVS). Herein, we discuss the differential diagnosis of TCH and offer pathophysiological considerations for TCH and RCVS.

Two symptomatic cases of cluster headache associated with internal carotid artery dissection

Cluster headache is a clinical entity characterised by strictly unilateral head pain attacks accompanied by ipsilateral autonomic phenomena. We report two patients who had pain episodes mimicking cluster headache attacks, and who experienced a total or partial Horner's syndrome ipsilaterally to pain, persisting for 48 h after the last attack. A dissection of the ipsilateral internal carotid artery at the extra-intracranial passage was present in both cases. These cases highlight the need for extensive neuroradiological investigation in cluster headache patients when atypical features are present.

Migraine and cerebrovascular disease

The association between migraine and stroke is complex and bidirectional. Epidemiological studies suggest that migraine may be a risk factor for stroke; magnetic resonance studies suggest that white matter abnormalities may be more frequent in migraine patients than in controls; and stroke may occur during the course of a migraine with aura (MA) attack (migrainous stroke). However, the relationship between migraine, aura and stroke is complex and mechanisms other than a direct cause/effect relationship are possible. Migraine aura may be the consequence, rather than the cause of cerebral ischaemia. Furthermore both MA and stroke may be secondary to a third underlying condition. In this review we analyse data regarding the relationship between migraine and stroke considering 3 aspects: (1) migraine as a risk factor for stroke, (2) migraine as a cause of stroke and (3) migraine and cerebral ischaemia sharing a common cause.

Hemodynamic instability after extracranial carotid stenting

OBJECTIVE

Hemodynamic instability (hypertension, hypotension and bradycardia) is a well-known complication of carotid endarterectomy. Carotid angioplasty and stenting (CAS) is becoming a valuable alternative treatment for patients with severe carotid stenosis and increased surgical risk. CAS implies instrumentation of the carotid bulb, so baroceptor dysfunction may provoke hemodynamic instability. The aim of this work was to calculate the incidence of this complication and to detect factors to predict it.

METHODS

Medical records and angiograms of 51 consecutive patients submitted to CAS for severe atherosclerotic stenosis (40 cases) or postsurgical restenosis (11 cases) were retrospectively reviewed in order to detect the occurrence of intra- and post-procedural hypertension (systolic blood pressure >160 mmHg), hypotension (systolic blood pressure <90 mmHg) and bradycardia (heart rate <60 beats/min). The relationship between clinical, procedural and angiographic factors and the occurrence of hemodynamic instability was assessed with univariate and multivariate analysis (logistic regression).

RESULTS

Transient mild systolic post-procedural hypertension occurred in five cases (10%); preprocedural hypertension, asymptomatic stenosis and ipsilateral post-surgical restenosis predicted this. Hypotension with bradycardia also occurred in five cases (10%), one with neurological sequelae. Transient periprocedural bradycardia occurred in 19 cases (37%). Severe bradycardia without hypotension arose in one case only. Factors predicting post-procedural hypotension included the presence of a fibrous plaque and the ratio between the pre- and post-stenting diameter of the internal carotid artery. Peri-procedural bradycardia predicted post-procedural bradycardia. None of these factors were confirmed by multivariate analysis as a significant prognostic predictor.

CONCLUSION

Mild systolic hypertension may occur after CAS, but is resolved by medical treatment. Prolonged hypotension and bradycardia may also arise and this can be dangerous because it may cause neurological deterioration due to hypoperfusion. These complications cannot be predicted by clinical, procedural, and angiographic factors.

The complications of migraine with aura

Migraine with aura is a common disorder in industrialised countries, affecting up to 5% of the adult population. Although migraine aura is usually a benign disorder, in rare instances it can be the cause of serious neurologic complications. The most common is migrainous stroke, defined as a persistent neurologic deficit following the aura with evidence of brain infarction at neuroimaging and lack of alternative explanations. The most likely pathogenic mechanism is brain ischaemia induced by cortical spreading depression, but other possibilities, such as intracranic arterial dissection or embolism through patent foramen ovale need to be considered. Other complications are migraine-related seizures, which are probably caused by neuronal hyperexcitability in migraineurs, and persistent auras without infarction. These disorders are of both clinical and scientific interest, as they throw light on the complex and not yet fully understood relationship between migraine with aura, stroke and epilepsy.

Cigarette smoking and risk of cerebral sinus thrombosis in oral contraceptive users: a case-control study

Idiopathic cerebral sinus thrombosis (CST) can cause death and serious neurological disability. It is unknown whether smoking, a major risk factor for arterial stroke, is a risk factor also for CST. This work explored the association between smoking and CST in a hospital-based, multicentric, case-control study. In order to avoid the confounding effect of the different risk factors for CST, we analysed the homogeneous subgroup of oral contraceptive users. We compared the prevalence of smoking in a group of 43 young women with CST (cases), whose oral contraceptive use was the only known risk factor, with a sample of 255 healthy contraceptive users of similar age (controls). The prevalence of smoking in cases and controls was similar (26% vs. 29%). The age and geographic area-adjusted odds ratio was 0.9; 95% confidence interval, 0.4-1.8; p=0.7. Smoking in oral contraceptive users does not appear to be associated with CST.

Early invasive treatment (endarterectomy vs. stenting) of moderate-to-severe carotid stenosis in patients with transient ischaemic attack or minor stroke

Carotid endarterectomy (CA) is an effective treatment for the secondary prevention of stroke in patients with carotid stenosis >50%. More recently, carotid angioplasty with stenting (CAS) has been introduced and found to be effective in case series and small clinical trials. Although CAS has been shown not to be inferior to CA, the comparative effects of early treatment (i.e., during the first month after transient ischaemic attack (TIA) or minor stroke) with these techniques are unknown. Early treatment is advocated, as recurrent stroke tends to present frequently in this time period. On this background, we designed a randomised clinical trial comparing the efficacy and safety of CA vs. CAS in patients who had suffered TIA or minor stroke in the antecedent month. The study design and methods of this multicentre pragmatic randomised parallel-group open trial are presented here.

