Chemical mediators of the vascular phenomena of the acute inflammatory reaction and of immediate hypersensitivity

Nonsurgical management of extradural hematomas in children

With the advent of computerized tomography (CT), an increasing number of patients with only minimal neurological symptoms and no signs of brain herniation are found to harbor subacute or chronic extradural hematomas (EH's). The authors present the cases of 11 symptomatic but neurologically normal children with medium to large EH's managed by close observation. These EH's were discovered 4 hours to 6 days after injury; three were in the posterior fossa, seven over the frontoparietal convexity, and one in the temporal fossa. These clots were followed by serial CT scans. Nine children recovered without surgery from 4 to 18 days after injury, and all had evidence on CT of spontaneous clot resorption. Of these nine EH's, five clots displayed volume expansion from 5 to 16 days after injury before final resorption occurred. Expansion correlated with persistence or increase in symptoms, whereas resorption correlated with improvement. Two patients showed gradual uncal herniation on Days 6 and 8, respectively, presumably during the "expansile phase" of their clots. Both had emergency craniotomy and recovered without morbidity. It is hypothesized that the resorption dynamics of the subacute or chronic EH are similar to that of the chronic subdural hematoma, with predictable volume changes, and the outcome of each lesion depends on the interplay between the patient's intracranial pressure buffering capacity and the rate of volume change. If subtle signs of brain dysfunction are adopted to signal the failure of conservative treatment and the need for craniotomy, these patients may be safely, and many successfully, managed without surgery. Factors that influence outcome of medical treatment include the size, location, configuration, and the rapidity of accumulation of the clot, the presence of associated intradural lesions, the extracranial decompression of blood through skull diastases, and the age of the patient. These factors, the criteria for patient selection, and the indications for immediate operative intervention are discussed.

Physiopathogenesis of subdural hematomas. Part 2: Inhibition of growth of experimental hematomas with dexamethasone

A previously described experimental hematoma model, achieved by the subcutaneous injection of 12 ml of autologous hemolyzed blood clotted in situ, was made in 33 rats. Sventeen animals served as controls; the other 16 received daily intra-muscular injections of dexamethasone. After an initial decrease in size, 47% of the lesions in the control animals enlarged to a mean weight of 12.1 +/- 2.5 gm, while the lesions in the 16 steroid-treated rats weighted 3.2 +/- 0.70 gm (p less than 0.01). Histologically, lesions from the steroid group showed absence of neomembrane formation. These data offer further support to the theory that the neomembrane development and subsequent enlargement of subdural hematomas is due to inflammatory reactions of tissues in contact with large blood clots.

Physiopathogenesis of subdural hematomas. Part 1: Histological and biochemical comparisons of subcutaneous hematoma in rats with subdural hematoma in man

The dorsal subcutaneous injection in rats of 12 ml or more of autologous hemolyzed whole blood clotted in situ induced the formation of sterile, hemispheric lesions, 47% of which showed an initial decrease in volume followed by a progressive enlargement. The behavior, histology, and biochemical characteristics of the liquid contents of these lesions were found to be remarkably similar to those of subdural hematomas in man. To evaluate the role of the various blood components that may have influenced the formation and growth of these lesions, more than 150 clots composed of human platelet-free plasma, autologous hemolyzed blood, or autologous whole blood were implanted subcutaneously in rats by either surgical or injection techniques. The in vitro behavior of the different clots used was also assessed. This systematic approach led to the following conclusions: 1) the composition and volumes of the clots are critical variables; 2) plasma-fibrin provides the matrix shape of the lesions; 3) the breakdown products derived from erythrocytes, hemoglobin, leukocytes, and other solid blood elements induce neomembrane formation and contribute to the lesion's subsequent growth; and 4) inflammation mechanisms appear to be essential, while cerebrospinal fluid plays no discernable role in this process.