Lobar intracerebral haemorrhage

Lobar intracerebral haemorrhage is a subtype of intracerebral haemorrhage defined by their location in the peripheral cerebral hemispheres. Compared to deep intracerebral haemorrhages (involving the deep grey nuclei or brainstem), lobar haemorrhages are less likely to be related to hypertension and more likely to be due to cerebral amyloid angiopathy or trauma. This article concerns spontaneous (non-traumatic) lobar intracerebral haemorrhages.

Epidemiology

Primary lobar haemorrhage accounts for approximately 3.9% of acute strokes and 35% of intracerebral haemorrhages ¹.

Cerebral amyloid angiopathy is a major risk factor for lobar haemorrhage, with estimates that over 20% of lobar haemorrhages were due to cerebral amyloid angiopathy (majority of which are seen in elderly patients). Hypertension, diabetes, smoking, short stature, dyslipidaemia, and anticoagulant use are also significantly associated with primary intracerebral haemorrhage.

Younger patients may also develop lobar haemorrhages, but in such cases there is usually an underlying lesion (e.g. cerebral arteriovenous malformation) ^2,8.

Clinical presentation

Clinical presentation will vary depending on the site and size of the haemorrhage. Potential clinical features include ¹⁶:

• headache and vomiting are the most common symptoms at initial presentation

• focal neurological deficits

• seizure can also occur during the onset of the lobar haemorrhage (focal or generalised with a brief duration)

• delirium is increasingly being recognised as a common finding and can be the initial presenting illness

• decreased conscious state

Pathology

Aetiology

Often the cause of a lobar haemorrhage is never established and the causes, when found, are varied including ^9,10:

• cerebral amyloid angiopathy

• hypertension

  • primary

  • secondary to drug use (e.g. cocaine, amphetamines)

• cerebral aneurysm: both saccular and mycotic

• arteriovenous malformation

• cerebral cavernoma

• brain tumour

  • glioma

  • brain metastasis

• bleeding disorders or coagulopathies

• anticoagulation - therapeutic or supratherapeutic levels

• vasculitis

• cerebral venous thrombosis

One of the strongest predictors of an underlying vascular lesion is the patient's age ¹¹. The younger a patient, the more likely there is an identifiable cause: CT angiography found causes for haemorrhage in 47% of patients aged 18-45 years, 15% aged 46-70 years, and 4% aged 71-94 ¹¹.

Radiographic features

Overall features of the haemorrhage that suggest an underlying secondary cause are ¹²:

• internal density heterogeneity

• highly irregular margin

• fluid-fluid level

• internal haematocrit level

• extensive surrounding vasogenic oedema

• extensive subarachnoid haemorrhage

CT

CT is usually the modality first obtained when evaluating a suspected lobar haemorrhage. Noncontrast enhanced CT typically demonstrates a hyperdense collection of blood, located superficially within the lobes of the brain (i.e. not in the basal ganglia).

The haemorrhages can vary in size from only a centimetre or so (often asymptomatic) to larger haematomas where there may be extension into subdural, subarachnoid and even the intraventricular space (intraventricular extension being more common in basal ganglia haemorrhages). The ABC/2 formula gives reliable estimation of the intracerebral haematoma volume.

There are many predictors of haematoma expansion potentially evident on CT, which are discussed in depth in the main intracerebral haemorrhage article.

CT angiography

CTA is increasingly being used in the initial workup, not only to assess for an underlying abnormality such as arteriovenous malformations, vasospasm, and aneurysmal disease, but also to evaluate for the presence of ongoing bleed.

The CTA spot sign, characterised by a defined "spot" or foci, is a radiographic sign indicative of ongoing bleeding. The presence of the spot sign correlates with growth of the haemorrhage in the first few hours following the scan and is associated with a poorer prognosis ^2,3. 

CT perfusion

The presence of the spot sign on dynamic-enhancement CT (DECT or CT perfusion) may be an even stronger predictor of haematoma expansion ^4,5, i.e. the most robust factor in predicting outcome ⁸.

MRI

MRI is usually obtained when concern exists that the bleed is from an underlying vascular malformation or neoplasm. Findings depend on the size and age of the bleed (see ageing blood on MRI). 

In cases of primary lobar haemorrhage, multiple small areas of susceptibility-induced signal drop-out may be evident on gradient echo (GRE) or susceptibility weighted (SWI) sequences, in-keeping with previous cerebral microhaemorrhages, suggestive of cerebral amyloid angiopathy.

The presence of single lobar haemorrhage is still part of the Boston criteria for CAA.

Treatment and prognosis

Overall, management does not differ for other causes of intracerebral haemorrhage - please see the article on intracerebral haemorrhage for further discussion ¹⁵.

Notably, neurosurgical intervention currently has mixed evidence in patients with lobar intracerebral haemorrhage. One randomised trial (STICH II) suggested early surgical therapy did not decrease the rate of death or disability at six months ¹³. However, another randomised control trial (ENRICH) showed that minimally invasive haematoma evacuation, within 24 hours of presentation, improved functional outcomes ¹⁷.

Differential diagnosis

The term lobar haemorrhage is often used to denote a primary haemorrhage. As such the differential includes:

• an underlying tumour (e.g. glioblastoma, cerebral metastasis) 

• an underlying vascular malformation (e.g. cerebral arteriovenous malformation)

• haemorrhagic transformation of a cerebral infarct

• haemorrhagic transformation of the venous infarct

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