Rhythmical and periodic EEG patterns do not predict short-term outcome in critically ill patients with subarachnoid hemorrhage.

INTRODUCTION: Nonconvulsive seizures and nonconvulsive status epilepticus commonly occur in patients with aneurysmal subarachnoid hemorrhages. When continuous EEG is used in patients in the neuro-intensive care unit, rhythmical and periodic patterns of uncertain significance are frequently encountered. It is unknown how these findings impact patient outcome. METHODS: Patients were enrolled from a single tertiary care center with subarachnoid hemorrhages secondary to ruptured intracranial aneurysm, and either a witnessed seizure or significantly impaired mental status. Prospective clinical, laboratory, imaging, and short-term outcome data were collected. Continuous EEG monitoring was performed and scored according to American Clinical Neurophysiology Society (ACNS) Subcommittee on Research Terminology for Continuous EEG Monitoring. RESULTS: Sixty-eight patients were enrolled. Fifty-four had a poor-grade subarachnoid hemorrhage upon admission. Fifty-one patients had rhythmical or periodic patterns: 33 with periodic discharges and 38 with rhythmic delta activity. Four patients had unequivocal electrographic seizures. Patients did poorly in the short term: 14 died and 42 were severely disabled at discharge. In hospital, mortality was 19.6% in patients with rhythmical or periodic patterns and 23.5% in patients without. Age, female gender, and endovascular treatment had a positive correlation with the occurrence of periodic discharges. However, there was no correlation between rhythmical and periodic patterns and outcome. DISCUSSION: Using the ACNS Research Terminology, it is shown that rhythmical and periodic patterns are very common in critically ill patients with subarachnoid hemorrhage. However, the presence and the abundance of these patterns did not predict short-term outcome in this prospective, single-center observational study. We were unable to show that rhythmical and periodic EEG patterns are an independent predictor for outcome relative to other clinical features. Large multicenter studies will be required to determine if these patterns independently predict outcome and to demonstrate the impact of treatment interventions that are directed at rhythmical and periodic continuous EEG patterns.

Interobserver agreement in the interpretation of EEG patterns in critically ill adults.

The significance of rhythmic and periodic EEG patterns in critically ill patients is unclear. A universal terminology is needed to facilitate study of these patterns, and consistent observer agreement should be demonstrated in its use. The authors evaluated inter- and intraobserver agreement using the standardized terminology (Hirsch et al., J Clin Neurophysiol 2005;22:128-135) recently proposed by the American Clinical Neurophysiology Society. Trained electroencephalographers viewed a series of 10-second EEG samples from critically ill adults (phase I), a set of >/=20-minute EEGs from the same patient cohort (phase II), and then reevaluated the first sample set (phase III). The readers used the proposed terminology to "score" each EEG. For each possible term, interobserver agreement (phases I and II) and intraobserver agreement (phase III) were calculated using pairwise kappa (kappa) values. Moderate agreement beyond chance was seen for the presence/absence of rhythmic or periodic patterns and for localization of these patterns. Agreement for other terms was slight to fair. Inter- and intraobserver agreement were consistently lower for optional terms than mandatory terms. Even when standardized terminology is used, the description of rhythmic and periodic EEG patterns varies significantly. Further refinement of the proposed terminology is required to improve inter- and intraobserver agreement.

Nonconvulsive status epilepticus.

