Since the introduction of pneumoencephalography by Dandy in 1918 (1) there have been few alterations in its technic. The introduction of fractional pneumoencephalography by Laruelle in 1933 (2) and its refinement by Robertson (3) did much to reduce the morbidity associated with the study. The documented reactions following air encephalography vary in severity and include headache, nausea and vomiting, perspiration, bradycardia, hypotension, and occasional syncopy (4–6). While various investigators (6–8) have used a variety of contrast gases for pneumoencephalography, filtered room air and oxygen are mainly employed (4–5, 7). The physical properties and high absorbability of carbon dioxide have been well established (9, 10). In this study these properties have been utilized in an attempt to determine whether CO2 could reduce the morbidity associated with pneumoencephalography. Material and Methods A total of 20 patients who have been studied by CO2 pneumoencephalography are the basis for this report. Routine fractional pneumoencephalographic positioning technics were employed. CO2 100 per cent was introduced from the cylinder,2 utilizing a reducing valve and air-flow meter, and was delivered through a Linde bacterial filter into a syringe. Cerebrospinal fluid samples were obtained prior to and after the introduction of CO2 to evaluate the pH and pCO2 levels. Serial films were taken after the introduction of CO2 to study the rate of absorption of the gas. In the first 15 patients CO2 was used as an initial probe to study the posterior fossa structures, and oxygen was then employed to delineate the remainder of the ventricular system. Complete pneumoencephalography has been obtained with CO2 alone in 5 patients. The following format was used. After the initial injection of 20 cc CO2, an autotomogram and a lateral and two frontal projections are obtained. An additional 50 cc CO2 is introduced with the patient in the erect position. He is then tilted into the brow-down position, and films of the occipital and posterior aspects of the lateral ventricles are obtained. The patient is returned to the erect position, and a further aliquot of CO2 is introduced, the quantity depending upon the amount of gas remaining in the ventricular system. The patient is immediately put in the brow-up position for views of the frontal horns and anterior part of the third ventricle. He is again returned to the erect position, and a further 30 cc of CO2 is introduced prior to the somersault maneuver to obtain views of the temporal horns. The total volume of gas used varies between 100 and 150 cc. Results Morbidity: The responses encountered during these studies appeared mild. In 3 patients CO2 induced slight headache, which cleared within ten minutes of the injection of a given aliquot of the gas.
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Apr 1, 1986
S A Sirr + 5
Open Access