S. Pro

Saliva and serum levetiracetam concentrations in patients with epilepsy

Abstract: Although antiepileptic drug (AED) monitoring in saliva may have some clinical applicability, it has not yet come into routine use. The correlation between levetiracetam (LEV) saliva and serum concentrations also remains unclear. To confirm LEV saliva assay as a useful, noninvasive alternative to serum measurement, we investigated the possible correlation between saliva and serum LEV concentrations. Samples of saliva and blood were collected from 30 patients with epilepsy receiving chronic therapy with LEV as monotherapy or add-on therapy, and LEV concentrations were assayed in saliva and serum. Linear regression analyses showed a close correlation between saliva and serum LEV concentrations (r2 = 0.90; P < 0.001). LEV blood and saliva concentrations were linearly related to daily drug doses (r2 = 0.78 and 0.70; P < 0.01). When data were analyzed for subgroups (patients receiving LEV in monotherapy, as add-on therapy with enzyme-inducer AEDs, and as add-on therapy with noninducer or moderate-inducer AEDs), no significant difference was found between saliva and serum LEV concentrations among groups. These preliminary results indicate that LEV, like other AEDs, can be measured in saliva as an alternative to blood-based assays. Saliva LEV collection and assay is a valid noninvasive, more convenient alternative to serum measurement.

EEG mean frequency changes in healthy subjects during prefrontal transcranial direct current stimulation

In this pilot study we evaluated electroencephalographic (EEG) mean frequency changes induced by prefrontal transcranial direct current stimulation (tDCS) and investigated whether they depended on tDCS electrode montage. Eight healthy volunteers underwent tDCS for 15 min during EEG recording. They completed six tDCS sessions, 1 wk apart, testing left and right direct current (DC) dipole directions with six different montages: four unipolar montages (one electrode on a prefrontal area, the other on the opposite wrist) and two bipolar montages (both electrodes on prefrontal areas), and a single sham session. EEG power spectra were assessed from four 1-min EEG epochs, before, during, and after tDCS. During tDCS the outcome variable, brain rate (fb), changed significantly, and the changes persisted for minutes after tDCS ended. With the DC dipole directed to the left (anode on the left prefrontal area or wrist), fb increased, and with the DC dipole directed to the right (anode on the right prefrontal area or wrist), fb decreased, suggesting asymmetric prefrontal cortex functional organization in the normal human brain. Anodal and cathodal effects were opposite but equally large. Gender left these effects unchanged.

Transcranial Doppler for brain death after decompressive craniectomy: persistence of cerebral blood flow with flat EEG

Dear Editor, Brain death (BD) diagnosis is made based upon clinical criteria—unresponsive coma with absence of brainstem reflexes and persistent apnea—and upon neurophysiologic observation of persistent ‘‘flat EEG.’’ Cerebral circulatory arrest (CCA) must also be assessed with ‘‘ancillary tests,’’ e.g. conventional angiography, transcranial Doppler (TCD), and other neuroimaging techniques, in infants younger than 12 months, when EEG flattening may be related to sedative treatment, and in BD of uncertain origin [1]. CCA may indeed happen both when intracranial pressure (ICP) overrides mean arterial blood pressure (MAP) as well as in diseases affecting cerebral tissue at a cellular level, with ICP not exceeding MAP. TCD is a sensitive, specific, and noninvasive technique to detect CCA in BD by identifying specific patterns [2]. However, it may lead to false-negative results in cases of skull defects (decompressive craniectomy, external drains, and in infants), because in these cases the increase in ICP may partially be compensated for. For these reasons, we recently described the TCD modifications of the CCA patterns in infants with BD, confirming that CCA detection for BD confirmation should be done cautiously in these cases [3]. Here we describe the different TCD findings observed in two adults with BD who were subjected to decompressive craniectomy. Case 1 was a female, 62 years old, with intracerebral right temporo-parietal hemorrhage, middle cerebral artery aneurism rupture. She underwent large right frontotemporal craniectomy and presented with unresponsive coma and flat EEG (Fig. 1). TCD, performed under stable hemodynamic conditions (BP 140/70 mmHg), showed the typical CCA pattern. Short compression of the dural expansion induced a further reduction of the signal, promptly returning to the basal conditions at the end of compression (Fig. 1). Case 2 was female, 56 years old, with a small deep right basal ganglia hemorrhage and aneurysm of the right intracranial internal carotid artery. She was treated with an endovascular procedure. Following sedation withdrawal, 2 days after the procedure, she was conscious but agitated and uncooperative, and she was again sedated. TCD performed under stable hemodynamic conditions (BP 150/ 100 mmHg) (Fig. 2a) showed a very high-resistive pattern with diastolic reduction in both the middle cerebral arteries and expression of elevated ICP, confirmed by invasive

