A life-saving technique dubbed a "brain bypass" has been carried out for the first time in the UK.
The op has only previously been performed abroad
The operation, which has been carried out abroad, was performed on four UK patients with brain tumours and aneurysms - blood vessel weakness.
It works - like a heart bypass - by re-routing blood supply around the problem using a piece of grafted vein.
All the operations were carried out successfully, the London King's College Hospital team said.
The technique, known as Elana, was originally developed in Holland and has been carried out on about 300 patients worldwide so far.
The main benefit is that it eliminates the need to temporarily clip the artery and cut off the blood supply, which increases the risk of stroke.
Neurosurgeon Christos Tolias, who headed the team, said the operations were a "real advancement in the field".
"In all operations performed no patient has died or suffered deterioration as a result of using this technique, as compared to conventional treatment.
"The advancement will make a significant difference to the treatment we can offer these patients.
"The traditional method will still be used for the majority of cases, but this gives us an option for people with large tumours or aneurysms where clipping is not sufficient."
The technique has been used on a patient with a tumour at the base of the skull and three with giant aneurysms.
It uses two specially designed tools, a laser catheter and an implanted ring.
The catheter makes a hole in the affected vessel wall, and the ring prepares the connection between the artery and the graft vein.
The ring is either directly attached to the artery, with the graft vein being attached afterwards or the graft and the ring can be attached simultaneously. This is done using microsurgical techniques.
The laser catheter is then inserted into the graft vein, and cuts out a hole through the artery wall.
Blood flow through the graft indicates that penetration of the artery has been successful.
The tumour or aneurysm can then be cut away or isolated.
But Professor Tipu Aziz, a neurosurgeon at Oxford's John Radcliffe Hosptial, said the technique was not new.
"As well as being used in other countries, the approach is used in other bypass operations.
"I would also say that this form of survery will only be relevant to a select few patients."