RESUMEN
Today, it seems prudent to reconsider how ultrasound technology can be used for providing intraoperative neurophysiologic monitoring that will result in better patient outcomes and decreased length and cost of hospitalization. An extensive and rapidly growing literature suggests that the essential hemodynamic information provided by transcranial Doppler (TCD) ultrasonography neuromonitoring (TCDNM) would provide effective monitoring modality for improving outcomes after different types of vascular, neurosurgical, orthopedic, cardiovascular, and cardiothoracic surgeries and some endovascular interventional or diagnostic procedures, like cardiac catheterization or cerebral angiography. Understanding, avoiding, and preventing peri- or postoperative complications, including neurological deficits following abovementioned surgeries, endovascular intervention, or diagnostic procedures, represents an area of great public and economic benefit for society, especially considering the aging population. The American Society of Neurophysiologic Monitoring and American Society of Neuroimaging Guidelines Committees formed a joint task force and developed updated guidelines to assist in the use of TCDNM in the surgical and intensive care settings. Specifically, these guidelines define (1) the objectives of TCD monitoring; (2) the responsibilities and behaviors of the neurosonographer during monitoring; (3) instrumentation and acquisition parameters; (4) safety considerations; (5) contemporary rationale for TCDNM; (6) TCDNM perspectives; and (7) major recommendations.
Asunto(s)
Ultrasonido , Ultrasonografía Doppler Transcraneal , Anciano , Circulación Cerebrovascular , Cuidados Críticos , Humanos , Neuroimagen , Complicaciones Posoperatorias , Ultrasonografía Doppler Transcraneal/métodosRESUMEN
The American Society of Neurophysiologic Monitoring (ASNM) and American Society of Neuroimaging (ASN) Guidelines Committees formed a joint task force and developed guidelines to assist in the use of transcranial Doppler (TCD) monitoring in the surgical and intensive care settings. Specifically, these guidelines: (1) delineate the objectives of TCD monitoring; (2) characterize the responsibilities and behaviors of the sonographer during monitoring; (3) describe methodological and ethical issues uniquely relevant to monitoring. The ASNM and ASN strongly support the positions that (1) acquisition and interpretation of intraoperative TCD ultrasonograms be performed by qualified individuals, (2) service providers define their diagnostic criteria and develop on-going self-validation programs of these performance criteria in their practices. We agree with the guidelines of other professional societies regarding the technical and professional qualifications of individuals responsible for TCD signal acquisition and interpretation (Class III evidence, Type C recommendation). On the basis of current clinical literature and scientific evidence, TCD monitoring is an established monitoring modality for the: (1) assessment of cerebral vasomotor reactivity and autoregulation; (2) documentation of the circle of Willis functional status; (3) identification of cerebral hypo- and hyperperfusion, recanalization and re-occlusion; and (4) detection of cerebral emboli (Class II and III evidence, Type B recommendation).
Asunto(s)
Trastornos Cerebrovasculares/diagnóstico por imagen , Trastornos Cerebrovasculares/fisiopatología , Unidades de Cuidados Intensivos , Neurofisiología , Ultrasonografía Doppler Transcraneal/normas , Trastornos Cerebrovasculares/terapia , Humanos , Sociedades Médicas , Estados UnidosRESUMEN
OBJECTIVE: Cavum Septum Pellucidum (CSP) cysts are considered normal anatomic variants, comprising as many as 15% of the adult and 85% of pediatric populations. On rare occasions, the cavum can obstruct CSF outflow from the lateral ventricles causing elevated intracranial pressure (ICP) and headaches. The purpose of this paper is to present a challenging case of new onset symptomatic CSP in a previously healthy adult male without papilledema and elevated ICP detected by transcranial Doppler (TCD) ultrasonography. CLINICAL PRESENTATION: A previously healthy 44 year-old man presented to the neurology service with debilitating positional headaches that were mitigated solely by recumbent positioning. A magnetic resonance imaging scan (MRI) of the brain revealed a cavum septum pellucidum. A lumbar puncture was performed and revealed normal ICP. No papilledema was evident on fundoscopic examination. A CSF flow study revealed normal dye opacification pattern without evidence of CSF leak. INTERVENTION: Without other clinical indicators of high ICP, but a history suspicious for symptomatic CSP, TCD study was performed and revealed abnormally low cerebral blood flow velocities (CBFV's) and significantly elevated pulsatility indices (PI's) for patient's age indicative of high ICP. Endoscopic fenestration of the septum pellucidum was performed improving the patient's headaches and normalization of the PI's and CBFV's to normal (p<0.01). CONCLUSIONS: Symptomatic CSP is a difficult diagnosis to make based on existing diagnostic paradigm. TCD in the absence of other objective confirmatory studies, can aid in the diagnosis and provide information about the success of fenestration of the cavum septum.
