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V M Synek

Publications and source records attributed to V M Synek.

At least 19 recordsLinked to original sources
PubMed1991

Important abnormalities in recordings of somatosensory evoked potentials in coma.

We have chosen six illustrations showing how much vital information can be obtained from median nerve SEPs during the first 24 hours in coma. With avulsion of brachial plexus roots there was loss of SEPs at the cervical cord and the scalp from the affected side. In a severe injury of the cervical cord there was preservation of brachial plexus potentials, while SEPs at the cervical cord were absent. After critical deterioration in a case of repeated subarachnoidal hemorrhage, scalp SEPs with very short latency occurred, which is a finding suggestive of destruction of cortical SEP generators heralding a fatal outcome. In a case of brain injury combined with central hyperthermia, there was initially a loss of scalp SEPs probably due to the combined effect of these factors. In a case of brain injury there were bifid peaks at the scalp level. It is important to assess central sensory conduction time only to the first scalp SEP, otherwise an erroneously abnormal state may be inferred. In a patient with clinical and EEG evidence of brain death there was a loss of far-field thalamic potentials at the neck. It is important to be aware of such presentations to be able to provide corroborative assurance for the assessment of prognosis.

Adult↗
PubMed1991

Re: EEG in coma.

Explore the source record for details and available documents.

Coma↗
PubMed1990

Value of a revised EEG coma scale for prognosis after cerebral anoxia and diffuse head injury.

The prognostic validity for survival of a recently devised EEG grading scale was tested in anoxic and post-traumatic coma. This scale divides EEG in coma into five major grades and ten subdivisions with emphasis on the presence of dominant activities, their amplitude, persistence, distribution and reactivity. In this scale, patterns previously not allocated, such as "spindle pattern coma," "alpha pattern coma," and "theta pattern coma" are also included. The prognostic power of the revised scale was tested retrospectively without knowledge of clinical data in a group of patients with cerebral anoxia after cardiac arrest lasting more than seven minutes and in a group of diffuse head injuries. The validity of the scale was found to be higher than those used in previously published studies, reaching 98.4% prognostic accuracy in anoxic encephalopathies and was very high in head injuries.

Coma↗
PubMed1990

Revised EEG coma scale in diffuse acute head injuries in adults.

The validity of a recently published EEG grading scale applied to patients with acute head injuries has been investigated. This scale is based on 15 individual grades and subdivisions and 3 major groups: 4 patterns are benign regarding survival, 4 are of uncertain significance and 7 patterns are prognostically malignant. The evaluation was performed in 90 adult patients with acute head injuries in whom EEGs obtained during the 36 hours after the injury were evaluated retrospectively without knowing the clinical details or the outcome. By employing previously reported definitions it was possible to allocate EEG abnormalities in all cases. The assumption was made that at the time of the EEG investigation the impact of the head injury on cerebral function was already established. All patients displaying 'benign' patterns survived. 'Uncertain' patterns were the most common ones and in patients with these the reactivity of EEG activity was more important for prognosis than the quality of the background activity. All but 3 of the patients with a 'malignant' pattern died, and the survivors remained in a vegetative state. There was a correlation between the EEG findings and the Glasgow Coma Scale score on admission and also with the results of computerized tomography of the brain. In those patients who died there was no significant relationship between EEG signs and autopsy findings. Repeated EEGs are always desirable with severe head injuries but the results of this study suggest that useful prognostic information can be obtained from an EEG recorded within 36 hours after the head trauma.

Adolescent↗
PubMed1989

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.

Aged↗
PubMed1989

Validity of a revised EEG coma scale for predicting survival in anoxic encephalopathy.

A revised EEG grading scale in coma has been introduced previously. This scale is based on the internationally accepted 5 grade scale but also contains uncommon patterns such as spindle, alpha and theta pattern comas. By defining 15 separate grades and subgrades it was possible to reduce the number of patterns of uncertain prognostic significance for survival to 4 out of the 15 possible patterns. It is also hoped that by a clear definition of individual grades and subdivisions the scale will assist electroencephalographers who lack experience of coma cases. The validity of the scale has been tested in a group of 63 patients who suffered cardiac arrest in excess of 7 minutes' duration. The EEG was performed 24 to 36 hours after the onset of coma. The accuracy of prediction for survival was 98.4%, a rate higher than in previously published studies. The mortality rate was 70%, 19 patients surviving. There was a statistically significant correlation between mortality rate and duration of cardiac arrest and also between mortality rate and increasing age. Four suggested scale subdivisions did not occur in the material studied but these subdivisions are more common in traumatic encephalopathies. This study shows that an EEG performed 24 to 36 hours after cardiac arrest provides significant information for the prediction of survival. No specific patterns of microscopic changes in the brain were found to correlate with individual EEG abnormalities in fatal anoxic encephalopathies.

