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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5783_Библиотеки_им_академика_М_И_Перельмана.pdf
254
C. N. Rodríguez and D. Pugin
a
Fig. 14.2 (a) Schema: Circle of Willis; (1) internal carotid artery (ICA), (2) middle cerebral artery
(MCA) M1-segment and M2 segment, (3) anterior communicating artery (AcomA), (4) anterior
communicating artery (ACA) A1-segment, (5) posterior communicating artery (PcomA), (6) posterior cerebral artery (PCA) P1-segment and P2-segment, (7) vertebral arteries (VA) V4-segments,
(8) postero-inferior cerebellar artery (PICA), and (9) basilar artery (BA). (b) TCCS: Circle of
Willis by mesencephalic plane through transtemporal acoustic window; ACA: anterior cerebral
artery (A1 segment), MCA middle cerebral artery (M1 segment), PCA posterior cerebral artery
(P1 segment), MCAc contralateral middle cerebral artery and (1) mesencephalon
b
14.3.1 Anterior Circulation
14.3.1.1 Carotid System
• Internal Carotid Artery (ICA)
(a) Carotid siphon
(b) Ophthalmic artery
(c) Middle Cerebral Artery (MCA)
c.1 M1 Segment
c.2 M2 Segment
c.3 M3 Segment
(d) Anterior Cerebral Artery (ACA)
d.1 A1 Segment
d.2 A2 Segment
(e) Posterior communicating artery (PcomA)
14 Neurosonology in ICU: Transcranial Color-Coded Duplex Sonography (TCCS…
14.3.2 Posterior Circulation
14.3.2.1 Vertebro-Basilar System
• Vertebral Artery (VA)
(a) V1 segment
(b) V2 segment
(c) V3 segment
(d) V4 segment
Most common insonated through transforaminal window.
• Basilar Artery (BA)
(a) Posterior Cerebral Artery (PCA)
a.1 P1 segment
a.2 P2 segment
• Postero-inferior Cerebellar Artery (PICA)
Note that the Circle of Willis is incomplete in 40–65% of population [7–9].
14.4 TCCS: Brain Parenchyma andNon-vascular Structures
255
The milestones displayed regularly with identication rates of >75% are as follows
[10, 11]:
Transcranial Ultrasonography: B-Mode (Gray Scale)
1. Sphenoid bone/Petrosal bone
2. Medial Cerebral Fossa
3. Cerebellum
4. Mesencephalon
5. Thalamus
6. Pineal gland
7. Frontal horns of lateral ventricles
8. Choroidal plexus
9. Third ventricle
10. Cerebral midline
11. Intra-axial/extra-axial collections
There are intracerebral anatomical structures such as medulla oblongata, fourth
ventricle, cerebellar structures, insula, frontal, parietal, and occipital lobes that can
be visualized with greater difculty except in craniectomized patients [10].
There is a good correlation between the computed tomography (CT) and the
transcranial color-coded duplex sonography (TCCS) when studying and interpreting the anatomical structures of the brain parenchyma in non-craniectomized
256
patients: third ventricle (and its displacement), midline shift, perimesencephalic cistern, and Sylvian ssure [12, 13]. This correlation is better between CT and TCCS
in craniectomized patients, where lateral ventricles, hyper- or hypodense lesions,
and the location of the intraventricular catheter can be seen [14].
C. N. Rodríguez and D. Pugin
14.5 TCCS: Examiner Considerations
The ultrasonography examination in the intensive care unit or the emergency department presents unique characteristics as the patients are less mobile, often intubated,
sometimes hemodynamically instable. TCCS needs to be completed quickly.
Furthermore, different parameters may inuence the blood ow velocities such as
fever, anemia, brady or tachycardia, and hypo- or hypercapnia, and must be recorded
at the same time to allow an integrative analysis of the measures.
1. Mobility of the Patient and Clinical Context?
Patients with suspected cervical lesions or intubated and patients with intracranial hypertension cannot be mobilized freely, and the TCCS exam could be
limited. Usually, the temporal window is accessible, even if the patient’s head
needs to be maintained in a neutral position. It is up to the treating physicians to
evaluate the clinical situation and dene the best strategy.
