Guidance assessment consultation for HTG10869 Middle meningeal artery embolisation for non-acute subdural haematomas

A subdural haematoma is an accumulation of blood and blood degradation products in the space between the brain and one of its surrounding membranes (the dura). This space is referred to as the subdural space. A subdural haematoma is usually caused by a head injury. But, with non-acute subdural haematomas, the cause is often a minor head injury. Symptoms usually develop more slowly compared with acute haematomas, and the blood has typically been present for weeks or months. During this time, there will also have been some changes in normal biological processes such as the formation of an inflammatory membrane.

Non-acute subdural haematomas can present with a variety of symptoms. These range from mild headaches to motor and cognition problems, and reduced consciousness. Some people may not have any symptoms at all.

Non-acute subdural haematomas with symptoms, or with minor or no symptoms but radiological evidence of a large volume haematoma with mass effect, are usually treated with surgery. The haematoma can be surgically drained through a burr hole (burr-hole evacuation) or a craniotomy.

Haematomas are usually managed with conservative treatment if they are:

• associated with minor or no symptoms

• small in size

• any size and the risk of surgery is too high.
  
  This involves careful monitoring and medical management such as temporarily stopping or reversing treatment with anticoagulants or antiplatelets.

It is common for a non-acute subdural haematoma to recur after surgical removal. When this happens, reoperation or surgical rescue is often needed. These further interventions can lead to complications such as stroke, myocardial infarction or death. Some people may be unable to start or restart anticoagulants or antiplatelets after surgery to remove the haematoma because of the risk of recurrence. MMAE could reduce the rate of recurrence and lead to better outcomes for people with non-acute subdural haematomas.

Conservative management of non-acute subdural haematomas when surgery is too high a risk or not clinically indicated can be associated with high morbidity and mortality rates. MMAE could provide another option and lead to better outcomes for these people.

MMAE is a minimally invasive procedure because the skull does not need to be opened to do it. In contrast with surgical procedures which drain the haematoma, MMAE targets the underlying source of bleeding.

The evidence included 11 randomised controlled trials and 6 systematic reviews. Six different devices were used in the studies informing this guidance, including both particle and liquid embolic agents. The evidence is presented in the interventional procedures external assessment report. Other relevant literature is in the appendices of the external assessment report.

The professional experts, patient experts and the committee considered the key efficacy outcomes to be:

• symptomatic recurrence

• need for further intervention

• functional outcomes including cognitive function

• change in neurological symptoms including headaches

• quality of life.

The professional experts, patient experts and the committee considered the key safety outcomes to be:

• mortality

• stroke or myocardial infarction

• neurological complications including visual loss

• procedure or device-related adverse events or complications.

Six commentaries from people who have had this procedure were discussed by the committee.

The procedure may particularly benefit people with non-acute subdural haematomas that have recurred or that have a high likelihood of recurring. This is because it could prevent the need for additional surgical procedures.

There were differences in the eligibility criteria, severity of neurological disability, and suitability or clinical need for surgery in the populations in the included studies. More evidence is needed on patient selection and who would benefit most from MMAE.

Outcomes related to quality of life, cognitive and functional improvement, and headaches are important efficacy outcomes for people with non-acute subdural haematomas.

The committee acknowledged that there are ongoing trials and that they may also provide relevant evidence.

The risk of non-acute subdural haematomas increases with age. Older age is also associated with increased risk of falls, and with use of anticoagulants or antiplatelets.

Some people are unable to have surgery because of older age, frailty or other contraindications. These people may be thought to have a disability if their condition is likely to have or has had a substantial adverse impact on normal day-today activities for more than 12 months.

There are regional disparities in access to neurosurgery centres.