Lyle A. French

Lateralized deficits in complex visual discrimination and bilateral transfer of reminiscence following unilateral temporal lobectomy

Abstract Differential deficits in complex visual discrimination and bilateral reminiscence in symbolic learning were assessed after left as compared with right temporal lobectomy in man. A deficit in the ability to discriminate between fragmented concentric circle patterns was found in the right temporal lobectomy group. The left temporal group exhibited a selectively lower left to right hand performance increment in inverted alphabet printing with interpolated rest. Stimulus complexity was inferred to be more effective than the level of visuospatial integration required by the task for eliciting deficits in visually guided behavior after right temporal lobectomy. Differences between the groups in the rate of interhemispheric dissipation of inhibitory effects in symbolic learning was postulated to account for the lower magnitude of bilateral reminiscence observed after left temporal lobectomy.

The Clinical Effects of a Synthetic Gluco-Corticoid used for Brain Edema in the Practice of Neurosurgery

The clinical effect of dexamethasone, a potent, synthetic gluco-corticoid, was studied in a large series of neurosurgical patients with brain edema seen over a 12 year period. A protocol was established at the beginning of the study to evaluate the severity of the edema and its clinical response to steroid therapy. The results showed that the treatment of brain edema with dexamethasone was highly effective in patients with focal lesions where edema production persists or progresses with time, as is the case particularly with brain tumors and abscesses. Patients with metastatic tumors, glioblastomas and abscesses responded better to steroid therapy than patients with low grade infiltrating astrocytomas and meningiomas. This correlated well with the relative severity of the edema associated with these respective tumors. Steroid administration proved least effective in patients with generalized brain lesions of acute onset as seen in severe closed head injuries. The prevention of severe operative and post-operative edema in patients started on dexamethasone prior to brain surgery was apparent. This was particularly emphasized in the group of patients who had craniotomies for the excision of large meningiomas and the pathophysiology of this response was discussed. Steroid therapy proved to be safe when administered for the brief period of time usually necessary in neurosurgical problems. Gastrointestinal bleeding was not a serious problem except in very ill patients who were either comatose and on the respirator, or moribund following severe head injuries with brain stem involvement.

The effects of glucosteroids upon cold induced brain edema. II. Ultrastructural evaluation.

The acute brain edema which follows a cortical cold lesion is characterized by the appearance of fibril-filled astrocytes within hours of lesion production. This gliosis is steadily progressive for many months after injury. Prompt alleviation of the edema with glucosteroids greatly reduces the severity of the process.

Multiple Therapeutic Approaches in the Treatment of Brain Edema Induced by a Standard Cold Lesion

Brain edema was produced by a standard cortical freezing lesion. The temporal course of the evolution and resolution of this edema has been reported elsewhere in detail. The effects of many types of therapy, both standard and investigational, upon this model of brain edema have been employed. Osmotic diuretics were found to have no effect upon the edema itself, but a reduction in the bulk of normal brain was evident. Maintenance of hypotension after lesion production essentially eliminated brain edema whereas prolonged hypertension increased brain edema dramatically. Focal excision of the cold injury itself immediately after lesion production prevented the development of brain edema. A beneficial effect on brain edema by focal excision was evident up to 24 h after injury at all time points from 6 h on. The addition of glucosteroids to focal excision reduced edema even further. Treatment of animals with dibenzyline, dimethyl sulfoxide, and diphenyl-p-phenylenediamine also had a beneficial effect upon the development of edema. Combination of steroids and osmotic diuretics was not of value. Focal excision with acetazolamide was extremely effective in reducing brain edema. A combination of DMSO and dexamethasone was more effective than either drug alone. Detailed studies to elucidate the effects of hypotension or hypertension in each of these therapeutic regimens were carried out.

The Effects of Glucosteroids upon Experimental Brain Edema

Brain edema has been produced in rabbits, cats, dogs, and monkeys by the intracranial implantation of hydrophillic materials, stab wounds, implantation of viable brain tumors, inflation of extradural or subdural balloons, and cortical or spinal cord freezing injury. The temporal course of the evolution and resolution of brain edema in each of these models has been studied by gross photography, the extravasation of fluorescent protein tracers, wet weight/dry weight determinations, light microscopy, histochemistry, and electron microscopy. In a similar series of animals, the effects of glucosteroids given in several ways have been evaluated. Dexamethasone, cortisone, prednisone, and prednisolone have been utilized in dosages varying from 0.25 to 2.5 mg/kg/24 h. Animals have been pre-treated with steroids for 24 and 48 h prior to lesion production, and steroids have then been begun at the time of lesion production and at regular intervals up to 72 h after lesion production. The effects of the administration of glucosteroids upon the same parameters of edema estimation have been assessed. The cold injury model provides the best quantitative data. The administration of glucosteroids to animals in which a cold or spinal cord freezing injury has been inflicted results in a gross reduction in brain edema with reduced extravasation of dye protein complexes. Wet weight/dry weight determinations demonstrate significant retardations in the development of brain edema. At 24 and 48 h there is an approximate 50% reduction in edema, and at 72 h, a reduction of almost 30% persists. Light microscopic and histochemical differences were not striking. Electron microscopic studies revealed definite reduction in astrocytic volume and in white matter extracellular space in treated animals. The resolution of edema appeared to be accelerated. In addition, there was a marked reduction in postedema astrogliosis in animals receiving glucosteroids.