2. Time to Conduct the Study
In a trained professional, TCCS requires usually between 20 and 45 minutes
for a complete and comprehensive evaluation of the different elements (parenchyma, blood ow velocities of the different arteries of interest) [22–24].
14.6 TCCS: Acoustic Windows
There are ve insonation acoustic windows for TCCS approach:
1. Transtemporal
2. Transforaminal (suboccipital)
3. Transorbital
4. Submandibular
5. Frontal
In general, the patient is examined in supine position (with the exception of the
evaluation through the suboccipital window) with the head preferably aligned with
the body and with the head at 30° (whenever possible). The operator is located
behind the patient’s head (sitting or standing) or on patient’s side.
The study of TCCS in the intensive care unit requires time and dedication on the
part of the operator to obtain reliable information, often dedicating 30 to 45minutes
per examination depending on the critical pathology of the patient [22–24].
14 Neurosonology in ICU: Transcranial Color-Coded Duplex Sonography (TCCS…
Consider that TCCS and the “blind” TCD techniques are complementary exams
that require time and dedication if a reliable and complete interpretation of them is
required. In the TCD, the insonation angle of the vessels and the ultrasound beam is
unknown. There is no visual orientation, so the ow and its speed can be underestimated, but a small angle of insonation is presumed (0°–30°) [2]. The angle of
insonation during the development of the TCCS study is very important when interpreting the results. It is necessary to be able to maintain an angle of insonation <60°
for an optimal interpretation of the ow velocity in cerebral arterial vessels [25–27].
257
14.7 TCCS: Examination Protocol
The transcranial color-coded duplex sonography (TCCS) requires the use of a lowfrequency transducer (1.75–3.5MHz), as cardiac transducers. This probe is adequate for penetration of the temporal skull and enables the visualization of the
cerebral parenchyma (B-mode) and the evaluation of cerebral arteries through the
Doppler signal [15, 16].
To evaluate the optic nerve sheath diameter, the vascular probe should be used
(5–12MHz).
As the optic nerve is subject to the same pressure changes as the intracranial compartment [17, 18], the optic nerve sheath diameter has an anterior enlargement in case
of increased intracranial pressure. Several studies have found a correlation between
optic nerve sheath diameter and increased intracranial pressure (ICP) [19–21].
The upper limit of normal value of optic nerve sheath diameter is 5 mm if
recorded as described below. With this cut-off for intracranial hypertension, the
specicity is 93% and negative predictive value 100% [21].
14.7.1 Transtemporal Acoustic Window Examination
(Axial Planes)
The transtemporal window is most frequently used for insonation in an axial plane
of the arterial vessels. At the 1998 annual meeting of the European Transcranial
Color-Coded Duplex Study Group (TCCS study group), the following exploration
planes were recommended:
1. Mesencephalic plane (Figs.14.3 and 14.4)
2. Diencephalic plane (Fig.14.5)
3. Ventricular plane (Cella media) (Fig.14.6)
4. Upper pontine plane (Fig.14.8b)
5. Lower pontine plane (Fig.14.8a)
258
C. N. Rodríguez and D. Pugin
a
Fig. 14.3 (a) Mesencephalic plane by TCCS through transtemporal acoustic window. M: mesencephalon, CS: contralateral skull. (b) Circle of Willis. M1 M1 segment of middle cerebral artery
(MCA), M2 M2 segment of MCA, M1c contralateral M1 segment of MCA, ACA A1 segment,
PCA P1 segment, PCAc contralateral P1 segment, M mesencephalon, and CS:contralateral skull
a
b
b
Fig. 14.4 (a) Mesencephalic plane by TCCS through transtemporal acoustic window; M: mesencephalon (¨Buttery¨), (Arrow) contralateral skull. (b) Brain TC-scan; M: mesencephalon, (1)
ambiens cistern and (2) quadrigeminal cistern
This is the main window of insonation when we start a study with the transcranial color-coded duplex sonography (TCCS) and the gray-scale brain ultrasound
(B-Mode). It allows a direct visualization of the anatomical references and therefore
a correct identication of the structures (carotid arterial system and main parenchymal structures).
