ABSTRACT
RATIONALE: Imaginative suggestibility, a trait closely related to hypnotic suggestibility, is modifiable under some circumstances. Nitrous oxide (laughing gas) is commonly used for sedation in dentistry and is reported to be more effective when combined with appropriate suggestions. OBJECTIVE: The aim of this study was to determine whether nitrous oxide inhalation alters imaginative suggestibility and imagery vividness. METHODS: Thirty participants were tested twice in a within-subjects design, once during inhalation of 25% nitrous oxide and once during inhalation of air plus oxygen. Before the study, participants' expectancies regarding the effects of nitrous oxide were assessed. Participants were blinded to drug administration. During each session, participants were verbally administered detailed measures of imagination and suggestibility: the Sheehan-Betts Quality of Mental Imagery scale and the Stanford Hypnotic Susceptibility Scale Form C, minus the hypnotic induction. RESULTS: Imaginative suggestibility and imaginative ability (imagery vividness) were both elevated in the nitrous oxide condition. This effect was unrelated to participants' expectations regarding the effects of the drug. CONCLUSIONS: Nitrous oxide increased imaginative suggestibility and imaginative ability. Possible explanations of these findings are discussed with respect to the effects of N-methyl-d-aspartate antagonists and to other pharmacological effects upon suggestibility and imagination.
Subject(s)
Anesthetics, Inhalation/pharmacology , Hypnosis , Imagination/drug effects , Nitrous Oxide/pharmacology , Administration, Inhalation , Adult , Dose-Response Relationship, Drug , Female , Humans , Male , Receptors, N-Methyl-D-Aspartate/antagonists & inhibitors , Single-Blind Method , SuggestionABSTRACT
Proton magnetic resonance imaging (MRI) examinations were performed in six patients with seven acoustic neuromas, and the results were compared with conventional tomography of the internal auditory canals, contrast-enhanced computed tomography (CT), and air CT cisternography. All tumors were identified with MRI. The three largest tumors (greater than 1 cm diameter) looked similar to the tumors seen on CT scans, although the extent of the tumor was better seen with MRI in two cases. The four small (less than or equal to 1 cm diameter) cerebellopontine angle and intracanalicular tumors were well seen with MRI, with appearances corresponding to those seen with air CT cisternography. No side effects were encountered with the MRI examinations. MRI is an accurate, noninvasive alternative to contrast-enhanced CT and air CT cisternography in the diagnosis of acoustic neuromas.
