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Clinical Applications - Vasospasm

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Transcranial Doppler is widely and commonly used for diagnosis and follow up of vasospasm in neurosurgery departments and neuro-intensive care units. The main reason for vasospasm is bleeding in the subarachnoid spaces, TCD examinations of patients with subarachnoid hemorrhage (SAH) are clinically relevant if they are performed daily (sometimes twice a day) or once in two days during the critical period for the development of vasospasm (3-15 days after SAH).

Figure 1: BA Vasospasm

Cerebral Vasospasm is the narrowing of the major intracranial arteries, by tightening or spasm of the muscles within the vessel's wall. This narrowing imposes a restriction in the volume of blood flowing through the vessel. Severe cerebral vasospasm can leads to a complete vasoconstriction which leads to ischemia and brain cells necrosis. It usually starts on Days 3-5 from the event that triggered it, it gets to maximal narrowing of the arterial lumen on Days 5-14, and it slowly resolves over 2-4 weeks. As for clinical symptoms we can see an insidious onset of confusion and decreased level of consciousness, followed by focal motor and/or speech impairment which develop parallel to the development of the cerebral vasospasm.

There are several clinical situations that can cause cerebral vasospasm, as we mentioned earlier, the main reason is subarachnoid hemorrhage (SAH) due to aneurisms, arterio venous malformation (AVM), traumatic head injury, or other unknown origin. Other situations are: Eclampsia, postpartum encephalopathy, Pituitary surgery, pituitary stroke, Migraine, and Drugs like cocaine and bromocriptine.

Figure 2: Left ACA Vasospasm

Trancranial Doppler is used for cerebral vasospasm diagnosis and follow up according to the following criteria:

  • Flow velocities:
    Intracranial ICA, MCA, ACA ≥130 cm/sec
    VA ≥80 cm/sec
    BA ≥ 90 cm/sec
    PCA ≥110 cm/sec                                
  • MFV MCA/MFV extracranial ICA >3 (Lindegaard ratio)
  • MFV BA/MFV extracranial VA >2
  • Changes in the Doppler waveform: decrease of pulsatility index (PI), signs of turbulence, fluttered envelope
  • A rapid early rise in flow velocities (more than 25% per day)
  • In severe vasospasm: decrease of flow velocities with progressive weakening of the signal

The advantages of using TCD for cerebral vasospasm diagnosis are:

  • Noninvasive
  • Bedside examination
  • Cost-effective
  • High sensitivity and specificity
  • Comfortable, and easily repeatable examination
  • Enables early detection
  • Enables easy follow up for vasospasm

TCD is the only noninvasive technique with high sensitivity and specificity, it is a quick and easy to use tool for cerebral vasospasm diagnosis and follow up.

Figure 3: Left MCA Vasospasm