C. Cossu

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.

25. Low frequency rTMS effect over the right dorsolateral prefrontal cortex in treatment-resistant depression: Effects on affective symptoms, cognitive function and P300 components

Repetitive transcranic magnetic stimulations (rTMS) is an effective tool for treatment-resistant depression (TRD). Only a few studies investigated the response predictors to rTMS and its effects on cognitive functions in depressed patients. Our aims were: (1) confirm the rTMS antidepressant and neurocognitive effects in TRD; (2) evaluate the possible role of the Event-Related Potential P300 as response predictor. Methods: Thirteen patients (aged 41–76) with unipolar or bipolar TDR, received low-frequency rTMS over the right DLPFC in a 3-week trial (15 daily session, 1800 stimuli per session). We assessed rTMS effects on depressive and anxiety symptoms, neurocognitive functions and the P300. Six patients were considered as remitters. The Rey Auditory Verbal Learning Test improved independently from the antidepressant rTMS effect. The latency of P300 was significantly increased both at the baseline and at the end of the rTMS treatment. However considering the acute effect of rTMS, only at the day 15 rTMS determined a significant increase of P300 latency as in healthy subjects. Our data confirm antidepressant effectiveness of rTMS for TDR. Neurocognitive effects were limited to Verbal Learning. P300 seems no to be a response predictor but eventually a Neurophysiological marker of efficacy.

Efficacy of high-frequency (15 Hz) repetitive transcranial magnetic stimulation (rTMS) of the left premotor cortex/dorsolateral prefrontal cortex in decreasing cocaine intake (the MagneTox study): A study protocol for a randomized placebo-controlled pilot trial

BACKGROUND Cocaine use disorder (CUD) is very common and has psychological and physical consequences. Patients with CUD present hypoactivity of the prefrontal cortical area. Thus, excitatory repetitive transcranial magnetic stimulation (rTMS) targeting the premotor cortex/dorsolateral prefrontal cortex (PMC/DLPFC), given its ability to increase prefrontal area excitability and to modulate cortico-limbic activity, could result in a decrease in cocaine intake. METHODS We designed a protocol for a monocentric, randomized, double-blind, placebo-controlled, parallel-group pilot trial, with the principal aim of assessing the efficacy of rTMS on the reduction of cocaine intake. Patients with CUD will be recruited according to inclusion and exclusion criteria, and then randomized to undergo active or sham rTMS. Our rTMS protocol will consist of 15 days of 15Hz rTMS targeting the left PMC/DLPFC. Toxicological and psychiatric assessments, urine drug tests, the Cocaine Craving Questionnaire (CCQ) and the Visual Analogic Scale (VAS) will be used to assess changes from baseline in cocaine intake and craving, mood and quality of life. DISCUSSION Only a few studies have evaluated the efficacy of rTMS for CUD treatment in humans, with limitations concerning small sample size, short treatment duration, different rTMS protocols and the absence of a placebo-controlled group. Our study will attempt to overcome these shortcomings and will provide data that can be used for future larger studies of non-invasive left PMC/DLPFC stimulation as a treatment for CUD.

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.

24. Continuous EEG-SEP monitoring in acute brain injury: Unstable SEP trend preceding neurological deterioration

We describe two patients with acute brain injury who underwent continuous EEG-SEP monitoring: an unusual phase of SEPs amplitude instability preluded to cerebral perfusion alterations in one case and to neurological deterioration up to brain death in the other. Raw and quantitative EEG were continuously recorded. Cortical SEPs after stimulation of median nerves were recorded every hour, with amplitude and latency automatically trended. Patient 1 had a subarachnoid hemorrhage due to a left Middle Cerebral Artery (MCA) aneurysm rupture. Increase of intracranial pressure required left decompressive craniectomy. EEG-SEP monitoring was started on day 7, showing a prolonged instability of left SEP: left MCA vasospasm with temporo-parieto-occipital hypoperfusion was demonstrated. After treatment, hypoperfusion and SEP improved. Patient 2 suffered from a right MCA ischemic stroke, treated with systemic thrombolysis. After four days GCS dropped to 5–6, CT showed a severe hemispheric edema requiring a right decompressive craniectomy. Right SEP was absent but left SEP was normal. On day 6 EEG-SEP monitoring was started, showing left SEP instability and gradual deterioration until day 9, when SEP suddenly and permanently disappeared. On day 10 the brain dead of the patient was declared. In acute brain injury, SEP instability during continuous monitoring is an infrequent pattern, with a high risk of neurological deterioration.

