Combined conduit score of sinovenous stenosis

The combined conduit score (CCS) is a grading scheme for the assessment of the degree of transverse-sigmoid sinus stenosis in the setting of idiopathic intracranial hypertension. The score was initially developed for ATECO MR venography 1.


Assessment is performed using maximum intensity projection (MIP) reconstructions from gadolinium-enhanced MRV images, as time-of-flight artefacts overestimate stenosis. The initial projections described were RAO, LAO and rotational cine loop MIPs.

Transverse-sigmoid patency
  • 0: discontinuity (gap) or aplastic segment
  • 1: hypoplasia or severe stenosis within a segment of the conduit estimated as <25% of the cross-sectional diameter of the lumen of the distal superior sagittal sinus
  • 2: moderately stenosed segment of the conduit (25–50%) 
  • 3: mildly narrowed segment (50–75%) 
  • 4: no significant narrowing (75–100%)

The grade for each right and left transverse-sigmoid conduit is determined separately. The highest degree from the torcula through to the distal sigmoid sinus determines the score on each side.

Practical points

  1. the sum of the right and left provides the CCS and thus ranges from 0–8, and is often expressed as a sum (e.g. 3 + 2)
    • a score of 4 is a suggested cutoff to define significant stenosis
  2. a combined conduit score can identify patients with idiopathic intracranial hypertension with a sensitivity and specificity of 93%
  3. the ACCS study by Kelly et al. in 2013 suggested all patients with transverse-sigmoid stenosis on MRV should undergo fundoscopy to assess for papilledema 2
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Article information

rID: 56991
Synonyms or Alternate Spellings:
  • Combined conduit score (CCS)

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Cases and figures

  • Case 1: normal venogram
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  • Case 2: normal venogram
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