TCD

Pulsed wave Doppler measurement of blood flow velocity.

2 MHz transducers direct ultrasound wave at the basal blood vessels.

Image reveals speed and direction of flow.

Use bone windows to insonate:

Transtemporal (MCA, ACA, PCA, ACoA, PCoA)

Suboccipital (vertebrals, basilar)

Transorbital (Ophthalmic, Carotid siphon)

Submandibular (ICA)

Locating arteries:

Depth of the volume.

Angle of the transducer.

Direction of the blood flow relative to the transducer.

Spatial relationship of one doppler signal to another.

Traceability of an artery.

Transducer remains on window, constant angle for each vessel

Constant interface of signal intensity

Arterial identification:

Adjust angle to obtain proper artery

Adjust depth to insonate from distal to proximal (depth measured based on head size)

TCD Spectral Waveforms determine velocity at the artery:

1.Mean velocity

2. Pulsatility Index:

Peak systolic-end diastolic

-----------------------------------------

mean velocity

After calculation:

Compare velocity to norms to determine stenosis/spasm.

Compare spectral waveforms from anterior and posterior circulations, left and right.

Note any disease of extracranial carotid and vertebral arteries which may impact values.

Note pulsatility index.

Consider physiologic factors.

Artery Mean velocity (cm/sec)

MCA 62 ± 12

ACA 50 ± 11

T-ICA 39 ± 9

PCA 30 ± 10

Ophth 21 ± 5

Siphon 47 ±14

Vertebral 38 ± 10

Basilar 41 ± 10

ICA-sub 37 ± 9

Physiologic Factors

• AGE : lower velocities with increasing age
• H&H : hematocrit less than 30 increases velocity
• Hypoglycemia: increases bloodflow to increase delivery of glucose to brain, only a factor with glucose below 40
• Hyperventilation: decreases velocity
• Hypoventilation: increases velocity
• Gender: Females have 3-5% increase in MCA velocity
• Fever: velocity increases by 10% for every degree of increase in temperature
• Heart rate: sweep speed has to be accomodated for bradycardia or tachycardia.)

Normal TCD Criteria:

1. Normal Flow direction

2. Velocity/pulsatility symmetry (Left:Right difference is less than 30%)

3. Velocity hierarchy is respected.

4. Pulsatility Index is 0.6-1.1 in normotensive patients. (can be>1.2 in patients with hypertension)

5. Note any microemboli, shunt (if applicable)

6. Vasoreactivity response

Microemboli detection: assessment of stroke risk or antiplatelet therapy.

Emboli detection device

1. Doppler microembolic signals are transient; generally lasting less than 300 msec.

Embolic signal duration depends on the time of passage through the Doppler sample volume, random throughout cardiac cycle..

2. Microembolic signal amplitude is usually at least three decibels higher than that of the background blood flow signal.

3. Microembolic signals are unidirectional within the Doppler velocity spectrum

4. A microembolic signal audibly sounds like a snap, chirp, or moan

BUBBLE STUDY

Detects a right to left shunt via PFO or a pulmonary AVM.

Protocol

1. Patient in the supine position.

2. Place an IV line in the antecubital vein using a 21-gauge needle on a butterfly with a plastic tube extension to a 3-way stopcock.

3. Monitor the bilateral middle cerebral arteries (MCA) using a headframe and two 2 MHz TCD probes fixated on the bilateral transtemporal window.

( MCA flow is toward the probe and monitored at a depth of 50 to 55 mm.

4. Record a five minute baseline.

5. Attach an empty 10mL syringe to the 3-way stopcock.

6. Fill a second 1OmL syringe with 9 mL of bacteriostatic saline and 1 mL of air. Place the second syringe on the 3-way stopcock.

7. Agitate the saline between the two syringes and when it becomes a frothy white color inject the saline as a bolus.

8. As soon as the bolus is finished, watch and listen for microembolic signals to pass through the MCA waveforms.

9. Wait another five minutes and repeat the protocol, this time having the patient perform a Valsalva maneuver just at the bolus is finished. The patient should hold the maneuver for ten seconds.

Bubble Study Interpretation

As the bolus is finished, listen for microembolic signals. Any amount of bubbles seen and heard within either MCA is suggestive of a right to left shunt. .

The grading scale is as follows:

Grade I 1 to 10 microembolic signals

Grade II 11 to 30 microembolic signals

Grade III 31 to 100 microembolic signals

Grade IV 101 to 300 microembolic signals

Grade V greater than 300 microembolic signals, many uncountable

Vasoreactivity study: Assessment of Collateralization

Vasomotor reserve is the ability of the cerebral vessels to maintain adequate blood perfusion in the brain regardless of changes in pressure gradients, body position, or blood pressure. This perfusion is maintained through vessel dilation and constriction. If this perfusion mechanism is abnormal, the patient has an elevated risk for stroke. This can be tested by breath holding induced vasodilation. Alternatively it can be tested by CO2 challenge.

The breath-holding maneuver (TCD breath-holding test):

1. Normal breathing of room air for approximately 4 minutes.

2. Patients hold their breath after a normal inspiration.

3. During the maneuver the MCA mean blood velocity is recorded continuously.

4. The mean blood velocity at the TCD display immediately after the end of the breath-holding period is registered as the maximal increase of the MCA mean blood velocity (while breath-holding).

5. The time of breath-holding is registered.

The breath-holding index (BHI) is calculated:

[Vbh-Vr/Vr] · 100 · s-1

Breath holding index : % increase in MCA mean velocity by breath-holding/ divided by seconds of breath-holding

( Vbh is MCA mean blood velocity at the end of breath-holding, Vr the MCA mean blood velocity at rest, and s-1 per second of breath-holding)

Transcranial Color Doppler

• 2-D, gray-scale real time imaging with pulsed-wave doppler and color coded display of velocity.
• 1-3.5 MHz transducer.
• Able to outline intraparenchymal structures, place doppler on specific site of artery, visualize basal arteries in color.

More expensive than TCD.

Same disadvantages: bone window, limited accuracy.

Flow velocities are 10-30% higher than "blind" TCD, different reference values.

Acute Stroke

Removes "blind" element of thrombolysis by detecting embolic occlusion not seen on early conventional angiography.

Used to montior effects of thrombolytic agents and adjust dosage. Follow-up studies assess recanalization or recurrent occlusion.

*limitation in embolic occlusions of distal branches, beyond reach of TCD. TCCD is better in this situation.

Intracranial occlusion

TCD less accurate in detection occlusions than stenosis.

