Electroencephalographic correlates of lateral dislocation in acute cerebral insufficiency

BACKGROUND: Dislocation syndrome is characterized by a displacement of the median structures in brain and is a consequence of a progressive increase in intracranial volume in vascular accidents, traumatic brain injury, and neoplasms. Lateral dislocation of the median structures leads to their gross dysfunction, as well as to compression of the cortical sections, which leads to violations of the mechanisms of generation of bioelectrical activity. In acute cerebral insufficiency in conditions of scarcity of clinical symptoms, the analysis of changes in the bioelectrical activity of the brain becomes an important part of the diagnosis and prognosis of the course of a critical condition.

AIM: The aim of this study is to characterize the electroencephalography (EEG) patterns recorded in patients with lateral dislocation in the acute period of traumatic brain injury and hemorrhagic stroke.

MATERIALS AND METHODS: The work was based on the analysis of the EEG amplitude-frequency parameters recorded in 74 patients (52 men, 22 women, mean age 53.3 ± 12.5 years) who were treated at the Dzhanelidze Research Institute for Emergency Medicine. The cause of acute cerebral insufficiency in 42 cases was a traumatic brain injury, in 32 cases — a hemorrhagic stroke. Inclusion criteria: 1) lateral dislocation more than 4 mm according to the results of computed tomography; 2) level of consciousness Coma 1 or Coma 2; 3) the outcome of the disease was determined within 23 days from the moment of injury or stroke. 24 observations had a favorable outcome.

RESULTS: According to the results of computed tomography, lateral displacement of the brain structures (Me 9 [6; 16] mm) was revealed in all patients, but without signs of their compression or infringement. Recorded EEG variants were divided into three groups: 1) focal and diffuse disturbances without signs of persistent epileptiform activity of a high index (30%); 2) dominance of gross epileptiform disorders included in the syndromic structure of non-convulsive status epilepticus (59%); 3) isoelectric “silence” of the brain (11%). The degree of lateral dislocation reached its maximum values when registering the bioelectric “silence” pattern. With a favorable outcome of acute cerebral insufficiency, there was practically no correlation between the severity of EEG disturbances and the degree of dislocation. With unfavorable outcomes, dislocation syndrome was a factor that determined the severity of EEG disturbances (r = 0.36). An analysis of the distribution of favorable and unfavorable outcomes showed that the formation of non-convulsive status epilepticus complicates the course of acute cerebral insufficiency, but is not an unambiguous predictor of an unfavorable outcome (χ² = 0.589, p = 0.44).

CONCLUSIONS: Thus, the bioelectrical activity of the brain recorded in patients with acute cerebral insufficiency complicated by lateral dislocation, reflects both general cerebral and focal changes. In 60% of patients with lateral dislocation of the midline structures of the brain on the EEG, patterns are formed corresponding electrographic patterns of nonconvulsive status epilepticus.