14.7.1.1 Considerations
Recommended Depth: 140–160mm
Which allows a direct visualization of the contralateral skull.
14 Neurosonology in ICU: Transcranial Color-Coded Duplex Sonography (TCCS…
259
a
Fig. 14.5 (a) Diencephalic plane by TCCS through transtemporal acoustic window: (1) Thalamus.
(2) Pineal gland, (yellow arrow) 3rd ventricle and (green arrow) contralateral skull. (b) Brain MRI:
(1) Thalamus, (yellow arrow) 3rd ventricle, (dotted line) ultrasound beam through transtemporal
window and (green arrow) contralateral skull
a
b
b
Fig. 14.6 (a) Ventricular plane by TCCS through transtemporal acoustic window: (1) anterior
horns of lateral ventricles, (arrow) contralateral skull. (b) Brain MRI: (1) anterior horns of lateral
ventricles and ultrasound beam (dotted line)
Doppler: (Convention)
• Blue color: Flow away from transducer.
• Red color: Flow forward to the transducer.
We suggest the following protocol order so as not to leave any detail unstudied:
(a) Transducer: (Probe)
• Cardiac low-frequency probe (1.75–3.5MHz)
(b) Patient Positioning:
• Supine position with the head at a 30° angle, aligned with the body
• (Not always possible in critically ill patients)
260
Fig. 14.7 Scheme:
Transtemporal acoustic
window. F frontal, A
anterior, M mean, and P
posterior position
C. N. Rodríguez and D. Pugin
(c) Depth:
• 14–16cm
• (Allows the direct visualization of the contralateral skull)
(d) Insonation Window: Transtemporal Acoustic Window:
• With the probe mark looking forward
• Position the probe in front of the tragus in the temporal bone above the
zygomatic arch (Fig.14.7)
(e) B-Mode:
• Localize the contralateral skull
• Localize the cerebral peduncles (mesencephalon: Buttery-shaped cerebral
peduncles) (Figs.14.3 and 14.4)
(f) Color Doppler: Location of Circle of Willis: (Fig.14.2)
• Start the color-coded Doppler (red color–blue color)
• Identify the different arteries of the circle of Willis around mesencephalic
brainstem
(g) Color Doppler: Location of the Ipsilateral Middle Cerebral Artery (MCA):
• Start the color-coded Doppler (red color–blue color)
14 Neurosonology in ICU: Transcranial Color-Coded Duplex Sonography (TCCS…
• Identify the M1 segment of MCA (horizontal segment) (Fig.14.2)
(h) Arterial Blood Flow Velocities (PW Doppler): Doppler Spectrum Analysis:
• Place the pulsed Doppler (PW) on the M1 segment of MCA (proximal)
• The PW Doppler allows to obtain the spectral Doppler wave and the ow
velocities (MFV /PSV/EDV) of each insonated vessel
(i) Identify Other Intracerebral Arteries of the Circle of Willis: [28]
Anterior Circulation:
• Identication: (color Doppler) A1 segment of ipsilateral ACA
• (They can be very useful for the evaluation of collateral circulation in case
of an occlusive disease) [29]
• Identication: (color Doppler) Contralateral M1 segment of MCA
• (sometimes is possible)
• Identication: (color Doppler) AcomA and PcomA
(j) Identify Other Intracerebral Arteries of the Circle of Willis:
Posterior Circulation:
• It is usually not identied in the same plane of the MCA; it is therefore
required to tilt the transducer caudally.
• Identication: (Color Doppler) P1 and P2 segments of PCA
• [Ipsilateral vessels: P1 segment (red color) and P2 (blue color)].
• Sometimes a blue non-pulsatile signal could be identied, next to the P2
segment. It is the Basal vein of Rosenthal [30].
