Subarachnoid haemorrhage (SAH) secondary to ruptured aneurysm represents 5 to 15% of all cases of stroke. The mortality rate of SAH is 40% and the risk of serious neurological sequelae among survivors is 10 to 20%.The causes of morbidity and mortality are mainly related to the initial damage induced by SAH and delayed cerebral ischaemia (DCI), which is generally secondary to cerebral vasospasm.

Cerebral vasospasm is one of the main factors of poor prognosis after SAH, as it is associated with a 1.5- to 3-fold increase in the mortality rate during the 2 weeks following SAH in these patients.

Despite a significant improvement in the time to management of this disease and the fact that the ruptured aneurysm is very often rapidly excluded by surgical or endovascular intervention, patients who survive the initial SAH remain at risk of severe complications over the following 2 weeks.

Vascular stenosis of an arterial segment, called cerebral vasospasm, is observed in more than 70 to 95% of cases on digital subtraction angiography between the 7th and 14th days after ruptured aneurysm. This angiographic vasospasm can be responsible for cerebral infarction in 52 to 81% of cases.

Despite 50 years of research, no clearly demonstrated effective treatment for vasospasm is currently available.

This is a multicentre, randomized, comparative study, including 364 patients during the acute phase following ruptured aneurysm, in whom management is very often limited to control of complications, after exclusion of the aneurysm.

The objective of this study is to validate the efficacy of transcutaneous trigeminal nerve stimulation for the prevention of vasospasm and limitation of the consequences of delayed cerebral ischaemia after SAH.

This is an innovative project, as it comprises intervention in these patients prior to the development of complications and could limit the development of these complications. The prevention tool, based on external facial nerve stimulation, is a totally innovative, reversible and noninvasive technique. Use of nerve stimulation in this indication has never been previously reported and could radically modify the intensive care management of this disease over the years to come.

Inclusion Criteria:

• Age ≥ 18 years and ≤ 75 years.
• Admission within 48 h after onset of SAH.
• Ruptured cerebral aneurysm confirmed on CT angiography or cerebral angiography.
• Patient classified as grade I-IV according to the WFNS (World Federation of Neurological Surgeons) classification.
• Covered by French national health insurance.
• Absence of active cancer.

Exclusion Criteria:

• Age < 18 years and > 75 years.
• Absence of signature of the informed consent form by the patient or a close relative.
• Person subject to reinforced protection Clinical state on admission classified as WFNS grade V (excessively high mortality rate).
• Intracerebral or intraventricular haemorrhage without subarachnoid involvement.
• Major complication during the aneurysm exclusion procedure.
• SAH with no demonstrated aneurysm.
• Presence of non-ruptured cerebral aneurysm.
• Contraindication to placement of a transcutaneous device.