A preliminary MRI study of the geometry of brain displacement and level of consciousness with acute intracranial masses

Abstract

We determined the horizontal and vertical components of brain displacement on coronal MRIs in 10 patients with acute supratentorial masses. The vertical distances from the superior sagittal sinus to the pontomesencephalic junction (PMJ) and from the vertical midline of the brain to the PMJ did not differ from measurements in 30 patients without masses. Horizontal displacement of the 3rd ventricle (mean, 5.2 mm) exceeded vertical displacement of the PMJ (mean, 1.2 mm) in all but 1 patient. Total brain displacement near the incisura increased from 3 mm in awake patients to 6 to 13 mm in stuporous and comatose patients and remained predominantly horizontal. Uncal herniation, seen only in a patient who was imaged a day after the onset of coma, did not appear to be the immediate cause of brainstem compression but was accompanied by prominent lateral distortion above the tentorium. This preliminary study suggests that most patients with acute unilateral masses have upper brainstem distortion due predominantly to horizontal shift at or above the tentorium.

Early clinical differentiation of cerebral infarction from severe atherosclerotic stenosis and cardioembolism.

“…Loss of consciousness has been reported to be more frequently associated with a cardioembolic stroke than with other types of infarctions. 1617 Recent studies of patients with decreased consciousness by CT scan 18 and MRI 19 have suggested that horizontal displacement of the brain above the tentorium is closely related to impairment of alertness. Because infarcts are slightly larger and probably more inferiorly located in EMB than in ATH, the lateral shift may be greater and could account for the increased frequency of decreased consciousness.…”

Diagnostic Accuracy of Transcranial Doppler for Brain Death Confirmation: Systematic Review and Meta-Analysis

“…The classic neurologic injury leading to brain death is a supratentorial mass lesion with downward herniation into the brain stem. 49 Because herniation continues due to increased intracranial pressure, cerebral perfusion will wane and finally be absent, resulting in CCA and corresponding TCD waveforms. Other etiologies that result in global cerebral edema (diffuse anoxic brain injury, leukoencephalopathy from toxin ingestion, poor-grade subarachnoid hemorrhage, and diffuse traumatic brain injury) will also lead to refractory intracranial pressures and CCA whose waveform patterns can be detected by TCD.…”

Sonographic Monitoring of Midline Shift in Space-Occupying Stroke

“…[5][6][7][8] Lateral displacement of midline structures resulting from progressive postischemic edema has been found to correlate closely with a poorer outcome in stroke patients. 5,7,9,[10][11][12][13][14] In a subgroup of stroke patients with rapid progressive edema, the mortality rate reaches 80% as the result of axial brain stem herniation. 15,16 Several open, prospective studies indicate that decompressive hemicraniectomy can decrease mortality rates up to 50% in so-called "malignant" middle cerebral artery (MCA) stroke, that is, postischemic edema unresponsive to treatment.…”