Controversies in optic neuritis pain diagnosis

Optic neuritis (ON) refers to any inflammatory disorder of the optic nerve. In clinical practice ON is mainly diagnosed by ophthalmologists and less frequently by neurologists. ON diagnostic criteria are included in different classification systems both in neurologic and ophthalmologic fields. Diagnosis of ON is still very unsatisfactory. Indeed diagnostic criteria are not uniform and therefore the diagnosis is still mainly formulated according to the clinical experience only. A consensus on practice guidelines for ON diagnosis might be useful. Ocular pain is a milestone in ON diagnosis, but it is too often mistreated by both the patient and the clinician. The International Headache Society (IHS) Classification of Headache Disorders provides in its 1988 and 2004 versions the diagnostic criteria for ON. These criteria are not spread and followed by the large majority of neurologists, but they are mainly applied by the experts in headache disorders. On the other hand, ON is a disorder widely encountered by neurologists and ophthalmologists. The latest IHS version defines the criteria of the pain features more precisely, but it is still unsatisfactory. In a future revision, the pain should be further detailed. Further studies aimed at validation of the diagnostic criteria of ON are strongly needed.

Atypical facial pain: clinical considerations and differential diagnosis

Atypical facial pain (ATFP), recently defined as persistent idiopathic facial pain by the revision of the Classification of the International Headache Society (IHS), is a poorly understood condition, which still lacks clear diagnostic criteria and proper treatment. The pain is described as "persistent facial pain that does not have the characteristics of cranial neuralgias and is not attributable to another disorder". In general, however, according to the IHS criteria, a diagnosis of ATFP is possible when the pain in the face is present daily and persists for most or all of the day. The pain is confined at onset to a limited area on one side of the face, often in the nasolabial fold or side of the chin and may spread to the upper or lower jaw or a wider area of the face of neck and is deep and poorly localised. It is not associated with sensory loss or other physical signs. Laboratory investigations including X-ray of face and jaws do not demonstrate relevant abnormality. Pain may be initiated by operation or injury to face, teeth or gums but persists without any demonstrable local cause. But, the definition and the diagnostic criteria are over-simplified when we face the reality of the clinical practice. Many different disorders may be included in this diagnostic category, making differential diagnosis very complex. Diagnosis of ATFP is therefore, usually, a process of elimination. A targeted history and an accurate examination are crucial to correctly classify this facial pain.

Visual evoked potentials in migraine

Migraine is a chronic disorder. Visual symptoms and hypersensitivity to light stimuli are common. The aim of this study is the analysis of visual system in migraineurs by visual evoked potentials (VEP). We studied 53 migraineurs (21 with prophylactic migraine treatment and 32 without preventive therapy) and 20 healthy control subjects. We found lower P100 latencies in migraineurs without therapy compared to controls. In treated patients, P100 latencies showed the same trend seen in the control group. We speculate a different responsiveness of the visual system in migraineurs probably due to a dysmodulation of sensor input leading to facilitation of visual processing.

Management of headache in emergency room

Headache is one of the most common symptoms that leads patients to the emergency room (ER) and is often related to diseases requiring prompt diagnosis and immediate treatment. This consideration brought us to consider the importance of the neurologist in improving the management of patients arriving in the ER with headache. We carried out a study for testing the degree of agreement between ER physician and neurologist using patient evaluation at headache centre (HC) as the gold standard. One hundred and seventeen patients with idiopathic (78) or symptomatic (39) headache were evaluated by the ER physician, the ER neurologist and the HC expert. The ER physician and the HC expert reached a fair agreement (Kappa=0.40); the other two pairs reached a moderate agreement (Kappa=0.57-0.60). There was no significant difference in the agreement of the three evaluators in patients with impairment of daily living activities or aged over 40. The agreement between the ER physician and the neurologist was lower (Kappa=0.58), especially in patients with their first headache episode. Based on our results, patients seen at the ER for a headache episode can be fairly successfully managed by the ER physician, except those who present a first attack, for whom neurological consultation is needed.

Migrainous cerebral infarction: case reports

Migraine is a common and chronic disorder. It is considered benign but several studies have suggested it as a rare risk factor for ischaemic stroke. The association is still conflicting and seems to be restricted to particular subgroups of patients (i.e., women under the age of 45, with migraine with aura, and particularly ones who smoke and use oral contraceptives). The pathogenetic mechanisms underlying this condition are not known. We describe 6 cases of migrainous stroke fully meeting the diagnostic criteria of the International Headache Society (IHS). For each patient, demographic and anamnestic data, clinical features, results of laboratory tests and neuroimaging findings were recorded. Five of the 6 cases were women (median age of 29, range from 23 to 40). The man was 36. All patients fulfilled the IHS criteria for migraine with aura. At the time of the event, 2 patients were taking oral contraceptives and smoked, one patient smoked and three patients had no vascular risk factors. The stroke manifested as homonymous hemianopia in 3 patients, lower homonymous quadrantopia in 1 patient and sensory symptom in 1 patient. The neurological examination was normal in 1 case. All patients underwent several tests with negative results: blood test (antithrombin III, protein C or S, autoantibodies), transthoracic and transoesophageal echocardiography, extracranial and intracranial Doppler sonography, and angiography which was not performed in 1 patient. All patients had a cerebral infarct visible on neuroimaging study (MRI): posterior cerebral artery in 4, middle cerebral artery in 1 and anterior cerebral artery in 1. We support the findings reported by others that migrainous stroke is more common in young women affected by migraine with aura. In consideration of the high prevalence of migraine in the population, further research is indicated and necessary to establish if migraine is independent from other vascular risk factors.