RESUMEN
Indications for the clinical use of transcranial Doppler (TCD) continue to expand while scanning protocols and quality of reporting vary between institutions. Based on literature analysis and extensive personal experience, an international expert panel started the development of guidelines for TCD performance, interpretation, and competence. The first part describes complete diagnostic spectral TCD examination for patients with cerebrovascular diseases. Cranial temporal bone windows are used for the detection of the middle cerebral arteries (MCA), anterior cerebral arteries (ACA), posterior cerebral arteries (PCA), C1 segment of the internal carotid arteries (ICA), and collateralization of flow via the anterior (AComA) and posterior (PComA) communicating arteries; orbital windows-for the ophthalmic artery (OA) and ICA siphon; the foraminal window-for the terminal vertebral (VA) and basilar (BA) arteries. Although there is a significant individual variability of the circle of Willis with and without disease, the complete diagnostic TCD examination should include bilateral assessment of the M2 (arbitrarily located at 30-40 mm depth), M1 (40-65 mm) MCA [with M1 MCA mid-point at 50 mm (range 45-55 mm), average length 16 mm (range 5-24 mm), A1 ACA (60-75 mm), C1 ICA (60-70 mm), P1-P2 PCA (average depth 63 mm (range 55-75 mm), AComA (70-80 mm), PComA (58-65 mm), OA (40-50 mm), ICA siphons (55-65 mm), terminal VA (40-75 mm), proximal (75-80), mid (80-90 mm), and distal (90-110 mm) BA]. The distal ICA on the neck (40-60 mm) can be located via submandibular windows to calculate the VMCA/VICA index, or the Lindegaard ratio for vasospasm grading after subarachnoid hemorrhage. Performance goals of diagnostic TCD are to detect and optimize arterial segment-specific spectral waveforms, determine flow direction, measure cerebral blood flow velocities and flow pulsatility in the above-mentioned arteries. These practice standards will assist laboratory accreditation processes by providing a standard scanning protocol with transducer positioning and orientation, depth selection and vessel identification for ultrasound devices equipped with spectral Doppler and power motion Doppler.
Asunto(s)
Ultrasonografía Doppler Transcraneal/normas , Humanos , Ultrasonografía Doppler Transcraneal/métodosRESUMEN
Cardiac surgery (CS) with cardiopulmonary bypass (CPB) is currently the most common surgery in the United States. Understanding, avoiding, and preventing postoperative complications, including neurologic deficits following CS, represents a great public and economic benefit for society, especially considering our aging population. There is a critical need to identify new strategies that will prevent harmful events during and after CS. At present, experience with neurophysiologic techniques includes the ability to measure cerebral blood flow velocity/emboli and regional cerebral venous oxygen saturation by transcranial Doppler ultrasound, and by near-infrared spectroscopy, respectively. Continuous monitoring of these variables along with systemic hemodynamics will provide a better understanding of mechanisms of brain and other organ injury during CPB. Neuroprotective interventions based on multimodality neurologic monitoring would ideally eliminate postoperative complications and improve patient outcomes.
