The two survival cases of alpha-pattern coma caused by large amounts of hypnotica and neuroleptica

The EEGs of two men (42 and 63 years old) in coma who took large amounts of hypnotica and neuroleptica for intended suicides were occupied by an alpha pattern, and the patients were diagnosed as alpha-pattern coma. The prominent pattern in their EEGs changed from an alpha pattern to a theta pattern, and subsequently into an alpha pattern of low amplitude. The patients recovered without any residual neurological symptoms. It has been confirmed by our two cases, as well as by other reported cases, that the outcome of the alpha-pattern coma caused by drug poisoning is favorable. It is concluded that a longitudinal EEG recording should be performed as early as possible when the patient is in a comatose state.     

Physiologic and prognostic significance of "alpha coma".

A patient with posthypoxic "alpha coma" is described whose EEGs were recorded before coma, within two hours following the onset of coma and after recovery. The differences observed between the alpha activity during coma and that seen before and after suggest that the alpha activity during coma and the physiologic alpha rhythm are different phenomena. This case, as well as others reported, also suggests that "alpha coma" resolving in the first 24 hours following hypoxia may have a better prognosis than "alpha coma" detected after the first day, and stresses the need for EEG monitoring begun in the immediate period following hypoxia in order to assess accurately the prognostic significance of this EEG pattern in the early stages of postanoxic encephalopathy. The aetiology of "alpha coma" also affects outcome. The survival rate appears higher in patients with respiratory arrest than in those with combined cardiopulmonary arrest.     

"Alpha-pattern coma" in high voltage electrical injury.

Two cases are reported in which reversible deep coma subsequent to high voltage electrical injury occurred in association with alpha frequencies in the EEG. The EEG pattern differs from the alpha rhythm of the normal awake patient by its diffuse distribution and unresponsiveness to a variety of stimulation. The term "alpha-pattern coma" is introduced to designate the occurrence of this pattern in comatose patients. The EEG in the cases described initially demonstrated activity in the alpha frequency which occurred in a generalized distribution and was unresponsive to stimulation. During the early stages of recovery an increased incidence of theta and delta activity was observed. The recovery records contained a low voltage alpha rhythm and responded to photic stimulation. The literature on this subject is reviewed and the possible modes of pathogenesis are discussed. The authors conclude that such examples of alpha-pattern coma are the result of diffuse cerebral damage and might be detected more frequently in comatose patients who survive if these patients are studied earlier in their clinical course with EEGs.     

Alpha-coma. Electroencephalographic, clinical, pathologic, and etiologic correlations.

"Alpha-coma" denotes the conjunction of clinical coma with an electroencephalographic pattern resembling that of normal wakefulness and predominantly consisting of alpha activity. Clinical, EEG, and pathologic data from 13 patients with this syndrome were reviewed. The patients were divided into two groups, based on the pathogenesis of their conditions. The first group consisted of eight patients with brain stem strokes, and the second group consisted of five patients with diffuse hypoxic encephalopathy resulting from cardiac or pulmonary arrest. There were some differences between the EEGs of the two groups. In the first group, the alpha pattern was located more posteriorly, showed more variability and reactivity, and was more persistent in sequential recordings. In the second group, the alpha activity was transient and showed little reactivity. In both groups, this pattern indicated a poor prognosis for survival.     

Differentiation of alpha coma from awake alpha by nonlinear dynamics of electroencephalography

The electroencephalogram, as a probe of scalp-recorded electrical activity arising from the human cortex, provides useful information because of its temporal and spatial organization. Recent developments in nonlinear dynamics suggest that an object can be constructed in an n-dimensional space out of a temporal sequence of data such as an EEG signal and that its organization is characterized by the dimensionality of the object (in this case, human brain activity). We have carried out an analysis of a set of alpha coma EEG patterns in comparison to the awake alpha EEG patterns of normal volunteers and patients. Alpha coma recorded from a single channel is visually indistinguishable from normal resting alpha due to its similar frequency spectrum (a broad-band spectrum with 1/f characteristics). Our results show that alpha coma dimensionality, however, differs from that of normal alpha in that it has a greater variability over different temporal segments of EEG. Single channel recordings in 7 patients with alpha coma were differentiable from those of 10 subjects with “normal” EEGs. Through dynamic analysis of the EEG, novel methods of signal extraction from EEG may become evident and applicable to clinical practice.     