Optic neuritis: diagnostic criteria application in clinical practice

Optic neuritis (ON) refers to any inflammatory optic neuropathy. In clinical practice ON is mainly diagnosed by ophthalmologists and less frequently by neurologists. ON diagnostic criteria are included in the Classification of International Headache Society (IHS) and in other classification systems, both in neurological and ophthalmologic fields. The aims of this study were to verify the application of IHS ON diagnostic criteria in clinical practice and the role of the ocular pain qualitative aspects. We performed a partially retrospective (140 cases) and prospective (43 cases) study analysing the clinical characteristics of patients with ON. We observed retro orbital pain in a huge percentage of patients; it was provoked or spontaneous and worsened by eye movements. We found that the new IHS classification criteria (IHS 2004) do not fully satisfy the requirements for ON diagnosis. Further study is necessary to validate the diagnostic criteria of ON in clinical practice.

Does headache represent a clinical marker in early diagnosis of cerebral venous thrombosis? A prospective multicentric study

The main aim of this study is to look for early clinical markers of cerebral venous thrombosis (CVT). As headache represents the major clinical manifestation at presentation we focused our attention on this symptom. We present the preliminary results of a prospective multicentric study that includes cases diagnosed as CVT in the participating centres. We have so far studied 35 patients (5 males and 30 females) from the ages of 18 to 78. The most frequent manifestation was headache (77.1%). It was more frequently localised (66.7%) and continuous (77.8%). The onset of pain was mostly acute-subacute (38.5%-50.0%) and the intensity moderate-severe (37.0%-51.9%). On univariate analysis, we found a positive correlation between CVT, acute headache onset (p=0.001) and severe headache (p=0.004). These preliminary results seem in accordance with our previous findings in the retrospective study, suggesting that CVT is more often associated with acute-onset headache of severe intensity.

Headache in cerebral venous thrombosis

In the past, cerebral venous thrombosis (CVT) was considered a rare, devastating disease. The widespread use of angiography, magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) over the years has made early diagnosis of CVT possible and has completely changed the perception of this condition. CVT is much more common than previously thought. It has a wide spectrum of clinical presentation, multiple causes and unpredictable outcome. In contrast to arterial stroke, headache is the most frequent and, at times, the only symptom of CVT. It is crucial to recognise the association of headache with CVT in order to reach a correct diagnosis and to start the appropriate treatment as soon as possible. Therefore in order to define the headache features useful for an early diagnosis of CVT we reviewed the current literature on this topic and performed both a retrospective and a prospective study. In the literature we found that this headache has no specific features as it can be of any grade of severity and is slightly more frequently diffuse than localised. Its onset is usually subacute over a few days but it can also be acute or chronic. It is mostly persistent but can occasionally be intermittent. Headache attributed to CVT is sometimes misleading, mimicking migraine, subarachnoid haemorrhage, CSF hypertension or hypotension. However this information has been derived from case series which lacked a control group and thus have low statistical strength. Our retrospective study, confirmed by preliminary results in the prospective multicentric study, showed that headache in CVT is as often acute as subacute, and that it is more frequently localised than diffuse. Finally, both studies showed a significant correlation between headache of acute onset and severe intensity and CVT. We then conclude that these headache features, especially in the presence of underlying prothrombotic conditions, should lead clinicians to consider the diagnosis of CVT and to require appropriate neuroimaging examinations.

Migraine and stroke

The association between migraine and stroke is a dilemma for neurologists. Migraine is associated with an increased stroke risk and it is considered an independent risk factor for ischaemic stroke in a particular subgroup of patients. The pathogenesis is not known but several studies report some common biochemical mechanisms between the two diseases. A classification of migraine-related stroke that encompasses the full spectrum of the possible relationship between migraine and stroke has been proposed and it includes three main entities: coexisting stroke and migraine, stroke with clinical features of migraine, and migraine-induced stroke. The concept of migraine-induced stroke is well represented by migrainous infarction; it is described in the revised classification of the International Headache Society (IHS), and it represents the strongest demonstration of the relationship between ischaemic stroke and migraine. A very interesting common condition in stroke and migraine is patent foramen ovale (PFO) which could play a pathogenetic role in both disorders. The association between migraine and cervical artery dissection (CAD) is reported in recent studies. Migraine is more frequent in patients with CAD. This supports the hypothesis that an underlying arterial wall disease could be a predisposing condition for migraine. The neuroradiological evidence of subclinical lesions most typical in the white matter and in the posterior artery territories in patients with migraine, opens a new field of research. In conclusion the association between migraine and stroke remains conflicting. Solving the above mentioned issues is fundamental to understanding the epidemiologic, pathogenetic and clinical aspects of migraine-related stroke.

MIDAS questionnaire in the emergency setting

Migraine is a common disorder and is a major cause of disability and loss of working performance in western countries. Therefore, many tools have been developed to assess migraine related disability. Among these, the Migraine Disability Assessment (MIDAS) questionnaire has been shown to be of particular interest, as it is valid, reliable and useful for therapeutic decisions. In this pilot study, we address the validity of the MIDAS questionnaire in an unselected population of migraine patients in the emergency setting. We found that the MIDAS scores in the emergency room were similar to those collected in a specialised headache centre. This result suggests that the MIDAS questionnaire could be reliably used in the emergency setting, hence avoiding unnecessary delays in the treatment of migraine patients.

