Neurophysiology: Age-related changes
This chapter outlines fundamental concepts of cerebral physiology with special reference to variations and alterations in the geriatric population. Skull is a non-expandable rigid semi-closed compartment housing three intracranial components: brain parenchyma (including interstitial fluid), blood, and cerebrospinal fluid (CSF). CSF formation exists in dynamic equilibrium, with continuous absorption taking place through specialized structures called arachnoid villi and granulations. The aging brain and cranium are known to undergo structural changes that can alter craniocerebral responses to both physiological and pharmacological stimuli. Intracranial pressure (ICP) is a direct determinant of the cerebral perfusion pressure and cerebral blood flow, making its monitoring vital for the assessment and management of various clinical neurosurgical and neurological conditions. Clinically, ICP is monitored mostly by invasive methods. The methods can be classified based on the location of placement of the catheter or pressure transducer into intraventricular, subdural/epidural, and intraparenchymal.