To the Editor:—A recent review of the clinical uses of propofol [1] prompted us to call attention to yet another application of this drug: propofol sedation for diagnostic and exploratory neuropsychiatric examination.
We were consulted on the case of a 22-yr-old woman who had been admitted after an assault that left her unable to move her legs. She was alert although mildly intoxicated and was capable of slight flexion of her right hip, with no movement on the left side and no perception of pinprick below the level of 1.1. A noncontrast computed tomography scan, a myelogram, and a magnetic resonance imaging scan of the spine revealed no bony fractures or dislocations, free passage of dye in the lower spinal fluid, and no extrinsic or intrinsic lesion of the spinal cord.
Initially, the patient was treated with a large dose of steroids, with a working diagnosis of paraplegia due to spinal cord contusion, and over the next 24 h, there was minimal improvement. Some anomalous findings appeared in her examination however. Her sensory level descended to mid-thigh but then was found to have a nondermatomal distribution. She also had preserved reflexes in both lower extremities. She had normal rectal tone and was voiding without difficulty. Her neurologic examination results remained stable for the next week, and tests of somatosensory evoked potentials and electromyograms had normal results.
This patient's differential diagnosis now included paraplegia due to cord contusion and a conversion reaction. The inconsistency of her neurologic findings and the emergence of some specific psychologic (affective) issues lent strength to a diagnosis of conversion reaction, and lack of improvement mandated exploration.
The neuroanesthesia service was consulted for help in conducting an evaluative neuropsychiatric study with sedation. This was planned to include three examinations, each comprised of an abbreviated mental state examination with relevant tests of motor and sensory functions, to be performed before, during, and after recovery from a sedative.
Propofol was suggested as the agent of choice because of its easily titrated rapid action and recovery with minimal residua. The effect of libidinal disinhibition, which is sometimes associated with this drug, also was discussed. [2] Although this was not considered a contraindication to its use, there was some interest in whether, if propofol were found particularly effective in this setting, it could have some bearing on the historic perception of conversion reactions as being libidinally based. [3].
After discussion with the patient, informed consent was obtained for the procedure. Monitoring included electrocardiogram, pulse oximeter, and noninvasive blood pressure (Dinamap). Oxygen was administered with nasal cannula at the rate of 2 l/min to maintain normal oxygen saturation, and a peripheral intravenous line was inserted through a 20-G cannula.
After a baseline neuropsychiatric examination, propofol was infused at the rate of 300 micro gram *symbol* kg1*symbol* min1until deep sedation was achieved. At this point, the infusion was discontinued and, as soon as feasible, the second examination conducted. While still under the influence of propofol and in a hypnotized-like state, the patient's sensorimotor examination had improved significantly. With verbal encouragement, she was able to stand and take several steps, and her sensory level had descended from mid-thigh to mid-calf. In a few minutes, while resting in bed, she regained her normal state of alertness, and the third and final neurologic examination was performed. She again had lost much of her quadriceps power, although there was some minor improvement from her baseline performance. Her sensation was improved by descending about 10 cm down her left leg, maintaining its nondermatomal distribution. She had no recollection of the events during this evaluation, and she immediately asked the neurologist and neurosurgeon about the results of the test. She was given positive feedback.
The evaluations in this study were performed by a neurologist, a neurosurgeon, and a psychiatrist who were present throughout. In subsequently reviewing the results and drawing conclusions, their opinions were sought concerning observable differences resulting from the use of propofol compared with their prior experience of amobarbital sodium during this type of examination. There was agreement that the study benefitted from her faster recovery from propofol than had been seen in similar examinations using barbiturates, making comparison between the three phases of the examination simpler.
We suggest that propofol offers an alternative to barbiturates during the conduction of neuropsychiatric evaluation with sedation. Although further evaluation is required and awareness of its potential for libidinal disinhibition should be considered, this agent is a reliable, widely used anesthetic agent that is easy to titrate and safe when used with available respiratory support. The rapid return of the presedation state of alertness with propofol use is advantageous in that it provides the conditions for a valid examination at completion of the study.
David Ferson, M.D., Assistant Professor of Anesthesiology.
Irene Osborn, M.D., Assistant Professor of Anesthesiology, Department of Anesthesiology, Montefiore Medical Center, 141 East 210th Street, Bronx, New York 10467.
Robert Soper, M.D., Fellow in Clinical Genetics, Department of Genetics, Yale University Medical School 333 Cedar Street, New Haven, Connecticut.
(Accepted for publication January 23, 1995.)
