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Saudi Stroke Association
Saudi
Advisory Group Against Stroke -
(Archive)
The First Saudi Transcranial Doppler
(TCD) Workshop
9 September, 2002, Riyadh, Armed Forces Hospital
Speakers Biographies and Abstracts
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Dr Adnan Awada
Biography:
Dr. Adnan Awada is a consultant neurologist and head of Neurology Division,
Department of Medicine, King Fahd National Guard Hospital. He is the secretary
general of the Saudi Advisory Group Against Stroke.
Dr Adnan Awada was born in Beirut in 1951. After graduating, from the French
University of Beirut I976, Dr Awada completed his Neurology Residency in La
Salpetriere Hospital, Paris. He has obtained a French CES in Neurology in I981
from the University of Paris and Fellowships in EEG and EMG in Paris
(l982-1983). Between I982 and l986 he was a Neurologist in the Stroke Center;
La. Salpetriere Hospital. He was Consultant Neurologist and Assistant
Professor in King Faisal University & King Fahd Hospital of the University,
Dammam, from I988-1991. He also served as Consultant Neurologist in King Fahd
National Guard Hospital and was Clinical Assistant Professor at King Saud
Universally; Riyadh from l99l to I994.
Dr Awada has been serving as the Head, Neurology Section, King Fahd National
Guard Hospital. since 1994. He is a Fellow of the "Societe Francaise de
Neurology" and a Corresponding Fellow of the American Academy of Neurology.
He is a former Secretary of the Editorial Board of "La Revue Neurologique",
Paris and has participated in the 3 major studies on Stroke in The Kingdom
namely: 'The Prevalence of Neurological Diseases in the Community'; 'The
Community Based Stroke Registry of the Eastern Province' and 'The Saudi Stroke
Data Bank'.
Dr. Adnan Awada has published 110 papers, 40 of them about different aspects
of stroke. He has presented 150 papers in local and international Scientific
meetings, 50 of them about stroke.
Lecture:
History of Doppler (8:10-8:30 AM)
Abstract:
Christian Andreas Doppler was an Austrian mathematician who described the
“Doppler effect” in 1842 to explain the changing color of the moving stars.
In 1845, his theory was confirmed for acoustic frequencies by an experience
while musicians on a train were playing notes and others were recording which
notes they were hearing. The 1st practical application of Doppler effect was
after the Titanic Disaster. There was a necessity to develop an underwater
detection system (Sonar) that was refined during the following years and was
of great help for the submarines in World War II.
In 1961, Franklin & colleagues adapted the Doppler technology to blood flow
measurement. The first arteries to be studied were the carotids & lower limbs
arteries. Doppler examination of the extracranial carotid arteries became very
popular in the 1970’s. In the 1980’s, it stated to be coupled with vessel wall
imaging (Echography) and the term of carotid Duplex was used to designate this
combined examination. Finally, in the 1990’s, the problem of the skull being
an obstacle for ultrasounds was resolved and transcranial Doppler became a
routine technique with multiple applications in cerebrovascular disease &
anesthesia.
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Dr Mubarak Shammari
Biography:
Dr. Mubarak Shammari is a consultant of medical physics, Medical Physics
Department, Riyadh Armed Forces Hospital, Riyadh, Saudi Arabia Dr Shammari was born in Hail, Saudi Arabia
in 1957, and completed schoold in Dammam, Saudi Arabia. He is a consultant
medical physicist in Riyadh Military Hospital since 1990. In 19974-1988, he
studied O-Level, A-Level, BSc, MSc and PhD in Medical Physics in UK. He also
received practical training in the field of medical physics at the same
period.
In 1989 he worked as medical physicist and
the head of the science department at King Fahd Medical complex, Dharan, Saudi
Arabia. Dr Shammari joined Riyadh Armed Forces Hospital in 1990 and became in
charge of the technical management of ultrasound system operating in the
hospital and the teaching of ultrasound physics and instrumentation to
radiology residents, echo-cardiographers and sonographers.
