Werner H. Mess

Cerebral hyperperfusion syndrome

Cerebral hyperperfusion syndrome (CHS) after carotid endarterectomy is characterised by ipsilateral headache, hypertension, seizures, and focal neurological deficits. If not treated properly it can result in severe brain oedema, intracerebral or subarachnoid haemorrhage, and death. Knowledge of CHS among physicians is limited. Most studies report incidences of CHS of 0-3% after carotid endarterectomy. CHS is most common in patients with increases of more than 100% in perfusion compared with baseline after carotid endarterectomy and is rare in patients with increases in perfusion less than 100% compared with baseline. The most important risk factors in CHS are diminished cerebrovascular reserve, postoperative hypertension, and hyperperfusion lasting more than several hours after carotid endarterectomy. Impaired autoregulation as a result of endothelial dysfunction mediated by generation of free oxygen radicals is implicated in the pathogenesis of CHS. Treatment strategies are directed towards regulation of blood pressure and limitation of rises in cerebral perfusion. Complete recovery happens in mild cases, but disability and death can occur in more severe cases. More information about CHS and early institution of adequate treatment are of paramount importance in order to prevent these potentially severe complications.

Noninvasive detection of plaque instability with use of radiolabeled annexin A5 in patients with carotid-artery atherosclerosis.

To the Editor: Although progressive stenosis of the arterial lumen constitutes the basis for ischemic symptoms in atherosclerotic vascular disease, acute vascular events are for the most part assoc...

Somatosensory cortex responses to median nerve stimulation: fMRI effects of current amplitude and selective attention

OBJECTIVES The aim of this study was to localize and to investigate response properties of the primary (SI) and the secondary (SII) somatosensory cortex upon median nerve electrical stimulation. METHODS Functional magnetic resonance imaging (fMRI) was used to quantify brain activation under different paradigms using electrical median nerve stimulation in healthy right-handed volunteers. In total 11 subjects were studied using two different stimulus current values in the right hand: at motor threshold (I(max)) and at I(min) (1/2 I(max)). In 7 of these 11 subjects a parametric study was then conducted using 4 stimulus intensities (6/6, 5/6, 4/6 and 3/6 I(max)). Finally, in 10 subjects an attention paradigm in which they had to perform a counting task during stimulation with I(min) was done. RESULTS SI activation increased with current amplitude. SI did not show significant activation during stimulation at I(min). SII activation did not depend on current amplitude. Also the posterior parietal cortex appeared to be activated at I(min). The I(min) response in SII significantly increased by selective attention compared to I(min) without attention. At I(max) significant SI activity was observed only in the contralateral hemisphere, the ipsilateral cerebellum, while other areas possibly showed bilateral activation. CONCLUSIONS Distributed activation in the human somatosensory cortical system due to median nerve stimulation was observed using fMRI. SI, in contrast to SII, appears to be exclusively activated on the contralateral side of the stimulated hand at I(max), in agreement with the concept of SIs important role in processing of proprioceptive input. Only SII remains significantly activated in case of lower current values, which are likely to exclusively stimulate the sensible fibres mediating cutaneous receptor input. Selective attention only enhances SII activity, indicating a higher-order role for SII in the processing of somatosensory input.

Diagnostic Value of 123I-Ioflupane and 123I-Iodobenzamide SPECT Scans in 248 Patients with Parkinsonian Syndromes

Background: SPECT is one of the most employed techniques in the diagnostic workup of idiopathic Parkinson’s disease (IPD). Despite its widespread use, the exact diagnostic accuracy of this technique in parkinsonian syndromes remains controversial. Methods: In this study, we investigated the diagnostic accuracy of an initial 123I-ioflupane (FP-CIT) and/or 123I-iodobenzamide (IBZM) SPECT to differentiate between IPD and other parkinsonian disorders. 248 patients underwent a SPECT scan because of an as yet unclassified parkinsonian syndrome in our clinic between 2001 and 2006. Gold standard was the clinical diagnosis derived from the latest available clinical record, or, when this was not possible, a new complete physical and neurological examination by a blinded movement disorder specialist neurologist. Mean follow-up between SPECT and the latest clinical information was 18 months (range 3 months to 5 years). Results: 223 of the 248 patients were clinically definitely diagnosed after follow-up: IPD 127, atypical parkinsonian syndromes (APS) 27, essential tremor (ET) 22, vascular parkinsonism (VP) 16, drug-induced parkinsonism (DIP) 5, doubt between PD and APS 2, other diseases without dopaminergic involvement 24. The mean odds ratio (95% CI) for FP-CIT SPECT’s ability to distinguish between IPD and ET was 82 (11–674); between IPD and VP 61 (8–490); between IPD and DIP 36 (2–697) and between IPD and APS was 1 (0–4). The odds ratio for the IBZM SPECT tracer to differentiate between IPD and APS was 7 (2–17). Conclusions: FP-CIT SPECT is accurate to differentiate patients with IPD from those with ET, and IPD from VP and DIP. The accuracy of both FP-CIT and IBZM SPECT scans to differentiate between IPD and APS is low.

