The authors report the case of an ambulatory patient who presented with sleep apnea episodes of the central and obstructive types and an associated Chiari Type I malformation. The central episodes stopped and the obstructive episodes decreased markedly after decompression. The improvement in the so-called obstructive episodes was unexpected and indicates that they may have been on a central basis.

✓ Experiments were performed on 33 cats to determine the effects of subarachnoid blood on the electrical activity of the cerebral cortex. Electrocorticograms were obtained from both suprasylvian gyri by intracortical electrodes. Various preparations of autogenous whole blood were injected into the subarachnoid space overlying the suprasylvian gyrus of one side. These preparations included intact whole blood, hemolyzed whole blood, hemolyzed washed red blood cells with and without their membranes, and fresh serum. Lactated Ringer's solution and solutions high in potassium were also used. The preparations containing hemolyzed red blood cells produced much more pronounced effects than the other preparations, causing severe and prolonged suppression of activity in 11 of 15 cats, and spike activity in six. These phenomena did not appear in any other groups of cats in the study. Findings indicate that blood undergoing hemolysis in the subarachnoid space may have a direct effect on the electrical activity of the underlying cerebral cortex. This may in part explain the abnormalities seen in the electroencephalograms of patients with subarachnoid hemorrhage.

✓ A chronic canine model for the investigation of intracranial arterial spasm was designed and used to study spasm produced by rapid and slow cisternal injections of fresh or heparinized autogenous whole blood, or serum from incubated autogenous blood. Spasm so produced begins within 10 minutes after the injection and lasts from several hours to days. It affects primarily the major arteries of the circle of Willis, especially the proximal anterior cerebral arteries, and it does not seem to involve the extradural arterial tree.