Dr Shammari has particular interest in the
field of the application of ultrasound hyperthermia in neoplasm therapy. He
has several publications on the above field and others. He is also a full
member of the American association of physicists in medicine (AAPM).
Lecture:
General principle of Doppler (8:30-8:50 AM)
Abstract:
Wherever there is movement of particles, of
any nature and which can not be directly seen, Doppler's principles comes
into play to detect the velocity of that movement . This applies to gases
moving in tubes at high speed in a chemical factory, fighter jets in the
sky, or overspeeding motorists on the road. The same Doppler's principle is
utilized.
The first description of this principle is
attributed to Johann Christian Doppler (1803-1853), an Austrian Physicist.
Doppler's first descriptions concerned changes in the wavelength of light
and therefore colors of stars as they move relative to earth. Interestingly,
Doppler never extrapolated his postulates to sound waves. The advent of
technology has transformed the practice of modern medicine to become
science-based, where every minute pathological and physiological change can
be measured accurately. Doppler's principle is the scientific tool available
for measuring blood flow characteristics anywhere in the circulatory system
in a simple logical sequence. Cardiologists have been using this tool since
the early sixties to evaluate cardiovascular flow. This valuable tool is now
used by neuro-sonologlists in the investigation of cerebrovascular flow to
assess pathological changes and malformations.
This application, as well as other
technological applications, should be promoted by intensive training and
seminars. It is essential to sharpen skills that are, unfortunately, poor
when it comes to clinical technological applications. This workshop is a
contribution to overcoming this shortcoming.
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Dr Hussien Rabee
Biography:
Dr. Hussien Rabee is a consultant and assistant professor of surgery. He is
the head of Vascular Surgery Division, Department of Surgery, King Khalid
University Hospital, Riyadh, Saudi Arabia.
Following his Bachelor degree in medicine and surgery from
Alexandria University, Egypt in 1984,
Dr Hussien Rabee successfully finished his master degree in surgery in
1989.
Then he became a fellow of the royal college of surgeon in
1995
(Ireland).
In 1996 he received his
medical doctorate in surgery
from
Ain-Shams University, Egypt
and in 1998 he received a
diploma of endovascular
surgery from the
European Society of Vascular Surgery, Liverpool-University of Paris.
Dr Rabee is a member in a number of local and international societies, like
the International Society of Cardiovascular Surgery and the
European Society Of Vascular & Endovascular Surgery.
He is currently the head of the vascular division in the Department of
Surgery, King Khalid University Hospital in Riyadh.
Dr Rabee is a very active vascular surgeon. He conducts almost 20-30 carotid
endarterectomies, 30-40 aortic procedures and 100 bypass surgeries annually.
Besides his clinical work, Dr Rabee has many publications on different issues
regarding peripheral vascular diseases. Also he has been involved in large
number of local and international meetings, workshops and symposia as guest
speaker. Also, he has been involved in
arranging and conducting different workshops, seminars and symposia on
vascular diseases topics in the Kingdom of Saudi Arabia
Lecture:
Clinical applications of Doppler (8:50-9:10 AM)
Abstract:
Doppler ultrasonic waves are commonly used in a wide range of vascular
disorders. In venous diseases, the phasic uni-directional and augmented flow
is helpful to assess the patency and the competency of venous blood flow.
Ankle/ Brachial Index (ABI) is highly reliable in detecting peripheral
vascular diseases. Duplex scan is very successful tool in imaging venous and
arterial trees. Peaked systolic velocities are the mile stone in identifying
patients at risk of developing strokes due to significant carotid artery
diseases. Doppler guided compression has been found to be effective reliable
in treating false aneurysms. Doppler is invaluable method in pre and post
endovascular monitoring. Nowadays, Vascular Lab is essential in the daily
vascular procedures.
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Dr Michael Daffertshofer
Biography:
Dr. Micheal Daffertshofer is an associate professor and consultant
neurologist, Neurology Clinic, Mannheim, University of Heidelberg, Heidelberg,
Germany.
Dr Daffetshiofer finished his initial medical education in 1986 from Heinrich
Heine University in Düsseldorf. Then, he worked at the same university as a
neurology in training for three years. In 1992, he moved to Heidelberg
University and worked in Klinikum Mannheim. He became a senior registrar in
neurology in 1994 and became an associate professor in 1997.