Asunto(s)
Aterosclerosis/cirugía , Lesiones Encefálicas/prevención & control , Circulación Cerebrovascular/fisiología , Puente de Arteria Coronaria , Embolia Intracraneal/prevención & control , Monitoreo Intraoperatorio/métodos , Complicaciones Posoperatorias/prevención & control , Velocidad del Flujo Sanguíneo , Lesiones Encefálicas/etiología , Humanos , Embolia Intracraneal/etiología , Espectroscopía Infrarroja CortaRESUMEN
BACKGROUND AND PURPOSE: Patients with a combination of atrial septal aneurysm (ASA) and patent foramen ovale (PFO) have a substantially higher rate of recurrent ischemic events as compared to PFO alone. One possible explanation is a greater degree of right-to-left shunting with the combination. METHODS: Retrospective study using contrast transcranial Doppler ultrasonography (c-TCD) to study the degree of shunting in 46 patients with PFO with either transient ischemic attack or cryptogenic ischemic stroke. Eight patients with PFO+ASA identified on transesophageal echocardiogram were compared to 38 patients with PFO but without ASA. RESULTS: The number of embolic counts was no different with or without an ASA. Valsalva maneuver increased number of emboli, especially in patients with large PFOs. CONCLUSIONS: Patients with ASA in addition to PFO do not appear to have an increased risk of right-to-left shunting as measured by c-TCD as compared to PFO alone.
Asunto(s)
Aneurisma Cardíaco/diagnóstico por imagen , Defectos del Tabique Interatrial/diagnóstico por imagen , Ataque Isquémico Transitorio/diagnóstico por imagen , Accidente Cerebrovascular/diagnóstico por imagen , Ultrasonografía Doppler Transcraneal , Estudios de Casos y Controles , Medios de Contraste , Ecocardiografía Transesofágica , Femenino , Atrios Cardíacos , Humanos , Embolia Intracraneal/diagnóstico por imagen , Masculino , Microburbujas , Persona de Mediana Edad , Recurrencia , Estudios Retrospectivos , Factores de Riesgo , Maniobra de ValsalvaRESUMEN
BACKGROUND AND PURPOSE: There is an unmet need to classify cerebrovascular conditions physiologically and to assess cerebrovascular system performance. The authors hypothesized that by simultaneously considering the dynamic parameters of flow velocity, acceleration, and pulsatility index (PI) (impedance) in individual Doppler spectrum waveforms, they could develop an objective method to elucidate the pathophysiology of vascular conditions and classify cerebrovascular disorders. This method, dynamic vascular analysis (DVA), is described. METHODS: First, a theoretical model was developed to determine how any vascular segment and the ensemble of intracranial vascular segments could be defined according to its dynamic physiological characteristics. Next, the DVA method was applied to 847 anonymous serial complete clinical transcranial Doppler (TCD) studies of patients without regard for their diagnosis to ascertain actual reference ranges and the normality of the distribution curves for each dimension of the 3-parameter nomogram. The authors applied DVA to 2 clinical cases to see if they could track the changes in vascular performance of 2 known progressive diseases. RESULTS: The theoretical analysis identified 295,245 possible vascular states for the ensemble of vascular segments in the cerebral circulation. When applied to clinical TCD data, DVA revealed continuous, normally distributed data for the velocity, PI, and logarithm of the acceleration. CONCLUSIONS: DVA is proposed as a method for monitoring the physiological state of each cerebral artery segment individually and in ensemble. DVA evaluates the relationship among acceleration (force or pressure), velocity, and PI and provides an objective means to evaluate intracranial vascular segments using the paradigm of the well-described pressure-perfusion autoregulation relationship. DVA may be used to study cerebrovascular pathophysiology and to classify, evaluate, and monitor cerebrovascular disorders or systemic disorders with cerebrovascular effects.
