The aim of this study is to assess the diagnostic ability of quantitative pupillometry for the early detection of hydrocephalus during the weaning process of the external ventricular drain.

Acute hydrocephalus is an emergency often requiring the insertion of an external ventricular drain (EVD). In the aftermath, the patient is transferred to an intensive care unit (ICU) for close monitoring. Ensuring optimal cerebral perfusion through efficient drainage of cerebrospinal fluid while minimizing drainage duration are the objectives of care.

Assessing pupillary light reflex is a key test for the detection of neurological deterioration. For long, this assessment has been grossly performed via a qualitative approach (present/absence of pupillary light reflex). For a more precise assessment, quantitative pupillometry has been proposed. Pupil size and constriction speed in response to a standard light are recorded by an automatic portable and user-friendly device. This device is increasingly used in the ICU, mostly for prognostication after acute brain injury. We hypothesized that quantitative pupillometry parameters may vary when hydrocephalus occurs.

The aim of this study is to assess whether quantitative pupillometry parameters vary when hydrocephalus occurs. The investigators focused on the early detection of hydrocephalus during the EVD weaning process.

Inclusion Criteria :

• Patient older than 18 years old
• Admitted to the ICU
• With an external ventricular drain
• Consenting to participate (or consent from his/her next of kin, if unable to consent).

Exclusion Criteria :

• Patient with pre-existing bilateral pupillary pathology
• Pregnant or breast-feeding patient
• Moribund patient or patient with decision of withholding or withdrawing life-sustaining treatment
• Patient with no health insurance
• Patient under guardianship

Adult ICU patients with an EVD included at the beginning of the weaning process