Magnetoencephalographic Infraslow Activity: A Feasibility Study.

PURPOSE: To explore if background infraslow activity (ISA) can be retrieved from archived magnetoencephalographic (MEG) recordings and its potential clinical relevance. METHODS: Archived recordings of 15 patients with epilepsy and 10 normal subjects were evaluated for MEG/EEG delta (0.5-3 Hz) and ISA (0.01-0.1 Hz). The data were obtained on a Neuromag/Elekta system with 204 planar gradiometers and 102 magnetometer sensors and also 60 EEG channels. To remove artifacts, all MEG files were temporal signal space separation filtered. The data were then analyzed with the BESA Research software. RESULTS: Infraslow activity was present in all files for MEG and EEG. Good concordance between EEG and MEG ISA was seen with delta for laterality and with clinical features. Delta frequencies were always less than 2 Hz. During sleep, an inverse relationship between delta and ISA occurred. With increasing depth of sleep, delta activity increased while ISA decreased and vice versa. Intermittent higher amplitude transients, arising from background, were also seen but their nature is at present unknown. Clinically relevant ictal onset baseline shifts were likewise observed. CONCLUSION: Infraslow activity is a normal segment of the cerebral electromagnetic frequency spectrum. It follows physiologic rules and can be related to areas of pathology. This is in accord with previously published EEG observations and further studies of this segment of the electromagnetic frequency spectrum for its origin and changes in health and disease are indicated.

The skull and cervical spine radiographs of Tutankhamen: a critical appraisal.

BACKGROUND AND PURPOSE: Tutankhamen, the last pharaoh of the XVIIIth dynasty, died unexpectedly at approximately age 18 years. A cause of death has never been established, but theories that the young king was murdered by a blow to the head have been proposed based on skull radiographs obtained by a team from the University of Liverpool in 1968. We recently had the opportunity to evaluate the skull and cervical spine radiographs of Tutankhamen. The purpose of this study was to report our critical appraisal of the radiographs of Tutankhamen regarding the findings alleged to indicate traumatic death. METHODS: Copies of lateral, anteroposterior, and submental vertex skull radiographs of Tutankhamen were reviewed with special attention to the claims of a depressed skull fracture, intracranial bone fragments, and calcified membrane of a posterior fossa subdural hematoma. A phantom skull was radiographed to reproduce the appearance of the floor of the posterior fossa in the lateral projection. RESULTS: The skull radiographs of Tutankhamen show only postmortem artifacts that are explainable by an understanding of the methods of mummy preservation used at the time of his death. Some findings also relate to trauma inflicted by an autopsy performed in 1925. The alleged calcified membrane of a posterior fossa subdural hematoma is easily reproduced with a skull phantom. CONCLUSION: Our critical review of the skull and cervical spine radiographs of Tutankhamen does not support proposed theories of a traumatic or homicidal death.