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New insight in the use of ultrasonography in clinical neurology

Published in: Health & Medicine
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  2. 2. AGENDA  The advantages of medical ultrasound  Neurovascular ultrasound.  Uses of ultrasound in movement disorder  Uses of ultrasound in Peripheral nervous system  Skeletal muscle ultrasound
  3. 3. THE ADVANTAGES OF MEDICAL ULTRASOUND  Excellent safety  very high temporal and high spatial resolution  real-time evaluation  low cost  The ability to perform examinations at the bedside
  5. 5.  Vascular ultrasound was the first modality adopted in clinical neurology for the evaluation of extra cranial (1970s) and intracranial (1980s) vasculature
  6. 6. ALL CAROTID ARTERY EXAMINATIONS SHOULD BE PERFORMED WITH: • Gray-scale US • Color Doppler • Duplex ultrasonography • Power Doppler • Spectral Doppler
  7. 7. •Grayscale ultrasound to visualize the structure or architecture of the body part. No motion or blood flow is assessed.
  8. 8. •Color Doppler visualize the flow or movement of a structure, typically used to image blood within an artery. Blood flow velocities increase through a region of narrowing, like a finger pressing up against the end of a running garden hose. Increased velocities indicate a region of narrowing or resistance
  9. 9. • Duplex ultrasonography is a form of medical ultrasonography that incorporates the two elements (gray-scale doppler and color-doppler): • Power Doppler provide greater detail of blood flow, especially in vessels that are located inside organs. Power Doppler is more sensitive than color Doppler for the detection and demonstration of blood flow, but provides no information about the direction of flow
  10. 10. •Spectral Doppler is a method of graphically displaying the velocity of blood flow through the analysis of frequency and phase shift of the reflected ultrasound
  11. 11.  The extracranial internal carotid, common carotid, external carotid, and vertebral arteries can be assessed by cervical duplex.  while the middle cerebral, anterior cerebral, posterior cerebral, ophthalmic, intracranial vertebral, and basilar arteries can be investigated by transcranial Doppler or transcranial color-coded duplex sonography
  13. 13. 1-INFORMATION ABOUT PLAQUE COMPOSITION AND SURFACE  Cervical duplex ultrasonography can directly visualize atherosclerotic plaque composition that can be classified based on its echogenicity.  Uniformly hyperechoic carotid plaques are mainly composed of fibrotic tissue needed for plaque stability.  In contrast, heterogeneous (and predominantly hypoechoic) plaques consisting of matrix deposition, cholesterol accumulation, necrosis, calcification, and intraplaque hemorrhage are considered unstable, being the source of artery-to-artery embolic strokes
  14. 14. 2- DIAGNOSIS OF THE DEGREE OF CAROTID ARTERY STENOSIS  For grading the percentage of stenosis in extracranial carotid artery steno-occlusive disease using Peak systolic velocity, end-diastolic velocity, and the systolic internal carotid artery (ICA)/common carotid artery (CCA) velocity.
  15. 15. ICA Stenosis Range Peak Systolic Velocity (cm/s) End-Diastolic Velocity (cm/s) Peak Systolic Velocity ICA/ CCA Ratio Plaque Normal <125 <40 <2 Non 0-49% <125 <40 <2 <50% diameter reduction 50-69% 125-230 40-100 2-4 >50% diameter reduction 70-99% >230 >100 >4 >50% diameter reduction Near occlusion High/low or undetectable variable variable Significant, detectable lumen Occlusion Undetectable NA NA Significant, no detectable
  16. 16. OCCLUSION OF ICA  Retrograde flow in stump of ICA  Absence of flow in ICA beyond ICA ECA CCA
  17. 17. 3- SUBCLAVIAN STEAL PHENOMENON  refers to steno-occlusive disease of the proximal subclavian artery with retrograde flow in ipsilateral vertebral artery
  18. 18. VERTEBRAL TO SUBCLAVIAN STEAL Presteal Incomplete steal Complete steal Compared to bunny in profile
  19. 19. 4- DIAGNOSIS OF THE DEGREE OF VERTEBRAL ARTERY STENOSIS  There are no widely accepted duplex criteria for the diagnosis of vertebral artery stenosis. Some have used a peak systolic velocity of >100 cm/sec to diagnose a stenosis >50%. Bi-derectional flow could mean a high grade stenosis  A problem with ultrasound for the vertebral arteries is that the stenosis is often at the origin and this cannot be seen in many cases
  20. 20. 5- ULTRASONOGRAPHY MAY ASSIST IN THE DIAGNOSIS OF CAROTID OR VERTEBRAL ARTERY DISSECTION.  Cervical duplex ultrasonography may detect reversed systolic blood flow at the origin of the vessel and absent or minimal diastolic blood flow that concurs with high- resistance bidirectional Doppler signal.  In B-mode imaging, a tapered lumen with a characteristic string sign appearance may be shown, as well as a floating intimal flap. The true lumen can be compressed by the false lumen thrombus, and subsequently a low- velocity Doppler waveform can be recorded
  21. 21. 6- TAKAYASU AND TEMPORAL ARTERITIS  Takayasu arteritis presents with smooth homogenous concentric thickening of the arterial wall on B-mode imaging in proximal cervical vessels  In contrast to atherosclerotic disease, patients with Takayasu arteritis have an affected CCA with sparing of the ICA and external carotid artery.