Antiepileptic drugs in the treatment of chronic headaches

In recent years, anticonvulsant drugs (AEDs) have been considered promising drugs in the prevention of migraine and other forms of headache, based on their action on the metabolism of gamma-aminobutyric acid (GABA) and glutamate. To date many AEDs are being evaluated for headache preventive treatment. The results are often encouraging even if not conclusive except for valproate, which has been extensively investigated and has been found to be effective and well tolerated in the preventive therapy of migraine. Other AEDs seem to be important in the treatment of patients with resistant headaches, with both migraine and epilepsy comorbid with mood and anxiety disorders or in neuropathic pain syndromes.

Stenting of atherosclerotic stenoses of the extracranial carotid artery

BACKGROUND

Percutaneous transluminal angioplasty (PTA) and stenting seems to be, at present, the treatment of choice for early restenosis after endarterectomy and for atherosclerotic stenoses of supra-aortic trunks near or at the ostium. In contrast, the role of PTA and stenting for treatment of symptomatic and asymptomatic atherosclerotic stenosis of carotid bifurcation is still debated.

METHODS

The present study comprises 27 consecutive cases of atherosclerotic lesions of the carotid bifurcation treated with PTA and stenting. All patients were symptomatic, except for 2 suffering from asymptomatic stenosis with contralateral carotid occlusion. There were 23 stenoses occluding 70% or more of the lumen according to the NASCET criteria and 4 mild stenoses (50-60% of the lumen) with large type C ulcers. Criteria for exclusion from surgery in these cases were aged >79 years, previous neck surgery for laryngeal cancer, carotid bifurcation at C2, association with intracranial aneurysms, occlusion of the contralateral carotid artery, and heart, lung and kidney diseases. All procedures were performed under local anaesthesia associated with mild sedation in a few cases. In all cases, self-expandable stents (Wallstent) were used. Follow-up ranged from 6 to 37 months.

FINDINGS

Transient neurological deficit occurred in 3 cases (11%). One case (3.7%) experienced a minor stroke at three months. Asymptomatic tight restenosis due to intimal hyperplasia occurred in one case (3.7%). In 8 cases (40%) of complex stenosis involving common and internal carotid arteries there was some loss of contact of the stent with the wall of the common carotid artery in the late follow-up. One case (3.7%) experienced severe and prolonged hypotension and bradycardia during the release of the stent.

INTERPRETATION

From literature data and our results it emerges that periprocedural catastrophic embolism is unlikely to occur. The best results are undoubtedly obtained when treating stenosis limited to the internal carotid artery. Nevertheless, the ideal stent to treat vessels of different calibre, as occurs at the carotid bifurcation, is not yet available. The problem of periprocedural cerebral protection has not been resolved. Reported series are heterogeneous and retrospective, and an adequate follow-up of cases is still lacking.

Electrical resistance and ion diffusion through mesothelium

(1) Since phospholipids (PHL) added on the luminal side of specimens of parietal pericardium of rabbits decrease diffusional permeability (P) to Na+, but not to Cl-, P to Rb+, a cation with hydrated radius similar to that of Cl- was measured. P(Rb+) was 13.1 (+/-1.1, S.E.)x10(-5) cm/sec and it was not decreased by PHL. This suggests that PHL decrease size of intercellular "pores" of mesothelium, and restrict diffusion of solutes with radius>0.2 nm. (2) Electrical resistance (Re) of pericardium specimens was measured without PHL, with PHL, and after mesothelium was scraped away, to obtain Re of connective tissue and, thus, to compute Re of mesothelium. Re of connective tissue was 1.0+/-0.2 Omega cm(2); Re of mesothelium was 10.1+/-0.6 and 12.3+/-0.9 Omega cm(2) without and with PHL, respectively. The fraction of electrical current carried by Na+ indicates that Na+ diffusion through mesothelium without PHL is nearly free. (3) Re of cultured mesothelial cell monolayers of rat visceral pleura was 6.1+/-0.2 Omega cm(2), i.e. smaller than that of specimen mesothelium; it did not increase with PHL. P(Na+) of cultured mesothelial cell monolayers was 20.0x10(-5) cm/sec, i.e. greater than that of specimen mesothelium.

Macromolecule transfer through mesothelium and connective tissue

Diffusional permeability (P) to inulin (P(in)), albumin (P(alb)), and dextrans [70 (P(dx 70)), 150 (P(dx 150)), 550 (P(dx 550)), and 2, 000 (P(dx 2,000))] was determined in specimens of parietal pericardium of rabbits, which may be obtained with less damage than pleura. P(in), P(alb), P(dx 70), P(dx 150), P(dx 550), and P(dx 2, 000) were 0.51 +/- 0.06 (SE), 0.18 +/- 0.03, 0.097 +/- 0.021, 0. 047 +/- 0.011, 0.025 +/- 0.004, and 0.021 +/- 0.005 x 10(-5) cm/s, respectively. P(in), P(alb), and P(dx 70) of connective tissue, obtained after removal of mesothelium from specimens, were 10.3 +/- 1.42, 2.97 +/- 0.38, and 2.31 +/- 0.16 x 10(-5) cm/s, respectively. Hence, P(in), P(alb), and P(dx 70) of mesothelium were 0.54, 0.20, and 0.10 x 10(-5) cm/s, respectively. Inulin (like small solutes) fitted the relationship P-solute radius for restricted diffusion with a 6-nm "pore" radius, whereas macromolecules were much above it. Hence, macromolecule transfer mainly occurs through "large pores" and/or transcytosis. In line with this, the addition of phospholipids on the luminal side (which decreases pore radius to approximately 1.5 nm) halved P(in) but did not change P(alb) and P(dx 70). P(in) is roughly similar in mesothelium and capillary endothelium, whereas P to macromolecules is greater in mesothelium. The albumin diffusion coefficient through connective tissue was 17% of that in water. Mesothelium provides 92% of resistance to albumin diffusion through the pericardium.

