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The effect of intracranial hypotension on cerebral blood flow in a feline model
S Pomeranz1, L Beni, M N Shalit
1Neurosurgery Department, Hadassah University Hospital, Jerusalem, Israel.
Insights
A novel feline model demonstrates that cerebrospinal fluid drainage can induce significant intracranial hypotension. This research indicates cerebral blood flow remains stable, suggesting symptoms are not due to reduced perfusion.
Area of Science:
- Neurology
- Neurosurgery
- Physiology
Background:
- Intracranial hypotension is a recognized condition, yet its underlying pathophysiology remains poorly understood.
- Cerebrospinal fluid (CSF) leakage or drainage is a known cause of intracranial hypotension.
Purpose of the Study:
- To develop and characterize a novel feline model for studying intracranial hypotension.
- To investigate cerebral blood flow and autoregulation during experimentally induced intracranial hypotension.
Main Methods:
- A kaolin-induced hydrocephalus model in cats was used, with controlled CSF drainage from a lateral ventricle.
- Intracranial pressure (ICP) was monitored, achieving levels of -15 to -80 torr.
- Regional cerebral blood flow in the cortex and subcortical nuclei was measured using the hydrogen clearance method.
Main Results:
- The feline model reliably produced significant intracranial hypotension, exceeding that achieved by cisterna magna drainage.
- Despite substantial intracranial hypotension (≥ -15 torr) and stable blood pressure, regional cerebral blood flow remained unchanged from baseline.
- Cerebral vascular autoregulation was maintained under conditions of significantly increased perfusion pressure due to negative ICP.
Conclusions:
- The developed feline model is effective for studying intracranial hypotension.
- Clinical symptoms associated with intracranial hypotension are likely not a result of decreased cerebral perfusion.
- Cerebral vascular autoregulation remains functional during experimentally induced intracranial hypotension.
Abstract:
Intracranial hypotension is a known clinical entity but its pathophysiology has been meagerly studied. Any setting with cerebrospinal fluid leakage or drainage can cause intracranial hypotension. A feline model of kaolin induced chronic hydrocephalus with controlled cerebrospinal fluid drainage from a lateral ventricle yields reproducible intracranial hypotension of up to -15 torr for several hours to -80 torr of about 10 minutes. The magnitude of this hypotension is significantly greater than can be attained by cisterna magna drainage. This new model allows multiple cerebral parameters to be studied during intracranial hypotension. In 11 cats with stable blood pressure and intracranial hypotension of at least -15 torr, regional blood flow utilizing the hydrogen clearance method in the cerebral cortex and subcortical nuclei was unchanged relative to the baseline. These results imply that: 1) cerebral vascular autoregulation is maintained during significantly increased perfusion pressure due to negative intracranial pressure, 2) the symptomatology of clinical intracranial hypotension is not due to decreased cerebral perfusion.
