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Transkaranielle Messung Intraoperativ Extrakranielle Messung Monitoring Funktionstest Dopplersonographie HAL Image Map Transcranial Operativ Excranial Monitoring Function Test Doppler Sonography HAL Image Map

Vasospasm

Despite re-bleeding, vasospasms are a major complication following subarachnoid haemorrhage (SAH). Incidence of SAH in Germany is approximately 15/100,000 in general population. That equates to 13,000 to 14,000 new bleeding events each year.
In about 2/3 of patients vasospasms of intracranial arteries are detectable. Approximately 1/3 of them suffer from vasospasm caused symptoms, of which in turn 1/3 will die (Dorsch und King, 1994+2011).
The risk to develop vasospasms achieves its maximum between second and tenth day after the event of bleeding. Up to now, the reason, which accounts for the development of vasospasms has not been clarified definitely.



Incidence and relevance
Despite re-bleeding, vasospasms are a major complication following subarachnoid haemorrhage (SAH). Incidence of SAH in Germany is approximately 15/100,000 in general population. That equates to 13,000 to 14,000 new bleeding events each year.
In about 2/3 of patients vasospasms of intracranial arteries are detectable. Approximately 1/3 of them suffer from vasospasm caused symptoms, of which in turn 1/3 will die (Dorsch und King, 1994+2011).
The risk to develop vasospasms achieves its maximum between second and tenth day after the event of bleeding. Up to now, the reason, which accounts for the development of vasospasms has not been clarified definitely.

Vasospasms are luminal vessel narrows, which can cause hypoperfusion of brain parenchyma, which is supplied by the spastic vessel. In case of significant spasm this bears comparison with ischemic stroke.
As for all types of stroke symptoms can be different (e.g. aphasia, hemiplegia, etc.). However, clinical assessment of patients is often complicated due to sedation and mechanical ventilation.

TCD diagnostics
Firstly, diagnosis of subarachnoid haemorrhage itself is usually made by CT scanning (blood located within cerebrospinal fluid spaces (= subarachnoid space). Typical clinical symptoms are never experienced “sharp-shooting” headache and meningism (inability to drop chin to sternum) Definite and certain diagnosis of vasospasm is usually made by Digital Substraction Angiography (DSA) of intracranial arteries, which is considered as gold standard. Even though, CT angiography can give evidence of vasospasm but uses invasive X-ray as well.

Regular measurement of blood flow velocities (BFV) using ultrasound allows to draw conclusions on vascular luminal changes, which is inversely proportional to the BFV and can be frequently repeated bedside since it does not require invasive techniques.

However, knowledge of initial BFV measurements is required, which should optimally be determined immediately after admission.

TCD measurements to detect vasospasm
To detect vasospasms reliably, TCD examinations should been made at least daily within first 10 days after event of bleeding (initially preferably twice a day). Often, absolute BFV are determined to indicate vasospasms. Calculation of the Lindegaard-ratio, which is calculated from BFV in medial cerebral artery and ipsilateral internal carotid artery, (vMCA/vICA) seems to be more suitable.

Values less than 2 point rather to hyperperfusion whereas Lindegaard-ratio higher than 3 indicates vasospasm. A note of caution is necessary if increased intracranial pressure is likely. Increased intracranial pressure correlates with increased peripheral vascular resistance, which causes decrease of flow in the vessels of Circle of Willis.

As far as no other stenosis exist, for MCA following value are useful to detect vasospasms:



Both, for PCA and ACA similarly the same values can be applied, but should be classified about 25% lower than for MCA. However, in these segments even in case of normal blood flow velocities spasms are possible. Provided a good collateralisation by ACOM and PCOM, these spasms will not become haemodynamical relevant, which can even result in decrease of BFV in these segments.
In case of aplasia or hypoplasia of ACOM and/or PCOM (which might be initially know), increased BFV indicate relevant vasospasm as for MCA.