Asunto(s)
Presión Sanguínea/fisiología , Trastornos Cerebrovasculares/diagnóstico por imagen , Diagnóstico por Computador/instrumentación , Sistemas Especialistas/instrumentación , Aumento de la Imagen/instrumentación , Procesamiento de Imagen Asistido por Computador/instrumentación , Ultrasonografía Doppler Transcraneal/instrumentación , Adulto , Anciano , Anciano de 80 o más Años , Velocidad del Flujo Sanguíneo/fisiología , Encéfalo/irrigación sanguínea , Arterias Cerebrales/diagnóstico por imagen , Arterias Cerebrales/fisiopatología , Trastornos Cerebrovasculares/clasificación , Trastornos Cerebrovasculares/fisiopatología , Análisis por Conglomerados , Diagnóstico Diferencial , Femenino , Humanos , Malformaciones Arteriovenosas Intracraneales/clasificación , Malformaciones Arteriovenosas Intracraneales/diagnóstico por imagen , Malformaciones Arteriovenosas Intracraneales/fisiopatología , Masculino , Cómputos Matemáticos , Probabilidad , Estudios Prospectivos , Flujo Pulsátil/fisiología , Valores de Referencia , Flujo Sanguíneo Regional/fisiología , Sensibilidad y Especificidad , Síndromes de la Apnea del Sueño/clasificación , Síndromes de la Apnea del Sueño/diagnóstico por imagen , Síndromes de la Apnea del Sueño/fisiopatología , Diseño de Software , Evaluación de la Tecnología Biomédica , Tálamo/irrigación sanguíneaRESUMEN
BACKGROUND AND PURPOSE: During the evaluation of acute ischemic stroke with diffusion- and perfusion-weighted magnetic resonance imaging (DWI and PWI, respectively), the presence of salvageable brain tissue is suggested by the occurrence of a perfusion-diffusion "mismatch." DWI and PWI, however, are not universally available and have inherent inconveniences, which justify a search for practical diagnostic alternatives. The purpose of this study is to investigate whether there are transcranial Doppler (TCD) markers of mismatch. METHODS: Retrospective analysis of 22 patients with acute ischemic stroke affecting the middle cerebral artery (MCA) territory, who had a TCD performed within 24 hours of magnetic resonance imaging (MRI) with DWI and PWI. RESULTS: MRI and TCD were performed on average 10.8 +/- 9.2 hours apart. Time from symptom onset to MRI and TCD completion were 1.6 +/- 1.6 and 2 +/- 1.9 days, respectively. MCA and intracranial internal carotid artery (ICA) cerebral blood flow velocity (CBFV) asymmetry, together with a large ICA-to-MCA gradient, were associated with the presence of mismatch. The combined use of 2 TCD parameters (MCA CBFV asymmetry of > or = 30% and ICA-to-MCA gradient > or = 20 cm/sec) had a sensitivity of 75%, specificity of 80%, positive predictive value of 82%, and negative predictive value of 73% at detecting mismatch cases. CONCLUSIONS: Diffusion-perfusion mismatch appears to be associated with interhemispheric asymmetry between MCA and ICA CBFVs, and a large CBFV gradient between the ICA and MCA on the affected side. Prospective studies are required to verify these observations and to determine whether TCD can be used to follow patients with mismatch.