TCCD is more accurate than TCD: MCA occlusion detection 70-100% sensitivity and specificity.

Not useful for branch occlusions.

Collateralization/Vasoreactivity (Breath Holding Index of TCD)

Patients with carotid artery disease or intracranial vessel disease have an increased risk for stroke, transient ischemic attack, and ischemic eye disease due to inadequate cerebral blood perfusion.

Patients with a previous history of stroke or head injuries can also benefit from a vasomotor reserve evaluation.

It is also seen in hypertensive patients even without extracranial stenosis and is a risk marker for lacunar infarcts.

Vasomotor reserve testing is performed in order to determine if the patient's blood vessels are able to dilate and maintain sufficient blood perfusion in response to a decrease in blood pressure.

If the vessels are maximally dilated and there is inadequate vasomotor reserve to supply blood, the patient is at risk for ischemic stroke. Patients with a poor vasomotor reserve may require surgical intervention such as an endarterectomy or extracranialintracranial bypass surgery

HEAD ROTATION

Rotational vertebrobasilar ischemia (RVBI) occurs with changes of head and neck position.

Symptoms of RVBI are usually brief and occur every time the patient turns into position.

Symptoms include dizziness, vertigo, vision changes, and syncope or near-syncope.

The most common cause of RVBI is compression of one or both of the vertebral arteries.

Vertebral spondylarthrosis in the cervical segment can cause compression of the vertebral artery (VA). This, along with having an anomaly of the second vertebral artery (hypoplasia or VA ending in the posterior inferior cerebellar artery instead of joining with the contralateral VA to form the basilar artery) may cause loss of blood flow to the posterior aspect of the brain (Sturzenegger et al. 1994).

B. TRANSCRANIAL DOPPLER (TCD) (93886, 93888, 93890, 93892, 93893)

The accuracy of TCD examinations depends on the knowledge, skill and experience of the technologist and interpreter. Consequently, the providers of TCD studies must be capable of demonstrating documented training and experience and maintain documentation for post-payment audit. An example of acceptable training and experience would be a physician and/or registered vascular technologist with documentation of attendance at a formal TCD training program that includes hands on experience and results in a certificate of proficiency, and with a minimum experience of 100 patient TCD examinations.

1. TCD is an allowed procedure and is of established value in:

a. Detection and evaluation of the hemodynamic effects of severe stenosis or occlusion of the extracranial (greater than or equal to 60 percent) and major basal intracranial arteries (greater than or equal to 50 percent, diameter reduction).

b. Detection and serial evaluation of cerebral vasospasm complicating subarachnoid hemorrhage.

c. Evaluation of invasive therapeutic interventions for cerebral arteriovenous malformations.

d. Intraoperative and perioperative monitoring of intracranial flow velocity and hemodynamic patterns during carotid artery intervention. This is primarily a Medicare Part A procedure but the professional component could be reimbursed, given it is provided during the operative procedure by a physician that is not a member of the operating team.

e. Evaluation of cerebral emobilization.

f. Detection and evaluation of intracranial vascolopathy in children with sickle cell disease (two to four per year allowed).

2. Examples of non-acceptable indications include:

a. Evaluation of brain tumors.

b. Assessment of familial and degenerative diseases of the cerebrum, brainstem, cerebellum, basal ganglia and motor neurons.

c. Evaluation of infectious and inflammatory conditions.

d. Psychiatric disorders.

e. Epilepsy.

3. The following applications are in the research phase and are considered investigational:

a. Assessing patients with migraine.

b. Monitoring during cardiopulmonary bypass.

c. Monitoring during investigational interventions.

d. Evaluation of patients with dilated vasculopathies such as fusiform aneurysms.

e. Assessing autoregulation, physiologic, and pharmacological responses of cerebral arteries.

f. According memorandum B-01-28 Physician Supervision of Diagnostic Tests

g. 93886 & TC, 93880 & TC are covered under level 1 supervision.

h. Level 1 =Procedure must be performed under the general supervision of a physician

i. General supervision is defined as overall direction and control but need not be presence during the performance of the test.

AAN Guidelines

Summary of findings

Subarachnoid Hemorrhage (SAH):

Summary of findings

Cerebral Thrombolysis (continued)

INDICATION

SENSITIVITY (%)

SPECIFICITY (%)

Monitoring in the Neurology/ Neurosurgery Intensive Care Unit

REFERENCE STANDARD

Summary of findings

Cerebral Thrombolysis

Summary of findings

Subarachnoid Hemorrhage (SAH) (continued)

Recommendation: TCD is probably useful for monitoring thrombolysis of acute MCA occlusions (Type B, Class II-III evidence).

Present data are insufficient to either define the optimal frequency of TCD monitoring for clot dissolution and enhanced recanalization or to influence therapy (Type U).

Vasospasm after Spontaneous Subarachnoid Hemorrhage

Conventional angiography

REFERENCE STANDARD

INDICATION

SPECIFICITY (%)

SENSITIVITY (%)

INDICATION

Intracranial ICA

SENSITIVITY (%)

25-30

83-91

SPECIFICITY (%)

BA

Conventional angiography, magnetic resonance angiography, clinical outcome

REFERENCE STANDARD

77-100

Summary of findings

Coronary Artery Bypass Graft (CABG) Surgery

Summary of findings

Traumatic SAH (tSAH)

MCA

PCA

42-79

39-94

Cerebral Thrombolysis

70-100

48-60

INDICATION

ACA

78-87

13-71

65-100

SENSITIVITY (%)

REFERENCE STANDARD

VA

100

SPECIFICITY (%)

44-100

SPECIFICITY (%)

50

82-88

Vasospasm after Traumatic Subarachnoid Hemorrhage

Complete Occlusion

REFERENCE STANDARD

SENSITIVITY (%)

Recommendations: TCD is useful for the detection and monitoring of angiographic VSP in the basal segments of the intracranial arteries, especially the MCA and BA, following sSAH (Type A, Class I-II evidence).

More data are needed to show if TCD affects clinical outcomes in this setting (Type U).

76

INDICATION

100

Conventional angiography

Partial Occlusion

93

91

Recanalization

Coronary Artery Bypass Graft (CABG) Surgery

Summary of findings

Carotid Endarterectomy (CEA)

Summary of findings

Increased Intracranial Pressure (ICP) and Cerebral Circulatory Arrest

REFERENCE STANDARD

Recommendation: TCD is possibly effective in documenting changes in flow velocities and CO2 reactivity in patients who undergo CABG (Type C, Class III evidence).