Assessment of spinal cord integrity during thoracoabdominal aortic aneurysm repair

BACKGROUND Monitoring motor-evoked potentials (MEPs) is an accurate technique to assess spinal cord integrity during thoracoabdominal aortic aneurysm (TAAA) repair, guiding surgical strategies to prevent paraplegia. METHODS In 210 consecutive patients with type I (n = 75), type II (n = 103), and type III (n = 32) TAAA surgical repair was performed using left heart bypass, cerebrospinal fluid drainage, and MEPs monitoring. RESULTS Reliable MEPs were registered in all patients. The median total number of patent intercostal and lumbar arteries was five. After proximal aortic crossclamping, MEP decreased below 25% of base line in 72 patients (34%) indicating critical spinal cord ischemia, which could be corrected by increasing distal aortic pressure. By using sequential clamping it appeared that in 43% of type I and II cases spinal cord circulation was supplied between T5 and L1, and 57% between L1 and L5. In type II and III cases cord perfusion was dependent upon lower lumbar arteries in 16% and pelvic circulation in 8%, necessitating reattachment of these segmental arteries. In 9% of patients critical ischemic MEP changes occurred without visible arteries, requiring aortic endarterectomy and selective grafting. One patient suffered early paraplegia and 2 delayed, and 2 patients had temporary neurologic deficit (5 of 210; 2.4%). CONCLUSIONS In patients with TAAA, blood supply to the spinal cord depends upon a highly variable collateral system. Monitoring MEPs is an accurate technique for detecting cord ischemia, guiding surgical tactics to reduce neurologic deficit (2.4%).

High resolution sonography in the evaluation of the peripheral nervous system in polyneuropathy – a review of the literature

Clinical, laboratory and electrodiagnostic studies are the mainstay in the diagnosis of polyneuropathy. An accurate etiological diagnosis is of paramount importance to provide the appropriate treatment, prognosis and genetic counselling. High resolution sonography of the peripheral nervous system allows nerves to be readily visualized and to assess their morphology. Ultrasonography has brought pathophysiological insights and substantially added to diagnostic accuracy and treatment decisions amongst mononeuropathies. In this study the literature on its clinical application in polyneuropathy is reviewed. Several polyneuropathies have been studied by means of ultrasound: Charcot–Marie–Tooth, hereditary neuropathy with liability to pressure palsies, chronic inflammatory demyelinating polyneuropathy, Guillain‐Barré syndrome, multifocal motor neuropathy, paraneoplastic polyneuropathy, leprosy and diabetic neuropathy. The most prominent reported pathological changes were nerve enlargement, increased hypo‐echogenicity and increased intraneural vascularization. Sonography revealed intriguingly different patterns of nerve enlargement between inflammatory neuropathies and axonal and inherited polyneuropathies. However, many studies concerned case reports or case series and showed methodological shortcomings. Further prospective studies with standardized protocols for nerve sonography and clinical and electrodiagnostic testing are needed to determine the role of nerve sonography in inherited and acquired polyneuropathies.

Transcranial measurement of cerebral microembolic signals during endocardial pulmonary vein isolation: Comparison of three different ablation techniques

Introduction: Isolation of the pulmonary veins (PVI) using high ablation energy is an effective treatment for atrial fibrillation (AF) with a success rate of 50–95%; however, postoperative neurological complications still occur in 0.5–10%. In this study the incidence of cerebral microembolic signals (MES) as a risk factor for neurological complications is examined during 3 percutaneous endocardial ablation procedure strategies: segmental PVI using a conventional radiofrequency (RF) ablation catheter, segmental PVI using an irrigated RF tip catheter, and circumferential PVI with a cryoballoon catheter (CB).