Alternative cerebral generators and circuitry pathways in alpha coma revealed by independent component analysis

ObjectiveThis study investigates the generators of alpha coma activity and the probable cerebral pathways involved in alpha coma patients.MethodsThis study uses independent component analysis (ICA) and dipole fitting algorithm to locate the cerebral generators in alpha coma and normal alpha rhythms.ResultsDistinct distributions of the source generators for alpha activity were noted in alpha coma. They were localized to the anterior neocortical and subcortical regions, which includes caudate nucleus, midbrain and hypothalamus. In addition, the two patients who survive long term have five independent components identified vs. the other five patients who demised only had one or two independent components.ConclusionsThe findings showed that alpha activity could be generated using alternative generators and pathways. This is probably due to the disinhibition of the normally inhibited pathways in coma. The presence of less independent components is probably a marker of less preserved brain tissue and predicts worse outcome.SignificanceThis is the first known human study using the ICA method to localize the cerebral generators in alpha coma. It might provide a new dimension of interpreting clinical EEGs in patients with alpha coma. It also might have significant application in predicting the clinical outcomes.     

Neurophysiological assessment of alpha pattern coma.

Somatosensory evoked potentials, blink reflexes, and H wave reflexes, were recorded on several days from three patients with alpha pattern coma. Coma was secondary to cardiac arrest in two cases and to brainstem infarction in one. Results are compatible with damage to the brainstem reticular formation with sparing of thalamo-cortical circuits as the main physiopathological characteristic of alpha pattern coma. This condition should not be regarded as a discrete entity when establishing the prognosis of patients in coma, since they only differ from other patients in coma from the point view of the EEG record.     

Prognostic significance of alpha frequency EEG rhythm in coma after cardiac arrest.

Sixty-five patients who remained in coma for more than 24 hours after resuscitation from cardiac arrest were divided into two groups according to their EEGs. Thirteen patients were found to have rhythm of alpha frequency while 52 had the usual EEG findings after cerebral anoxia. Three patients from the group with alpha frequency EEG rhythms regained full consciousness but showed severe sequelae. Our results suggest that the prognosis of comatose patients with EEG rhythm of alpha frequency is no poorer than that of other individuals who are comatose after cardiac arrest.     

A reappraisal of rhythmic coma patterns in children

OBJECTIVE: This study was designed to determine the prevalence of rhythmic coma patterns in comatose children and to ascertain the prognostic significance of reactive rhythmic coma patterns. METHODS: We retrospectively analyzed and classified electroencephalogram (EEGs) in comatose children between two months and 18 years of age during the period 1996 - 2003 according to modified Young's classification. Outcome at one-year was scored according to the Paediatric Cerebral and Overall Performance Category Scale. Outcomes were compared using Fisher's exact test and Mann-Whitney test. RESULTS: Analysis of 63 electroencephalogram (EEG) records in 38 patients showed rhythmic patterns in 19 records (30.2%; 9 alpha, 4 spindle, 4 theta and 2 beta coma patterns, total number of children = 14). Aetiology and outcome of alpha coma patterns and other rhythmic coma patterns were similar. In five children, one type of rhythmic pattern changed to another. Records with reactive rhythmic coma 66.7% (6/9), were associated with favourable outcome. Sixty percent of the records (6/10 records in seven children) with non-reactive pattern were associated with unfavourable outcome. This clinically significant difference did not reach statistical significance (lower Paediatric Cerebral and Overall Performance Category Scale score p= 0.14; favourable outcome p=0. 19). CONCLUSION: Rhythmic coma patterns in comatose children are not uncommon. Aetiology, reactivity and outcome of individual patterns are similar and thus make the rhythmic coma patterns distinct EEG signatures in comatose children. There was a clinically significant better outcome with reactive rhythmic coma patterns.     

Alpha rhythm and alpha-like activity in coma

A normal waking EEG was obtained on a 22 year old man four days prior to cardiopulmonary arrest. Three days after resuscitation the EEG showed the pattern of alpha-like activity while the patient remained in deep coma. Since the EEGs were recorded by the same technician using the same 16 channel electroencephalograph and montages, it is possible to compare in the same individual these alpha-frequency activities before and after arrest. The alpha-like activity of coma does not resemble the waking alpha rhythm in amplitude, frequency, spatial distribution, variability and reactivity.     

Etiology, neurologic correlations, and prognosis in alpha coma.