Nonconvulsive status epilepticus (NCSE) is a heterogeneous disorder with multiple subtypes. Although attempts have been made to define and classify this disorder, there is yet no universally accepted definition or classification that encompasses all subtypes or electroclinical scenarios. Developing such a classification scheme is becoming increasingly important, because NCSE is more common than previously thought, with a bimodal peak, in children and the elderly. Recent studies have also shown a high incidence of NCSE in the critically ill. Although strong epidemiological data are lacking, NCSE constitutes about 25-50% of all cases of status epilepticus. For the purposes of this review, we propose an etiological classification for NCSE including NCSE in metabolic disorders, NCSE in coma, NCSE in acute cerebral lesions, and NCSE in those with preexisting epilepsy with or without epileptic encephalopathy. NCSE is still underrecognized, yet potentially fatal if untreated. Diagnosis can be established using an electroencephalogram (EEG) in most cases, sometimes requiring continuous monitoring. However, in comatose patients, diagnosis can be difficult, and the EEG can show a variety of rhythmic or periodic patterns, some of which are of unclear significance. Although some subtypes of NCSE are easily treatable, such as absence status epilepticus, others do not respond well to treatment, and debate exists over how aggressively clinicians should treat NCSE. In particular, the appropriate treatment of NCSE in patients who are critically ill and/or comatose is not well established, and large-scale trials are needed. Overall, further work is needed to better define NCSE, to determine which EEG patterns represent NCSE, and to establish treatment paradigms for different subtypes of NCSE.

Nonaccidental head trauma in infants.

BACKGROUND: Nonaccidental head trauma in infants is the leading cause of infant death from injury. RESULTS AND DISCUSSION: Clinical features that suggest inflicted head trauma include the triad of the so-called shaken baby syndrome, consisting of retinal hemorrhage, subdural, and/or subarachnoid hemorrhage in an infant with little signs of external trauma. Studies have shown that, in general, the average short fall in the home is extremely unlikely to produce either subdural or retinal hemorrhage, although focal injuries such as skull fractures and epidural hemorrhage may be seen. Acceleration/deceleration, especially of the rotational type, is believed to be the most probable mechanism of injury in cases of nonaccidental head trauma. Damage to the cervicomedullary junction and the respiratory centers, with subsequent hypoxia and intracerebral edema, has also been implicated. After the initial trauma and hemorrhage, loss of cerebral autoregulation, breakdown of the blood-brain barrier, and disruption of ionic homeostasis occur, leading to brain edema and cytotoxicity. Cellular damage can involve large volumes of tissue, without respecting vascular territories. CONCLUSION: Overall, a satisfactory biomechanical model is lacking, and the criminal nature of abusive injury makes it difficult to perform systematic, controlled studies. Unfortunately, outcomes are poor, and the rate of repeated abusive episodes is high. Future research should focus on the development of a satisfactory research model and on prevention strategies.

Ictal eye closure is a reliable indicator for psychogenic nonepileptic seizures.

Using data from video-EEG monitoring, the authors studied whether ictal eye closure was a reliable indicator of psychogenic nonepileptic seizures (PNES). Among the 52 patients with PNES, 50 consistently closed their eyes, while 152 of the 156 patients with epileptic seizures (ES) opened their eyes during seizures. These findings suggest that ictal eye closure is a highly reliable indicator for PNES, while ictal eye opening is an indicator of ES.

Evaluation of clinical diagnostic criteria for psychogenic movement disorders.

Previous studies showed that there are certain features suggestive of a psychogenic disorder, and Fahn and Williams proposed criteria for psychogenic movement disorders. Data on the sensitivity and specificity of these criteria are lacking. We expanded on the Fahn and Williams criteria to create a new set of diagnostic criteria. We retrospectively reviewed 79 patients in a movement disorders specialty clinic. We applied the proposed diagnostic criteria to both cases and controls and analyzed sensitivity and specificity. The diagnostic criteria correctly identified "clinically probable" (or better) psychogenic movement disorders with a sensitivity of 83% and specificity of 100%. For "clinically possible" or greater, sensitivity was 97% and specificity was 96%. In addition, a significantly higher proportion of patients with psychogenic disease were female and reported either a family history of neurological disease or other exposure to neurological disease (P = 0.001 and 0.01, respectively). The diagnostic criteria are simple to apply and have high sensitivity and specificity for psychogenic movement disorders. Also, we report a correlation between previous exposure to a disease model and psychogenic disease.