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The First Saudi Transcranial Doppler (TCD) Workshop

9 September, 2002, Riyadh, Armed Forces Hospital


Speakers Biographies and Abstracts

  • 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.


  • 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.


  • 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.


  • 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.


  • 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.


  • 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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