Fast or Slow? A Comparison Between Two Transcranial Electrical Stimulation Techniques for Eliciting Motor-Evoked Potentials During Supratentorial Surgery.

PURPOSE: During intraoperative neurophysiological monitoring of motor pathways, two types of transcranial electrical stimulation are available, i.e., constant-current and constant-voltage stimulation. Few previous studies, performed only during spinal surgery, analyzed and compared them during intraoperative neurophysiological monitoring. The aim of our study was to compare these two stimulation techniques for eliciting motor-evoked potentials during intraoperative neurophysiological monitoring in a group of patients affected by supratentorial lesions. METHODS: Supratentorial lesions from 16 patients were retrospectively collected and analyzed. Motor-evoked potentials were performed only from transcranial electrical stimulation because the inability to place the subdural strip electrodes correctly did not permit to perform direct cortical stimulation. At the beginning of surgery, in each patient, motor-evoked potentials were monitored by using both "fast-charge" constant-voltage and "slow-charge" constant-current stimulation. Several neurophysiological parameters were collected and compared between the two stimulation techniques by means of statistical analysis. RESULTS: "Fast-charge" constant-voltage stimulation allowed statistically higher efficiency rates for eliciting motor-evoked potentials compared with "slow-charge" constant-current stimulation, both for upper and lower limbs. We also found that threshold and maximal charge as well as charge density were significantly lower during constant-voltage stimulation, thus lowering the potential tissue damage. CONCLUSIONS: "Fast-charge" constant-voltage transcranial electrical stimulation is feasible and safe during intraoperative neurophysiological monitoring for supratentorial surgery and may be preferable to "slow-charge" constant-current stimulation.

Posterior Reversible Encephalopathy Syndrome in Guillain-Barré Syndrome: Just a Problem of Immunoglobulins? Controversy From Two Atypical Case Reports.

Background: Posterior reversible encephalopathy syndrome (PRES), reversible cerebral vasoconstriction syndrome (RCVS), or the coexistence of these two entities shares similar risk factors and clinical features. For these conditions, a common origin has been supposed. Even if the majority of patients show a favorable course and a good prognosis, a small percentage of cases develop neurological complications. Up to date, only about 30 cases of PRES associated with Guillain-Barré syndrome (GBS) have been reported in the literature. Cases: Here, we present two cases of a particularly aggressive PRES/RCVS overlap syndrome, associated with acute motor axonal neuropathy (AMAN) and acute inflammatory demyelinating polyneuropathy (AIDP) variants of GBS, respectively, presenting with similar initial clinical aspects and developing both an atypical and unfavorable outcome. On MRI examination, the first patient showed typical aspects of PRES, while, in the second case, radiological features were atypical and characterized by diffusion restriction on the apparent diffusion coefficient (ADC) map. The first patient demonstrated rapid worsening of clinical conditions until death; the second one manifested and maintained neurological deficits with a permanent disability. Conclusions: We suggest that PRES may conceal RCVS aspects, especially in most severe cases or when associated with a dysimmune syndrome in which autoimmune system and endothelial dysfunction probably play a prominent role in the pathogenesis. Although the role of IVIg treatment in the pathogenesis of PRES has been proposed, we suggest that GBS itself should be considered an independent risk factor in developing PRES.

Identification of stroke etiology may contribute to improve the outcome in dedicated units.

BACKGROUND: The purpose of our study is to investigate whether stroke unit (SU) care and the utilization of Trial of ORG 10172 in Acute Stroke Treatment (TOAST) criteria may contribute to reduce death and disability in hospitalized patients after a first-ever ischemic stroke (IS). METHODS: Data included in the present study were derived from our previous study on the incidence and outcome of cerebrovascular diseases in the district of Udine, performed from April 1, 2007, to March 31, 2009. RESULTS: We identified 429 hospitalized first-ever IS cases, 297 of 429 (69.2%) patients were admitted to a dedicated SU and 132 of 429 (30.8%) to a general medical ward. According to the TOAST criteria, 101 of 132 first-ever ISs (76.5%) admitted to general medical wards were of undetermined (UND) etiology, whereas in only 105 of 297 (35.4%) patients admitted to the SU, the diagnosis remained UND. Multivariable analysis after propensity score matching showed that compared with general medical wards, SU care was associated with a reduced probability of being dead or highly disabled (P = .025) at the end of follow-up. Moreover, patients with an UND diagnosis had a worse 6-month case fatality (P < .0001) and also higher risk of being dead or highly disabled (P < .0001). CONCLUSIONS: Our study provides real-world evidence that accurate etiologic subtype classification of ISs according to TOAST criteria and SU care as opposed to general medical ward management are associated with reduction of the proportion of poor outcomes in first-ever IS patients.