Dwight Parkinson

Leukocytosis and subarachnoid hemorrhage

We present a study of the white blood cell count at time of admission in patients with spontaneous subarachnoid hemorrhage. A nearly normal white blood cell count has little correlation with either the clinical grade at time of admission, or with the patients ultimate outcome. A white blood cell count exceeding 20,000, however, is associated with poor clinical grade on admission and with a 50% mortality.

Lateral sellar compartment O.T. (Cavernous Sinus): History, anatomy, terminology

Claudios Galen (119–199 a.d.) dissected lower animals with parasellar carotid retia bathed in venous blood and transposed his findings to human anatomy. Andreas Vesalius (1514–1564) corrected most of Galens errors but apparently never looked into this small, extradural compartment, nor, apparently, did Winslow (Exposition Anatomique de la Structure du Corps Humain. London: N. Prevast, 1734), who christened it the “cavernous sinus,” (CS) presumably thinking that it would resemble the corpora cavernosa of the penis. Multiple surgical explorations, gross dissections, microscopic views, and vascular casts from early fetuses to an 81 year old have been examined and reviewed. The CS is not a dural sinus nor is it cavernous. The compartment is extradural, and the venous structures contained within consist of a greatly variable plexus of extremely thin‐walled veins. The name, CS, is a barrier to the understanding of the structure and function of this extradural anatomical jewel box, which contains fat, myelinated and nonmyelinated nerves, arteries, and a plexus of veins. It is proposed that this name be changed, because it is inaccurate and misleading. The replacement should leave no doubt about its meaning. The lateral sellar compartment is descriptive and accurate. The veins within are a parasellar plexus. Anat. Rec. 251:486–490, 1998.

Cerebral concussion in rats rapidly induces hypothalamic-specific effects on opiate and cholinergic receptors

Conscious male adult rats were concussed by a blow to the occiput with a blunt dart, shot from a spring-loaded pistol. Animals were decapitated within 2 sec, brains quickly removed, several brain regions homogenized in cold buffer and radioreceptor assays carried out. There was a 20% increase in binding of [3H]naloxone and [3H]QNB in the hypothalamus but not in the amygdala, striatum, hippocampus, cortex, midbrain and hindbrain. For animals killed 5-10 sec after concussion, when normal conscious behavior had returned, there were no changes in binding between control and concussed rats. Binding of [3H]spiroperidol and [3H]ouabain was unaffected by concussion. To rule out changes due to non-specific stress, one series of rats received a blow to the lower body. There was no change from control in [3H]QNB binding to hypothalamic tissues by a body blow as compared with the blow to the head. The findings suggests decreased binding of endogenous endorphins and acetylcholine to their respective receptors as a result of concussion. The transient deficit in endogenous transmitter binding may temporarily interrupt hypothalamic circuits concerned with the state of consciousness.

Spinal Cord Concussion

A reliable experimental model using decerebrate frogs has been developed by which a measured cutaneous stimulus to the right forelimb produces a single electrical response from the left sciatic nerve. Using this model, the minimal concussing force necessary to abolish the propagation of the nerve impulse down the spinal cord was established by trial and error. The mean recovery time was 31.2 seconds, with a standard deviation of 1.32 seconds. Recovery of function of the spinal cord, as measured this method, was complete following single and multiple concussions.

Neurochemical effects of static magnetic field exposure

BACKGROUND There has been considerable interest in both the lay and scientific media concerning the putative effects of exposure to electromagnetic fields. An assessment of the effects of static magnet exposure on neurochemistry was undertaken to determine potential risks to patients and staff involved with magnetic resonance imaging and spectroscopy. METHODS One set of rats were exposed to weak static field (800 gauss [G]) in an otherwise normal laboratory surrounding. Another set of rats were exposed to 7-Tesla fields, both with suitable controls. RESULTS Exposure of rats (n=8) to weak static fields for periods between 12 hours and 8 days produced no significant change in nighttime pineal or serum melatonin levels, as compared to controls, nor did it significantly influence levels of pontine medullary 5-hydroxytryptamine [5-HT] and hypothalamic 5-hydroxyindoleacetic acid [5-HIAA]. Placing rats in a 7-Tesla MRI magnet for 45 minutes produced similar results. CONCLUSIONS These experiments suggest that daily light/dark cycle has much greater influence on levels of melatonin, catecholamines, serotonin, or their metabolites than does exposure to a static magnetic field.

Spinal-cord concussion in frogs: a study of reflex changes

A reliable experimental model of the spinal frog, employing the flexor withdrawal reflex to a noxious stimulus, has been used to study the response to single and repeated concussing blows over the spinal column. It is evident that caudally placed blows depress the reflex response, whereas more cephalad blows facilitate the response. The results of studies using repeated concussing blows support the concept that neuronal units may completely lose their function without suffering permanent structural damage.

Evaluating cerebral concussion

Years ago we developed a rat model that was consistently comatose for 1-2 seconds following 50 G acceleration of the head. Motor normalcy returned in about 10 seconds, and normal memory in an hour. There were immediate electroencephalogram and transmitter changes. All these returned to normal within an hour following 1 or 20 such concussions. We could find no light or electron microscopic changes. Halothane anesthesia precludes measurement of coma and introduces distortion of metabolite findings. To date our findings indicated concussion at this level is completely reversible.

Posterior “septum” of human spinal cord: Normal developmental variations, composition, and terminology

The boundary separating the posterior columns of the spinal cord is formed by the lateral margins of the neural groove approximating to form the neural canal. In anatomy texts this line is usually drawn as continuous, uniform, centered, and straight. It is universally termed posterior or dorsal, median “septum.”

Changes in hippocampal monoamine concentration following halothane anesthesia and concussion

The concentration of norepinephrine in the hippocampus of rats anesthetized with halothane (Wyeth-Ayerst, Philadelphia, Pa) is found to be markedly increased, presumably due to the stress of handling and administering the anesthetic. This increased norepinephrine concentration persists for about 50 minutes but is obliterated when the anesthetized rat is concussed. This 50-minute period corresponds to the time it takes for a rat (or human), comatose for 1-2 seconds following concussion, to regain normal memory. No changes in 3,4-dihydroxybenzene-acetic acid (DOPAC), 3-(3,4-dihydroxyphenyl) alanine (L-DOPA), and 3,4-dihydroxybenzylamine (DHBA) were noted. 5-Hydroxy indole acetic acid (HIAA) showed a depression at 5 minutes and again at 30 minutes, changes that were consistent but not considered statistically significant.

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