Magnetic resonance angiography of collateral blood supply to spinal cord in thoracic and thoracoabdominal aortic aneurysm patients

OBJECTIVE Preservation of spinal cord blood supply during descending thoracic (TAA) and thoracoabdominal aortic aneurysm (TAAA) surgery is mandatory to prevent neurologic complications. Although collateral arteries have been identified occasionally and are considered crucial for maintaining spinal cord function in the individual patient, their critical functionality is poorly understood and very little experience exists with visualization. This study investigated whether the preoperative and postoperative presence or absence of collateral arteries detected by magnetic resonance angiography (MRA) is related to spinal cord function during the intraoperative exclusion of the segmental supply to the Adamkiewicz artery. METHODS Spinal cord MRA was used to localize the Adamkiewicz artery and its segmental supplier in 85 patients scheduled for open elective surgery for TAA or TAAA. The segmental artery to the Adamkiewicz artery was inside the cross-clamped aortic area in 55 patients, and spinal cord supply was consequently dependent on collateral supply. In these 55 patients the presence of collaterals originating from arteries outside the cross-clamped aortic segment was related to changes in the intraoperative motor-evoked potentials (MEPs) that occurred before corrective measures. Twenty-one patients returned for postoperative MRA. RESULTS A highly significant (P < .0015) relation was found between the presence of collaterals and intraoperative spinal cord function. In 30 of 31 patients (97%) in whom collaterals were identified, MEPs remained stable. The collaterals in most patients originated caudally to the distal clamp (eg, from the pelvic arteries), which were perfused by means of extracorporeal circulation during cross-clamping. The MEPs declined in 9 of 24 patients (38%) in whom no collaterals were preoperatively visualized. Postoperatively, the 21 patients who had MRA, including 10 in whom preoperatively no collaterals were found, displayed a well-developed collateral network. CONCLUSION Collateral arteries supplying the spinal cord can be systematically visualized using MRA. Spinal cord blood supply during open aortic surgery may crucially depend on collateral arteries. Preoperatively identified collateral supply was 97% predictive for stable intraoperative spinal cord function. Patients in whom no collaterals can be depicted preoperatively are at increased risk for spinal cord dysfunction.

The role of evoked potential monitoring in operative management of type I and type II thoracoabdominal aortic aneurysms

Spinal cord ischemia with subsequent paraplegia remains the most dreaded and impressive complication following thoracoabdominal aortic aneurysm repair. Protective measures, such as cerebrospinal fluid drainage, distal aortic perfusion, and epidural cooling, have significantly reduced paraplegia rate. A major impediment is the inability to assess the efficacy of reattaching intercostal arteries or the contributing value of the adjunctive procedures during the operation. Monitoring motor-evoked potentials is a reliable technique to assess spinal cord integrity, dictating surgical strategies to restore and maintain blood supply to the gray matter. Based on motor-evoked potentials, hemodynamic and operative maneuvers during thoracoabdominal aortic aneurysm repair resulted, in our experience, in prevention of neurologic deficit in 98% of patients.

Is there a side predilection for cerebrovascular disease

Abstract—In studies on carotid artery intima-media thickness and stroke, researchers implicitly assume that cerebrovascular abnormalities show a symmetrical distribution. To evaluate whether there is a difference in intima-media thickness between the 2 carotids, we compared left and right common carotid artery intima-media thickness as measured by B-mode ultrasonography in a group of 102 untreated hypertensive patients. This yielded a significant difference between both sides (left, 0.75±0.11 mm; right, 0.71±0.11 mm; P <0.001). This was associated with a higher cross-sectional area of the intima-media complex and a higher flow velocity at the left side. Arterial diameters, however, were not different. We also assessed whether there is a side preference with respect to cerebrovascular accidents. To this end, we explored our population-based Stroke Registry of 1843 subjects and indeed found a significantly higher incidence of nonlacunar cerebrovascular stroke at the left side, whereas lacunar infarcts were symmetrically distributed. Our findings suggest a predilection for cerebrovascular disease at the left side, which may be related to greater hemodynamic stress and intimal damage in the left carotid artery.