Asunto(s)
Accidente Cerebrovascular/diagnóstico por imagen , Accidente Cerebrovascular/fisiopatología , Ultrasonografía Doppler Transcraneal , Adulto , Anciano , Anciano de 80 o más Años , Velocidad del Flujo Sanguíneo , Difusión , Femenino , Humanos , Imagen por Resonancia Magnética/métodos , Masculino , Persona de Mediana Edad , Sensibilidad y Especificidad , Accidente Cerebrovascular/diagnósticoRESUMEN
BACKGROUND AND PURPOSE: During head-up tilt (HUT), patients with chronic fatigue syndrome (CFS) have higher rates of neurally mediated hypotension (NMH) and postural tachycardia syndrome (POTS) than healthy controls. The authors studied whether patients with CFS were also more likely to have abnormal cerebral blood flow velocity (CBFV) compared with controls in response to orthostatic stress. METHODS: Transcranial Doppler monitoring of middle cerebral artery (MCA) CBFV was performed during 3-stage HUT prospectively in 26 patients with CFS and 23 healthy controls. At the same time, continuous monitoring of arterial blood pressure (BP), heart rate (HR), endtidal CO2 (ET-CO2) were performed. Results are reported as mean +/- SD. RESULTS: NMH developed in 21 patients with CFS and in 14 controls (P = .22). POTS was present in 9 CFS patients and 7 controls (P = .76). Supine HR was higher in CFS patients, but all other hemodynamics and CBFV measures were similar at baseline. The median time to hypotension did not differ, but the median time to onset of orthostatic symptoms was shorter in those with CFS (P < .001). The CBFV did not differ between groups in the supine posture, at 1 or 5 minutes after upright tilt, at 5 or 1 minute before the end of the test, or at termination of the test. Mean CBFV fell at termination of tilt testing in those with CFS and controls. ET-CO2 was lower at termination of the test in those with CFS versus controls (P = .002). CONCLUSIONS: The results of this study are not consistent with the hypothesis that patients with CFS have a distinctive pattern of MCA CBFV changes in response to orthostatic stress.
Asunto(s)
Encéfalo/irrigación sanguínea , Síndrome de Fatiga Crónica/fisiopatología , Inclinación de Cabeza/fisiología , Hemodinámica/fisiología , Adulto , Velocidad del Flujo Sanguíneo , Presión Sanguínea/fisiología , Síndrome de Fatiga Crónica/diagnóstico por imagen , Femenino , Humanos , Masculino , Arteria Cerebral Media/diagnóstico por imagen , Arteria Cerebral Media/fisiología , Flujo Sanguíneo Regional , Estadísticas no Paramétricas , Ultrasonografía Doppler TranscranealRESUMEN
Intraventricular hemorrhage (IVH) occurred in a 32-year-old man following the use of both ephedrine and pseudoephedrine. Cerebral angiography and transcranial Doppler studies showed changes suggestive of vasculitis. We describe the management and investigations of a unique case of IVH. This patient was treated with ventriculostomy and intraventricular urokinase (UK). A favorable outcome was obtained with independent function at 10 weeks post hemorrhage. The use of intraventricular thrombolysis for drug-induced IVH has not previously been reported, although it has been shown to be a safe and potentially beneficial intervention.
Asunto(s)
Anemia de Células Falciformes/complicaciones , Accidente Cerebrovascular/diagnóstico por imagen , Ultrasonografía Doppler Transcraneal/métodos , Adolescente , Anemia de Células Falciformes/fisiopatología , Velocidad del Flujo Sanguíneo , Arteria Carótida Interna/diagnóstico por imagen , Niño , Preescolar , Ecoencefalografía , Femenino , Humanos , Masculino , Arteria Cerebral Media/diagnóstico por imagen , Factores de Riesgo , Accidente Cerebrovascular/etiología , Ultrasonografía DopplerRESUMEN
INTRODUCTION: Intracerebral hemorrhage (ICH) associated with pregnancy commonly occurs in the postpartum period in the setting of preeclampsia/eclampsia. We describe the clinical course of two patients with ICH due to postpartum cerebral vasculopathy in the absence of toxemia. METHODS: We reviewed two cases with ICH and postpartum vasculopathy in our hospital (1996-2001) and compared them with seven similar case reports from the literature. RESULTS: Mean age of all patients is 28.7+/-5.6 years (mean+/-S.D.). Toxemia of pregnancy was absent in all cases. ICHs were cortical in eight and putaminal in one patient. Erythrocyte sedimentation rate was elevated in two. Two cases rehemorrhaged during the same admission. No cerebral infarctions were reported. All patients had diffuse vasculopathy on conventional catheter angiography, with no clinical manifestations or laboratory data supportive of extracerebral or systemic vasculitis. Eight patients were treated with corticosteroids, two with additional cytotoxic agents and one with nimodipine alone. Improvement on follow-up cerebral angiography (catheter or MRA) and transcranial Doppler ultrasonography (TCD) was noted in eight cases. One did not have follow-up cerebral imaging but had an excellent clinical outcome. All cases had good to excellent functional recovery. CONCLUSIONS: Postpartum ICH in the absence of toxemia may be associated with isolated cerebral vasculopathy. The clinical course and functional outcome is good to excellent. This entity appears to be distinct from cerebral vasculitis, which is usually associated with poor outcome.