OBJECTIVE: To determine the factors affecting prognosis in alpha coma (AC). METHODS: Retrospective review of 36 study patients, 36 control coma patients matched for age and etiology, and meta-analysis of 335 cases in the world literature. RESULTS: Principal causes were cardiorespiratory arrest (CRA) (21 patients); infection, metabolic dysfunction, head trauma (3 each); and drugs, stroke and hypoxia (2 each). Outcome was predicated by EEG reactivity to noxious stimuli. Fourteen of the 15 patients with reactive EEGs, had measurable outcome, 8 awoke - all but two had etiologies other than CRA. Fourteen of 19 patients without EEG reactivity died; two had support discontinued and 3 awoke. Following CRA, 16/21 patients died and 3 had support discontinued. Only 3 patients made a good recovery - all with toxic or metabolic etiologies. Literature meta-analysis of 335 cases showed that overall, AC carried a poor prognosis (76% died). CRA (226 cases) had an 88% mortality; strokes (29 cases), a 90% mortality; hypoxia without cardiac arrest (28 cases), a 61% mortality; drug-induced AC (25 cases), an 8% mortality. CONCLUSIONS: Although the cause of AC largely predicts outcome, EEG reactivity in AC predicted survival: most patients with reactivity awoke; most of those without, died. Few survivors had meaningful recovery.     

Fourteen and six c/sec positive bursts in comatose patients.

Of ten patients with Reye's syndrome, there were five with stage II or III coma where EEGs revealed 14 c/sec positive bursts in a background of diffuse delta waves. Positive bursts disappeared upon EEG improvement in two survivors and when the EEG became nearly isoelectric in two other patients. Although 14 and 6 c/sec positive bursts are seen commonly during sleep in normal young persons, their occurence in association with diffuse delta waves in acutely ill, comatose patients has been rarely reported. It is not certain whether the present findings should be regarded as selective preservation of a type of sleep pattern or whether there are special factors that enhance positive bursts in stage II or III coma of Reye's syndrome.     

Incidence and prognostic value of spindles in post-traumatic coma

One hundred and thirty-three EEGs were analysed from 80 comatose patients with signs of brain stem impairment due to head/brain injury. Seventy EEGs were taken in acute coma on day 1 or 2 after brain injury. Sixty-three EEGs were recorded in prolonged coma 3-12 days after brain injury. Brain stem involvement was divided by neurological signs and by CT scan into secondary lesions due to supratentorial mass displacement and primary lesions due do direct violence to the brain stem. Different EEG patterns were observed, but spindle activity was of special interest. Spindles were classified as typical (easily recognizable, well organized, 12-14 c/sec activity) or atypical (hardly recognizable, distorted form, 6-11 c/sec activity). Furthermore, asymmetries of spindles were noted. The spindles and their alterations were related to different stages of outcome. Spindles were seen in 91% of the EEGs in acute coma and in 30% in prolonged coma. In acute coma due to secondary brain stem involvement a good outcome was heralded by the occurrence of typical symmetrical spindles combined with early stages of secondary brain stem impairment at neurological examination. In cases of primary brain stem involvement typical spindles also suggested a good prognosis despite the observation of serious clinical signs (decerebrate posturing). The percentage of spindle activity decreased, and distortion and asymmetry of spindles increased with the worsening of outcome. Severe intracerebral lesions (confirmed by clinical and CT scan examinations) led to distortion, asymmetry and finally disappearance of spindles. In prolonged coma spindle activity was markedly reduced regardless of the final outcome. When spindles were present atypical and asymmetric forms significantly increased in patients with bad outcome. There were no significant differences in spindle activity in the different outcome categories, if primary and secondary brain stem lesions were compared.     

Electro-neurological correlations of the early stages of acute traumatic secondary midbrain and bulbar brain syndrome (author's transl)

One hundred and sixty-five EEGs were analysed from 140 patients in postraumatic coma with secondary traumatic midbrain and bulbar syndrome. The EEG-pattern was related to the stage of midbrain of bulbar syndrome caused by supratentorial brain shift. There was a close relation between EEG-pattern and the grade of rostro-caudal impairment. A decrease in the number of different EEG-patterns was associated with increasing intra-cranial pressure. An unfavourable state of coma was indicated by the disappearance of sleep or sleep-like activities, alternating pattern and loss of reactivity. In deep stages of coma the neurological examination reveals no lateralizing signs at all. The EEG gives the only hint to a local cerebral lesion. EEG-abnormalities due to the herniation itself interferred with the EEG-changes due to secondary circulatory, respiratory and metabolic encephalopathies. In such cases the above mentioned regularities were blurred.     

