[Irreversible bilateral amaurosis in a 36-year-old immigrant]

We report on a 36-year-old man with a history of mild head trauma. The initial clinical findings and the CT-scan of the brain revealed no pathological result, although the patient suffered from weakness of the right arm and bilateral blindness. Those findings were interpreted as psychogenic disorder. Nine days later he developed an instable gait, a child like attitude, amnesia and enuresis. The CT-scan revealed a subacute bilateral occipital stroke in the region of the arteriae cerebri posteriors. No cause for the stroke was found. In spite of the rareness of cortical blindness in young people as a cause of stroke, a detailed medical history and clinical examination should always be performed, and by unclearness additional investigations should be considered.

Schlaganfallprävention

Das Schlaganfallrisiko kann durch Änderung der Lebensgewohnheiten (Ernährung, körperliche Aktivität, Nikotinabstinenz) und die Behandlung der vaskulären Risikofaktoren deutlich reduziert werden. Eine orale Antikoagulation wird bei kardiogenen Embolien, zerebralen Venenthrombosen und beim Antiphospholipid-Antikörper-Syndrom eingesetzt. Weniger gut belegte Indikationen sind große Aortenbogenplaques, Gefäßdissektionen und symptomatische intrakranielle Gefäßstenosen. Falls keine Indikation für eine Antikoagulation besteht, werden Thrombozytenaggregationshemmer verabreicht. Dabei sind Aspirin oder die Kombination Aspirin-Dipyridamol die Therapie der Wahl. Bei Ischämierezidiven unter Aspirin, Aspirinunverträglichkeit oder Hochrisikopatienten wird Clopidogrel verwendet. Bei hochgradigen symptomatischen extrakraniellen Karotisstenosen ist die Indikation zur Karotisendarterektomie unbestritten.

Acupuncture and spinal cord medicine

BACKGROUND

The National Institutes of Health has concluded that the potential value of acupuncture justifies expanding its use into conventional medicine and studying it further.

METHODS

Literature review of acupuncture as it pertains to spinal cord medicine.

RESULTS

Acupuncture has been used to treat a number of spinal cord injury (SCI)-related conditions, including motor deficits, pain, spasticity, and syringomyelia.

CONCLUSION

Acupuncture shows promise as an intervention in the treatment of SCI-related conditions. Further research, carried out in careful and systematic fashion by qualified practitioners of acupuncture in concert with spinal cord medicine specialists, is needed.

Diffusion-weighted MRI in acute spinal cord ischaemia

Acute spinal cord ischaemia is often undetectable with conventional MRI. Diffusion-weighted MRI (DWI) has been difficult to use in the spine because of susceptibility artefacts. We assessed the diagnostic value of echoplanar DWI for early confirmation of spinal cord ischaemia. We performed conventional MRI and DWI in two men and three women, aged 54-75 years with clinically suspected acute spinal cord ischaemia. Imaging was performed 9-46 h after the onset of symptoms, and 2-9 days later to assess the extent of ischaemic signal change. Spatial resolution of DWI within the spine using standard equipment was poor, but in all patients, early DWI revealed areas of high signal indicating decreased diffusion, confirmed by measurement of apparent diffusion coefficients. Follow-up MRI showed high signal on T2-weighted images and contrast enhancement at the expected levels. Neurological deficits corresponded with radiological findings in four patients: various syndromes, including isolated bilateral weakness or sensory change and combined deficits, were found. Echoplanar DWI may be helpful for confirmation of spinal cord ischaemia in the acute stage, but follow-up T2-weighted images have superior spatial resolution and correlation with clinical findings and lesion extent.

[Health services research: subject matter and objectives of a field at the intersection of economics, medicine and ethics]

In analogy to the famous saying that war is too serious to leave it to the generals, one could say that the provision of medical care is too serious and too costly to leave it to doctors. This, however.would give the impression of an incongruity which does not exist as an actual factor or as a standpoint in research on the healthcare system. Having said that, there are differences in the methods of observation used: doctors always base their observations on their experiences at the doctor/patient level. In these situations, they are influenced by the therapeutic imperative of wanting to help and their convictions do not allow them to take into account competing requirements or to feel dependent on the higher-level conditions; and the realm of research on the health care system bases its observations more or less on findings derived by means of analysing what is often highly aggregated data, be it of a medical, economic or epidemiological nature. Even though the insights gained at the macrolevel ultimately have to be applied at the microlevel of the doctor/patient relationship, there remains an internal distance from the problems of care which is conducive to proper judgement. From this distant vantage point, researchers attempt to prove the relationship between effort and yield, to indicate weak spots which individual doctors cannot recognise and to define capacity, structure and incentive conditions which guarantee maxi-mum medical care quality. There is, for instance, evidence of astonishing dependence between the medical care provided and incentives for the number of doctor/patient contacts, use of medicines, surgery rates and number of diagnoses. This evidence can be used to draw up recommendations for self-governing bodies in the health care sector and for the political sphere as to how the health care system could be enhanced to achieve a high level of efficiency and quality.