TCD is probably useful for the detection and monitoring of cerebral microemboli in patients undergoing CABG (Type B, Class II-III evidence). Data are presently insufficient regarding the clinical utility of this information (Type U).

Recommendation: TCD is probably useful for the detection of VSP and cerebral hemodynamic impairment following tSAH (Type B, Class I-III evidence).

Data on sensitivity, specificity and predictive value of TCD for VSP after tSAH are needed.

Data are insufficient regarding how use of TCD affects clinical outcomes after tSAH (Type U).

SPECIFICITY (%)

INDICATION

EEG, magnetic resonance imaging, clinical outcomes

SENSITIVITY (%)

INDICATION

Cerebral Circulatory Arrest and Brain Death

SPECIFICITY (%)

  91-100

REFERENCE STANDARD

97-100

Carotid Endarterectomy (CEA):

Conventional angiography, EEG, clinical outcome

Recommendation: TCD is a useful adjunct test for the evaluation of cerebral circulatory arrest associated with brain death (Type A, Class II evidence).

Recommendation: CEA monitoring with TCD can provide important feedback pertaining to hemodynamic and embolic events during and after surgery that may help the surgeon take appropriate measures at all stages of the operation to reduce the risk of perioperative stroke.

TCD monitoring is probably useful during and after CEA in circumstances where monitoring is felt to be necessary (Type B, Class II-III evidence).

Transcranial Color-Coded Sonography (TCCS) or Imaging TCD

Perioperative and Periprocedural Monitoring

Summary of findings

Detection of Cerebral Microemboli

Transcranial Color-Coded Sonography (TCCS)

REFERENCE STANDARD

INDICATION

SPECIFICITY (%)

SENSITIVITY (%)

Experimental model, pathology, magnetic resonance imaging, neuropsychological tests

SENSITIVITY (%)

SPECIFICITY (%)

Transcranial Color-Coded Sonography (TCCS), with/without contrast enhancement

INDICATION

REFERENCE STANDARD

Cerebral Microembolization

Conventional angiography, pathology

Recommendation: TCD is probably useful to detect cerebral microembolic signals in a wide variety of cardiovascular/ cerebrovascular disorders/procedures (Type B, Class II-IV evidence).

However, data at present do not support the use of TCD for diagnosis or for monitoring response to antithrombotic therapy in ischemic cerebrovascular disease in these settings(Type U).

Summary of findings

Ischemic Cerebrovascular Disease

INDICATION

ACoA Collateral Flow

Summary of findings

Vasomotor Reactivity (VMR) Testing

(continued)

SENSITIVITY (%)

100

SPECIFICITY (%)

PCoA Collateral Flow

100

85

REFERENCE STANDARD

Recommendation: TCD vasomotor reactivity testing is considered probably useful for

the detection of impaired cerebral hemodynamics in patients with asymptomatic severe (>70%) stenosis of the extracranial ICA

patients with symptomatic or asymptomatic extracranial ICA occlusion and patients with cerebral small artery disease (Type B, Class II-III evidence).

How the results from these techniques should be used to influence therapy and affect patient outcomes remains to be determined (Type U).

98

Summary of findings

Ischemic Cerebrovascular Disease

(Continued)

INDICATION

REFERENCE STANDARD

Summary of findings

Vasomotor Reactivity (VMR) Testing

Conventional angiography, clinical outcomes

SENSITIVITY (%)

SPECIFICITY (%)

Intracranial Steno-Occlusive Lesions

Any

SPECIFICITY (%)

SENSITIVITY (%)

INDICATION

REFERENCE STANDARD

Up to 100

Up to 83

Vasomotor Reactivity (VMR) Testing

/= 70% extracranial

ICA stenosis / occlusion

REFERENCE STANDARD

Summary of findings

Ischemic Cerebrovascular Disease

(Continued)

INDICATION

Summary of findings

Extracranial ICA Stenosis

Conventional angiography

/= 50% Stenosis

SPECIFICITY (%)

SENSITIVITY (%)

MCA

ACA

SENSITIVITY (%)

60-100

VA

SPECIFICITY (%)

BA

100

42-100

PCA

INDICATION

3-78

100

REFERENCE STANDARD

100

49-95

Extracranial ICA Stenosis:

100

Single TCD variable

89

100

Recommendation:TCD is possibly useful for the evaluation of severe extracranial ICA stenosis or occlusion (Type C, Class II-III evidence).

100

TCD Battery

100

TCD Battery & Carotid Duplex

REFERENCE STANDARD

Summary of findings

Ischemic Cerebrovascular Disease

(Continued)

Summary of findings

Acute cerebral infarction

SPECIFICITY (%)

90-98

Recommendation: (CE)-TCCS is probably useful in the evaluation and monitoring of patients with ischemic cerebrovascular disease (Type B, Class II-IV evidence).

SENSITIVITY (%)

85-95

INDICATION

Recommendation: TCD is probably useful for the evaluation of patients with suspected intracranial steno-occlusive disease, particularly in the ICA siphon and MCA (Type B, Class II evidence).

The relative value of TCD compared with MRA or CTA remains to be determined (Type U).

Data are insufficient to give a recommendation regarding replacing conventional angiography with TCD (Type U).

Acute cerebral infarction

INDICATION

REFERENCE STANDARD

Parenchymal Hypoechogenicity in MCA Distribution

Summary of findings

Hemorrhagic Cerebrovascular Disease

SENSITIVITY (%)

SPECIFICITY (%)

Summary of findings

Intracranial Steno-Occlusive Disease (Continued )

69

90-98

SPECIFICITY (%)

96

SENSITIVITY (%)

83

85-95

REFERENCE STANDARD

55-81

INDICATION

Recommendation: Data are insufficient to establish TCD criteria for greater than 50% stenosis or for progression of stenosis in intracranial arteries (Type U).

Recommendation: (CE-) TCCS is probably useful in the evaluation and monitoring of patients with aneurysmal SAH or intracranial ICA/MCA VSP following SAH (Type B, Class II-III evidence).

Data are insufficient regarding the use of TCCS to replace CT for diagnosis of ICH (Type U).

