Delayed intraparenchymal hemorrhage (DIPH), or delayed ipsilateral parenchymal hemorrhage, is a rare and serious complication following successful and otherwise uncomplicated endovascular treatment of intracranial aneurysms, usually with flow-diverter stents.
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Terminology
Although delayed ipsilateral parenchymal hemorrhage is the terminology often employed in the literature, there have been many reported cases of delayed parenchymal hemorrhage contralateral to the site of endovascular treatment 1. Thus, it may be more appropriate to utilize delayed intraparenchymal hemorrhage instead, as is used throughout this article.
Epidemiology
Delayed intraparenchymal hemorrhage 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 hemorrhage was noted in 2.2% of patients 3.
Associations
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saccular aneurysms: more common 2
possibly more common in giant cerebral saccular aneurysm 1
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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 hemorrhage 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 hemorrhage.
Pathology
The aetiopathogenesis of delayed intraparenchymal hemorrhage has not been fully elucidated. One theory suggests that endovascular therapy, in particular flow-diverter stenting, may alter the hemodynamics of the parent artery, leading to reduced arterial compliance and thus, higher systolic blood pressure peaks which can increase risk of hemorrhage 1,2. Other theories posit the role of antiplatelet therapy causing a bleeding diathesis, potential for hemorrhagic transformation of small intraoperative embolic ischemic 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 hemorrhage (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 hemorrhage 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 hemorrhage. Prognosis may be poor, with one large review suggesting a poor outcome in approximately 70% of patients with delayed intraparenchymal hemorrhage 1.
Differential diagnosis
other causes of spontaneous intracerebral hemorrhage