Non Invasive Measurements of Intracranial Pressure After Aneurysmal Subarachnoid Hemorrhage

In patients at risk of increased intracranial pressure (ICP), ICP measurements require invasive transducers, usually with insertion of a catheter into the cranium, or through a spinal tap. These invasive modalities involve risks and pain and they can be done only in specialized care units, with a high associated cost.

A novel method for detecting changes in ICP has developed recently. The auditory hair cells emit sounds and electric signals in response to sound, which can be easily detected and measured non-invasively with the help of a microphone probe placed in the external ear canal or regular electrodes. Indeed, the cochlear aqueduct connects the cerebrospinal fluid (CSF) spaces to the inner ear in such a way that ICP and inner-ear fluid pressure equalize within seconds.

The evaluation of intracranial hypertension by increased ICP (invasive) is not systematically used after aneurysmal subarachnoid hemorrhage. It is then detected by using routine clinical signs of hydrocephalus or another disorder of cerebrospinal liquid flow, in combination with a standard imaging method (TDM).

The measurement of noninvasive ICP could allow earlier detection of hydrocephalus or another disorder of cerebrospinal liquid flow, and evaluate whether the increase in ICP precedes patient clinical worsening and / or imaging.

In patients at risk of increased intracranial pressure (ICP), ICP measurements require invasive transducers, usually with insertion of a catheter into the cranium, or through a spinal tap. These invasive modalities involve risks and pain and they can be done only in specialized care units, with a high associated cost.

A novel method for detecting changes in ICP has developed recently. The auditory hair cells emit sounds and electric signals in response to sound, which can be easily detected and measured non-invasively with the help of a microphone probe placed in the external ear canal or regular electrodes. Indeed, the cochlear aqueduct connects the cerebrospinal fluid (CSF) spaces to the inner ear in such a way that ICP and inner-ear fluid pressure equalize within seconds.

The evaluation of intracranial hypertension by increased ICP (invasive) is not systematically used after aneurysmal subarachnoid hemorrhage. It is then detected by using routine clinical signs of hydrocephalus or another disorder of cerebrospinal liquid flow, in combination with a standard imaging method (TDM).

The measurement of noninvasive ICP could allow earlier detection of hydrocephalus or another disorder of cerebrospinal liquid flow, and evaluate whether the increase in ICP precedes patient clinical worsening and / or imaging.

Eligibility Criteria:
Inclusion Criteria:

* Patients which had recently (few days) aneurysmal subarachnoid hemorrhage
* Valid tympanometry test at least for one ear
* Between 18 and 75 years of age
* Cochlear response useful at least for an ear which has validate the tympanometry test
* Written informed consent reviewed and signed by patient
* Affiliation to a social security scheme

Exclusion Criteria:

* Invalid tympanometry test for the both ears
* Collect of cochlear responses impossible for the ear or both ear which validate the tympanometry test
* Patient refusal after enlightened information