Computed tomographic scan

MCA

ICA, VA, BA

REFERENCE STANDARD

INDICATION

Summary of findings

Vasospasm after Spontaneous Subarachnoid Hemorrhage

Conventional angiography

Summary of findings

Intracranial Steno-Occlusive Disease

Vasospasm after Spontaneous Subarachnoid Hemorrhage

SPECIFICITY (%)

Intracranial ICA

SENSITIVITY (%)

MCA

ACA

69

90-95

SENSITIVITY (%)

SPECIFICITY (%)

80-96

100

83

70-90

100

INDICATION

71

REFERENCE STANDARD

50-80

97

Intracranial Steno-Occlusive Disease:

Conventional angiography

93

Anterior Circulation

85

Posterior Circulation

Occlusion

INDICATION

Intracerebral Hemorrhage

Summary of findings

Intracerebral Hemorrhage

SENSITIVITY (%)

94

REFERENCE STANDARD

SPECIFICITY (%)

Transesophageal echocardiography

95

Summary of findings

Right to Left Cardiac Shunts

Recommendation:There are insufficient data to support the routine clinical use of TCD/TCCS for other indications including: migraine, cerebral venous thrombosis, monitoring during cerebral angiography, evaluation of arteriovenous malformations, evaluation of cerebral autoregulation in other settings (Type U recommendation).

REFERENCE STANDARD

SPECIFICITY (%)

95

Computed tomographic scan

SENSITIVITY (%)

70-100

Recommendation: Contrast TCD is comparable to contrast TEE for detecting right to left shunts due to PFO (Type A, Class II evidence). TEE is superior than contrast TCD since it provides direct anatomic information regarding the site and nature of the shunt or presence of an ASA. While the number of microbubbles reaching the brain can be quantified by TCD, the therapeutic impact of this additional information is unknown (Type U).

INDICATION

Right to Left Cardiac Shunts

REFERENCE STANDARD

Conventional angiography

SPECIFICITY (%)

Summary of findings

Sickle Cell Disease

Summary of TCD recommendations

Settings in which TCD is able to provide information and in which its clinical utility is established

91

SENSITIVITY (%)

Screening of children aged 2-16 years with sickle cell disease for assessing stroke risk (Type A, Class I), although the optimal frequency of testing is unknown (Type U).

Detection and monitoring of angiographic vasospasm after spontaneous subarachnoid hemorrhage (Type A, Class I-II). More data are needed to show if its use affects clinical outcomes (Type U).

Recommendation: TCD screening of children with SCD between the ages of 2 and 16 years is effective for assessing stroke risk (Type A, Class I evidence), although the optimal frequency of testing is unknown (Type U).

86

INDICATION

Sickle Cell Disease

Recommendations for future research

Intracranial Steno-Occlusive Disease:

More data are needed to define the ability of TCD to detect >/= 50% stenosis of major basal intracranial arteries vs. MRA and CTA. Once MRA and CTA are validated, the determination of the relative value of each technique for specific vascular lesions which may influence patient management. The ability of TCD to predict outcome in vertebrobasilar distribution stroke, if any, requires study. The value of TCD in the prediction of hemorrhagic transformation of ischemic infarction needs confirmation in well designed studies of patients who do and do not receive anticoagulation or thrombolysis.

Extracranial ICA Stenosis:

The clinical utility of TCD’s ability to detect impaired cerebral hemodynamics distal to high grade extracranial ICA stenosis or occlusion and assist with stroke risk assessment needs confirmation and evaluation in randomized clinical trials. In patients with symptomatic ICA occlusion, it would be useful to directly compare TCD/vasomotor reactivity testing with PET to see if TCD would be valuable to select and serially monitor patients for extracranial to intracranial bypass surgery. In patients with asymptomatic high grade ICA stenosis, it would be useful to learn if TCD assessment of vasomotor reactivity or microembolic signal detection can improve selection of patients for CEA or angioplasty.

Conventional or Non-imaging TCD

Limitation of TCD:

examination of cerebral blood flow velocities in certain segments of large intracranial vessels

detects indirect effects (abnormal waveform characteristics) suggesting of proximal hemodynamic or distal obstructive lesions

more valuable in specific conditions

Introduction

Advantages of TCD:

non-invasive

can be performed at the bedside

easily repeated or used for continuous monitoring

is generally less expensive than other techniques

contrast agents are not used avoiding allergic reactions and decreasing risk to the patient

Introduction

TCD is a non-invasive ultrasonic technique measuring local blood flow velocity and direction in the proximal portions of large intracranial arteries.

TCD’s principal use is in the evaluation and management of patients with cerebrovascular disease.

AAN’s Recommendation levels

Level C:

Possibly useful/ predictive or not useful/ predictive for the given condition in the specified population. /=2 convincing and consistent Class III studies

Level U:

Data inadequate or conflicting. Given current knowledge, test/predictor unproven.

AAN’s Recommendation levels

Level A:

Established as useful/ predictive or not useful/ predictive for the given condition in the specified population. /= 1 convincing Class I or /=2 consistent, convincing Class II studies.

Level B:

Probably useful/ predictive or not useful/ predictive for the given condition in the specified populations. /= 1 convincing Class II or /=3 consistent Class III studies

AAN’s Class of evidence for determining the yield of established diagnostic and screening tests

Class III:

Evidence provided by retrospective study where persons with condition or controls are of narrow spectrum. Study measures predictive ability using independent gold standard to define cases. Risk factor measured in evaluation masked to outcome.

Class IV:

Any design where predictor is not applied in masked evaluation OR evidence by expert opinion, case series.

AAN’s Class of evidence for determining the yield of established diagnostic and screening tests

Class I:

Evidence provided by prospective study in broad spectrum of persons who may be at risk of outcome (target disease, work status). Study measures predictive ability using independent gold standard to define cases. Predictor is measured in evaluation masked to clinical presentation. Outcome is measured in evaluation masked to presence of predictor.

Class II:

Evidence provided by prospective study of narrow spectrum of persons who may be at risk for having the condition, retrospective study of broad spectrum of persons with condition compared to broad spectrum of controls. Study measures prognostic accuracy of risk factor using acceptable independent gold standard to define cases. Risk factor is measured in evaluation masked to the outcome.

Methods of evidence review

Sensitivity and specificity were operationally defined as excellent (>/= 90%), good (80-89%), fair (60-79%) and poor (<60%).

The clinical utility of a diagnostic test was operationally defined as the value of the test result to the clinician caring for the individual patient.

Panel summarized the clinical utility of TCD/TCCS and focus on the clinical indications for which conclusions can be drawn.

ASSESSMENT: TRANSCRANIAL DOPPLER ULTRASONOGRAPHY

Methods of evidence review

Panel reviewed summary statements and other articles, based upon selection of relevant publications cited in these new articles and additional MEDLINE search through June, 2003 using the AAN rating system,

Articles reviewed and cited contain a mixture of diagnostic, therapeutic or prognostic information used as the reference standard in individual studies.

Sensitivity and specificity reflect the ability of a diagnostic test to detect disease. Reviewed for TCD and TCCS.