Equivalent radius of paracellular "pores" of the mesothelium

Diffusional permeability (P) to water (P(w)), Cl(-) (P(Cl(-))), and mannitol (P(man)) was determined in specimens of rabbit parietal pericardium without and with phospholipids added on the luminal side, as previously done with sucrose and Na(+). P to the above-mentioned molecules and to Na(+) (P(Na(+))) was also determined after mesothelium was scraped away from specimens. P(w), P(Cl(-)), P(Na(+)), and P(man) of connective tissue were the following (x10(-5) cm/s): 73.1 +/- 7.3 (SE), 59.5 +/- 4.5, 41.7 +/- 3.4, and 23.4 +/- 2.4, respectively. From these and corresponding data on integer pericardium, P(w), P(Cl(-)), P(Na(+)), and P(man) of mesothelium were computed. They were the following: 206, 17.9, 9.52, and 3.93, and 90.2, 14.4, 4.34, and 1.75 x 10(-5) cm/s without and with phospholipids, respectively. As previously found for P to sucrose, P to solutes is smaller in mesothelium than in connective tissue, although the latter is approximately 35-fold thicker; instead, P(w) is higher in mesothelium, suggesting marked water diffusion through cell membrane. Equivalent radius of paracellular "pores" of mesothelium was computed with two approaches, disregarding P(w). The former, a graphical analysis on a P-molecular radius diagram, yielded 6.0 and 1.7 nm without and with phospholipids, respectively. The latter, on the basis of P(man), P to sucrose, and function for restricted diffusion, yielded 7.8 and 1. 1 nm, respectively.

Identification and characterization of a new member of the gas3/PMP22 gene family in C. elegans

The Gas3/PMP22 protein family is characterized by tetraspan transmembrane proteins. The gas3/PMP22 gene is highly expressed in Schwann cells of the peripheral nervous system, and different alterations of this gene are associated with hereditary demyelinating neuropathies, such as the Charcot-Marie-Tooth type 1A, the Dejerine-Sottas syndrome and the Hereditary Liability to Pressure Palsies (HNPP).Here, we report on the identification of at least one member of the Gas3/PMP22 family in the nematode C. elegans (C01C10.1b). C01C10.1b shares 36% of identical amino acids with the human Gas3/PMP22 and is characterized by four hydrophobic putative transmembrane domains. It lacks the typical N-linked glycosylation consensus in the first extracellular loop. C01C10.1b is transcribed as an operon downstream to the gene C01C10.1a, which encodes for a putative tetraspan protein with less conserved homology with the Gas3/PMP22 family. Interestingly, C01C10.1a contains three N-glycosylation sites at the C-terminus. Both genes are expressed in different nematode developmental stages and in the adults. The characterization of one member of the gas3/PMP22 family in C. elegans gives the opportunity to use this model organism to investigate the role of gas3/PMP22 in the regulation of cell proliferation and differentiation and its relation to the hereditary neurodegenerative diseases in humans.

Rho-dependent regulation of cell spreading by the tetraspan membrane protein Gas3/PMP22

Gas3/PMP22 plays a crucial role in regulating myelin formation and maintenance, and different genetic alterations in gas3/PMP22 are responsible for a set of human peripheral neuropathies. We have previously demonstrated that Gas3/PMP22 could regulate susceptibility to apoptosis in NIH3T3 cells but not in REF 52 cells. In this report we demonstrate that when the apoptotic response triggered by gas3/PMP22 was counteracted by Bcl-2 coexpression, morphological changes were observed. Time-lapse analysis confirmed that Gas3/PMP22 can modulate cell spreading, and this effect was strengthened after inhibition of phosphoinositide 3-kinase. Using the active form of the small GTPase RhoA, we have been able to dissect the different Gas3/PMP22 biological activities. RhoA counteracted the Gas3/PMP22-dependent morphological response but was unable to neutralize the apoptotic response. Treatment of NIH3T3 cells with cytotoxic necrotizing factor 1, which activates endogenous Rho, also counteracted Gas3/PMP22-mediated cell shape and spreading changes. Treatment of REF 52 cells, which are unresponsive to Gas3/PMP22 overexpression, with the C3 exoenzyme, inhibiting Rho activity, renders REF 52 cells responsive to Gas3/PMP22 overexpression for cell shape and spreading changes. Finally, assembly of stress fibers and focal adhesions complexes, in response to lysophosphatidic acid-induced endogenous Rho activation, was impaired in Gas3/PMP22-overexpressing cells. We hypothesize that cell shape and spreading regulated by Gas3/PMP22 through the Rho GTPase might have an important role during Schwann cells differentiation and myelinization.

Chronic axonal sensory and autonomic polyneuropathy without motor involvement: a new 'chronic inflammatory neuropathy?'

We report the case of a woman with axonal sensory and autonomic neuropathy lasting several months who improved in association with steroid administration. During the course of her disease and in the follow-up, the patient underwent repeated cerebrospinal fluid (CSF) examinations, neurophysiological somatic, autonomic nervous system studies and sural nerve biopsy. Clinical and laboratory assessments demonstrated the occurrence of a monophasic, chronic sensory and autonomic neuropathy. A sural nerve biopsy suggested an axonopathy. After a progressive worsening of symptoms lasting about 6 months, steroid treatment was started and within 6 months a complete recovery, with normalization of the CSF findings, was observed. Although the 'chronic inflammatory neuropathies' are still debated entities, the features of this chronic, exclusively sensory and autonomic neuropathy are new, and the occurrence of a high protein level in the CSF, together with the favorable outcome associated with steroid treatment, suggests that our case might be another variant in this debated area.