  22. 22.  Giant cell arteritis An examination of the superficial temporal artery with high-frequency 12-MHz to 15-MHz B-mode transducers can detect hypoechoic circumferential thickening (the halo sign).The halo sign is moderately sensitive (68%) but highly specific (91%) when present at the superficial temporal artery and can also be used to guide biopsy as well as monitor treatment
  23. 23. 7- FIBROMUSCULAR DYSPLASIA String of beads pattern ICA
  25. 25. 1- Fast detection and localization of occlusion/stenosis
  26. 26.  2- Mapping of the collateral circulation
  27. 27.  3- Transcranial Doppler assesses recanalization and potential reocclusion in real time in patients with acute ischemic stroke treated with systemic or intraarterial reperfusion therapies
  28. 28.  4- Cerebral Arteriovenous Malformations  TCD is highly sensitive for large and medium-sized AVMs;  in acute cerebral hemorrhage TCD may help to differentiate AVM from non-AVM bleeds
  29. 29.  5- Cerebral Venous Thrombosis  ultrasonographic techniques are not sensitive enough to exclude cerebral venous thrombosis, but they may complement other imaging techniques. In the follow-up, sonographic findings are related to the functional outcome.
  30. 30.  6-The transcranial Doppler bubble test is more sensitive than transthoracic echocardiography (with or without contrast injection) in detection of a right-to-left shunt through a patent foramen ovale.  8-Transcranial Doppler stratifies the risk of patients with sickle cell anemia and those in need of blood transfusions for primary stroke prevention. Those who meet transcranial Doppler criteria for blood transfusions should stay on transfusions since these children remain at high risk of stroke if transfusions are discontinued
  31. 31.  8-Potential augmentation of clot lysis and clinical recovery (sonothrombolysis).  9- One of the first applications of TCD in clinical use has been the identification of cerebral vasospasm after subarachnoid hemorrhage (SAH). Blood extravasation has a toxic effect on brain arteries and leads to lumen narrowing that, when severe enough, can lead to ischemic lesions. TCD can estimate the severity of vasospasm by detecting increased blood velocities in areas of vasospasm.  10- Transcranial doppler sonography diagnostic value for the cerebral flow velocity changes in the interictal phase of classic migraine
  32. 32.  11- Brain death is a clinical diagnosis that can be supported by transcranial Doppler, given the ability of transcranial Doppler to detect cerebral circulatory arrest
  34. 34. AGENDA  The advantages of medical ultrasound  Neurovascular ultrasound.  Uses of ultrasound in movement disorder  Uses of ultrasound in Peripheral nervous system  Skeletal muscle ultrasound
  36. 36. MOVEMENT DISORDERS  The midbrain appears hypoechoic in transcranial sonography, surrounded by the hyperechoic basal cisterns, while the substantia nigra appears as a thin hyperechoic strip with total surface not exceeding 0.20 cm2 in normal subjects.  Increased substantia nigra hyperechogenicity can be detected with transcranial parenchymal sonography in approximately 90% of patients with idiopathic Parkinson disease.  Substantia nigra hyperechogenicity may serve as a preclinical marker of idiopathic parkinsonism.