Objective of the guideline

To review the use of transcranial Doppler ultrasonography (TCD) and transcranial color-coded sonography (TCCS) for diagnosis.

ICD-9 Codes

CPT codes

900.00-900.03 Injury to carotid artery

900.1 Injury to internal jugular vein

900.81-900.82 Injury to other specified blood vessels of head and neck

900.89 Injury to other blood vessels of head and neck

900.9 Injury to unspecified blood vessel of head and neck

901.1 Injury to innominate and subclavian arteries

958.4 Traumatic shock

996.1 Mechanical complication of other vascular device, implant, and graft 996.74 Other complication due to other vascular device, implant and graft

998.11-998.13 Hemorrhage or hematoma or seroma complicating a procedure

998.2 Accidental puncture or laceration during a procedure

998.31-998.32 Disruption of operation wound

998.4 Foreign body accidentally left during a procedure

998.6-998.7 Other complications of procedures,

NECV43.4 Blood vessel replaced by other means

V67.00 Follow-up examination, following unspecified surgery

V67.09 Follow-up examination, following other surgery  

93888©TCD, incomplete (bone window)

93886©TCD study

93890©TCD, vasoreactivity study

93892©TCD, emboli detect w/o inj

Medicare is establishing the following limited coverage for codes CPT/HCPCS codes 93886, 93888, 93890, 93892 and 93893:

Covered for:

348.8 Other conditions of brain (suspected brain death).

362.30-362.37 Retinal vascular occlusion

362.84 Retinal ischemia

368.10-368.12 Subjective visual disturbance

368.2 Diplopia

368.40-368.47 Visual field defects

430 Subarachnoid hemorrhage

431 Intracerebral hemorrhage

433.00-433.01 Occlusion and stenosis of basilar artery

433.10-433.11 Occlusion and stenosis of carotid artery

433.20-433.21 Occlusion and stenosis of vertebral artery

433.80-433.81 Occlusion and stenosis of other specified precerebral artery

433.90-433.91 Occlusion and stenosis of unspecified cerebral artery

434.00-434.01 Occlusion of cerebral arteries, thrombosis, with/without mention of cerebral infarction

434.10-434.11 Occlusion of cerebral arteries, embolism, with/without mention of cerebral infarction

434.90-434.91 Occlusion of cerebral arteries

435.0-435.3 Transient cerebral ischemia

435.8-435.9 Transient cerebral ischemia

436 Acute, but ill-defined cerebrovascular disease

Authors

Michael A. Sloan, MD, MS; Andrei V. Alexandrov, MD, RVT; Charles H. Tegeler, MD; Merrill P. Spencer, MD; Louis R. Caplan, MD; Edward Feldmann, MD; Lawrence R. Wechsler, MD; David W. Newell, MD; Camilo R. Gomez, MD; Viken L. Babikian, MD; David Lefkowitz, MD; Robert S. Goldman, MD; Carmel Armon, MD; Chung Y. Hsu, MD, PhD; and Douglas S. Goodin, MD

437.0-437.1 Other and ill-defined cerebrovascular disease

437.3-437.5 Other and ill-defined cerebrovascular disease

437.7 Transient global amnesia

437.9 Unspecified, cerebrovascular disease or lesion

442.81-442.82 Other aneurysm of other specified artery

444.9 Arterial embolism and thrombosis of unspecified artery Note: Use this code to report paradoxical cerebral embolism.

446.0-446.1 Polyarteritis nodosa and allied conditions

446.20-446.21 Hypersensitivity angiitis

446.29 Other specified hypersensitivity angiitis

447.0-447.2 Other disorders of arteries and arterioles

447.6 Arteritis unspecified

447.8-447.9 Other disorders of arteries and arterioles

780.2 Syncope and collapse Note: Report this code when symptomatology indicates a strong clinical suspicion of vertebrobasilar insufficiency.

781.2-781.5 Symptoms involving nervous and musculoskeletal system

782.0 Disturbance of skin sensation

784.3 Aphasia

784.5 Other speech disturbance

785.9 Other symptoms involving cardiovascular system Note: Use this code to report carotid bruit.

Transcranial Doppler (TCD) studies (93886, 93888, 93890, 93892 and 93893) are indicated for the following:

Detection of severe stenosis (>65 percent) in the major basal intracranial arteries.

Assessment of patterns and extent of collateral circulation in patients with known regions of severe stenosis or occlusion.

Intraoperative monitoring during carotid surgery.

Evaluation and follow-up of patients with vasoconstriction or spasm resulting from an illness, disease or injury, especially after subarachnoid hemorrhage.

Detection of arteriovenous (AV) malformations and studying their supply arteries and flow patterns.

An adjunct in the assessment of patients with suspected brain death.

2013 Medicare:

*93886 (TCD) 236.15

93888 (incomplete) 110.89

*93890 (vasoreactivity) 172.96

93892 (microemboli) 181.55

Aetna s/b 130% of 2009 MC

BCBS s/b 140% of their standard fees for each of the PPO and Par schedules,

References

Babikian, Wechsler, Higashida, Imaging Cerebrovascular Disease, 2003.

Yeo, L. Sharma, VK. Role of TCD Ultrasonography in Cerebrovascular Disease. 2009

Assessment:TCD. Report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology. Neurology 2004;62(9):1468

Akopov S, et al. Hemodynamic Studies in Early Ischemic Stroke. Stroke 2002:33:1274

Alexandrov AV, et al. CLOTBUST:Design of a Randomized Trial of Ultrasound Enhanced Thrombolysis for Acute Ischemic Stroke. J Neuroimaging. 2004: 14 (2) 108-12

Chimowitz MI, et al. Comparison of Warfarin and Aspirin for Symptomatic Intracranial Arterial Stenosis. N Eng J Med. 2005:352:1305-16

Komotar RJ, et al. Current Endovascular Treatment Options for Intracranial Carotid Artery Atherosclerosis. Neurosurg Focus 2005;18

Nichols FT, et al. Stroke Prevention in Sickle Cell Disease (STOP) Study Guidelines for Transcranial Doppler Testing. J Neuroimaging.2001; 11(4):354-62

Sauvageau E, et al. Recent Advances in Endoluminal Revascularization for Intracranial Atherosclerotic Disease. Neurol Res. 2005:27

Spence JD, et al. Absence of Microemboli on Transcranial Doppler Identifies Low-Risk Patients with Asymptomatic Carotid Stenosis. Stroke 2005; 36:2373-8

IAME. Carotid and Transcranial Doppler. September 2005.

