A. Grippo

Continuous EEG-SEP monitoring of severely brain injured patients in NICU: methods and feasibility.

AIMS To evaluate the feasibility of a continuous neurophysiologic monitoring (electroencephalography (EEG)-somatosensory evoked potentials (SEPs)) in the neuro-intensive care unit (NICU), taking into account both the technical and medical aspects that are specific of this environment. METHODS We used an extension of the recording software that is routinely used in our unit of clinical neurophysiology. It performs cycles of alternate EEG and SEP recordings. Raw traces and trends are simultaneously displayed. Patient head and stimulator box are placed behind the bed and linked to the ICU monitoring terminal through optic fibers. The NICU staff has been trained to note directly clinical events, main artefacts and therapeutic changes. The hospital local area network (LAN) enables remote monitoring survey. RESULTS Continuous EEG (CEEG)-SEP monitoring was performed in 44 patients. Problems of needle detachment were seldomly encountered, thanks to the use of a sterile plastic dressing, which covers needles. We never had infection or skin lesions due to needles or the electrical stimulator. The frequent administration of sedative at high doses prevented us from having a clinically valuable EEG in several cases but SEPs were always monitorable, independently of the level of EEG suppression. The diagnosis of seizures and non-epileptic status was based on raw EEG, while quantitative EEG (QEEG) was used to quantify ictal activity as a guide to treatment. CONCLUSIONS EEG and EP waveforms collected in NICU were of comparable quality to routine clinical measurements and contained the same clinical information. A continuous SEP monitoring in a comatose and sedated patient in NICU is not technically more difficult and potentially less useful than in operating room. This monitoring appears to be feasible provided the observance of some requirement regarding setting, electrodes, montages, personnel integration, consulting and software.

Prognostic value of somatosensory evoked potentials in comatose children: a systematic literature review

PurposeTo review the predictive powers of SEPs in comatose children after acute brain injury.MethodsMEDLINE, EMBASE, OVID, ISI Web of Knowledge, BIOMED Central and the Cochrane Library (1981–2007) were searched. First, predictive values were calculated for each primary study. Second, we analysed effects of different factors on the SEP diagnostic odds ratio by meta-regression. Third, we compared SEP predictive values in children and in adults.ResultsWe selected 14 studies covering 732 patients; analysis was conducted in 11, while the other 3 were used for simple qualitative examination. In individual papers, the presence of SEP predicted favourable outcomes as shown by the area under both sROC curves being 0.958. The same value was shown by SEP absence for predicting unfavourable outcomes. All covariates showed no significant effects on diagnostic accuracy, but only a slight non-significant trend. For SEP grading, a simple sub-group analysis showed a high predictive value for non-awakening for absence of SEPs (PPV 97.0%) and a high prognostic power to predict awakening for normal SEPs (PPV 92.2%). Pathological SEPs did not show reliable predictivity. In children, the presence of SEPs showed a high prognostic power similar to that in adults.ConclusionThis study supports the use of SEPs in the integrated process of outcome prediction after acute brain injury in children. Caution is recommended in predicting unfavourable outcomes in patients with an absence of SEPs in both TBI and HIE comas. Future studies are needed to resolve the issue of the effect of aetiology and age on SEPs predictive power.

PROGNOSTIC VALUE OF MOTOR EVOKED POTENTIALS IN MOTOR FUNCTION RECOVERY OF UPPER LIMB AFTER STROKE

OBJECTIVE To determine the prognostic value of clinical assessment and motor evoked potentials for upper limb strength and functional recovery after acute stroke, and to establish the possible use of motor evoked potentials in rehabilitation. DESIGN A prospective study. SUBJECTS Fifty-two patients with hemiparesis were enrolled one month post-stroke; 38 patients concluded the study at 12 months. METHODS Motor evoked potentials were recorded at baseline and after one month. Upper limb muscular strength (Medical Research Council Scale, MRC) and functional tests (Frenchay Arm Test, Barthel Index) were used as dependent outcome variables 12 months later. Motor evoked potentials were classified as present or absent. Predictive values of motor evoked potentials and MRC were evaluated. RESULTS At 12 months, patients with baseline recordable motor evoked potentials showed a good functional recovery (positive predictive value 94%). The absence of motor evoked potentials did not exclude muscular strength recovery (negative predictive value 95%). Motor evoked potentials had a higher positive predictive value than MRC only in patients with MRC < 2. CONCLUSION Motor evoked potentials could be a supportive tool to increase the prognostic accuracy of upper limb motor and functional outcome in hemiparetic patients, especially those with severe initial paresis (MRC < 2) and/or with motor evoked potentials absent in the post-stroke acute phase.