Dr Daffertshofer is mainly interested in transcranial ultrasound. He has many
papers published in this field. The topics of his publications are numerous
and includ:
Clinical ultrasound validation: comparison to angiography, changes of CBFV
during the night sleep, cerebral autoregulation, vaso-neuronal coupling,
Doppler monitoring, volume flow measurement, 3D-ultrasonography, Echo-contrast
agents, harmonic imaging, PFO-detection with TCD, HITS detection with TCD,
follow-up of patients with asymptomatic carotid stenosis, follow-up of
patients with symptomatic and asymptomatic intracranial arterial stenosis and
follow-up of patients suffering from stroke having a PFO. He also has
experimental work including: gait disorder in patients with subcortical
vascular encephalopathy, early signs of arteriosclerosis in dogs, CBFV
reduction after MCA occlusion in rabbits, neuronal plasticity in the motor
system after peripheral amputation, value of sympathetic nskin response in the
evaluation of the autonomic nervous system and teleradiology in neurology.
Besides his clinical and research work, Dr Daffertshofer is
a member in a large number of medical societies and organizations.
Lecture:
Cerebrovascular dynamics (9:30-9:50 AM)
Abstract:
Transcranial Doppler (TCD) as a method for the investigation of lumen
narrowing (or widening) within the insonated vascular segment is well known.
By careful analysis of flow pattern TCD, as well as by utilizing stimulation
techniques TCD can also illuminate general or local physiology and
pathophysiology of cerebral hemodynamics. Since the cerebral blood flow
velocity in the large brain supplying artery, which is measured by TCD,
perfectly reflects cerebral blood flow (CBF) TCD can be used 1.) to monitor
qualitatively cerebrovascular resistance (i.e. increased in the case of
elevated intracranial pressure or decreased in encephalitis); 2.) to
illuminate cerebrovascular reserve capacity by analyzing flow changes to
either hypo- as well as hypercapnia or by administration of acetazolamide
(i.e. to uncover exhaustion of collateral blood supply distal to high grade
arterial obstruction); 3.) to measure cerebral autoregulation due to blood
pressure alterations (i.e. in brain trauma or patients suffering from syncope)
and 4.) to do vasoneuronal testing (i.e. altered in migraine, to predict the
dominant hemisphere as a screening before neurosurgery).
Lecture:
Functional TCD (11:15-11:35 AM)
Abstract:
TCD has a high temporal resolution, is non-invasive and can be used in a
bedside setting. For which it is a perfect monitoring tool. Monitoring of CBFV
can be used to measure recanalisation rate and time in cerebrovascular
disease, it can be useful in vascular surgery particularly in carotid surgery
and of course in carotid neurointervention. Apart from monitoring CBFV values
which indicate either lumen narrowing in SAH patients or critical decrease of
perfusion during vascular interventions. TCD monitoring also enables detection
of microembolic signals (MES), which are characterized by high intensity
transient signals (HITS) within the flow velocity spectrum. Detection of those
MES has been shown to be highly predictive for thrombosis consequence
secondary re-occlusion after neurovascular interventions and therefore can be
used to gain secondary prophylaxis after neurovascular interventions. That may
also be true for vascular patients and giving emboli detection the potential
to be a further decision tool to decide which patient will benefit most from
surgery and in which patients secondary prophylaxis with drugs is more
appropriate. Moreover some studies suggest to use TCD monitoring to optimize
platelet inhibition and anticoagulation by testing for MES. Introducing
contrast agents not passing the lung TCD enables testing for right-to-left
shunt with similar validity as transesophageal echocardiography. It cannot,
however, measure the size and dimensions of a patent foramen ovale but in
contrast to the TEE can also detect right-to-left shunts beyond the heart.
This method is particularly helpful in patients unable or unwilling to swallow
the TEE probe.