"Theta pattern coma" occurring in younger adults

Since our previous report, where "theta pattern coma" was described in 2 elderly patients as an EEG pattern with a grave prognosis, we have had the opportunity to see another 9 affected patients. In this article, 3 men with a mean age of 36 years who died after cardiorespiratory arrest presented a "theta coma pattern." The EEG activity was initially reactive to and attenuated by external stimulation in 2, but prior to death the pattern became arreactive. This article shows that "theta pattern coma" is not an age related phenomenon as previously considered. So far, 11 patients with this type of EEG abnormality have been seen in our department; all have died, and all were over 30 years of age. An expanded definition of "theta pattern coma" is given in the discussion. The pathophysiological mechanisms involved in generation of this abnormality are not known. This abnormality, when seen in the unconscious patient, should be classified as a grade 4 abnormality on the EEG coma scale and should be differentiated from rather diffuse theta activity in coma. The prognostic significance of "theta pattern coma" appears to be similar to that of "alpha pattern coma."     

Prognostic value of EEG in post-anoxic coma after cardiac arrest

The authors themselves studied 26 patients. The EEGs were classified in terms of increasing severity in 5 categories. Incorporating over 400 cases from the literature, the authors correlated the initial EEG findings with the clinical outcome following cardiac arrest. Grade I EEG findings (normal alpha with theta-delta activity) imply a very good prognosis. A complete remission can be expected in most cases. Grade II (dominant theta-delta activity with detectable normal alpha) and grade III (dominant theta-delta activity without detectable normal alpha) findings have no definite prognosis. Grade IV [low-voltage delta, possibly with short isoelectric intervals; dominant, monomorphic, non-reactive alpha-activity (alpha coma); periodic generalized phenomena (spikes, sharp waves, slow waves with very low background activity)] and grade V (very flat to isoelectric EEG) findings have a very serious prognosis.     

Epileptiform discharges in presence of continuous background activity in anoxic coma

The EEGs of a group of patients in anoxic coma following cardiorespiratory arrest were retrospectively studied. Twelve of 70 patients had at least one EEG recorded during the acute period which consisted of epileptiform discharges in the presence of continuous diffuse background activity. Nine of the patients died while three made a generally favorable recovery. The analysis confirms the prediction of a recent revision of EEG grades in coma that this particular pattern of activity is of uncertain prognostic significance. This is in contrast to the occurrence of epileptiform discharges during discontinuous "burst suppression" activity which generally indicates a fatal outcome.     

An electroencephalographic study of psychiatric inpatients with antipsychotic-induced tardive dyskinesia

The awake EEGs of 48 psychiatric inpatients with tardive dyskinesia were compared with those of 29 matched controls without TD. EEGs of the TD patients were as follows: 22 (45.8%) were normal EEGs; 17 (35.4%), mildly abnormal EEGs; 8 (16.7%), moderately to severely abnormal EEGs. One record was excluded for severe artifacts. The control group showed a similar incidence of EEg abnormalities. EEGs with poor occipital alpha rhythm were significantly more frequent in the TD group than the control group. The TD patients tended to have an alpha rhythm of low voltage. Other characteristics of the alpha rhythm and amounts of theta, delta and beta activity showed no significant differences between the two groups. Severity of TD had no significant influence on EEG findings. The EEG similarities of TD and Huntington's chorea were discussed, and a suggestion was made that not only the basal ganglion, but also the cerebral cortex, could be involved in development of TD.     

The E.E.G. in methylmalonic acidaemia (author's transl)

The EEG study was carried out on 8 cases of methylmalonic acidaemia, in the neonatal period (3 cases), developing later with a ketotic coma, hyperglycinemia, hyperammonaemia, leucopenia and thrombocytopenia (3 cases) and detected before birth (2 cases). The tracings of the neonates in the first group had a periodic appearance. The 2 children detected pre-natally had essentially normal EEGs bar a slightly faster rhythm. The tracings of the children in ketotic coma were similar to those seen in metabolic coma of other cause. The value of this study was, besides characterizing the EEC pattern which resembled that seen in other metabolic illnesses in the neonatal period, to study the changes in the EEG trace and their improvement during dialysis treatment. In one case recordings were made throughout the duration of dialysis.