TCD/TCCD vasospasm monitoring

Created 31/03/2021, last revision 01/08/2023

vasospasm is a contraction of the muscular wall of an artery, resulting in its stenosis and reduced flow
the prevalence of vasospasms (VSP) following SAH is 50-70%
vasospasms in SAH patients occur around day 3-5 and last up to 3-4 weeks
approx. 30% of patients with aneurysmal SAH develop delayed ischemic deficit (DID) (Yamaki, 2019)
- DID is the leading preventable cause of a poor outcome
increased risk of VSP is associated with:
- higher Hunt-Hess and Fisher scores
- baseline blood pressure
- fluid depletion
- low ejection fraction (EF)
the risk of complications increases with the number of arteries involved and with hemodynamically significant spasms

Methods for Vasospasms Detection and Monitoring

Doppler ultrasound (TCCD/TCD)
- optimal bedside, cost-effective and non-invasive method
CT angiography
- CT perfusion imaging (CTP) may help predict DID
MR angiography
- low sensitivity for detection of distal vasospasms
- MR perfusion may help predict DID
digital subtraction angiography (DSA)
- reserved for local endovascular treatment

it is recommended to start the examination on days 2-3 to obtain baseline velocities and then repeat every 24 hours to assess the dynamics
examine:
- PSV, EDV, V_mean
- PI and RI → more here
- to exclude the effect of hyperemia, determine the ACM/ACI ratio (Lindegaard Ratio – LR) – a value of LR >3 indicates spasm
a significant increase in velocity indicates vasospasm [Vora, 1999] [Lindegaard,1988]
- V_mean ≥ 120 cm/s ( ACM, ACA) + LR >3
- V_mean ≥ 80 cm/s (AV)
- Vmean ≥ 85-95 cm/s (AB) + LR > 2.5-3
critical value is ↑ Vmean > 50 cm/s/24 h or > 25%/24 h

Vmean = 1/3 (PSV-EDV)+ EDV

there is no correlation between the severity of vasospasm detected by ultrasound and the clinical course; the development of DID cannot be reliably predicted
a sudden increase in peripheral resistance (PI > 1.5) indicates either distal VSP or decompensated intracranial hypertension if detected in multiple vessels

Vessel	V_mean	Sensitivity/specificity
MCA, ACA	≥ 120 cm/s ≥ 200 cm/s (severe spasm)	88% / 78% 27% / 98%
ICA	≥ 90 cm/s	25 % / 93%
VA BA	≥ 60-80 cm/s ≥ 85-95 cm/s	44% / 79% (60cm/s) 77% / 79% (60 cm/s)
the positive predictive value of angiographic vasospasm in MCA is 87% with Vmean > 200 cm/s the negative predictive value of angiographic vasospasm in MCA is 94% with Vmean < 120 cm/s [Vora, 1999]