Luminance and chromatic visual evoked potentials in type I and type II diabetes: relationships with peripheral neuropathy

The objective of the study was to investigate the subclinical visual deficit in type I and II diabetes, and its relationship with peripheral neuropathy. Thirty-two healthy volunteers, 20 patients with type I diabetes and 30 patients with type II diabetes were studied in a clinical neurophysiology setting. Luminance (VEPs) and chromatic visual evoked potentials (CVEPs) were recorded, with white-black, grey-black, red-green and blue-yellow sinusoidal gratings. The peak latencies of the VEP positive wave and CVEP negative wave were recorded. Ten patients with type I and 8 with type II diabetes had peripheral neuropathy. VEPs were slower in patients with type II diabetes and CVEPs were slower in patients with type I and type II diabetes than in controls. Blue-yellow CVEPs were slower in type II than in type I diabetes. VEPs and red-green CVEPs were slower in patients with diabetes with neuropathy than in those without. In conclusion, we found that visual system impairment differs in diabetes with and without peripheral neuropathy.

Vep latency: Sex and head size

OBJECTIVE To investigate whether differences in visual evoked potential (VEP) latencies in a large sample of healthy subjects are influenced by different head size or sex or both. METHODS Black-and-white pattern-reversal checkerboard VEPs at a frequency of 2c/deg. were recorded in a group of 54 normal subjects of both sexes (age 30.15+/-9.12 years). P100 latency was measured in all subjects and the data were analyzed in the whole sample and in a selected subgroup of subjects of both sexes with comparable head size. RESULTS In the study group overall, the P100 latency was slightly shorter in females than males and this small difference reached only weak statistical significance (P<0.04) whereas head size differed significantly between sexes (females<males) (P<0.001). No difference was found in the P100 latency in the subgroup of the two sexes with a comparable range of head size. CONCLUSIONS These findings suggest that VEP latency is relatively constant in a sample of healthy subjects. The slight sex difference in P100 latencies observed in a normal sample is mainly related to the slightly smaller average head size in females than in males. SIGNIFICANCE Head size, not sex, should be considered for VEP latency normative studies.

Idiopathic late-onset absence status epilepticus: A case report with an electroclinical 14 years follow-up

Late-onset absence status epilepticus (ASE) may be observed in adult and elderly patients as a late complication of idiopathic generalized epilepsy or de novo, usually related to benzodiazepines withdrawal, alcohol intoxication or psychotropic drugs initiation, but without history of epilepsy. EEG may be highly heterogeneous, varying from the 3 to 3.5 Hz spike-wave discharges typical of idiopathic generalized epilepsy to asymmetric irregular sharp and slow wave complexes. We report the clinical and neurophysiologic 14 years follow-up of a now 86 years-old woman, in whom we observed--at the age of 72--an idiopathic late-onset ASE, with a good clinical response to lamotrigine monotherapy, but with the persistence over years of the same interictal 3-3.5 Hz spike-wave epileptic activity at EEG. This case is singular because, with the available long follow-up, indicates that idiopathic generalized epilepsy may also occur in the elderly, with a late-onset ASE presentation. In this condition, it is particularly important to underline the essential role of EEG (urgent and ambulatory) for the diagnosis, management and monitoring of the disease.