Asunto(s)
Hemorragia Cerebral/complicaciones , Trastornos Cerebrovasculares/complicaciones , Corticoesteroides/uso terapéutico , Adulto , Hemorragia Cerebral/diagnóstico por imagen , Hemorragia Cerebral/tratamiento farmacológico , Hemorragia Cerebral/radioterapia , Trastornos Cerebrovasculares/diagnóstico por imagen , Femenino , Estudios de Seguimiento , Humanos , Angiografía por Resonancia Magnética , Periodo Posparto , Embarazo , Complicaciones del Embarazo , Tomografía Computarizada por Rayos X , Resultado del Tratamiento , Ultrasonografía Doppler TranscranealRESUMEN
OBJECTIVE: To evaluate the reliability of transcranial Doppler ultrasound in detecting symptomatic vasospasm in patients after aneurysmal subarachnoid hemorrhage and monitoring response after hypertensive and endovascular treatments. DESIGN: Retrospective chart review. SETTING: Neurosciences critical care unit in a tertiary-care university hospital. PATIENTS: All patients admitted to a neurosciences critical care unit with the diagnosis of subarachnoid hemorrhage between January 1990 and June 1997. INTERVENTIONS: None MEASUREMENTS AND MAIN RESULTS: We reviewed transcranial Doppler ultrasound data of 199 patients; 55 had symptomatic vasospasm. Clinical symptoms and corresponding vascular distributions were identified, as was angiographic vasospasm (n = 35). The sensitivity and specificity of transcranial Doppler ultrasound for anterior circulation vessels were calculated by using a mean cerebral blood flow velocity criterion of >120 cm/sec. Clinical diagnosis of symptomatic vasospasm was used as the standard to determine sensitivity and specificity of transcranial Doppler ultrasound and cerebral angiography. The sensitivity of transcranial Doppler ultrasound for anterior circulation in patients with symptomatic vasospasm was 73% with a specificity of 80%. The sensitivity of cerebral angiography was 80%. For individual vessels, the sensitivity and specificity of transcranial Doppler ultrasound were middle cerebral artery, 64% and 78%; anterior cerebral artery, 45% and 84%; and internal carotid artery, 80% and 77%, respectively. The mean times for symptomatic and transcranial Doppler ultrasound signs of vasospasm presentation were 6.4 +/- 2 and 6.1 +/- 3 days, respectively. In patients without symptomatic vasospasm, the mean time for mean cerebral blood flow velocities >120 cm/sec was 7.0 +/- 3 days (p <.05). Symptomatic vasospasm also was associated with thickness of clot on head computed tomography scan and rapidly increasing mean cerebral blood flow velocities. Transcranial Doppler ultrasound signs of vasospasm improved after endovascular treatment in 30 patients. CONCLUSIONS: The reliability of transcranial Doppler ultrasound was better at detecting high mean cerebral blood flow velocities in patients with symptomatic vasospasm related to middle cerebral and internal carotid artery distributions than for anterior cerebral artery distribution. Transcranial Doppler ultrasound was as sensitive as cerebral angiography at detecting symptomatic vasospasm. High mean cerebral blood flow velocities can be apparent before the presence of symptomatic vasospasm. Daily transcranial Doppler ultrasound monitoring could provide early identification of patients with aneurysmal subarachnoid hemorrhage who are at high risk for symptomatic vasospasm and may be helpful at following success of endovascular treatment.