Sciencedirect.com. Images of TCD

www.karger.com. Images of PI.

en.wikipedia.org. Images of Circle of Willis.

swedish.org. Microemboli detector.

circ.ahajournals.org. Microemboli.

Carefusion. Medicare Reimbursement by State.

Mcgs.bcbsfl.com Transcranial Doppler studies.

Report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology

Neurology 2004;62(9):1468

Summary of TCD recommendations

Settings in which TCD is able to provide information, but in which its clinical utility remains to be determined

Cerebral Thrombolysis: TCD is probably useful for monitoring thrombolysis of acute MCA occlusions (Type B, Class II-III). More data are needed to assess the frequency of monitoring for clot dissolution and enhanced recanalization and to influence therapy (Type U).

Cerebral Microembolism Detection: TCD monitoring is probably useful for the detection of cerebral microembolic signals in a variety of cardiovascular/ cerebrovascular disorders/procedures (Type B, Class II-IV). Data do not support the use of this TCD technique for diagnosis or monitoring response to antithrombotic therapy in ischemic cerebrovascular disease (Type U).

Carotid Endarterectomy: TCD monitoring is probably useful to detect hemodynamic and embolic events that may result in perioperative stroke during and after CEA in settings where monitoring is felt to be necessary (Type B, Class II-III).

Coronary Artery Bypass Graft (CABG) Surgery: TCD monitoring is probably useful (Type B, Class II-III) during CABG for detection of cerebral microemboli. TCD is possibly useful to document changes in flow velocities and CO2 reactivity during CABG surgery (Type C, Class III). Data are insufficient regarding the clinical impact of this information (Type U).

Vasomotor Reactivity Testing: TCD is probably useful (Type B, Class II-III) for the detection of impaired cerebral hemodynamics in patients with severe (>70%) asymptomatic extracranial ICA stenosis, symptomatic or asymptomatic extracranial ICA occlusion and cerebral small artery disease. Whether these techniques should be used to influence therapy and improve patient outcomes remains to be determined (Type U).

Vasospasm after traumatic subarachnoid hemorrhage: TCD is probably useful for the detection of VSP following traumatic SAH (Type B, Class III), but data are needed to show its accuracy and clinical impact in this setting (Type U).

Reimbursement

issues

TRANSCRANIAL DOPPLER

Technique

clinical applications

Clinical applications

STOP Trial

(Stroke Prevention Trial in Sickle Cell Anemia, 1998)

1. Sickle Cell Disease

Sickle cell anemia

Subarachnoid hemorrhage

Ischemic stroke

TIA (and amarousis fugax)

Intracranial stenosis

Cerebral circulatory arrest- brain death exam

Detection of right-left shunts

Screening for CEA/ CABG

Children/adolescent screening ages 2-16

Typically: (1) terminal ICA stenosis

(2) Terminal ICA/M1 MCA stenosis

(3) moya-moya (small vessel)

Studies have shown for TCD mean flow velocity ≥ 200, blood transfusion reduces stroke risk.

Sickle cell patients with TCD c/w MCA velocity > 200 cm/s at two visits

Randomized to blood transfusion group versus standard of care

Stroke occurrence 20 months follow-up:

1/63 transfused vs. 11/67 standard of care

90% relative risk reduction

2. Subarachnoid hemorrhage

4. CEA/CABG

Typical vasospasm occurs within first 5 days

Ischemia occurs days 7-12 after event

May require surgical/interventional procedure

See rapidly rising MCA mean velocities >200 cm/sec in first week. Precedes symptoms by hours-days.

(MCA sensitivity 80-90%, specificity 85%, Vert/basilar 75% sens, 80% spec)

Not reliable for ACA or distal MCA vasospasm.

TCCD can detect large and medium aneurysms.

Post and perioperative CEA/CABG

Not only intraoperative, but also following angioplasty, velocities should decrease

Pre-CEA—Vasoreactivity study

Breath holding index (percent increase in MCA mean velocity recorded by breath-holding divided by seconds of breath-holding ([Vbh-Vr/Vr] · 100 · s-1), helps determine candidates for carotid surgery:

BHI >0.69 4.1% stroke risk

BHI <0.69 13.9% stroke risk

3. AVM

Flow velocities in feeding vessels are high (140-200 cm/sec), PI is low (drop in resistance).

Can detect 2-4 cm sized AVM, but regularly misses small AVMs.

CEA

CVA is most common complication of CEA,

• caused by embolism, hypoperfusion during procedure.
• caused by hyperperfusion for 24-48 h after.
• TCD monitors MCA during operation.
• Cross clamping: MCA drops 60-90%. If mean velocity drops below 15 cm/sec, correlates with brain ischemia if not corrected.
• Shunting considered for patients with moderate to severe velocity drops. (practices range from >70%-85% drop in mean velocity, or 90% drop in PSV)
• Hyperperfusion syndrome: post-op persistent and severe velocity increase.
• Microembolism detection: perioperative and post operateive., particularly at cross-clamping common, but only during dissection phase, wound closure, and immediate post -op is associated with CVA. Determines use of antithrombotic agents during post-op period.
• More than 10 MES during dissection phase, or >20 MES per hour during postoperative phase are associated with CVA.

Guidelines

References

4. TCD in Stroke

Stroke work-up

Recommendations:

H&P

Head CT, EKG, blood work

CD and TCD and Echo

MRI/MRA

Localization of intracranial occlusion

Emboli detection

Bubble study-right to left shunt

Intracranial stenosis- cause 5-10% of strokes

(ICA siphon, MCA, M1, Vert-V4, prox-mid basilar)

Assessment of collaterals

Assessment of recanalization

* new ICD-9 codes for emboli detection and vasomotor reactivity/collaterals since 2006

Microembolism

Akopov S, et al. Hemodynamic Studies in Early Ischemic Stroke. Stroke 2002:33:1274

Alexandrov AV, et al. CLOTBUST:Design of a Randomized Trial of Ultrasound Enhanced Thrombolysis for Acute Ischemic Stroke. J Neuroimaging. 2004: 14 (2) 108-12

Babikian, Wechsler, Higashida. Imaging Cerebrovascular Disease 2003

Chimowitz MI, et al. Comparison of Warfarin and Aspirin for Symptomatic Intracranial Arterial Stenosis. N Eng J Med. 2005:352:1305-16

Komotar RJ, et al. Current Endovascular Treatment Options for Intracranial Carotid Artery Atherosclerosis. Neurosurg Focus 2005;18

Nichols FT, et al. Stroke Prevention in Sickle Cell Disease (STOP) Study Guidelines for Transcranial Doppler Testing. J Neuroimaging.2001; 11(4):354-62

Sauvageau E, et al. Recent Advances in Endoluminal Revascularization for Intracranial Atherosclerotic Disease. Neurol Res. 2005:27

Spence JD, et al. Absence of Microemboli on Transcranial Doppler Identifies Low-Risk Patients with Asymptomatic Carotid Stenosis. Stroke 2005; 36:2373-8

Clotbust

CLOTBUST criteria

Meets criteria for TPA

IV TPA initiated within 3 hours

MCA occlusion noted on TCD prior to TPA

TCD increased speed of lysis of TPA

Close to 40% achieved complete recanalization in less than 120 minutes.

