Cerebral spinal fluid pressure: effects of body position and lumbar subarachnoid drainage in a canine model.
STUDY DESIGN: This study used in vivo an model of subarachnoid cerebrospinal fluid pressure measurement. OBJECTIVES: To examine the relation between subarachnoid cerebrospinal fluid pressure in the cervical and lumbar spine and varying body positions, and to test the hypothesis that increasing body inclination and lumbar subarachnoid drainage decreases cervical cerebrospinal fluid pressures. SUMMARY OF BACKGROUND DATA: Cerebrospinal fluid leaks are a recognized complication of anterior or posterior cervical surgery. Conflicting opinion exists regarding the benefits of postoperative patient positioning and lumbar subarachnoid drainage. METHODS: Subarachnoid cerebrospinal fluid pressure of 7 beagles was monitored via two angiocatheters attached to pressure transducers inserted into the subarachnoid space through laminectomies at C3 and L4. Pressure measurements were taken when body position was inclined to 30 degrees, 60 degrees, and 90 degrees. A lumbar durotomy was performed to simulate the effects of lumbar subarachnoid drainage. The body was repositioned to 90 degrees, and pressure was measured. RESULTS: As inclination increased from 0 degrees to 90 degrees, the mean cervical cerebrospinal fluid pressure significantly decreased. The mean lumbar subarachnoid pressure significantly increased as inclination increased from 0 degrees to 90 degrees. Lumbar durotomy plus repositioning to 90 degrees resulted in a significant reduction in cervical cerebrospinal fluid subarachnoid pressure, with pressures dropping by 46%. Lumbar cerebrospinal fluid subarachnoid pressure dropped to zero after lumbar durotomy plus repositioning to 90 degrees. CONCLUSIONS: Cerebrospinal fluid pressures in the subarachnoid space of both the cervical and lumbar spines are affected by changes in body position. Both patient positioning and lumbar drainage may be important in reducing cervical cerebrospinal fluid pressure, and may reduce the occurrence of cerebrospinal fluid leaks after primary dural repair in the neck.