Diffusional permeability of rabbit mesothelium

Diffusional permeability (P) to sucrose (Psuc) and Na+ (PNa+) was determined in specimens of rabbit sternal parietal pericardium, which may be obtained without stripping. Specimens were mounted in an Ussing apparatus with 3H-labeled sucrose and 22Na+ in a luminal (L) or interstitial (I) chamber. Psuc was 2.16 +/- 0.44 for L-->I and 2.63 +/- 0.45 (SE) x 10(-5) cm/s for I-->L, i.e., approximately 10 times smaller than that previously obtained in stripped specimens of pleura despite the similarity of intercellular junctions in pericardium and pleural mesothelium of various species. These findings suggest that previous Psuc was overestimated because stripping damages the mesothelium. PNa+ (x10(-5) cm/s) was 7.07 +/- 0.71 for L-->I and 7.37 +/- 0.69 x 10(-5) cm/s for I-->L. Measurements were also done with phospholipids, which are adsorbed on the luminal side of mesothelium in vivo. With phospholipids in L, Psuc was 0.75 +/- 0.10 and 0.65 +/- 0.08 and PNa+ was 3.80 +/- 0.32 and 3.76 +/- 0.15 x 10(-5) cm/s for L-->I and I-->L, respectively, i. e., smaller than without phospholipids. With phospholipids in I (where they are not adsorbed), Psuc (2.33 +/- 0.42 x 10(-5) cm/s) and PNa+ (7.01 +/- 0.45 x 10(-5) cm/s) were similar to those values without phospholipids. Hence, adsorbed phospholipids decrease P of mesothelium. If the mesothelium were scraped away from the specimen, Psuc of the connective tissue would be 13.2 +/- 0.76 x 10(-5) cm/s. Psuc of the mesothelium, computed from Psuc of the unscraped and scraped specimens, corrected for the effect of unstirred layers (2. 54 and 19.4 x 10(-5) cm/s, respectively), was 2.92 and 0.74 x 10(-5) cm/s without and with phospholipids, respectively. Hence, most of the resistance to diffusion of the pericardium is provided by the mesothelium.

Mechanical coupling and liquid exchanges in the pleural space

The pleural space provides the mechanical coupling between lung and chest wall: two views about this coupling are reported and discussed. Information on volume, composition, thickness, and pressure of the pleural liquid under physiologic conditions in a few species is provided. The Starling pressures of the parietal pleura filtering liquid into pleural space, and those of the visceral pleura absorbing liquid from the space are considered along with the permeability of the mesothelium. Information on the lymphatic drainage through the parietal pleura and on the solute-coupled liquid absorption from the pleural space under physiologic conditions and with various kinds of hydrothorax are provided.

Effect of adrenaline and alpha-agonists on net rate of liquid absorption from the pleural space of rabbits

Indirect evidence supporting a solute-coupled liquid absorption from the pleural space of rabbits has recently been provided; moreover, the beta 2-adrenoceptor agonist terbutaline has been found to increase this absorption. In this study the effect of adrenaline and alpha-adrenoceptor agonists on net rate of liquid absorption (Jnet) from albumin Ringer hydrothoraces of various sizes has been determined in anaesthetized rabbits. In hydrothoraces with adrenaline (5 x 10(-6) M) the relationship between Jnet and volume of liquid injected was displaced upwards by 0.09 ml h-1 relative to that in control hydrothoraces (P < 0.01). This displacement did not occur with lower adrenaline concentrations or after pretreatment with the beta-blocker propranolol. Hence, this increase in Jnet is mediated by stimulation of beta-receptors. It seems to be caused by an increase in solute-coupled liquid absorption, since beta-agonists inhibit lymphatic activity while, at relatively high concentrations, they may increase active transport. Conversely, the strong stimulation of lymphatic alpha-receptors that should occur with adrenaline after beta-blockade may fail to increase lymphatic drainage, because it has been shown that the increase in contraction frequency of lymphatics may be balanced by the decrease in their stroke volume. Arterial blood pressure during the hydrothoraces with adrenaline was unchanged. In hydrothoraces with the alpha 2-agonist clonidine (5 x 10(-6) M; a less potent agent than adrenaline) the slope of the relationship between Jnet and volume injected increased by 26% (P < 0.01), while its origin did not change. This increase in slope did not occur with a lower clonidine concentration or after pretreatment with the alpha-blocker phentolamine. Hence, it is caused by stimulation of alpha 2-receptors, which probably lead to an increase in lymphatic drainage related to liquid load. In hydrothoraces with the alpha 1-agonist phenylephrine (5 x 10(-6) or 10(-7) M) Jnet was simlar to control values.

Effect on phloridzin on net rate of liquid absorption from the pleural space of rabbits

Previous indirect findings have suggested the occurrence of solute-coupled liquid absorption from the pleural space, consistent with Na(+)-K(+)-ATPase on the interstitial side plus a Na(+)-H+ and CI(-)-HCO3- double exchange on the luminal side of the pleural mesothelium. To assess whether Na(+)-glucose cotransport also operates on the luminal side, the relationship between net rate of liquid absorption from the right pleural space (Jnet) and volume of liquid injected into this space (0.5, 1 or 2 ml) was determined in anaesthetized rabbits during hydrothoraces with phloridzin (10(-3)M) or with phloridzin plus 4-acetamido-4'-isothiocyanatostilbene-2, 2'-disulphonic acid (SITS; 1.5 x 10(-4)M). The relationship obtained during hydrothoraces with phloridzin was displaced downwards by 0.09 ml h-1 relative to that in control hydrothoraces (P < 0.01). The decrease in Jnet was similar in hydrothoraces of various sizes. The relationship obtained in hydrothoraces with phloridzin plus SITS was displaced downwards by 0.16 ml h-1 relative to that in control hydrothoraces (P < 0.01), i.e. the decrease in Jnet was similar to the sum (0.17 ml h-1) of the decreases in Jnet produced individually by phloridzin and by SITS (0.08 ml h-1). The decrease in Jnet was similar in hydrothoraces of differing size. The above findings are consistent with the occurrence of Na(+)-glucose cotransport on the luminal side of the pleural mesothelium, operating simultaneously with the double exchange also under physiological conditions.

