Nontraumatic convexal subarachnoid hemorrhage (cSAH)

Created 06/04/2021, last revision 02/12/2023


  • non-traumatic spontaneous subarachnoid hemorrhage at the convexity (non-traumatic convexal SAH – cSAH) is defined as a collection of blood in one or more adjacent sulci, in the absence of SAH in another localization
  • it is relatively rare, but the etiological DDx is quite broad

Clinical presentation

  • severe headache typical for classic SAH is usually not present [Beitzke, 2011]
    • headaches are generally present in cerebral venous thrombosis, RCVS, and PRES
  • transient focal symptoms (paresthesias, paresis) are frequent, which leads to suspicion of stroke/TIA (cSAH belongs to stroke mimics)
    • the etiopathogenesis of transient symptoms is unclear; cortical spreading depression triggered by blood in the SA space is considered [Beitzke, 2011]

Diagnostic evaluation

Computed tomography

  • the primary diagnostic method
  • a finding of sulcal hyperdensity leads to the indication of CTA (both arterial and venous phases)
    • CT sensitivity is approx. 90% in the acute phase but decreases quickly with time (the lesion becomes isodense)
  • given the wide DDx, it is advisable to add an MRI

Magnetic resonance imaging

  • perform the following sequences:
    • FLAIR
    • GRE or SWI
    • DWI+ADC
    • 3D TOF MRA + MR venography
    • T1 and T1 C+
  • FLAIR is highly sensitive to lesions in the subarachnoid space; cSAH appears as a hyperintense band
  • in DDx of cSAH exclude:
    • meningitis
    • leptomeningeal metastases (LMM) and leptomeningeal melanosis
    • post status epilepticus lesions
    • previous contrast examination with gadolinium
    • artifact
  • FLAIR further reveals other typical structural changes in the parenchyma (e.g., PRES, etc.)
  • GRE/SWI – confirms the hemorrhagic nature of sulcal hyperintensities and may also help in the detection of older hemorrhages or venous thrombosis
Non-traumatic convexal SAH


Content available only for logged-in subscribers (registration will be available soon)

Differential diagnosis

  • traumatic SAH
    • history of trauma
    • usually, a more significant extent of SAH in imaging methods
    • concurrent contusions, sometimes only seen on a follow-up CT scan
    • skull bone trauma is visible in the bone window
  • cortical laminar necrosis
    • associated with hyperintense lesions on MR DWI
  • leptomeningeal metastases

You cannot copy content of this page

Send this to a friend
you may find this topic useful:

Nontraumatic convexal subarachnoid hemorrhage