  37. 37. Condition Substantia Nigra Hyperechog- enicity Lentiform Nucleus Hyperechoge- nicity Caudate Nucleus Hyperecho- genicity Increase of Third Ventricular Diameter Increase of Lateral Ventricular Diameter Healthy individual> 60 years old Rare Rare Rare Very rare Rare Idiopathic Parkinson disease Almost always Rare Often Never observed Very rare Multiple system atrophy Very rare Almost always Often Never observed Very rare Progressi- ve supranucl- ear palsy Rare Almost always Almost always Almost always Often
  38. 38. Condition Substantia Nigra Hyperechog- enicity Lentiform Nucleus Hyperechoge- nicity Caudate Nucleus Hyperecho- genicity Increase of Third Ventricular Diameter Increase of Lateral Ventricular Diameter Corticobasal degeneration Almost always Almost always Almost always Never observed Rare Dementia with Lewy bodies Almost always Rare Almost always Never observed Often
  40. 40. PERIPHERAL NERVOUS SYSTEM  Ultrasonography of a peripheral nerve examines five parameters: (1) cross-sectional area at certain sites of clinical interest (2) variability of the cross-sectional area along its course (3) echogenicity (4) vascularity (5) mobility
  41. 41.  Normal peripheral nerves have a tubular form, with alternating hypoechoic (nerve fibers) and hyperechoic (perineurium) zones that give the impression of a honeycomb pattern
  42. 42. ENTRAPMENT NEUROPATHIES Carpal tunnel syndrome. 1. Enlarged CSA of the median nerve proximal to the edge of the flexor retinaculum (normal value less than 0.11 cm2) 2. Increased wrist to forearm swelling ratio 3. Hypoechogenicity and disturbed fascicular echo structure 4. Reduced slippage of the nerve after finger flexion 5. Increased vascularity
  43. 43. Cubital tunnel syndrome CSA > 0.09 cm2 Elbow to upper arm ratio >1.4 Reduced echogenicity Increased echogenicity of epineurium Radial nerve compression CSA > 0.06 cm2 Reduced echogenicity Fibular nerve compression CSA > 0.12 cm2 Reduced echogenicity Popliteal fossa to fibular head ratio > 1.4 Cervical radiculopathy Side-to-side difference ratio >1.5
  44. 44. INFLAMMATORY POLYNEUROPATHIES Chronic inflammatory demyelinating polyradiculoneuropathy Brachial plexus hypertrophy and multifocal peripheral nerve hypertrophy can be seen differentiating this condition From AIDP using Bochum ultrasound score Multifocal motor neuropathy multifocal pattern of nerve enlargement at sites with or without clinical or electrophysiologic abnormalities differentiating this condition from amyotrophic lateral sclerosis
  45. 45. Systemic vasculitis Diffuse thickening of peripheral nerves, primarily of the lower limbs, and reduction of nerve diameter after corticosteroid therapy have been described using Ultrasound
  47. 47. SKELETAL MUSCLE ULTRASOUND  Neuromuscular disorders can lead to increased muscle echo intensity, i.e. a muscle becomes whiter in appearance.  it reliable to assess muscle thickness and objectify muscle atrophy.  it is also very suitable to visualize muscle movements as fibrillations.  It can additionally be used to select the optimal site for muscle biopsy
  48. 48. INTERVENTIONAL ULTRASOUND  Ultrasound can be used to guide steroid injection near the median nerve for the treatment of carpal tunnel syndrome.  Under ultrasound guidance, botulinum toxin can be injected into muscles for spasticity and dystonia or into the salivary glands for sialorrhea.  The most common situation in which ultrasound is used to guide intervention is for regional anesthesia.  Other interventional procedures in which ultrasound can by used include guidance of muscle and nerve biopsy also in determination of optimal lumbar puncture site
  49. 49. ULTRASOUND AS A COMPLEMENT TO ELECTRODIAGNOSTIC STUDIES  Ultrasound can improve nerve conduction study techniques by visualizing nerve pathways involved in surface stimulation and recording.  The accuracy of needle placement in cadavers for diagnostic electromyography is 96% with ultrasound guidance, whereas it is only 50% to 83% (depending on operator experience) without ultrasound.  Ultrasound, including color Doppler detection of vascular structures, can improve the safety of diagnostic electromyography (EMG) in anticoagulated patients, and it allows for continued monitoring after the procedure for hematoma development.
  50. 50.  Diaphragmatic EMG is a relatively safe procedure, but there is a risk of pneumothorax. Ultrasound can make this procedure safer by allowing direct visualization of diaphragm and lung movement with respiration, which permits accurate estimates of optimal insertion points and necessary needle depth or real- time guidance of the EMG needle into the diaphragm