cec-1, a soma-specific chromobox-containing gene in C. elegans

The chromo domain is a phylogenetically conserved sequence motif which was identified as a region of homology between the repressor protein Pc and the heterochromatin constitutive protein HP1 of Drosophila. The specific function of the chromo domain is not yet understood, but it seems to be required for protein-protein interactions in chromatin-associated complexes. Here, we present a new chromobox-containing gene from Caenorhabditis elegans (cec-1). It encodes a nuclear protein that is present in all somatic cells from the 50- to 80-cell stage on throughout development and in adult animals. No cec-1 protein was detected in the cells of early embryos, in germ cells, and in their precursor cells Z2 and Z3. cec-1 mRNA, however, is already present in all the blastomeres of early embryos. Immunolocalization experiments revealed a homogeneous distribution of CEC-1 within interphase nuclei, while during mitosis CEC-1 seems to dissociate from the condensing chromosomes. The expression pattern of the cec-1 gene suggests that it may represent a new regulatory gene in C. elegans.

Beta-agonist activation of an amiloride-insensitive transport mechanism in rabbit pleura

The beta-agonist terbutaline increases the net rate of liquid absorption from hydrothoraces with albumin-Ringer solution: since beta-agonists decrease lymphatic drainage, the effect of terbutaline seems due to an increase in solute-coupled liquid absorption, (Zocchi et al. 1994 Respir. Physiol. 97:347-356). In this research we determined in anesthetized rabbits the rate of volume change in albumin-Ringer hydrothoraces of different size with amiloride plus terbutaline, and compared it with that previously obtained in hydrothoraces with amiloride alone. The net rate of liquid absorption was 0.09 ml/h greater (P < 0.01) with amiloride plus terbutaline than with amiloride alone. This indicates that terbutaline activates an amiloride-insensitive mechanism of Na+ transport. The increase in net rate of liquid absorption produced by terbutaline persisted with bumetanide 10(-6) M and SITS 10(-4) M, disappeared almost completely with bumetanide 10(-5) M, and completely with furosemide 10(-3) M. These findings suggest that the mechanism activated by terbutaline, when the amiloride-sensitive mechanisms of the pleura have been blocked, is a Na(+)-K(+)-2 Cl- or Na(+)-Cl- symport little sensitive to bumetanide.

Effects of beta-adrenergic blockade or stimulation on net rate of hydrothorax absorption

We determined in anesthetised rabbits the net rate of liquid absorption (NRLA) from Ringer or 1% albumin-Ringer hydrothoraces with the beta-blocker propranolol (or nadolol) or the beta-agonist terbutaline. The beta-blocker reduced NRLA by 38% in 2 ml Ringer hydrothoraces, and did not change it in 2 ml albumin-Ringer hydrothoraces; hence, with beta-blocker NRLA became similar in both kinds of hydrothorax (0.31 +/- 0.02 ml/h). Terbutaline decreased NRLA by 25% in 2 ml Ringer hydrothoraces, and increased it by 29% in 2 ml albumin-Ringer hydrothoraces; hence, with terbutaline NRLA became similar in both kinds of hydrothorax (0.40 +/- 0.02 ml/h), and 25% higher than with beta-blocker. Because beta-adrenoreceptor activity inhibits lymphatic smooth muscles and may increase Na+ transport in epithelia, these results suggest that: (1) pleural mesothelium is provided with beta-receptors, which increase Na+ transport and seem activated by protein dilution, (2) beta-receptors of the pleural lymphatics are essentially silent with and without protein dilution, (3) the lymphatic drainage produced by smooth muscle activity is smaller than the increase in solute-coupled liquid absorption caused by mesothelium beta-receptors.

Active Na+ transport and coupled liquid outflow from hydrothoraces of various size

The net rate of liquid flow and Na+ flux across the pleura was determined in anesthetised rabbit during hydrothoraces 0.5 to 5 ml in size, without and with amiloride. In the hydrothoraces with amiloride the net liquid flow and Na+ flux reversed when the volume injected approached zero. This indicates that the active Na+ transport and the consequent liquid absorption occur also under physiological conditions. The difference between the data obtained without and with amiloride provides the net solute-coupled liquid outflow and active Na+ efflux. These parameters increased linearly with the hydrothorax size up to 2 ml (0.39 ml/h and 54 muEq/h, respectively), and then levelled off. The linear relationship allowed their extrapolation to physiological conditions: 0.15 ml/h (0.07 ml.h-1.kg-1) and 21 muEq/h (0.1 muEq.h-1.cm-2). The increase in these parameters with the hydrothorax size seems due to the protein dilution caused by the Ringer injection, because it did not occur if Ringer was added with albumin to keep the protein concentration in the pleural liquid similar to that under physiological conditions.