Lecture:
TCD in the future (11:35-11:55 AM)
Abstract:
Transcranial Doppler has already been established for the diagnosis and
particularly monitoring of obstructive arterial disease of the large brain
supplying arteries and of hemodynamic aspects of brain vasculature. Moreover
it is unique for detecting microembolic events and it is useful for testing
vasoneuronal coupling. Its major advantages are to be easily available, to be
easy to use and to be able to be repeated unlimitedly. In comparison to other
vascular diagnostics it has disadvantages in local resolution but compared to
angiography, magnetic resonance angiography (MRA), computer tomography
angiogram (CTA), positron emission tomography (PET) or single photon emission
computer tomography (SPECT) has the highest temporal resolution. It is of
course limited in cases with a poor bone window and for that TCD is presently
not a technique-for-all but is a perfect tool in a state-of-the art multimodal
approach for the diagnosis of cerebrovascular diseases.
Since combination of TCD with B-mode ultrasound imaging –transcranial color
coded duplex (TCCD) – actually simplify vessel identification and give some
additional topographical information, the rapid increase in B-mode image
quality and resolution now enable morphological imaging with ultrasound for
the first time. This increased imaging quality already provoked studies
analyzing the capabilities of ultrasound to identify intracerebral bleeding,
tumors or other mass effects. Other studies describe diagnostic features in US
brain imaging in Parkinson’s disease as well as neurodegenerative disease.
The introduction of US contrast agents will further facilitate not only
structural image capacities but will also increase the hemodynamic capacities
of the US. Using contrast agents enable perfusion measurement with ultrasound
and therefore establishes an initial method for monitoring perfusion.
The most exciting aspects of ultrasound however are the recently recognized
therapeutical aspects. Despite general knowledge about therapeutical aspects
of US since years, the use of the therapeutical capacities of US has until
recently not been studied for the brain. US itself induces thrombolysis at
higher energy levels and enhances enzymatic thrombolysis with rt-PA even at
diagnostic power levels. It is known that US leads to neo angiogenesis and
also leads to selective gene activation depending on the specific US
characteristics. When US contrast agents were given these “microbubbles” they
cracked when passing the US-beam. This effect is now the most promising
strategy for developing local drug delivery which may revolutionize several
neurological treatment areas.
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Dr Mona Al-Shahed
Biography:
Dr Shahed gained the Fellowship of the Royal College of Radiologists (London
UK) in 1990 at RKH. She is currently the Deputy Director of Radiology and
Imaging, and Senior Consultant Radiologist at Riyadh Armed Forces Hospital.
Dr Al Shahed has considerable experience in all branches of Radiology, but has
specific interest in CT, Ultrasound, Doppler and Pediatric Radiology. She is
the Department of Radiology and Imaging representative and an integral art the
pioneering live liver donor transplant program since its establishment in
1998. She also participate in Adult Radiology including MRI, Musculoskeletal
CT, Ultrasound Mammography, Mammography and Radiology.
Dr Al Shahed is actively involved in the Saudi Board Residency Training
Program and provides regular tutorials and clinical meetings within the
department.
Lecture:
Extracranial sonographic applications (9:50-10-10 AM)
Abstract:
Stroke is the
most common and disabling
neurologic disorder in the elderly population worldwide.
It is estimated that 80% of all reported strokes are due to ischemic
causes, which include thrombotic, embolic and stenotic disorder. The remaining
20% are haemorrhagic in origin.
Prevention of stroke remains the best line
of treatment.
Because more
than 50%
of strokes
are due
to carotid arteriosclerotic
disease, carotid ultrasound becomes an important imaging modality to identify
disease that may be a potential cause of stroke.
Duplex ultrasound has become a widely used means of detecting and
characterizing carotid arteriosclerosis disease.
Duplex carotid evaluation involves high resolution imaging and
characterization of carotid plaque, as well as quantitative Doppler spectral
analysis to determine the presence and
the degree
of flow restriction.
Modern ultrasound
equipments combine gray-scale
technology with
visual display
of color
and the
velocity information of spectral Doppler ultrasound, the spectral
examination remains the primary method through which stenoses in the internal
carotid artery are quantified. Most frequently used Doppler parameters for the
quantitative assessment include peak systolic velocity (PSV) and end diastolic
velocity (EDV), in the internal carotid artery (ICA) and in the common carotid
artery (CCA) as well as ICA/CCA peak systolic velocity and end diastolic
velocity ratios.