Sustained outcome at 3 months.

“Combined Lysis of Thrombus in Brain ischemia using 2 MHZ transcranial Ultrasound and Systemic TPA”

Houston, Barcelona, Calgary, Edmonton,

NIH sponsored, 1984

TPA plus exposure to low frequency ultrasound may facilitate thrombolysis. (preliminary)

Cerebral emboli are particles or air that travel through the arteries of the brain and are an underlying pathogenic mechanism in many cases of stroke (Kaposzta et al. 1999). Emboli come from thrombus or atherosclerotic plaque located in the heart, carotid arteries, aorta, or vertebral arteries. Other sources include systemic venous thrombosis and thrombi from a coiled cerebral aneurysm. TCD plays a valuable role in detecting these microembolic signals in the cerebral circulation

Clinical Applications

of

TCD

Emboli detection in MCA stenosis

Disadvantages to TCD

Practical Application of TCD

TCD Advantages

Emboli detection in A Fib

Emboli detection in symptomatic ICA stenosis

Emboli detection in asymptomatic ICA Stenosis

36% positive MES in MCA stenosis

(emboli seen distal to stenosis)

6-15% positive MES in 1 hour

IF anticoagulated, rate of positive MES is lowered

Inexpensive

Accuracy

Grades stenosis better than mild/moderate/severe

Assessment of collateral flow—distal vasoreactivity: assess pulsatility indices. **marker of risk for lacunar infarcts

Vasospasm after SAH- cannot repeat angiography as often as necessary.

Portable

Claustrophobia

PPM

Quality of MRA/neuroradiologist

Insonation of cerebral veins, and sinuses (limited)

53.8 % positive microembolic signals in 1 hour of monitoring

Correlates with presence of ulceration.

Increased risk of stroke if emboli detected, independent from degree of stenosis.

Temporal bone window

inadequate in 10-20%

Factors: age, gender, race

Interpreting bias-interobserver and intermachine variability

no concensus for specific criteria for stenosis:

SONIA (Stroke Outcomes and Neuroimaging of Intracranial Arteries): mean velocity of 100 cm/sec MCA, 90 cm/sec ICA siphon presumed 50% stenosis.

25% of embolic strokes involve distal branches of MCA, ACA, PCA which cannot be insonated by TCD. This is improved with TCCD (but more expensive).

10-30% positive MES in 1 hour

Demonstrated increased risk of stroke with positive emboli, independent from degree of stenosis, but also correlates with degree of stenosis.

Stroke risk of 20% a year vs. 2% without emboli

Microemboli detection

Right-left shunt (PFO) detection

Intracranial stenosis/stroke

Vasomotor reactivity (lacunar infarcts, collaterals)

Sickle cell screening and management

Subarachonoid hemorrhage

CEA monitoring-intraoperative and preoperative

Brain death exam

Future—acute stroke adjunctive treatment?

Emboli Detection and Stroke subtype

Emboli detection in MI

Emboli detection in prosthetic heart valves

Microemboli detection for titrating antithrombotic therapy

17% of patients

RF: reduced EF, akinetic LV, LV thrombus, anterior wall MI

Usually air (vs. solid) emboli secondary to "cavitation" (movement of valves causes microbubble formation)

Signals have greater intensities, longer durations c/w gaseous emboli.

Reduction in emboli with 100% O2

Increased emboli with hyperbaric exposure

Lacunar infarcts rarely demonstrated positive MES

Most commonly associated with large vessel disease and patients with small DWI abnormalities

Emboli detection yield improves with longer monitoring periods-

Repeated or prolonged recordings of patients with carotid stenosis

150 minutes of detection is optimal

(most centers monitor 10-60 minutes)

Portable emboli detectors are available

Antithrombotics reduce/ extinguish MES

ASA bolus associated with marked drop in emboli counts- 25.1 vs. 6.4/hour

Emboli reduction correlates with recurrent stroke/TIA risk reduction

Collateral Flow changes cerebral autoregulation and vasoreactivity. Changes in response to carbon dioxide are mediated through arterioles and larger arteries at the base of the brain. Compensatory vasodilation causes fall in pulsatility index. The time of arrival of peak systolic velocity increases upstream. Therefore, patients with severe extracranial ICA stenosis with impaired distal vasoreactivity have arteriolar dilatation. This is associated with increased risk of future stroke. This test is used to assess risk for CEA, CABG.

TCD Bubble Study

Bubble studies

Detection of right-left shunt (PFO)

Venous injection of contrast agent or agitated saline is followed by microbubble signals on TCD within ten seconds.

9cc NS/1cc air agitated and injected into peripheral vein (18 guage push).

Performed at rest and with valsava.

Lower risk than TEE

TEE limited by inadequate valsava

Unable to visualize small bubbles on TEE

Increased sensitivity >91-100%, specificity 65-93% for identification of PFO, compared to TEE

Can detect Pulmonary AVM that TEE cannot.

Combined TCD bubble study and TEE increases detection rate compared to either alone.

Intracranial Stenosis

Accounts for 5-10% stroke.

Most common at ICA siphon, MCA M1,Vertebral V4, proximal-mid basilar arteries.

TCD/TCCD: increased peak systolic, end-diastolic, and mean velocities.

Increase in velocity is proportional to degree of stenosis.

No consensus regarding criteria for severity of stenosis.

SONIA (*Stroke Outcomes and Neuroimaging of Intracranial Atherosclerosis study, NIH): Mean velocity of 100 cm/sec for MCA, 90 cmsec for ICA siphon and supraclinoid segment, 80 cm/sec for distal vert and prox. basilar arteries indicate severity of stenosis of 50%.

(higher peak velocities : 180-220 cm/sec proposed for TCCD)

Longitudinal monitoring over time, irrespective of baseline velocities enables assessment of intracranial stenosis progression.