261
(k) Tilt the Transducer 10º Cephalic from the Mesencephalic Plane: Diencephalic
Plane (Thalamic Plane):
• B-Mode: Midline
• Visualization of the third ventricle (linear hyperechoic structure)
• B-Mode: Thalamus: Next to the third ventricle (bilateral hypoechoic
structures)
• B-Mode: Pineal gland: A posterior calcied structure (hyperechoic structure)
• Color Doppler: M2 and M3 segments of ipsilateral MCA. A2 segment of ACA
(l) Tilt the Transducer 10° cephalic from thalamic plane: Ventricular plane (Cella
Media plane): [31]
• B-Mode: Frontal horns of the lateral ventricles (Hypoechoic bilateral
structures)
• Color Doppler: M3 segment of ipsilateral MCA
(m) B-Mode and color Doppler: Lowering the insonation angle by 10° from the
mesencephalic plane: Pontine plane: (Fig.14.8b)
• B-Mode: (Anteriorly) Sphenoid bone
262
C. N. Rodríguez and D. Pugin
a
Fig. 14.8 (a) Lower pontine plane through transtemporal window by TCCS approach: (red line)
petrosal bone and (green line) sphenoid bone. (b) Upper pontine plane through transtemporal
window by TCCS approach: (CS) contralateral skull, (PF) posterior fossa, (red line) petrosal bone,
and (green line) sphenoid bone
b
• B-Mode: (Posteriorly) Petrosal bone
• Sphenoid + Petrosal bones: Forms middle temporal fossa
• Cerebellum: Hypoechoic structure
• Color Doppler: ICA-Siphon and ophthalmic artery (OA)
(n) B-Mode and color Doppler: Lowering the insonation angle by 10° from the
upper pontine plane: Lower Pontine plane: (Fig.14.8a)
• B-Mode: (Anteriorly) Sphenoid bone
• B-Mode: (Posteriorly) Petrosal bone
• Color Doppler: C1 segment–ICA
14.7.2 Transtemporal Acoustic Window Examination (Coronal Planes)
The transtemporal window is most frequently used for insonation. The coronal
planes may be a complementary ultrasound view to insonate vessels with difcult access.
2.1 Anterior Coronal Plane
2.2 Posterior Coronal Plane
We suggest the following protocol order so as not to leave any detail unstudied:
(a) Transducer: (Probe)
• Cardiac low-frequency probe (1.75–3.5MHz)
(b) Patient Positioning:
• Supine position with the head at a 30° angle, aligned with the body
14 Neurosonology in ICU: Transcranial Color-Coded Duplex Sonography (TCCS…
263
a
Fig. 14.9 (a) Scheme: Anatomical coronal section; (1) C1 segment of ICA, (2) Frontal horns of
lateral ventricles and (Yellow Dotted line) coronal ultrasound beam. (b) Anterior coronal plane
through transtemporal window by TCCS approach: (1)(2) frontal horns of lateral ventricles, (3)
brain parenchyma proximal to the probe, (4) contralateral skull. (A) Yellow arrows: carotid Groove
of the sphenoid bone (C1 segment of Internal carotid artery (ICA))
b
• (Not always possible in critically ill patients)
(c) Depth:
• 14–16cm
• (Allows the direct visualization of the contralateral skull)
(d) Rotate the Transducer 90° from the Mesencephalic Plane: Anterior Coronal
Plane: (Fig.14.9)
• B-Mode: Frontal horns of the lateral ventricles (Hypoechoic structures)
• B-Mode: Carotid groove of the sphenoid bone
• Color Doppler: Terminal internal carotid artery (C1 segment of ICA)
• Color Doppler: Carotid siphon: Can be visualized more completely with the
combination of two planes: a transtemporal axial and coronal approach
(e) Rotate the transducer by 90° from the transtemporal axial plane, once visual-
ized P1–P2 (PCA): Posterior coronal plane
• Color Doppler: Top of the basilar artery (BA) [32]
14.7.3 Transoccipital (Transnuchal/Transforaminal) Acoustic Window Examination
This acoustic window is the same to insonate the vertebro-basilar arterial system by
TCD or TCCS (Figs.14.10 and 14.11).
We suggest the following protocol order so as not to leave any detail unstudied
of vertebro-basilar system.