Reversible encephalopathy induced by cefoperazone: a case report monitored with EEG

In patients with an impaired state of consciousness, EEG is fundamental, a correct neurological work-up. Cephalosporins have been identified as a case of triphasic waves’ (TW) reversible encephalopathy. We report a case of an acute reversible encephalopathy with TWs during treatment with cefoperazone. We report the occurrence and regression of a confusional state with TWs encephalopathy at EEG after the administration of cefoperazone for urinary tract infection in a patient admitted for syncope. In conclusion, cefoperazone should be considered as a cause of toxic encephalopathy with EEG TWs, when there is a temporal relationship with its administration; EEG monitoring is useful in the neurological follow-up.

Non-convulsive status epilepticus characterised exclusively by a language disorder induced by non-ketotic hyperglycaemia

Non-ketotic hyperglycaemia is an endocrine emergency characterised by elevated blood glucose levels and high plasma osmolarity. While hypoglycaemia-induced seizures are usually generalised, hyperglycaemia-induced seizures are often focal and secondary to the presence of brain lesions. Moreover, in the few studies in which language disorders of epileptic origin have been reported as a clinical manifestation of non-ketotic hyperglycaemia, the disorders were usually not isolated but were followed by partial motor seizures. We describe a patient who presented with non-convulsive partial status epilepticus and whose only sign was a fluctuating language disorder induced by non-ketotic hyperglycaemia. There were no accompanying brain lesions and the patient responded optimally to diazepam. Neurophysiological EEG evaluation was fundamental for the diagnosis.

Advantages and Pitfalls of Three-Dimensional Ultrasound Imaging of Carotid Bifurcation

Objectives: Several specialists use three-dimensional (3D) ultrasound as adjuvant imaging technique in their clinical practice. It has been applied to study carotid plaque morphology, surface and volume during atherosclerosis progression. Nonetheless, no papers have so far described the use of this technique in conditions different than carotid stenosis, such as bifurcation anatomy changes of the caliber and vessel course modifications. Methods: Patients admitted to our ultrasound laboratory for vascular screening were submitted to standard carotid duplex and to 3D ultrasound reconstruction of the carotid bifurcation. Results: Forty normal subjects, 7 patients with caliber alterations (4 carotid bulb ectasia and 3 internal carotid lumen narrowing), 45 patients with course variations (tortuosities and kinking) and 35 patients with internal carotid artery stenosis of various degrees have been investigated. Conclusions: 3D ultrasound is a feasible technique. It can improve carotid axis imaging through a better presentation of caliber variations and vessel course ‘at a glance’. 3D ultrasound from the inward flow can provide imaging of the stenosis, but stenosis quantification should always take into account the assessment of plaque morphology and vessel wall.

Combined Transcranial Doppler and EEG Recording in Vasovagal Syncope

Background: In neurally mediated syncope a ‘typical’ EEG pattern during hyperventilation (HV) may be observed. This study aimed to investigate transcranial Doppler (TCD) and EEG variations in response to hyper- and hypocapnia using simultaneous recording. Methods: Syncope patients with a typical EEG pattern during HV (SEEG+, n = 15) and those without abnormalities (SEEG–, n = 16) were compared with healthy controls (n = 20). Simultaneous TCD and EEG recordings were performed at rest (baseline), during 2 apnea tests and during HV. Cerebrovascular vasoreactivity, index for hypocapnia, total vasomotor reserve and time to flow velocity normalization after HV (t-norm) were recorded. Results: With TCD, a reduction in Vasomotor reserve was observed in SEEG+ compared with the other 2 groups (control: 67 ± 8%; SEEG–: 67 ± 10%; SEEG+: 57 ± 8%; p < 0.0001). t-norm was longer in all syncopal patients and in particular in SEEG+ (control: 20.2 ± 3 s; SEEG–: 40 ± 7 s; SEEG+: 123 ± 45s; p < 0.0001). Quantitative EEG showed an increase in slow bands in all subjects during HV, small and nonsignificant in controls and SEEG–, higher and significant in SEEG+, related with flow reduction. Conclusions: Changes in the sympathetic modulation of cerebral vasoconstriction may explain both the pathophysiology of vasovagal syncope and the typical paroxysmal EEG findings.