E. S. Gurdjian

The Mechanism of Skull Fracture

Deformation patterns of the skull due to blows of low velocity, as well as the mechanism of production of linear skull fracture, have been previously described (1–5). When the dry skull is coated inside and out with “stresscoat” brittle lacquer, and then subjected to a blow, the lacquer cracks in the areas of greatest tensile deformation. The cracks appear on the outside of the skull in the regions in which the bone bends outward and on the internal surface where the bone bends inward. A region of inbending—generally circular, oval, or star-shaped—always surrounds the point of application of a blow, no matter where it is struck. Where the skull curves sharply, however, the extent of the inbending is not so great as in a less curved region. By means of the “stresscoat” technic, it has been shown that outbending of bone may occur at a considerable distance from the point of application of the blow. In some specimens a contrecoup type of outbending has been observed approximately diagonally opposite the poin...

Studies on mechanical impedance of the human skull: Preliminary report

The steady state vibration response of the human cadaver head across a frequency range including its first three modes of vibration has been studied. Important first and third modes were found near 300 Hz (antiresonance) and 900 Hz (resonance), respectively. Below 200 Hz the skull moved relatively as a rigid body. In the antiresonant mode, maximum mechanical impedance (force/velocity) was found to occur, with acceleration amplification on the occiput greater than frontal input acceleration by a factor of 3. In the resonance mode minimal mechanical impedance occurs in which only that part of the head adjacent to the driven point is moving under the action of a vibratory force. It is hypothesised that long duration impacts (t > 0·005 sec) produce predominantly rigid body motion because the frequency spectrum of the pulse is too low to excite the lowest natural frequency of the skull. Consequently the driving force produces primarily acceleration of the head. Shorter duration pulses, particularly those with short rise time, have a broader frequency spectrum which can excite skull modes, thereby augmenting or modifying the skull flexure patterns produced by the force. It is not yet understood in what proportions these factors influence head injury, but impact head accelerations have been recorded opposite the blow for short duration impacts (t < 0·004 sec) that do not correlate with rigid body acceleration (a = force/head wt.) sometimes being greater by a factor of 2.

Results of Endarterectomy in the Treatment of Cerebrovascular Diseasea

During the past 6 years, 94 patients have been explored in the neck for endarterectomy of the carotid bifurcation and/or the first portion of the vertebral artery., Of these, 16 had a complete occlusion of the internal carotid artery at the time of the endarterectomy, 72 had varying degrees of stenosis of the carotid bifurcation, and 6 were examples of involvement of the first portion of the vertebral artery in which 4 were treated by endarterectomy; endarterectomy was deemed inadvisable at the time of exploration in the other 2 because of the small size of the

Angiography in the evaluation of intracranial trauma.

Angiography in the diagnosis of intracranial lesions is not a new procedure, having been developed in 1927 by Egas Moniz (2). The technic has not been widely applied, however, in the evaluation of intracranial mass lesions occurring as a result of trauma. Many surgeons have preferred to depend upon watchful waiting, with the employment of a trephine as indicated. Under this type of management the diagnostic error has been high (30 to 40 per cent). In an attempt to reduce this figure, we have been utilizing carotid arteriography with increasing frequency since 1949. Approximately 1,000 head injury patients are seen on the neurosurgical services of the Detroit Receiving, Detroit Memorial, and Grace Hospitals each year. About one-half of these present evidence of severe intracranial damage. It is in this latter group that angiography has been useful in determining the presence of intracranial hematoma, its extent, and its localization. In previous reports on this subject, 30 cases studied by angiography were...

The problem of minor and major causalgias

Abstract Thirty-four patients with minor causalgia as seen in civilian life are reviewed. They were predominently men in the fourth and fifth decades. The type of injury varied from minor blows to severe crush injuries. The pain was unusually burning and constant and was associated with vasomotor dysfunction. The patients were treated by various means. Sympathectomy gave relief in most cases, followed by sympathetic ganglion block, local operative procedures and local nerve block in that order of effectiveness.

EVALUATION OF TORTUOSITY OF EXTRACRANIAL VESSELS.

four major vessels supplying the brain. In addition, there were many of these patients who had what appeared to be an abnormally wide carotid bifurcation angle. It was our general impression that arterial tortuosity and a widened carotid bifurcation angle were more common in those individuals with clinically determined cerebrovascular disease. Metz et al.,’ however, in their review of 1000 carotid angiograms concluded that there was no relationship between the severity of kinking, clinical symptoms of cerebrovascular disease, hypertension, or increasing age. It should be noted that their review was limited to angiograms which were otherwise considered normal, and, therefore, may well have excluded those subjects with both a clinical course suggestive of cerebrovascular disease and a significant abnormality on the carotid angiogram ,Uch as vessel occlusion. To determine the relationship between tortuosity of the carotid

Neurosurgical Aspects of Occlusive Cerebral Vascular Disease

The surgeons interest in cerebral vascular disease began in the last century with the concern for hemorrhagic collections on the surface of the brain-the epidural and subdural hematomas. In this century, with the development and use of cerebral angiography since the thirties, cerebral aneurysms and their intracranial complications have gained increasing attention. Of more than academic interest, many aneurysms are now amenable to surgical treatment. More recently, patients having a socalled “cerebral vascular accident,” or “stroke syndrome,” have been referred to the neurosurgeon for evaluation. By collaboration, the radiologist also is involved in seeking a physiologic explanation for the dysfunction associated with cerebral vascular insufficiency and/or failure. Such collaboration is based mainly upon the application of the radiologic technic of angiography. This revealing premortem pathophysiologic roentgen procedure is disclosing new and important information concerning the dynamics of cerebral blood...

Glass electrode measurement of cerebrospinal fluid sodium and potassium

Abstract A routine p h meter and accessories have been modified for measuring sodium and potassium by the glass electrode method. CSF sodium and potassium concentrations measured by both the glass electrode and flame photometer have been compared. The mean concentration of sodium and potassium as measured by the electrode was 143/2.4 and by the photometer, 145/2.7. The average γ csf Na+ + K+ was 0.745. The average aNa+ was 108.03, average aK+, 2.01. The relationship between the concentrations as determined by the electrode and photometer is expressed by the equation Y = 0.888 X + 14.35 ± 1.36 for sodium and Y = 0.980 X − 0.24 ± 0.21 for potassium.

Storage of blood for measurement of ph, PO2, PCO2

Abstract When samples of blood arc stored on ice (0 to 4°), there is no significant change in pH for the first 3 h. Similarly, measurements of PO2 and PCO2 arc not significantly changed after a storage period of 8 h.

Response of the pial circulation to fatty emboli studied by cinemicrophotography

Abstract 1.1. Cinemicrophotographic studies, through a port in the skull, were made of the response of the pial circulation in the monkey to emboli. 2.2. Dynamic effects upon vessels of from 200 to 20 micra were recorded. 3.3. Neither a generalized nor localized vasoconstriction was observed to occur in the vessels studied. 4.4. Arteries and veins expanded segmentally as globular and elongated fat particles traversed the vessels. This expansion permitted passage of an embolus much larger than the vessel involved. 5.5. Emboli appeared in the large veins (150 micra) seconds after their appearance in the arteries. Many were of large size (25 micra). Dilatation of the capillary bed or arteriovenous shunts may permit the passage of emboli from the arteries to the veins. 6.6. Through the application of this tool, perfected to permit higher magnification, more information concerning cerebral blood flow should become available.