Intracranial Arterial Dissection

You’ve been diagnosed with an intracranial arterial dissection — what does this mean?

A spontaneous dissection in an intracranial vessel means that the wall of an artery inside the brain has developed an internal “tear.” Blood enters this defect, forms a second channel (a false lumen), and compresses the true arterial lumen.

This may lead either to an ischemic stroke (when flow is reduced or clot forms and embolizes) or to subarachnoid hemorrhage (when the dissection ruptures outward, behaving like a fragile “pseudoaneurysm”). It is a condition that requires prompt, specialized evaluation and management.

What exactly is an intracranial arterial dissection?

In a dissection, an inner-wall defect forms within the artery:

• Blood tracks between layers of the arterial wall, creating a false cavity
• The true lumen narrows → reduced blood flow to the brain
• A thrombus can form at the tear → embolic stroke risk
• In some cases, a pseudoaneurysm or “blister” aneurysm develops, with an extremely thin wall

Intracranial dissections account for a small fraction of head-and-neck dissections, but they are responsible for approximately 3–5% of non-traumatic subarachnoid hemorrhages.

Causes & risk factors

Often there is no single clear cause. Factors associated with higher risk include:

• High blood pressure
• Long-term tobacco use
• Hormonal factors (e.g., oral contraceptives)
• History of migraine
• Recent infection or minor mechanical triggers (severe coughing, sudden neck movement)
• Inherited connective tissue disorders (Ehlers–Danlos, Marfan, ADPKD)
• Fibromuscular dysplasia and other rare arteriopathies

In most cases, the patient is not at fault. What matters is timely recognition and choosing the safest, most effective treatment strategy.

What are the symptoms? Types of dissections

Clinical presentation varies depending on location and dissection phenotype.

Hemorrhagic dissections / blister aneurysms

• Sudden, severe headache (often occipital)
• Nausea, vomiting, photophobia
• Altered level of consciousness
• Signs of subarachnoid hemorrhage similar to aneurysmal rupture

The risk of rebleeding within the first 24 hours is particularly high and carries substantial mortality.

Non-hemorrhagic / ischemic dissections

• Focal neurologic deficits (weakness, speech difficulty, visual disturbance)
• Transient ischemic attacks (TIAs)
• Persistent neck, facial, or head pain
• Cranial neuropathies (e.g., diplopia) due to pseudoaneurysm mass effect

How is it diagnosed and evaluated?

Diagnostic work-up is tailored based on whether hemorrhage or ischemia is the dominant presentation:

• Head CT — first-line test when hemorrhage is suspected; evaluates hydrocephalus and mass effect.
• CT angiography (CTA) — rapid definition of the lesion; useful for urgent planning.
• MRI/MRA — detects ischemic infarcts and can characterize vessel wall/morphology in selected cases.
• Digital subtraction angiography (DSA) — the gold standard; defines the dissection/pseudoaneurysm and can allow immediate endovascular treatment.

In selected cases, hemodynamic assessment (CT/MR perfusion) is performed to estimate ischemia risk if vessel occlusion becomes necessary.

Who needs intervention — and when?

Decisions are individualized and made by a specialized cerebrovascular neurosurgical team. In general:

• All hemorrhagic dissections and blister aneurysms require urgent treatment
• Non-hemorrhagic dissections with recurrent TIAs/strokes despite optimal medical therapy
• Large pseudoaneurysms causing cranial nerve compression or judged to have a high rupture risk
• Cases where anatomy does not allow safe “watchful waiting” with medication alone

For stable, non-hemorrhagic dissections without ongoing symptoms, conservative management with antiplatelet therapy and close follow-up may be appropriate.

What treatment options are available?

Strategy depends on circulation (anterior vs posterior), lesion morphology, rupture status, collateral flow, and the patient’s overall condition.

Endovascular techniques

• Parent vessel occlusion — with coils or balloons when collateral circulation is sufficient.
• Pseudoaneurysm coiling — in selected cases.
• Flow-diverting stents (primarily in the anterior circulation) — but these require dual antiplatelet therapy and are not always suitable in acute hemorrhage.

Microsurgery

• Direct occlusion or occlusion with bypass (EC–IC or in situ) when flow preservation is essential
• Clip reconstruction or wrapping for selected blister aneurysms

What should I expect in the hospital?

Patients with hemorrhagic dissections are managed similarly to those with ruptured aneurysms:

• Admission to an ICU or specialized neurosurgical unit
• Continuous monitoring of blood pressure, respiration, and electrolytes
• Close neurologic assessments and repeat imaging
• Early management of hydrocephalus, vasospasm, and hyponatremia
• Timing and preparation for endovascular or surgical intervention when clinically optimal

In patients with severe vasospasm or significant cerebral swelling, a delayed definitive intervention may be chosen after stabilization, with intensive support in the interim.

Recovery & prognosis

Prognosis is mainly influenced by:

• The severity of the initial hemorrhage or stroke
• Any early rebleeding prior to definitive treatment
• Whether a major vessel had to be sacrificed, and how effectively the brain was protected via bypass or collateral circulation

With modern techniques, a meaningful proportion of patients achieve good functional outcomes. However, this remains a high-risk pathology and requires long-term neurological and imaging follow-up.

How does daily life change afterward?

After stabilization and definitive treatment, we emphasize:

• Excellent long-term blood pressure control
• Permanent smoking cessation
• Lipid and glucose optimization
• Gradual return to work and exercise under team guidance
• Avoidance of activities that sharply raise blood pressure (heavy lifting, extreme stress) for a period of time

Many patients benefit from physiotherapy, speech therapy, or neuropsychological support depending on any residual neurologic deficits.

When should I seek immediate help?

Call emergency services immediately if any of the following occur:

• A sudden, unusually severe “different” headache
• New weakness, numbness, or paralysis of the face/arm/leg
• Difficulty speaking or understanding speech
• Sudden vision loss or double vision
• Seizures or loss of consciousness