Ventriculography and Myelography with Absorbable Radiopaque Medium

Abstract

Positive contrast radiographic studies of the central nervous system were first reported by Sicard and Forestier in 1922, using Lipiodol (8). Other substances investigated since that time include Abrodil (1), Thorotrast (5), Perabrodil or Diodrast (2), Pantopaque (4, 6, 9, 10, 11), Hypaque (3), and various chelate compounds (7). Failures with air, Pantopaque, and Lipiodol at stereotaxic surgery and in suspected midline tumors aroused our interest in absorbable positive contrast media. This paper reviews our investigations with Conray and other water-soluble positive contrast agents. Laboratory Investigations LD50 Study: A previous report indicated that Conray was less toxic than other similar compounds when injected cisternally in the rabbit. Toxicity studies were carried out in our laboratory with Conray, Hypaque, Skiodan, and a series of experimental compounds. These will be reported in detail later, but Conray was found to be considerably less toxic than either Hypaque or Skiodan. Isotope Studies: l131-tagged sodium iothalamate, mixed with the methylglucamine salt in a ratio of 1: 4, was injected cisternally in 6 dogs. The concentration in the blood reached a plateau at forty-five to seventy-five minutes and then decreased in an exponential fashion. Nearly 100 per cent of the radioactivity could be recovered in the urine within twenty-four hours. Radioautographs indicated that the compound entered the brain and spinal cord in a centripetal manner. Radiographic Study: Serial radiography was performed in 4 dogs at ten-minute intervals following cisternal injection of Conray. The urinary bladder was opacified ten minutes after injection. Con ray was usually no longer radiographically visible in the subarachnoid space thirty minutes after injection. The ventricles were never visualized. Electroencephalography: Electroencephalographic recordings were obtained following cisternal injection of Conray. Focal cortical seizure activity from the dependent hemisphere appeared within ten minutes when the dog was kept in the lateral position. Seizures occurred regularly with a dosage of 200 mg./kg. or more. Electrocorticography: Electrocorticography has been performed in dogs with Conray and other agents. Spike activity developed, even with isotonic concentrations of Conray and other compounds, following their subarachnoid injection over the cortex with a No. 30 gauge needle. Histologic Studies: A series of dogs was studied to determine alteration of enzyme activity. Lipid, myelin sheath, and axis cylinder staining were also performed. These studies failed to demonstrate any changes from the control group. Histologic examination of 2 patients who died shortly after a Conray injection failed to show any changes attributable to Conray. Clinical Material Ventriculography: The first Conray ventriculography in man was performed by one of us (R. F. H.) on April 4, 1962.