Practical Application: Intracranial Stenosis

WASID recommendations

ENDOVASCULAR OPTIONS

Not fully investigated, not standard of care, but may be option in particular for patients that fail antithrombotic and anticoagulation therapies.

Angioplasty with or without stent

High complication and mortality rate

Increased risk of vascular dissection or rupture

Undersized stent and incomplete angioplasty may reduce stroke risk with less complications

"Warfarin was associated with significantly higher rates of adverse events and provided no benefit over aspirin in this trial,"

"Aspirin should be used in preference to warfarin for patients with intracranial arterial stenosis."

“The role of vascular imaging (MRA, TCD, CTA, or catheter angiography) of the intracranial vessels as part of the initial evaluation of patients with transient ischemic attack or stroke needs to be reevaluated. Until therapy that is more effective than aspirin in combination with risk-factor management emerges, it could be argued that imaging of the intracranial vessels is unnecessary. On the other hand, identification of patients with intracranial stenosis has important prognostic implications, may influence treatment decisions (such as those regarding high-dose aspirin and aggressive risk-factor management), and may ultimately lead to more effective therapies for this high-risk disease.”

Warfarin-Aspirin Symptomatic Intracranial Disease (WASID) Trial :

symptomatic intracranial arterial stenosis: warfarin offers no benefit over aspirin but has a higher rate of adverse events, (New England Journal of Medicine March 31, 2005).

Double-blind, multicenter trial, patients with TIA or stroke caused by angiographically confirmed 50% to 99% stenosis of a major intracranial artery randomized to receive warfarin, with goal INR of 2-3, or aspirin, 1,300 mg per day.

Primary outcome was ischemic stroke, brain hemorrhage, or death from vascular causes other than stroke.

Trial was stopped after 569 patients were randomized because of warfarin safety concerns. During mean follow-up of 1.8 years, adverse events included death (4.3% for aspirin vs 9.7% for warfarin); major hemorrhage (3.2% vs 8.3%); and myocardial infarction or sudden death (2.9% vs 7.3%); Mortality from vascular causes was 3.2% for aspirin and 5.9% for warfarin. Mortality from nonvascular causes was 1.1% and 3.8%. The primary end point occurred in 22.1% of patients receiving aspirin and in 21.8% of patients receiving warfarin.

Neurology, September 2005 (Kern, et al): Higher recurrence rate of ischemic events in symptomatic middle cerebral artery disease (9.1% annual) compared to symptomatic extracranial carotid artery disease.

Asymptomatic MCA and extracranial ICA stenosis have comparable annual TIA and stroke risk of 2.8%

TCD is 80-90% sensitive at ICA siphon and MCA M1, >95% specific.

TCCD has > 98% sensitivity and specificity for same segments

Less accurate at V4 and proximal basilar artery (TCD 70%/85%, TCCD 70%, 98%).

Versus MRA

Therapeutic implications of TCD results

Vague symptoms of dizziness, visual disturbance may be indication of vertebrobasilar ischemia.

Vertebrobasilar stenosis may be indication for anticoagulation or other medical and non-medical treatment.

Accuracy questioned for both MRA and TCD

Gadolinium enhanced is better-

*Gad measures the lumen, has no artifacts, better resolution than time of flight. Can show flow where non-enhanced MRA concluded occlusion.

* problem with venous enhancement, and leak of gad.

Covers large area

Overestimated severity of disease

3-D Time of Flight limited by fresh spins. Later exposure causes saturation of spins, no further signal is elicited.

2-D TOF: poorer resolution, greater noise, but covers greater area

Phase contrast MRA—takes longer (4x) than TOF—good for subacute hemorrhage. Can determine direction and velocity of flowing blood.

TCD-80-90% sensitive , 95% specific, in lesions of ICA siphon, M1 (TCCD has specificity >98%)

Both techniques less accurate when evaluating Vert V4 segment and prox Basilar. TCD: 70% sens 85% spec. (70% and 98% TCCD)

MRA better for distal basilar lesions.

TCD better at detecting stenoses than occlusions. (TCCD is more accurate)

Versus CTA

Contrast enhanced

?Possible neurotoxicity of contrast agent (ionic agent)

Nephrotoxicity with contrast agent

Idiosyncratic reaction to contrast

Radiation dose (not considered significant in older patient population)

Rapid results

Requires reformatting

less standardized post-processing

CTA sens. 83%, spec. 99% compared to MRA for intracranial stenoses and occlusions.

Less reliable for MCA branch occlusions.

Unable to measure flow volume or velocity.

Cannot predict collateral flow.

bone artifact

technique

Artery identification

Artery Depth (mm) Direction

MCA 30-67 toward

ACA 60-80 away

T-ICA 60-67 toward

PCA 55-75 toward

Opth 40-60 toward

Siphon 60-80 variable

Vertebral 40-85 away

Basilar >80 away

ICA-sub 35-70 away

ACA

OA

MCA-ACA

MCA

BA

PCA

Velocity Norms

microemboli

Vasomotor Reactivity Study.

Left ICA is occluded.

Baseline, R MCA is normal, L MCA is blunted.

With breath holding (hypercarbia), right MCA side increases velocity more than left. Hyperventilation causes rapid drop in right MCA, blunted on left.

Sample report:

HEAD ROTATION TEST

Rotational vertebrobasilar ischemia (RVBI) occurs with changes of head and neck position.

Protocol:

1.Patient sits upright in a chair.

2. Monitor the bilateral PCA-Pl using a headframe and two 2 MHz TCD probes fixated on the transtemporal window. .

During head turning maneuvers the patient keeps eyes open, uses full range of motion, turns head slowly, and holds the position for at least five cardiac cycles before turning head back to a neutral position.

Each maneuver should be performed twice.

Record baseline velocities before each position. Velocities are recorded during the head turning maneuver and when returns to the neutral position.

The maneuvers are:

1. Head turned to the right.

2. Head turned to the right and tilted upward.

3. Head turned to the left.

4. Head turned to the left and tilted upward.

5. Head flexed forward.

6. Head extended backward.

Interpretation

The study is positive if there is a greater than 40% decrease in blood flow or loss of blood flow in the PCAs. This must also be accompanied by a hyperemic response (increase in blood flow velocity greater than the baseline flow velocity) as the head is turned back to the neutral position

Spectral waveform of the PCA demonstrating cessation of flow with the head returned to a neutral position.

The bilateral posterior cerebral arteries (PCA) are monitored during head turning. The flow velocities drop when the head is turned and a hyperemic response is seen with the head returnded to a neutral position