Adult↗
PubMed1988

Origin of reprint requests.

One thousand consecutive reprint requests were classified according to their countries of origin. One third came from the United States of America and over 70% originated in six countries (USA, Czechoslovakia, France, West and East Germany and Canada). When reprint requests were adjusted for population size, a different order became apparent with Czechoslovakia requesting proportionally the most, followed by Israel, East Germany, Canada, Switzerland and Belgium. Approximately half of the reprint requests came from European countries with the overall rates for western and eastern European nations being similar. There were comparatively few requests received from Third World nations. The analysis questions several of the reasons commonly given for honouring reprint requests.

Humans↗
PubMed1988

Prognostically important EEG coma patterns in diffuse anoxic and traumatic encephalopathies in adults.

Because of the paucity in the English literature of a detailed and universally accepted EEG grading scale relating to survival after diffuse traumatic and anoxic brain insults, prognostically oriented EEG patterns including recently described abnormalities are presented and discussed. The significance of these patterns may also apply in cases of coma of other etiologies, which can present morphologically similar features. EEG patterns have been classified into five major grades based on an internationally accepted scale. Individual patterns have been more clearly defined on the basis of the morphology of dominant activities, their distribution, persistence, and reactivity to external stimulation. Favorable outcome with survival seems to occur with both grade 1 and the "reactive type" of grade 2 abnormalities, with preservation of normal sleep features, and with frontal monorhythmic delta activity. Prognostically uncertain patterns are "nonreactive" grade 2 abnormalities, diffuse delta activity with grade 3 abnormality, and the "reactive type of alpha pattern coma." The following patterns are suggested to be prognostically malignant if persistent: grade 3 abnormality with small amplitude, diffuse, irregular delta activity; grade 4 ("burst suppression pattern"), in particular when epileptiform discharges are present and with "low-output EEG"; and grade 5 ("isoelectric EEG"). Fatal outcome is also common with the "nonreactive type of alpha pattern coma" and the recently reported "theta pattern coma." These patterns are presented in the illustrations. It is intended that this more detailed subdivision will promote understanding between electroencephalographers using visual EEG assessment in cases of coma.

Brain Damage, Chronic↗
PubMed1988

Interside amplitude asymmetries in the median nerve somatosensory evoked potential: normative data.

Short latency median nerve somatosensory evoked potentials (SEPs) were recorded from a group of 31 adults in order to establish the boundaries between normal and abnormal interside amplitude asymmetries. The potentials studied were the cervical SEP (N13) and the primary cortical response (N20). In order to more accurately analyse and compare intersubject data, the amplitude of the lesser potential was expressed as a percentage of the greater potential. The limit for normality was defined as 1 SD (of the mean amplitude asymmetry) below the lowest individual value observed among normal subjects. It is concluded that if a cervical potential from one side is no more than 60% of the potential from the other side, then this represents a significantly abnormal amplitude asymmetry. In contrast, a cortical potential must have an amplitude which is less than 36% of the larger potential in order to be considered significantly abnormal.

Adolescent↗
PubMed1988

Unusual scalp recorded somatosensory evoked potentials after removal of a large intraventricular meningioma.

Very unusual scalp recorded SEPs were seen in a case after removal of a large intraventricular meningioma. One day before death (ten days after surgery) when the patient was moribund, SEPs from the clinically and radiologically affected hemisphere in which a hematoma and thalamic infarct were found, had a normal latency and were decreased in amplitude. SEPs from the clinically and radiologically nonaffected hemisphere, where only minimal findings were seen, had an abnormally short latency (16.9 msec) and the CCT was only 3.1 msec. We do not offer any logical explanation of these unusual SEP findings from both hemispheres shortly before death.

Cerebral Ventricle Neoplasms↗
PubMed1988

EEG abnormality grades and subdivisions of prognostic importance in traumatic and anoxic coma in adults.

