Riccardo Carrai

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

OBJECTIVEnTo 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.nnnDESIGNnA prospective study.nnnSUBJECTSnFifty-two patients with hemiparesis were enrolled one month post-stroke; 38 patients concluded the study at 12 months.nnnMETHODSnMotor 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.nnnRESULTSnAt 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.nnnCONCLUSIONnMotor 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.

The organisation of spinal projecting brainstem neurons in an animal model of muscular dystrophy: A retrograde tracing study on mdx mutant mice

Previous studies we performed on the mdx mouse demonstrated marked central nervous system alterations in this model of human Duchenne muscular dystrophy, such as reduction in number and pathological changes of cortico-spinal neurons. Prompted by these findings we extended the survey of the mdx brain to the major brainstem-descending pathways: the rubro-, vestibulo-, reticulo-, and raphe-spinal projections. Horseradish peroxidase microinjections were performed in the cervical spinal cord of mdx and control mice. The rubro-spinal neurons were found to be significantly reduced in mutants compared to controls. The vestibulo-spinal, reticulo-spinal, and raphe-spinal cell populations, though less numerous in mdx than in control mice, were instead substantially spared. Our data further unveil the selective nature of mdx brain damage indicating a marked and selective involvement of the highest centers for motor control.

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

OBJECTIVEnSeveral 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.nnnMETHODSnRREP 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.nnnRESULTSnRREP 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.nnnCONCLUSIONSnThe 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.

Blunted respiratory-related evoked potential in awake obstructive sleep apnoea subjects: A NEP technique study

OBJECTIVEnRespiratory-related evoked potentials (RREP) elicited by transmural pressure in obstructive sleep apnoea (OSA) subjects have reported conflicting data. Different features of pressure stimuli and/or in the timing of stimuli application seem to account for these contradictory results. The negative expiratory pressure (NEP) technique, highly reproducible in terms of rise time and pressure values, allows to minimize the methodological confounding factors. We determined whether the afferent activity from the upper airway (UA) is altered in OSA subjects.nnnMETHODSnRREP potentials were examined in 10 OSA and in 12 non-apnoeic awake subjects by means of the NEP technique.nnnRESULTSnAll controls showed a cortical response to all pressure stimuli. All OSA subjects showed responses to -5 and -10 cmH(2)O whereas six of them showed no responses to -1 cmH(2)O. The amplitude of the P22, N45 and P85 components of the RREP was significantly reduced in OSA with respect to the controls in response to both the -5 and -10 cmH(2)O stimuli. We found no significant differences in latencies.nnnCONCLUSIONSnAwake OSA subjects had a raised threshold to pressure stimuli and blunted respiratory-related evoked potentials.nnnSIGNIFICANCEnThese data indicate a deficit in afferent activity in the UA.

Prevalence of limb muscle dysfunction in patients with chronic obstructive pulmonary disease admitted to a pulmonary rehabilitation centre

OBJECTIVEnAssessment of needle electromyography (nEMG) may complement previous data on limb muscle dysfunction (LMD) in patients with chronic obstructive pulmonary disease (COPD). We attempted to quantify the prevalence of LMD and assess its impact on clinical outcomes in patients admitted to a rehabilitation programme.nnnMETHODSnOne hundred and thirty-two clinically stable patients were consecutively enrolled. They underwent spirometry and the following primary outcomes were evaluated: St. George respiratory questionnaire (SGRQ), functional independence measure (FIM) questionnaire and a 6-min walking test (6MWT). One hundred and fourteen patients underwent nEMG. The frequency of LMD was related to COPD stage and chronic dyspnoea.nnnRESULTSnnEMG detected myopathic signs in 36.8% of the patients. LMD was found even in early stages of COPD. FIM and 6MWT were significantly lower, and SGRQ tended to be higher at each COPD stage in patients with LMD. However, the 6MWT rate of decay across the COPD stages was similar in patients with and without LMD.nnnCONCLUSIONSnLMD might not be restricted to patients with severe airway obstruction and regardless of COPD stage, contributes to functional limitation of these patients.nnnSIGNIFICANCEnThe putative role of LMD in motor limitations indicates the need to assess it early onto better organise a specific training programme as part of general pulmonary rehabilitation in COPD patients.

Amplitude Instability of Somatosensory Evoked Potentials as an Indicator of Delayed Cerebral Ischemia in a Case of Subarachnoid Hemorrhage

We describe a 55-year-old male patient with a subarachnoid hemorrhage (SAH) as a result of left middle cerebral artery (MCA) aneurysm rupture, who underwent continuous electroencephalogram (EEG) and somatosensory evoked potential (cEEG-SEP) monitoring that showed an unusual SEP trend pattern. EEG was continuously recorded, and SEPs following stimulation of median nerves were recorded every 50 minutes, with the amplitude and latency of the cortical components automatically trended. An increase in intracranial pressure required a left decompressive craniectomy. cEEG-SEP monitoring was started on day 7, which showed a prolonged (24 hours) instability of SEPs in the left hemisphere. During this phase, left MCA vasospasm was demonstrated by transcranial Doppler (TCD), and computed tomography perfusion (CTP) showed a temporo-parieto-occipital ischemic penumbra. Following intravascular treatment, hypoperfusion and the amplitude of cortical SEPs improved. In our case, a prolonged phase of SEP amplitude instability during vasospasm in SAH correlated with a phase of ischemic penumbra, as demonstrated by CTP. In SAH, SEP instability during continuous monitoring is a pattern of alert that can allow treatments capable of avoiding irreversible neurological deterioration.