TCD alternatives
Despite TCD blood flow velocities can be derived using transcranial color-coded Doppler ultrasound (TCCD). This technique provides two-dimensional imaging of intracranial vessels as well as an anglecorrected flow measurement. However TCCD underlies a higher rate of inadequate acoustic (ultrasonic) bone windows (10-20% for TCCD vs. 5-10% for TCD referenced by literature).

Recently, NIRS (near infra-red spectroscopy) was investigated for detection of intracerebral vasospasms. NIRS provides measurement of intra-parenchymal oxygen saturation. In contrast to TCD and TCCD, NIRS detects spasms not before they become haemodynamically relevant, which complicates early diagnosis.

Advantages of TCD:
  • Non-invasive, no (little) risks
    • DSA: vascular dissections, bleeding risk, X-ray, iodine contrast agents, etc.
    • CT-A: X-ray, iodine contrast agents.
  • Simple use in the setting of intensive care units
    • Only one device, as small as a laptop
  • Less failure through inadequate acoustic windows
    • TCCD in about 10-20% not applicable
  • Bedside examinations
    • No patient transport necessary => no additional costs for medical employees, less additional time effort
  • Cheap devices, cheap service

Therapy of vasospasms
In former times, a therapy named “Triple H” additional to lipophilic Calcium-Blockers (e.g. Nimodipine) was considered as gold standard to treat vasospasm. Triple-H means hypervolaemia, haemodilution and hypertension.

Due to relevant cardio-pulmonary complications Triple H has become discussed controversial and is currently often applied only in a “modified” manner.
Nowadays, in neuro-vascular centres vasospasms are more frequently treated by angioplasty, which is (up to now?) limited to the major branches of anterior circulation (MCA, ICA, ACA) since posterior circulation is not accessible by catheter techniques by now.
Another treatment option, which is under research, is the intra-arterial injection of Calcium-blockers into the spastic segment (also using catheter techniques).
Downloads

Literature: Monitoring and detection of vasospasm
Open PDF (127 KB)

Atlas of Doppler Sonography

Literaturresearch

download pdfAnästhesie (EN) PDF | 144 KB
download pdfAutoregulation (EN) PDF | 163 KB
download pdfDemenz (EN) PDF | 178 KB
download pdfEmbolie Differenzierung (EN) PDF | 113 KB
download pdfEmbolie Gefäßchirurgie (EN) PDF | 232 KB
download pdfEmbolie Schlaganfallrisiko (EN) PDF | 182 KB
download pdfFunktionelle TCD (EN) PDF | 198 KB
download pdfHirndruck (EN) PDF | 141 KB
download pdfHirntod (EN) PDF | 233 KB
download pdfICU (EN) PDF | 162 KB
download pdfMikrodoppler (EN) PDF | 124 KB
download pdfParkinson (EN) PDF | 85 KB
download pdfReanimation (EN) PDF | 94 KB
download pdfRechts-Links Shunt (EN) PDF | 201 KB
download pdfSichelzellenanämie (EN) PDF | 152 KB
download pdfSonothrombolyse (EN) PDF | 175 KB
download pdfSchlaganfall (EN) PDF | 192 KB
download pdfVasospasmus (EN) PDF | 140 KB
download pdfAnaesthesiology (PDF | 144 KB)
download pdfAutoregulation (PDF | 163 KB)
download pdfDementia (PDF | 178 KB)
download pdfEmboli differentiation (PDF | 113 KB)
download pdfEmboli vascular surgery (PDF | 232 KB)
download pdfEmboli stroke risk (PDF | 182 KB)
download pdfFunctional TCD (PDF | 198 KB)
download pdfBrain pressure (PDF | 141 KB)
download pdfBrain death (PDF | 233 KB)
download pdfICU (PDF | 162 KB)
download pdfMicrodoppler (PDF | 124 KB)
download pdfParkinson (PDF | 85 KB)
download pdfReanimation (PDF | 94 KB)
download pdfRight-Left-Shunt Detection (PDF | 201 KB)
download pdfSickle cell anemia (PDF | 152 KB)
download pdfSonothrombolysis (PDF | 175 KB)
download pdfStroke (PDF | 192 KB)
download pdfVasospasm (PDF | 140 KB)

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