Intra-arterial thrombolysis in 24 consecutive patients with internal carotid artery T occlusions

OBJECTIVES

To determine the safety, efficacy, and predictors of favourable outcome of intra-arterial thrombolysis in acute stroke attributable to internal carotid "T"occlusion

METHODS

The authors analysed 24 consecutive patients with T occlusions of the internal carotid artery treated by local intra-arterial thrombolysis using urokinase.

RESULTS

The median baseline National Institutes of Health Stroke Scale was 19. The average time from symptom onset to treatment was 237 minutes. Four patients (16.6%) had a favourable (modified Rankin Scale score (mRS</=2)) and 10 patients (41.7%) a poor outcome (mRS 3 or 4) after three months. Ten patients (41.7%) died. One symptomatic intracerebral haemorrhage (4.2%) occurred. Partial recanalisation of the intracranial internal carotid artery was achieved in 15 (63%), of the middle cerebral artery in four (17%), and of the anterior cerebral artery in eight patients (33%). Complete recanalisation never occurred. Sufficient leptomeningeal collaterals as seen on arteriography (p=0.02) and age <60 years (p=0.012) were the only predictors of favourable clinical outcome.

CONCLUSIONS

Acute stroke attributable to carotid T occlusion remains a condition with a generally poor prognosis even when intra-arterial thrombolysis is performed. Favourable outcome was seen only in patients with sufficient leptomeningeal collaterals.

Recanalisation of cerebral venous thrombosis

OBJECTIVE

To investigate recanalisation in the first 12 months after cerebral venous thrombosis.

METHODS

33 consecutive patients presenting with cerebral venous thrombosis were enrolled in the study. Diagnosis was made by magnetic resonance imaging (MRI) and magnetic resonance venography (MRV) or catheter angiography. Patients were initially treated with intravenous heparin. Warfarin was given for at least four months. Cerebral MRI and MRV were done at four months and repeated after 12 months if venous thrombosis persisted. Outcome was evaluated by the Rankin scale at 12 months.

RESULTS

Outcome at 12 months was good, with a median modified Rankin scale score of 0 (range 0 to 2); 27 patients (82%) had no residual deficits. No patient suffered recurrent cerebral venous thrombosis, deep vein thrombosis, or pulmonary embolism during follow up. After four months, all deep cerebral veins and cavernous sinuses, 94% of superior sagittal sinuses, 80% of straight sinuses, 73% of jugular veins, 58% of transverse sinuses, and 41% of sigmoid sinuses had recanalised. No further recanalisation was observed thereafter.

CONCLUSIONS

The results suggest that recanalisation only occurs within the first four months following cerebral venous thrombosis and not thereafter, irrespective of oral anticoagulation.

[Brief causal relations in EEG based on adaptive Granger causality]

Commonly, coherence and correlation are used to describe interrelations between EEG signals. But, on this basis, the investigation of causality or direction of interrelations is not possible. The general idea of causality between two signals may be expressed in terms of upgrading the predictability of one signal bye the knowledge of the past of the other signal. The best established approach in this context is the so-called Granger causality. The study present an adaptive estimation of Granger causality, which allows to detect dynamic causal relations within time intervals of less 100 ms. The time-variant Granger causality is applied to EEG data of the Stroop task. It could be shown, that conflict situation generates a dense web of directed interactions from posterior to anterior cortical areas.

Carotid dissection with permanent and transient occlusion or severe stenosis: Long-term outcome

OBJECTIVE

To compare the rate of ischemic events and intracranial hemorrhage in the long-term follow-up of patients with persistent and transient severe stenosis or occlusion of the internal carotid artery (ICA) due to spontaneous dissection (ICAD).

METHODS

One hundred and sixty-one consecutive patients with unilateral ICAD causing severe stenosis or occlusion were examined clinically and by ultrasound 1 year after symptom onset. Forty-six cases with persistent and 46 age- and latency-matched cases with transient (recanalization complete or less than 50% stenosis) severe stenosis or occlusion of the ICA were enrolled. Nine patients with surgical, endovascular, or fibrinolytic therapy for ICAD or associated stroke were excluded. Antithrombotic therapy was given at the discretion of the treating physician. Clinical follow-ups were done annually.