The EEG has long been established as an important laboratory test when assessing cerebral function in comatose states. During the last three decades, several grading scales regarding severity of the EEG abnormality in coma have been suggested to increase the prognostic power of the EEG for survival. Their main limitation was, that the majority of EEG abnormalities in coma fell in the middle of the five point scaling systems, i.e. Grade 3 abnormality on the five grade abnormality scales. In addition, it was considered that non-reactivity of EEG pattern in coma is confined only to the most advanced grades. The purpose of the present article is to define precisely the main five abnormality grades and their subdivisions, and to allocate them in five principal categories regarding their significance for survival. The five categories are: 1 = optimal, 2 = benign if persistent, 3 = uncertain, 4 = malignant if persistent, and 5 = fatal unless caused by drug effect or hypothermia. After the inclusion of more recently described coma patterns, it was possible to outline prognostic significance for survival in eleven types of abnormalities with assurance. Only four remain of uncertain prognostic significance. The EEG abnormalities as discussed in this article are generally applicable only to coma after diffuse brain trauma and cerebral hypoxia. However, they may also be found in some other diffuse encephalopathies associated with coma.

Alpha Rhythm↗
PubMed1988

Transition from alpha to theta pattern coma in fatal cerebral anoxia.

A transition of alpha to theta pattern coma is documented in a case of fatal cerebral anoxia after a cardiac arrest. The patient was a 35-year-old woman who suffered a cardiac arrest due to myocardial ischaemia and ventricular tachycardia. Altogether 6 EEGs showing progressive deterioration were performed during the 11 days of survival. There was histopathological evidence of extensive ischaemic damage involving cerebral and cerebellar cortex, basal ganglia and brainstem structures. Although closed chest cardiopulmonary resuscitation was begun with minimal delay after cardiac arrest, the outcome may reflect the increasingly documented failure of this type of resuscitation to provide adequate organ perfusion during cardiac arrest.

Adult↗
PubMed1987

Intersession stability of somatosensory evoked potentials.

Upper and lower limb nerve somatosensory evoked potentials (SEPs) were recorded from a group of normal adults in order to assess their intersession stability. Median, peroneal and sural nerve SEPs were recorded from each subject on 3 successive occasions at weekly intervals. For median nerve SEPs, the intrinsic variability was more pronounced for interpeak latencies (N9-N20, N13-N20) than for the latencies of individual components. Their inherent fluctuation was not, however, notably greater for the primary cortical response (N20) than for the more caudally generated components (N9 and N13). These relationships were not so apparent for lower limb SEPs where intersession variability was markedly greater overall than for upper limb SEPs.

Adolescent↗
PubMed1987

Role of somatosensory evoked potentials in the diagnosis of peripheral nerve lesions: recent advances.

Short-latency somatosensory evoked potentials (SEPs) have become an important tool in the investigation of peripheral nerve lesions. Electrically evoked SEPs are most suitable because they provide results with small variations and are readily repeatable. Techniques for testing 10 different upper and lower limb nerves, dermatomes, cutaneous fibers of trigeminal nerve, and nerves supplying urogenital areas are now available. The established, principal areas of application are in the investigation of brachial plexus lesions, proximal injuries of individual nerves in upper and lower limbs, and painful dysesthesias and in the differential diagnosis of pain caused by psychogenic causes or organic lesions. The techniques have proven to be of value in demonstrating early proximal abnormalities in polyneuropathies. Abnormalities have occurred in trigeminal nerve lesions, urogenital dysfunctions, hereditary ataxias, and rare neuropathies. Unexpected abnormalities have also been reported in motor neuron disease, myotonic muscular dystrophies, and other conditions. Applications in the diagnosis of spondylopathic root lesions are not satisfactory; the techniques' usefulness in the investigation of these lesions does not extend beyond aiding the selection of patients for other diagnostic modalities, such as myelography, computed tomography (CT), and nuclear magnetic resonance (NMR) imaging. The usefulness of SEP techniques in the diagnosis of peripheral nerve lesions will remain, even if advances in organ imaging techniques can provide more specific information about the level and magnitude of lesions in the central nervous system. SEP techniques are an important complement to the other well-established methods, such as clinical testing, electromyography, and nerve conduction studies.

Evoked Potentials, Somatosensory↗
PubMed1987

"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."

Adult↗
PubMed1987

The pyriformis syndrome: review and case presentation.

The pyriformis syndrome is a rare entrapment neuropathy in which the sciatic nerve is compromised by the pyriformis muscle or other local structures. It usually presents with sciatic pain and hypoaesthesia and a limp caused by weakness of the gluteus maximus muscle. Peroneal nerve innervated muscles and hamstrings are also usually affected. The diagnosis relies on the clinical presentation and the EMG findings. Other causes of symptoms should be excluded by careful examination, detailed x-ray studies of the lumbosacral spine (including myelogram), sacro-iliac and hip joints. A case of this syndrome occurring in a previously healthy 42 year old woman and her follow-up investigations are reported.

Adult↗