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Dr Waleed Khoja
Biography:
After finishing High school, Dr Waleed Khoja joined King Saud University
Medical College. He gained his bachelor degree in Medicine and Surgery in
1988. At the same year, he joined the Riyadh Armed Forces Hospital as a
resident in Neurology Division.
In 1992, he was the first candidate to join Neurology Training Fellow Ship
Program held by the Medical College of King Saud University. He is the first
Neurologist who gained a Neurology fellowship degree from Saudi Arabia.
In 1997, he went to Germany, where he received extensive training in
Neurointensive care management. This took place in the Neurology Department,
University Hospital of Heidelberg. This training was under the direct
supervision of Professor Dr. med. Werner Hacke, a well recognized figure for
acute stroke therapy in the world.
Dr. Khoja has great interest in hyper acute therapy for all types of stroke
and good experience in management of brain edema. He, also, has vast
experience in Transcranial Doppler and duplex. He is currently in charge of
stroke services in the Division.
Recently, he was elected chairman of the Saudi Advisory
Group Against Stroke.
Lecture:
Transcranial sonographic applications (10:10 19:30 AM)
Abstract:
Simply, Transcranial Doppler (TCD) is a non invasive pulse wave
ultrasonography of the intracranial blood circulation and it is one of the
most rapidly growing sciences in neurosonology over the last decade. This tool
of investigation was introduced, as a full service, in the Department of
Neurosciences of Riyadh Armed Forces Hospital in 1993, being the first of its
kind in the Kingdom of Saudi Arabia. The technique is very simple and has a
high index of sensitivity and specifity.
TCD is used to assess blood flow velocity in the major basal intracranial
arteries on a real time, beat-to-beat basis. Blood flow velocity is calculated
and used to make determinations about intracranial hemodynamics. Additional
diagnostic criteria, such as flow direction, change or absence of signal,
differences in velocity values on left and right sides, waveform shape,
vasomotor reactivity, high intensity transient signal detection and others,
are also used in interpretation. Actually, TCD is your stethoscope to the
brain.
TCD technology added a lot of informations in understanding disease process
affecting the intracranial vessels. It is widely used in assessing and
following extra and intracranial vessels in a wide range of diseases,
including stroke, subarachnoid hemorrhage, internal carotid artery stenosis,
Moyamoya disease, sickle cell disease, mitochondrial cytopathies,
arteriovenous malformations and many others. Also, the relatively new
technique of color coated transcranial duplex made it possible to visualize
the intracranial vessels and brain midline structures with a reliable index of
accuracy and opened a wide door for new future research.
Lecture: By DWL
TCD and vasomotor reactivity (10:30-10:50 AM)
Abstract:
This method is done to assess the cerebrovascular (vasomotor) reserve in
patients with high risk for stroke. These include: Asymptomatic critical
carotid stenosis, MELAS and other mitochondrial cytopathies,
Arteriovenous malformations and Migraine.
It is done by continues monitoring of target vessel(s) at best depth
resolution by a 2 MHz TCD probe fixed with a band applied around the head;
unilaterally or bilaterally; according to nature of study. A capnometer is
connected to measure end-expiratory CO2 concentration continuously to assure
Hypercapnia. Patient should be relaxed and breathing normally before starting
the test. A steady state of mean blood velocity (Vmean) and CO2 concentration
should be achieved for 4 minutes prior to start of test. Then 1g of
acetazolamide is injected through an intravenous route 10 minutes after
injection, Vmean is measured again. The vasomotor reactivity is calculated
using the following formula:
a- % change in Vmean =
100X
(V1-V2)/V1
b- Absolute Vmean increase = V1-V2
V1 is the Vmean 10
minutes after acetazolamide injection
V2 is the Vmean at rest
Alternatively, test can be done with patient holding breath
as long as possible, where by a rise in blood C02 is reached.
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