Delayed intraparenchymal haemorrhage

Delayed intraparenchymal haemorrhage (DIPH), or delayed ipsilateral parenchymal haemorrhage, is a rare and serious complication following successful and otherwise uncomplicated endovascular treatment of intracranial aneurysms, usually with flow-diverter stents.

Terminology

Although delayed ipsilateral parenchymal haemorrhage is the terminology often employed in the literature, there have been many reported cases of delayed parenchymal haemorrhage contralateral to the site of endovascular treatment ¹. Thus, it may be more appropriate to utilise delayed intraparenchymal haemorrhage instead, as is used throughout this article.

Epidemiology

Delayed intraparenchymal haemorrhage is rare, reported in one series to occur in 8.5% of patients with intracranial anterior circulation aneurysms treated with flow-diverter stents ². In another series of patients with intracranial saccular aneurysms managed with stent-assisted coiling, delayed intraparenchymal haemorrhage was noted in 2.2% of patients ³.

Associations

• saccular aneurysms: more common ²

  • possibly more common in giant cerebral saccular aneurysm ¹

• anterior circulation aneurysm location: more common ¹

  • particularly common in internal carotid artery aneurysms ¹

• use of flow-diverter stent as endovascular therapy: more common ^1,2

Clinical presentation

Delayed intraparenchymal haemorrhage usually (~80%) occurs within 30 days, with most cases (~60%) occurring within 7 days, of otherwise uncomplicated endovascular aneurysmal treatment ^1-3. The clinical presentation may be incredibly varied depending on the location and size of the intracerebral haemorrhage.

Pathology

The aetiopathogenesis of delayed intraparenchymal haemorrhage has not been fully elucidated. One theory suggests that endovascular therapy, in particular flow-diverter stenting, may alter the haemodynamics of the parent artery, leading to reduced arterial compliance and thus, higher systolic blood pressure peaks which can increase risk of haemorrhage ^1,2. Other theories posit the role of antiplatelet therapy causing a bleeding diathesis, potential for haemorrhagic transformation of small intraoperative embolic ischaemic strokes, the role of intraoperative foreign body emboli (e.g. polyvinylpyrrolidone) from endovascular catheters or devices, or the role of flow reversal in distal collaterals ^1-6.

Radiographic features

CT/MRI

Radiographic features are those of intracerebral haemorrhage (please see that article for a detailed discussion regarding general radiographic features), anatomically remote to the location of the aneurysm and endovascular therapy ^1-5. In most cases (~80%), the delayed intraparenchymal haemorrhage is ipsilateral to and in the same vascular territory of the site of endovascular therapy ¹. 

Treatment and prognosis

Management does not differ from other causes of intracerebral haemorrhage. Prognosis may be poor, with one large review suggesting a poor outcome in approximately 70% of patients with delayed intraparenchymal haemorrhage ¹. 

Differential diagnosis

• other causes of spontaneous intracerebral haemorrhage

• delayed aneurysm rupture