Operations on the central nervous system are frequently accompanied by a marked diminution in the blood pressure. This decline in pressure, however, is not of as grave concern as a like drop in blood pressure during an abdominal operation. The pressure may reach a low level during an operation on the central nervous system, but if the operative procedure is stopped immediately, the pressure will usually rise without any artificial aid. In a report from the surgical clinic of Dr. Harvey Cushing, Bird1 stated, "During operations for intracranial tumors, patients have been observed who, though their blood pressure remained too low to be recorded for from thirty minutes to three hours, recovered after spontaneously 'picking up' or following transfusion, without detectable injury to nervous tissue or other permanent ill effect." Most of these patients had lost a moderate amount of blood.
The use of the word "shock" is intentionally