Respiratory-related evoked potential and upper airway transmural pressure change by using the negative expiratory pressure (NEP) device

OBJECTIVE Several studies have previously shown respiratory related evoked potentials (RREP) in humans elicited by mechanical stimuli applied on upper airways (UA). According to us, heterogeneous findings, concerning latencies and amplitudes, have been reported because of the different timing of stimuli application during the respiratory cycle and/or features of pressure stimuli. Therefore we evaluated the cortical response evoked by transmural pressure changes at the mouth induced by a negative expiratory pressure (NEP) device. METHODS RREP were recorded in 22 healthy non-obese, non-snoring volunteers. The subjects were studied awake in seated position during quiet breathing. Three different pressure levels were applied, in a random order, 200 ms after the beginning of expiration. Cortical electrical responses were recorded from scalp electrodes at Fz, Cz, and Pz scalp location (international 10-20 system) referenced to the linked earlobes. RESULTS RREP responses consisted of two negative (N45, N120) and two positive (P22, P85) waves. There was no significant effect of pressure or electrode on component latencies. The P22 wave (PRESSURE: F(df 2,42)=6.66, P<0.01), the N45 wave (PRESSURE: F(df 2,42)=16.51, P<0.001), and the P85 wave (PRESSURE: F(df2,42)=15.15, P<0.001) increased significantly theyr amplitude with increasing from pressure stimuli 1 to 10 cmH2O. CONCLUSIONS The present results suggest that the UA NEP application in humans is a reliable way of evoking cortical responses. The experimental features that we described allow us to minimize the confounding factors in evaluating RREPs. The NEP device appears to be a useful tool for investigation of the neurobiology of UA sensation in humans.

Effect of limb muscle fatigue on perception of respiratory effort in healthy subjects.

The role of nonrespiratory peripheral afferents in dyspnea perception has not been fully elucidated yet. Our hypothesis is that fatigue-induced activation of limb muscle metaboreceptors served by group IV fine afferent fibers may impact on respiratory effort perception. We studied 12 healthy subjects breathing against progressive inspiratory resistive loads (10, 18, 30, 40, and 90 cmH(2)O x l(-1) x s) before and after inducing low-frequency fatigue of quadriceps muscle by repeating sustained contractions at > or = 80% of maximal voluntary contraction. Subjects also underwent a sham protocol while performing two loaded breathing runs without muscle fatigue in between. During the loaded breathing, while subjects mimicked the quiet breathing pattern using a visual feedback, ventilation, tidal volume, respiratory frequency, pleural pressure swings, arterial oxygen saturation, end-tidal partial pressure of CO(2), and dyspnea by a Borg scale were recorded. Compared with prefatigue, limb muscle fatigue resulted in a higher increase in respiratory effort perception for any given ventilation, tidal volume, respiratory frequency, pleural pressure swings, end-tidal partial pressure of CO(2), and arterial oxygen saturation. No difference between the two runs was observed with the sham protocol. The present data support the hypothesis that fatigue of limb muscles increases respiratory effort perception associated with loaded breathing, likely by the activation of limb muscle metaboreceptors.

Single electroencephalographic patterns as specific and time-dependent indicators of good and poor outcome after cardiac arrest

OBJECTIVE To evaluate the prognostic value of single EEG patterns recorded at various time-frames in postanoxic comatose patients. METHODS This retrospective study included 30-min EEGs, classified according to the definitions of continuity of background activity given by the American Clinical Neurophysiology Society. Isoelectric pattern was distinguished from other suppressed activities. Epileptiform patterns were considered separately. Outcome was dichotomised based on recovery of consciousness as good (Glasgow Outcome Scale [GOS] 3-5) or poor (GOS 1-2). RESULTS We analysed 211 EEGs, categorised according to time since cardiac arrest (within 12h and around 24, 48 and 72h). In each time-frame we observed at least one EEG pattern which was 100% specific to poor or good outcome: at 12h continuous and nearly continuous patterns predicted good outcome and isoelectric pattern poor outcome; at 24h isoelectric and burst-suppression predicted poor outcome; at 48 and 72h isoelectric, burst-suppression and suppression (2-10μV) patterns predicted poor outcome. CONCLUSIONS The prognostic value of single EEG patterns, defined according to continuity and voltage of background activity, changes until 48-72h after cardiac arrest and in each time-frame there is at least one pattern which accurately predicts good or poor outcome. SIGNIFICANCE Standard EEG can provide time-dependent reliable indicators of good and poor outcome throughout the first 48-72h after cardiac arrest.

