Convexal Subarachnoid Hemorrhage (cSAH)

KEY FACTS

TERMINOLOGY

• Unique type of subarachnoid hemorrhage (SAH)

○ Localized to sulci over top ("convexity") of brain

IMAGING

• NECT: Hyperdensity in 1 or several adjacent dorsolateral

convexity sulci

○ Spares basal, perimesencephalic cisterns

• MR

○ Sulcal cerebrospinal fluid (CSF) replaced by isointense

fluid in convexity sulcus ("dirty CSF")

○ Hyperintense sulcus on FLAIR

○ GRE, SWI show "blooming" in affected sulci

TOP DIFFERENTIAL DIAGNOSES

• Aneurysmal SAH

• Perimesencephalic nonaneurysmal SAH

• Traumatic SAH

PATHOLOGY

• Most common etiology varies with age

○ Elderly patients: Amyloid angiopathy, venous

thrombosis, vasculitis

○ Middle aged: Reversible cerebral vasoconstriction

syndrome (RCVS), vasculitis, vein thrombosis

○ Young adults, children: Drugs, vasculitis, vein/dural sinus

thrombosis

CLINICAL ISSUES

• 7% of all spontaneous (nontraumatic) SAH

• Most common: Middle-aged women

• Presentation varies with age

○ < 60 years of age: Sudden "thunderclap" headache (e.g.,

RCVS)

○ > 60 years of age: Transient sensory, motor symptoms,

less intense headache (cerebral amyloid angiopathy)

(Left) Graphic of brain seen

from above shows convexal

subarachnoid hemorrhage in

purple affecting adjacent sulci

but sparing the basal cisterns.

(Right) Axial NECT in a 28-

year-old woman with severe

headache following delivery

shows focal subarachnoid

hemorrhage ſt over the right

cerebral convexity.

(Left) Axial T1WI MR in the

same patient shows "dirty"

fluid filling, effacing the

normal sulcal cerebrospinal

fluid (CSF) in the right

convexity sulci ſt (compare to

normal hypointense signal

intensity in the contralateral

sulci ﬇). (Right) Axial FLAIR

MR in the same patient shows

hyperintense right convexity

sulci ſt (contrast with the

normal suppressed

hypointense CSF over the left

convexity). Postpartum

vasculopathy was diagnosed

at DSA (not shown).

Brain: Pathology-Based Diagnoses: Malformations,

Trauma, and Stroke

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