79. Status epileptics and myoclonus in comatose patients after cardiac arrest: To treat or not to treat

Status epilepticus and myoclonus are common in comatose patients after cardiac arrest (Krumholz et al., 1988; Young et al., 1990). There is no consensus on when and for how long to treat this condition. This point became more relevant after introduction of therapeutic hypothermia (TH) because of some patients with MS treated with TH recovered consciousness (Rossetti et al., 2009). We propose a treatment protocol based on clinical-EEG features and somatosensory evoked potentials (SEPs) as prognostic indicator. In patients with absent SEPs we do not treat aggressively with AED considering the poor outcome. In patients with preserved SEPs we treat myoclonus if associated with GPEDs, convulsive status epilepticus and non convulsive status epilepticus (Beniczky et al., 2013). We use a combination of AED (valproate, levetiracetam) with sedation (propofol or midazolam). We present two representative cases in which we describe in more detail our therapeutic approach.

95. Guillain–Barre syndrome: Comparison of neurophysiological standards parameters and validation of criteria for the diagnosis at an early stage

Electrodiagnostic criteria are of support to the diagnosis of GBS. Ho/Hadden (HH) criteria are the ones most commonly used although little specific. Dutch GBS Study Group (DGBSG) criteria seem to be the most sensitive and specific. Both, however, are not sensitive for early diagnosis of GBS. The aim of our study is to determine the more useful criteria in clinical practice and the utility of the proposed criteria for early diagnosis. Prospective study of patients admitted to AOU-Careggi with clinical suspicion of GBS. Clinical evaluation was based on Asbury criteria. Neurophysiological examination included standard nerves conduction, H-reflex, A-wave and distal CMAP duration. We recruited 20 patients, 1/3 met clinical criteria. HH criteria were positive in 4 patients, one of which had a diabetic polyneuropathy. DGBSG criteria were positive only in patients affected by GBS/CIDP. All the proposed criteria for early diagnosis resulted not specific for GBS. The most useful electrodiagnostic criteria are DGBSG. For early diagnosis, however, the standard criteria are not sensitive while the new ones are not specific. Therefore, diagnosis of GBS remains in first instance based on clinical examination. ENG should be performed only in patients meeting clinical criteria to increase level of diagnostic certainty.

P478: Prediction of good and poor outcome in comatose patients after cardiac arrest: the utility of early EEG/SEP recordings during therapeutic hypothermia

go task. In the go/no go task, were presented random visual stimulus (50% green or red). Subjects had to press the mouse button after the green stimuli. Interhemispheric coupling was evaluated by the spectral coherence among all the electrodes covering one hemisphere and matched with those on the other. The task-related results showed that interhemispheric connectivity decreased in delta and increased in alpha band. Furthermore, were observed positive delta and negative alpha correlations with the reaction time. The best performance is anticipated by the better functional coupling of cortical circuits involved during the processing of the sensorimotor information, occurring between the two hemispheres pending cognitive go/ no-go task. The present study provides direct confirmation for a stochastic linking of cortical areas, as revealed by oscillatory synchronization of the two hemispheres in selected EEG rhythms, in determining behaviour performance in a cognitive-motor task.

53. Therapeutic repetitive transcranial magnetic stimulation: neurophysiopathology technician’s role in the therapeutic-rehabilitative use

Repetitive Transcranial magnetic stimulation (rTMS) has proved to modulate cortical excitability according to different stimulation protocols. Recently rTMS has been widely employed in different psychiatric and neurological disorders for therapeutical purposes and, in this context, neurophysiopathology technician’s (NPHT) role is nowadays emerging. The technician takes part in the preliminary interview with the patient in order to get his medical history and informed consent. After that, the technician selects the rTMS proper protocol together with the neurophysiologist. Relationship with a neuropshychiatric patient is crucial since his fragile status and his high expectations about this treatment as rTMS is often seen as the last chance. The technician should make the patient aware of the timing of the potential results to avoid a premature disappointment and a consequent withdrawal. In this therapeutic context, the key role is carried out by the technician who has to manage the balance between prospective results and patient’s expectations. Further considerations have to be made about operator safety since side effects due to prolonged magnetic fields exposure are still not completely understood.