Improvement on the Coma Recovery Scale–Revised During the First Four Weeks of Hospital Stay Predicts Outcome at Discharge in Intensive Rehabilitation After Severe Brain Injury

OBJECTIVESnTo evaluate the prognostic utility of serial assessment on the Coma Recovery Scale-Revised (CRS-R) during the first 4 weeks of intensive rehabilitation in patients surviving a severe brain injury.nnnDESIGNnProspective cohort study.nnnSETTINGnAn intensive rehabilitation unit.nnnPARTICIPANTSnPatients (N=110) consecutively admitted to the intensive rehabilitation unit. Inclusion criteria were (1) a diagnosis of unresponsive wakefulness syndrome (UWS) or minimally conscious state (MCS) caused by an acquired brain injury, and (2) aged >18 years.nnnINTERVENTIONSnAll patients underwent clinical evaluations using the Italian version of the CRS-R during the first month of hospital stay.nnnMAIN OUTCOME MEASURESnBehavioral classification on the CRS-R and the score on the Glasgow Outcome Scale (GOS) at final discharge. Patients transitioning from UWS to MCS or emergence from MCS (E-MCS), and from MCS to E-MCS were classified as patients with improved responsivenessxa0(IR).nnnRESULTSnAfter a mean ± SD hospital stay of 5.3±2.7 months, 59 of 110 patients (53.6%) achieved IR. In the multivariable analysis, a higher CRS-R score change at week 4 (odds ratio =1.99; 95% confidence interval [CI], 1.49-2.66; P<.001) was the only significant predictor of IR at discharge. Fifty-three patients (48.2%) were classified as severely impaired at discharge (GOS=3). In the multivariable analysis, higher GOS scores were related to a higher CRS-R score at admission (B=.051; 95% CI, .027-.074; P<.001), a higher CRS-R score change at week 4 (B=.087; 95% CI, .064-.110; P<.001), and an absence of severe infections (B=-.477; 95% CI, -.778 to -.176; P=.002).nnnCONCLUSIONSnAn improvement on the total CRS-R score and on different subscales across the first 4 weeks of inpatient rehabilitation discriminates patients who will have a better outcome at discharge, providing information for rehabilitation planning and for communication with patients and their caregivers.

10. Neurophysiological prognosis in comatose patients after cardiac arrest: The Italian Multicentric Study (ProNeCA)

SEPs are reliable predictor of poor outcome in comatose patients after cardiac arrest (CA). Recently also the role of EEG has been reassessed. To evaluate the prognostic value of EEG and SEPs association in post-anoxic coma at different recording time. We included comatose patients after CA. EEG and SEPs were recorded within 12u202fhs and at 72u202fhs after CA. EEG was classified into grade 1(“continuous”/“nearly-continuous”) and grade 2(discontinuous/burst-suppression/suppression/isoelectric). SEPs were dichotomized into “bilaterally absent” (BA) and “present”. Outcome was evaluated at 6u202fmonths by GOS. “Recovery of consciousness” was considered good outcome. Ten centers took part to the study and 282 patients were included. EEG and SEPs were recorded in 141 within 12u202fhs in 162 at 72u202fhs. Grade 1 EEG at 12u202fhs always predicted good outcome, grade 2 pattern at 72u202fhs predicted poor outcome with higher predictive power. BA SEPs always predicted poor outcome. Grade 1 EEG was always associated with present SEPs. EEG is a reliable time-dependent predictor of good outcome (within 12u202fh) and poor outcome (after 72u202fh). SEP is time-independent predictor of poor outcome. Early grade 1 EEG is never associated with BA SEP. Early association recordings of EEG and SEPs increase of the reliability of prognosis prediction in post-anoxic coma.

O80 Neurophysiological prognosis in comatose patients after cardiac arrest: The italian multicentric study (PRONECA) – preliminary data-

Objective To evaluate the prognostic value of EEG and SEPs association in post-anoxic comatose patients at different recording time from cardiac arrest (CA) a italian multicentric study. Methods Comatose patients after CA were included.EEG and SEPs were recorded within 12xa0h and at 72xa0h after CA. EEG was classified into “non-continuous” (low voltage, isoelectric, burst-suppression) and “continuous” (other patterns except epileptiform). SEPs were dichotomized into “bilaterally absent” (BA) and “present”. Outcome was evaluated at 6xa0months by GOS. “Recovery of consciousness” was considered good outcome. Results At the moment four center took part to the study and 230 patients were included. EEG and SEPs were recorded in 92 within 12xa0h in 102 at 72xa0h. “Continuous” EEG pattern at 12xa0h always predicted good outcome, “non-continuous” pattern at 72xa0h always predicted poor outcome. BA SEPs always predicted poor outcome. Early “continuous” EEG pattern was always associated with present SEPs. Conclusion EEG is a reliable time-dependent predictor of good outcome (within 12xa0h) and poor outcome (after 72xa0h). SEP is time-independent predictor of poor outcome. Early “continuous” EEG and BA SEPs are never associated together. Significance The combination of EEG/SEP findings allows prediction of good and poor outcome (within 12xa0h after CA) and of poor outcome (after 48–72xa0h). Recording of EEG and SEPs in the same patients allows always an increase in the number of cases correctly classified and an increase of the reliability of prognostication in a single patient due to concordance of patterns.