Intracranial pressure in the normal monkey while awake and asleep

Area of Science:

• Neuroscience
• Physiology

Background:

• Intracranial pressure (ICP) regulation is crucial for brain health.
• Sleep stages are known to influence various physiological parameters.

Purpose of the Study:

• To investigate the characteristics of intracranial pressure (ICP) during different sleep stages in normal monkeys.
• To compare ICP variations during desynchronized sleep with known ICP phenomena.

Main Methods:

• Continuous ICP monitoring via telemetry in seven normal macaque monkeys.
• Simultaneous recording of electroencephalography, electromyography, and blood pressure.
• Analysis of ICP fluctuations across wakefulness and all sleep stages.

Main Results:

• During desynchronized sleep, mean ICP increased by 170 +/- 6 mm H2O.
• Pulsation pressure variation tripled during desynchronized sleep episodes.
• These episodes, occurring 10 +/- 2 times nightly, lasted 6.8 +/- 1.4 minutes with a concurrent 19 +/- 1.6 mm Hg drop in systemic blood pressure.
• Bilateral sympathectomy did not significantly affect these ICP waves.

Conclusions:

• Elevated ICP and increased pulsation pressure during desynchronized sleep are normal physiological characteristics in macaque monkeys.
• These findings resemble, but are of smaller magnitude than, Lundberg's plateau waves.
• The sympathetic nervous system does not appear to play a significant role in these sleep-related ICP changes.