Terminology for Very Large Pontine Stroke
A very large pontine stroke is best described as a "bilateral pontine infarction" or "bilateral ventrotegmental pontine infarct" when it involves both sides of the pons, which represents the most severe form of pontine stroke with the worst prognosis. 1
Anatomical Classification Based on Size and Location
The terminology for pontine strokes should reflect both the extent and anatomical distribution rather than simply using "large" as a descriptor:
Bilateral Pontine Infarction
- Bilateral pontine syndrome is the specific term used when infarction involves both sides of the pons, presenting with transient consciousness loss, tetraparesis, and acute pseudobulbar palsy 1
- This represents approximately 11% of isolated pontine infarcts and carries the worst prognosis among pontine stroke subtypes 1
- Bilateral ventrotegmental pontine infarct is the more anatomically precise term when both ventral and tegmental structures are affected bilaterally 2
Unilateral Large Pontine Infarctions
- Anteromedial pontine syndrome (58% of cases) involves the ventromedial territory and presents with severe motor deficits, bilateral ataxia, and dysarthria 2, 1
- Anterolateral pontine syndrome (17% of cases) affects the ventrolateral territory with motor and sensory deficits plus tegmental signs 1
- Unilateral multiple pontine infarcts (4% of cases) involve multiple territories on one side with severe sensorimotor deficits 1
Size Criteria and Stroke Mechanism
Pontine infarcts >11.8 mm in diameter suggest parent artery disease (basilar artery branch disease) rather than small vessel disease, which has important implications for etiology and management 3:
- Lesions >11.8 mm are more likely due to basilar artery branch disease (BABD), the most common cause at 39-44% of pontine strokes 2, 1, 3
- BABD is particularly associated with large ventral infarcts, severe clinical symptoms, progressive or fluctuating course, and risk of local recurrence 2
- Smaller lesions (<11.8 mm) are more consistent with small-artery disease (SAD) from lipohyalinosis, accounting for 21-25% of cases 2, 1
Clinical Context and Prognosis
Warning About Locked-In Syndrome
- Locked-in syndrome is the catastrophic presentation of bilateral pontine infarcts with proximal basilar occlusion, where patients retain consciousness but have complete paralysis except for vertical eye movements 4
- This represents the most severe end of the spectrum and should be explicitly mentioned when describing very large pontine strokes
Prognostic Implications
- Bilateral pontine lesions have poor outcomes compared to unilateral infarcts, where two-thirds of patients achieve good recovery 2, 1
- Large ventral infarcts are associated with worse outcomes than tegmental or small lacunar infarcts 2
Common Pitfall to Avoid
Do not use the term "malignant pontine infarction" as an analogy to "malignant MCA infarction"—this terminology is not established in the literature for posterior circulation strokes 5. The guidelines specifically define malignant infarction for MCA territory strokes with mass effect and herniation risk, which has different pathophysiology than pontine strokes 5.
Instead, use anatomically descriptive terms (bilateral pontine infarction, extensive basilar territory infarction) combined with etiologic classification (basilar artery branch disease, basilar artery occlusion) for precise communication 2, 1.