Pontine hemorrhage

Pontine haemorrhagehaemorrhages, are a common form of intracerebral haemorrhage, is most commonly and usually as a result of poorly controlled long-standing hypertension, although also has other causes. When due to long standing poorly-controlled chronic hypertension, the stigmata of chronic hypertensive encephalopathy are often present (see cerebral microhaemorrhages). It It carries a very poor prognosis.

Epidemiology

Primary pontine haemorrhage accounts for ~7.5% (range 5-10%) of haemorrhagic strokes and has an incidence of ~3 per 100,000 people ⁶.

Clinical presentation

Patients present with sudden and precipitous neurological deficits. Depending on the speed at which the haematoma enlarges and the exact location, presentation may include ^1,2:

• decreased level of consciousness (most common)
• long tract signs including tetraparesis
• cranial nerve palsies
• seizures
• Cheyne-Stokes respiration

Pathology

As is the case with penetrating arteries into the basal ganglia, the penetrating arteries from the basilar artery extending into the pons are subject to lipohyalinosis as a result of poorly-controlled hypertension ¹. This renders the vessel wall prone to rupture. The larger paramedian perforators are more commonly the culprit vessels ¹.

Haemorrhage into the pons can of course also be secondary to underlying lesions including:

• vascular malformations
  • cavernous malformations
  • arteriovenous malformations
• tumours
  • neuroepithelial (primary) brain tumours
  • metastases
• central downward transtentorial herniation (Duret haemorrhages)
• supratentorial surgery (remote haemorrhage) ^3,4

Radiographic features

CT

CT of the brain is usually the first, and often the only, investigation obtained upon presentation. Features typical of an acute intraparenchymal haemorrhage are noted, usually located centrally within the pons (on account of the larger paramedian perforators usually being the site of bleeding).

The haematoma more frequently extends in a rostrocaudal direction along the traversing long tracts rather than laterally into the middle cerebellar peduncles. Usually the haematoma does not extend beyond the pontomedullary junction inferiorly and the inferior midbrain superiorly ¹.

These These haematomas frequently rupture into the 4^th ventricle ¹.

In patients who have small volume bleeds and who are thought to possibly have an underlying lesion, MRI may be of use (e.g. identification of a vascular malformation).

Treatment and prognosis

Pontine haemorrhages have a poor prognosis, with large bleeds being almost universally fatal. Open surgical evacuation of the clot is usually not performed, although stereotactic clot aspiration has been advocated by some ⁵.

In smaller haemorrhages, medical management and treatment of hydrocephalus with extraventricular drains may be life saving, however, often with significant residual neurological deficits.

Overall mortality ranges between 30% and 90% ⁶, with the overall volume of the bleed and initial GCS being related to outcome ².

Differential diagnosis

The main differential is between a primary pontine haemorrhage and haemorrhages resulting from underlying lesions (see above). Usually patients present suddenly with severe impairment and the diagnosis is not difficult to make.

In patients where the presentation is not known (e.g. in the exam setting) it is worth considering:

• unruptured/asymptomatic vascular malformations
  • asymptomatic cavernous malformations (these can periodically have small bleeds resulting in repeated symptoms)
  • arteriovenous malformation
    • usually little if any mass effect
    • serpentine irregular density isodense to intravascular blood elsewhere
  • developmental venous anomaly
    • linear, no mass effect
    • density isodense to intravascular blood elsewhere
• haemorrhagic metastases
  • melanoma, renal cell carcinoma, thyroid carcinoma, etc.

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