RESULTS

Antithrombotic therapy and follow-up were similar in patients with permanent (6.2 +/- 3.4 years) and transient (7.2 +/- 4.3 years) severe stenosis or occlusion of the ICA. Cases with permanent carotid stenosis or occlusion showed annual rates of 0.7% for ipsilateral carotid territory stroke and of 1.4% for any stroke. Cases with transient carotid stenosis or occlusion showed annual rates of 0.3% for ipsilateral carotid territory stroke and of 0.6% for any stroke.

CONCLUSIONS

This study suggests that ICAD has a benign long-term prognosis with low rates of ipsilateral carotid territory and any stroke and that the stroke rate in ICAD is not related to the persistence of severe carotid stenosis or occlusion. These results question the rationale of surgical or catheter-based revascularization in patients with ICAD.

[Anticoagulation and antiaggregation in neurological patients]

Aspirin is the drug of choice in most patients with acute stroke, if thrombolysis is contraindicated. Heparin is only used in acute stroke due to cerebral venous thrombosis, extracranial carotid or vertebral artery dissection and cardiac emboli with high risk of recurrence. In the prevention of recurrent stroke in patients with a noncardioembolic ischemic stroke antiplatelet agents are used. Aspirin is the first-line agent. Clopidogrel or a combination aspirin/dipyridamol are recommended for patients with several risk factors or recurrent cerebrovascular events. Warfarin has demonstrated a clear efficacy in stroke prevention in patients with atrial fibrillation, cerebral venous thrombosis and antiphospholipid antibody syndrome. Other, less well established possible indications for warfarin in the secondary prevention of stroke are symptomatic intracranial artery stenosis, large aortic atheroma, extracranial carotid or vertebral artery dissection and patent foramen ovale.

Assessing the efficacy of a ram-genotyping programme to reduce susceptibility to scrapie in Great Britain

Susceptibility to clinical scrapie is associated with polymorphisms in the PrP gene. The 'ARR' allele of this gene reduces susceptibility to clinical disease caused by all known strains of the transmissible spongiform encephalopathy (TSE) agent. The British government proposes to use a ram-genotyping scheme to breed genetic resistance to clinical scrapie into the national sheep population. We considered how best to target limited genotyping resources to achieve the maximum rate of genotype evolution. We created a metapopulation model of the British sheep industry, which includes the major pure-breeds of sheep and the cross-breeds produced by crossing these pure-bred animals. The main criterion for assessing the efficacy of different strategies was the time taken to increase the prevalence of the ARR allele in the slaughter-lamb population. Our model predicted that the most-effective strategy would be to target genotyping to those rams used for pure-breeding (i.e. mated with the same breed of ewe). This strategy was compared to two further strategies, in which the proportion of rams genotyped in each breed depended on the prevalence of the ARR/ARR genotype in that breed. A policy in which the proportion of animals genotyped is reduced as the ARR prevalence in that breed increases is efficient. The most-effective policy was targeting the hill sector in the early years and gradually switching to genotyping more terminal-sire and longwool rams as the resistance of the hill sector increases.

Apparent diffusion coefficient mapping of infarcted tissue and the ischaemic penumbra in acute stroke

MRI assessment of diffusion changes in acute cerebral ischaemia necessitates analysis of the apparent diffusion coefficient (ADC). We used the concept of relative weighted mean ADC (rwmADC) to obtain an accurate estimate of the extent of infarcted tissue. We studied ten patient with of acute ischaemic stroke, using diffusion- and perfusion- weighted MRI. The rwmADC was used to calculate a corrected ADC-lesion volume (DLVR), which was compared with the diffusion-lesion volume (DLV), initial perfusion lesion volumes and the follow-up infarct volume on T2-weighted images. We looked at correlations between the MRI and clinical findings. DLVR was closest to the final infarct size and had the best clinicoradiological correlation (r=0.77). Weighting the mean ADC within the ischaemic and normal parenchyma can give a more correct estimate of the volume of infarcted brain parenchyma, thus improving the definition of the penumbra.

[Stroke as an emergency]

Patients with acute ischemic stroke can be treated by intravenous thrombolysis within 3 hours or by intraarterial thrombolysis within 6 hours of symptom onset. Thrombolysis leads to an absolute reduction of a long term disability of 11-15% in selected patients. Aspirin is the drug of choice in most patients with acute stroke, if thrombolysis is contraindicated. Heparin is only used in acute stroke patients with high risk of recurrence. The diagnosis and treatment of medical and neurological complications remain crucial in the management of acute stroke.