Liquid volume, Na+ and mannitol concentration in a hypertonic mannitol-Ringer hydrothorax

In anesthetised rabbits with a 2 ml hypertonic mannitol-Ringer hydrothorax in the right space 30 mM/L mannitol were required for an unchanged volume of the hydrothorax after 60 min. [Na+] in the pleural liquid 10, 30 and 60 min after this hydrothorax was 8, 7 and 5 mEq/L, respectively, lower (P less than 0.01) than the initial one and that in a Ringer-hydrothorax. This seems due to the active transport of Na+ out of the pleural space followed by little water because of the osmotic pressure exerted by mannitol. This finding provides further evidence for an active transport without using inhibitors, and implies that the mesothelium offers an appreciable resistance to small solute diffusion. Mannitol concentration, measured at corresponding times from the activity of labeled mannitol, was 76, 68 and 56%, respectively, of the initial one (24.5 mM/L). From 30 to 60 min 6.5 microM of mannitol left the right space mainly by diffusion. The diffusional permeability of the mesothelium was indirectly assessed from the diffusional outflux of mannitol, the surface of the pleural space, and an estimate of mannitol concentration in the interstitium next to the mesothelium: it is smaller than that found in vitro.

Starling forces and lymphatic drainage in pleural liquid and protein exchanges

Pleural liquid volume and protein concentration (C) were determined in rabbits 60 min after a 2 ml hydrothorax with various albumin concentrations in Ringer, homologous serum or plasma. The absorption rate of the hydrothorax decreased with the increase in colloid osmotic pressure of the pleural liquid (pi), being 0.56 +/- 0.03, 0.32 +/- 0.02 and 0.17 +/- 0.05 ml/h with Ringer, 1.1 and 3 g% albumin, respectively, and nil with 5% albumin, serum or plasma. C increased with Ringer and 1.1% albumin, did not change with 3% albumin, and decreased with 5% albumin, serum or plasma. The protein content in the pleural liquid increased with Ringer, did not change with 1.1% albumin, and decreased with the other hydrothoraces. These findings indicate that with hydrothoraces of this size: (1) the Starling forces plus the solute-coupled liquid absorption [Agostoni and Zocchi (1990) Respir. Physiol. 81: 19-28] provide most of the pleural liquid absorption when pi is less than or equal to physiological; (2) the lymphatic drainage increases with pi, providing most of the liquid outflow when pi is similar to that of plasma. This increase in lymphatic drainage, however, does not compensate for the effects of the changes in Starling forces produced by the increased pi.

Electrolyte transport across the pleura of rabbits

The amounts of Na+ and Cl- in the right pleural space of anesthetized rabbits were determined 10 and 60 min after a 2 ml hydrothorax with the following solutions: Ringer, Ringer with an inhibitor of the Na(+)-Cl- coupled transport or of the Na+/K+ pump, Ringer with gluconate instead of Cl- or with methylglucamine instead of Na+. During the 10-60 min period: (a) with Ringer Na+ and Cl- decreased (P less than 0.01) along with an iso-osmotic liquid absorption, (b) with disulfonic-stilbene (0.1 mM), amiloride (0.7 mM), acetazolamide (0.1 mM), or ouabain (0.5 mM) Na+ did not change and Cl- decreased less (P less than 0.01) than with Ringer. With gluconate-Ringer or methylglucamine-Ringer the liquid flow reversed: in the former case Cl- and, to a smaller extent, Na+ increased (P less than 0.01); in the latter only Na+ increased (P less than 0.01). These findings suggest: (1) the occurrence of a Na+/H+ and Cl-/HCO3- double exchange on the serosal side and of a Na+/K+ pump on the interstitial side of the pleural mesothelium; (2) a slow efflux from the pleural space of gluconate or methylglucamine relative to the corresponding influx of Cl- or Na+, respectively; this drags liquid into the space by osmotic gradient.

Pleural liquid pressure

The knowledge of pleural liquid pressure (Pliq) is essential for understanding the mechanical coupling between lung and chest wall and the liquid exchanges of the pleural space. In the last decade, research in this field contributed new ideas and stimulating controversies but also caused some confusion. These aspects, along with the older contributions, are considered in this review, which is divided into three sections. The topics of the first section are 1) measurements of Pliq with different techniques in various mammals and various regions of the pleural space, 2) comparison of Pliq with the pressure exerted by the lung recoil (Ppl), and 3) vertical gradient of Pliq and downward flow of pleural liquid. In the second section the mechanisms absorbing liquid from the pleural space are analyzed: 1) Starling forces of the visceral pleura, 2) lymphatic drainage through the stomata of the parietal pleura, and 3) active transport of solutes. The third section deals with 1) measurements of pleural liquid thickness with two approaches in the costal region of various mammals and 2) mechanisms preventing a complete removal of pleural liquid and, thus, ensuring the lubrication.

Solute-coupled liquid absorption from the pleural space

The occurrence of a solute-coupled absorption of liquid from the pleural space was studied by measuring in anesthetized rabbits the volume of liquid of the right pleural space 1 h after injecting into it 2 ml of Ringer solution or of Ringer with an inhibitor of a Na(+)-Cl- coupled transport or of the Na+/K+ pump. Volume collected after Ringer was 1.56 +/- 0.08 ml. Initial volume being 2.2 ml, net absorption rate was 0.64 ml/h. Volume collected after disulfonic stilbene (0.1 mM) or bumetanide (0.1 mM) was 2.01 +/- 0.06 and 2.01 +/- 0.05 ml, respectively; net absorption rate was reduced to 0.19 ml/h. This suggests the occurrence of Na(+)-Cl- coupled transports. Volume collected after ouabain (0.5 mM) was 2.08 +/- 0.08 ml; net absorption rate was reduced to 0.12 ml/h. This suggests the occurrence of the Na+/K+ pump. The marked reduction in the hydrothorax absorption produced by the inhibitors shows the occurrence of a solute-coupled liquid absorption from the pleural space. Liquid absorbed through the visceral pleura by the solute-coupled transport should be removed by the Starling forces of pulmonary capillaries. Solute-coupled absorption of liquid through the parietal pleura should oppose the filtration caused by the Starling forces.