Neurophysiological prediction of neurological good and poor outcome in post‐anoxic coma

Investigation of the utility of association between electroencephalogram (EEG) and somatosensory‐evoked potentials (SEPs) for the prediction of neurological outcome in comatose patients resuscitated after cardiac arrest (CA) treated with therapeutic hypothermia, according to different recording times after CA.

Fatigue in primary biliary cirrhosis: a possible role of comorbidities.

Background and aims Fatigue is considered to be a specific manifestation of primary biliary cirrhosis (PBC). Recent reports have, however, questioned these findings. Considering the high rate of comorbidities in PBC patients and the fact that fatigue is a multifactorial symptom, we hypothesized that it might also be due to nonhepatic causes. Our aim was to evaluate fatigue in PBC patients and its relationship with comorbidities and depression. Methods We enroled 49 Italian PBC patients (44 women; mean age: 58.9 years, range: 21–73 years) and 30 matched healthy controls, who completed the Fatigue Impact Scale (FIS), Modified FIS (MFIS), Fatigue Severity Score (FSS) and Rand Medical Outcomes Study Depression Screener. Comorbidities and several clinical and biochemical data were investigated. Linear regression, analysis of variance and post-hoc analysis were applied. Results Fatigue was higher in patients than in controls (FIS: 33 vs. 24; MFIS: 24 vs. 14; FSS: 3.3 vs. 1.9). Physical domain was significantly different in all the three questionnaires (FIS: P=0.05; MFIS: P=0.002; FSS: P=0.0002). Comorbidities (38% of patients) were independently associated with higher fatigue scores (FIS: 45; MFIS: 32; FSS: 3.3). Depressed patients (30%) were more fatigued, even if not always significantly (FIS: 43; MFIS: 29; FSS: 3.5), than controls and patients with no depression. Patients without comorbidities or depression (51%) did not have higher fatigue than controls (FIS: 20; MFIS: 17; FSS: 2.4). Conclusions Fatigue in patients with PBC was higher, but not always significantly, than in healthy controls. Comorbidities and depression might have played a role in its pathogenesis. Our data arouse doubts about the specificity of fatigue in PBC and the pathogenetic role of liver impairment.

Intrathecal synthesis of anti-HIV antibodies in AIDS patients

We studied the production within the CNS of anti-HIV antibodies, of non-specific IgG, and the presence of HIV antigens in the serum and CSF of 28 HIV infected patients belonging to group IV in the Center for Disease Control classification. CSF and serum were diluted under optimal conditions to equalize their IgG content, to enable us to better interpret serum and CSF reactivity by means of Western blot and ELISA. Under these conditions, no patient displayed a limited immunological response profile in CSF as compared to serum. On the contrary, there was intrathecal synthesis (ITS) of anti HIV-antibodies in Western blot test in 21 patients for gp160 and ITS was demonstrable for env, gag, and pol products. ITS of anti-HIV antibodies occurred in 17 patients when measured by ELISA. ITS of non specific IgG and HIV-antigens in CSF were less frequent. A marked anti-HIV response is evident in the CSF-CNS compartment in the later phases of the HIV infection.

Electrophysiological study of neurologically asymptomatic HIV1 seropositive patients

EEGs, brainstem auditory evoked potentials (BAEPs) and auditory event‐related potentials (ERPs) were recorded from 33 individuals infected with the human immunodeficiency virus, type 1 (HIV1 + patients: 13 CDC Class II or III; 20 Class IV). All were neurologically asymptomatic, non‐demented, and had a past history of intravenous drug abuse. Sixteen age‐ and sex‐matched normals and 10 HIV1 ‐ former drug addicts served as controls. Half of the HIV1 + and HIV1 ‐ subjects displayed mild EEG anomalies and, except for one HIV1 + patient, BAEPs were normal in both groups. ERPs were normal in all HIV1 ‐ subjects but anomalous (longer latencies of components P2, N2, P3; reduced amplitude of P3) in 9 HIV1 + patients (27%), the incidence of such anomalies being higher for Class IV than Class II/III patients. Auditory ERPs proved the most sensitive and specific of these electrophysiological procedures in detecting subclinical central nervous system involvement in HIV1 infection.