Systemic absorption and urinary excretion of RISA from subarachnoid space.

THIS IS a preliminary report of a study on systemic absorption and clearance of radioactive iodinated human serum albumin ( RISA) injected intrathecally in the lumbar region. It is also an investigation of the rate of diffusion of RISA in the cerebrospinal fluid along the neural axis. When RISA is injected intravenously, its diffusion into various fluid compartments of the body including the cerebrospinal fluid, its metabolic turnover, and its biologic half-life have been documented.’#* Furthermore, various substances, radioactive or otherwise, have also been studied with respect to the rate of diffusion into cerebrospinal fluid from the systemic circulation. However, there have been few reports on the “reverse traffic” of substances from the cerebrospinal fluid to the blood stream. It is hoped to find an optimum interval for performing isotope ventriculography with scanning scintillation apparatus by learning the diffusion rate of RISA in the cerebrospinal fluid and absorption and clearance rates from the blood. METHOD

Increased intracranial pressure following compression of the superior sagittal sinus.

THIS report presents a case in which evidence of increased intracranial pressure developed slowly following compression of the superior longitudinal sinus in the posterior parietal area by a depressed bone fragment. Dural sinus pressure recordings and venograms before and after elevation of the fragment were performed by Rays method.1 The evidence of increased intracranial pressure resolved following removal of the compression. Wharton? in 1901 published a detailed report on traumatic involvement of the dural sinuses in which he collected 65 cases from the literature and reported on five of his own. He recognized certain dangers associated with elevation of the bone fragments, such as profuse hemorrhage, thrombosis and air embolism. He did not stress the syndrome resulting from compression of the sinus. I t was not until 1915 when Holmes and Sargents reported 78 cases of traumatic obstruction of the superior longitudinal sinus that the syndrome resulting from occlusion of the superior longitudinal sinus at or posterior to the Rolandic veins was emphasized. In their reported cases the syndrome varied in severity from involvement of one leg to a spastic quadriplegia. At least one arm was affected in 57 of the 78 cases, but never were the face or speech affected. When the lesion was located more posteriorly, a marked disturbance was observed in stereognosis, position sense, and twopoint discrimination. Also retention of urine was common, focal seizures occurred in 15 per cent of patients, and papilledema was observed frequently. Subsequently others have reported on the symptomatology and complications of dural sinus injury.4-lo

Ultrastructural Substrates of Experimental Cerebral Edema

The developing clinical interest in cerebral edema and its neuropathological definition has been paralled by an increasing number of attempts to produce an adequate experimental model for the study of this process. The entity has been vigorously studied and there is a voluminous literature on the subject filled with conflicting reports and divergent opinions with regard to both reliability of methods and morphological changes produced.

ACUTE EFFECT OF SECTION OF THE CORPUS CALLOSUM UPON “INDEPENDENT” EPILEPTIFORM ACTIVITY

A nine year old boy presented a right hemiparesis and convulsive seizures since infancy. Convulsions could not be controlled in spite of large doses of anticonvulsant drugs. The child was severely mentally retarded. A pneumoencephalogram revealed a large porencephalic cyst and generalized atrophy of the left hemisphere. Electroencephalography showed multiple spike foci discharging independently on both hemispheres. Scalp electrodes were applied to the right side before exposing surgically the left hemisphere. Simultaneous recording was performed from right scalp and left cortical electrodes. Active spikes were recorded independently from both sides. After section of the corpus cal‐losum, the spikes from the right disappeared; the left side showed no changes. Left hemispherectomy was then performed. The implications of these results are discussed in the context of criteria for definition of independent spikes in the EEG and of the existence of mirror foci in man.

Readaptation to prismatic rotations of visual space as a function of lesion laterality and extratemporal EEG spike activity after temporal lobectomy

Abstract An attempt was made to analyze lateral differences in visuospatial functioning after unilateral temporal lobectomy by quantifying the contact and travel components of a visoumotor readaptation to rotated visual space. Although no differences emerged as a function of lesion laterality, the presence of extratemporal EEG spike foci was associated with an elongated contact component under most conditions other than the more difficult positions utilized. Selectively longer contact durations were present at these difficult rotations in patients with extratemporal EEG spike activity after right as compared with left temporal lobectomy. The results were discussed in terms of current theories of cerebral function in man.